- cache dp->i_offset in the local 'i_offset' variable for use in loop

   indexes so directory lookup becomes shared lock safe.  In the modifying
   cases an exclusive lock is held here so the commit routine may
   rely on the state of i_offset.
 - Similarly handle i_diroff by fetching at the start and setting only once
   the operation is complete.  Without the exclusive lock these are only
   considered hints.
 - Assert that an exclusive lock is held when we're preparing for a commit
   routine.
 - Honor the lock type request from lookup instead of always using exclusive
   locking.

Tested by:	pho, kris

1 files changed, 48 insertions, 29 deletions

diff --git a/sys/ufs/ufs/ufs_lookup.c b/sys/ufs/ufs/ufs_lookup.c
index ea1d794..4637865 100644
--- a/sys/ufs/ufs/ufs_lookup.c
+++ b/sys/ufs/ufs/ufs_lookup.c
@@ -137,6 +137,8 @@ ufs_lookup(ap)
 	int entryoffsetinblock;		/* offset of ep in bp's buffer */
 	enum {NONE, COMPACT, FOUND} slotstatus;
 	doff_t slotoffset;		/* offset of area with free space */
+	doff_t i_diroff;		/* cached i_diroff value. */
+	doff_t i_offset;		/* cached i_offset value. */
 	int slotsize;			/* size of area at slotoffset */
 	int slotfreespace;		/* amount of space free in slot */
 	int slotneeded;			/* size of the entry we're seeking */
@@ -154,6 +156,7 @@ ufs_lookup(ap)
 	int flags = cnp->cn_flags;
 	int nameiop = cnp->cn_nameiop;
 	ino_t saved_ino;
+	int ltype;
 
 	bp = NULL;
 	slotoffset = -1;
@@ -173,6 +176,7 @@ ufs_lookup(ap)
 	 * we watch for a place to put the new file in
 	 * case it doesn't already exist.
 	 */
+	i_diroff = dp->i_diroff;
 	slotstatus = FOUND;
 	slotfreespace = slotsize = slotneeded = 0;
 	if ((nameiop == CREATE || nameiop == RENAME) &&
@@ -206,13 +210,13 @@ ufs_lookup(ap)
 		numdirpasses = 1;
 		entryoffsetinblock = 0; /* silence compiler warning */
 		switch (ufsdirhash_lookup(dp, cnp->cn_nameptr, cnp->cn_namelen,
-		    &dp->i_offset, &bp, nameiop == DELETE ? &prevoff : NULL)) {
+		    &i_offset, &bp, nameiop == DELETE ? &prevoff : NULL)) {
 		case 0:
 			ep = (struct direct *)((char *)bp->b_data +
-			    (dp->i_offset & bmask));
+			    (i_offset & bmask));
 			goto foundentry;
 		case ENOENT:
-			dp->i_offset = roundup2(dp->i_size, DIRBLKSIZ);
+			i_offset = roundup2(dp->i_size, DIRBLKSIZ);
 			goto notfound;
 		default:
 			/* Something failed; just do a linear search. */
@@ -231,33 +235,32 @@ ufs_lookup(ap)
 	 * profiling time and hence has been removed in the interest
 	 * of simplicity.
 	 */
-	if (nameiop != LOOKUP || dp->i_diroff == 0 ||
-	    dp->i_diroff >= dp->i_size) {
+	if (nameiop != LOOKUP || i_diroff == 0 || i_diroff >= dp->i_size) {
 		entryoffsetinblock = 0;
-		dp->i_offset = 0;
+		i_offset = 0;
 		numdirpasses = 1;
 	} else {
-		dp->i_offset = dp->i_diroff;
-		if ((entryoffsetinblock = dp->i_offset & bmask) &&
-		    (error = UFS_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)))
+		i_offset = i_diroff;
+		if ((entryoffsetinblock = i_offset & bmask) &&
+		    (error = UFS_BLKATOFF(vdp, (off_t)i_offset, NULL, &bp)))
 			return (error);
 		numdirpasses = 2;
 		nchstats.ncs_2passes++;
 	}
-	prevoff = dp->i_offset;
+	prevoff = i_offset;
 	endsearch = roundup2(dp->i_size, DIRBLKSIZ);
 	enduseful = 0;
 
 searchloop:
-	while (dp->i_offset < endsearch) {
+	while (i_offset < endsearch) {
 		/*
 		 * If necessary, get the next directory block.
 		 */
-		if ((dp->i_offset & bmask) == 0) {
+		if ((i_offset & bmask) == 0) {
 			if (bp != NULL)
 				brelse(bp);
 			error =
-			    UFS_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp);
+			    UFS_BLKATOFF(vdp, (off_t)i_offset, NULL, &bp);
 			if (error)
 				return (error);
 			entryoffsetinblock = 0;
@@ -284,9 +287,9 @@ searchloop:
 		    (dirchk && ufs_dirbadentry(vdp, ep, entryoffsetinblock))) {
 			int i;
 
