Merge tag 'for-4.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs updates from David Sterba:
 "Features or user visible changes:

   - fallocate: implement zero range mode

   - avoid losing data raid profile when deleting a device

   - tree item checker: more checks for directory items and xattrs

  Notable fixes:

   - raid56 recovery: don't use cached stripes, that could be
     potentially changed and a later RMW or recovery would lead to
     corruptions or failures

   - let raid56 try harder to rebuild damaged data, reading from all
     stripes if necessary

   - fix scrub to repair raid56 in a similar way as in the case above

  Other:

   - cleanups: device freeing, removed some call indirections, redundant
     bio_put/_get, unused parameters, refactorings and renames

   - RCU list traversal fixups

   - simplify mount callchain, remove recursing back when mounting a
     subvolume

   - plug for fsync, may improve bio merging on multiple devices

   - compression heurisic: replace heap sort with radix sort, gains some
     performance

   - add extent map selftests, buffered write vs dio"

* tag 'for-4.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (155 commits)
  btrfs: drop devid as device_list_add() arg
  btrfs: get device pointer from device_list_add()
  btrfs: set the total_devices in device_list_add()
  btrfs: move pr_info into device_list_add
  btrfs: make btrfs_free_stale_devices() to match the path
  btrfs: rename btrfs_free_stale_devices() arg to skip_dev
  btrfs: make btrfs_free_stale_devices() argument optional
  btrfs: make btrfs_free_stale_device() to iterate all stales
  btrfs: no need to check for btrfs_fs_devices::seeding
  btrfs: Use IS_ALIGNED in btrfs_truncate_block instead of opencoding it
  Btrfs: noinline merge_extent_mapping
  Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping
  Btrfs: extent map selftest: dio write vs dio read
  Btrfs: extent map selftest: buffered write vs dio read
  Btrfs: add extent map selftests
  Btrfs: move extent map specific code to extent_map.c
  Btrfs: add helper for em merge logic
  Btrfs: fix unexpected EEXIST from btrfs_get_extent
  Btrfs: fix incorrect block_len in merge_extent_mapping
  btrfs: Remove unused readahead spinlock
  ...

44 files changed, 2259 insertions, 1399 deletions

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 6fe881d5cb38..0c4373628eb4 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -19,4 +19,4 @@ btrfs-$(CONFIG_BTRFS_FS_REF_VERIFY) += ref-verify.o
 btrfs-$(CONFIG_BTRFS_FS_RUN_SANITY_TESTS) += tests/free-space-tests.o \
 	tests/extent-buffer-tests.o tests/btrfs-tests.o \
 	tests/extent-io-tests.o tests/inode-tests.o tests/qgroup-tests.o \
-	tests/free-space-tree-tests.o
+	tests/free-space-tree-tests.o tests/extent-map-tests.o
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 7d0dc100a09a..e4054e533f6d 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -216,7 +216,8 @@ static int prelim_ref_compare(struct prelim_ref *ref1,
 	return 0;
 }
 
-void update_share_count(struct share_check *sc, int oldcount, int newcount)
+static void update_share_count(struct share_check *sc, int oldcount,
+			       int newcount)
 {
 	if ((!sc) || (oldcount == 0 && newcount < 1))
 		return;
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 75610d23d197..07d049c0c20f 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -33,7 +33,6 @@
 #include <linux/bit_spinlock.h>
 #include <linux/slab.h>
 #include <linux/sched/mm.h>
-#include <linux/sort.h>
 #include <linux/log2.h>
 #include "ctree.h"
 #include "disk-io.h"
@@ -45,6 +44,21 @@
 #include "extent_io.h"
 #include "extent_map.h"
 
+static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" };
+
+const char* btrfs_compress_type2str(enum btrfs_compression_type type)
+{
+	switch (type) {
+	case BTRFS_COMPRESS_ZLIB:
+	case BTRFS_COMPRESS_LZO:
+	case BTRFS_COMPRESS_ZSTD:
+	case BTRFS_COMPRESS_NONE:
+		return btrfs_compress_types[type];
+	}
+
+	return NULL;
+}
+
 static int btrfs_decompress_bio(struct compressed_bio *cb);
 
 static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
@@ -348,8 +362,6 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 		page->mapping = NULL;
 		if (submit || bio_add_page(bio, page, PAGE_SIZE, 0) <
 		    PAGE_SIZE) {
-			bio_get(bio);
-
 			/*
 			 * inc the count before we submit the bio so
 			 * we know the end IO handler won't happen before
@@ -372,8 +384,6 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 				bio_endio(bio);
 			}
 
-			bio_put(bio);
-
 			bio = btrfs_bio_alloc(bdev, first_byte);
 			bio->bi_opf = REQ_OP_WRITE | write_flags;
 			bio->bi_private = cb;
@@ -389,7 +399,6 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 		first_byte += PAGE_SIZE;
 		cond_resched();
 	}
-	bio_get(bio);
 
 	ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
 	BUG_ON(ret); /* -ENOMEM */
@@ -405,7 +414,6 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 		bio_endio(bio);
 	}
 
-	bio_put(bio);
 	return 0;
 }
 
@@ -638,8 +646,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 		page->mapping = NULL;
 		if (submit || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
 		    PAGE_SIZE) {
-			bio_get(comp_bio);
-
 			ret = btrfs_bio_wq_end_io(fs_info, comp_bio,
 						  BTRFS_WQ_ENDIO_DATA);
 			BUG_ON(ret); /* -ENOMEM */
@@ -666,8 +672,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 				bio_endio(comp_bio);
 			}
 
-			bio_put(comp_bio);
-
 			comp_bio = btrfs_bio_alloc(bdev, cur_disk_byte);
 			bio_set_op_attrs(comp_bio, REQ_OP_READ, 0);
 			comp_bio->bi_private = cb;
@@ -677,7 +681,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 		}
 		cur_disk_byte += PAGE_SIZE;
 	}
-	bio_get(comp_bio);
 
 	ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA);
 	BUG_ON(ret); /* -ENOMEM */
@@ -693,7 +696,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 		bio_endio(comp_bio);
 	}
 
-	bio_put(comp_bio);
 	return 0;
 
 fail2:
@@ -752,6 +754,8 @@ struct heuristic_ws {
 	u32 sample_size;
 	/* Buckets store counters for each byte value */
 	struct bucket_item *bucket;
+	/* Sorting buffer */
+	struct bucket_item *bucket_b;
 	struct list_head list;
 };
 
@@ -763,6 +767,7 @@ static void free_heuristic_ws(struct list_head *ws)
 
 	kvfree(workspace->sample);
 	kfree(workspace->bucket);
+	kfree(workspace->bucket_b);
 	kfree(workspace);
 }
 
@@ -782,6 +787,10 @@ static struct list_head *alloc_heuristic_ws(void)
 	if (!ws->bucket)
 		goto fail;
 
+	ws->bucket_b = kcalloc(BUCKET_SIZE, sizeof(*ws->bucket_b), GFP_KERNEL);
+	if (!ws->bucket_b)
+		goto fail;
+
 	INIT_LIST_HEAD(&ws->list);
 	return &ws->list;
 fail:
@@ -1278,13 +1287,103 @@ static u32 shannon_entropy(struct heuristic_ws *ws)
 	return entropy_sum * 100 / entropy_max;
 }
 
-/* Compare buckets by size, ascending */
-static int bucket_comp_rev(const void *lv, const void *rv)
+#define RADIX_BASE		4U
+#define COUNTERS_SIZE		(1U << RADIX_BASE)
+
+static u8 get4bits(u64 num, int shift) {
+	u8 low4bits;
+
+	num >>= shift;
+	/* Reverse order */
+	low4bits = (COUNTERS_SIZE - 1) - (num % COUNTERS_SIZE);
+	return low4bits;
+}
+
+/*
+ * Use 4 bits as radix base
+ * Use 16 u32 counters for calculating new possition in buf array
+ *
+ * @array     - array that will be sorted
+ * @array_buf - buffer array to store sorting results
+ *              must be equal in size to @array
+ * @num       - array size
+ */
+static void radix_sort(struct bucket_item *array, struct bucket_item *array_buf,
+		       int num)
 {
-	const struct bucket_item *l = (const struct bucket_item *)lv;
-	const struct bucket_item *r = (const struct bucket_item *)rv;
+	u64 max_num;
+	u64 buf_num;
+	u32 counters[COUNTERS_SIZE];
+	u32 new_addr;
+	u32 addr;
+	int bitlen;
+	int shift;
+	int i;
 
-	return r->count - l->count;
+	/*
+	 * Try avoid useless loop iterations for small numbers stored in big
+	 * counters.  Example: 48 33 4 ... in 64bit array
+	 */
+	max_num = array[0].count;
+	for (i = 1; i < num; i++) {
+		buf_num = array[i].count;
+		if (buf_num > max_num)
+			max_num = buf_num;
+	}
+
+	buf_num = ilog2(max_num);
+	bitlen = ALIGN(buf_num, RADIX_BASE * 2);
+
+	shift = 0;
+	while (shift < bitlen) {
+		memset(counters, 0, sizeof(counters));
+
+		for (i = 0; i < num; i++) {
+			buf_num = array[i].count;
+			addr = get4bits(buf_num, shift);
+			counters[addr]++;
+		}
+
+		for (i = 1; i < COUNTERS_SIZE; i++)
+			counters[i] += counters[i - 1];
+
+		for (i = num - 1; i >= 0; i--) {
+			buf_num = array[i].count;
+			addr = get4bits(buf_num, shift);
+			counters[addr]--;
+			new_addr = counters[addr];
+			array_buf[new_addr] = array[i];
+		}
+
+		shift += RADIX_BASE;
+
+		/*
+		 * Normal radix expects to move data from a temporary array, to
+		 * the main one.  But that requires some CPU time. Avoid that
+		 * by doing another sort iteration to original array instead of
+		 * memcpy()
+		 */
+		memset(counters, 0, sizeof(counters));
+
+		for (i = 0; i < num; i ++) {
+			buf_num = array_buf[i].count;
+			addr = get4bits(buf_num, shift);
+			counters[addr]++;
+		}
+
+		for (i = 1; i < COUNTERS_SIZE; i++)
+			counters[i] += counters[i - 1];
+
+		for (i = num - 1; i >= 0; i--) {
+			buf_num = array_buf[i].count;
+			addr = get4bits(buf_num, shift);
+			counters[addr]--;
+			new_addr = counters[addr];
+			array[new_addr] = array_buf[i];
+		}
+
+		shift += RADIX_BASE;
+	}
 }
 
 /*
@@ -1314,7 +1413,7 @@ static int byte_core_set_size(struct heuristic_ws *ws)
 	struct bucket_item *bucket = ws->bucket;
 
 	/* Sort in reverse order */
-	sort(bucket, BUCKET_SIZE, sizeof(*bucket), &bucket_comp_rev, NULL);
+	radix_sort(ws->bucket, ws->bucket_b, BUCKET_SIZE);
 
 	for (i = 0; i < BYTE_CORE_SET_LOW; i++)
 		coreset_sum += bucket[i].count;
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 0868cc554f14..677fa4aa0bd7 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -75,7 +75,7 @@ struct compressed_bio {
 	u32 sums;
 };
 
-void btrfs_init_compress(void);
+void __init btrfs_init_compress(void);
 void btrfs_exit_compress(void);
 
 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
@@ -137,6 +137,8 @@ extern const struct btrfs_compress_op btrfs_zlib_compress;
 extern const struct btrfs_compress_op btrfs_lzo_compress;
 extern const struct btrfs_compress_op btrfs_zstd_compress;
 
+const char* btrfs_compress_type2str(enum btrfs_compression_type type);
+
 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 
 #endif
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 1e74cf826532..b88a79e69ddf 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1807,8 +1807,8 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
  * simple bin_search frontend that does the right thing for
  * leaves vs nodes
  */
-static int bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
-		      int level, int *slot)
+int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
+		     int level, int *slot)
 {
 	if (level == 0)
 		return generic_bin_search(eb,
@@ -1824,12 +1824,6 @@ static int bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
 					  slot);
 }
 
-int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
-		     int level, int *slot)
-{
-	return bin_search(eb, key, level, slot);
-}
-
 static void root_add_used(struct btrfs_root *root, u32 size)
 {
 	spin_lock(&root->accounting_lock);
@@ -2614,7 +2608,7 @@ static int key_search(struct extent_buffer *b, const struct btrfs_key *key,
 		      int level, int *prev_cmp, int *slot)
 {
 	if (*prev_cmp != 0) {
-		*prev_cmp = bin_search(b, key, level, slot);
+		*prev_cmp = btrfs_bin_search(b, key, level, slot);
 		return *prev_cmp;
 	}
 
@@ -2660,17 +2654,29 @@ int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
 }
 
 /*
- * look for key in the tree.  path is filled in with nodes along the way
- * if key is found, we return zero and you can find the item in the leaf
- * level of the path (level 0)
+ * btrfs_search_slot - look for a key in a tree and perform necessary
+ * modifications to preserve tree invariants.
+ *
+ * @trans:	Handle of transaction, used when modifying the tree
+ * @p:		Holds all btree nodes along the search path
+ * @root:	The root node of the tree
+ * @key:	The key we are looking for
+ * @ins_len:	Indicates purpose of search, for inserts it is 1, for
+ *		deletions it's -1. 0 for plain searches
+ * @cow:	boolean should CoW operations be performed. Must always be 1
+ *		when modifying the tree.
+ *
+ * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
+ * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
  *
- * If the key isn't found, the path points to the slot where it should
- * be inserted, and 1 is returned.  If there are other errors during the
- * search a negative error number is returned.
+ * If @key is found, 0 is returned and you can find the item in the leaf level
+ * of the path (level 0)
  *
- * if ins_len > 0, nodes and leaves will be split as we walk down the
- * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
- * possible)
+ * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
+ * points to the slot where it should be inserted
+ *
+ * If an error is encountered while searching the tree a negative error number
+ * is returned
  */
 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		      const struct btrfs_key *key, struct btrfs_path *p,
@@ -2774,6 +2780,8 @@ again:
 		 * contention with the cow code
 		 */
 		if (cow) {
+			bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
+
 			/*
 			 * if we don't really need to cow this block
 			 * then we don't want to set the path blocking,
@@ -2798,9 +2806,13 @@ again:
 			}
 
 			btrfs_set_path_blocking(p);
-			err = btrfs_cow_block(trans, root, b,
-					      p->nodes[level + 1],
-					      p->slots[level + 1], &b);
+			if (last_level)
+				err = btrfs_cow_block(trans, root, b, NULL, 0,
+						      &b);
+			else
+				err = btrfs_cow_block(trans, root, b,
+						      p->nodes[level + 1],
+						      p->slots[level + 1], &b);
 			if (err) {
 				ret = err;
 				goto done;
@@ -5175,7 +5187,7 @@ again:
 	while (1) {
 		nritems = btrfs_header_nritems(cur);
 		level = btrfs_header_level(cur);
-		sret = bin_search(cur, min_key, level, &slot);
+		sret = btrfs_bin_search(cur, min_key, level, &slot);
 
 		/* at the lowest level, we're done, setup the path and exit */
 		if (level == path->lowest_level) {
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 13c260b525a1..1a462ab85c49 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -679,7 +679,6 @@ enum btrfs_orphan_cleanup_state {
 /* used by the raid56 code to lock stripes for read/modify/write */
 struct btrfs_stripe_hash {
 	struct list_head hash_list;
-	wait_queue_head_t wait;
 	spinlock_t lock;
 };
 
@@ -3060,15 +3059,10 @@ struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 					  struct btrfs_path *path, u64 dir,
 					  const char *name, u16 name_len,
 					  int mod);
-int verify_dir_item(struct btrfs_fs_info *fs_info,
-		    struct extent_buffer *leaf, int slot,
-		    struct btrfs_dir_item *dir_item);
 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
 						 struct btrfs_path *path,
 						 const char *name,
 						 int name_len);
-bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
-			     unsigned long start, u16 name_len);
 
 /* orphan.c */
 int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,
@@ -3197,7 +3191,7 @@ int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc);
 struct inode *btrfs_alloc_inode(struct super_block *sb);
 void btrfs_destroy_inode(struct inode *inode);
 int btrfs_drop_inode(struct inode *inode);
-int btrfs_init_cachep(void);
+int __init btrfs_init_cachep(void);
 void btrfs_destroy_cachep(void);
 long btrfs_ioctl_trans_end(struct file *file);
 struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
@@ -3248,7 +3242,7 @@ ssize_t btrfs_dedupe_file_range(struct file *src_file, u64 loff, u64 olen,
 			   struct file *dst_file, u64 dst_loff);
 
 /* file.c */
-int btrfs_auto_defrag_init(void);
+int __init btrfs_auto_defrag_init(void);
 void btrfs_auto_defrag_exit(void);
 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 			   struct btrfs_inode *inode);
@@ -3283,7 +3277,7 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root);
 
 /* sysfs.c */
-int btrfs_init_sysfs(void);
+int __init btrfs_init_sysfs(void);
 void btrfs_exit_sysfs(void);
 int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info);
 void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info);
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index d4db406e2d39..0530f6f2e4ba 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1303,40 +1303,42 @@ static void btrfs_async_run_delayed_root(struct btrfs_work *work)
 	if (!path)
 		goto out;
 
-again:
-	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND / 2)
-		goto free_path;
+	do {
+		if (atomic_read(&delayed_root->items) <
+		    BTRFS_DELAYED_BACKGROUND / 2)
+			break;
 
-	delayed_node = btrfs_first_prepared_delayed_node(delayed_root);
-	if (!delayed_node)
-		goto free_path;
+		delayed_node = btrfs_first_prepared_delayed_node(delayed_root);
+		if (!delayed_node)
+			break;
 
-	path->leave_spinning = 1;
-	root = delayed_node->root;
+		path->leave_spinning = 1;
+		root = delayed_node->root;
 
-	trans = btrfs_join_transaction(root);
-	if (IS_ERR(trans))
-		goto release_path;
+		trans = btrfs_join_transaction(root);
+		if (IS_ERR(trans)) {
+			btrfs_release_path(path);
+			btrfs_release_prepared_delayed_node(delayed_node);
+			total_done++;
+			continue;
+		}
 
-	block_rsv = trans->block_rsv;
-	trans->block_rsv = &root->fs_info->delayed_block_rsv;
+		block_rsv = trans->block_rsv;
+		trans->block_rsv = &root->fs_info->delayed_block_rsv;
 
-	__btrfs_commit_inode_delayed_items(trans, path, delayed_node);
+		__btrfs_commit_inode_delayed_items(trans, path, delayed_node);
 
-	trans->block_rsv = block_rsv;
-	btrfs_end_transaction(trans);
-	btrfs_btree_balance_dirty_nodelay(root->fs_info);
+		trans->block_rsv = block_rsv;
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty_nodelay(root->fs_info);
 
-release_path:
-	btrfs_release_path(path);
-	total_done++;
+		btrfs_release_path(path);
+		btrfs_release_prepared_delayed_node(delayed_node);
+		total_done++;
 
-	btrfs_release_prepared_delayed_node(delayed_node);
-	if ((async_work->nr == 0 && total_done < BTRFS_DELAYED_WRITEBACK) ||
-	    total_done < async_work->nr)
-		goto again;
+	} while ((async_work->nr == 0 && total_done < BTRFS_DELAYED_WRITEBACK)
+		 || total_done < async_work->nr);
 
-free_path:
 	btrfs_free_path(path);
 out:
 	wake_up(&delayed_root->wait);
@@ -1349,10 +1351,6 @@ static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root,
 {
 	struct btrfs_async_delayed_work *async_work;
 
-	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND ||
-	    btrfs_workqueue_normal_congested(fs_info->delayed_workers))
-		return 0;
-
 	async_work = kmalloc(sizeof(*async_work), GFP_NOFS);
 	if (!async_work)
 		return -ENOMEM;
@@ -1388,7 +1386,8 @@ void btrfs_balance_delayed_items(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_delayed_root *delayed_root = fs_info->delayed_root;
 
-	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
+	if ((atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND) ||
+		btrfs_workqueue_normal_congested(fs_info->delayed_workers))
 		return;
 
 	if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) {
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 83be8f9fd906..a1a40cf382e3 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -937,7 +937,7 @@ void btrfs_delayed_ref_exit(void)
 	kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 }
 
-int btrfs_delayed_ref_init(void)
+int __init btrfs_delayed_ref_init(void)
 {
 	btrfs_delayed_ref_head_cachep = kmem_cache_create(
 				"btrfs_delayed_ref_head",
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index a43af432f859..c4f625e5a691 100644
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -203,7 +203,7 @@ extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 
-int btrfs_delayed_ref_init(void);
+int __init btrfs_delayed_ref_init(void);
 void btrfs_delayed_ref_exit(void);
 
 static inline struct btrfs_delayed_extent_op *
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 7c655f9a7a50..7efbc4d1128b 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -172,7 +172,8 @@ no_valid_dev_replace_entry_found:
 				dev_replace->tgtdev->commit_bytes_used =
 					dev_replace->srcdev->commit_bytes_used;
 			}
-			dev_replace->tgtdev->is_tgtdev_for_dev_replace = 1;
+			set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
+				&dev_replace->tgtdev->dev_state);
 			btrfs_init_dev_replace_tgtdev_for_resume(fs_info,
 				dev_replace->tgtdev);
 		}
@@ -304,6 +305,14 @@ void btrfs_after_dev_replace_commit(struct btrfs_fs_info *fs_info)
 		dev_replace->cursor_left_last_write_of_item;
 }
 
+static char* btrfs_dev_name(struct btrfs_device *device)
+{
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
+		return "<missing disk>";
+	else
+		return rcu_str_deref(device->name);
+}
+
 int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 		const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
 		int read_src)
@@ -363,8 +372,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 
 	btrfs_info_in_rcu(fs_info,
 		      "dev_replace from %s (devid %llu) to %s started",
-		      src_device->missing ? "<missing disk>" :
-		        rcu_str_deref(src_device->name),
+		      btrfs_dev_name(src_device),
 		      src_device->devid,
 		      rcu_str_deref(tgt_device->name));
 
@@ -538,8 +546,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	} else {
 		btrfs_err_in_rcu(fs_info,
 				 "btrfs_scrub_dev(%s, %llu, %s) failed %d",
-				 src_device->missing ? "<missing disk>" :
-				 rcu_str_deref(src_device->name),
+				 btrfs_dev_name(src_device),
 				 src_device->devid,
 				 rcu_str_deref(tgt_device->name), scrub_ret);
 		btrfs_dev_replace_unlock(dev_replace, 1);
@@ -557,11 +564,10 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 
 	btrfs_info_in_rcu(fs_info,
 			  "dev_replace from %s (devid %llu) to %s finished",
-			  src_device->missing ? "<missing disk>" :
-			  rcu_str_deref(src_device->name),
+			  btrfs_dev_name(src_device),
 			  src_device->devid,
 			  rcu_str_deref(tgt_device->name));
-	tgt_device->is_tgtdev_for_dev_replace = 0;
+	clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
 	tgt_device->devid = src_device->devid;
 	src_device->devid = BTRFS_DEV_REPLACE_DEVID;
 	memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
@@ -814,12 +820,10 @@ static int btrfs_dev_replace_kthread(void *data)
 	progress = btrfs_dev_replace_progress(fs_info);
 	progress = div_u64(progress, 10);
 	btrfs_info_in_rcu(fs_info,
-		"continuing dev_replace from %s (devid %llu) to %s @%u%%",
-		dev_replace->srcdev->missing ? "<missing disk>"
-			: rcu_str_deref(dev_replace->srcdev->name),
+		"continuing dev_replace from %s (devid %llu) to target %s @%u%%",
+		btrfs_dev_name(dev_replace->srcdev),
 		dev_replace->srcdev->devid,
-		dev_replace->tgtdev ? rcu_str_deref(dev_replace->tgtdev->name)
-			: "<missing target disk>",
+		btrfs_dev_name(dev_replace->tgtdev),
 		(unsigned int)progress);
 
 	btrfs_dev_replace_continue_on_mount(fs_info);
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 41cb9196eaa8..cbe421605cd5 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -403,8 +403,6 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
 			btrfs_dir_data_len(leaf, dir_item);
 		name_ptr = (unsigned long)(dir_item + 1);
 
-		if (verify_dir_item(fs_info, leaf, path->slots[0], dir_item))
-			return NULL;
 		if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 		    memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 			return dir_item;
@@ -450,109 +448,3 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 	}
 	return ret;
 }
-
-int verify_dir_item(struct btrfs_fs_info *fs_info,
-		    struct extent_buffer *leaf,
-		    int slot,
-		    struct btrfs_dir_item *dir_item)
-{
-	u16 namelen = BTRFS_NAME_LEN;
-	int ret;
-	u8 type = btrfs_dir_type(leaf, dir_item);
-
-	if (type >= BTRFS_FT_MAX) {
-		btrfs_crit(fs_info, "invalid dir item type: %d", (int)type);
-		return 1;
-	}
-
-	if (type == BTRFS_FT_XATTR)
-		namelen = XATTR_NAME_MAX;
-
-	if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
-		btrfs_crit(fs_info, "invalid dir item name len: %u",
-		       (unsigned)btrfs_dir_name_len(leaf, dir_item));
-		return 1;
-	}
-
-	namelen = btrfs_dir_name_len(leaf, dir_item);
-	ret = btrfs_is_name_len_valid(leaf, slot,
-				      (unsigned long)(dir_item + 1), namelen);
-	if (!ret)
-		return 1;
-
-	/* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
-	if ((btrfs_dir_data_len(leaf, dir_item) +
-	     btrfs_dir_name_len(leaf, dir_item)) >
-					BTRFS_MAX_XATTR_SIZE(fs_info)) {
-		btrfs_crit(fs_info, "invalid dir item name + data len: %u + %u",
-			   (unsigned)btrfs_dir_name_len(leaf, dir_item),
-			   (unsigned)btrfs_dir_data_len(leaf, dir_item));
-		return 1;
-	}
-
-	return 0;
-}
-
-bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
-			     unsigned long start, u16 name_len)
-{
-	struct btrfs_fs_info *fs_info = leaf->fs_info;
-	struct btrfs_key key;
-	u32 read_start;
-	u32 read_end;
-	u32 item_start;
-	u32 item_end;
-	u32 size;
-	bool ret = true;
-
-	ASSERT(start > BTRFS_LEAF_DATA_OFFSET);
-
-	read_start = start - BTRFS_LEAF_DATA_OFFSET;
-	read_end = read_start + name_len;
-	item_start = btrfs_item_offset_nr(leaf, slot);
-	item_end = btrfs_item_end_nr(leaf, slot);
-
-	btrfs_item_key_to_cpu(leaf, &key, slot);
-
-	switch (key.type) {
-	case BTRFS_DIR_ITEM_KEY:
-	case BTRFS_XATTR_ITEM_KEY:
-	case BTRFS_DIR_INDEX_KEY:
-		size = sizeof(struct btrfs_dir_item);
-		break;
-	case BTRFS_INODE_REF_KEY:
-		size = sizeof(struct btrfs_inode_ref);
-		break;
-	case BTRFS_INODE_EXTREF_KEY:
-		size = sizeof(struct btrfs_inode_extref);
-		break;
-	case BTRFS_ROOT_REF_KEY:
-	case BTRFS_ROOT_BACKREF_KEY:
-		size = sizeof(struct btrfs_root_ref);
-		break;
-	default:
-		ret = false;
-		goto out;
-	}
-
-	if (read_start < item_start) {
-		ret = false;
-		goto out;
-	}
-	if (read_end > item_end) {
-		ret = false;
-		goto out;
-	}
-
-	/* there shall be item(s) before name */
-	if (read_start - item_start < size) {
-		ret = false;
-		goto out;
-	}
-
-out:
-	if (!ret)
-		btrfs_crit(fs_info, "invalid dir item name len: %u",
-			   (unsigned int)name_len);
-	return ret;
-}
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a8ecccfc36de..ed095202942f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -61,7 +61,8 @@
 				 BTRFS_HEADER_FLAG_RELOC |\
 				 BTRFS_SUPER_FLAG_ERROR |\
 				 BTRFS_SUPER_FLAG_SEEDING |\
-				 BTRFS_SUPER_FLAG_METADUMP)
+				 BTRFS_SUPER_FLAG_METADUMP |\
+				 BTRFS_SUPER_FLAG_METADUMP_V2)
 
 static const struct extent_io_ops btree_extent_io_ops;
 static void end_workqueue_fn(struct btrfs_work *work);
@@ -220,7 +221,7 @@ void btrfs_set_buffer_lockdep_class(u64 objectid, struct extent_buffer *eb,
  * extents on the btree inode are pretty simple, there's one extent
  * that covers the entire device
  */
-static struct extent_map *btree_get_extent(struct btrfs_inode *inode,
+struct extent_map *btree_get_extent(struct btrfs_inode *inode,
 		struct page *page, size_t pg_offset, u64 start, u64 len,
 		int create)
 {
@@ -285,7 +286,7 @@ static int csum_tree_block(struct btrfs_fs_info *fs_info,
 			   int verify)
 {
 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
-	char *result = NULL;
+	char result[BTRFS_CSUM_SIZE];
 	unsigned long len;
 	unsigned long cur_len;
 	unsigned long offset = BTRFS_CSUM_SIZE;
@@ -294,7 +295,6 @@ static int csum_tree_block(struct btrfs_fs_info *fs_info,
 	unsigned long map_len;
 	int err;
 	u32 crc = ~(u32)0;
-	unsigned long inline_result;
 
 	len = buf->len - offset;
 	while (len > 0) {
@@ -308,13 +308,7 @@ static int csum_tree_block(struct btrfs_fs_info *fs_info,
 		len -= cur_len;
 		offset += cur_len;
 	}
-	if (csum_size > sizeof(inline_result)) {
-		result = kzalloc(csum_size, GFP_NOFS);
-		if (!result)
-			return -ENOMEM;
-	} else {
-		result = (char *)&inline_result;
-	}
+	memset(result, 0, BTRFS_CSUM_SIZE);
 
 	btrfs_csum_final(crc, result);
 
