xfs: scrub should mark a directory corrupt if any entries cannot be iget'd

It's possible that xfs_iget can return EINVAL for inodes that the inobt
thinks are free, or ENOENT for inodes that look free.  If this is the
case, mark the directory corrupt immediately when we check ftype.  Note
that we already check the ftype of the '.' and '..' entries, so we
can skip the iget part since we already know the inode type for '.' and
we have a separate parent pointer scrubber for '..'.

Fixes: a5c46e5e ("xfs: scrub directory metadata")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/scrub/dir.c

@@ -66,8 +66,18 @@ xchk_dir_check_ftype(
 	 * 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.
+	 *
+	 * 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);
+	if (error == -EINVAL || error == -ENOENT) {
+		error = -EFSCORRUPTED;
+		xchk_fblock_process_error(sdc->sc, XFS_DATA_FORK, 0, &error);
+		goto out;
+	}
 	if (!xchk_fblock_xref_process_error(sdc->sc, XFS_DATA_FORK, offset,
 			&error))
 		goto out;
@@ -105,6 +115,7 @@ xchk_dir_actor(
 	struct xfs_name		xname;
 	xfs_ino_t		lookup_ino;
 	xfs_dablk_t		offset;
+	bool			checked_ftype = false;
 	int			error = 0;
 
 	sdc = container_of(dir_iter, struct xchk_dir_ctx, dir_iter);
@@ -133,6 +144,7 @@ xchk_dir_actor(
 		if (xfs_sb_version_hasftype(&mp->m_sb) && type != DT_DIR)
 			xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
 					offset);
+		checked_ftype = true;
 		if (ino != ip->i_ino)
 			xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
 					offset);
@@ -144,6 +156,7 @@ xchk_dir_actor(
 		if (xfs_sb_version_hasftype(&mp->m_sb) && type != DT_DIR)
 			xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
 					offset);
+		checked_ftype = true;
 		if (ip->i_ino == mp->m_sb.sb_rootino && ino != ip->i_ino)
 			xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
 					offset);
@@ -167,9 +180,11 @@ xchk_dir_actor(
 	}
 
 	/* Verify the file type.  This function absorbs error codes. */
-	error = xchk_dir_check_ftype(sdc, offset, lookup_ino, type);
-	if (error)
-		goto out;
+	if (!checked_ftype) {
+		error = xchk_dir_check_ftype(sdc, offset, lookup_ino, type);
+		if (error)
+			goto out;
+	}
 out:
 	/*
 	 * A negative error code returned here is supposed to cause the