--- //depot/projects/smpng/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c	2009/01/28 22:38:17
+++ //depot/user/jhb/lock/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c	2009/01/28 23:05:44
@@ -153,7 +153,6 @@
 	zp->z_vnode = vp;
 	vp->v_data = (caddr_t)zp;
 	VN_LOCK_AREC(vp);
-	VN_LOCK_ASHARE(vp);
 
 	list_link_init(&zp->z_link_node);
 
@@ -610,6 +609,8 @@
 		vp->v_op = &zfs_fifoops;
 		break;
 	}
+	if (vp->v_type != VFIFO)
+		VN_LOCK_ASHARE(vp);
 
 	mutex_enter(&zfsvfs->z_znodes_lock);
 	list_insert_tail(&zfsvfs->z_all_znodes, zp);
@@ -1491,6 +1492,7 @@
 
 	vp = ZTOV(rootzp);
 	vp->v_type = VDIR;
+	VN_LOCK_ASHARE(vp);
 
 	bzero(&zfsvfs, sizeof (zfsvfs_t));
 
--- //depot/projects/smpng/sys/dev/md/md.c	2009/02/23 18:46:27
+++ //depot/user/jhb/lock/dev/md/md.c	2009/02/23 19:02:01
@@ -924,12 +924,20 @@
 		return (error);
 	vfslocked = NDHASGIANT(&nd);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
-	if (nd.ni_vp->v_type != VREG ||
-	    (error = VOP_GETATTR(nd.ni_vp, &vattr, td->td_ucred))) {
-		VOP_UNLOCK(nd.ni_vp, 0);
-		(void)vn_close(nd.ni_vp, flags, td->td_ucred, td);
-		VFS_UNLOCK_GIANT(vfslocked);
-		return (error ? error : EINVAL);
+	if (nd.ni_vp->v_type != VREG) {
+		error = EINVAL;
+		goto bad;
+	}	
+	error = VOP_GETATTR(nd.ni_vp, &vattr, td->td_ucred);
+	if (error != 0)
+		goto bad;
+	if (VOP_ISLOCKED(nd.ni_vp) != LK_EXCLUSIVE) {
+		vn_lock(nd.ni_vp, LK_UPGRADE | LK_RETRY);
+		if (nd.ni_vp->v_iflag & VI_DOOMED) {
+			/* Forced unmount. */
+			error = EBADF;
+			goto bad;
+		}
 	}
 	nd.ni_vp->v_vflag |= VV_MD;
 	VOP_UNLOCK(nd.ni_vp, 0);
@@ -948,13 +956,15 @@
 		sc->vnode = NULL;
 		vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
 		nd.ni_vp->v_vflag &= ~VV_MD;
-		VOP_UNLOCK(nd.ni_vp, 0);
-		(void)vn_close(nd.ni_vp, flags, td->td_ucred, td);
-		VFS_UNLOCK_GIANT(vfslocked);
-		return (error);
+		goto bad;
 	}
 	VFS_UNLOCK_GIANT(vfslocked);
 	return (0);
+bad:
+	VOP_UNLOCK(nd.ni_vp, 0);
+	(void)vn_close(nd.ni_vp, flags, td->td_ucred, td);
+	VFS_UNLOCK_GIANT(vfslocked);
+	return (error);
 }
 