@@ -329,15 +323,12 @@ static int csum_tree_block(struct btrfs_fs_info *fs_info,
 				"%s checksum verify failed on %llu wanted %X found %X level %d",
 				fs_info->sb->s_id, buf->start,
 				val, found, btrfs_header_level(buf));
-			if (result != (char *)&inline_result)
-				kfree(result);
 			return -EUCLEAN;
 		}
 	} else {
 		write_extent_buffer(buf, result, 0, csum_size);
 	}
-	if (result != (char *)&inline_result)
-		kfree(result);
+
 	return 0;
 }
 
@@ -391,7 +382,7 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,
 		clear_extent_buffer_uptodate(eb);
 out:
 	unlock_extent_cached(io_tree, eb->start, eb->start + eb->len - 1,
-			     &cached_state, GFP_NOFS);
+			     &cached_state);
 	if (need_lock)
 		btrfs_tree_read_unlock_blocking(eb);
 	return ret;
@@ -455,7 +446,7 @@ static int btree_read_extent_buffer_pages(struct btrfs_fs_info *fs_info,
 	io_tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
 	while (1) {
 		ret = read_extent_buffer_pages(io_tree, eb, WAIT_COMPLETE,
-					       btree_get_extent, mirror_num);
+					       mirror_num);
 		if (!ret) {
 			if (!verify_parent_transid(io_tree, eb,
 						   parent_transid, 0))
@@ -1012,7 +1003,7 @@ void readahead_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr)
 	if (IS_ERR(buf))
 		return;
 	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
-				 buf, WAIT_NONE, btree_get_extent, 0);
+				 buf, WAIT_NONE, 0);
 	free_extent_buffer(buf);
 }
 
@@ -1031,7 +1022,7 @@ int reada_tree_block_flagged(struct btrfs_fs_info *fs_info, u64 bytenr,
 	set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags);
 
 	ret = read_extent_buffer_pages(io_tree, buf, WAIT_PAGE_LOCK,
-				       btree_get_extent, mirror_num);
+				       mirror_num);
 	if (ret) {
 		free_extent_buffer(buf);
 		return ret;
@@ -1243,7 +1234,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root;
 	struct btrfs_key key;
 	int ret = 0;
-	uuid_le uuid;
+	uuid_le uuid = NULL_UUID_LE;
 
 	root = btrfs_alloc_root(fs_info, GFP_KERNEL);
 	if (!root)
@@ -1284,7 +1275,8 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	btrfs_set_root_used(&root->root_item, leaf->len);
 	btrfs_set_root_last_snapshot(&root->root_item, 0);
 	btrfs_set_root_dirid(&root->root_item, 0);
-	uuid_le_gen(&uuid);
+	if (is_fstree(objectid))
+		uuid_le_gen(&uuid);
 	memcpy(root->root_item.uuid, uuid.b, BTRFS_UUID_SIZE);
 	root->root_item.drop_level = 0;
 
@@ -2875,7 +2867,7 @@ retry_root_backup:
 		goto fail_sysfs;
 	}
 
-	if (!sb_rdonly(sb) && !btrfs_check_rw_degradable(fs_info)) {
+	if (!sb_rdonly(sb) && !btrfs_check_rw_degradable(fs_info, NULL)) {
 		btrfs_warn(fs_info,
 		"writeable mount is not allowed due to too many missing devices");
 		goto fail_sysfs;
@@ -3357,7 +3349,7 @@ static void write_dev_flush(struct btrfs_device *device)
 	bio->bi_private = &device->flush_wait;
 
 	btrfsic_submit_bio(bio);
-	device->flush_bio_sent = 1;
+	set_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state);
 }
 
 /*
@@ -3367,10 +3359,10 @@ static blk_status_t wait_dev_flush(struct btrfs_device *device)
 {
 	struct bio *bio = device->flush_bio;
 
-	if (!device->flush_bio_sent)
+	if (!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state))
 		return BLK_STS_OK;
 
-	device->flush_bio_sent = 0;
+	clear_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state);
 	wait_for_completion_io(&device->flush_wait);
 
 	return bio->bi_status;
@@ -3378,7 +3370,7 @@ static blk_status_t wait_dev_flush(struct btrfs_device *device)
 
 static int check_barrier_error(struct btrfs_fs_info *fs_info)
 {
-	if (!btrfs_check_rw_degradable(fs_info))
+	if (!btrfs_check_rw_degradable(fs_info, NULL))
 		return -EIO;
 	return 0;
 }
@@ -3394,14 +3386,16 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
 	int errors_wait = 0;
 	blk_status_t ret;
 
+	lockdep_assert_held(&info->fs_devices->device_list_mutex);
 	/* send down all the barriers */
 	head = &info->fs_devices->devices;
-	list_for_each_entry_rcu(dev, head, dev_list) {
-		if (dev->missing)
+	list_for_each_entry(dev, head, dev_list) {
+		if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
 			continue;
 		if (!dev->bdev)
 			continue;
-		if (!dev->in_fs_metadata || !dev->writeable)
+		if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
+		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))
 			continue;
 
 		write_dev_flush(dev);
@@ -3409,14 +3403,15 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
 	}
 
 	/* wait for all the barriers */
-	list_for_each_entry_rcu(dev, head, dev_list) {
-		if (dev->missing)
+	list_for_each_entry(dev, head, dev_list) {
+		if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
 			continue;
 		if (!dev->bdev) {
 			errors_wait++;
 			continue;
 		}
-		if (!dev->in_fs_metadata || !dev->writeable)
+		if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
+		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))
 			continue;
 
 		ret = wait_dev_flush(dev);
@@ -3508,12 +3503,13 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
 		}
 	}
 
-	list_for_each_entry_rcu(dev, head, dev_list) {
+	list_for_each_entry(dev, head, dev_list) {
 		if (!dev->bdev) {
 			total_errors++;
 			continue;
 		}
-		if (!dev->in_fs_metadata || !dev->writeable)
+		if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
+		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))
 			continue;
 
 		btrfs_set_stack_device_generation(dev_item, 0);
@@ -3549,10 +3545,11 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
 	}
 
 	total_errors = 0;
-	list_for_each_entry_rcu(dev, head, dev_list) {
+	list_for_each_entry(dev, head, dev_list) {
 		if (!dev->bdev)
 			continue;
-		if (!dev->in_fs_metadata || !dev->writeable)
+		if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
+		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))
 			continue;
 
 		ret = wait_dev_supers(dev, max_mirrors);
@@ -3910,9 +3907,11 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info)
 		btrfs_err(fs_info, "no valid FS found");
 		ret = -EINVAL;
 	}
-	if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP)
-		btrfs_warn(fs_info, "unrecognized super flag: %llu",
+	if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP) {
+		btrfs_err(fs_info, "unrecognized or unsupported super flag: %llu",
 				btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
+		ret = -EINVAL;
+	}
 	if (btrfs_super_root_level(sb) >= BTRFS_MAX_LEVEL) {
 		btrfs_err(fs_info, "tree_root level too big: %d >= %d",
 				btrfs_super_root_level(sb), BTRFS_MAX_LEVEL);
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 7f7c35d6347a..301151a50ac1 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -149,6 +149,9 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 				     u64 objectid);
 int btree_lock_page_hook(struct page *page, void *data,
 				void (*flush_fn)(void *));
+struct extent_map *btree_get_extent(struct btrfs_inode *inode,
+		struct page *page, size_t pg_offset, u64 start, u64 len,
+		int create);
 int btrfs_get_num_tolerated_disk_barrier_failures(u64 flags);
 int __init btrfs_end_io_wq_init(void);
 void btrfs_end_io_wq_exit(void);
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index 3aeb5770f896..ddaccad469f8 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -283,11 +283,6 @@ static int btrfs_get_name(struct dentry *parent, char *name,
 		name_len = btrfs_inode_ref_name_len(leaf, iref);
 	}
 
-	ret = btrfs_is_name_len_valid(leaf, path->slots[0], name_ptr, name_len);
-	if (!ret) {
-		btrfs_free_path(path);
-		return -EIO;
-	}
 	read_extent_buffer(leaf, name, name_ptr, name_len);
 	btrfs_free_path(path);
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2f4328511ac8..05751a677da4 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2145,7 +2145,10 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
 
 		for (i = 0; i < bbio->num_stripes; i++, stripe++) {
 			u64 bytes;
-			if (!stripe->dev->can_discard)
+			struct request_queue *req_q;
+
+			req_q = bdev_get_queue(stripe->dev->bdev);
+			if (!blk_queue_discard(req_q))
 				continue;
 
 			ret = btrfs_issue_discard(stripe->dev->bdev,
@@ -2894,7 +2897,7 @@ int btrfs_check_space_for_delayed_refs(struct btrfs_trans_handle *trans,
 	struct btrfs_block_rsv *global_rsv;
 	u64 num_heads = trans->transaction->delayed_refs.num_heads_ready;
 	u64 csum_bytes = trans->transaction->delayed_refs.pending_csums;
-	u64 num_dirty_bgs = trans->transaction->num_dirty_bgs;
+	unsigned int num_dirty_bgs = trans->transaction->num_dirty_bgs;
 	u64 num_bytes, num_dirty_bgs_bytes;
 	int ret = 0;
 
@@ -4945,12 +4948,12 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info,
 		bytes = 0;
 	else
 		bytes -= delayed_rsv->size;
+	spin_unlock(&delayed_rsv->lock);
+
 	if (percpu_counter_compare(&space_info->total_bytes_pinned,
 				   bytes) < 0) {
-		spin_unlock(&delayed_rsv->lock);
 		return -ENOSPC;
 	}
-	spin_unlock(&delayed_rsv->lock);
 
 commit:
 	trans = btrfs_join_transaction(fs_info->extent_root);
@@ -5738,8 +5741,8 @@ int btrfs_block_rsv_refill(struct btrfs_root *root,
  * or return if we already have enough space.  This will also handle the resreve
  * tracepoint for the reserved amount.
  */
-int btrfs_inode_rsv_refill(struct btrfs_inode *inode,
-			   enum btrfs_reserve_flush_enum flush)
+static int btrfs_inode_rsv_refill(struct btrfs_inode *inode,
+				  enum btrfs_reserve_flush_enum flush)
 {
 	struct btrfs_root *root = inode->root;
 	struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
@@ -5770,7 +5773,7 @@ int btrfs_inode_rsv_refill(struct btrfs_inode *inode,
  * This is the same as btrfs_block_rsv_release, except that it handles the
  * tracepoint for the reservation.
  */
-void btrfs_inode_rsv_release(struct btrfs_inode *inode)
+static void btrfs_inode_rsv_release(struct btrfs_inode *inode)
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
@@ -9690,7 +9693,7 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
 		 * space to fit our block group in.
 		 */
 		if (device->total_bytes > device->bytes_used + min_free &&
-		    !device->is_tgtdev_for_dev_replace) {
+		    !test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
 			ret = find_free_dev_extent(trans, device, min_free,
 						   &dev_offset, NULL);
 			if (!ret)
@@ -10875,7 +10878,7 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 	*trimmed = 0;
 
 	/* Not writeable = nothing to do. */
-	if (!device->writeable)
+	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
 		return 0;
 
 	/* No free space = nothing to do. */
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d43360b33ef6..dfeb74a0be77 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -21,6 +21,7 @@
 #include "locking.h"
 #include "rcu-string.h"
 #include "backref.h"
+#include "disk-io.h"
 
 static struct kmem_cache *extent_state_cache;
 static struct kmem_cache *extent_buffer_cache;
@@ -109,8 +110,6 @@ struct tree_entry {
 struct extent_page_data {
 	struct bio *bio;
 	struct extent_io_tree *tree;
-	get_extent_t *get_extent;
-
 	/* tells writepage not to lock the state bits for this range
 	 * it still does the unlocking
 	 */
@@ -139,7 +138,8 @@ static void add_extent_changeset(struct extent_state *state, unsigned bits,
 	BUG_ON(ret < 0);
 }
 
-static noinline void flush_write_bio(void *data);
+static void flush_write_bio(struct extent_page_data *epd);
+
 static inline struct btrfs_fs_info *
 tree_fs_info(struct extent_io_tree *tree)
 {
@@ -581,7 +581,7 @@ static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
  *
  * This takes the tree lock, and returns 0 on success and < 0 on error.
  */
-static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			      unsigned bits, int wake, int delete,
 			      struct extent_state **cached_state,
 			      gfp_t mask, struct extent_changeset *changeset)
@@ -1295,10 +1295,10 @@ int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 
 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		     unsigned bits, int wake, int delete,
-		     struct extent_state **cached, gfp_t mask)
+		     struct extent_state **cached)
 {
 	return __clear_extent_bit(tree, start, end, bits, wake, delete,
-				  cached, mask, NULL);
+				  cached, GFP_NOFS, NULL);
 }
 
 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
@@ -1348,7 +1348,7 @@ int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
 	if (err == -EEXIST) {
 		if (failed_start > start)
 			clear_extent_bit(tree, start, failed_start - 1,
-					 EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
+					 EXTENT_LOCKED, 1, 0, NULL);
 		return 0;
 	}
 	return 1;
@@ -1648,7 +1648,7 @@ again:
 			     EXTENT_DELALLOC, 1, cached_state);
 	if (!ret) {
 		unlock_extent_cached(tree, delalloc_start, delalloc_end,
-				     &cached_state, GFP_NOFS);
+				     &cached_state);
 		__unlock_for_delalloc(inode, locked_page,
 			      delalloc_start, delalloc_end);
 		cond_resched();
@@ -1744,7 +1744,7 @@ void extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
 				 unsigned long page_ops)
 {
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, clear_bits, 1, 0,
-			 NULL, GFP_NOFS);
+			 NULL);
 
 	__process_pages_contig(inode->i_mapping, locked_page,
 			       start >> PAGE_SHIFT, end >> PAGE_SHIFT,
@@ -2027,7 +2027,8 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
 	bio->bi_iter.bi_sector = sector;
 	dev = bbio->stripes[bbio->mirror_num - 1].dev;
 	btrfs_put_bbio(bbio);
-	if (!dev || !dev->bdev || !dev->writeable) {
+	if (!dev || !dev->bdev ||
+	    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
 		btrfs_bio_counter_dec(fs_info);
 		bio_put(bio);
 		return -EIO;
@@ -2493,7 +2494,7 @@ endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
 
 	if (uptodate && tree->track_uptodate)
 		set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
-	unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
+	unlock_extent_cached_atomic(tree, start, end, &cached);
 }
 
 /*
@@ -2733,7 +2734,6 @@ static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 	start = page_offset(page) + bvec->bv_offset;
 
 	bio->bi_private = NULL;
-	bio_get(bio);
 
 	if (tree->ops)
 		ret = tree->ops->submit_bio_hook(tree->private_data, bio,
@@ -2741,7 +2741,6 @@ static int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 	else
 		btrfsic_submit_bio(bio);
 
-	bio_put(bio);
 	return blk_status_to_errno(ret);
 }
 
@@ -2943,8 +2942,7 @@ static int __do_readpage(struct extent_io_tree *tree,
 			set_extent_uptodate(tree, cur, cur + iosize - 1,
 					    &cached, GFP_NOFS);
 			unlock_extent_cached(tree, cur,
-					     cur + iosize - 1,
-					     &cached, GFP_NOFS);
+					     cur + iosize - 1, &cached);
 			break;
 		}
 		em = __get_extent_map(inode, page, pg_offset, cur,
@@ -3037,8 +3035,7 @@ static int __do_readpage(struct extent_io_tree *tree,
 			set_extent_uptodate(tree, cur, cur + iosize - 1,
 					    &cached, GFP_NOFS);
 			unlock_extent_cached(tree, cur,
-					     cur + iosize - 1,
-					     &cached, GFP_NOFS);
+					     cur + iosize - 1, &cached);
 			cur = cur + iosize;
 			pg_offset += iosize;
 			continue;
@@ -3093,9 +3090,8 @@ out:
 static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
 					     struct page *pages[], int nr_pages,
 					     u64 start, u64 end,
-					     get_extent_t *get_extent,
 					     struct extent_map **em_cached,
-					     struct bio **bio, int mirror_num,
+					     struct bio **bio,
 					     unsigned long *bio_flags,
 					     u64 *prev_em_start)
 {
@@ -3116,18 +3112,17 @@ static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
 	}
 
 	for (index = 0; index < nr_pages; index++) {
-		__do_readpage(tree, pages[index], get_extent, em_cached, bio,
-			      mirror_num, bio_flags, 0, prev_em_start);
+		__do_readpage(tree, pages[index], btrfs_get_extent, em_cached,
+				bio, 0, bio_flags, 0, prev_em_start);
 		put_page(pages[index]);
 	}
 }
 
 static void __extent_readpages(struct extent_io_tree *tree,
 			       struct page *pages[],
-			       int nr_pages, get_extent_t *get_extent,
+			       int nr_pages,
 			       struct extent_map **em_cached,
-			       struct bio **bio, int mirror_num,
-			       unsigned long *bio_flags,
+			       struct bio **bio, unsigned long *bio_flags,
 			       u64 *prev_em_start)
 {
 	u64 start = 0;
@@ -3147,8 +3142,8 @@ static void __extent_readpages(struct extent_io_tree *tree,
 		} else {
 			__do_contiguous_readpages(tree, &pages[first_index],
 						  index - first_index, start,
-						  end, get_extent, em_cached,
-						  bio, mirror_num, bio_flags,
+						  end, em_cached,
+						  bio, bio_flags,
 						  prev_em_start);
 			start = page_start;
 			end = start + PAGE_SIZE - 1;
@@ -3159,9 +3154,8 @@ static void __extent_readpages(struct extent_io_tree *tree,
 	if (end)
 		__do_contiguous_readpages(tree, &pages[first_index],
 					  index - first_index, start,
-					  end, get_extent, em_cached, bio,
-					  mirror_num, bio_flags,
-					  prev_em_start);
+					  end, em_cached, bio,
+					  bio_flags, prev_em_start);
 }
 
 static int __extent_read_full_page(struct extent_io_tree *tree,
@@ -3376,7 +3370,7 @@ static noinline_for_stack int __extent_writepage_io(struct inode *inode,
 							 page_end, NULL, 1);
 			break;
 		}
-		em = epd->get_extent(BTRFS_I(inode), page, pg_offset, cur,
+		em = btrfs_get_extent(BTRFS_I(inode), page, pg_offset, cur,
 				     end - cur + 1, 1);
 		if (IS_ERR_OR_NULL(em)) {
 			SetPageError(page);
@@ -3459,10 +3453,9 @@ done:
  * and the end_io handler clears the writeback ranges
  */
 static int __extent_writepage(struct page *page, struct writeback_control *wbc,
-			      void *data)
+			      struct extent_page_data *epd)
 {
 	struct inode *inode = page->mapping->host;
-	struct extent_page_data *epd = data;
 	u64 start = page_offset(page);
 	u64 page_end = start + PAGE_SIZE - 1;
 	int ret;
@@ -3896,8 +3889,7 @@ retry:
  * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
  * @mapping: address space structure to write
  * @wbc: subtract the number of written pages from *@wbc->nr_to_write
- * @writepage: function called for each page
- * @data: data passed to writepage function
+ * @data: data passed to __extent_writepage function
  *
  * If a page is already under I/O, write_cache_pages() skips it, even
  * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
@@ -3909,8 +3901,7 @@ retry:
  */
 static int extent_write_cache_pages(struct address_space *mapping,
 			     struct writeback_control *wbc,
-			     writepage_t writepage, void *data,
-			     void (*flush_fn)(void *))
+			     struct extent_page_data *epd)
 {
 	struct inode *inode = mapping->host;
 	int ret = 0;
@@ -3974,7 +3965,7 @@ retry:
 			 * mapping
 			 */
 			if (!trylock_page(page)) {
-				flush_fn(data);
+				flush_write_bio(epd);
 				lock_page(page);
 			}
 
@@ -3985,7 +3976,7 @@ retry:
 
 			if (wbc->sync_mode != WB_SYNC_NONE) {
 				if (PageWriteback(page))
-					flush_fn(data);
+					flush_write_bio(epd);
 				wait_on_page_writeback(page);
 			}
 
@@ -3995,7 +3986,7 @@ retry:
 				continue;
 			}
 
-			ret = (*writepage)(page, wbc, data);
+			ret = __extent_writepage(page, wbc, epd);
 
 			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
 				unlock_page(page);
@@ -4043,7 +4034,7 @@ retry:
 	return ret;
 }
 
-static void flush_epd_write_bio(struct extent_page_data *epd)
+static void flush_write_bio(struct extent_page_data *epd)
 {
 	if (epd->bio) {
 		int ret;
@@ -4054,37 +4045,28 @@ static void flush_epd_write_bio(struct extent_page_data *epd)
 	}
 }
 
-static noinline void flush_write_bio(void *data)
-{
-	struct extent_page_data *epd = data;
-	flush_epd_write_bio(epd);
-}
-
-int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
-			  get_extent_t *get_extent,
-			  struct writeback_control *wbc)
+int extent_write_full_page(struct page *page, struct writeback_control *wbc)
 {
 	int ret;
 	struct extent_page_data epd = {
 		.bio = NULL,
-		.tree = tree,
-		.get_extent = get_extent,
+		.tree = &BTRFS_I(page->mapping->host)->io_tree,
 		.extent_locked = 0,
 		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
 	};
 
 	ret = __extent_writepage(page, wbc, &epd);
 
-	flush_epd_write_bio(&epd);
+	flush_write_bio(&epd);
 	return ret;
 }
 
-int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
-			      u64 start, u64 end, get_extent_t *get_extent,
+int extent_write_locked_range(struct inode *inode, u64 start, u64 end,
 			      int mode)
 {
 	int ret = 0;
 	struct address_space *mapping = inode->i_mapping;
+	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
 	struct page *page;
 	unsigned long nr_pages = (end - start + PAGE_SIZE) >>
 		PAGE_SHIFT;
@@ -4092,7 +4074,6 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
 	struct extent_page_data epd = {
 		.bio = NULL,
 		.tree = tree,
-		.get_extent = get_extent,
 		.extent_locked = 1,
 		.sync_io = mode == WB_SYNC_ALL,
 	};
@@ -4118,34 +4099,30 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
 		start += PAGE_SIZE;
 	}
 
-	flush_epd_write_bio(&epd);
+	flush_write_bio(&epd);
 	return ret;
 }
 
 int extent_writepages(struct extent_io_tree *tree,
 		      struct address_space *mapping,
-		      get_extent_t *get_extent,
 		      struct writeback_control *wbc)
 {
 	int ret = 0;
 	struct extent_page_data epd = {
 		.bio = NULL,
 		.tree = tree,
-		.get_extent = get_extent,
 		.extent_locked = 0,
 		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
 	};
 
-	ret = extent_write_cache_pages(mapping, wbc, __extent_writepage, &epd,
-				       flush_write_bio);
-	flush_epd_write_bio(&epd);
+	ret = extent_write_cache_pages(mapping, wbc, &epd);
+	flush_write_bio(&epd);
 	return ret;
 }
 
 int extent_readpages(struct extent_io_tree *tree,
 		     struct address_space *mapping,
-		     struct list_head *pages, unsigned nr_pages,
-		     get_extent_t get_extent)
+		     struct list_head *pages, unsigned nr_pages)
 {
 	struct bio *bio = NULL;
 	unsigned page_idx;
@@ -4171,13 +4148,13 @@ int extent_readpages(struct extent_io_tree *tree,
 		pagepool[nr++] = page;
 		if (nr < ARRAY_SIZE(pagepool))
 			continue;
-		__extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
-				   &bio, 0, &bio_flags, &prev_em_start);
+		__extent_readpages(tree, pagepool, nr, &em_cached, &bio,
+				&bio_flags, &prev_em_start);
 		nr = 0;
 	}
 	if (nr)
-		__extent_readpages(tree, pagepool, nr, get_extent, &em_cached,
-				   &bio, 0, &bio_flags, &prev_em_start);
+		__extent_readpages(tree, pagepool, nr, &em_cached, &bio,
+				&bio_flags, &prev_em_start);
 
 	if (em_cached)
 		free_extent_map(em_cached);
@@ -4210,7 +4187,7 @@ int extent_invalidatepage(struct extent_io_tree *tree,
 	clear_extent_bit(tree, start, end,
 			 EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
 			 EXTENT_DO_ACCOUNTING,
-			 1, 1, &cached_state, GFP_NOFS);
+			 1, 1, &cached_state);
 	return 0;
 }
 
@@ -4235,9 +4212,9 @@ static int try_release_extent_state(struct extent_map_tree *map,
 		 * at this point we can safely clear everything except the
 		 * locked bit and the nodatasum bit
 		 */
-		ret = clear_extent_bit(tree, start, end,
+		ret = __clear_extent_bit(tree, start, end,
 				 ~(EXTENT_LOCKED | EXTENT_NODATASUM),
-				 0, 0, NULL, mask);
+				 0, 0, NULL, mask, NULL);
 
 		/* if clear_extent_bit failed for enomem reasons,
 		 * we can't allow the release to continue.
@@ -4303,9 +4280,7 @@ int try_release_extent_mapping(struct extent_map_tree *map,
  * This maps until we find something past 'last'
  */
 static struct extent_map *get_extent_skip_holes(struct inode *inode,
-						u64 offset,
-						u64 last,
-						get_extent_t *get_extent)
+						u64 offset, u64 last)
 {
 	u64 sectorsize = btrfs_inode_sectorsize(inode);
 	struct extent_map *em;
@@ -4319,15 +4294,14 @@ static struct extent_map *get_extent_skip_holes(struct inode *inode,
 		if (len == 0)
 			break;
 		len = ALIGN(len, sectorsize);
-		em = get_extent(BTRFS_I(inode), NULL, 0, offset, len, 0);
+		em = btrfs_get_extent_fiemap(BTRFS_I(inode), NULL, 0, offset,
+				len, 0);
 		if (IS_ERR_OR_NULL(em))
 			return em;
 
 		/* if this isn't a hole return it */
-		if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) &&
-		    em->block_start != EXTENT_MAP_HOLE) {
+		if (em->block_start != EXTENT_MAP_HOLE)
 			return em;
-		}
 
 		/* this is a hole, advance to the next extent */
 		offset = extent_map_end(em);
@@ -4452,7 +4426,7 @@ static int emit_last_fiemap_cache(struct btrfs_fs_info *fs_info,
 }
 
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
-		__u64 start, __u64 len, get_extent_t *get_extent)
+		__u64 start, __u64 len)
 {
 	int ret = 0;
 	u64 off = start;
@@ -4534,8 +4508,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len - 1,
 			 &cached_state);
 
-	em = get_extent_skip_holes(inode, start, last_for_get_extent,
-				   get_extent);
+	em = get_extent_skip_holes(inode, start, last_for_get_extent);
 	if (!em)
 		goto out;
 	if (IS_ERR(em)) {
@@ -4623,8 +4596,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		}
 
 		/* now scan forward to see if this is really the last extent. */
-		em = get_extent_skip_holes(inode, off, last_for_get_extent,
-					   get_extent);
+		em = get_extent_skip_holes(inode, off, last_for_get_extent);
 		if (IS_ERR(em)) {
 			ret = PTR_ERR(em);
 			goto out;
@@ -4648,7 +4620,7 @@ out_free:
 out:
 	btrfs_free_path(path);
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, start, start + len - 1,
-			     &cached_state, GFP_NOFS);
+			     &cached_state);
 	return ret;
 }
 
@@ -5264,8 +5236,7 @@ int extent_buffer_uptodate(struct extent_buffer *eb)
 }
 
 int read_extent_buffer_pages(struct extent_io_tree *tree,
-			     struct extent_buffer *eb, int wait,
-			     get_extent_t *get_extent, int mirror_num)
+			     struct extent_buffer *eb, int wait, int mirror_num)
 {
 	unsigned long i;
 	struct page *page;
@@ -5325,7 +5296,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
 
 			ClearPageError(page);
 			err = __extent_read_full_page(tree, page,
-						      get_extent, &bio,
+						      btree_get_extent, &bio,
 						      mirror_num, &bio_flags,
 						      REQ_META);
 			if (err) {
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 20854d63c75b..a7a850abd600 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -300,19 +300,29 @@ int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 		unsigned bits, struct extent_changeset *changeset);
 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		     unsigned bits, int wake, int delete,
-		     struct extent_state **cached, gfp_t mask);
+		     struct extent_state **cached);
+int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		     unsigned bits, int wake, int delete,
+		     struct extent_state **cached, gfp_t mask,
+		     struct extent_changeset *changeset);
 
 static inline int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end)
 {
-	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
-				GFP_NOFS);
+	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL);
 }
 
 static inline int unlock_extent_cached(struct extent_io_tree *tree, u64 start,
-		u64 end, struct extent_state **cached, gfp_t mask)
+		u64 end, struct extent_state **cached)
+{
+	return __clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
+				GFP_NOFS, NULL);
+}
+
+static inline int unlock_extent_cached_atomic(struct extent_io_tree *tree,
+		u64 start, u64 end, struct extent_state **cached)
 {
-	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
-				mask);
+	return __clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
+				GFP_ATOMIC, NULL);
 }
 
 static inline int clear_extent_bits(struct extent_io_tree *tree, u64 start,
@@ -323,8 +333,7 @@ static inline int clear_extent_bits(struct extent_io_tree *tree, u64 start,
 	if (bits & EXTENT_LOCKED)
 		wake = 1;
 
-	return clear_extent_bit(tree, start, end, bits, wake, 0, NULL,
-			GFP_NOFS);
+	return clear_extent_bit(tree, start, end, bits, wake, 0, NULL);
 }
 
