6.6-stable review patch. If anyone has any objections, please let me know.
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From: Zhang Yi yi.zhang@huawei.com
commit 328a782cb138029182e521c08f50eb1587db955d upstream.
When freeing metadata blocks in nojournal mode, ext4_forget() calls bforget() to clear the dirty flag on the buffer_head and remvoe associated mappings. This is acceptable if the metadata has not yet begun to be written back. However, if the write-back has already started but is not yet completed, ext4_forget() will have no effect. Subsequently, ext4_mb_clear_bb() will immediately return the block to the mb allocator. This block can then be reallocated immediately, potentially causing an data corruption issue.
Fix this by clearing the buffer's dirty flag and waiting for the ongoing I/O to complete, ensuring that no further writes to stale data will occur.
Fixes: 16e08b14a455 ("ext4: cleanup clean_bdev_aliases() calls") Cc: stable@kernel.org Reported-by: Gao Xiang hsiangkao@linux.alibaba.com Closes: https://lore.kernel.org/linux-ext4/a9417096-9549-4441-9878-b1955b899b4e@huaw... Signed-off-by: Zhang Yi yi.zhang@huawei.com Reviewed-by: Jan Kara jack@suse.cz Message-ID: 20250916093337.3161016-3-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/ext4_jbd2.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/fs/ext4/ext4_jbd2.c +++ b/fs/ext4/ext4_jbd2.c @@ -277,9 +277,16 @@ int __ext4_forget(const char *where, uns bh, is_metadata, inode->i_mode, test_opt(inode->i_sb, DATA_FLAGS));
- /* In the no journal case, we can just do a bforget and return */ + /* + * In the no journal case, we should wait for the ongoing buffer + * to complete and do a forget. + */ if (!ext4_handle_valid(handle)) { - bforget(bh); + if (bh) { + clear_buffer_dirty(bh); + wait_on_buffer(bh); + __bforget(bh); + } return 0; }