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authorShida Zhang2024-08-30 13:37:38 +0800
committerTheodore Ts'o2024-09-03 22:14:17 -0400
commitcb3de5fc876ee9ef2b830c9e6cdafac5c90903ef (patch)
tree09ce95a8a43a93b37459e97030f54259055ff7dd /fs/ext4
parent6b730a405037501a260d6efd24782d2737e65d07 (diff)
ext4: fix a potential assertion failure due to improperly dirtied buffer
On an old kernel version(4.19, ext3, data=journal, pagesize=64k), an assertion failure will occasionally be triggered by the line below: ----------- jbd2_journal_commit_transaction { ... J_ASSERT_BH(bh, !buffer_dirty(bh)); /* * The buffer on BJ_Forget list and not jbddirty means ... } ----------- The same condition may also be applied to the lattest kernel version. When blocksize < pagesize and we truncate a file, there can be buffers in the mapping tail page beyond i_size. These buffers will be filed to transaction's BJ_Forget list by ext4_journalled_invalidatepage() during truncation. When the transaction doing truncate starts committing, we can grow the file again. This calls __block_write_begin() which allocates new blocks under these buffers in the tail page we go through the branch: if (buffer_new(bh)) { clean_bdev_bh_alias(bh); if (folio_test_uptodate(folio)) { clear_buffer_new(bh); set_buffer_uptodate(bh); mark_buffer_dirty(bh); continue; } ... } Hence buffers on BJ_Forget list of the committing transaction get marked dirty and this triggers the jbd2 assertion. Teach ext4_block_write_begin() to properly handle files with data journalling by avoiding dirtying them directly. Instead of folio_zero_new_buffers() we use ext4_journalled_zero_new_buffers() which takes care of handling journalling. We also don't need to mark new uptodate buffers as dirty in ext4_block_write_begin(). That will be either done either by block_commit_write() in case of success or by folio_zero_new_buffers() in case of failure. Reported-by: Baolin Liu <liubaolin@kylinos.cn> Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20240830053739.3588573-4-zhangshida@kylinos.cn Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/ext4.h3
-rw-r--r--fs/ext4/inline.c7
-rw-r--r--fs/ext4/inode.c42
3 files changed, 40 insertions, 12 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8bd08637fe14..8cc15d00e5c8 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3853,7 +3853,8 @@ static inline int ext4_buffer_uptodate(struct buffer_head *bh)
return buffer_uptodate(bh);
}
-extern int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
+extern int ext4_block_write_begin(handle_t *handle, struct folio *folio,
+ loff_t pos, unsigned len,
get_block_t *get_block);
#endif /* __KERNEL__ */
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index b018a80fec7a..7ca4aca53162 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -601,10 +601,11 @@ retry:
goto out;
if (ext4_should_dioread_nolock(inode)) {
- ret = ext4_block_write_begin(folio, from, to,
+ ret = ext4_block_write_begin(handle, folio, from, to,
ext4_get_block_unwritten);
} else
- ret = ext4_block_write_begin(folio, from, to, ext4_get_block);
+ ret = ext4_block_write_begin(handle, folio, from, to,
+ ext4_get_block);
if (!ret && ext4_should_journal_data(inode)) {
ret = ext4_walk_page_buffers(handle, inode,
@@ -856,7 +857,7 @@ static int ext4_da_convert_inline_data_to_extent(struct address_space *mapping,
goto out;
}
- ret = ext4_block_write_begin(folio, 0, inline_size,
+ ret = ext4_block_write_begin(NULL, folio, 0, inline_size,
ext4_da_get_block_prep);
if (ret) {
up_read(&EXT4_I(inode)->xattr_sem);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0010f7004688..a11e2626b5f6 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -49,6 +49,11 @@
#include <trace/events/ext4.h>
+static void ext4_journalled_zero_new_buffers(handle_t *handle,
+ struct inode *inode,
+ struct folio *folio,
+ unsigned from, unsigned to);
+
static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
struct ext4_inode_info *ei)
{
@@ -1023,7 +1028,8 @@ int do_journal_get_write_access(handle_t *handle, struct inode *inode,
return ret;
}
-int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
+int ext4_block_write_begin(handle_t *handle, struct folio *folio,
+ loff_t pos, unsigned len,
get_block_t *get_block)
{
unsigned from = pos & (PAGE_SIZE - 1);
@@ -1037,6 +1043,7 @@ int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
struct buffer_head *bh, *head, *wait[2];
int nr_wait = 0;
int i;
+ bool should_journal_data = ext4_should_journal_data(inode);
BUG_ON(!folio_test_locked(folio));
BUG_ON(from > PAGE_SIZE);
@@ -1066,10 +1073,22 @@ int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
if (err)
break;
if (buffer_new(bh)) {
+ /*
+ * We may be zeroing partial buffers or all new
+ * buffers in case of failure. Prepare JBD2 for
+ * that.
+ */
+ if (should_journal_data)
+ do_journal_get_write_access(handle,
+ inode, bh);
if (folio_test_uptodate(folio)) {
- clear_buffer_new(bh);
+ /*
+ * Unlike __block_write_begin() we leave
+ * dirtying of new uptodate buffers to
+ * ->write_end() time or
+ * folio_zero_new_buffers().
+ */
set_buffer_uptodate(bh);
- mark_buffer_dirty(bh);
continue;
}
if (block_end > to || block_start < from)
@@ -1099,7 +1118,11 @@ int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len,
err = -EIO;
}
if (unlikely(err)) {
- folio_zero_new_buffers(folio, from, to);
+ if (should_journal_data)
+ ext4_journalled_zero_new_buffers(handle, inode, folio,
+ from, to);
+ else
+ folio_zero_new_buffers(folio, from, to);
} else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
for (i = 0; i < nr_wait; i++) {
int err2;
@@ -1197,10 +1220,11 @@ retry_journal:
folio_wait_stable(folio);
if (ext4_should_dioread_nolock(inode))
- ret = ext4_block_write_begin(folio, pos, len,
+ ret = ext4_block_write_begin(handle, folio, pos, len,
ext4_get_block_unwritten);
else
- ret = ext4_block_write_begin(folio, pos, len, ext4_get_block);
+ ret = ext4_block_write_begin(handle, folio, pos, len,
+ ext4_get_block);
if (!ret && ext4_should_journal_data(inode)) {
ret = ext4_walk_page_buffers(handle, inode,
folio_buffers(folio), from, to,
@@ -2926,7 +2950,8 @@ retry:
if (IS_ERR(folio))
return PTR_ERR(folio);
- ret = ext4_block_write_begin(folio, pos, len, ext4_da_get_block_prep);
+ ret = ext4_block_write_begin(NULL, folio, pos, len,
+ ext4_da_get_block_prep);
if (ret < 0) {
folio_unlock(folio);
folio_put(folio);
@@ -6183,7 +6208,8 @@ retry_alloc:
if (folio_pos(folio) + len > size)
len = size - folio_pos(folio);
- err = __block_write_begin(&folio->page, 0, len, ext4_get_block);
+ err = ext4_block_write_begin(handle, folio, 0, len,
+ ext4_get_block);
if (!err) {
ret = VM_FAULT_SIGBUS;
if (ext4_journal_folio_buffers(handle, folio, len))