 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
@@ -340,10 +349,10 @@ static inline int set_extent_bits(struct extent_io_tree *tree, u64 start,
 }
 
 static inline int clear_extent_uptodate(struct extent_io_tree *tree, u64 start,
-		u64 end, struct extent_state **cached_state, gfp_t mask)
+		u64 end, struct extent_state **cached_state)
 {
-	return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
-				cached_state, mask);
+	return __clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
+				cached_state, GFP_NOFS, NULL);
 }
 
 static inline int set_extent_dirty(struct extent_io_tree *tree, u64 start,
@@ -358,7 +367,7 @@ static inline int clear_extent_dirty(struct extent_io_tree *tree, u64 start,
 {
 	return clear_extent_bit(tree, start, end,
 				EXTENT_DIRTY | EXTENT_DELALLOC |
-				EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
+				EXTENT_DO_ACCOUNTING, 0, 0, NULL);
 }
 
 int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
@@ -401,24 +410,19 @@ int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
 			  struct extent_state **cached_state);
 int extent_invalidatepage(struct extent_io_tree *tree,
 			  struct page *page, unsigned long offset);
-int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
-			  get_extent_t *get_extent,
-			  struct writeback_control *wbc);
-int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
-			      u64 start, u64 end, get_extent_t *get_extent,
+int extent_write_full_page(struct page *page, struct writeback_control *wbc);
+int extent_write_locked_range(struct inode *inode, u64 start, u64 end,
 			      int mode);
 int extent_writepages(struct extent_io_tree *tree,
 		      struct address_space *mapping,
-		      get_extent_t *get_extent,
 		      struct writeback_control *wbc);
 int btree_write_cache_pages(struct address_space *mapping,
 			    struct writeback_control *wbc);
 int extent_readpages(struct extent_io_tree *tree,
 		     struct address_space *mapping,
-		     struct list_head *pages, unsigned nr_pages,
-		     get_extent_t get_extent);
+		     struct list_head *pages, unsigned nr_pages);
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
-		__u64 start, __u64 len, get_extent_t *get_extent);
+		__u64 start, __u64 len);
 void set_page_extent_mapped(struct page *page);
 
 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
@@ -437,7 +441,7 @@ void free_extent_buffer_stale(struct extent_buffer *eb);
 #define WAIT_PAGE_LOCK	2
 int read_extent_buffer_pages(struct extent_io_tree *tree,
 			     struct extent_buffer *eb, int wait,
-			     get_extent_t *get_extent, int mirror_num);
+			     int mirror_num);
 void wait_on_extent_buffer_writeback(struct extent_buffer *eb);
 
 static inline unsigned long num_extent_pages(u64 start, u64 len)
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 2e348fb0b280..d3bd02105d1c 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -454,3 +454,135 @@ void replace_extent_mapping(struct extent_map_tree *tree,
 
 	setup_extent_mapping(tree, new, modified);
 }
+
+static struct extent_map *next_extent_map(struct extent_map *em)
+{
+	struct rb_node *next;
+
+	next = rb_next(&em->rb_node);
+	if (!next)
+		return NULL;
+	return container_of(next, struct extent_map, rb_node);
+}
+
+static struct extent_map *prev_extent_map(struct extent_map *em)
+{
+	struct rb_node *prev;
+
+	prev = rb_prev(&em->rb_node);
+	if (!prev)
+		return NULL;
+	return container_of(prev, struct extent_map, rb_node);
+}
+
+/* helper for btfs_get_extent.  Given an existing extent in the tree,
+ * the existing extent is the nearest extent to map_start,
+ * and an extent that you want to insert, deal with overlap and insert
+ * the best fitted new extent into the tree.
+ */
+static noinline int merge_extent_mapping(struct extent_map_tree *em_tree,
+					 struct extent_map *existing,
+					 struct extent_map *em,
+					 u64 map_start)
+{
+	struct extent_map *prev;
+	struct extent_map *next;
+	u64 start;
+	u64 end;
+	u64 start_diff;
+
+	BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
+
+	if (existing->start > map_start) {
+		next = existing;
+		prev = prev_extent_map(next);
+	} else {
+		prev = existing;
+		next = next_extent_map(prev);
+	}
+
+	start = prev ? extent_map_end(prev) : em->start;
+	start = max_t(u64, start, em->start);
+	end = next ? next->start : extent_map_end(em);
+	end = min_t(u64, end, extent_map_end(em));
+	start_diff = start - em->start;
+	em->start = start;
+	em->len = end - start;
+	if (em->block_start < EXTENT_MAP_LAST_BYTE &&
+	    !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+		em->block_start += start_diff;
+		em->block_len = em->len;
+	}
+	return add_extent_mapping(em_tree, em, 0);
+}
+
+/**
+ * btrfs_add_extent_mapping - add extent mapping into em_tree
+ * @em_tree - the extent tree into which we want to insert the extent mapping
+ * @em_in   - extent we are inserting
+ * @start   - start of the logical range btrfs_get_extent() is requesting
+ * @len     - length of the logical range btrfs_get_extent() is requesting
+ *
+ * Note that @em_in's range may be different from [start, start+len),
+ * but they must be overlapped.
+ *
+ * Insert @em_in into @em_tree. In case there is an overlapping range, handle
+ * the -EEXIST by either:
+ * a) Returning the existing extent in @em_in if @start is within the
+ *    existing em.
+ * b) Merge the existing extent with @em_in passed in.
+ *
+ * Return 0 on success, otherwise -EEXIST.
+ *
+ */
+int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
+			     struct extent_map **em_in, u64 start, u64 len)
+{
+	int ret;
+	struct extent_map *em = *em_in;
+
+	ret = add_extent_mapping(em_tree, em, 0);
+	/* it is possible that someone inserted the extent into the tree
+	 * while we had the lock dropped.  It is also possible that
+	 * an overlapping map exists in the tree
+	 */
+	if (ret == -EEXIST) {
+		struct extent_map *existing;
+
+		ret = 0;
+
+		existing = search_extent_mapping(em_tree, start, len);
+		/*
+		 * existing will always be non-NULL, since there must be
+		 * extent causing the -EEXIST.
+		 */
+		if (start >= existing->start &&
+		    start < extent_map_end(existing)) {
+			free_extent_map(em);
+			*em_in = existing;
+			ret = 0;
+		} else {
+			u64 orig_start = em->start;
+			u64 orig_len = em->len;
+
+			/*
+			 * The existing extent map is the one nearest to
+			 * the [start, start + len) range which overlaps
+			 */
+			ret = merge_extent_mapping(em_tree, existing,
+						   em, start);
+			if (ret) {
+				free_extent_map(em);
+				*em_in = NULL;
+				WARN_ONCE(ret,
+"unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
+					  ret, existing->start, existing->len,
+					  orig_start, orig_len);
+			}
+			free_extent_map(existing);
+		}
+	}
+
+	ASSERT(ret == 0 || ret == -EEXIST);
+	return ret;
+}
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 64365bbc9b16..b29f77bc0732 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -13,7 +13,6 @@
 /* bits for the flags field */
 #define EXTENT_FLAG_PINNED 0 /* this entry not yet on disk, don't free it */
 #define EXTENT_FLAG_COMPRESSED 1
-#define EXTENT_FLAG_VACANCY 2 /* no file extent item found */
 #define EXTENT_FLAG_PREALLOC 3 /* pre-allocated extent */
 #define EXTENT_FLAG_LOGGING 4 /* Logging this extent */
 #define EXTENT_FLAG_FILLING 5 /* Filling in a preallocated extent */
@@ -92,4 +91,6 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len, u64 gen
 void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em);
 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
 					 u64 start, u64 len);
+int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
+			     struct extent_map **em_in, u64 start, u64 len);
 #endif
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index c95d7b2efefb..41ab9073d1d4 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1505,7 +1505,7 @@ lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
 		    ordered->file_offset + ordered->len > start_pos &&
 		    ordered->file_offset <= last_pos) {
 			unlock_extent_cached(&inode->io_tree, start_pos,
-					last_pos, cached_state, GFP_NOFS);
+					last_pos, cached_state);
 			for (i = 0; i < num_pages; i++) {
 				unlock_page(pages[i]);
 				put_page(pages[i]);
@@ -1520,7 +1520,7 @@ lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
 		clear_extent_bit(&inode->io_tree, start_pos, last_pos,
 				 EXTENT_DIRTY | EXTENT_DELALLOC |
 				 EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
-				 0, 0, cached_state, GFP_NOFS);
+				 0, 0, cached_state);
 		*lockstart = start_pos;
 		*lockend = last_pos;
 		ret = 1;
@@ -1756,11 +1756,10 @@ again:
 
 		if (copied > 0)
 			ret = btrfs_dirty_pages(inode, pages, dirty_pages,
-						pos, copied, NULL);
+						pos, copied, &cached_state);
 		if (extents_locked)
 			unlock_extent_cached(&BTRFS_I(inode)->io_tree,
-					     lockstart, lockend, &cached_state,
-					     GFP_NOFS);
+					     lockstart, lockend, &cached_state);
 		btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes);
 		if (ret) {
 			btrfs_drop_pages(pages, num_pages);
@@ -2020,10 +2019,19 @@ int btrfs_release_file(struct inode *inode, struct file *filp)
 static int start_ordered_ops(struct inode *inode, loff_t start, loff_t end)
 {
 	int ret;
+	struct blk_plug plug;
 
+	/*
+	 * This is only called in fsync, which would do synchronous writes, so
+	 * a plug can merge adjacent IOs as much as possible.  Esp. in case of
+	 * multiple disks using raid profile, a large IO can be split to
+	 * several segments of stripe length (currently 64K).
+	 */
+	blk_start_plug(&plug);
 	atomic_inc(&BTRFS_I(inode)->sync_writers);
 	ret = btrfs_fdatawrite_range(inode, start, end);
 	atomic_dec(&BTRFS_I(inode)->sync_writers);
+	blk_finish_plug(&plug);
 
 	return ret;
 }
@@ -2451,6 +2459,46 @@ static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
 	return ret;
 }
 
+static int btrfs_punch_hole_lock_range(struct inode *inode,
+				       const u64 lockstart,
+				       const u64 lockend,
+				       struct extent_state **cached_state)
+{
+	while (1) {
+		struct btrfs_ordered_extent *ordered;
+		int ret;
+
+		truncate_pagecache_range(inode, lockstart, lockend);
+
+		lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
+				 cached_state);
+		ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
+
+		/*
+		 * We need to make sure we have no ordered extents in this range
+		 * and nobody raced in and read a page in this range, if we did
+		 * we need to try again.
+		 */
+		if ((!ordered ||
+		    (ordered->file_offset + ordered->len <= lockstart ||
+		     ordered->file_offset > lockend)) &&
+		     !btrfs_page_exists_in_range(inode, lockstart, lockend)) {
+			if (ordered)
+				btrfs_put_ordered_extent(ordered);
+			break;
+		}
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
+				     lockend, cached_state);
+		ret = btrfs_wait_ordered_range(inode, lockstart,
+					       lockend - lockstart + 1);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
@@ -2567,38 +2615,11 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 		goto out_only_mutex;
 	}
 
-	while (1) {
-		struct btrfs_ordered_extent *ordered;
-
-		truncate_pagecache_range(inode, lockstart, lockend);
-
-		lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
-				 &cached_state);
-		ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
-
-		/*
-		 * We need to make sure we have no ordered extents in this range
-		 * and nobody raced in and read a page in this range, if we did
-		 * we need to try again.
-		 */
-		if ((!ordered ||
-		    (ordered->file_offset + ordered->len <= lockstart ||
-		     ordered->file_offset > lockend)) &&
-		     !btrfs_page_exists_in_range(inode, lockstart, lockend)) {
-			if (ordered)
-				btrfs_put_ordered_extent(ordered);
-			break;
-		}
-		if (ordered)
-			btrfs_put_ordered_extent(ordered);
-		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
-				     lockend, &cached_state, GFP_NOFS);
-		ret = btrfs_wait_ordered_range(inode, lockstart,
-					       lockend - lockstart + 1);
-		if (ret) {
-			inode_unlock(inode);
-			return ret;
-		}
+	ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
+					  &cached_state);
+	if (ret) {
+		inode_unlock(inode);
+		goto out_only_mutex;
 	}
 
 	path = btrfs_alloc_path();
@@ -2743,7 +2764,7 @@ out_free:
 	btrfs_free_block_rsv(fs_info, rsv);
 out:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
-			     &cached_state, GFP_NOFS);
+			     &cached_state);
 out_only_mutex:
 	if (!updated_inode && truncated_block && !ret && !err) {
 		/*
@@ -2807,6 +2828,234 @@ insert:
 	return 0;
 }
 
+static int btrfs_fallocate_update_isize(struct inode *inode,
+					const u64 end,
+					const int mode)
+{
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int ret;
+	int ret2;
+
+	if (mode & FALLOC_FL_KEEP_SIZE || end <= i_size_read(inode))
+		return 0;
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	inode->i_ctime = current_time(inode);
+	i_size_write(inode, end);
+	btrfs_ordered_update_i_size(inode, end, NULL);
+	ret = btrfs_update_inode(trans, root, inode);
+	ret2 = btrfs_end_transaction(trans);
+
+	return ret ? ret : ret2;
+}
+
+enum {
+	RANGE_BOUNDARY_WRITTEN_EXTENT = 0,
+	RANGE_BOUNDARY_PREALLOC_EXTENT = 1,
+	RANGE_BOUNDARY_HOLE = 2,
+};
+
+static int btrfs_zero_range_check_range_boundary(struct inode *inode,
+						 u64 offset)
+{
+	const u64 sectorsize = btrfs_inode_sectorsize(inode);
+	struct extent_map *em;
+	int ret;
+
+	offset = round_down(offset, sectorsize);
+	em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, offset, sectorsize, 0);
+	if (IS_ERR(em))
+		return PTR_ERR(em);
+
+	if (em->block_start == EXTENT_MAP_HOLE)
+		ret = RANGE_BOUNDARY_HOLE;
+	else if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		ret = RANGE_BOUNDARY_PREALLOC_EXTENT;
+	else
+		ret = RANGE_BOUNDARY_WRITTEN_EXTENT;
+
+	free_extent_map(em);
+	return ret;
+}
+
+static int btrfs_zero_range(struct inode *inode,
+			    loff_t offset,
+			    loff_t len,
+			    const int mode)
+{
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	struct extent_map *em;
+	struct extent_changeset *data_reserved = NULL;
+	int ret;
+	u64 alloc_hint = 0;
+	const u64 sectorsize = btrfs_inode_sectorsize(inode);
+	u64 alloc_start = round_down(offset, sectorsize);
+	u64 alloc_end = round_up(offset + len, sectorsize);
+	u64 bytes_to_reserve = 0;
+	bool space_reserved = false;
+
+	inode_dio_wait(inode);
+
+	em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
+			      alloc_start, alloc_end - alloc_start, 0);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out;
+	}
+
+	/*
+	 * Avoid hole punching and extent allocation for some cases. More cases
+	 * could be considered, but these are unlikely common and we keep things
+	 * as simple as possible for now. Also, intentionally, if the target
+	 * range contains one or more prealloc extents together with regular
+	 * extents and holes, we drop all the existing extents and allocate a
+	 * new prealloc extent, so that we get a larger contiguous disk extent.
+	 */
+	if (em->start <= alloc_start &&
+	    test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+		const u64 em_end = em->start + em->len;
+
+		if (em_end >= offset + len) {
+			/*
+			 * The whole range is already a prealloc extent,
+			 * do nothing except updating the inode's i_size if
+			 * needed.
+			 */
+			free_extent_map(em);
+			ret = btrfs_fallocate_update_isize(inode, offset + len,
+							   mode);
+			goto out;
+		}
+		/*
+		 * Part of the range is already a prealloc extent, so operate
+		 * only on the remaining part of the range.
+		 */
+		alloc_start = em_end;
+		ASSERT(IS_ALIGNED(alloc_start, sectorsize));
+		len = offset + len - alloc_start;
+		offset = alloc_start;
+		alloc_hint = em->block_start + em->len;
+	}
+	free_extent_map(em);
+
+	if (BTRFS_BYTES_TO_BLKS(fs_info, offset) ==
+	    BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1)) {
+		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0,
+				      alloc_start, sectorsize, 0);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto out;
+		}
+
+		if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+			free_extent_map(em);
+			ret = btrfs_fallocate_update_isize(inode, offset + len,
+							   mode);
+			goto out;
+		}
+		if (len < sectorsize && em->block_start != EXTENT_MAP_HOLE) {
+			free_extent_map(em);
+			ret = btrfs_truncate_block(inode, offset, len, 0);
+			if (!ret)
+				ret = btrfs_fallocate_update_isize(inode,
+								   offset + len,
+								   mode);
+			return ret;
+		}
+		free_extent_map(em);
+		alloc_start = round_down(offset, sectorsize);
+		alloc_end = alloc_start + sectorsize;
+		goto reserve_space;
+	}
+
+	alloc_start = round_up(offset, sectorsize);
+	alloc_end = round_down(offset + len, sectorsize);
+
+	/*
+	 * For unaligned ranges, check the pages at the boundaries, they might
+	 * map to an extent, in which case we need to partially zero them, or
+	 * they might map to a hole, in which case we need our allocation range
+	 * to cover them.
+	 */
+	if (!IS_ALIGNED(offset, sectorsize)) {
+		ret = btrfs_zero_range_check_range_boundary(inode, offset);
+		if (ret < 0)
+			goto out;
+		if (ret == RANGE_BOUNDARY_HOLE) {
+			alloc_start = round_down(offset, sectorsize);
+			ret = 0;
+		} else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
+			ret = btrfs_truncate_block(inode, offset, 0, 0);
+			if (ret)
+				goto out;
+		} else {
+			ret = 0;
+		}
+	}
+
+	if (!IS_ALIGNED(offset + len, sectorsize)) {
+		ret = btrfs_zero_range_check_range_boundary(inode,
+							    offset + len);
+		if (ret < 0)
+			goto out;
+		if (ret == RANGE_BOUNDARY_HOLE) {
+			alloc_end = round_up(offset + len, sectorsize);
+			ret = 0;
+		} else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
+			ret = btrfs_truncate_block(inode, offset + len, 0, 1);
+			if (ret)
+				goto out;
+		} else {
+			ret = 0;
+		}
+	}
+
+reserve_space:
+	if (alloc_start < alloc_end) {
+		struct extent_state *cached_state = NULL;
+		const u64 lockstart = alloc_start;
+		const u64 lockend = alloc_end - 1;
+
+		bytes_to_reserve = alloc_end - alloc_start;
+		ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
+						      bytes_to_reserve);
+		if (ret < 0)
+			goto out;
+		space_reserved = true;
+		ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
+						alloc_start, bytes_to_reserve);
+		if (ret)
+			goto out;
+		ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
+						  &cached_state);
+		if (ret)
+			goto out;
+		ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
+						alloc_end - alloc_start,
+						i_blocksize(inode),
+						offset + len, &alloc_hint);
+		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
+				     lockend, &cached_state);
+		/* btrfs_prealloc_file_range releases reserved space on error */
+		if (ret) {
+			space_reserved = false;
+			goto out;
+		}
+	}
+	ret = btrfs_fallocate_update_isize(inode, offset + len, mode);
+ out:
+	if (ret && space_reserved)
+		btrfs_free_reserved_data_space(inode, data_reserved,
+					       alloc_start, bytes_to_reserve);
+	extent_changeset_free(data_reserved);
+
+	return ret;
+}
+
 static long btrfs_fallocate(struct file *file, int mode,
 			    loff_t offset, loff_t len)
 {
@@ -2832,7 +3081,8 @@ static long btrfs_fallocate(struct file *file, int mode,
 	cur_offset = alloc_start;
 
 	/* Make sure we aren't being give some crap mode */
-	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
+		     FALLOC_FL_ZERO_RANGE))
 		return -EOPNOTSUPP;
 
 	if (mode & FALLOC_FL_PUNCH_HOLE)
@@ -2843,10 +3093,12 @@ static long btrfs_fallocate(struct file *file, int mode,
 	 *
 	 * For qgroup space, it will be checked later.
 	 */
-	ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
-			alloc_end - alloc_start);
-	if (ret < 0)
-		return ret;
+	if (!(mode & FALLOC_FL_ZERO_RANGE)) {
+		ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
+						      alloc_end - alloc_start);
+		if (ret < 0)
+			return ret;
+	}
 
 	inode_lock(inode);
 
@@ -2888,6 +3140,12 @@ static long btrfs_fallocate(struct file *file, int mode,
 	if (ret)
 		goto out;
 
+	if (mode & FALLOC_FL_ZERO_RANGE) {
+		ret = btrfs_zero_range(inode, offset, len, mode);
+		inode_unlock(inode);
+		return ret;
+	}
+
 	locked_end = alloc_end - 1;
 	while (1) {
 		struct btrfs_ordered_extent *ordered;
@@ -2897,15 +3155,15 @@ static long btrfs_fallocate(struct file *file, int mode,
 		 */
 		lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
 				 locked_end, &cached_state);
-		ordered = btrfs_lookup_first_ordered_extent(inode,
-							    alloc_end - 1);
+		ordered = btrfs_lookup_first_ordered_extent(inode, locked_end);
+
 		if (ordered &&
 		    ordered->file_offset + ordered->len > alloc_start &&
 		    ordered->file_offset < alloc_end) {
 			btrfs_put_ordered_extent(ordered);
 			unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 					     alloc_start, locked_end,
-					     &cached_state, GFP_KERNEL);
+					     &cached_state);
 			/*
 			 * we can't wait on the range with the transaction
 			 * running or with the extent lock held
@@ -2923,7 +3181,7 @@ static long btrfs_fallocate(struct file *file, int mode,
 
 	/* First, check if we exceed the qgroup limit */
 	INIT_LIST_HEAD(&reserve_list);
-	while (1) {
+	while (cur_offset < alloc_end) {
 		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, cur_offset,
 				      alloc_end - cur_offset, 0);
 		if (IS_ERR(em)) {
@@ -2959,8 +3217,6 @@ static long btrfs_fallocate(struct file *file, int mode,
 		}
 		free_extent_map(em);
 		cur_offset = last_byte;
-		if (cur_offset >= alloc_end)
-			break;
 	}
 
 	/*
@@ -2983,37 +3239,18 @@ static long btrfs_fallocate(struct file *file, int mode,
 	if (ret < 0)
 		goto out_unlock;
 
-	if (actual_end > inode->i_size &&
-	    !(mode & FALLOC_FL_KEEP_SIZE)) {
-		struct btrfs_trans_handle *trans;
-		struct btrfs_root *root = BTRFS_I(inode)->root;
-
-		/*
-		 * We didn't need to allocate any more space, but we
-		 * still extended the size of the file so we need to
-		 * update i_size and the inode item.
-		 */
-		trans = btrfs_start_transaction(root, 1);
-		if (IS_ERR(trans)) {
-			ret = PTR_ERR(trans);
-		} else {
-			inode->i_ctime = current_time(inode);
-			i_size_write(inode, actual_end);
-			btrfs_ordered_update_i_size(inode, actual_end, NULL);
-			ret = btrfs_update_inode(trans, root, inode);
-			if (ret)
-				btrfs_end_transaction(trans);
-			else
-				ret = btrfs_end_transaction(trans);
-		}
-	}
+	/*
+	 * We didn't need to allocate any more space, but we still extended the
+	 * size of the file so we need to update i_size and the inode item.
+	 */
+	ret = btrfs_fallocate_update_isize(inode, actual_end, mode);
 out_unlock:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
-			     &cached_state, GFP_KERNEL);
+			     &cached_state);
 out:
 	inode_unlock(inode);
 	/* Let go of our reservation. */
-	if (ret != 0)
+	if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE))
 		btrfs_free_reserved_data_space(inode, data_reserved,
 				alloc_start, alloc_end - cur_offset);
 	extent_changeset_free(data_reserved);
@@ -3082,7 +3319,7 @@ static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
 			*offset = min_t(loff_t, start, inode->i_size);
 	}
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
-			     &cached_state, GFP_NOFS);
+			     &cached_state);
 	return ret;
 }
 
@@ -3146,7 +3383,7 @@ void btrfs_auto_defrag_exit(void)
 	kmem_cache_destroy(btrfs_inode_defrag_cachep);
 }
 
-int btrfs_auto_defrag_init(void)
+int __init btrfs_auto_defrag_init(void)
 {
 	btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
 					sizeof(struct inode_defrag), 0,
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 4426d1c73e50..014f3c090231 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -993,8 +993,7 @@ update_cache_item(struct btrfs_trans_handle *trans,
 	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 	if (ret < 0) {
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
-				 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
-				 GFP_NOFS);
+				 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL);
 		goto fail;
 	}
 	leaf = path->nodes[0];
@@ -1008,7 +1007,7 @@ update_cache_item(struct btrfs_trans_handle *trans,
 			clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
 					 inode->i_size - 1,
 					 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
-					 NULL, GFP_NOFS);
+					 NULL);
 			btrfs_release_path(path);
 			goto fail;
 		}
@@ -1105,8 +1104,7 @@ static int flush_dirty_cache(struct inode *inode)
 	ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
 	if (ret)
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
-				 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
-				 GFP_NOFS);
+				 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL);
 
 	return ret;
 }
@@ -1127,8 +1125,7 @@ cleanup_write_cache_enospc(struct inode *inode,
 {
 	io_ctl_drop_pages(io_ctl);
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
-			     i_size_read(inode) - 1, cached_state,
-			     GFP_NOFS);
+			     i_size_read(inode) - 1, cached_state);
 }
 
 static int __btrfs_wait_cache_io(struct btrfs_root *root,
@@ -1322,7 +1319,7 @@ static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 	io_ctl_drop_pages(io_ctl);
 
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
-			     i_size_read(inode) - 1, &cached_state, GFP_NOFS);
+			     i_size_read(inode) - 1, &cached_state);
 
 	/*
 	 * at this point the pages are under IO and we're happy,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 734b37d9d459..53ca025655fc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -537,9 +537,14 @@ again:
 		 *
 		 * If the compression fails for any reason, we set the pages
 		 * dirty again later on.
+		 *
+		 * Note that the remaining part is redirtied, the start pointer
+		 * has moved, the end is the original one.
 		 */
-		extent_range_clear_dirty_for_io(inode, start, end);
-		redirty = 1;
+		if (!redirty) {
+			extent_range_clear_dirty_for_io(inode, start, end);
+			redirty = 1;
+		}
 
 		/* Compression level is applied here and only here */
 		ret = btrfs_compress_pages(
@@ -766,11 +771,10 @@ retry:
 			 * all those pages down to the drive.
 			 */
 			if (!page_started && !ret)
-				extent_write_locked_range(io_tree,
-						  inode, async_extent->start,
+				extent_write_locked_range(inode,
+						  async_extent->start,
 						  async_extent->start +
 						  async_extent->ram_size - 1,
-						  btrfs_get_extent,
 						  WB_SYNC_ALL);
 			else if (ret)
 				unlock_page(async_cow->locked_page);
@@ -1204,7 +1208,7 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
 	u64 cur_end;
 
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, EXTENT_LOCKED,
-			 1, 0, NULL, GFP_NOFS);
+			 1, 0, NULL);
 	while (start < end) {
 		async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
 		BUG_ON(!async_cow); /* -ENOMEM */
@@ -1952,7 +1956,21 @@ static blk_status_t __btrfs_submit_bio_done(void *private_data, struct bio *bio,
 
 /*
  * extent_io.c submission hook. This does the right thing for csum calculation
- * on write, or reading the csums from the tree before a read
+ * on write, or reading the csums from the tree before a read.
+ *
+ * Rules about async/sync submit,
+ * a) read:				sync submit
+ *
+ * b) write without checksum:		sync submit
+ *
+ * c) write with checksum:
+ *    c-1) if bio is issued by fsync:	sync submit
+ *         (sync_writers != 0)
+ *
+ *    c-2) if root is reloc root:	sync submit
+ *         (only in case of buffered IO)
+ *
+ *    c-3) otherwise:			async submit
  */
 static blk_status_t btrfs_submit_bio_hook(void *private_data, struct bio *bio,
 				 int mirror_num, unsigned long bio_flags,
@@ -2024,10 +2042,10 @@ static noinline int add_pending_csums(struct btrfs_trans_handle *trans,
 	struct btrfs_ordered_sum *sum;
 
 	list_for_each_entry(sum, list, list) {
-		trans->adding_csums = 1;
+		trans->adding_csums = true;
 		btrfs_csum_file_blocks(trans,
 		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
-		trans->adding_csums = 0;
+		trans->adding_csums = false;
 	}
 	return 0;
 }
@@ -2083,7 +2101,7 @@ again:
 					PAGE_SIZE);
 	if (ordered) {
 		unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start,
-				     page_end, &cached_state, GFP_NOFS);
+				     page_end, &cached_state);
 		unlock_page(page);
 		btrfs_start_ordered_extent(inode, ordered, 1);
 		btrfs_put_ordered_extent(ordered);
@@ -2099,14 +2117,21 @@ again:
 		goto out;
 	 }
 
-	btrfs_set_extent_delalloc(inode, page_start, page_end, 0, &cached_state,
-				  0);
+	ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
+					&cached_state, 0);
+	if (ret) {
+		mapping_set_error(page->mapping, ret);
+		end_extent_writepage(page, ret, page_start, page_end);
+		ClearPageChecked(page);
+		goto out;
+	}
+
 	ClearPageChecked(page);
 	set_page_dirty(page);
 	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
 out:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start, page_end,
-			     &cached_state, GFP_NOFS);
+			     &cached_state);
 out_page:
 	unlock_page(page);
 	put_page(page);
@@ -2698,7 +2723,7 @@ out_free_path:
 	btrfs_end_transaction(trans);
 out_unlock:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start, lock_end,
-			     &cached, GFP_NOFS);
+			     &cached);
 	iput(inode);
 	return ret;
 }
@@ -2987,7 +3012,7 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 
 		clear_extent_bit(io_tree, ordered_extent->file_offset,
 			ordered_extent->file_offset + ordered_extent->len - 1,
-			EXTENT_DEFRAG, 0, 0, &cached_state, GFP_NOFS);
+			EXTENT_DEFRAG, 0, 0, &cached_state);
 	}
 
 	if (nolock)
@@ -3057,7 +3082,7 @@ out:
 				 ordered_extent->len - 1,
 				 clear_bits,
 				 (clear_bits & EXTENT_LOCKED) ? 1 : 0,
-				 0, &cached_state, GFP_NOFS);
+				 0, &cached_state);
 	}
 
 	if (trans)
@@ -3071,7 +3096,7 @@ out:
 		else
 			start = ordered_extent->file_offset;
 		end = ordered_extent->file_offset + ordered_extent->len - 1;
-		clear_extent_uptodate(io_tree, start, end, NULL, GFP_NOFS);
+		clear_extent_uptodate(io_tree, start, end, NULL);
 
