aboutsummaryrefslogtreecommitdiff
path: root/fs/btrfs
diff options
context:
space:
mode:
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/block-group.c9
-rw-r--r--fs/btrfs/ctree.c98
-rw-r--r--fs/btrfs/ctree.h14
-rw-r--r--fs/btrfs/disk-io.c4
-rw-r--r--fs/btrfs/relocation.c13
-rw-r--r--fs/btrfs/send.c357
-rw-r--r--fs/btrfs/transaction.c4
7 files changed, 395 insertions, 104 deletions
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 7d6372103aaf..1db24e6d6d90 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1509,7 +1509,6 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
container_of(work, struct btrfs_fs_info, reclaim_bgs_work);
struct btrfs_block_group *bg;
struct btrfs_space_info *space_info;
- LIST_HEAD(again_list);
if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
return;
@@ -1586,18 +1585,14 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
div64_u64(zone_unusable * 100, bg->length));
trace_btrfs_reclaim_block_group(bg);
ret = btrfs_relocate_chunk(fs_info, bg->start);
- if (ret && ret != -EAGAIN)
+ if (ret)
btrfs_err(fs_info, "error relocating chunk %llu",
bg->start);
next:
+ btrfs_put_block_group(bg);
spin_lock(&fs_info->unused_bgs_lock);
- if (ret == -EAGAIN && list_empty(&bg->bg_list))
- list_add_tail(&bg->bg_list, &again_list);
- else
- btrfs_put_block_group(bg);
}
- list_splice_tail(&again_list, &fs_info->reclaim_bgs);
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
btrfs_exclop_finish(fs_info);
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 94b2be118b50..9e02ac51c664 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1568,7 +1568,6 @@ static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
struct btrfs_path *p,
int write_lock_level)
{
- struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *b;
int root_lock;
int level = 0;
@@ -1577,26 +1576,8 @@ static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
root_lock = BTRFS_READ_LOCK;
if (p->search_commit_root) {
- /*
- * The commit roots are read only so we always do read locks,
- * and we always must hold the commit_root_sem when doing
- * searches on them, the only exception is send where we don't
- * want to block transaction commits for a long time, so
- * we need to clone the commit root in order to avoid races
- * with transaction commits that create a snapshot of one of
- * the roots used by a send operation.
- */
- if (p->need_commit_sem) {
- down_read(&fs_info->commit_root_sem);
- b = btrfs_clone_extent_buffer(root->commit_root);
- up_read(&fs_info->commit_root_sem);
- if (!b)
- return ERR_PTR(-ENOMEM);
-
- } else {
- b = root->commit_root;
- atomic_inc(&b->refs);
- }
+ b = root->commit_root;
+ atomic_inc(&b->refs);
level = btrfs_header_level(b);
/*
* Ensure that all callers have set skip_locking when
@@ -1648,6 +1629,42 @@ out:
return b;
}
+/*
+ * Replace the extent buffer at the lowest level of the path with a cloned
+ * version. The purpose is to be able to use it safely, after releasing the
+ * commit root semaphore, even if relocation is happening in parallel, the
+ * transaction used for relocation is committed and the extent buffer is
+ * reallocated in the next transaction.
+ *
+ * This is used in a context where the caller does not prevent transaction
+ * commits from happening, either by holding a transaction handle or holding
+ * some lock, while it's doing searches through a commit root.
+ * At the moment it's only used for send operations.
