[PATCH 0/2] ntfs: super.c fixes for MFT mirror check and sync_fs

[DaeMyung Kang <charsyam@gmail.com>]

This series fixes two regressions in fs/ntfs/super.c introduced by:

  6251f0b0de7d ("ntfs: update super block operations")

which switched the driver to the fs_context-based mount API and added
->sync_fs.

Patch 1 restores the missing memcmp() inside check_mft_mirror().  The
function still walks both $MFT and $MFTMirr records and computes a
per-record byte count to compare, but the actual comparison was dropped
when super block operations were updated.  As a result, mount silently
accepts a stale or inconsistent $MFTMirr as long as both records pass
the structural baad-record checks, defeating the purpose of having the
mirror.  With the comparison restored, a mismatch is reported at mount
time and the existing on_errors policy decides whether to convert to
read-only or proceed with NVolErrors set.

Patch 2 stops ntfs_sync_fs() from clearing VOLUME_IS_DIRTY.  sync_fs
can be called while the filesystem is still mounted read-write (for
example via sync(2) or periodic writeback), so clearing the dirty bit
there marks the volume clean before the mount lifetime has ended.  If
the system crashes after sync_fs() but before unmount or remount-ro,
the on-disk image is left looking cleanly shut down even though it is
not.  The legitimate clear paths in ntfs_put_super() and the RW->RO
remount path are kept intact and gate on !NVolErrors().

Both patches apply on top of ntfs-next.

DaeMyung Kang (2):
  ntfs: restore $MFT mirror contents check
  ntfs: do not mark the volume clean from sync_fs

 fs/ntfs/super.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

-- 
2.43.0