 		/* Drop the cache for the part of the extent we didn't write. */
 		btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
@@ -4747,8 +4772,8 @@ int btrfs_truncate_block(struct inode *inode, loff_t from, loff_t len,
 	u64 block_start;
 	u64 block_end;
 
-	if ((offset & (blocksize - 1)) == 0 &&
-	    (!len || ((len & (blocksize - 1)) == 0)))
+	if (IS_ALIGNED(offset, blocksize) &&
+	    (!len || IS_ALIGNED(len, blocksize)))
 		goto out;
 
 	block_start = round_down(from, blocksize);
@@ -4790,7 +4815,7 @@ again:
 	ordered = btrfs_lookup_ordered_extent(inode, block_start);
 	if (ordered) {
 		unlock_extent_cached(io_tree, block_start, block_end,
-				     &cached_state, GFP_NOFS);
+				     &cached_state);
 		unlock_page(page);
 		put_page(page);
 		btrfs_start_ordered_extent(inode, ordered, 1);
@@ -4801,13 +4826,13 @@ again:
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, block_start, block_end,
 			  EXTENT_DIRTY | EXTENT_DELALLOC |
 			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
-			  0, 0, &cached_state, GFP_NOFS);
+			  0, 0, &cached_state);
 
 	ret = btrfs_set_extent_delalloc(inode, block_start, block_end, 0,
 					&cached_state, 0);
 	if (ret) {
 		unlock_extent_cached(io_tree, block_start, block_end,
-				     &cached_state, GFP_NOFS);
+				     &cached_state);
 		goto out_unlock;
 	}
 
@@ -4826,8 +4851,7 @@ again:
 	}
 	ClearPageChecked(page);
 	set_page_dirty(page);
-	unlock_extent_cached(io_tree, block_start, block_end, &cached_state,
-			     GFP_NOFS);
+	unlock_extent_cached(io_tree, block_start, block_end, &cached_state);
 
 out_unlock:
 	if (ret)
@@ -4928,7 +4952,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
 		if (!ordered)
 			break;
 		unlock_extent_cached(io_tree, hole_start, block_end - 1,
-				     &cached_state, GFP_NOFS);
+				     &cached_state);
 		btrfs_start_ordered_extent(inode, ordered, 1);
 		btrfs_put_ordered_extent(ordered);
 	}
@@ -4993,8 +5017,7 @@ next:
 			break;
 	}
 	free_extent_map(em);
-	unlock_extent_cached(io_tree, hole_start, block_end - 1, &cached_state,
-			     GFP_NOFS);
+	unlock_extent_cached(io_tree, hole_start, block_end - 1, &cached_state);
 	return err;
 }
 
@@ -5237,8 +5260,7 @@ static void evict_inode_truncate_pages(struct inode *inode)
 		clear_extent_bit(io_tree, start, end,
 				 EXTENT_LOCKED | EXTENT_DIRTY |
 				 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
-				 EXTENT_DEFRAG, 1, 1,
-				 &cached_state, GFP_NOFS);
+				 EXTENT_DEFRAG, 1, 1, &cached_state);
 
 		cond_resched();
 		spin_lock(&io_tree->lock);
@@ -5897,7 +5919,6 @@ static int btrfs_filldir(void *addr, int entries, struct dir_context *ctx)
 static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct inode *inode = file_inode(file);
-	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_file_private *private = file->private_data;
 	struct btrfs_dir_item *di;
@@ -5965,9 +5986,6 @@ again:
 		if (btrfs_should_delete_dir_index(&del_list, found_key.offset))
 			goto next;
 		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
-		if (verify_dir_item(fs_info, leaf, slot, di))
-			goto next;
-
 		name_len = btrfs_dir_name_len(leaf, di);
 		if ((total_len + sizeof(struct dir_entry) + name_len) >=
 		    PAGE_SIZE) {
@@ -6301,7 +6319,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 	}
 	/*
 	 * index_cnt is ignored for everything but a dir,
-	 * btrfs_get_inode_index_count has an explanation for the magic
+	 * btrfs_set_inode_index_count has an explanation for the magic
 	 * number
 	 */
 	BTRFS_I(inode)->index_cnt = 2;
@@ -6564,7 +6582,6 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
 
 out_unlock:
 	btrfs_end_transaction(trans);
-	btrfs_balance_delayed_items(fs_info);
 	btrfs_btree_balance_dirty(fs_info);
 	if (drop_inode) {
 		inode_dec_link_count(inode);
@@ -6645,7 +6662,6 @@ out_unlock:
 		inode_dec_link_count(inode);
 		iput(inode);
 	}
-	btrfs_balance_delayed_items(fs_info);
 	btrfs_btree_balance_dirty(fs_info);
 	return err;
 
@@ -6720,7 +6736,6 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 		btrfs_log_new_name(trans, BTRFS_I(inode), NULL, parent);
 	}
 
-	btrfs_balance_delayed_items(fs_info);
 fail:
 	if (trans)
 		btrfs_end_transaction(trans);
@@ -6798,7 +6813,6 @@ out_fail:
 		inode_dec_link_count(inode);
 		iput(inode);
 	}
-	btrfs_balance_delayed_items(fs_info);
 	btrfs_btree_balance_dirty(fs_info);
 	return err;
 
@@ -6807,68 +6821,6 @@ out_fail_inode:
 	goto out_fail;
 }
 
-/* Find next extent map of a given extent map, caller needs to ensure locks */
-static struct extent_map *next_extent_map(struct extent_map *em)
-{
-	struct rb_node *next;
-
-	next = rb_next(&em->rb_node);
-	if (!next)
-		return NULL;
-	return container_of(next, struct extent_map, rb_node);
-}
-
-static struct extent_map *prev_extent_map(struct extent_map *em)
-{
-	struct rb_node *prev;
-
-	prev = rb_prev(&em->rb_node);
-	if (!prev)
-		return NULL;
-	return container_of(prev, struct extent_map, rb_node);
-}
-
-/* helper for btfs_get_extent.  Given an existing extent in the tree,
- * the existing extent is the nearest extent to map_start,
- * and an extent that you want to insert, deal with overlap and insert
- * the best fitted new extent into the tree.
- */
-static int merge_extent_mapping(struct extent_map_tree *em_tree,
-				struct extent_map *existing,
-				struct extent_map *em,
-				u64 map_start)
-{
-	struct extent_map *prev;
-	struct extent_map *next;
-	u64 start;
-	u64 end;
-	u64 start_diff;
-
-	BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
-
-	if (existing->start > map_start) {
-		next = existing;
-		prev = prev_extent_map(next);
-	} else {
-		prev = existing;
-		next = next_extent_map(prev);
-	}
-
-	start = prev ? extent_map_end(prev) : em->start;
-	start = max_t(u64, start, em->start);
-	end = next ? next->start : extent_map_end(em);
-	end = min_t(u64, end, extent_map_end(em));
-	start_diff = start - em->start;
-	em->start = start;
-	em->len = end - start;
-	if (em->block_start < EXTENT_MAP_LAST_BYTE &&
-	    !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
-		em->block_start += start_diff;
-		em->block_len -= start_diff;
-	}
-	return add_extent_mapping(em_tree, em, 0);
-}
-
 static noinline int uncompress_inline(struct btrfs_path *path,
 				      struct page *page,
 				      size_t pg_offset, u64 extent_offset,
@@ -6943,10 +6895,8 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
 	struct extent_map *em = NULL;
 	struct extent_map_tree *em_tree = &inode->extent_tree;
 	struct extent_io_tree *io_tree = &inode->io_tree;
-	struct btrfs_trans_handle *trans = NULL;
 	const bool new_inline = !page || create;
 
-again:
 	read_lock(&em_tree->lock);
 	em = lookup_extent_mapping(em_tree, start, len);
 	if (em)
@@ -6985,8 +6935,7 @@ again:
 		path->reada = READA_FORWARD;
 	}
 
-	ret = btrfs_lookup_file_extent(trans, root, path,
-				       objectid, start, trans != NULL);
+	ret = btrfs_lookup_file_extent(NULL, root, path, objectid, start, 0);
 	if (ret < 0) {
 		err = ret;
 		goto out;
@@ -7087,7 +7036,7 @@ next:
 		em->orig_block_len = em->len;
 		em->orig_start = em->start;
 		ptr = btrfs_file_extent_inline_start(item) + extent_offset;
-		if (create == 0 && !PageUptodate(page)) {
+		if (!PageUptodate(page)) {
 			if (btrfs_file_extent_compression(leaf, item) !=
 			    BTRFS_COMPRESS_NONE) {
 				ret = uncompress_inline(path, page, pg_offset,
@@ -7108,25 +7057,6 @@ next:
 				kunmap(page);
 			}
 			flush_dcache_page(page);
-		} else if (create && PageUptodate(page)) {
-			BUG();
-			if (!trans) {
-				kunmap(page);
-				free_extent_map(em);
-				em = NULL;
-
-				btrfs_release_path(path);
-				trans = btrfs_join_transaction(root);
-
-				if (IS_ERR(trans))
-					return ERR_CAST(trans);
-				goto again;
-			}
-			map = kmap(page);
-			write_extent_buffer(leaf, map + pg_offset, ptr,
-					    copy_size);
-			kunmap(page);
-			btrfs_mark_buffer_dirty(leaf);
 		}
 		set_extent_uptodate(io_tree, em->start,
 				    extent_map_end(em) - 1, NULL, GFP_NOFS);
@@ -7138,7 +7068,6 @@ not_found:
 	em->len = len;
 not_found_em:
 	em->block_start = EXTENT_MAP_HOLE;
-	set_bit(EXTENT_FLAG_VACANCY, &em->flags);
 insert:
 	btrfs_release_path(path);
 	if (em->start > start || extent_map_end(em) <= start) {
@@ -7151,62 +7080,13 @@ insert:
 
 	err = 0;
 	write_lock(&em_tree->lock);
-	ret = add_extent_mapping(em_tree, em, 0);
-	/* it is possible that someone inserted the extent into the tree
-	 * while we had the lock dropped.  It is also possible that
-	 * an overlapping map exists in the tree
-	 */
-	if (ret == -EEXIST) {
-		struct extent_map *existing;
-
-		ret = 0;
-
-		existing = search_extent_mapping(em_tree, start, len);
-		/*
-		 * existing will always be non-NULL, since there must be
-		 * extent causing the -EEXIST.
-		 */
-		if (existing->start == em->start &&
-		    extent_map_end(existing) >= extent_map_end(em) &&
-		    em->block_start == existing->block_start) {
-			/*
-			 * The existing extent map already encompasses the
-			 * entire extent map we tried to add.
-			 */
-			free_extent_map(em);
-			em = existing;
-			err = 0;
-
-		} else if (start >= extent_map_end(existing) ||
-		    start <= existing->start) {
-			/*
-			 * The existing extent map is the one nearest to
-			 * the [start, start + len) range which overlaps
-			 */
-			err = merge_extent_mapping(em_tree, existing,
-						   em, start);
-			free_extent_map(existing);
-			if (err) {
-				free_extent_map(em);
-				em = NULL;
-			}
-		} else {
-			free_extent_map(em);
-			em = existing;
-			err = 0;
-		}
-	}
+	err = btrfs_add_extent_mapping(em_tree, &em, start, len);
 	write_unlock(&em_tree->lock);
 out:
 
 	trace_btrfs_get_extent(root, inode, em);
 
 	btrfs_free_path(path);
-	if (trans) {
-		ret = btrfs_end_transaction(trans);
-		if (!err)
-			err = ret;
-	}
 	if (err) {
 		free_extent_map(em);
 		return ERR_PTR(err);
@@ -7328,7 +7208,7 @@ struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
 			em->block_start = EXTENT_MAP_DELALLOC;
 			em->block_len = found;
 		}
-	} else if (hole_em) {
+	} else {
 		return hole_em;
 	}
 out:
@@ -7645,7 +7525,7 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
 			break;
 
 		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
-				     cached_state, GFP_NOFS);
+				     cached_state);
 
 		if (ordered) {
 			/*
@@ -7930,7 +7810,7 @@ unlock:
 	if (lockstart < lockend) {
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
 				 lockend, unlock_bits, 1, 0,
-				 &cached_state, GFP_NOFS);
+				 &cached_state);
 	} else {
 		free_extent_state(cached_state);
 	}
@@ -7941,7 +7821,7 @@ unlock:
 
 unlock_err:
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend,
-			 unlock_bits, 1, 0, &cached_state, GFP_NOFS);
+			 unlock_bits, 1, 0, &cached_state);
 err:
 	if (dio_data)
 		current->journal_info = dio_data;
@@ -7957,15 +7837,12 @@ static inline blk_status_t submit_dio_repair_bio(struct inode *inode,
 
 	BUG_ON(bio_op(bio) == REQ_OP_WRITE);
 
-	bio_get(bio);
-
 	ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DIO_REPAIR);
 	if (ret)
-		goto err;
+		return ret;
 
 	ret = btrfs_map_bio(fs_info, bio, mirror_num, 0);
-err:
-	bio_put(bio);
+
 	return ret;
 }
 
@@ -8466,11 +8343,10 @@ __btrfs_submit_dio_bio(struct bio *bio, struct inode *inode, u64 file_offset,
 	bool write = bio_op(bio) == REQ_OP_WRITE;
 	blk_status_t ret;
 
+	/* Check btrfs_submit_bio_hook() for rules about async submit. */
 	if (async_submit)
 		async_submit = !atomic_read(&BTRFS_I(inode)->sync_writers);
 
-	bio_get(bio);
-
 	if (!write) {
 		ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
 		if (ret)
@@ -8503,7 +8379,6 @@ __btrfs_submit_dio_bio(struct bio *bio, struct inode *inode, u64 file_offset,
 map:
 	ret = btrfs_map_bio(fs_info, bio, 0, 0);
 err:
-	bio_put(bio);
 	return ret;
 }
 
@@ -8860,7 +8735,7 @@ static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	if (ret)
 		return ret;
 
-	return extent_fiemap(inode, fieinfo, start, len, btrfs_get_extent_fiemap);
+	return extent_fiemap(inode, fieinfo, start, len);
 }
 
 int btrfs_readpage(struct file *file, struct page *page)
@@ -8872,7 +8747,6 @@ int btrfs_readpage(struct file *file, struct page *page)
 
 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 {
-	struct extent_io_tree *tree;
 	struct inode *inode = page->mapping->host;
 	int ret;
 
@@ -8891,8 +8765,7 @@ static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 		redirty_page_for_writepage(wbc, page);
 		return AOP_WRITEPAGE_ACTIVATE;
 	}
-	tree = &BTRFS_I(page->mapping->host)->io_tree;
-	ret = extent_write_full_page(tree, page, btrfs_get_extent, wbc);
+	ret = extent_write_full_page(page, wbc);
 	btrfs_add_delayed_iput(inode);
 	return ret;
 }
@@ -8903,7 +8776,7 @@ static int btrfs_writepages(struct address_space *mapping,
 	struct extent_io_tree *tree;
 
 	tree = &BTRFS_I(mapping->host)->io_tree;
-	return extent_writepages(tree, mapping, btrfs_get_extent, wbc);
+	return extent_writepages(tree, mapping, wbc);
 }
 
 static int
@@ -8912,8 +8785,7 @@ btrfs_readpages(struct file *file, struct address_space *mapping,
 {
 	struct extent_io_tree *tree;
 	tree = &BTRFS_I(mapping->host)->io_tree;
-	return extent_readpages(tree, mapping, pages, nr_pages,
-				btrfs_get_extent);
+	return extent_readpages(tree, mapping, pages, nr_pages);
 }
 static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
 {
@@ -8984,8 +8856,7 @@ again:
 					 EXTENT_DIRTY | EXTENT_DELALLOC |
 					 EXTENT_DELALLOC_NEW |
 					 EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
-					 EXTENT_DEFRAG, 1, 0, &cached_state,
-					 GFP_NOFS);
+					 EXTENT_DEFRAG, 1, 0, &cached_state);
 		/*
 		 * whoever cleared the private bit is responsible
 		 * for the finish_ordered_io
@@ -9042,7 +8913,7 @@ again:
 				 EXTENT_LOCKED | EXTENT_DIRTY |
 				 EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
 				 EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 1, 1,
-				 &cached_state, GFP_NOFS);
+				 &cached_state);
 
 		__btrfs_releasepage(page, GFP_NOFS);
 	}
@@ -9143,7 +9014,7 @@ again:
 			PAGE_SIZE);
 	if (ordered) {
 		unlock_extent_cached(io_tree, page_start, page_end,
-				     &cached_state, GFP_NOFS);
+				     &cached_state);
 		unlock_page(page);
 		btrfs_start_ordered_extent(inode, ordered, 1);
 		btrfs_put_ordered_extent(ordered);
@@ -9170,13 +9041,13 @@ again:
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end,
 			  EXTENT_DIRTY | EXTENT_DELALLOC |
 			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
-			  0, 0, &cached_state, GFP_NOFS);
+			  0, 0, &cached_state);
 
 	ret = btrfs_set_extent_delalloc(inode, page_start, end, 0,
 					&cached_state, 0);
 	if (ret) {
 		unlock_extent_cached(io_tree, page_start, page_end,
-				     &cached_state, GFP_NOFS);
+				     &cached_state);
 		ret = VM_FAULT_SIGBUS;
 		goto out_unlock;
 	}
@@ -9202,7 +9073,7 @@ again:
 	BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
 	BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit;
 
-	unlock_extent_cached(io_tree, page_start, page_end, &cached_state, GFP_NOFS);
+	unlock_extent_cached(io_tree, page_start, page_end, &cached_state);
 
 out_unlock:
 	if (!ret) {
@@ -9427,7 +9298,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 	struct btrfs_inode *ei;
 	struct inode *inode;
 
-	ei = kmem_cache_alloc(btrfs_inode_cachep, GFP_NOFS);
+	ei = kmem_cache_alloc(btrfs_inode_cachep, GFP_KERNEL);
 	if (!ei)
 		return NULL;
 
@@ -9579,7 +9450,7 @@ void btrfs_destroy_cachep(void)
 	kmem_cache_destroy(btrfs_free_space_cachep);
 }
 
-int btrfs_init_cachep(void)
+int __init btrfs_init_cachep(void)
 {
 	btrfs_inode_cachep = kmem_cache_create("btrfs_inode",
 			sizeof(struct btrfs_inode), 0,
@@ -10694,7 +10565,6 @@ out:
 	btrfs_end_transaction(trans);
 	if (ret)
 		iput(inode);
-	btrfs_balance_delayed_items(fs_info);
 	btrfs_btree_balance_dirty(fs_info);
 	return ret;
 
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index aa452c9e2eff..111ee282b777 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -308,12 +308,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 		ip->flags |= BTRFS_INODE_COMPRESS;
 		ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
 
-		if (fs_info->compress_type == BTRFS_COMPRESS_LZO)
-			comp = "lzo";
-		else if (fs_info->compress_type == BTRFS_COMPRESS_ZLIB)
-			comp = "zlib";
-		else
-			comp = "zstd";
+		comp = btrfs_compress_type2str(fs_info->compress_type);
+		if (!comp || comp[0] == 0)
+			comp = btrfs_compress_type2str(BTRFS_COMPRESS_ZLIB);
+
 		ret = btrfs_set_prop(inode, "btrfs.compression",
 				     comp, strlen(comp), 0);
 		if (ret)
@@ -980,7 +978,7 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start)
 		/* get the big lock and read metadata off disk */
 		lock_extent_bits(io_tree, start, end, &cached);
 		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len, 0);
-		unlock_extent_cached(io_tree, start, end, &cached, GFP_NOFS);
+		unlock_extent_cached(io_tree, start, end, &cached);
 
 		if (IS_ERR(em))
 			return NULL;
@@ -1131,7 +1129,7 @@ again:
 			ordered = btrfs_lookup_ordered_extent(inode,
 							      page_start);
 			unlock_extent_cached(tree, page_start, page_end,
-					     &cached_state, GFP_NOFS);
+					     &cached_state);
 			if (!ordered)
 				break;
 
@@ -1191,7 +1189,7 @@ again:
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start,
 			  page_end - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
 			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0,
-			  &cached_state, GFP_NOFS);
+			  &cached_state);
 
 	if (i_done != page_cnt) {
 		spin_lock(&BTRFS_I(inode)->lock);
@@ -1207,8 +1205,7 @@ again:
 			  &cached_state);
 
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree,
-			     page_start, page_end - 1, &cached_state,
-			     GFP_NOFS);
+			     page_start, page_end - 1, &cached_state);
 
 	for (i = 0; i < i_done; i++) {
 		clear_page_dirty_for_io(pages[i]);
@@ -1504,7 +1501,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
 		goto out_free;
 	}
 
-	if (!device->writeable) {
+	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 		btrfs_info(fs_info,
 			   "resizer unable to apply on readonly device %llu",
 		       devid);
@@ -1529,7 +1526,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
 		}
 	}
 
-	if (device->is_tgtdev_for_dev_replace) {
+	if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
 		ret = -EPERM;
 		goto out_free;
 	}
@@ -2676,14 +2673,12 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
 		goto out;
 	}
 
-	mutex_lock(&fs_info->volume_mutex);
 	if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) {
 		ret = btrfs_rm_device(fs_info, NULL, vol_args->devid);
 	} else {
 		vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
 		ret = btrfs_rm_device(fs_info, vol_args->name, 0);
 	}
-	mutex_unlock(&fs_info->volume_mutex);
 	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 
 	if (!ret) {
@@ -2727,9 +2722,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
 	}
 
 	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
-	mutex_lock(&fs_info->volume_mutex);
 	ret = btrfs_rm_device(fs_info, vol_args->name, 0);
-	mutex_unlock(&fs_info->volume_mutex);
 
 	if (!ret)
 		btrfs_info(fs_info, "disk deleted %s", vol_args->name);
@@ -2754,16 +2747,16 @@ static long btrfs_ioctl_fs_info(struct btrfs_fs_info *fs_info,
 	if (!fi_args)
 		return -ENOMEM;
 
-	mutex_lock(&fs_devices->device_list_mutex);
+	rcu_read_lock();
 	fi_args->num_devices = fs_devices->num_devices;
-	memcpy(&fi_args->fsid, fs_info->fsid, sizeof(fi_args->fsid));
 
-	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+	list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
 		if (device->devid > fi_args->max_id)
 			fi_args->max_id = device->devid;
 	}
-	mutex_unlock(&fs_devices->device_list_mutex);
+	rcu_read_unlock();
 
+	memcpy(&fi_args->fsid, fs_info->fsid, sizeof(fi_args->fsid));
 	fi_args->nodesize = fs_info->nodesize;
 	fi_args->sectorsize = fs_info->sectorsize;
 	fi_args->clone_alignment = fs_info->sectorsize;
@@ -2780,7 +2773,6 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_ioctl_dev_info_args *di_args;
 	struct btrfs_device *dev;
-	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	int ret = 0;
 	char *s_uuid = NULL;
 
@@ -2791,7 +2783,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
 	if (!btrfs_is_empty_uuid(di_args->uuid))
 		s_uuid = di_args->uuid;
 
-	mutex_lock(&fs_devices->device_list_mutex);
+	rcu_read_lock();
 	dev = btrfs_find_device(fs_info, di_args->devid, s_uuid, NULL);
 
 	if (!dev) {
@@ -2806,17 +2798,15 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
 	if (dev->name) {
 		struct rcu_string *name;
 
-		rcu_read_lock();
 		name = rcu_dereference(dev->name);
-		strncpy(di_args->path, name->str, sizeof(di_args->path));
-		rcu_read_unlock();
+		strncpy(di_args->path, name->str, sizeof(di_args->path) - 1);
 		di_args->path[sizeof(di_args->path) - 1] = 0;
 	} else {
 		di_args->path[0] = '\0';
 	}
 
 out:
-	mutex_unlock(&fs_devices->device_list_mutex);
+	rcu_read_unlock();
 	if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))
 		ret = -EFAULT;
 
diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index f6a05f836629..b30a056963ab 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -164,7 +164,6 @@ static int iterate_object_props(struct btrfs_root *root,
 						 size_t),
 				void *ctx)
 {
-	struct btrfs_fs_info *fs_info = root->fs_info;
 	int ret;
 	char *name_buf = NULL;
 	char *value_buf = NULL;
@@ -215,12 +214,6 @@ static int iterate_object_props(struct btrfs_root *root,
 			name_ptr = (unsigned long)(di + 1);
 			data_ptr = name_ptr + name_len;
 
-			if (verify_dir_item(fs_info, leaf,
-					    path->slots[0], di)) {
-				ret = -EIO;
-				goto out;
-			}
-
 			if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
 			    memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
 						 name_ptr,
@@ -430,11 +423,11 @@ static const char *prop_compression_extract(struct inode *inode)
 {
 	switch (BTRFS_I(inode)->prop_compress) {
 	case BTRFS_COMPRESS_ZLIB:
-		return "zlib";
 	case BTRFS_COMPRESS_LZO:
-		return "lzo";
 	case BTRFS_COMPRESS_ZSTD:
-		return "zstd";
+		return btrfs_compress_type2str(BTRFS_I(inode)->prop_compress);
+	default:
+		break;
 	}
 
 	return NULL;
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 168fd03ca3ac..9e61dd624f7b 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2883,8 +2883,7 @@ cleanup:
 	ULIST_ITER_INIT(&uiter);
 	while ((unode = ulist_next(&reserved->range_changed, &uiter)))
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, unode->val,
-				 unode->aux, EXTENT_QGROUP_RESERVED, 0, 0, NULL,
-				 GFP_NOFS);
+				 unode->aux, EXTENT_QGROUP_RESERVED, 0, 0, NULL);
 	extent_changeset_release(reserved);
 	return ret;
 }
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index a7f79254ecca..dec0907dfb8a 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -231,7 +231,6 @@ int btrfs_alloc_stripe_hash_table(struct btrfs_fs_info *info)
 		cur = h + i;
 		INIT_LIST_HEAD(&cur->hash_list);
 		spin_lock_init(&cur->lock);
-		init_waitqueue_head(&cur->wait);
 	}
 
 	x = cmpxchg(&info->stripe_hash_table, NULL, table);
@@ -595,14 +594,31 @@ static int rbio_can_merge(struct btrfs_raid_bio *last,
 	 * bio list here, anyone else that wants to
 	 * change this stripe needs to do their own rmw.
 	 */
-	if (last->operation == BTRFS_RBIO_PARITY_SCRUB ||
-	    cur->operation == BTRFS_RBIO_PARITY_SCRUB)
+	if (last->operation == BTRFS_RBIO_PARITY_SCRUB)
 		return 0;
 
-	if (last->operation == BTRFS_RBIO_REBUILD_MISSING ||
-	    cur->operation == BTRFS_RBIO_REBUILD_MISSING)
+	if (last->operation == BTRFS_RBIO_REBUILD_MISSING)
 		return 0;
 
+	if (last->operation == BTRFS_RBIO_READ_REBUILD) {
+		int fa = last->faila;
+		int fb = last->failb;
+		int cur_fa = cur->faila;
+		int cur_fb = cur->failb;
+
+		if (last->faila >= last->failb) {
+			fa = last->failb;
+			fb = last->faila;
+		}
+
+		if (cur->faila >= cur->failb) {
+			cur_fa = cur->failb;
+			cur_fb = cur->faila;
+		}
+
+		if (fa != cur_fa || fb != cur_fb)
+			return 0;
+	}
 	return 1;
 }
 
@@ -670,7 +686,6 @@ static noinline int lock_stripe_add(struct btrfs_raid_bio *rbio)
 	struct btrfs_raid_bio *cur;
 	struct btrfs_raid_bio *pending;
 	unsigned long flags;
-	DEFINE_WAIT(wait);
 	struct btrfs_raid_bio *freeit = NULL;
 	struct btrfs_raid_bio *cache_drop = NULL;
 	int ret = 0;
@@ -816,15 +831,6 @@ static noinline void unlock_stripe(struct btrfs_raid_bio *rbio)
 			}
 
 			goto done_nolock;
-			/*
-			 * The barrier for this waitqueue_active is not needed,
-			 * we're protected by h->lock and can't miss a wakeup.
-			 */
-		} else if (waitqueue_active(&h->wait)) {
-			spin_unlock(&rbio->bio_list_lock);
-			spin_unlock_irqrestore(&h->lock, flags);
-			wake_up(&h->wait);
-			goto done_nolock;
 		}
 	}
 done:
@@ -858,10 +864,17 @@ static void __free_raid_bio(struct btrfs_raid_bio *rbio)
 	kfree(rbio);
 }
 
-static void free_raid_bio(struct btrfs_raid_bio *rbio)
+static void rbio_endio_bio_list(struct bio *cur, blk_status_t err)
 {
-	unlock_stripe(rbio);
-	__free_raid_bio(rbio);
+	struct bio *next;
+
+	while (cur) {
+		next = cur->bi_next;
+		cur->bi_next = NULL;
+		cur->bi_status = err;
+		bio_endio(cur);
+		cur = next;
+	}
 }
 
 /*
@@ -871,20 +884,26 @@ static void free_raid_bio(struct btrfs_raid_bio *rbio)
 static void rbio_orig_end_io(struct btrfs_raid_bio *rbio, blk_status_t err)
 {
 	struct bio *cur = bio_list_get(&rbio->bio_list);
-	struct bio *next;
+	struct bio *extra;
 
 	if (rbio->generic_bio_cnt)
 		btrfs_bio_counter_sub(rbio->fs_info, rbio->generic_bio_cnt);
 
-	free_raid_bio(rbio);
+	/*
+	 * At this moment, rbio->bio_list is empty, however since rbio does not
+	 * always have RBIO_RMW_LOCKED_BIT set and rbio is still linked on the
+	 * hash list, rbio may be merged with others so that rbio->bio_list
+	 * becomes non-empty.
+	 * Once unlock_stripe() is done, rbio->bio_list will not be updated any
+	 * more and we can call bio_endio() on all queued bios.
+	 */
+	unlock_stripe(rbio);
+	extra = bio_list_get(&rbio->bio_list);
+	__free_raid_bio(rbio);
 
