ntfs: do not clear the volume dirty bit during sync

ntfs_sync_fs() clears VOLUME_IS_DIRTY while the volume is still mounted
read-write, so a sync running concurrently with an in-flight metadata
modification can clear and persist a bit that was just set: the
modification then lands on a volume that is clean on disk, and a crash
does not run chkdsk.

Stop clearing the bit in ntfs_sync_fs() and leave the clearing to the
remount-to-read-only path, which the VFS reaches only after
sb_prepare_remount_readonly() has drained in-flight writers, and to
ntfs_put_super(), which runs after evict_inodes() on a quiesced
filesystem.  A mounted read-write volume now keeps the dirty bit until
it is dismounted cleanly, which matches the NTFS semantics; the cost is
a needless chkdsk if the machine crashes between a sync and the unmount.

A recorded error state is still persisted right away when the
filesystem is synced: with NVolErrors() set,
ntfs_sync_volume_dirty_state() can only set the bit, never clear it,
so it cannot lose a modification the way the old unconditional call
did.  This keeps the error report from being lost to a crash on a
volume that has seen no modification; an error recorded after the
last sync is still only persisted at the next quiescent transition.

sync_blockdev() and blkdev_issue_flush() are both called and the first
error is returned, so a writeback failure neither hides a flush failure
nor skips it.

A RWF_NOWAIT write still blocks in the marking when the volume looks
clean, as it already did on the base; a non-blocking marking is
follow-up work.

Reported-by: Baolin Liu <liubaolin@kylinos.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Reviewed-by: Baolin Liu <liubaolin@kylinos.cn>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

0 files changed, 0 insertions, 0 deletions