When verifying '..' after VFS_VGET() in ufs_lookup(), do not return

error if '..' is still there but changed between lookup and check.
Start relookup instead. Rename is supposed to change '..' reference
atomically, so transient failures introduced by r191137 are wrong.

While rearranging the code to allow lookup restart in ufs_lookup(),
remove the comment that only distracts the reader.

Noted and reviewed by:	tegge
Also reported by:	pho
MFC after:	1 month

1 files changed, 17 insertions, 15 deletions

diff --git a/sys/ufs/ufs/ufs_lookup.c b/sys/ufs/ufs/ufs_lookup.c
index da752a7..791d28a 100644
--- a/sys/ufs/ufs/ufs_lookup.c
+++ b/sys/ufs/ufs/ufs_lookup.c
@@ -78,7 +78,7 @@ SYSCTL_INT(_debug, OID_AUTO, dircheck, CTLFLAG_RW, &dirchk, 0, "");
 #define OFSFMT(vp)	((vp)->v_mount->mnt_maxsymlinklen <= 0)
 
 static int ufs_lookup_(struct vnode *, struct vnode **, struct componentname *,
-    ino_t);
+    ino_t *);
 
 /*
  * Convert a component of a pathname into a pointer to a locked inode.
@@ -134,12 +134,12 @@ ufs_lookup(ap)
 	} */ *ap;
 {
 
-	return (ufs_lookup_(ap->a_dvp, ap->a_vpp, ap->a_cnp, 0));
+	return (ufs_lookup_(ap->a_dvp, ap->a_vpp, ap->a_cnp, NULL));
 }
 
 static int
 ufs_lookup_(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
-    ino_t dd_ino)
+    ino_t *dd_ino)
 {
 	struct inode *dp;		/* inode for directory being searched */
 	struct buf *bp;			/* a buffer of directory entries */
@@ -163,15 +163,9 @@ ufs_lookup_(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
 	struct ucred *cred = cnp->cn_cred;
 	int flags = cnp->cn_flags;
 	int nameiop = cnp->cn_nameiop;
-	ino_t ino;
+	ino_t ino, ino1;
 	int ltype;
 
-	bp = NULL;
-	slotoffset = -1;
-/*
- *  XXX there was a soft-update diff about this I couldn't merge.
- * I think this was the equiv.
- */
 	if (vpp != NULL)
 		*vpp = NULL;
 
@@ -185,6 +179,12 @@ ufs_lookup_(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
 	 */
 	vnode_create_vobject(vdp, DIP(dp, i_size), cnp->cn_thread);
 
+	bmask = VFSTOUFS(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
+
+restart:
+	bp = NULL;
+	slotoffset = -1;
+
 	/*
 	 * We now have a segment name to search for, and a directory to search.
 	 *
@@ -202,7 +202,6 @@ ufs_lookup_(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
 		slotstatus = NONE;
 		slotneeded = DIRECTSIZ(cnp->cn_namelen);
 	}
-	bmask = VFSTOUFS(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
 
 #ifdef UFS_DIRHASH
 	/*
@@ -487,9 +486,8 @@ found:
 	if ((flags & ISLASTCN) && nameiop == LOOKUP)
 		dp->i_diroff = i_offset &~ (DIRBLKSIZ - 1);
 
-	if (dd_ino != 0) {
-		if (ino != dd_ino)
-			return (ENOENT);
+	if (dd_ino != NULL) {
+		*dd_ino = ino;
 		return (0);
 	}
 
@@ -600,11 +598,15 @@ found:
 		 * to the inode we looked up before vdp lock was
 		 * dropped.
 		 */
-		error = ufs_lookup_(pdp, NULL, cnp, ino);
+		error = ufs_lookup_(pdp, NULL, cnp, &ino1);
 		if (error) {
 			vput(tdp);
 			return (error);
 		}
+		if (ino1 != ino) {
+			vput(tdp);
+			goto restart;
+		}
 
 		*vpp = tdp;
 	} else if (dp->i_number == ino) {