-	while (cur) {
-		next = cur->bi_next;
-		cur->bi_next = NULL;
-		cur->bi_status = err;
-		bio_endio(cur);
-		cur = next;
-	}
+	rbio_endio_bio_list(cur, err);
+	if (extra)
+		rbio_endio_bio_list(extra, err);
 }
 
 /*
@@ -1435,14 +1454,13 @@ static int fail_bio_stripe(struct btrfs_raid_bio *rbio,
  */
 static void set_bio_pages_uptodate(struct bio *bio)
 {
-	struct bio_vec bvec;
-	struct bvec_iter iter;
+	struct bio_vec *bvec;
+	int i;
 
-	if (bio_flagged(bio, BIO_CLONED))
-		bio->bi_iter = btrfs_io_bio(bio)->iter;
+	ASSERT(!bio_flagged(bio, BIO_CLONED));
 
-	bio_for_each_segment(bvec, bio, iter)
-		SetPageUptodate(bvec.bv_page);
+	bio_for_each_segment_all(bvec, bio, i)
+		SetPageUptodate(bvec->bv_page);
 }
 
 /*
@@ -1969,7 +1987,22 @@ cleanup:
 
 cleanup_io:
 	if (rbio->operation == BTRFS_RBIO_READ_REBUILD) {
-		if (err == BLK_STS_OK)
+		/*
+		 * - In case of two failures, where rbio->failb != -1:
+		 *
+		 *   Do not cache this rbio since the above read reconstruction
+		 *   (raid6_datap_recov() or raid6_2data_recov()) may have
+		 *   changed some content of stripes which are not identical to
+		 *   on-disk content any more, otherwise, a later write/recover
+		 *   may steal stripe_pages from this rbio and end up with
+		 *   corruptions or rebuild failures.
+		 *
+		 * - In case of single failure, where rbio->failb == -1:
+		 *
+		 *   Cache this rbio iff the above read reconstruction is
+		 *   excuted without problems.
+		 */
+		if (err == BLK_STS_OK && rbio->failb < 0)
 			cache_rbio_pages(rbio);
 		else
 			clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
@@ -2170,11 +2203,21 @@ int raid56_parity_recover(struct btrfs_fs_info *fs_info, struct bio *bio,
 	}
 
 	/*
-	 * reconstruct from the q stripe if they are
-	 * asking for mirror 3
+	 * Loop retry:
+	 * for 'mirror == 2', reconstruct from all other stripes.
+	 * for 'mirror_num > 2', select a stripe to fail on every retry.
 	 */
-	if (mirror_num == 3)
-		rbio->failb = rbio->real_stripes - 2;
+	if (mirror_num > 2) {
+		/*
+		 * 'mirror == 3' is to fail the p stripe and
+		 * reconstruct from the q stripe.  'mirror > 3' is to
+		 * fail a data stripe and reconstruct from p+q stripe.
+		 */
+		rbio->failb = rbio->real_stripes - (mirror_num - 1);
+		ASSERT(rbio->failb > 0);
+		if (rbio->failb <= rbio->faila)
+			rbio->failb--;
+	}
 
 	ret = lock_stripe_add(rbio);
 
diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index 34878699d363..171f3cce30e6 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -606,8 +606,7 @@ static int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path,
 }
 
 /* Walk up to the next node that needs to be processed */
-static int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path,
-			int *level)
+static int walk_up_tree(struct btrfs_path *path, int *level)
 {
 	int l;
 
@@ -984,7 +983,6 @@ void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, u64 start,
 int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_path *path;
-	struct btrfs_root *root;
 	struct extent_buffer *eb;
 	u64 bytenr = 0, num_bytes = 0;
 	int ret, level;
@@ -1014,7 +1012,7 @@ int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
 				     &bytenr, &num_bytes);
 		if (ret)
 			break;
-		ret = walk_up_tree(root, path, &level);
+		ret = walk_up_tree(path, &level);
 		if (ret < 0)
 			break;
 		if (ret > 0) {
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 3338407ef0f0..aab0194efe46 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -387,13 +387,6 @@ again:
 		WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 		WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 		ptr = (unsigned long)(ref + 1);
-		ret = btrfs_is_name_len_valid(leaf, path->slots[0], ptr,
-					      name_len);
-		if (!ret) {
-			err = -EIO;
-			goto out;
-		}
-
 		WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 		*sequence = btrfs_root_ref_sequence(leaf, ref);
 
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index b2f871d80982..ec56f33feea9 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -301,6 +301,11 @@ static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 static void scrub_put_ctx(struct scrub_ctx *sctx);
 
+static inline int scrub_is_page_on_raid56(struct scrub_page *page)
+{
+	return page->recover &&
+	       (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
+}
 
 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 {
@@ -1323,15 +1328,34 @@ nodatasum_case:
 	 * could happen otherwise that a correct page would be
 	 * overwritten by a bad one).
 	 */
-	for (mirror_index = 0;
-	     mirror_index < BTRFS_MAX_MIRRORS &&
-	     sblocks_for_recheck[mirror_index].page_count > 0;
-	     mirror_index++) {
+	for (mirror_index = 0; ;mirror_index++) {
 		struct scrub_block *sblock_other;
 
 		if (mirror_index == failed_mirror_index)
 			continue;
-		sblock_other = sblocks_for_recheck + mirror_index;
+
+		/* raid56's mirror can be more than BTRFS_MAX_MIRRORS */
+		if (!scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
+			if (mirror_index >= BTRFS_MAX_MIRRORS)
+				break;
+			if (!sblocks_for_recheck[mirror_index].page_count)
+				break;
+
+			sblock_other = sblocks_for_recheck + mirror_index;
+		} else {
+			struct scrub_recover *r = sblock_bad->pagev[0]->recover;
+			int max_allowed = r->bbio->num_stripes -
+						r->bbio->num_tgtdevs;
+
+			if (mirror_index >= max_allowed)
+				break;
+			if (!sblocks_for_recheck[1].page_count)
+				break;
+
+			ASSERT(failed_mirror_index == 0);
+			sblock_other = sblocks_for_recheck + 1;
+			sblock_other->pagev[0]->mirror_num = 1 + mirror_index;
+		}
 
 		/* build and submit the bios, check checksums */
 		scrub_recheck_block(fs_info, sblock_other, 0);
@@ -1666,49 +1690,32 @@ leave_nomem:
 	return 0;
 }
 
-struct scrub_bio_ret {
-	struct completion event;
-	blk_status_t status;
-};
-
 static void scrub_bio_wait_endio(struct bio *bio)
 {
-	struct scrub_bio_ret *ret = bio->bi_private;
-
-	ret->status = bio->bi_status;
-	complete(&ret->event);
-}
-
-static inline int scrub_is_page_on_raid56(struct scrub_page *page)
-{
-	return page->recover &&
-	       (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
+	complete(bio->bi_private);
 }
 
 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
 					struct bio *bio,
 					struct scrub_page *page)
 {
-	struct scrub_bio_ret done;
+	DECLARE_COMPLETION_ONSTACK(done);
 	int ret;
+	int mirror_num;
 
-	init_completion(&done.event);
-	done.status = 0;
 	bio->bi_iter.bi_sector = page->logical >> 9;
 	bio->bi_private = &done;
 	bio->bi_end_io = scrub_bio_wait_endio;
 
+	mirror_num = page->sblock->pagev[0]->mirror_num;
 	ret = raid56_parity_recover(fs_info, bio, page->recover->bbio,
 				    page->recover->map_length,
-				    page->mirror_num, 0);
+				    mirror_num, 0);
 	if (ret)
 		return ret;
 
-	wait_for_completion_io(&done.event);
-	if (done.status)
-		return -EIO;
-
-	return 0;
+	wait_for_completion_io(&done);
+	return blk_status_to_errno(bio->bi_status);
 }
 
 /*
@@ -2535,7 +2542,7 @@ leave_nomem:
 	}
 
 	WARN_ON(sblock->page_count == 0);
-	if (dev->missing) {
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
 		/*
 		 * This case should only be hit for RAID 5/6 device replace. See
 		 * the comment in scrub_missing_raid56_pages() for details.
@@ -2870,7 +2877,7 @@ static int scrub_extent_for_parity(struct scrub_parity *sparity,
 	u8 csum[BTRFS_CSUM_SIZE];
 	u32 blocksize;
 
-	if (dev->missing) {
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
 		scrub_parity_mark_sectors_error(sparity, logical, len);
 		return 0;
 	}
@@ -4112,12 +4119,14 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
 	dev = btrfs_find_device(fs_info, devid, NULL, NULL);
-	if (!dev || (dev->missing && !is_dev_replace)) {
+	if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) &&
+		     !is_dev_replace)) {
 		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 		return -ENODEV;
 	}
 
-	if (!is_dev_replace && !readonly && !dev->writeable) {
+	if (!is_dev_replace && !readonly &&
+	    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
 		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 		rcu_read_lock();
 		name = rcu_dereference(dev->name);
@@ -4128,14 +4137,15 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 	}
 
 	mutex_lock(&fs_info->scrub_lock);
-	if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
+	if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
+	    test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) {
 		mutex_unlock(&fs_info->scrub_lock);
 		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 		return -EIO;
 	}
 
 	btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
-	if (dev->scrub_device ||
+	if (dev->scrub_ctx ||
 	    (!is_dev_replace &&
 	     btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
 		btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
@@ -4160,7 +4170,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 		return PTR_ERR(sctx);
 	}
 	sctx->readonly = readonly;
-	dev->scrub_device = sctx;
+	dev->scrub_ctx = sctx;
 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 
 	/*
@@ -4195,7 +4205,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 		memcpy(progress, &sctx->stat, sizeof(*progress));
 
 	mutex_lock(&fs_info->scrub_lock);
-	dev->scrub_device = NULL;
+	dev->scrub_ctx = NULL;
 	scrub_workers_put(fs_info);
 	mutex_unlock(&fs_info->scrub_lock);
 
@@ -4252,16 +4262,16 @@ int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
 	struct scrub_ctx *sctx;
 
 	mutex_lock(&fs_info->scrub_lock);
-	sctx = dev->scrub_device;
+	sctx = dev->scrub_ctx;
 	if (!sctx) {
 		mutex_unlock(&fs_info->scrub_lock);
 		return -ENOTCONN;
 	}
 	atomic_inc(&sctx->cancel_req);
-	while (dev->scrub_device) {
+	while (dev->scrub_ctx) {
 		mutex_unlock(&fs_info->scrub_lock);
 		wait_event(fs_info->scrub_pause_wait,
-			   dev->scrub_device == NULL);
+			   dev->scrub_ctx == NULL);
 		mutex_lock(&fs_info->scrub_lock);
 	}
 	mutex_unlock(&fs_info->scrub_lock);
@@ -4278,7 +4288,7 @@ int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
 	dev = btrfs_find_device(fs_info, devid, NULL, NULL);
 	if (dev)
-		sctx = dev->scrub_device;
+		sctx = dev->scrub_ctx;
 	if (sctx)
 		memcpy(progress, &sctx->stat, sizeof(*progress));
 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
@@ -4478,8 +4488,7 @@ static int check_extent_to_block(struct btrfs_inode *inode, u64 start, u64 len,
 	free_extent_map(em);
 
 out_unlock:
-	unlock_extent_cached(io_tree, lockstart, lockend, &cached_state,
-			     GFP_NOFS);
+	unlock_extent_cached(io_tree, lockstart, lockend, &cached_state);
 	return ret;
 }
 
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 20d3300bd268..f306c608dc28 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1059,12 +1059,6 @@ static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
 			}
 		}
 
-		ret = btrfs_is_name_len_valid(eb, path->slots[0],
-			  (unsigned long)(di + 1), name_len + data_len);
-		if (!ret) {
-			ret = -EIO;
-			goto out;
-		}
 		if (name_len + data_len > buf_len) {
 			buf_len = name_len + data_len;
 			if (is_vmalloc_addr(buf)) {
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3a4dce153645..6e71a2a78363 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -61,12 +61,21 @@
 #include "tests/btrfs-tests.h"
 
 #include "qgroup.h"
-#include "backref.h"
 #define CREATE_TRACE_POINTS
 #include <trace/events/btrfs.h>
 
 static const struct super_operations btrfs_super_ops;
+
+/*
+ * Types for mounting the default subvolume and a subvolume explicitly
+ * requested by subvol=/path. That way the callchain is straightforward and we
+ * don't have to play tricks with the mount options and recursive calls to
+ * btrfs_mount.
+ *
+ * The new btrfs_root_fs_type also servers as a tag for the bdev_holder.
+ */
 static struct file_system_type btrfs_fs_type;
+static struct file_system_type btrfs_root_fs_type;
 
 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
 
@@ -98,30 +107,6 @@ const char *btrfs_decode_error(int errno)
 	return errstr;
 }
 
-/* btrfs handle error by forcing the filesystem readonly */
-static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
-{
-	struct super_block *sb = fs_info->sb;
-
-	if (sb_rdonly(sb))
-		return;
-
-	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
-		sb->s_flags |= SB_RDONLY;
-		btrfs_info(fs_info, "forced readonly");
-		/*
-		 * Note that a running device replace operation is not
-		 * canceled here although there is no way to update
-		 * the progress. It would add the risk of a deadlock,
-		 * therefore the canceling is omitted. The only penalty
-		 * is that some I/O remains active until the procedure
-		 * completes. The next time when the filesystem is
-		 * mounted writeable again, the device replace
-		 * operation continues.
-		 */
-	}
-}
-
 /*
  * __btrfs_handle_fs_error decodes expected errors from the caller and
  * invokes the approciate error response.
@@ -168,8 +153,23 @@ void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function
 	set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 
 	/* Don't go through full error handling during mount */
-	if (sb->s_flags & SB_BORN)
-		btrfs_handle_error(fs_info);
+	if (!(sb->s_flags & SB_BORN))
+		return;
+
+	if (sb_rdonly(sb))
+		return;
+
+	/* btrfs handle error by forcing the filesystem readonly */
+	sb->s_flags |= SB_RDONLY;
+	btrfs_info(fs_info, "forced readonly");
+	/*
+	 * Note that a running device replace operation is not canceled here
+	 * although there is no way to update the progress. It would add the
+	 * risk of a deadlock, therefore the canceling is omitted. The only
+	 * penalty is that some I/O remains active until the procedure
+	 * completes. The next time when the filesystem is mounted writeable
+	 * again, the device replace operation continues.
+	 */
 }
 
 #ifdef CONFIG_PRINTK
@@ -405,7 +405,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 			unsigned long new_flags)
 {
 	substring_t args[MAX_OPT_ARGS];
-	char *p, *num, *orig = NULL;
+	char *p, *num;
 	u64 cache_gen;
 	int intarg;
 	int ret = 0;
@@ -428,16 +428,6 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 	if (!options)
 		goto check;
 
-	/*
-	 * strsep changes the string, duplicate it because parse_options
-	 * gets called twice
-	 */
-	options = kstrdup(options, GFP_KERNEL);
-	if (!options)
-		return -ENOMEM;
-
-	orig = options;
-
 	while ((p = strsep(&options, ",")) != NULL) {
 		int token;
 		if (!*p)
@@ -454,7 +444,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 		case Opt_subvolrootid:
 		case Opt_device:
 			/*
-			 * These are parsed by btrfs_parse_early_options
+			 * These are parsed by btrfs_parse_subvol_options
+			 * and btrfs_parse_early_options
 			 * and can be happily ignored here.
 			 */
 			break;
@@ -877,7 +868,6 @@ out:
 		btrfs_info(info, "disk space caching is enabled");
 	if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))
 		btrfs_info(info, "using free space tree");
-	kfree(orig);
 	return ret;
 }
 
@@ -888,11 +878,60 @@ out:
  * only when we need to allocate a new super block.
  */
 static int btrfs_parse_early_options(const char *options, fmode_t flags,
-		void *holder, char **subvol_name, u64 *subvol_objectid,
-		struct btrfs_fs_devices **fs_devices)
+		void *holder, struct btrfs_fs_devices **fs_devices)
 {
 	substring_t args[MAX_OPT_ARGS];
 	char *device_name, *opts, *orig, *p;
+	int error = 0;
+
+	if (!options)
+		return 0;
+
+	/*
+	 * strsep changes the string, duplicate it because btrfs_parse_options
+	 * gets called later
+	 */
+	opts = kstrdup(options, GFP_KERNEL);
+	if (!opts)
+		return -ENOMEM;
+	orig = opts;
+
+	while ((p = strsep(&opts, ",")) != NULL) {
+		int token;
+
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		if (token == Opt_device) {
+			device_name = match_strdup(&args[0]);
+			if (!device_name) {
+				error = -ENOMEM;
+				goto out;
+			}
+			error = btrfs_scan_one_device(device_name,
+					flags, holder, fs_devices);
+			kfree(device_name);
+			if (error)
+				goto out;
+		}
+	}
+
+out:
+	kfree(orig);
+	return error;
+}
+
+/*
+ * Parse mount options that are related to subvolume id
+ *
+ * The value is later passed to mount_subvol()
+ */
+static int btrfs_parse_subvol_options(const char *options, fmode_t flags,
+		char **subvol_name, u64 *subvol_objectid)
+{
+	substring_t args[MAX_OPT_ARGS];
+	char *opts, *orig, *p;
 	char *num = NULL;
 	int error = 0;
 
@@ -900,8 +939,8 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
 		return 0;
 
 	/*
-	 * strsep changes the string, duplicate it because parse_options
-	 * gets called twice
+	 * strsep changes the string, duplicate it because
+	 * btrfs_parse_early_options gets called later
 	 */
 	opts = kstrdup(options, GFP_KERNEL);
 	if (!opts)
@@ -940,18 +979,6 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
 		case Opt_subvolrootid:
 			pr_warn("BTRFS: 'subvolrootid' mount option is deprecated and has no effect\n");
 			break;
-		case Opt_device:
-			device_name = match_strdup(&args[0]);
-			if (!device_name) {
-				error = -ENOMEM;
-				goto out;
-			}
-			error = btrfs_scan_one_device(device_name,
-					flags, holder, fs_devices);
-			kfree(device_name);
-			if (error)
-				goto out;
-			break;
 		default:
 			break;
 		}
@@ -1243,7 +1270,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 {
 	struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
-	char *compress_type;
+	const char *compress_type;
 
 	if (btrfs_test_opt(info, DEGRADED))
 		seq_puts(seq, ",degraded");
@@ -1259,12 +1286,7 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 					     num_online_cpus() + 2, 8))
 		seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 	if (btrfs_test_opt(info, COMPRESS)) {
-		if (info->compress_type == BTRFS_COMPRESS_ZLIB)
-			compress_type = "zlib";
-		else if (info->compress_type == BTRFS_COMPRESS_LZO)
-			compress_type = "lzo";
-		else
-			compress_type = "zstd";
+		compress_type = btrfs_compress_type2str(info->compress_type);
 		if (btrfs_test_opt(info, FORCE_COMPRESS))
 			seq_printf(seq, ",compress-force=%s", compress_type);
 		else
@@ -1365,86 +1387,12 @@ static inline int is_subvolume_inode(struct inode *inode)
 	return 0;
 }
 
-/*
- * This will add subvolid=0 to the argument string while removing any subvol=
- * and subvolid= arguments to make sure we get the top-level root for path
- * walking to the subvol we want.
- */
-static char *setup_root_args(char *args)
-{
-	char *buf, *dst, *sep;
-
-	if (!args)
-		return kstrdup("subvolid=0", GFP_KERNEL);
-
-	/* The worst case is that we add ",subvolid=0" to the end. */
-	buf = dst = kmalloc(strlen(args) + strlen(",subvolid=0") + 1,
-			GFP_KERNEL);
-	if (!buf)
-		return NULL;
-
-	while (1) {
-		sep = strchrnul(args, ',');
-		if (!strstarts(args, "subvol=") &&
-		    !strstarts(args, "subvolid=")) {
-			memcpy(dst, args, sep - args);
-			dst += sep - args;
-			*dst++ = ',';
-		}
-		if (*sep)
-			args = sep + 1;
-		else
-			break;
-	}
-	strcpy(dst, "subvolid=0");
-
-	return buf;
-}
-
 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
-				   int flags, const char *device_name,
-				   char *data)
+				   const char *device_name, struct vfsmount *mnt)
 {
 	struct dentry *root;
-	struct vfsmount *mnt = NULL;
-	char *newargs;
 	int ret;
 
-	newargs = setup_root_args(data);
-	if (!newargs) {
-		root = ERR_PTR(-ENOMEM);
-		goto out;
-	}
-
-	mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name, newargs);
-	if (PTR_ERR_OR_ZERO(mnt) == -EBUSY) {
-		if (flags & SB_RDONLY) {
-			mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~SB_RDONLY,
-					     device_name, newargs);
-		} else {
-			mnt = vfs_kern_mount(&btrfs_fs_type, flags | SB_RDONLY,
-					     device_name, newargs);
-			if (IS_ERR(mnt)) {
-				root = ERR_CAST(mnt);
-				mnt = NULL;
-				goto out;
-			}
-
-			down_write(&mnt->mnt_sb->s_umount);
-			ret = btrfs_remount(mnt->mnt_sb, &flags, NULL);
-			up_write(&mnt->mnt_sb->s_umount);
-			if (ret < 0) {
-				root = ERR_PTR(ret);
-				goto out;
-			}
-		}
-	}
-	if (IS_ERR(mnt)) {
-		root = ERR_CAST(mnt);
-		mnt = NULL;
-		goto out;
-	}
-
 	if (!subvol_name) {
 		if (!subvol_objectid) {
 			ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
@@ -1500,7 +1448,6 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
 
 out:
 	mntput(mnt);
-	kfree(newargs);
 	kfree(subvol_name);
 	return root;
 }
@@ -1558,11 +1505,11 @@ static int setup_security_options(struct btrfs_fs_info *fs_info,
 /*
  * Find a superblock for the given device / mount point.
  *
- * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
- *	  for multiple device setup.  Make sure to keep it in sync.
+ * Note: This is based on mount_bdev from fs/super.c with a few additions
+ *       for multiple device setup.  Make sure to keep it in sync.
  */
-static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
-		const char *device_name, void *data)
+static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
+		int flags, const char *device_name, void *data)
 {
 	struct block_device *bdev = NULL;
 	struct super_block *s;
@@ -1570,27 +1517,17 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 	struct btrfs_fs_info *fs_info = NULL;
 	struct security_mnt_opts new_sec_opts;
 	fmode_t mode = FMODE_READ;
-	char *subvol_name = NULL;
-	u64 subvol_objectid = 0;
 	int error = 0;
 
 	if (!(flags & SB_RDONLY))
 		mode |= FMODE_WRITE;
 
 	error = btrfs_parse_early_options(data, mode, fs_type,
-					  &subvol_name, &subvol_objectid,
 					  &fs_devices);
 	if (error) {
-		kfree(subvol_name);
 		return ERR_PTR(error);
 	}
 
-	if (subvol_name || subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
-		/* mount_subvol() will free subvol_name. */
-		return mount_subvol(subvol_name, subvol_objectid, flags,
-				    device_name, data);
-	}
-
 	security_init_mnt_opts(&new_sec_opts);
 	if (data) {
 		error = parse_security_options(data, &new_sec_opts);
@@ -1674,6 +1611,84 @@ error_sec_opts:
 	return ERR_PTR(error);
 }
 
+/*
+ * Mount function which is called by VFS layer.
+ *
+ * In order to allow mounting a subvolume directly, btrfs uses mount_subtree()
+ * which needs vfsmount* of device's root (/).  This means device's root has to
+ * be mounted internally in any case.
+ *
+ * Operation flow:
+ *   1. Parse subvol id related options for later use in mount_subvol().
+ *
+ *   2. Mount device's root (/) by calling vfs_kern_mount().
+ *
+ *      NOTE: vfs_kern_mount() is used by VFS to call btrfs_mount() in the
+ *      first place. In order to avoid calling btrfs_mount() again, we use
+ *      different file_system_type which is not registered to VFS by
+ *      register_filesystem() (btrfs_root_fs_type). As a result,
+ *      btrfs_mount_root() is called. The return value will be used by
+ *      mount_subtree() in mount_subvol().
+ *
+ *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
+ *      "btrfs subvolume set-default", mount_subvol() is called always.
+ */
+static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
+		const char *device_name, void *data)
+{
+	struct vfsmount *mnt_root;
+	struct dentry *root;
+	fmode_t mode = FMODE_READ;
+	char *subvol_name = NULL;
+	u64 subvol_objectid = 0;
+	int error = 0;
+
+	if (!(flags & SB_RDONLY))
+		mode |= FMODE_WRITE;
+
+	error = btrfs_parse_subvol_options(data, mode,
+					  &subvol_name, &subvol_objectid);
+	if (error) {
+		kfree(subvol_name);
+		return ERR_PTR(error);
+	}
+
+	/* mount device's root (/) */
+	mnt_root = vfs_kern_mount(&btrfs_root_fs_type, flags, device_name, data);
+	if (PTR_ERR_OR_ZERO(mnt_root) == -EBUSY) {
+		if (flags & SB_RDONLY) {
+			mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
+				flags & ~SB_RDONLY, device_name, data);
+		} else {
+			mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
+				flags | SB_RDONLY, device_name, data);
+			if (IS_ERR(mnt_root)) {
+				root = ERR_CAST(mnt_root);
+				goto out;
+			}
+
+			down_write(&mnt_root->mnt_sb->s_umount);
+			error = btrfs_remount(mnt_root->mnt_sb, &flags, NULL);
+			up_write(&mnt_root->mnt_sb->s_umount);
+			if (error < 0) {
+				root = ERR_PTR(error);
+				mntput(mnt_root);
+				goto out;
+			}
+		}
+	}
+	if (IS_ERR(mnt_root)) {
+		root = ERR_CAST(mnt_root);
+		goto out;
+	}
+
+	/* mount_subvol() will free subvol_name and mnt_root */
+	root = mount_subvol(subvol_name, subvol_objectid, device_name, mnt_root);
+
+out:
+	return root;
+}
+
 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
 				     int new_pool_size, int old_pool_size)
 {
@@ -1820,7 +1835,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 			goto restore;
 		}
 
-		if (!btrfs_check_rw_degradable(fs_info)) {
+		if (!btrfs_check_rw_degradable(fs_info, NULL)) {
 			btrfs_warn(fs_info,
 				"too many missing devices, writeable remount is not allowed");
 			ret = -EACCES;
@@ -1972,8 +1987,10 @@ static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
-		if (!device->in_fs_metadata || !device->bdev ||
-		    device->is_tgtdev_for_dev_replace)
+		if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+						&device->dev_state) ||
+		    !device->bdev ||
+		    test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
 			continue;
 
 		if (i >= nr_devices)
@@ -2174,6 +2191,15 @@ static struct file_system_type btrfs_fs_type = {
 	.kill_sb	= btrfs_kill_super,
 	.fs_flags	= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
 };
+
+static struct file_system_type btrfs_root_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "btrfs",
+	.mount		= btrfs_mount_root,
+	.kill_sb	= btrfs_kill_super,
+	.fs_flags	= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
+};
+
 MODULE_ALIAS_FS("btrfs");
 
 static int btrfs_control_open(struct inode *inode, struct file *file)
@@ -2207,11 +2233,11 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 	switch (cmd) {
 	case BTRFS_IOC_SCAN_DEV:
 		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
-					    &btrfs_fs_type, &fs_devices);
+					    &btrfs_root_fs_type, &fs_devices);
 		break;
 	case BTRFS_IOC_DEVICES_READY:
 		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
-					    &btrfs_fs_type, &fs_devices);
+					    &btrfs_root_fs_type, &fs_devices);
 		if (ret)
 			break;
 		ret = !(fs_devices->num_devices == fs_devices->total_devices);
@@ -2269,7 +2295,7 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
 	while (cur_devices) {
 		head = &cur_devices->devices;
 		list_for_each_entry(dev, head, dev_list) {
-			if (dev->missing)
+			if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
 				continue;
 			if (!dev->name)
 				continue;
@@ -2324,7 +2350,7 @@ static struct miscdevice btrfs_misc = {
 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
 MODULE_ALIAS("devname:btrfs-control");
 
-static int btrfs_interface_init(void)
+static int __init btrfs_interface_init(void)
 {
 	return misc_register(&btrfs_misc);
 }
@@ -2334,7 +2360,7 @@ static void btrfs_interface_exit(void)
 	misc_deregister(&btrfs_misc);
 }
 
-static void btrfs_print_mod_info(void)
+static void __init btrfs_print_mod_info(void)
 {
 	pr_info("Btrfs loaded, crc32c=%s"
 #ifdef CONFIG_BTRFS_DEBUG
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index a28bba801264..a8bafed931f4 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -897,7 +897,7 @@ static int btrfs_init_debugfs(void)
 	return 0;
 }
 
-int btrfs_init_sysfs(void)
+int __init btrfs_init_sysfs(void)
 {
 	int ret;
 
