From 7ee6b427aee5be9ef1e3f844d49ded50e6309bf2 Mon Sep 17 00:00:00 2001
From: kib <kib@FreeBSD.org>
Date: Sun, 19 Apr 2009 05:34:07 +0000
Subject: [PATCH] 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
---
 sys/ufs/ufs/ufs_lookup.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/sys/ufs/ufs/ufs_lookup.c b/sys/ufs/ufs/ufs_lookup.c
index da752a7716d6..791d28a3900f 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) {