+ */
+static int finish_need_commit_sem_search(struct btrfs_path *path)
+{
+ const int i = path->lowest_level;
+ const int slot = path->slots[i];
+ struct extent_buffer *lowest = path->nodes[i];
+ struct extent_buffer *clone;
+
+ ASSERT(path->need_commit_sem);
+
+ if (!lowest)
+ return 0;
+
+ lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
+
+ clone = btrfs_clone_extent_buffer(lowest);
+ if (!clone)
+ return -ENOMEM;
+
+ btrfs_release_path(path);
+ path->nodes[i] = clone;
+ path->slots[i] = slot;
+
+ return 0;
+}
/*
* btrfs_search_slot - look for a key in a tree and perform necessary
@@ -1684,6 +1701,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
const struct btrfs_key *key, struct btrfs_path *p,
int ins_len, int cow)
{
+ struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *b;
int slot;
int ret;
@@ -1725,6 +1743,11 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
min_write_lock_level = write_lock_level;
+ if (p->need_commit_sem) {
+ ASSERT(p->search_commit_root);
+ down_read(&fs_info->commit_root_sem);
+ }
+
again:
prev_cmp = -1;
b = btrfs_search_slot_get_root(root, p, write_lock_level);
@@ -1919,6 +1942,16 @@ cow_done:
done:
if (ret < 0 && !p->skip_release_on_error)
btrfs_release_path(p);
+
+ if (p->need_commit_sem) {
+ int ret2;
+
+ ret2 = finish_need_commit_sem_search(p);
+ up_read(&fs_info->commit_root_sem);
+ if (ret2)
+ ret = ret2;
+ }
+
return ret;
}
ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
@@ -4373,7 +4406,9 @@ int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
int level;
struct extent_buffer *c;
struct extent_buffer *next;
+ struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_key key;
+ bool need_commit_sem = false;
u32 nritems;
int ret;
int i;
@@ -4390,14 +4425,20 @@ again:
path->keep_locks = 1;
- if (time_seq)
+ if (time_seq) {
ret = btrfs_search_old_slot(root, &key, path, time_seq);
- else
+ } else {
+ if (path->need_commit_sem) {
+ path->need_commit_sem = 0;
+ need_commit_sem = true;
+ down_read(&fs_info->commit_root_sem);
+ }
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ }
path->keep_locks = 0;
if (ret < 0)
- return ret;
+ goto done;
nritems = btrfs_header_nritems(path->nodes[0]);
/*
@@ -4520,6 +4561,15 @@ again:
ret = 0;
done:
unlock_up(path, 0, 1, 0, NULL);
+ if (need_commit_sem) {
+ int ret2;
+
+ path->need_commit_sem = 1;
+ ret2 = finish_need_commit_sem_search(path);
+ up_read(&fs_info->commit_root_sem);
+ if (ret2)
+ ret = ret2;
+ }
return ret;
}
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index aa303669615d..0c92158cb50c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -572,7 +572,6 @@ enum {
/*
* Indicate that relocation of a chunk has started, it's set per chunk
* and is toggled between chunks.
- * Set, tested and cleared while holding fs_info::send_reloc_lock.
*/
BTRFS_FS_RELOC_RUNNING,
@@ -673,6 +672,12 @@ struct btrfs_fs_info {
u64 generation;
u64 last_trans_committed;
+ /*
+ * Generation of the last transaction used for block group relocation
+ * since the filesystem was last mounted (or 0 if none happened yet).
+ * Must be written and read while holding btrfs_fs_info::commit_root_sem.
+ */
+ u64 last_reloc_trans;
u64 avg_delayed_ref_runtime;
/*
@@ -1003,13 +1008,6 @@ struct btrfs_fs_info {
struct crypto_shash *csum_shash;
- spinlock_t send_reloc_lock;
- /*
- * Number of send operations in progress.
- * Updated while holding fs_info::send_reloc_lock.