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index d3f25376a0f8..9786d8cd0aa6 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -277,6 +277,9 @@ int btrfs_run_sanity_tests(void)
 				goto out;
 		}
 	}
+	ret = btrfs_test_extent_map();
+	if (ret)
+		goto out;
 out:
 	btrfs_destroy_test_fs();
 	return ret;
diff --git a/fs/btrfs/tests/btrfs-tests.h b/fs/btrfs/tests/btrfs-tests.h
index 266f1e3d1784..bc0615bac3cc 100644
--- a/fs/btrfs/tests/btrfs-tests.h
+++ b/fs/btrfs/tests/btrfs-tests.h
@@ -33,6 +33,7 @@ int btrfs_test_extent_io(u32 sectorsize, u32 nodesize);
 int btrfs_test_inodes(u32 sectorsize, u32 nodesize);
 int btrfs_test_qgroups(u32 sectorsize, u32 nodesize);
 int btrfs_test_free_space_tree(u32 sectorsize, u32 nodesize);
+int btrfs_test_extent_map(void);
 struct inode *btrfs_new_test_inode(void);
 struct btrfs_fs_info *btrfs_alloc_dummy_fs_info(u32 nodesize, u32 sectorsize);
 void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info);
diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c
new file mode 100644
index 000000000000..70c993f01670
--- /dev/null
+++ b/fs/btrfs/tests/extent-map-tests.c
@@ -0,0 +1,366 @@
+/*
+ * Copyright (C) 2017 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/types.h>
+#include "btrfs-tests.h"
+#include "../ctree.h"
+
+static void free_extent_map_tree(struct extent_map_tree *em_tree)
+{
+	struct extent_map *em;
+	struct rb_node *node;
+
+	while (!RB_EMPTY_ROOT(&em_tree->map)) {
+		node = rb_first(&em_tree->map);
+		em = rb_entry(node, struct extent_map, rb_node);
+		remove_extent_mapping(em_tree, em);
+
+#ifdef CONFIG_BTRFS_DEBUG
+		if (refcount_read(&em->refs) != 1) {
+			test_msg(
+"em leak: em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx) refs %d\n",
+				 em->start, em->len, em->block_start,
+				 em->block_len, refcount_read(&em->refs));
+
+			refcount_set(&em->refs, 1);
+		}
+#endif
+		free_extent_map(em);
+	}
+}
+
+/*
+ * Test scenario:
+ *
+ * Suppose that no extent map has been loaded into memory yet, there is a file
+ * extent [0, 16K), followed by another file extent [16K, 20K), two dio reads
+ * are entering btrfs_get_extent() concurrently, t1 is reading [8K, 16K), t2 is
+ * reading [0, 8K)
+ *
+ *     t1                            t2
+ *  btrfs_get_extent()              btrfs_get_extent()
+ *    -> lookup_extent_mapping()      ->lookup_extent_mapping()
+ *    -> add_extent_mapping(0, 16K)
+ *    -> return em
+ *                                    ->add_extent_mapping(0, 16K)
+ *                                    -> #handle -EEXIST
+ */
+static void test_case_1(struct extent_map_tree *em_tree)
+{
+	struct extent_map *em;
+	u64 start = 0;
+	u64 len = SZ_8K;
+	int ret;
+
+	em = alloc_extent_map();
+	if (!em)
+		/* Skip the test on error. */
+		return;
+
+	/* Add [0, 16K) */
+	em->start = 0;
+	em->len = SZ_16K;
+	em->block_start = 0;
+	em->block_len = SZ_16K;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	/* Add [16K, 20K) following [0, 16K)  */
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+
+	em->start = SZ_16K;
+	em->len = SZ_4K;
+	em->block_start = SZ_32K; /* avoid merging */
+	em->block_len = SZ_4K;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+
+	/* Add [0, 8K), should return [0, 16K) instead. */
+	em->start = start;
+	em->len = len;
+	em->block_start = start;
+	em->block_len = len;
+	ret = btrfs_add_extent_mapping(em_tree, &em, em->start, em->len);
+	if (ret)
+		test_msg("case1 [%llu %llu]: ret %d\n", start, start + len, ret);
+	if (em &&
+	    (em->start != 0 || extent_map_end(em) != SZ_16K ||
+	     em->block_start != 0 || em->block_len != SZ_16K))
+		test_msg(
+"case1 [%llu %llu]: ret %d return a wrong em (start %llu len %llu block_start %llu block_len %llu\n",
+			 start, start + len, ret, em->start, em->len,
+			 em->block_start, em->block_len);
+	free_extent_map(em);
+out:
+	/* free memory */
+	free_extent_map_tree(em_tree);
+}
+
+/*
+ * Test scenario:
+ *
+ * Reading the inline ending up with EEXIST, ie. read an inline
+ * extent and discard page cache and read it again.
+ */
+static void test_case_2(struct extent_map_tree *em_tree)
+{
+	struct extent_map *em;
+	int ret;
+
+	em = alloc_extent_map();
+	if (!em)
+		/* Skip the test on error. */
+		return;
+
+	/* Add [0, 1K) */
+	em->start = 0;
+	em->len = SZ_1K;
+	em->block_start = EXTENT_MAP_INLINE;
+	em->block_len = (u64)-1;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	/* Add [4K, 4K) following [0, 1K)  */
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+
+	em->start = SZ_4K;
+	em->len = SZ_4K;
+	em->block_start = SZ_4K;
+	em->block_len = SZ_4K;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+
+	/* Add [0, 1K) */
+	em->start = 0;
+	em->len = SZ_1K;
+	em->block_start = EXTENT_MAP_INLINE;
+	em->block_len = (u64)-1;
+	ret = btrfs_add_extent_mapping(em_tree, &em, em->start, em->len);
+	if (ret)
+		test_msg("case2 [0 1K]: ret %d\n", ret);
+	if (em &&
+	    (em->start != 0 || extent_map_end(em) != SZ_1K ||
+	     em->block_start != EXTENT_MAP_INLINE || em->block_len != (u64)-1))
+		test_msg(
+"case2 [0 1K]: ret %d return a wrong em (start %llu len %llu block_start %llu block_len %llu\n",
+			 ret, em->start, em->len, em->block_start,
+			 em->block_len);
+	free_extent_map(em);
+out:
+	/* free memory */
+	free_extent_map_tree(em_tree);
+}
+
+static void __test_case_3(struct extent_map_tree *em_tree, u64 start)
+{
+	struct extent_map *em;
+	u64 len = SZ_4K;
+	int ret;
+
+	em = alloc_extent_map();
+	if (!em)
+		/* Skip this test on error. */
+		return;
+
+	/* Add [4K, 8K) */
+	em->start = SZ_4K;
+	em->len = SZ_4K;
+	em->block_start = SZ_4K;
+	em->block_len = SZ_4K;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+
+	/* Add [0, 16K) */
+	em->start = 0;
+	em->len = SZ_16K;
+	em->block_start = 0;
+	em->block_len = SZ_16K;
+	ret = btrfs_add_extent_mapping(em_tree, &em, start, len);
+	if (ret)
+		test_msg("case3 [0x%llx 0x%llx): ret %d\n",
+			 start, start + len, ret);
+	/*
+	 * Since bytes within em are contiguous, em->block_start is identical to
+	 * em->start.
+	 */
+	if (em &&
+	    (start < em->start || start + len > extent_map_end(em) ||
+	     em->start != em->block_start || em->len != em->block_len))
+		test_msg(
+"case3 [0x%llx 0x%llx): ret %d em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx)\n",
+			 start, start + len, ret, em->start, em->len,
+			 em->block_start, em->block_len);
+	free_extent_map(em);
+out:
+	/* free memory */
+	free_extent_map_tree(em_tree);
+}
+
+/*
+ * Test scenario:
+ *
+ * Suppose that no extent map has been loaded into memory yet.
+ * There is a file extent [0, 16K), two jobs are running concurrently
+ * against it, t1 is buffered writing to [4K, 8K) and t2 is doing dio
+ * read from [0, 4K) or [8K, 12K) or [12K, 16K).
+ *
+ * t1 goes ahead of t2 and adds em [4K, 8K) into tree.
+ *
+ *         t1                       t2
+ *  cow_file_range()	     btrfs_get_extent()
+ *                            -> lookup_extent_mapping()
+ *   -> add_extent_mapping()
+ *                            -> add_extent_mapping()
+ */
+static void test_case_3(struct extent_map_tree *em_tree)
+{
+	__test_case_3(em_tree, 0);
+	__test_case_3(em_tree, SZ_8K);
+	__test_case_3(em_tree, (12 * 1024ULL));
+}
+
+static void __test_case_4(struct extent_map_tree *em_tree, u64 start)
+{
+	struct extent_map *em;
+	u64 len = SZ_4K;
+	int ret;
+
+	em = alloc_extent_map();
+	if (!em)
+		/* Skip this test on error. */
+		return;
+
+	/* Add [0K, 8K) */
+	em->start = 0;
+	em->len = SZ_8K;
+	em->block_start = 0;
+	em->block_len = SZ_8K;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+
+	/* Add [8K, 24K) */
+	em->start = SZ_8K;
+	em->len = 24 * 1024ULL;
+	em->block_start = SZ_16K; /* avoid merging */
+	em->block_len = 24 * 1024ULL;
+	ret = add_extent_mapping(em_tree, em, 0);
+	ASSERT(ret == 0);
+	free_extent_map(em);
+
+	em = alloc_extent_map();
+	if (!em)
+		goto out;
+	/* Add [0K, 32K) */
+	em->start = 0;
+	em->len = SZ_32K;
+	em->block_start = 0;
+	em->block_len = SZ_32K;
+	ret = btrfs_add_extent_mapping(em_tree, &em, start, len);
+	if (ret)
+		test_msg("case4 [0x%llx 0x%llx): ret %d\n",
+			 start, len, ret);
+	if (em &&
+	    (start < em->start || start + len > extent_map_end(em)))
+		test_msg(
+"case4 [0x%llx 0x%llx): ret %d, added wrong em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx)\n",
+			 start, len, ret, em->start, em->len, em->block_start,
+			 em->block_len);
+	free_extent_map(em);
+out:
+	/* free memory */
+	free_extent_map_tree(em_tree);
+}
+
+/*
+ * Test scenario:
+ *
+ * Suppose that no extent map has been loaded into memory yet.
+ * There is a file extent [0, 32K), two jobs are running concurrently
+ * against it, t1 is doing dio write to [8K, 32K) and t2 is doing dio
+ * read from [0, 4K) or [4K, 8K).
+ *
+ * t1 goes ahead of t2 and splits em [0, 32K) to em [0K, 8K) and [8K 32K).
+ *
+ *         t1                                t2
+ *  btrfs_get_blocks_direct()	       btrfs_get_blocks_direct()
+ *   -> btrfs_get_extent()              -> btrfs_get_extent()
+ *       -> lookup_extent_mapping()
+ *       -> add_extent_mapping()            -> lookup_extent_mapping()
+ *          # load [0, 32K)
+ *   -> btrfs_new_extent_direct()
+ *       -> btrfs_drop_extent_cache()
+ *          # split [0, 32K)
+ *       -> add_extent_mapping()
+ *          # add [8K, 32K)
+ *                                          -> add_extent_mapping()
+ *                                             # handle -EEXIST when adding
+ *                                             # [0, 32K)
+ */
+static void test_case_4(struct extent_map_tree *em_tree)
+{
+	__test_case_4(em_tree, 0);
+	__test_case_4(em_tree, SZ_4K);
+}
+
+int btrfs_test_extent_map()
+{
+	struct extent_map_tree *em_tree;
+
+	test_msg("Running extent_map tests\n");
+
+	em_tree = kzalloc(sizeof(*em_tree), GFP_KERNEL);
+	if (!em_tree)
+		/* Skip the test on error. */
+		return 0;
+
+	extent_map_tree_init(em_tree);
+
+	test_case_1(em_tree);
+	test_case_2(em_tree);
+	test_case_3(em_tree);
+	test_case_4(em_tree);
+
+	kfree(em_tree);
+	return 0;
+}
diff --git a/fs/btrfs/tests/inode-tests.c b/fs/btrfs/tests/inode-tests.c
index 30affb60da51..13420cd19ef0 100644
--- a/fs/btrfs/tests/inode-tests.c
+++ b/fs/btrfs/tests/inode-tests.c
@@ -288,10 +288,6 @@ static noinline int test_btrfs_get_extent(u32 sectorsize, u32 nodesize)
 		test_msg("Expected a hole, got %llu\n", em->block_start);
 		goto out;
 	}
-	if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
-		test_msg("Vacancy flag wasn't set properly\n");
-		goto out;
-	}
 	free_extent_map(em);
 	btrfs_drop_extent_cache(BTRFS_I(inode), 0, (u64)-1, 0);
 
@@ -1001,8 +997,7 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 			       BTRFS_MAX_EXTENT_SIZE >> 1,
 			       (BTRFS_MAX_EXTENT_SIZE >> 1) + sectorsize - 1,
 			       EXTENT_DELALLOC | EXTENT_DIRTY |
-			       EXTENT_UPTODATE, 0, 0,
-			       NULL, GFP_KERNEL);
+			       EXTENT_UPTODATE, 0, 0, NULL);
 	if (ret) {
 		test_msg("clear_extent_bit returned %d\n", ret);
 		goto out;
@@ -1070,8 +1065,7 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 			       BTRFS_MAX_EXTENT_SIZE + sectorsize,
 			       BTRFS_MAX_EXTENT_SIZE + 2 * sectorsize - 1,
 			       EXTENT_DIRTY | EXTENT_DELALLOC |
-			       EXTENT_UPTODATE, 0, 0,
-			       NULL, GFP_KERNEL);
+			       EXTENT_UPTODATE, 0, 0, NULL);
 	if (ret) {
 		test_msg("clear_extent_bit returned %d\n", ret);
 		goto out;
@@ -1104,8 +1098,7 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 	/* Empty */
 	ret = clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, (u64)-1,
 			       EXTENT_DIRTY | EXTENT_DELALLOC |
-			       EXTENT_UPTODATE, 0, 0,
-			       NULL, GFP_KERNEL);
+			       EXTENT_UPTODATE, 0, 0, NULL);
 	if (ret) {
 		test_msg("clear_extent_bit returned %d\n", ret);
 		goto out;
@@ -1121,8 +1114,7 @@ out:
 	if (ret)
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, (u64)-1,
 				 EXTENT_DIRTY | EXTENT_DELALLOC |
-				 EXTENT_UPTODATE, 0, 0,
-				 NULL, GFP_KERNEL);
+				 EXTENT_UPTODATE, 0, 0, NULL);
 	iput(inode);
 	btrfs_free_dummy_root(root);
 	btrfs_free_dummy_fs_info(fs_info);
@@ -1134,7 +1126,6 @@ int btrfs_test_inodes(u32 sectorsize, u32 nodesize)
 	int ret;
 
 	set_bit(EXTENT_FLAG_COMPRESSED, &compressed_only);
-	set_bit(EXTENT_FLAG_VACANCY, &vacancy_only);
 	set_bit(EXTENT_FLAG_PREALLOC, &prealloc_only);
 
 	test_msg("Running btrfs_get_extent tests\n");
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5a8c2649af2f..04f07144b45c 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -495,8 +495,8 @@ start_transaction(struct btrfs_root *root, unsigned int num_items,
 	if (current->journal_info) {
 		WARN_ON(type & TRANS_EXTWRITERS);
 		h = current->journal_info;
-		h->use_count++;
-		WARN_ON(h->use_count > 2);
+		refcount_inc(&h->use_count);
+		WARN_ON(refcount_read(&h->use_count) > 2);
 		h->orig_rsv = h->block_rsv;
 		h->block_rsv = NULL;
 		goto got_it;
@@ -567,7 +567,7 @@ again:
 	h->transid = cur_trans->transid;
 	h->transaction = cur_trans;
 	h->root = root;
-	h->use_count = 1;
+	refcount_set(&h->use_count, 1);
 	h->fs_info = root->fs_info;
 
 	h->type = type;
@@ -837,8 +837,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 	int err = 0;
 	int must_run_delayed_refs = 0;
 
-	if (trans->use_count > 1) {
-		trans->use_count--;
+	if (refcount_read(&trans->use_count) > 1) {
+		refcount_dec(&trans->use_count);
 		trans->block_rsv = trans->orig_rsv;
 		return 0;
 	}
@@ -1016,8 +1016,7 @@ static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
 		 * it's safe to do it (through clear_btree_io_tree()).
 		 */
 		err = clear_extent_bit(dirty_pages, start, end,
-				       EXTENT_NEED_WAIT,
-				       0, 0, &cached_state, GFP_NOFS);
+				       EXTENT_NEED_WAIT, 0, 0, &cached_state);
 		if (err == -ENOMEM)
 			err = 0;
 		if (!err)
@@ -1869,7 +1868,7 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
 	struct btrfs_transaction *cur_trans = trans->transaction;
 	DEFINE_WAIT(wait);
 
-	WARN_ON(trans->use_count > 1);
+	WARN_ON(refcount_read(&trans->use_count) > 1);
 
 	btrfs_abort_transaction(trans, err);
 
@@ -2266,16 +2265,13 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 	}
 
 	ret = write_all_supers(fs_info, 0);
-	if (ret) {
-		mutex_unlock(&fs_info->tree_log_mutex);
-		goto scrub_continue;
-	}
-
 	/*
 	 * the super is written, we can safely allow the tree-loggers
 	 * to go about their business
 	 */
 	mutex_unlock(&fs_info->tree_log_mutex);
+	if (ret)
+		goto scrub_continue;
 
 	btrfs_finish_extent_commit(trans, fs_info);
 
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index c55e44560103..6beee072b1bd 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -58,6 +58,7 @@ struct btrfs_transaction {
 
 	/* Be protected by fs_info->trans_lock when we want to change it. */
 	enum btrfs_trans_state state;
+	int aborted;
 	struct list_head list;
 	struct extent_io_tree dirty_pages;
 	unsigned long start_time;
@@ -70,7 +71,6 @@ struct btrfs_transaction {
 	struct list_head dirty_bgs;
 	struct list_head io_bgs;
 	struct list_head dropped_roots;
-	u64 num_dirty_bgs;
 
 	/*
 	 * we need to make sure block group deletion doesn't race with
@@ -79,11 +79,11 @@ struct btrfs_transaction {
 	 */
 	struct mutex cache_write_mutex;
 	spinlock_t dirty_bgs_lock;
+	unsigned int num_dirty_bgs;
 	/* Protected by spin lock fs_info->unused_bgs_lock. */
 	struct list_head deleted_bgs;
 	spinlock_t dropped_roots_lock;
 	struct btrfs_delayed_ref_root delayed_refs;
-	int aborted;
 	struct btrfs_fs_info *fs_info;
 };
 
@@ -111,20 +111,19 @@ struct btrfs_trans_handle {
 	u64 transid;
 	u64 bytes_reserved;
 	u64 chunk_bytes_reserved;
-	unsigned long use_count;
-	unsigned long blocks_reserved;
 	unsigned long delayed_ref_updates;
 	struct btrfs_transaction *transaction;
 	struct btrfs_block_rsv *block_rsv;
 	struct btrfs_block_rsv *orig_rsv;
+	refcount_t use_count;
+	unsigned int type;
 	short aborted;
-	short adding_csums;
+	bool adding_csums;
 	bool allocating_chunk;
 	bool can_flush_pending_bgs;
 	bool reloc_reserved;
 	bool sync;
 	bool dirty;
-	unsigned int type;
 	struct btrfs_root *root;
 	struct btrfs_fs_info *fs_info;
 	struct list_head new_bgs;
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index ce4ed6ec8f39..c3c8d48f6618 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -30,6 +30,7 @@
 #include "tree-checker.h"
 #include "disk-io.h"
 #include "compression.h"
+#include "hash.h"
 
 /*
  * Error message should follow the following format:
@@ -223,6 +224,142 @@ static int check_csum_item(struct btrfs_root *root, struct extent_buffer *leaf,
 }
 
 /*
+ * Customized reported for dir_item, only important new info is key->objectid,
+ * which represents inode number
+ */
+__printf(4, 5)
+static void dir_item_err(const struct btrfs_root *root,
+			 const struct extent_buffer *eb, int slot,
+			 const char *fmt, ...)
+{
+	struct btrfs_key key;
+	struct va_format vaf;
+	va_list args;
+
+	btrfs_item_key_to_cpu(eb, &key, slot);
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	btrfs_crit(root->fs_info,
+	"corrupt %s: root=%llu block=%llu slot=%d ino=%llu, %pV",
+		btrfs_header_level(eb) == 0 ? "leaf" : "node", root->objectid,
+		btrfs_header_bytenr(eb), slot, key.objectid, &vaf);
+	va_end(args);
+}
+
+static int check_dir_item(struct btrfs_root *root,
+			  struct extent_buffer *leaf,
+			  struct btrfs_key *key, int slot)
+{
+	struct btrfs_dir_item *di;
+	u32 item_size = btrfs_item_size_nr(leaf, slot);
+	u32 cur = 0;
+
+	di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+	while (cur < item_size) {
+		u32 name_len;
+		u32 data_len;
+		u32 max_name_len;
+		u32 total_size;
+		u32 name_hash;
+		u8 dir_type;
+
+		/* header itself should not cross item boundary */
+		if (cur + sizeof(*di) > item_size) {
+			dir_item_err(root, leaf, slot,
+		"dir item header crosses item boundary, have %zu boundary %u",
+				cur + sizeof(*di), item_size);
+			return -EUCLEAN;
+		}
+
+		/* dir type check */
+		dir_type = btrfs_dir_type(leaf, di);
+		if (dir_type >= BTRFS_FT_MAX) {
+			dir_item_err(root, leaf, slot,
+			"invalid dir item type, have %u expect [0, %u)",
+				dir_type, BTRFS_FT_MAX);
+			return -EUCLEAN;
+		}
+
+		if (key->type == BTRFS_XATTR_ITEM_KEY &&
+		    dir_type != BTRFS_FT_XATTR) {
+			dir_item_err(root, leaf, slot,
+		"invalid dir item type for XATTR key, have %u expect %u",
+				dir_type, BTRFS_FT_XATTR);
+			return -EUCLEAN;
+		}
+		if (dir_type == BTRFS_FT_XATTR &&
+		    key->type != BTRFS_XATTR_ITEM_KEY) {
+			dir_item_err(root, leaf, slot,
+			"xattr dir type found for non-XATTR key");
+			return -EUCLEAN;
+		}
+		if (dir_type == BTRFS_FT_XATTR)
+			max_name_len = XATTR_NAME_MAX;
+		else
+			max_name_len = BTRFS_NAME_LEN;
+
+		/* Name/data length check */
+		name_len = btrfs_dir_name_len(leaf, di);
+		data_len = btrfs_dir_data_len(leaf, di);
+		if (name_len > max_name_len) {
+			dir_item_err(root, leaf, slot,
+			"dir item name len too long, have %u max %u",
+				name_len, max_name_len);
+			return -EUCLEAN;
+		}
+		if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info)) {
+			dir_item_err(root, leaf, slot,
+			"dir item name and data len too long, have %u max %u",
+				name_len + data_len,
+				BTRFS_MAX_XATTR_SIZE(root->fs_info));
+			return -EUCLEAN;
+		}
+
+		if (data_len && dir_type != BTRFS_FT_XATTR) {
+			dir_item_err(root, leaf, slot,
+			"dir item with invalid data len, have %u expect 0",
+				data_len);
+			return -EUCLEAN;
+		}
+
+		total_size = sizeof(*di) + name_len + data_len;
+
+		/* header and name/data should not cross item boundary */
+		if (cur + total_size > item_size) {
+			dir_item_err(root, leaf, slot,
+		"dir item data crosses item boundary, have %u boundary %u",
+				cur + total_size, item_size);
+			return -EUCLEAN;
+		}
+
+		/*
+		 * Special check for XATTR/DIR_ITEM, as key->offset is name
+		 * hash, should match its name
+		 */
+		if (key->type == BTRFS_DIR_ITEM_KEY ||
+		    key->type == BTRFS_XATTR_ITEM_KEY) {
+			char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+
+			read_extent_buffer(leaf, namebuf,
+					(unsigned long)(di + 1), name_len);
+			name_hash = btrfs_name_hash(namebuf, name_len);
+			if (key->offset != name_hash) {
+				dir_item_err(root, leaf, slot,
+		"name hash mismatch with key, have 0x%016x expect 0x%016llx",
+					name_hash, key->offset);
+				return -EUCLEAN;
+			}
+		}
+		cur += total_size;
+		di = (struct btrfs_dir_item *)((void *)di + total_size);
+	}
+	return 0;
+}
+
+/*
  * Common point to switch the item-specific validation.
  */
 static int check_leaf_item(struct btrfs_root *root,
@@ -238,6 +375,11 @@ static int check_leaf_item(struct btrfs_root *root,
 	case BTRFS_EXTENT_CSUM_KEY:
 		ret = check_csum_item(root, leaf, key, slot);
 		break;
+	case BTRFS_DIR_ITEM_KEY:
+	case BTRFS_DIR_INDEX_KEY:
+	case BTRFS_XATTR_ITEM_KEY:
+		ret = check_dir_item(root, leaf, key, slot);
+		break;
 	}
 	return ret;
 }
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 1b7d92075c1f..afadaadab18e 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1174,19 +1174,15 @@ next:
 	return 0;
 }
 
-static int extref_get_fields(struct extent_buffer *eb, int slot,
-			     unsigned long ref_ptr, u32 *namelen, char **name,
-			     u64 *index, u64 *parent_objectid)
+static int extref_get_fields(struct extent_buffer *eb, unsigned long ref_ptr,
+			     u32 *namelen, char **name, u64 *index,
+			     u64 *parent_objectid)
 {
 	struct btrfs_inode_extref *extref;
 
 	extref = (struct btrfs_inode_extref *)ref_ptr;
 
 	*namelen = btrfs_inode_extref_name_len(eb, extref);
-	if (!btrfs_is_name_len_valid(eb, slot, (unsigned long)&extref->name,
-				     *namelen))
-		return -EIO;
-
 	*name = kmalloc(*namelen, GFP_NOFS);
 	if (*name == NULL)
 		return -ENOMEM;
@@ -1201,19 +1197,14 @@ static int extref_get_fields(struct extent_buffer *eb, int slot,
 	return 0;
 }
 
-static int ref_get_fields(struct extent_buffer *eb, int slot,
-			  unsigned long ref_ptr, u32 *namelen, char **name,
-			  u64 *index)
+static int ref_get_fields(struct extent_buffer *eb, unsigned long ref_ptr,
+			  u32 *namelen, char **name, u64 *index)
 {
 	struct btrfs_inode_ref *ref;
 
 	ref = (struct btrfs_inode_ref *)ref_ptr;
 
 	*namelen = btrfs_inode_ref_name_len(eb, ref);
-	if (!btrfs_is_name_len_valid(eb, slot, (unsigned long)(ref + 1),
-				     *namelen))
-		return -EIO;
-
 	*name = kmalloc(*namelen, GFP_NOFS);
 	if (*name == NULL)
 		return -ENOMEM;
@@ -1288,8 +1279,8 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
 
 	while (ref_ptr < ref_end) {
 		if (log_ref_ver) {
-			ret = extref_get_fields(eb, slot, ref_ptr, &namelen,
-					  &name, &ref_index, &parent_objectid);
+			ret = extref_get_fields(eb, ref_ptr, &namelen, &name,
+						&ref_index, &parent_objectid);
 			/*
 			 * parent object can change from one array
 			 * item to another.
@@ -1301,8 +1292,8 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
 				goto out;
 			}
 		} else {
-			ret = ref_get_fields(eb, slot, ref_ptr, &namelen,
-					     &name, &ref_index);
+			ret = ref_get_fields(eb, ref_ptr, &namelen, &name,
+					     &ref_index);
 		}
 		if (ret)
 			goto out;
@@ -1836,7 +1827,6 @@ static noinline int replay_one_dir_item(struct btrfs_trans_handle *trans,
 					struct extent_buffer *eb, int slot,
 					struct btrfs_key *key)
 {
-	struct btrfs_fs_info *fs_info = root->fs_info;
 	int ret = 0;
 	u32 item_size = btrfs_item_size_nr(eb, slot);
 	struct btrfs_dir_item *di;
@@ -1849,8 +1839,6 @@ static noinline int replay_one_dir_item(struct btrfs_trans_handle *trans,
 	ptr_end = ptr + item_size;
 	while (ptr < ptr_end) {
 		di = (struct btrfs_dir_item *)ptr;
-		if (verify_dir_item(fs_info, eb, slot, di))
-			return -EIO;
 		name_len = btrfs_dir_name_len(eb, di);
 		ret = replay_one_name(trans, root, path, eb, di, key);
 		if (ret < 0)
@@ -2025,11 +2013,6 @@ again:
 	ptr_end = ptr + item_size;
 	while (ptr < ptr_end) {
 		di = (struct btrfs_dir_item *)ptr;
-		if (verify_dir_item(fs_info, eb, slot, di)) {
-			ret = -EIO;
-			goto out;
-		}
-
 		name_len = btrfs_dir_name_len(eb, di);
 		name = kmalloc(name_len, GFP_NOFS);
 		if (!name) {
@@ -2110,7 +2093,6 @@ static int replay_xattr_deletes(struct btrfs_trans_handle *trans,
 			      struct btrfs_path *path,
 			      const u64 ino)
 {
-	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct btrfs_key search_key;
 	struct btrfs_path *log_path;
 	int i;
@@ -2152,11 +2134,6 @@ process_leaf:
 			u32 this_len = sizeof(*di) + name_len + data_len;
 			char *name;
 
-			ret = verify_dir_item(fs_info, path->nodes[0], i, di);
-			if (ret) {
-				ret = -EIO;
-				goto out;
-			}
 			name = kmalloc(name_len, GFP_NOFS);
 			if (!name) {
 				ret = -ENOMEM;
@@ -4574,12 +4551,6 @@ static int btrfs_check_ref_name_override(struct extent_buffer *eb,
 			this_len = sizeof(*extref) + this_name_len;
 		}
 
-		ret = btrfs_is_name_len_valid(eb, slot, name_ptr,
-					      this_name_len);
-		if (!ret) {
-			ret = -EIO;
-			goto out;
-		}
 		if (this_name_len > name_len) {
 			char *new_name;
 
@@ -5434,11 +5405,10 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 				  struct dentry *parent,
 				  const loff_t start,
 				  const loff_t end,
-				  int exists_only,
+				  int inode_only,
 				  struct btrfs_log_ctx *ctx)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
-	int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
 	struct super_block *sb;
 	struct dentry *old_parent = NULL;
 	int ret = 0;
@@ -5604,7 +5574,7 @@ int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
 	int ret;
 
 	ret = btrfs_log_inode_parent(trans, root, BTRFS_I(d_inode(dentry)),
-			parent, start, end, 0, ctx);
+			parent, start, end, LOG_INODE_ALL, ctx);
 	dput(parent);
 
 	return ret;
@@ -5867,6 +5837,6 @@ int btrfs_log_new_name(struct btrfs_trans_handle *trans,
 		return 0;
 
 	return btrfs_log_inode_parent(trans, root, inode, parent, 0,
-				      LLONG_MAX, 1, NULL);
+				      LLONG_MAX, LOG_INODE_EXISTS, NULL);
 }
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a25684287501..b5036bd69e6a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -145,6 +145,71 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 			     struct btrfs_bio **bbio_ret,
 			     int mirror_num, int need_raid_map);
 
