[PATCH v4 4/4] ntfs: persist the dirty state after the final put_super() commits

[Hongling Zeng]

The just-in-case mftmirr/mft commits and the final write_inode_now()
in ntfs_put_super() can record NVolErrors() after the dirty state has
been persisted, so errors from those points would leave the volume
unmounted with a clean on-disk dirty bit - contradicting the "cannot
unmount clean" guarantee ntfs_sync_volume_dirty_state() is meant to
provide.

Move the persistence to the end of ntfs_put_super(): keep the gated
re-commits and the tail commits where they are, run
ntfs_sync_volume_dirty_state() and the $Volume commit after the last
write_inode_now(), and move the iput(vol->vol_ino) down so
vol->vol_ino stays available for the sync.

Reported-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
---
 fs/ntfs/super.c | 52 +++++++++++++++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 4b4af1ea8b09..b31ea2747f57 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -1826,26 +1826,13 @@ static void ntfs_put_super(struct super_block *sb)
 	ntfs_commit_inode(vol->mft_ino);
 
 	/*
-	 * If a read-write mount, persist the error state in the volume flags:
-	 * mark the volume clean if no volume errors have occurred, and make
-	 * sure VOLUME_IS_DIRTY is on disk if any have, so chkdsk runs on the
-	 * next mount.  Also, re-commit all affected inodes.
+	 * If a read-write mount, re-commit all affected inodes once more.
+	 * The dirty state itself is persisted at the end of ntfs_put_super(),
+	 * after the last commits and the final write_inode_now(): those can
+	 * still record errors via __ntfs_write_inode(), and the sync must
+	 * evaluate NVolErrors() with the last setter already run.
 	 */
 	if (!sb_rdonly(sb)) {
-		if (ntfs_sync_volume_dirty_state(vol)) {
-			ntfs_warning(sb,
-				"Failed to sync dirty bit in volume information flags.  Run chkdsk.");
-		} else if (NVolErrors(vol)) {
-			/*
-			 * The dirty bit is on disk now; only warn when the
-			 * sync actually succeeded, or this message would
-			 * contradict the one above.
-			 */
-			ntfs_warning(sb,
-				"Volume has errors.  Leaving volume marked dirty.  Run chkdsk.");
-		}
-		/* Commits the updated volume flags if they were written. */
-		ntfs_commit_inode(vol->vol_ino);
 		if (!NVolErrors(vol)) {
 			ntfs_commit_inode(vol->root_ino);
 			if (vol->mftmirr_ino)
@@ -1854,9 +1841,6 @@ static void ntfs_put_super(struct super_block *sb)
 		}
 	}
 
-	iput(vol->vol_ino);
-	vol->vol_ino = NULL;
-
 	/* NTFS 3.0+ specific clean up. */
 	if (vol->major_ver >= 3) {
 		if (vol->extend_ino) {
@@ -1897,10 +1881,36 @@ static void ntfs_put_super(struct super_block *sb)
 	ntfs_commit_inode(vol->mft_ino);
 	write_inode_now(vol->mft_ino, 1);
 
+	/*
+	 * If a read-write mount, persist the error state in the volume flags:
+	 * mark the volume clean if no volume errors have occurred, and make
+	 * sure VOLUME_IS_DIRTY is on disk if any have, so chkdsk runs on the
+	 * next mount.
+	 */
+	if (!sb_rdonly(sb)) {
+		if (ntfs_sync_volume_dirty_state(vol)) {
+			ntfs_warning(sb,
+				"Failed to sync dirty bit in volume information flags.  Run chkdsk.");
+		} else if (NVolErrors(vol)) {
+			/*
+			 * The dirty bit is on disk now; only warn when the
+			 * sync actually succeeded, or this message would
+			 * contradict the one above.
+			 */
+			ntfs_warning(sb,
+				"Volume has errors.  Leaving volume marked dirty.  Run chkdsk.");
+		}
+		/* Commits the updated volume flags if they were written. */
+		ntfs_commit_inode(vol->vol_ino);
+	}
+
 	iput(vol->mft_ino);
 	vol->mft_ino = NULL;
 	blkdev_issue_flush(sb->s_bdev);
 
+	iput(vol->vol_ino);
+	vol->vol_ino = NULL;
+
 	ntfs_volume_free(vol);
 }
 
-- 
2.25.1