- */
- int send_in_progress;
-
/* Type of exclusive operation running, protected by super_lock */
enum btrfs_exclusive_operation exclusive_operation;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7bf01f4fc92e..fc7dd5109806 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3023,6 +3023,7 @@ static int __cold init_tree_roots(struct btrfs_fs_info *fs_info)
/* All successful */
fs_info->generation = generation;
fs_info->last_trans_committed = generation;
+ fs_info->last_reloc_trans = 0;
/* Always begin writing backup roots after the one being used */
if (backup_index < 0) {
@@ -3159,9 +3160,6 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
spin_lock_init(&fs_info->swapfile_pins_lock);
fs_info->swapfile_pins = RB_ROOT;
- spin_lock_init(&fs_info->send_reloc_lock);
- fs_info->send_in_progress = 0;
-
fs_info->bg_reclaim_threshold = BTRFS_DEFAULT_RECLAIM_THRESH;
INIT_WORK(&fs_info->reclaim_bgs_work, btrfs_reclaim_bgs_work);
}
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 831c55708c88..775aff5a2c26 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3859,25 +3859,14 @@ out:
* 0 success
* -EINPROGRESS operation is already in progress, that's probably a bug
* -ECANCELED cancellation request was set before the operation started
- * -EAGAIN can not start because there are ongoing send operations
*/
static int reloc_chunk_start(struct btrfs_fs_info *fs_info)
{
- spin_lock(&fs_info->send_reloc_lock);
- if (fs_info->send_in_progress) {
- btrfs_warn_rl(fs_info,
-"cannot run relocation while send operations are in progress (%d in progress)",
- fs_info->send_in_progress);
- spin_unlock(&fs_info->send_reloc_lock);
- return -EAGAIN;
- }
if (test_and_set_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) {
/* This should not happen */
- spin_unlock(&fs_info->send_reloc_lock);
btrfs_err(fs_info, "reloc already running, cannot start");
return -EINPROGRESS;
}
- spin_unlock(&fs_info->send_reloc_lock);
if (atomic_read(&fs_info->reloc_cancel_req) > 0) {
btrfs_info(fs_info, "chunk relocation canceled on start");
@@ -3899,9 +3888,7 @@ static void reloc_chunk_end(struct btrfs_fs_info *fs_info)
/* Requested after start, clear bit first so any waiters can continue */
if (atomic_read(&fs_info->reloc_cancel_req) > 0)
btrfs_info(fs_info, "chunk relocation canceled during operation");
- spin_lock(&fs_info->send_reloc_lock);
clear_and_wake_up_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags);
- spin_unlock(&fs_info->send_reloc_lock);
atomic_set(&fs_info->reloc_cancel_req, 0);
}
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 6bdcb9d481d5..d8ccb62aa7d2 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -24,6 +24,7 @@
#include "transaction.h"
#include "compression.h"
#include "xattr.h"
+#include "print-tree.h"
/*
* Maximum number of references an extent can have in order for us to attempt to
@@ -98,6 +99,15 @@ struct send_ctx {
struct btrfs_key *cmp_key;
/*
+ * Keep track of the generation of the last transaction that was used
+ * for relocating a block group. This is periodically checked in order
+ * to detect if a relocation happened since the last check, so that we
+ * don't operate on stale extent buffers for nodes (level >= 1) or on
+ * stale disk_bytenr values of file extent items.
+ */
+ u64 last_reloc_trans;
+
+ /*
* infos of the currently processed inode. In case of deleted inodes,
* these are the values from the deleted inode.
*/
@@ -1421,6 +1431,26 @@ static int find_extent_clone(struct send_ctx *sctx,
if (ret < 0)
goto out;
+ down_read(&fs_info->commit_root_sem);
+ if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
+ /*
+ * A transaction commit for a transaction in which block group
+ * relocation was done just happened.
+ * The disk_bytenr of the file extent item we processed is
+ * possibly stale, referring to the extent's location before
+ * relocation. So act as if we haven't found any clone sources
+ * and fallback to write commands, which will read the correct
+ * data from the new extent location. Otherwise we will fail
+ * below because we haven't found our own back reference or we
+ * could be getting incorrect sources in case the old extent
+ * was already reallocated after the relocation.
+ */
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOENT;
+ goto out;
+ }
+ up_read(&fs_info->commit_root_sem);
+
if (!backref_ctx.found_itself) {
/* found a bug in backref code? */
ret = -EIO;
@@ -6583,6 +6613,50 @@ static int changed_cb(struct btrfs_path *left_path,
{
int ret = 0;
+ /*
+ * We can not hold the commit root semaphore here. This is because in
+ * the case of sending and receiving to the same filesystem, using a
+ * pipe, could result in a deadlock:
+ *
+ * 1) The task running send blocks on the pipe because it's full;
+ *
+ * 2) The task running receive, which is the only consumer of the pipe,
+ * is waiting for a transaction commit (for example due to a space
+ * reservation when doing a write or triggering a transaction commit
+ * when creating a subvolume);
+ *
+ * 3) The transaction is waiting to write lock the commit root semaphore,
+ * but can not acquire it since it's being held at 1).
+ *
+ * Down this call chain we write to the pipe through kernel_write().
+ * The same type of problem can also happen when sending to a file that
+ * is stored in the same filesystem - when reserving space for a write
+ * into the file, we can trigger a transaction commit.
