ext4: protect WRITE_ZEROES written extents with orphan list

In ext4_alloc_file_blocks(), the WRITE_ZEROES path converts unwritten
extents to written in one transaction, while i_disksize is updated to
cover them only in a later transaction. A crash in between leaves
written extents beyond i_disksize on disk, which fsck will complain
about.

To fix this, add the inode to the orphan list in the same handle that
does the conversion, and remove it once i_disksize has caught up.
Also add a sanity check to ensure conversion does not extend beyond EOF.

Since ext4_alloc_file_blocks() is called from the fallocate() path,
partial allocation is safe. On partial conversion failure, advance
i_disksize only up to the boundary of successfully converted blocks, so
that orphan cleanup sees a consistent state. Document this behavior in
the function comment.

Reported-by: Jan Kara <jack@suse.cz>
Closes: https://lore.kernel.org/linux-ext4/3f6ao5amv7glbgigndtegcucgo3n34ij3lau6l3da3hgdxgn3v@ev66wv3r5umt/
Fixes: f4265b8d32c4 ("ext4: add FALLOC_FL_WRITE_ZEROES support")
Cc: stable@vger.kernel.org
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260729085918.3336221-3-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

0 files changed, 0 insertions, 0 deletions