 static int
--- //depot/projects/smpng/sys/fs/cd9660/cd9660_vfsops.c	2009/02/13 18:22:54
+++ //depot/user/jhb/lock/fs/cd9660/cd9660_vfsops.c	2009/02/13 20:21:57
@@ -371,7 +372,8 @@
 	mp->mnt_maxsymlinklen = 0;
 	MNT_ILOCK(mp);
 	mp->mnt_flag |= MNT_LOCAL;
-	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED;
+	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED |
+	    MNTK_EXTENDED_SHARED;
 	MNT_IUNLOCK(mp);
 	isomp->im_mountp = mp;
 	isomp->im_dev = dev;
--- //depot/projects/smpng/sys/fs/udf/udf_vfsops.c	2009/02/27 15:49:22
+++ //depot/user/jhb/lock/fs/udf/udf_vfsops.c	2009/02/27 16:32:01
@@ -353,7 +354,8 @@
 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
 	MNT_ILOCK(mp);
 	mp->mnt_flag |= MNT_LOCAL;
-	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED;
+	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED |
+	    MNTK_EXTENDED_SHARED;
 	MNT_IUNLOCK(mp);
 	udfmp->im_mountp = mp;
 	udfmp->im_dev = dev;
--- //depot/projects/smpng/sys/kern/vfs_lookup.c	2009/01/15 22:41:24
+++ //depot/user/jhb/lock/kern/vfs_lookup.c	2009/01/16 13:17:12
@@ -353,6 +353,41 @@
 	return (lkflags);
 }
 
+static __inline int
+needs_exclusive_leaf(struct mount *mp, int flags)
+{
+
+	/*
+	 * Intermediate nodes can use shared locks, we only need to
+	 * force an exclusive lock for leaf nodes.
+	 */
+	if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF))
+		return (0);
+
+	/* Always use exclusive locks if LOCKSHARED isn't set. */
+	if (!(flags & LOCKSHARED))
+		return (1);
+
+	/*
+	 * For lookups during open(), if the mount point supports
+	 * extended shared operations, then use a shared lock for the
+	 * leaf node, otherwise use an exclusive lock.
+	 */
+	if (flags & ISOPEN) {
+		if (mp != NULL &&
+		    (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED))
+			return (0);
+		else
+			return (1);
+	}
+
+	/*
+	 * Lookup requests outside of open() that specify LOCKSHARED
+	 * only need a shared lock on the leaf vnode.
+	 */
+	return (1);
+}
+
 /*
  * Search a pathname.
  * This is a very central and rather complicated routine.
@@ -610,8 +645,7 @@
 	 * If we're looking up the last component and we need an exclusive
 	 * lock, adjust our lkflags.
 	 */
-	if ((cnp->cn_flags & (ISLASTCN|LOCKSHARED|LOCKLEAF)) ==
-	    (ISLASTCN|LOCKLEAF))
+	if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags))
 		cnp->cn_lkflags = LK_EXCLUSIVE;
 #ifdef NAMEI_DIAGNOSTIC
 	vprint("lookup in", dp);
@@ -811,8 +845,8 @@
 	 * Because of lookup_shared we may have the vnode shared locked, but
 	 * the caller may want it to be exclusively locked.
 	 */
-	if ((cnp->cn_flags & (ISLASTCN | LOCKSHARED | LOCKLEAF)) ==
-	    (ISLASTCN | LOCKLEAF) && VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
+	if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) &&
+	    VOP_ISLOCKED(dp) != LK_EXCLUSIVE) {
 		vn_lock(dp, LK_UPGRADE | LK_RETRY);
 		if (dp->v_iflag & VI_DOOMED) {
 			error = ENOENT;
--- //depot/projects/smpng/sys/kern/vfs_vnops.c	2009/01/21 21:09:25
+++ //depot/user/jhb/lock/kern/vfs_vnops.c	2009/01/21 21:15:47
@@ -188,6 +188,8 @@
 		ndp->ni_cnd.cn_flags = ISOPEN |
 		    ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) |
 		    LOCKLEAF | MPSAFE | AUDITVNODE1;
+		if (!(fmode & FWRITE))
+			ndp->ni_cnd.cn_flags |= LOCKSHARED;
 		if ((error = namei(ndp)) != 0)
 			return (error);
 		if (!mpsafe)
@@ -240,7 +242,7 @@
 	if (fmode & FWRITE)
 		vp->v_writecount++;
 	*flagp = fmode;
-	ASSERT_VOP_ELOCKED(vp, "vn_open_cred");
+	ASSERT_VOP_LOCKED(vp, "vn_open_cred");
 	if (!mpsafe)
 		VFS_UNLOCK_GIANT(vfslocked);
 	return (0);
@@ -285,12 +287,18 @@
 	struct thread *td;
 {
 	struct mount *mp;
-	int error;
+	int error, lock_flags;
+
+	if (!(flags & FWRITE) && vp->v_mount != NULL &&
+	    vp->v_mount->mnt_kern_flag & MNTK_EXTENDED_SHARED)
+		lock_flags = LK_SHARED;
+	else
+		lock_flags = LK_EXCLUSIVE;
 