+ *
+ * Our caller has supplied us with clones of leaves from the send and
+ * parent roots, so we're safe here from a concurrent relocation and
+ * further reallocation of metadata extents while we are here. Below we
+ * also assert that the leaves are clones.
+ */
+ lockdep_assert_not_held(&sctx->send_root->fs_info->commit_root_sem);
+
+ /*
+ * We always have a send root, so left_path is never NULL. We will not
+ * have a leaf when we have reached the end of the send root but have
+ * not yet reached the end of the parent root.
+ */
+ if (left_path->nodes[0])
+ ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
+ &left_path->nodes[0]->bflags));
+ /*
+ * When doing a full send we don't have a parent root, so right_path is
+ * NULL. When doing an incremental send, we may have reached the end of
+ * the parent root already, so we don't have a leaf at right_path.
+ */
+ if (right_path && right_path->nodes[0])
+ ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
+ &right_path->nodes[0]->bflags));
+
if (result == BTRFS_COMPARE_TREE_SAME) {
if (key->type == BTRFS_INODE_REF_KEY ||
key->type == BTRFS_INODE_EXTREF_KEY) {
@@ -6629,14 +6703,46 @@ out:
return ret;
}
+static int search_key_again(const struct send_ctx *sctx,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ const struct btrfs_key *key)
+{
+ int ret;
+
+ if (!path->need_commit_sem)
+ lockdep_assert_held_read(&root->fs_info->commit_root_sem);
+
+ /*
+ * Roots used for send operations are readonly and no one can add,
+ * update or remove keys from them, so we should be able to find our
+ * key again. The only exception is deduplication, which can operate on
+ * readonly roots and add, update or remove keys to/from them - but at
+ * the moment we don't allow it to run in parallel with send.
+ */
+ ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+ ASSERT(ret <= 0);
+ if (ret > 0) {
+ btrfs_print_tree(path->nodes[path->lowest_level], false);
+ btrfs_err(root->fs_info,
+"send: key (%llu %u %llu) not found in %s root %llu, lowest_level %d, slot %d",
+ key->objectid, key->type, key->offset,
+ (root == sctx->parent_root ? "parent" : "send"),
+ root->root_key.objectid, path->lowest_level,
+ path->slots[path->lowest_level]);
+ return -EUCLEAN;
+ }
+
+ return ret;
+}
+
static int full_send_tree(struct send_ctx *sctx)
{
int ret;
struct btrfs_root *send_root = sctx->send_root;
struct btrfs_key key;
+ struct btrfs_fs_info *fs_info = send_root->fs_info;
struct btrfs_path *path;
- struct extent_buffer *eb;
- int slot;
path = alloc_path_for_send();
if (!path)
@@ -6647,6 +6753,10 @@ static int full_send_tree(struct send_ctx *sctx)
key.type = BTRFS_INODE_ITEM_KEY;
key.offset = 0;
+ down_read(&fs_info->commit_root_sem);
+ sctx->last_reloc_trans = fs_info->last_reloc_trans;
+ up_read(&fs_info->commit_root_sem);
+
ret = btrfs_search_slot_for_read(send_root, &key, path, 1, 0);
if (ret < 0)
goto out;
@@ -6654,15 +6764,35 @@ static int full_send_tree(struct send_ctx *sctx)
goto out_finish;
while (1) {
- eb = path->nodes[0];
- slot = path->slots[0];
- btrfs_item_key_to_cpu(eb, &key, slot);
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
ret = changed_cb(path, NULL, &key,
BTRFS_COMPARE_TREE_NEW, sctx);
if (ret < 0)
goto out;
+ down_read(&fs_info->commit_root_sem);
+ if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
+ sctx->last_reloc_trans = fs_info->last_reloc_trans;
+ up_read(&fs_info->commit_root_sem);
+ /*
+ * A transaction used for relocating a block group was
+ * committed or is about to finish its commit. Release
+ * our path (leaf) and restart the search, so that we
+ * avoid operating on any file extent items that are
+ * stale, with a disk_bytenr that reflects a pre
+ * relocation value. This way we avoid as much as
+ * possible to fallback to regular writes when checking
+ * if we can clone file ranges.
