xfs: adjust parent pointer scrubber for sb-rooted metadata files

Starting with the metadata directory feature, we're allowed to call the
directory and parent pointer scrubbers for every metadata file,
including the ones that are children of the superblock.

For these children, checking the link count against the number of parent
pointers is a bit funny -- there's no such thing as a parent pointer for
a child of the superblock since there's no corresponding dirent.  For
purposes of validating nlink, we pretend that there is a parent pointer.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Author: Darrick J. Wong

fs/xfs/scrub/parent.c

@@ -720,6 +720,14 @@ xchk_parent_count_pptrs(
 			 pp->pptrs_found == 0)
 			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
 	} else {
+		/*
+		 * Starting with metadir, we allow checking of parent pointers
+		 * of non-directory files that are children of the superblock.
+		 * Pretend that we found a parent pointer attr.
+		 */
+		if (xfs_has_metadir(sc->mp) && xchk_inode_is_sb_rooted(sc->ip))
+			pp->pptrs_found++;
+
 		if (VFS_I(sc->ip)->i_nlink != pp->pptrs_found)
 			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
 	}

fs/xfs/scrub/parent_repair.c

@@ -1354,21 +1354,40 @@ STATIC int
 xrep_parent_rebuild_tree(
 	struct xrep_parent	*rp)
 {
+	struct xfs_scrub	*sc = rp->sc;
+	bool			try_adoption;
 	int			error;
 
-	if (xfs_has_parent(rp->sc->mp)) {
+	if (xfs_has_parent(sc->mp)) {
 		error = xrep_parent_rebuild_pptrs(rp);
 		if (error)
 			return error;
 	}
 
-	if (rp->pscan.parent_ino == NULLFSINO) {
-		if (xrep_orphanage_can_adopt(rp->sc))
+	/*
+	 * Any file with no parent could be adopted.  This check happens after
+	 * rebuilding the parent pointer structure because we might have cycled
+	 * the ILOCK during that process.
+	 */
+	try_adoption = rp->pscan.parent_ino == NULLFSINO;
+
+	/*
+	 * Starting with metadir, we allow checking of parent pointers
+	 * of non-directory files that are children of the superblock.
+	 * Lack of parent is ok here.
+	 */
+	if (try_adoption && xfs_has_metadir(sc->mp) &&
+	    xchk_inode_is_sb_rooted(sc->ip))
+		try_adoption = false;
+
+	if (try_adoption) {
+		if (xrep_orphanage_can_adopt(sc))
 			return xrep_parent_move_to_orphanage(rp);
 		return -EFSCORRUPTED;
+
 	}
 
-	if (S_ISDIR(VFS_I(rp->sc->ip)->i_mode))
+	if (S_ISDIR(VFS_I(sc->ip)->i_mode))
 		return xrep_parent_reset_dotdot(rp);
 
 	return 0;
@@ -1422,6 +1441,14 @@ xrep_parent_set_nondir_nlink(
 	if (error)
 		return error;
 
+	/*
+	 * Starting with metadir, we allow checking of parent pointers of
+	 * non-directory files that are children of the superblock.  Pretend
+	 * that we found a parent pointer attr.
+	 */
+	if (xfs_has_metadir(sc->mp) && xchk_inode_is_sb_rooted(sc->ip))
+		rp->parents++;
+
 	if (rp->parents > 0 && xfs_inode_on_unlinked_list(ip)) {
 		xfs_trans_ijoin(sc->tp, sc->ip, 0);
 		joined = true;