[PATCH v10 0/6] ntfs: fix volume flag races and persist the recorded error state

[Hongling Zeng]

The fs/ntfs runtime metadata-corruption paths only record the in-memory
NVolErrors() flag, and the caller-side dirty-bit marking races with
ntfs_sync_fs(): a volume can end up with a clean on-disk dirty flag
despite modification or recorded corruption, so chkdsk never runs on
the next mount.  Based on ntfs/ntfs-next (9a05b5715cfa).

 1/4 makes the volume flag read-modify-write atomic under the
    $Volume mrec_lock;
 2/4 marks the volume dirty unconditionally on metadata changes,
    dropping the racy caller-side checks in file.c and namei.c;
 3/4 derives the on-disk dirty bit from the recorded error state at
    the persistence points (sync_fs, remount-ro, put_super) and never
    writes a hibernated volume;
 4/4 persists the dirty state after the final put_super() commits so
    late errors cannot unmount clean.

Changes in v10:

- Add 5/6: Stop clearing VOLUME_IS_DIRTY during sync. The bit is now
  cleared only on remount to read-only or clean unmount, preventing a
  crash during metadata updates from bypassing chkdsk. Verified in QEMU.

- Add 6/6: Check commit and flush errors during remount and unmount.
  Re-check NInoDirty() after __ntfs_write_inode(). A failed remount is
  rejected so unmount can retry; unmount failures are reported as warnings.


Hongling Zeng (4):
  ntfs: fix volume flag update races
  ntfs: set the volume dirty bit unconditionally on metadata changes
  ntfs: sync the volume dirty bit with the recorded error state
  ntfs: persist the dirty state after the final put_super() commits

 fs/ntfs/file.c   |  20 ++---
 fs/ntfs/namei.c  |  24 ++----
 fs/ntfs/ntfs.h   |   1 -
 fs/ntfs/super.c  | 191 ++++++++++++++++++++++++++++++++++++-----------
 fs/ntfs/volume.h |   4 +
 5 files changed, 171 insertions(+), 69 deletions(-)

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2.25.1