+ */
+ btrfs_release_path(path);
+ ret = search_key_again(sctx, send_root, path, &key);
+ if (ret < 0)
+ goto out;
+ } else {
+ up_read(&fs_info->commit_root_sem);
+ }
+
ret = btrfs_next_item(send_root, path);
if (ret < 0)
goto out;
@@ -6680,6 +6810,20 @@ out:
return ret;
}
+static int replace_node_with_clone(struct btrfs_path *path, int level)
+{
+ struct extent_buffer *clone;
+
+ clone = btrfs_clone_extent_buffer(path->nodes[level]);
+ if (!clone)
+ return -ENOMEM;
+
+ free_extent_buffer(path->nodes[level]);
+ path->nodes[level] = clone;
+
+ return 0;
+}
+
static int tree_move_down(struct btrfs_path *path, int *level, u64 reada_min_gen)
{
struct extent_buffer *eb;
@@ -6689,6 +6833,8 @@ static int tree_move_down(struct btrfs_path *path, int *level, u64 reada_min_gen
u64 reada_max;
u64 reada_done = 0;
+ lockdep_assert_held_read(&parent->fs_info->commit_root_sem);
+
BUG_ON(*level == 0);
eb = btrfs_read_node_slot(parent, slot);
if (IS_ERR(eb))
@@ -6712,6 +6858,10 @@ static int tree_move_down(struct btrfs_path *path, int *level, u64 reada_min_gen
path->nodes[*level - 1] = eb;
path->slots[*level - 1] = 0;
(*level)--;
+
+ if (*level == 0)
+ return replace_node_with_clone(path, 0);
+
return 0;
}
@@ -6725,8 +6875,10 @@ static int tree_move_next_or_upnext(struct btrfs_path *path,
path->slots[*level]++;
while (path->slots[*level] >= nritems) {
- if (*level == root_level)
+ if (*level == root_level) {
+ path->slots[*level] = nritems - 1;
return -1;
+ }
/* move upnext */
path->slots[*level] = 0;
@@ -6758,14 +6910,20 @@ static int tree_advance(struct btrfs_path *path,
} else {
ret = tree_move_down(path, level, reada_min_gen);
}
- if (ret >= 0) {
- if (*level == 0)
- btrfs_item_key_to_cpu(path->nodes[*level], key,
- path->slots[*level]);
- else
- btrfs_node_key_to_cpu(path->nodes[*level], key,
- path->slots[*level]);
- }
+
+ /*
+ * Even if we have reached the end of a tree, ret is -1, update the key
+ * anyway, so that in case we need to restart due to a block group
+ * relocation, we can assert that the last key of the root node still
+ * exists in the tree.
+ */
+ if (*level == 0)
+ btrfs_item_key_to_cpu(path->nodes[*level], key,
+ path->slots[*level]);
+ else
+ btrfs_node_key_to_cpu(path->nodes[*level], key,
+ path->slots[*level]);
+
return ret;
}
@@ -6795,6 +6953,97 @@ static int tree_compare_item(struct btrfs_path *left_path,
}
/*
+ * A transaction used for relocating a block group was committed or is about to
+ * finish its commit. Release our paths and restart the search, so that we are
+ * not using stale extent buffers:
+ *
+ * 1) For levels > 0, we are only holding references of extent buffers, without
+ * any locks on them, which does not prevent them from having been relocated
+ * and reallocated after the last time we released the commit root semaphore.
+ * The exception are the root nodes, for which we always have a clone, see
+ * the comment at btrfs_compare_trees();
+ *
+ * 2) For leaves, level 0, we are holding copies (clones) of extent buffers, so
+ * we are safe from the concurrent relocation and reallocation. However they
+ * can have file extent items with a pre relocation disk_bytenr value, so we
+ * restart the start from the current commit roots and clone the new leaves so
+ * that we get the post relocation disk_bytenr values. Not doing so, could
+ * make us clone the wrong data in case there are new extents using the old
+ * disk_bytenr that happen to be shared.