-			ufs_dirbad(dp, dp->i_offset, "mangled entry");
+			ufs_dirbad(dp, i_offset, "mangled entry");
 			i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1));
-			dp->i_offset += i;
+			i_offset += i;
 			entryoffsetinblock += i;
 			continue;
 		}
@@ -305,15 +308,15 @@ searchloop:
 			if (size > 0) {
 				if (size >= slotneeded) {
 					slotstatus = FOUND;
-					slotoffset = dp->i_offset;
+					slotoffset = i_offset;
 					slotsize = ep->d_reclen;
 				} else if (slotstatus == NONE) {
 					slotfreespace += size;
 					if (slotoffset == -1)
-						slotoffset = dp->i_offset;
+						slotoffset = i_offset;
 					if (slotfreespace >= slotneeded) {
 						slotstatus = COMPACT;
-						slotsize = dp->i_offset +
+						slotsize = i_offset +
 						      ep->d_reclen - slotoffset;
 					}
 				}
@@ -347,7 +350,7 @@ foundentry:
 				if (vdp->v_mount->mnt_maxsymlinklen > 0 &&
 				    ep->d_type == DT_WHT) {
 					slotstatus = FOUND;
-					slotoffset = dp->i_offset;
+					slotoffset = i_offset;
 					slotsize = ep->d_reclen;
 					dp->i_reclen = slotsize;
 					enduseful = dp->i_size;
@@ -360,11 +363,11 @@ foundentry:
 				goto found;
 			}
 		}
-		prevoff = dp->i_offset;
-		dp->i_offset += ep->d_reclen;
+		prevoff = i_offset;
+		i_offset += ep->d_reclen;
 		entryoffsetinblock += ep->d_reclen;
 		if (ep->d_ino)
-			enduseful = dp->i_offset;
+			enduseful = i_offset;
 	}
 notfound:
 	/*
@@ -373,10 +376,11 @@ notfound:
 	 */
 	if (numdirpasses == 2) {
 		numdirpasses--;
-		dp->i_offset = 0;
-		endsearch = dp->i_diroff;
+		i_offset = 0;
+		endsearch = i_diroff;
 		goto searchloop;
 	}
+	dp->i_offset = i_offset;
 	if (bp != NULL)
 		brelse(bp);
 	/*
@@ -389,6 +393,7 @@ notfound:
 	      (ap->a_cnp->cn_flags & DOWHITEOUT) &&
 	      (ap->a_cnp->cn_flags & ISWHITEOUT))) &&
 	    (flags & ISLASTCN) && dp->i_effnlink != 0) {
+		ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
 		/*
 		 * Access for write is interpreted as allowing
 		 * creation of files in the directory.
@@ -452,9 +457,9 @@ found:
 	 * Check that directory length properly reflects presence
 	 * of this entry.
 	 */
-	if (dp->i_offset + DIRSIZ(OFSFMT(vdp), ep) > dp->i_size) {
-		ufs_dirbad(dp, dp->i_offset, "i_size too small");
-		dp->i_size = dp->i_offset + DIRSIZ(OFSFMT(vdp), ep);
+	if (i_offset + DIRSIZ(OFSFMT(vdp), ep) > dp->i_size) {
+		ufs_dirbad(dp, i_offset, "i_size too small");
+		dp->i_size = i_offset + DIRSIZ(OFSFMT(vdp), ep);
 		DIP_SET(dp, i_size, dp->i_size);
 		dp->i_flag |= IN_CHANGE | IN_UPDATE;
 	}
@@ -466,13 +471,15 @@ found:
 	 * in the cache as to where the entry was found.
 	 */
 	if ((flags & ISLASTCN) && nameiop == LOOKUP)
-		dp->i_diroff = dp->i_offset &~ (DIRBLKSIZ - 1);
+		dp->i_diroff = i_offset &~ (DIRBLKSIZ - 1);
 
+	dp->i_offset = i_offset;
 	/*
 	 * If deleting, and at end of pathname, return
 	 * parameters which can be used to remove file.
 	 */
 	if (nameiop == DELETE && (flags & ISLASTCN)) {
+		ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
 		/*
 		 * Write access to directory required to delete files.
 		 */
@@ -557,16 +564,28 @@ found:
 	 */
 	pdp = vdp;
 	if (flags & ISDOTDOT) {
+		ltype = VOP_ISLOCKED(pdp);
 		saved_ino = dp->i_ino;
 		VOP_UNLOCK(pdp, 0);	/* race to get the inode */
 		error = VFS_VGET(pdp->v_mount, saved_ino,
 		    cnp->cn_lkflags, &tdp);
-		vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY);
+		vn_lock(pdp, ltype | LK_RETRY);
 		if (error)
 			return (error);
 		*vpp = tdp;
 	} else if (dp->i_number == dp->i_ino) {
 		VREF(vdp);	/* we want ourself, ie "." */
+		/*
+		 * When we lookup "." we still can be asked to lock it
+		 * differently.
+		 */
+		ltype = cnp->cn_lkflags & LK_TYPE_MASK;
+		if (ltype != VOP_ISLOCKED(vdp)) {
+			if (ltype == LK_EXCLUSIVE)
+				vn_lock(vdp, LK_UPGRADE | LK_RETRY);
+			else /* if (ltype == LK_SHARED) */
+				vn_lock(vdp, LK_DOWNGRADE | LK_RETRY);
+		}
 		*vpp = vdp;
 	} else {
 		error = VFS_VGET(pdp->v_mount, dp->i_ino,