 	VFS_ASSERT_GIANT(vp->v_mount);
 
 	vn_start_write(vp, &mp, V_WAIT);
-	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+	vn_lock(vp, lock_flags | LK_RETRY);
 	if (flags & FWRITE) {
 		VNASSERT(vp->v_writecount > 0, vp, 
 		    ("vn_close: negative writecount"));
--- //depot/projects/smpng/sys/kern/vnode_if.src	2009/01/21 21:09:25
+++ //depot/user/jhb/lock/kern/vnode_if.src	2009/01/21 21:15:47
@@ -133,7 +133,7 @@
 };
 
 
-%% close	vp	E E E
+%% close	vp	L L L
 
 vop_close {
 	IN struct vnode *vp;
--- //depot/projects/smpng/sys/sys/mount.h	2009/02/09 16:14:58
+++ //depot/user/jhb/lock/sys/mount.h	2009/02/09 17:56:53
@@ -318,14 +318,15 @@
 #define MNTK_NOINSMNTQ	0x00000008	/* insmntque is not allowed */
 #define	MNTK_DRAINING	0x00000010	/* lock draining is happening */
 #define	MNTK_REFEXPIRE	0x00000020	/* refcount expiring is happening */
+#define MNTK_EXTENDED_SHARED	0x00000040 /* Allow shared locking for more ops */
 #define MNTK_UNMOUNT	0x01000000	/* unmount in progress */
 #define	MNTK_MWAIT	0x02000000	/* waiting for unmount to finish */
 #define	MNTK_SUSPEND	0x08000000	/* request write suspension */
 #define	MNTK_SUSPEND2	0x04000000	/* block secondary writes */
 #define	MNTK_SUSPENDED	0x10000000	/* write operations are suspended */
 #define	MNTK_MPSAFE	0x20000000	/* Filesystem is MPSAFE. */
+#define MNTK_LOOKUP_SHARED	0x40000000 /* FS supports shared lock lookups */
 #define	MNTK_NOKNOTE	0x80000000	/* Don't send KNOTEs from VOP hooks */
-#define MNTK_LOOKUP_SHARED	0x40000000 /* FS supports shared lock lookups */
 
 /*
  * Sysctl CTL_VFS definitions.
--- //depot/projects/smpng/sys/ufs/ffs/ffs_vfsops.c	2009/02/27 15:49:22
+++ //depot/user/jhb/lock/ufs/ffs/ffs_vfsops.c	2009/02/27 16:32:01
@@ -883,7 +883,8 @@
 	 * Initialize filesystem stat information in mount struct.
 	 */
 	MNT_ILOCK(mp);
-	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED;
+	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED |
+	    MNTK_EXTENDED_SHARED;
 	MNT_IUNLOCK(mp);
 #ifdef UFS_EXTATTR
 #ifdef UFS_EXTATTR_AUTOSTART
@@ -1440,10 +1441,9 @@
 		return (error);
 	}
 	/*
-	 * FFS supports recursive and shared locking.
+	 * FFS supports recursive locking.
 	 */
 	VN_LOCK_AREC(vp);
-	VN_LOCK_ASHARE(vp);
 	vp->v_data = ip;
 	vp->v_bufobj.bo_bsize = fs->fs_bsize;
 	ip->i_vnode = vp;
@@ -1516,6 +1516,10 @@
 	/*
 	 * Finish inode initialization.
 	 */
+	if (vp->v_type != VFIFO) {
+		/* FFS supports shared locking for all files except fifos. */
+		VN_LOCK_ASHARE(vp);
+	}
 
 	/*
 	 * Set up a generation number for this inode if it does not