+ */
+static int restart_after_relocation(struct btrfs_path *left_path,
+ struct btrfs_path *right_path,
+ const struct btrfs_key *left_key,
+ const struct btrfs_key *right_key,
+ int left_level,
+ int right_level,
+ const struct send_ctx *sctx)
+{
+ int root_level;
+ int ret;
+
+ lockdep_assert_held_read(&sctx->send_root->fs_info->commit_root_sem);
+
+ btrfs_release_path(left_path);
+ btrfs_release_path(right_path);
+
+ /*
+ * Since keys can not be added or removed to/from our roots because they
+ * are readonly and we do not allow deduplication to run in parallel
+ * (which can add, remove or change keys), the layout of the trees should
+ * not change.
+ */
+ left_path->lowest_level = left_level;
+ ret = search_key_again(sctx, sctx->send_root, left_path, left_key);
+ if (ret < 0)
+ return ret;
+
+ right_path->lowest_level = right_level;
+ ret = search_key_again(sctx, sctx->parent_root, right_path, right_key);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * If the lowest level nodes are leaves, clone them so that they can be
+ * safely used by changed_cb() while not under the protection of the
+ * commit root semaphore, even if relocation and reallocation happens in
+ * parallel.
+ */
+ if (left_level == 0) {
+ ret = replace_node_with_clone(left_path, 0);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (right_level == 0) {
+ ret = replace_node_with_clone(right_path, 0);
+ if (ret < 0)
+ return ret;
+ }
+
+ /*
+ * Now clone the root nodes (unless they happen to be the leaves we have
+ * already cloned). This is to protect against concurrent snapshotting of
+ * the send and parent roots (see the comment at btrfs_compare_trees()).
+ */
+ root_level = btrfs_header_level(sctx->send_root->commit_root);
+ if (root_level > 0) {
+ ret = replace_node_with_clone(left_path, root_level);
+ if (ret < 0)
+ return ret;
+ }
+
+ root_level = btrfs_header_level(sctx->parent_root->commit_root);
+ if (root_level > 0) {
+ ret = replace_node_with_clone(right_path, root_level);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+/*
* This function compares two trees and calls the provided callback for
* every changed/new/deleted item it finds.
* If shared tree blocks are encountered, whole subtrees are skipped, making
@@ -6822,10 +7071,10 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
int right_root_level;
int left_level;
int right_level;
- int left_end_reached;
- int right_end_reached;
- int advance_left;
- int advance_right;
+ int left_end_reached = 0;
+ int right_end_reached = 0;
+ int advance_left = 0;
+ int advance_right = 0;
u64 left_blockptr;
u64 right_blockptr;
u64 left_gen;
@@ -6893,12 +7142,18 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
down_read(&fs_info->commit_root_sem);
left_level = btrfs_header_level(left_root->commit_root);
left_root_level = left_level;
+ /*
+ * We clone the root node of the send and parent roots to prevent races
+ * with snapshot creation of these roots. Snapshot creation COWs the
+ * root node of a tree, so after the transaction is committed the old
+ * extent can be reallocated while this send operation is still ongoing.
+ * So we clone them, under the commit root semaphore, to be race free.
+ */
left_path->nodes[left_level] =
btrfs_clone_extent_buffer(left_root->commit_root);
if (!left_path->nodes[left_level]) {
- up_read(&fs_info->commit_root_sem);
ret = -ENOMEM;
- goto out;
+ goto out_unlock;
}
right_level = btrfs_header_level(right_root->commit_root);
@@ -6906,9 +7161,8 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
right_path->nodes[right_level] =
btrfs_clone_extent_buffer(right_root->commit_root);
if (!right_path->nodes[right_level]) {
- up_read(&fs_info->commit_root_sem);
ret = -ENOMEM;
- goto out;
+ goto out_unlock;
}
/*
* Our right root is the parent root, while the left root is the "send"
@@ -6918,7 +7172,6 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
* will need to read them at some point.
