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ntfs: check the dirty-state commit on remount and unmount

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The remount-to-read-only path commits the updated volume flags with
ntfs_commit_inode(), a void wrapper around __ntfs_write_inode(), and
ignores the blkdev_issue_flush() return value, so a failed commit or
flush is reported as success.  Once the remount has succeeded no
persistence point is ever reached again: ntfs_put_super() skips
read-only superblocks and the VFS never syncs one, so fail the
remount unless the commit and the flush succeed.  The superblock
then stays read-write and ntfs_put_super() retries the persistence
at unmount.  The errors=remount-ro downgrade does not go through
ntfs_reconfigure() and is unchanged.

A zero-return commit is not trusted blindly: write_mft_record()
redirties the record on allocation failure and reports success, so
the $Volume inode is required to be clean afterwards.

ntfs_put_super() discards the same commit error.  Call
__ntfs_write_inode() there with the same dirty re-check and warn on
failure, as put_super() cannot return an error.  The commit is
skipped when the dirty-state sync itself failed, as that could write
back an inconsistent flag state; a record left dirty by an earlier
update is still committed at evict time.

NVolErrors() is deliberately not used to detect the failure: it is
sticky for the lifetime of the mount, so it cannot distinguish a
fresh commit failure from errors recorded before the remount.

Hibernated volumes: ntfs_sync_volume_dirty_state() is a no-op for
them and never dirties the $Volume inode on such a mount, since the
on-disk flags are already dirty and ntfs_set_volume_flags() has
nothing to change.  The commit only runs if something dirtied the
inode independently, as before this patch; mounting hibernated
volumes read-only removes even that.

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>
This commit is contained in:
Hongling Zeng 2026-09-15 16:32:51 +08:00 committed by Namjae Jeon
parent 4a1bb54f57
commit 1a3883b368
1 changed files with 54 additions and 22 deletions
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76
fs/ntfs/super.c
View File

@ -269,6 +269,7 @@ static int ntfs_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
struct ntfs_volume *vol = NTFS_SB(sb);
int err;
ntfs_debug("Entering with remount");
@ -331,14 +332,39 @@ static int ntfs_reconfigure(struct fs_context *fc)
* and ntfs_put_super() skips them, so the only remaining
* write would be the evict-time commit at unmount, which
* a crash never reaches. An error recorded only after
* the remount is still never persisted.
* the remount is still never persisted; a failed commit
* or flush fails the remount, leaving the superblock
* read-write so ntfs_put_super() retries at unmount.
*/
if (ntfs_sync_volume_dirty_state(vol)) {
err = ntfs_sync_volume_dirty_state(vol);
if (err) {
ntfs_warning(sb,
"Failed to update dirty bit in volume information flags. Run chkdsk.");
} else if (NInoDirty(NTFS_I(vol->vol_ino))) {
ntfs_commit_inode(vol->vol_ino);
blkdev_issue_flush(sb->s_bdev);
return err;
}
if (NInoDirty(NTFS_I(vol->vol_ino))) {
/* ntfs_commit_inode() would discard the error. */
err = __ntfs_write_inode(vol->vol_ino, 1);
if (err) {
ntfs_warning(sb,
"Failed to commit volume information flags. Run chkdsk.");
return err;
}
/*
* write_mft_record() redirties the record on
* -ENOMEM and still reports success.
*/
if (NInoDirty(NTFS_I(vol->vol_ino))) {
ntfs_warning(sb,
"Volume information flags remain dirty after commit. Run chkdsk.");
return -EIO;
}
err = blkdev_issue_flush(sb->s_bdev);
if (err) {
ntfs_warning(sb,
"Failed to flush volume information flags. Run chkdsk.");
return err;
}
}
}
@ -1944,26 +1970,32 @@ static void ntfs_put_super(struct super_block *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)) {
} else {
/*
* The dirty bit is on disk now; only warn when the
* sync actually succeeded, or this message would
* contradict the one above.
* __ntfs_write_inode(), not the void
* ntfs_commit_inode() wrapper: the error can only
* be warned about here. The mirror inode is only
* released below: writing the $Volume record (mft
* record number 3, below vol->mftmirr_size) mirrors
* it through ntfs_sync_mft_mirror(), which fails
* with -EIO once vol->mftmirr_ino is gone.
*/
ntfs_warning(sb,
"Volume has errors. Leaving volume marked dirty. Run chkdsk.");
if (__ntfs_write_inode(vol->vol_ino, 1)) {
ntfs_warning(sb,
"Failed to commit volume information flags. Run chkdsk.");
} else if (NInoDirty(NTFS_I(vol->vol_ino))) {
ntfs_warning(sb,
"Volume information flags remain dirty after commit. Run chkdsk.");
} else if (NVolErrors(vol)) {
/*
* Only warn once the commit has succeeded,
* or this could contradict a failure
* reported above.
*/
ntfs_warning(sb,
"Volume has errors. Leaving volume marked dirty. Run chkdsk.");
}
}
/*
* Commits the updated volume flags if they were written.
* The mft mirror must still be around for this: the
* $Volume record (mft record number 3, below
* vol->mftmirr_size) is mirrored by write_mft_record()
* through ntfs_sync_mft_mirror(), which fails with -EIO
* and leaves the mirror stale once vol->mftmirr_ino is
* gone, so the mirror inode is only released after this
* commit.
*/
ntfs_commit_inode(vol->vol_ino);
}
/*