[PATCH 2/3] xfs: xfs_iget in the directory scrubber needs to use UNTRUSTED

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

In commit 4b80ac64450f, we tried to strengthen the directory scrubber by
using the iget call to detect directory entries that point to
unallocated inodes.  Unfortunately, that commit neglected to pass
XFS_IGET_UNTRUSTED to xfs_iget, so we don't check the inode btree first.
If the inode number points to something that isn't even an inode
cluster, iget will throw corruption errors and return -EFSCORRUPTED,
which means that we fail to mark the directory corrupt.

Fixes: 4b80ac64450f ("xfs: scrub should mark a directory corrupt if any entries cannot be iget'd")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/dir.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)


diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
index 43a1cbf2ac67..61cd1330de42 100644
--- a/fs/xfs/scrub/dir.c
+++ b/fs/xfs/scrub/dir.c
@@ -59,19 +59,15 @@ xchk_dir_check_ftype(
 	}
 
 	/*
-	 * Grab the inode pointed to by the dirent.  We release the
-	 * inode before we cancel the scrub transaction.  Since we're
-	 * don't know a priori that releasing the inode won't trigger
-	 * eofblocks cleanup (which allocates what would be a nested
-	 * transaction), we can't use DONTCACHE here because DONTCACHE
-	 * inodes can trigger immediate inactive cleanup of the inode.
+	 * Grab the inode pointed to by the dirent.  Use UNTRUSTED here to
+	 * check the allocation status of the inode in the inode btrees.
 	 *
 	 * If _iget returns -EINVAL or -ENOENT then the child inode number is
 	 * garbage and the directory is corrupt.  If the _iget returns
 	 * -EFSCORRUPTED or -EFSBADCRC then the child is corrupt which is a
 	 *  cross referencing error.  Any other error is an operational error.
 	 */
-	error = xfs_iget(mp, sdc->sc->tp, inum, 0, 0, &ip);
+	error = xchk_iget(sdc->sc, inum, &ip);
 	if (error == -EINVAL || error == -ENOENT) {
 		error = -EFSCORRUPTED;
 		xchk_fblock_process_error(sdc->sc, XFS_DATA_FORK, 0, &error);