*/
reada_min_gen = btrfs_header_generation(right_root->commit_root);
- up_read(&fs_info->commit_root_sem);
if (left_level == 0)
btrfs_item_key_to_cpu(left_path->nodes[left_level],
@@ -6933,11 +7186,26 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
btrfs_node_key_to_cpu(right_path->nodes[right_level],
&right_key, right_path->slots[right_level]);
- left_end_reached = right_end_reached = 0;
- advance_left = advance_right = 0;
+ sctx->last_reloc_trans = fs_info->last_reloc_trans;
while (1) {
- cond_resched();
+ if (need_resched() ||
+ rwsem_is_contended(&fs_info->commit_root_sem)) {
+ up_read(&fs_info->commit_root_sem);
+ cond_resched();
+ down_read(&fs_info->commit_root_sem);
+ }
+
+ if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
+ ret = restart_after_relocation(left_path, right_path,
+ &left_key, &right_key,
+ left_level, right_level,
+ sctx);
+ if (ret < 0)
+ goto out_unlock;
+ sctx->last_reloc_trans = fs_info->last_reloc_trans;
+ }
+
if (advance_left && !left_end_reached) {
ret = tree_advance(left_path, &left_level,
left_root_level,
@@ -6946,7 +7214,7 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
if (ret == -1)
left_end_reached = ADVANCE;
else if (ret < 0)
- goto out;
+ goto out_unlock;
advance_left = 0;
}
if (advance_right && !right_end_reached) {
@@ -6957,54 +7225,55 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
if (ret == -1)
right_end_reached = ADVANCE;
else if (ret < 0)
- goto out;
+ goto out_unlock;
advance_right = 0;
}
if (left_end_reached && right_end_reached) {
ret = 0;
- goto out;
+ goto out_unlock;
} else if (left_end_reached) {
if (right_level == 0) {
+ up_read(&fs_info->commit_root_sem);
ret = changed_cb(left_path, right_path,
&right_key,
BTRFS_COMPARE_TREE_DELETED,
sctx);
if (ret < 0)
goto out;
+ down_read(&fs_info->commit_root_sem);
}
advance_right = ADVANCE;
continue;
} else if (right_end_reached) {
if (left_level == 0) {
+ up_read(&fs_info->commit_root_sem);
ret = changed_cb(left_path, right_path,
&left_key,
BTRFS_COMPARE_TREE_NEW,
sctx);
if (ret < 0)
goto out;
+ down_read(&fs_info->commit_root_sem);
}
advance_left = ADVANCE;
continue;
}
if (left_level == 0 && right_level == 0) {
+ up_read(&fs_info->commit_root_sem);
cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
if (cmp < 0) {
ret = changed_cb(left_path, right_path,
&left_key,
BTRFS_COMPARE_TREE_NEW,
sctx);
- if (ret < 0)
- goto out;
advance_left = ADVANCE;
} else if (cmp > 0) {
ret = changed_cb(left_path, right_path,
&right_key,
BTRFS_COMPARE_TREE_DELETED,
sctx);
- if (ret < 0)
- goto out;
advance_right = ADVANCE;
} else {
enum btrfs_compare_tree_result result;
@@ -7018,11 +7287,13 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
result = BTRFS_COMPARE_TREE_SAME;
ret = changed_cb(left_path, right_path,
&left_key, result, sctx);
- if (ret < 0)
- goto out;
advance_left = ADVANCE;
advance_right = ADVANCE;
}
+
+ if (ret < 0)
+ goto out;
+ down_read(&fs_info->commit_root_sem);
} else if (left_level == right_level) {
cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
if (cmp < 0) {
@@ -7062,6 +7333,8 @@ static int btrfs_compare_trees(struct btrfs_root *left_root,
}
}
+out_unlock:
+ up_read(&fs_info->commit_root_sem);
out:
btrfs_free_path(left_path);
btrfs_free_path(right_path);
@@ -7411,21 +7684,7 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
if (ret)
goto out;
- spin_lock(&fs_info->send_reloc_lock);
- if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) {
- spin_unlock(&fs_info->send_reloc_lock);
- btrfs_warn_rl(fs_info,
- "cannot run send because a relocation operation is in progress");
- ret = -EAGAIN;
- goto out;
- }
- fs_info->send_in_progress++;
- spin_unlock(&fs_info->send_reloc_lock);
-
ret = send_subvol(sctx);
- spin_lock(&fs_info->send_reloc_lock);
- fs_info->send_in_progress--;
- spin_unlock(&fs_info->send_reloc_lock);
if (ret < 0)
goto out;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5eadb17b971b..03de89b45f27 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -169,6 +169,10 @@ static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING);
down_write(&fs_info->commit_root_sem);
+
+ if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
+ fs_info->last_reloc_trans = trans->transid;
+
list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
dirty_list) {
list_del_init(&root->dirty_list);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-17 18:08:17 +0000