+/*
+ * Device locking
+ * ==============
+ *
+ * There are several mutexes that protect manipulation of devices and low-level
+ * structures like chunks but not block groups, extents or files
+ *
+ * uuid_mutex (global lock)
+ * ------------------------
+ * protects the fs_uuids list that tracks all per-fs fs_devices, resulting from
+ * the SCAN_DEV ioctl registration or from mount either implicitly (the first
+ * device) or requested by the device= mount option
+ *
+ * the mutex can be very coarse and can cover long-running operations
+ *
+ * protects: updates to fs_devices counters like missing devices, rw devices,
+ * seeding, structure cloning, openning/closing devices at mount/umount time
+ *
+ * global::fs_devs - add, remove, updates to the global list
+ *
+ * does not protect: manipulation of the fs_devices::devices list!
+ *
+ * btrfs_device::name - renames (write side), read is RCU
+ *
+ * fs_devices::device_list_mutex (per-fs, with RCU)
+ * ------------------------------------------------
+ * protects updates to fs_devices::devices, ie. adding and deleting
+ *
+ * simple list traversal with read-only actions can be done with RCU protection
+ *
+ * may be used to exclude some operations from running concurrently without any
+ * modifications to the list (see write_all_supers)
+ *
+ * volume_mutex
+ * ------------
+ * coarse lock owned by a mounted filesystem; used to exclude some operations
+ * that cannot run in parallel and affect the higher-level properties of the
+ * filesystem like: device add/deleting/resize/replace, or balance
+ *
+ * balance_mutex
+ * -------------
+ * protects balance structures (status, state) and context accessed from
+ * several places (internally, ioctl)
+ *
+ * chunk_mutex
+ * -----------
+ * protects chunks, adding or removing during allocation, trim or when a new
+ * device is added/removed
+ *
+ * cleaner_mutex
+ * -------------
+ * a big lock that is held by the cleaner thread and prevents running subvolume
+ * cleaning together with relocation or delayed iputs
+ *
+ *
+ * Lock nesting
+ * ============
+ *
+ * uuid_mutex
+ *   volume_mutex
+ *     device_list_mutex
+ *       chunk_mutex
+ *     balance_mutex
+ */
+
 DEFINE_MUTEX(uuid_mutex);
 static LIST_HEAD(fs_uuids);
 struct list_head *btrfs_get_fs_uuids(void)
@@ -180,6 +245,13 @@ static struct btrfs_fs_devices *alloc_fs_devices(const u8 *fsid)
 	return fs_devs;
 }
 
+static void free_device(struct btrfs_device *device)
+{
+	rcu_string_free(device->name);
+	bio_put(device->flush_bio);
+	kfree(device);
+}
+
 static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
 {
 	struct btrfs_device *device;
@@ -188,9 +260,7 @@ static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
 		device = list_entry(fs_devices->devices.next,
 				    struct btrfs_device, dev_list);
 		list_del(&device->dev_list);
-		rcu_string_free(device->name);
-		bio_put(device->flush_bio);
-		kfree(device);
+		free_device(device);
 	}
 	kfree(fs_devices);
 }
@@ -220,6 +290,11 @@ void btrfs_cleanup_fs_uuids(void)
 	}
 }
 
+/*
+ * Returns a pointer to a new btrfs_device on success; ERR_PTR() on error.
+ * Returned struct is not linked onto any lists and must be destroyed using
+ * free_device.
+ */
 static struct btrfs_device *__alloc_device(void)
 {
 	struct btrfs_device *dev;
@@ -244,7 +319,6 @@ static struct btrfs_device *__alloc_device(void)
 
 	spin_lock_init(&dev->io_lock);
 
-	spin_lock_init(&dev->reada_lock);
 	atomic_set(&dev->reada_in_flight, 0);
 	atomic_set(&dev->dev_stats_ccnt, 0);
 	btrfs_device_data_ordered_init(dev);
@@ -530,45 +604,42 @@ static void pending_bios_fn(struct btrfs_work *work)
 	run_scheduled_bios(device);
 }
 
-
-static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
+/*
+ *  Search and remove all stale (devices which are not mounted) devices.
+ *  When both inputs are NULL, it will search and release all stale devices.
+ *  path:	Optional. When provided will it release all unmounted devices
+ *		matching this path only.
+ *  skip_dev:	Optional. Will skip this device when searching for the stale
+ *		devices.
+ */
+static void btrfs_free_stale_devices(const char *path,
+				     struct btrfs_device *skip_dev)
 {
-	struct btrfs_fs_devices *fs_devs;
-	struct btrfs_device *dev;
-
-	if (!cur_dev->name)
-		return;
+	struct btrfs_fs_devices *fs_devs, *tmp_fs_devs;
+	struct btrfs_device *dev, *tmp_dev;
 
-	list_for_each_entry(fs_devs, &fs_uuids, list) {
-		int del = 1;
+	list_for_each_entry_safe(fs_devs, tmp_fs_devs, &fs_uuids, list) {
 
 		if (fs_devs->opened)
 			continue;
-		if (fs_devs->seeding)
-			continue;
 
-		list_for_each_entry(dev, &fs_devs->devices, dev_list) {
+		list_for_each_entry_safe(dev, tmp_dev,
+					 &fs_devs->devices, dev_list) {
+			int not_found = 0;
 
-			if (dev == cur_dev)
+			if (skip_dev && skip_dev == dev)
 				continue;
-			if (!dev->name)
+			if (path && !dev->name)
 				continue;
 
-			/*
-			 * Todo: This won't be enough. What if the same device
-			 * comes back (with new uuid and) with its mapper path?
-			 * But for now, this does help as mostly an admin will
-			 * either use mapper or non mapper path throughout.
-			 */
 			rcu_read_lock();
-			del = strcmp(rcu_str_deref(dev->name),
-						rcu_str_deref(cur_dev->name));
+			if (path)
+				not_found = strcmp(rcu_str_deref(dev->name),
+						   path);
 			rcu_read_unlock();
-			if (!del)
-				break;
-		}
+			if (not_found)
+				continue;
 
-		if (!del) {
 			/* delete the stale device */
 			if (fs_devs->num_devices == 1) {
 				btrfs_sysfs_remove_fsid(fs_devs);
@@ -577,38 +648,99 @@ static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
 			} else {
 				fs_devs->num_devices--;
 				list_del(&dev->dev_list);
-				rcu_string_free(dev->name);
-				bio_put(dev->flush_bio);
-				kfree(dev);
+				free_device(dev);
 			}
-			break;
 		}
 	}
 }
 
+static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
+			struct btrfs_device *device, fmode_t flags,
+			void *holder)
+{
+	struct request_queue *q;
+	struct block_device *bdev;
+	struct buffer_head *bh;
+	struct btrfs_super_block *disk_super;
+	u64 devid;
+	int ret;
+
+	if (device->bdev)
+		return -EINVAL;
+	if (!device->name)
+		return -EINVAL;
+
+	ret = btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1,
+				    &bdev, &bh);
+	if (ret)
+		return ret;
+
+	disk_super = (struct btrfs_super_block *)bh->b_data;
+	devid = btrfs_stack_device_id(&disk_super->dev_item);
+	if (devid != device->devid)
+		goto error_brelse;
+
+	if (memcmp(device->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE))
+		goto error_brelse;
+
+	device->generation = btrfs_super_generation(disk_super);
+
+	if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING) {
+		clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
+		fs_devices->seeding = 1;
+	} else {
+		if (bdev_read_only(bdev))
+			clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
+		else
+			set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
+	}
+
+	q = bdev_get_queue(bdev);
+	if (!blk_queue_nonrot(q))
+		fs_devices->rotating = 1;
+
+	device->bdev = bdev;
+	clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
+	device->mode = flags;
+
+	fs_devices->open_devices++;
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
+	    device->devid != BTRFS_DEV_REPLACE_DEVID) {
+		fs_devices->rw_devices++;
+		list_add(&device->dev_alloc_list, &fs_devices->alloc_list);
+	}
+	brelse(bh);
+
+	return 0;
+
+error_brelse:
+	brelse(bh);
+	blkdev_put(bdev, flags);
+
+	return -EINVAL;
+}
+
 /*
  * Add new device to list of registered devices
  *
  * Returns:
- * 1   - first time device is seen
- * 0   - device already known
- * < 0 - error
+ * device pointer which was just added or updated when successful
+ * error pointer when failed
  */
-static noinline int device_list_add(const char *path,
-			   struct btrfs_super_block *disk_super,
-			   u64 devid, struct btrfs_fs_devices **fs_devices_ret)
+static noinline struct btrfs_device *device_list_add(const char *path,
+			   struct btrfs_super_block *disk_super)
 {
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *fs_devices;
 	struct rcu_string *name;
-	int ret = 0;
 	u64 found_transid = btrfs_super_generation(disk_super);
+	u64 devid = btrfs_stack_device_id(&disk_super->dev_item);
 
 	fs_devices = find_fsid(disk_super->fsid);
 	if (!fs_devices) {
 		fs_devices = alloc_fs_devices(disk_super->fsid);
 		if (IS_ERR(fs_devices))
-			return PTR_ERR(fs_devices);
+			return ERR_CAST(fs_devices);
 
 		list_add(&fs_devices->list, &fs_uuids);
 
@@ -620,20 +752,19 @@ static noinline int device_list_add(const char *path,
 
 	if (!device) {
 		if (fs_devices->opened)
-			return -EBUSY;
+			return ERR_PTR(-EBUSY);
 
 		device = btrfs_alloc_device(NULL, &devid,
 					    disk_super->dev_item.uuid);
 		if (IS_ERR(device)) {
 			/* we can safely leave the fs_devices entry around */
-			return PTR_ERR(device);
+			return device;
 		}
 
 		name = rcu_string_strdup(path, GFP_NOFS);
 		if (!name) {
-			bio_put(device->flush_bio);
-			kfree(device);
-			return -ENOMEM;
+			free_device(device);
+			return ERR_PTR(-ENOMEM);
 		}
 		rcu_assign_pointer(device->name, name);
 
@@ -642,8 +773,16 @@ static noinline int device_list_add(const char *path,
 		fs_devices->num_devices++;
 		mutex_unlock(&fs_devices->device_list_mutex);
 
-		ret = 1;
 		device->fs_devices = fs_devices;
+		btrfs_free_stale_devices(path, device);
+
+		if (disk_super->label[0])
+			pr_info("BTRFS: device label %s devid %llu transid %llu %s\n",
+				disk_super->label, devid, found_transid, path);
+		else
+			pr_info("BTRFS: device fsid %pU devid %llu transid %llu %s\n",
+				disk_super->fsid, devid, found_transid, path);
+
 	} else if (!device->name || strcmp(device->name->str, path)) {
 		/*
 		 * When FS is already mounted.
@@ -679,17 +818,17 @@ static noinline int device_list_add(const char *path,
 			 * with larger generation number or the last-in if
 			 * generation are equal.
 			 */
-			return -EEXIST;
+			return ERR_PTR(-EEXIST);
 		}
 
 		name = rcu_string_strdup(path, GFP_NOFS);
 		if (!name)
-			return -ENOMEM;
+			return ERR_PTR(-ENOMEM);
 		rcu_string_free(device->name);
 		rcu_assign_pointer(device->name, name);
-		if (device->missing) {
+		if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
 			fs_devices->missing_devices--;
-			device->missing = 0;
+			clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);
 		}
 	}
 
@@ -702,16 +841,9 @@ static noinline int device_list_add(const char *path,
 	if (!fs_devices->opened)
 		device->generation = found_transid;
 
-	/*
-	 * if there is new btrfs on an already registered device,
-	 * then remove the stale device entry.
-	 */
-	if (ret > 0)
-		btrfs_free_stale_device(device);
-
-	*fs_devices_ret = fs_devices;
+	fs_devices->total_devices = btrfs_super_num_devices(disk_super);
 
-	return ret;
+	return device;
 }
 
 static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
@@ -744,8 +876,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
 			name = rcu_string_strdup(orig_dev->name->str,
 					GFP_KERNEL);
 			if (!name) {
-				bio_put(device->flush_bio);
-				kfree(device);
+				free_device(device);
 				goto error;
 			}
 			rcu_assign_pointer(device->name, name);
@@ -772,10 +903,12 @@ void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices, int step)
 again:
 	/* This is the initialized path, it is safe to release the devices. */
 	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
-		if (device->in_fs_metadata) {
-			if (!device->is_tgtdev_for_dev_replace &&
-			    (!latest_dev ||
-			     device->generation > latest_dev->generation)) {
+		if (test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+							&device->dev_state)) {
+			if (!test_bit(BTRFS_DEV_STATE_REPLACE_TGT,
+			     &device->dev_state) &&
+			     (!latest_dev ||
+			      device->generation > latest_dev->generation)) {
 				latest_dev = device;
 			}
 			continue;
@@ -792,7 +925,8 @@ again:
 			 * not, which means whether this device is
 			 * used or whether it should be removed.
 			 */
-			if (step == 0 || device->is_tgtdev_for_dev_replace) {
+			if (step == 0 || test_bit(BTRFS_DEV_STATE_REPLACE_TGT,
+						  &device->dev_state)) {
 				continue;
 			}
 		}
@@ -801,17 +935,16 @@ again:
 			device->bdev = NULL;
 			fs_devices->open_devices--;
 		}
-		if (device->writeable) {
+		if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 			list_del_init(&device->dev_alloc_list);
-			device->writeable = 0;
-			if (!device->is_tgtdev_for_dev_replace)
+			clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
+			if (!test_bit(BTRFS_DEV_STATE_REPLACE_TGT,
+				      &device->dev_state))
 				fs_devices->rw_devices--;
 		}
 		list_del_init(&device->dev_list);
 		fs_devices->num_devices--;
-		rcu_string_free(device->name);
-		bio_put(device->flush_bio);
-		kfree(device);
+		free_device(device);
 	}
 
 	if (fs_devices->seed) {
@@ -824,35 +957,25 @@ again:
 	mutex_unlock(&uuid_mutex);
 }
 
-static void __free_device(struct work_struct *work)
-{
-	struct btrfs_device *device;
-
-	device = container_of(work, struct btrfs_device, rcu_work);
-	rcu_string_free(device->name);
-	bio_put(device->flush_bio);
-	kfree(device);
-}
-
-static void free_device(struct rcu_head *head)
+static void free_device_rcu(struct rcu_head *head)
 {
 	struct btrfs_device *device;
 
 	device = container_of(head, struct btrfs_device, rcu);
-
-	INIT_WORK(&device->rcu_work, __free_device);
-	schedule_work(&device->rcu_work);
+	free_device(device);
 }
 
 static void btrfs_close_bdev(struct btrfs_device *device)
 {
-	if (device->bdev && device->writeable) {
+	if (!device->bdev)
+		return;
+
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 		sync_blockdev(device->bdev);
 		invalidate_bdev(device->bdev);
 	}
 
-	if (device->bdev)
-		blkdev_put(device->bdev, device->mode);
+	blkdev_put(device->bdev, device->mode);
 }
 
 static void btrfs_prepare_close_one_device(struct btrfs_device *device)
@@ -864,13 +987,13 @@ static void btrfs_prepare_close_one_device(struct btrfs_device *device)
 	if (device->bdev)
 		fs_devices->open_devices--;
 
-	if (device->writeable &&
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
 	    device->devid != BTRFS_DEV_REPLACE_DEVID) {
 		list_del_init(&device->dev_alloc_list);
 		fs_devices->rw_devices--;
 	}
 
-	if (device->missing)
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 		fs_devices->missing_devices--;
 
 	new_device = btrfs_alloc_device(NULL, &device->devid,
@@ -916,7 +1039,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 				struct btrfs_device, dev_list);
 		list_del(&device->dev_list);
 		btrfs_close_bdev(device);
-		call_rcu(&device->rcu, free_device);
+		call_rcu(&device->rcu, free_device_rcu);
 	}
 
 	WARN_ON(fs_devices->open_devices);
@@ -946,93 +1069,32 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 		__btrfs_close_devices(fs_devices);
 		free_fs_devices(fs_devices);
 	}
-	/*
-	 * Wait for rcu kworkers under __btrfs_close_devices
-	 * to finish all blkdev_puts so device is really
-	 * free when umount is done.
-	 */
-	rcu_barrier();
 	return ret;
 }
 
 static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 				fmode_t flags, void *holder)
 {
-	struct request_queue *q;
-	struct block_device *bdev;
 	struct list_head *head = &fs_devices->devices;
 	struct btrfs_device *device;
 	struct btrfs_device *latest_dev = NULL;
-	struct buffer_head *bh;
-	struct btrfs_super_block *disk_super;
-	u64 devid;
-	int seeding = 1;
 	int ret = 0;
 
 	flags |= FMODE_EXCL;
 
 	list_for_each_entry(device, head, dev_list) {
-		if (device->bdev)
-			continue;
-		if (!device->name)
-			continue;
-
 		/* Just open everything we can; ignore failures here */
-		if (btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1,
-					    &bdev, &bh))
+		if (btrfs_open_one_device(fs_devices, device, flags, holder))
 			continue;
 
-		disk_super = (struct btrfs_super_block *)bh->b_data;
-		devid = btrfs_stack_device_id(&disk_super->dev_item);
-		if (devid != device->devid)
-			goto error_brelse;
-
-		if (memcmp(device->uuid, disk_super->dev_item.uuid,
-			   BTRFS_UUID_SIZE))
-			goto error_brelse;
-
-		device->generation = btrfs_super_generation(disk_super);
 		if (!latest_dev ||
 		    device->generation > latest_dev->generation)
 			latest_dev = device;
-
-		if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING) {
-			device->writeable = 0;
-		} else {
-			device->writeable = !bdev_read_only(bdev);
-			seeding = 0;
-		}
-
-		q = bdev_get_queue(bdev);
-		if (blk_queue_discard(q))
-			device->can_discard = 1;
-		if (!blk_queue_nonrot(q))
-			fs_devices->rotating = 1;
-
-		device->bdev = bdev;
-		device->in_fs_metadata = 0;
-		device->mode = flags;
-
-		fs_devices->open_devices++;
-		if (device->writeable &&
-		    device->devid != BTRFS_DEV_REPLACE_DEVID) {
-			fs_devices->rw_devices++;
-			list_add(&device->dev_alloc_list,
-				 &fs_devices->alloc_list);
-		}
-		brelse(bh);
-		continue;
-
-error_brelse:
-		brelse(bh);
-		blkdev_put(bdev, flags);
-		continue;
 	}
 	if (fs_devices->open_devices == 0) {
 		ret = -EINVAL;
 		goto out;
 	}
-	fs_devices->seeding = seeding;
 	fs_devices->opened = 1;
 	fs_devices->latest_bdev = latest_dev->bdev;
 	fs_devices->total_rw_bytes = 0;
@@ -1116,12 +1178,10 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 			  struct btrfs_fs_devices **fs_devices_ret)
 {
 	struct btrfs_super_block *disk_super;
+	struct btrfs_device *device;
 	struct block_device *bdev;
 	struct page *page;
-	int ret = -EINVAL;
-	u64 devid;
-	u64 transid;
-	u64 total_devices;
+	int ret = 0;
 	u64 bytenr;
 
 	/*
@@ -1140,26 +1200,16 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 		goto error;
 	}
 
-	if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super))
+	if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super)) {
+		ret = -EINVAL;
 		goto error_bdev_put;
-
-	devid = btrfs_stack_device_id(&disk_super->dev_item);
-	transid = btrfs_super_generation(disk_super);
-	total_devices = btrfs_super_num_devices(disk_super);
-
-	ret = device_list_add(path, disk_super, devid, fs_devices_ret);
-	if (ret > 0) {
-		if (disk_super->label[0]) {
-			pr_info("BTRFS: device label %s ", disk_super->label);
-		} else {
-			pr_info("BTRFS: device fsid %pU ", disk_super->fsid);
-		}
-
-		pr_cont("devid %llu transid %llu %s\n", devid, transid, path);
-		ret = 0;
 	}
-	if (!ret && fs_devices_ret)
-		(*fs_devices_ret)->total_devices = total_devices;
+
+	device = device_list_add(path, disk_super);
+	if (IS_ERR(device))
+		ret = PTR_ERR(device);
+	else
+		*fs_devices_ret = device->fs_devices;
 
 	btrfs_release_disk_super(page);
 
@@ -1185,7 +1235,8 @@ int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
 
 	*length = 0;
 
-	if (start >= device->total_bytes || device->is_tgtdev_for_dev_replace)
+	if (start >= device->total_bytes ||
+		test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
 		return 0;
 
 	path = btrfs_alloc_path();
@@ -1363,7 +1414,8 @@ int find_free_dev_extent_start(struct btrfs_transaction *transaction,
 	max_hole_size = 0;
 
 again:
-	if (search_start >= search_end || device->is_tgtdev_for_dev_replace) {
+	if (search_start >= search_end ||
+		test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
 		ret = -ENOSPC;
 		goto out;
 	}
@@ -1570,8 +1622,8 @@ static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	struct btrfs_key key;
 
-	WARN_ON(!device->in_fs_metadata);
-	WARN_ON(device->is_tgtdev_for_dev_replace);
+	WARN_ON(!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state));
+	WARN_ON(test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state));
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
@@ -1661,7 +1713,7 @@ error:
  * the device information is stored in the chunk root
  * the btrfs_device struct should be fully filled in
  */
-static int btrfs_add_device(struct btrfs_trans_handle *trans,
+static int btrfs_add_dev_item(struct btrfs_trans_handle *trans,
 			    struct btrfs_fs_info *fs_info,
 			    struct btrfs_device *device)
 {
@@ -1817,7 +1869,8 @@ static struct btrfs_device * btrfs_find_next_active_device(
 
 	list_for_each_entry(next_device, &fs_devs->devices, dev_list) {
 		if (next_device != device &&
-			!next_device->missing && next_device->bdev)
+		    !test_bit(BTRFS_DEV_STATE_MISSING, &next_device->dev_state)
+		    && next_device->bdev)
 			return next_device;
 	}
 
@@ -1858,6 +1911,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	u64 num_devices;
 	int ret = 0;
 
+	mutex_lock(&fs_info->volume_mutex);
 	mutex_lock(&uuid_mutex);
 
 	num_devices = fs_info->fs_devices->num_devices;
@@ -1877,17 +1931,18 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	if (ret)
 		goto out;
 
-	if (device->is_tgtdev_for_dev_replace) {
+	if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
 		ret = BTRFS_ERROR_DEV_TGT_REPLACE;
 		goto out;
 	}
 
-	if (device->writeable && fs_info->fs_devices->rw_devices == 1) {
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
+	    fs_info->fs_devices->rw_devices == 1) {
 		ret = BTRFS_ERROR_DEV_ONLY_WRITABLE;
 		goto out;
 	}
 
-	if (device->writeable) {
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 		mutex_lock(&fs_info->chunk_mutex);
 		list_del_init(&device->dev_alloc_list);
 		device->fs_devices->rw_devices--;
@@ -1909,7 +1964,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	if (ret)
 		goto error_undo;
 
-	device->in_fs_metadata = 0;
+	clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 	btrfs_scrub_cancel_dev(fs_info, device);
 
 	/*
@@ -1929,7 +1984,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	device->fs_devices->num_devices--;
 	device->fs_devices->total_devices--;
 
-	if (device->missing)
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 		device->fs_devices->missing_devices--;
 
 	btrfs_assign_next_active_device(fs_info, device, NULL);
@@ -1949,11 +2004,11 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	 * the devices list.  All that's left is to zero out the old
 	 * supers and free the device.
 	 */
-	if (device->writeable)
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
 		btrfs_scratch_superblocks(device->bdev, device->name->str);
 
 	btrfs_close_bdev(device);
-	call_rcu(&device->rcu, free_device);
+	call_rcu(&device->rcu, free_device_rcu);
 
 	if (cur_devices->open_devices == 0) {
 		struct btrfs_fs_devices *fs_devices;
@@ -1972,10 +2027,11 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 
 out:
 	mutex_unlock(&uuid_mutex);
+	mutex_unlock(&fs_info->volume_mutex);
 	return ret;
 
 error_undo:
-	if (device->writeable) {
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 		mutex_lock(&fs_info->chunk_mutex);
 		list_add(&device->dev_alloc_list,
 			 &fs_info->fs_devices->alloc_list);
@@ -2003,10 +2059,10 @@ void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_fs_info *fs_info,
 	list_del_rcu(&srcdev->dev_list);
 	list_del(&srcdev->dev_alloc_list);
 	fs_devices->num_devices--;
-	if (srcdev->missing)
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &srcdev->dev_state))
 		fs_devices->missing_devices--;
 
-	if (srcdev->writeable)
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &srcdev->dev_state))
 		fs_devices->rw_devices--;
 
 	if (srcdev->bdev)
@@ -2018,13 +2074,13 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_fs_devices *fs_devices = srcdev->fs_devices;
 
-	if (srcdev->writeable) {
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &srcdev->dev_state)) {
 		/* zero out the old super if it is writable */
 		btrfs_scratch_superblocks(srcdev->bdev, srcdev->name->str);
 	}
 
 	btrfs_close_bdev(srcdev);
-	call_rcu(&srcdev->rcu, free_device);
+	call_rcu(&srcdev->rcu, free_device_rcu);
 
 	/* if this is no devs we rather delete the fs_devices */
 	if (!fs_devices->num_devices) {
@@ -2083,7 +2139,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	btrfs_scratch_superblocks(tgtdev->bdev, tgtdev->name->str);
 
 	btrfs_close_bdev(tgtdev);
-	call_rcu(&tgtdev->rcu, free_device);
+	call_rcu(&tgtdev->rcu, free_device_rcu);
 }
 
 static int btrfs_find_device_by_path(struct btrfs_fs_info *fs_info,
@@ -2128,7 +2184,8 @@ int btrfs_find_device_missing_or_by_path(struct btrfs_fs_info *fs_info,
 		 * is held by the caller.
 		 */
 		list_for_each_entry(tmp, devices, dev_list) {
-			if (tmp->in_fs_metadata && !tmp->bdev) {
+			if (test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+					&tmp->dev_state) && !tmp->bdev) {
 				*device = tmp;
 				break;
 			}
@@ -2357,26 +2414,19 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 
 	name = rcu_string_strdup(device_path, GFP_KERNEL);
 	if (!name) {
-		bio_put(device->flush_bio);
-		kfree(device);
 		ret = -ENOMEM;
-		goto error;
+		goto error_free_device;
 	}
 	rcu_assign_pointer(device->name, name);
 
 	trans = btrfs_start_transaction(root, 0);
 	if (IS_ERR(trans)) {
-		rcu_string_free(device->name);
-		bio_put(device->flush_bio);
-		kfree(device);
 		ret = PTR_ERR(trans);
-		goto error;
+		goto error_free_device;
 	}
 
 	q = bdev_get_queue(bdev);
-	if (blk_queue_discard(q))
-		device->can_discard = 1;
-	device->writeable = 1;
+	set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 	device->generation = trans->transid;
 	device->io_width = fs_info->sectorsize;
 	device->io_align = fs_info->sectorsize;
@@ -2387,8 +2437,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 	device->commit_total_bytes = device->total_bytes;
 	device->fs_info = fs_info;
 	device->bdev = bdev;
-	device->in_fs_metadata = 1;
-	device->is_tgtdev_for_dev_replace = 0;
+	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
+	clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 	device->mode = FMODE_EXCL;
 	device->dev_stats_valid = 1;
 	set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
@@ -2449,7 +2499,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 		}
 	}
 
-	ret = btrfs_add_device(trans, fs_info, device);
+	ret = btrfs_add_dev_item(trans, fs_info, device);
 	if (ret) {
 		btrfs_abort_transaction(trans, ret);
 		goto error_sysfs;
@@ -2510,9 +2560,8 @@ error_trans:
 		sb->s_flags |= SB_RDONLY;
 	if (trans)
 		btrfs_end_transaction(trans);
-	rcu_string_free(device->name);
-	bio_put(device->flush_bio);
-	kfree(device);
+error_free_device:
+	free_device(device);
 error:
 	blkdev_put(bdev, FMODE_EXCL);
 	if (seeding_dev && !unlocked) {
@@ -2527,7 +2576,6 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 				  struct btrfs_device *srcdev,
 				  struct btrfs_device **device_out)
 {
-	struct request_queue *q;
 	struct btrfs_device *device;
 	struct block_device *bdev;
 	struct list_head *devices;
@@ -2578,18 +2626,14 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 
 	name = rcu_string_strdup(device_path, GFP_KERNEL);
 	if (!name) {
-		bio_put(device->flush_bio);
-		kfree(device);
+		free_device(device);
 		ret = -ENOMEM;
 		goto error;
 	}
 	rcu_assign_pointer(device->name, name);
 
-	q = bdev_get_queue(bdev);
-	if (blk_queue_discard(q))
-		device->can_discard = 1;
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
-	device->writeable = 1;
+	set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
 	device->generation = 0;
 	device->io_width = fs_info->sectorsize;
 	device->io_align = fs_info->sectorsize;
@@ -2602,8 +2646,8 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	device->commit_bytes_used = device->bytes_used;
 	device->fs_info = fs_info;
 	device->bdev = bdev;
-	device->in_fs_metadata = 1;
-	device->is_tgtdev_for_dev_replace = 1;
+	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
+	set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 	device->mode = FMODE_EXCL;
 	device->dev_stats_valid = 1;
 	set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
@@ -2631,7 +2675,7 @@ void btrfs_init_dev_replace_tgtdev_for_resume(struct btrfs_fs_info *fs_info,
 	tgtdev->io_align = sectorsize;
 	tgtdev->sector_size = sectorsize;
 	tgtdev->fs_info = fs_info;
-	tgtdev->in_fs_metadata = 1;
+	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &tgtdev->dev_state);
 }
 
 static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
@@ -2689,7 +2733,7 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 	u64 old_total;
 	u64 diff;
 
-	if (!device->writeable)
+	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
 		return -EACCES;
 
 	new_size = round_down(new_size, fs_info->sectorsize);
@@ -2699,7 +2743,7 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 	diff = round_down(new_size - device->total_bytes, fs_info->sectorsize);
 
 	if (new_size <= device->total_bytes ||
-	    device->is_tgtdev_for_dev_replace) {
+	    test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
 		mutex_unlock(&fs_info->chunk_mutex);
 		return -EINVAL;
 	}
@@ -3043,6 +3087,48 @@ error:
 	return ret;
 }
 
+/*
+ * return 1 : allocate a data chunk successfully,
+ * return <0: errors during allocating a data chunk,
+ * return 0 : no need to allocate a data chunk.
+ */
+static int btrfs_may_alloc_data_chunk(struct btrfs_fs_info *fs_info,
+				      u64 chunk_offset)
+{
+	struct btrfs_block_group_cache *cache;
+	u64 bytes_used;
+	u64 chunk_type;
+
+	cache = btrfs_lookup_block_group(fs_info, chunk_offset);
+	ASSERT(cache);
+	chunk_type = cache->flags;
+	btrfs_put_block_group(cache);
+
+	if (chunk_type & BTRFS_BLOCK_GROUP_DATA) {
+		spin_lock(&fs_info->data_sinfo->lock);
+		bytes_used = fs_info->data_sinfo->bytes_used;
+		spin_unlock(&fs_info->data_sinfo->lock);
+
+		if (!bytes_used) {
+			struct btrfs_trans_handle *trans;
+			int ret;
+
+			trans =	btrfs_join_transaction(fs_info->tree_root);
+			if (IS_ERR(trans))
+				return PTR_ERR(trans);
+
+			ret = btrfs_force_chunk_alloc(trans, fs_info,
+						      BTRFS_BLOCK_GROUP_DATA);
+			btrfs_end_transaction(trans);
+			if (ret < 0)
+				return ret;
+
+			return 1;
+		}
+	}
+	return 0;
+}
+
 static int insert_balance_item(struct btrfs_fs_info *fs_info,
 			       struct btrfs_balance_control *bctl)
 {
@@ -3501,7 +3587,6 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 	u32 count_meta = 0;
 	u32 count_sys = 0;
 	int chunk_reserved = 0;
-	u64 bytes_used = 0;
 
 	/* step one make some room on all the devices */
 	devices = &fs_info->fs_devices->devices;
@@ -3509,10 +3594,10 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 		old_size = btrfs_device_get_total_bytes(device);
 		size_to_free = div_factor(old_size, 1);
 		size_to_free = min_t(u64, size_to_free, SZ_1M);
-		if (!device->writeable ||
+		if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) ||
 		    btrfs_device_get_total_bytes(device) -
 		    btrfs_device_get_bytes_used(device) > size_to_free ||
-		    device->is_tgtdev_for_dev_replace)
+		    test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
 			continue;
 
 		ret = btrfs_shrink_device(device, old_size - size_to_free);
@@ -3660,28 +3745,21 @@ again:
 			goto loop;
 		}
 
-		ASSERT(fs_info->data_sinfo);
-		spin_lock(&fs_info->data_sinfo->lock);
-		bytes_used = fs_info->data_sinfo->bytes_used;
-		spin_unlock(&fs_info->data_sinfo->lock);
-
-		if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) &&
-		    !chunk_reserved && !bytes_used) {
-			trans = btrfs_start_transaction(chunk_root, 0);
-			if (IS_ERR(trans)) {
-				mutex_unlock(&fs_info->delete_unused_bgs_mutex);
-				ret = PTR_ERR(trans);
-				goto error;
-			}
-
-			ret = btrfs_force_chunk_alloc(trans, fs_info,
-						      BTRFS_BLOCK_GROUP_DATA);
-			btrfs_end_transaction(trans);
+		if (!chunk_reserved) {
+			/*
+			 * We may be relocating the only data chunk we have,
+			 * which could potentially end up with losing data's
+			 * raid profile, so lets allocate an empty one in
+			 * advance.
+			 */
+			ret = btrfs_may_alloc_data_chunk(fs_info,
+							 found_key.offset);
 			if (ret < 0) {
 				mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 				goto error;
+			} else if (ret == 1) {
+				chunk_reserved = 1;
 			}
-			chunk_reserved = 1;
 		}
 
 		ret = btrfs_relocate_chunk(fs_info, found_key.offset);
@@ -4380,7 +4458,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 	new_size = round_down(new_size, fs_info->sectorsize);
 	diff = round_down(old_size - new_size, fs_info->sectorsize);
 
-	if (device->is_tgtdev_for_dev_replace)
+	if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
 		return -EINVAL;
 
 	path = btrfs_alloc_path();
@@ -4392,7 +4470,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 	mutex_lock(&fs_info->chunk_mutex);
 
 	btrfs_device_set_total_bytes(device, new_size);
-	if (device->writeable) {
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 		device->fs_devices->total_rw_bytes -= diff;
 		atomic64_sub(diff, &fs_info->free_chunk_space);
 	}
@@ -4444,6 +4522,18 @@ again:
 		chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
 		btrfs_release_path(path);
 
+		/*
+		 * We may be relocating the only data chunk we have,
+		 * which could potentially end up with losing data's
+		 * raid profile, so lets allocate an empty one in
+		 * advance.
+		 */
+		ret = btrfs_may_alloc_data_chunk(fs_info, chunk_offset);
+		if (ret < 0) {
+			mutex_unlock(&fs_info->delete_unused_bgs_mutex);
+			goto done;
+		}
+
 		ret = btrfs_relocate_chunk(fs_info, chunk_offset);
 		mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 		if (ret && ret != -ENOSPC)
@@ -4517,7 +4607,7 @@ done:
 	if (ret) {
 		mutex_lock(&fs_info->chunk_mutex);
 		btrfs_device_set_total_bytes(device, old_size);
-		if (device->writeable)
+		if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
 			device->fs_devices->total_rw_bytes += diff;
 		atomic64_add(diff, &fs_info->free_chunk_space);
 		mutex_unlock(&fs_info->chunk_mutex);
@@ -4677,14 +4767,15 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		u64 max_avail;
 		u64 dev_offset;
 
-		if (!device->writeable) {
+		if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
 			WARN(1, KERN_ERR
 			       "BTRFS: read-only device in alloc_list\n");
 			continue;
 		}
 
-		if (!device->in_fs_metadata ||
-		    device->is_tgtdev_for_dev_replace)
+		if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+					&device->dev_state) ||
+		    test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
 			continue;
 
 		if (device->total_bytes > device->bytes_used)
@@ -5032,12 +5123,13 @@ int btrfs_chunk_readonly(struct btrfs_fs_info *fs_info, u64 chunk_offset)
 
 	map = em->map_lookup;
 	for (i = 0; i < map->num_stripes; i++) {
-		if (map->stripes[i].dev->missing) {
+		if (test_bit(BTRFS_DEV_STATE_MISSING,
+					&map->stripes[i].dev->dev_state)) {
 			miss_ndevs++;
 			continue;
 		}
-
-		if (!map->stripes[i].dev->writeable) {
+		if (!test_bit(BTRFS_DEV_STATE_WRITEABLE,
+					&map->stripes[i].dev->dev_state)) {
 			readonly = 1;
 			goto end;
 		}
@@ -5103,7 +5195,14 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
 	else if (map->type & BTRFS_BLOCK_GROUP_RAID5)
 		ret = 2;
 	else if (map->type & BTRFS_BLOCK_GROUP_RAID6)
-		ret = 3;
+		/*
+		 * There could be two corrupted data stripes, we need
+		 * to loop retry in order to rebuild the correct data.
+		 * 
+		 * Fail a stripe at a time on every retry except the
+		 * stripe under reconstruction.
+		 */
+		ret = map->num_stripes;
 	else
 		ret = 1;
 	free_extent_map(em);
@@ -6003,15 +6102,14 @@ static void btrfs_end_bio(struct bio *bio)
 			dev = bbio->stripes[stripe_index].dev;
 			if (dev->bdev) {
 				if (bio_op(bio) == REQ_OP_WRITE)
-					btrfs_dev_stat_inc(dev,
+					btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_WRITE_ERRS);
 				else
-					btrfs_dev_stat_inc(dev,
+					btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_READ_ERRS);
 				if (bio->bi_opf & REQ_PREFLUSH)
-					btrfs_dev_stat_inc(dev,
+					btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_FLUSH_ERRS);
-				btrfs_dev_stat_print_on_error(dev);
 			}
 		}
 	}
@@ -6061,16 +6159,15 @@ static noinline void btrfs_schedule_bio(struct btrfs_device *device,
 	int should_queue = 1;
 	struct btrfs_pending_bios *pending_bios;
 
-	if (device->missing || !device->bdev) {
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state) ||
+	    !device->bdev) {
 		bio_io_error(bio);
 		return;
 	}
 
 	/* don't bother with additional async steps for reads, right now */
 	if (bio_op(bio) == REQ_OP_READ) {
-		bio_get(bio);
 		btrfsic_submit_bio(bio);
-		bio_put(bio);
 		return;
 	}
 
@@ -6207,7 +6304,8 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 	for (dev_nr = 0; dev_nr < total_devs; dev_nr++) {
 		dev = bbio->stripes[dev_nr].dev;
 		if (!dev || !dev->bdev ||
-		    (bio_op(first_bio) == REQ_OP_WRITE && !dev->writeable)) {
+		    (bio_op(first_bio) == REQ_OP_WRITE &&
+		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))) {
 			bbio_error(bbio, first_bio, logical);
 			continue;
 		}
@@ -6256,7 +6354,7 @@ static struct btrfs_device *add_missing_dev(struct btrfs_fs_devices *fs_devices,
 	device->fs_devices = fs_devices;
 	fs_devices->num_devices++;
 
-	device->missing = 1;
+	set_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);
 	fs_devices->missing_devices++;
 
 	return device;
@@ -6272,8 +6370,8 @@ static struct btrfs_device *add_missing_dev(struct btrfs_fs_devices *fs_devices,
  *		is generated.
  *
  * Return: a pointer to a new &struct btrfs_device on success; ERR_PTR()
- * on error.  Returned struct is not linked onto any lists and can be
- * destroyed with kfree() right away.
+ * on error.  Returned struct is not linked onto any lists and must be
+ * destroyed with free_device.
  */
 struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 					const u64 *devid,
@@ -6296,8 +6394,7 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 
 		ret = find_next_devid(fs_info, &tmp);
 		if (ret) {
-			bio_put(dev->flush_bio);
-			kfree(dev);
+			free_device(dev);
 			return ERR_PTR(ret);
 		}
 	}
@@ -6476,7 +6573,9 @@ static int read_one_chunk(struct btrfs_fs_info *fs_info, struct btrfs_key *key,
 			}
 			btrfs_report_missing_device(fs_info, devid, uuid, false);
 		}
-		map->stripes[i].dev->in_fs_metadata = 1;
+		set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+				&(map->stripes[i].dev->dev_state));
+
 	}
 
 	write_lock(&map_tree->map_tree.lock);
@@ -6505,7 +6604,7 @@ static void fill_device_from_item(struct extent_buffer *leaf,
 	device->io_width = btrfs_device_io_width(leaf, dev_item);
 	device->sector_size = btrfs_device_sector_size(leaf, dev_item);
 	WARN_ON(device->devid == BTRFS_DEV_REPLACE_DEVID);
-	device->is_tgtdev_for_dev_replace = 0;
+	clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 
 	ptr = btrfs_device_uuid(dev_item);
 	read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
@@ -6617,7 +6716,8 @@ static int read_one_dev(struct btrfs_fs_info *fs_info,
 							dev_uuid, false);
 		}
 
-		if(!device->bdev && !device->missing) {
+		if (!device->bdev &&
+		    !test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
 			/*
 			 * this happens when a device that was properly setup
 			 * in the device info lists suddenly goes bad.
@@ -6625,12 +6725,13 @@ static int read_one_dev(struct btrfs_fs_info *fs_info,
 			 * device->missing to one here
 			 */
 			device->fs_devices->missing_devices++;
-			device->missing = 1;
+			set_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);
 		}
 
 		/* Move the device to its own fs_devices */
 		if (device->fs_devices != fs_devices) {
-			ASSERT(device->missing);
+			ASSERT(test_bit(BTRFS_DEV_STATE_MISSING,
+							&device->dev_state));
 
 			list_move(&device->dev_list, &fs_devices->devices);
 			device->fs_devices->num_devices--;
@@ -6644,15 +6745,16 @@ static int read_one_dev(struct btrfs_fs_info *fs_info,
 	}
 
 	if (device->fs_devices != fs_info->fs_devices) {
-		BUG_ON(device->writeable);
+		BUG_ON(test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state));
 		if (device->generation !=
 		    btrfs_device_generation(leaf, dev_item))
 			return -EINVAL;
 	}
 
 	fill_device_from_item(leaf, dev_item, device);
-	device->in_fs_metadata = 1;
-	if (device->writeable && !device->is_tgtdev_for_dev_replace) {
+	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
+	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
+	   !test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
 		device->fs_devices->total_rw_bytes += device->total_bytes;
 		atomic64_add(device->total_bytes - device->bytes_used,
 				&fs_info->free_chunk_space);
@@ -6784,10 +6886,13 @@ out_short_read:
 /*
  * Check if all chunks in the fs are OK for read-write degraded mount
  *
+ * If the @failing_dev is specified, it's accounted as missing.
+ *
  * Return true if all chunks meet the minimal RW mount requirements.
  * Return false if any chunk doesn't meet the minimal RW mount requirements.
  */
-bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info)
+bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info,
+					struct btrfs_device *failing_dev)
 {
 	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
 	struct extent_map *em;
@@ -6815,12 +6920,16 @@ bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info)
 		for (i = 0; i < map->num_stripes; i++) {
 			struct btrfs_device *dev = map->stripes[i].dev;
 
-			if (!dev || !dev->bdev || dev->missing ||
+			if (!dev || !dev->bdev ||
+			    test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) ||
 			    dev->last_flush_error)
 				missing++;
+			else if (failing_dev && failing_dev == dev)
+				missing++;
 		}
 		if (missing > max_tolerated) {
-			btrfs_warn(fs_info,
+			if (!failing_dev)
+				btrfs_warn(fs_info,
 	"chunk %llu missing %d devices, max tolerance is %d for writeable mount",
 				   em->start, missing, max_tolerated);
 			free_extent_map(em);
@@ -7091,10 +7200,24 @@ int btrfs_run_dev_stats(struct btrfs_trans_handle *trans,
 
 	mutex_lock(&fs_devices->device_list_mutex);
 	list_for_each_entry(device, &fs_devices->devices, dev_list) {
-		if (!device->dev_stats_valid || !btrfs_dev_stats_dirty(device))
+		stats_cnt = atomic_read(&device->dev_stats_ccnt);
+		if (!device->dev_stats_valid || stats_cnt == 0)
 			continue;
 
-		stats_cnt = atomic_read(&device->dev_stats_ccnt);
+
+		/*
+		 * There is a LOAD-LOAD control dependency between the value of
+		 * dev_stats_ccnt and updating the on-disk values which requires
+		 * reading the in-memory counters. Such control dependencies
+		 * require explicit read memory barriers.
+		 *
+		 * This memory barriers pairs with smp_mb__before_atomic in
+		 * btrfs_dev_stat_inc/btrfs_dev_stat_set and with the full
+		 * barrier implied by atomic_xchg in
+		 * btrfs_dev_stats_read_and_reset
+		 */
+		smp_rmb();
+
 		ret = update_dev_stat_item(trans, fs_info, device);
 		if (!ret)
 			atomic_sub(stats_cnt, &device->dev_stats_ccnt);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index ff15208344a7..28c28eeadff3 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -47,6 +47,12 @@ struct btrfs_pending_bios {
 #define btrfs_device_data_ordered_init(device) do { } while (0)
 #endif
 
+#define BTRFS_DEV_STATE_WRITEABLE	(0)
+#define BTRFS_DEV_STATE_IN_FS_METADATA	(1)
+#define BTRFS_DEV_STATE_MISSING		(2)
+#define BTRFS_DEV_STATE_REPLACE_TGT	(3)
+#define BTRFS_DEV_STATE_FLUSH_SENT	(4)
+
 struct btrfs_device {
 	struct list_head dev_list;
 	struct list_head dev_alloc_list;
@@ -69,11 +75,7 @@ struct btrfs_device {
 	/* the mode sent to blkdev_get */
 	fmode_t mode;
 
-	int writeable;
-	int in_fs_metadata;
-	int missing;
-	int can_discard;
-	int is_tgtdev_for_dev_replace;
+	unsigned long dev_state;
 	blk_status_t last_flush_error;
 	int flush_bio_sent;
 
@@ -129,14 +131,12 @@ struct btrfs_device {
 	struct completion flush_wait;
 
 	/* per-device scrub information */
-	struct scrub_ctx *scrub_device;
+	struct scrub_ctx *scrub_ctx;
 
 	struct btrfs_work work;
 	struct rcu_head rcu;
-	struct work_struct rcu_work;
 
 	/* readahead state */
-	spinlock_t reada_lock;
 	atomic_t reada_in_flight;
 	u64 reada_next;
 	struct reada_zone *reada_curr_zone;
@@ -489,15 +489,16 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
 int btrfs_remove_chunk(struct btrfs_trans_handle *trans,
 		       struct btrfs_fs_info *fs_info, u64 chunk_offset);
 
-static inline int btrfs_dev_stats_dirty(struct btrfs_device *dev)
-{
-	return atomic_read(&dev->dev_stats_ccnt);
-}
-
 static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
 				      int index)
 {
 	atomic_inc(dev->dev_stat_values + index);
+	/*
+	 * This memory barrier orders stores updating statistics before stores
+	 * updating dev_stats_ccnt.
+	 *
+	 * It pairs with smp_rmb() in btrfs_run_dev_stats().
+	 */
 	smp_mb__before_atomic();
 	atomic_inc(&dev->dev_stats_ccnt);
 }
@@ -514,7 +515,13 @@ static inline int btrfs_dev_stat_read_and_reset(struct btrfs_device *dev,
 	int ret;
 
 	ret = atomic_xchg(dev->dev_stat_values + index, 0);
-	smp_mb__before_atomic();
+	/*
+	 * atomic_xchg implies a full memory barriers as per atomic_t.txt:
+	 * - RMW operations that have a return value are fully ordered;
+	 *
+	 * This implicit memory barriers is paired with the smp_rmb in
+	 * btrfs_run_dev_stats
+	 */
 	atomic_inc(&dev->dev_stats_ccnt);
 	return ret;
 }
@@ -523,6 +530,12 @@ static inline void btrfs_dev_stat_set(struct btrfs_device *dev,
 				      int index, unsigned long val)
 {
 	atomic_set(dev->dev_stat_values + index, val);
+	/*
+	 * This memory barrier orders stores updating statistics before stores
+	 * updating dev_stats_ccnt.
+	 *
+	 * It pairs with smp_rmb() in btrfs_run_dev_stats().
+	 */
 	smp_mb__before_atomic();
 	atomic_inc(&dev->dev_stats_ccnt);
 }
@@ -540,7 +553,7 @@ void btrfs_update_commit_device_bytes_used(struct btrfs_fs_info *fs_info,
 struct list_head *btrfs_get_fs_uuids(void);
 void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info);
 void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info);
-
-bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info);
+bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info,
+					struct btrfs_device *failing_dev);
 
 #endif
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 5258c1714830..de7d072c78ef 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -268,7 +268,6 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 {
 	struct btrfs_key key;
 	struct inode *inode = d_inode(dentry);
-	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_path *path;
 	int ret = 0;
@@ -337,11 +336,6 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 			u32 this_len = sizeof(*di) + name_len + data_len;
 			unsigned long name_ptr = (unsigned long)(di + 1);
 
-			if (verify_dir_item(fs_info, leaf, slot, di)) {
-				ret = -EIO;
-				goto err;
-			}
-
 			total_size += name_len + 1;
 			/*
 			 * We are just looking for how big our buffer needs to
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 17f2dd8fddb8..01a4eab602a3 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -43,6 +43,8 @@ struct workspace {
 	size_t size;
 	char *buf;
 	struct list_head list;
+	ZSTD_inBuffer in_buf;
+	ZSTD_outBuffer out_buf;
 };
 
 static void zstd_free_workspace(struct list_head *ws)
@@ -94,8 +96,6 @@ static int zstd_compress_pages(struct list_head *ws,
 	int nr_pages = 0;
 	struct page *in_page = NULL;  /* The current page to read */
 	struct page *out_page = NULL; /* The current page to write to */
-	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
-	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
 	unsigned long tot_in = 0;
 	unsigned long tot_out = 0;
 	unsigned long len = *total_out;
@@ -118,9 +118,9 @@ static int zstd_compress_pages(struct list_head *ws,
 
 	/* map in the first page of input data */
 	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-	in_buf.src = kmap(in_page);
-	in_buf.pos = 0;
-	in_buf.size = min_t(size_t, len, PAGE_SIZE);
+	workspace->in_buf.src = kmap(in_page);
+	workspace->in_buf.pos = 0;
+	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 
 
 	/* Allocate and map in the output buffer */
@@ -130,14 +130,15 @@ static int zstd_compress_pages(struct list_head *ws,
 		goto out;
 	}
 	pages[nr_pages++] = out_page;
-	out_buf.dst = kmap(out_page);
-	out_buf.pos = 0;
-	out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
+	workspace->out_buf.dst = kmap(out_page);
+	workspace->out_buf.pos = 0;
+	workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 
 	while (1) {
 		size_t ret2;
 
-		ret2 = ZSTD_compressStream(stream, &out_buf, &in_buf);
+		ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
+				&workspace->in_buf);
 		if (ZSTD_isError(ret2)) {
 			pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
 					ZSTD_getErrorCode(ret2));
@@ -146,22 +147,22 @@ static int zstd_compress_pages(struct list_head *ws,
 		}
 
 		/* Check to see if we are making it bigger */
-		if (tot_in + in_buf.pos > 8192 &&
-				tot_in + in_buf.pos <
-				tot_out + out_buf.pos) {
+		if (tot_in + workspace->in_buf.pos > 8192 &&
+				tot_in + workspace->in_buf.pos <
+				tot_out + workspace->out_buf.pos) {
 			ret = -E2BIG;
 			goto out;
 		}
 
 		/* We've reached the end of our output range */
-		if (out_buf.pos >= max_out) {
-			tot_out += out_buf.pos;
+		if (workspace->out_buf.pos >= max_out) {
+			tot_out += workspace->out_buf.pos;
 			ret = -E2BIG;
 			goto out;
 		}
 
 		/* Check if we need more output space */
-		if (out_buf.pos == out_buf.size) {
+		if (workspace->out_buf.pos == workspace->out_buf.size) {
 			tot_out += PAGE_SIZE;
 			max_out -= PAGE_SIZE;
 			kunmap(out_page);
@@ -176,19 +177,20 @@ static int zstd_compress_pages(struct list_head *ws,
 				goto out;
 			}
 			pages[nr_pages++] = out_page;
-			out_buf.dst = kmap(out_page);
-			out_buf.pos = 0;
-			out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
+			workspace->out_buf.dst = kmap(out_page);
+			workspace->out_buf.pos = 0;
+			workspace->out_buf.size = min_t(size_t, max_out,
+							PAGE_SIZE);
 		}
 
 		/* We've reached the end of the input */
-		if (in_buf.pos >= len) {
-			tot_in += in_buf.pos;
+		if (workspace->in_buf.pos >= len) {
+			tot_in += workspace->in_buf.pos;
 			break;
 		}
 
 		/* Check if we need more input */
-		if (in_buf.pos == in_buf.size) {
+		if (workspace->in_buf.pos == workspace->in_buf.size) {
 			tot_in += PAGE_SIZE;
 			kunmap(in_page);
 			put_page(in_page);
@@ -196,15 +198,15 @@ static int zstd_compress_pages(struct list_head *ws,
 			start += PAGE_SIZE;
 			len -= PAGE_SIZE;
 			in_page = find_get_page(mapping, start >> PAGE_SHIFT);
-			in_buf.src = kmap(in_page);
-			in_buf.pos = 0;
-			in_buf.size = min_t(size_t, len, PAGE_SIZE);
+			workspace->in_buf.src = kmap(in_page);
+			workspace->in_buf.pos = 0;
+			workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
 		}
 	}
 	while (1) {
 		size_t ret2;
 
-		ret2 = ZSTD_endStream(stream, &out_buf);
+		ret2 = ZSTD_endStream(stream, &workspace->out_buf);
 		if (ZSTD_isError(ret2)) {
 			pr_debug("BTRFS: ZSTD_endStream returned %d\n",
 					ZSTD_getErrorCode(ret2));
@@ -212,11 +214,11 @@ static int zstd_compress_pages(struct list_head *ws,
 			goto out;
 		}
 		if (ret2 == 0) {
-			tot_out += out_buf.pos;
+			tot_out += workspace->out_buf.pos;
 			break;
 		}
-		if (out_buf.pos >= max_out) {
-			tot_out += out_buf.pos;
+		if (workspace->out_buf.pos >= max_out) {
+			tot_out += workspace->out_buf.pos;
 			ret = -E2BIG;
 			goto out;
 		}
@@ -235,9 +237,9 @@ static int zstd_compress_pages(struct list_head *ws,
 			goto out;
 		}
 		pages[nr_pages++] = out_page;
-		out_buf.dst = kmap(out_page);
-		out_buf.pos = 0;
-		out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
+		workspace->out_buf.dst = kmap(out_page);
+		workspace->out_buf.pos = 0;
+		workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
 	}
 
 	if (tot_out >= tot_in) {
@@ -273,8 +275,6 @@ static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
 	unsigned long buf_start;
 	unsigned long total_out = 0;
-	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
-	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
 
 	stream = ZSTD_initDStream(
 			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
@@ -284,18 +284,19 @@ static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 		goto done;
 	}
 
-	in_buf.src = kmap(pages_in[page_in_index]);
-	in_buf.pos = 0;
-	in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
+	workspace->in_buf.src = kmap(pages_in[page_in_index]);
+	workspace->in_buf.pos = 0;
+	workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 
-	out_buf.dst = workspace->buf;
-	out_buf.pos = 0;
-	out_buf.size = PAGE_SIZE;
+	workspace->out_buf.dst = workspace->buf;
+	workspace->out_buf.pos = 0;
+	workspace->out_buf.size = PAGE_SIZE;
 
 	while (1) {
 		size_t ret2;
 
-		ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
+		ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
+				&workspace->in_buf);
 		if (ZSTD_isError(ret2)) {
 			pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 					ZSTD_getErrorCode(ret2));
@@ -303,38 +304,38 @@ static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
 			goto done;
 		}
 		buf_start = total_out;
-		total_out += out_buf.pos;
-		out_buf.pos = 0;
+		total_out += workspace->out_buf.pos;
+		workspace->out_buf.pos = 0;
 
-		ret = btrfs_decompress_buf2page(out_buf.dst, buf_start,
-				total_out, disk_start, orig_bio);
+		ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
+				buf_start, total_out, disk_start, orig_bio);
 		if (ret == 0)
 			break;
 
-		if (in_buf.pos >= srclen)
+		if (workspace->in_buf.pos >= srclen)
 			break;
 
 		/* Check if we've hit the end of a frame */
 		if (ret2 == 0)
 			break;
 
-		if (in_buf.pos == in_buf.size) {
+		if (workspace->in_buf.pos == workspace->in_buf.size) {
 			kunmap(pages_in[page_in_index++]);
 			if (page_in_index >= total_pages_in) {
-				in_buf.src = NULL;
+				workspace->in_buf.src = NULL;
 				ret = -EIO;
 				goto done;
 			}
 			srclen -= PAGE_SIZE;
-			in_buf.src = kmap(pages_in[page_in_index]);
-			in_buf.pos = 0;
-			in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
+			workspace->in_buf.src = kmap(pages_in[page_in_index]);
+			workspace->in_buf.pos = 0;
+			workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
 		}
 	}
 	ret = 0;
 	zero_fill_bio(orig_bio);
 done:
-	if (in_buf.src)
+	if (workspace->in_buf.src)
 		kunmap(pages_in[page_in_index]);
 	return ret;
 }
@@ -348,8 +349,6 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 	ZSTD_DStream *stream;
 	int ret = 0;
 	size_t ret2;
-	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
-	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
 	unsigned long total_out = 0;
 	unsigned long pg_offset = 0;
 	char *kaddr;
@@ -364,16 +363,17 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 
 	destlen = min_t(size_t, destlen, PAGE_SIZE);
 
-	in_buf.src = data_in;
-	in_buf.pos = 0;
-	in_buf.size = srclen;
+	workspace->in_buf.src = data_in;
+	workspace->in_buf.pos = 0;
+	workspace->in_buf.size = srclen;
 
-	out_buf.dst = workspace->buf;
-	out_buf.pos = 0;
-	out_buf.size = PAGE_SIZE;
+	workspace->out_buf.dst = workspace->buf;
+	workspace->out_buf.pos = 0;
+	workspace->out_buf.size = PAGE_SIZE;
 
 	ret2 = 1;
-	while (pg_offset < destlen && in_buf.pos < in_buf.size) {
+	while (pg_offset < destlen
+	       && workspace->in_buf.pos < workspace->in_buf.size) {
 		unsigned long buf_start;
 		unsigned long buf_offset;
 		unsigned long bytes;
@@ -384,7 +384,8 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 			ret = -EIO;
 			goto finish;
 		}
-		ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
+		ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
+				&workspace->in_buf);
 		if (ZSTD_isError(ret2)) {
 			pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
 					ZSTD_getErrorCode(ret2));
@@ -393,8 +394,8 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 		}
 
 		buf_start = total_out;
-		total_out += out_buf.pos;
-		out_buf.pos = 0;
+		total_out += workspace->out_buf.pos;
+		workspace->out_buf.pos = 0;
 
 		if (total_out <= start_byte)
 			continue;
@@ -405,10 +406,11 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 			buf_offset = 0;
 
 		bytes = min_t(unsigned long, destlen - pg_offset,
-				out_buf.size - buf_offset);
+				workspace->out_buf.size - buf_offset);
 
 		kaddr = kmap_atomic(dest_page);
-		memcpy(kaddr + pg_offset, out_buf.dst + buf_offset, bytes);
+		memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
+				bytes);
 		kunmap_atomic(kaddr);
 
 		pg_offset += bytes;