Add a flags parameter to VFS_VGET to pass through the desired

locking flags when acquiring a vnode. The immediate purpose is
to allow polling lock requests (LK_NOWAIT) needed by soft updates
to avoid deadlock when enlisting other processes to help with
the background cleanup. For the future it will allow the use of
shared locks for read access to vnodes. This change touches a
lot of files as it affects most filesystems within the system.
It has been well tested on FFS, loopback, and CD-ROM filesystems.
only lightly on the others, so if you find a problem there, please
let me (mckusick@mckusick.com) know.

1 files changed, 12 insertions, 14 deletions

diff --git a/sys/fs/hpfs/hpfs_vnops.c b/sys/fs/hpfs/hpfs_vnops.c
index e3ed555..7b4d731 100644
--- a/sys/fs/hpfs/hpfs_vnops.c
+++ b/sys/fs/hpfs/hpfs_vnops.c
@@ -1096,21 +1096,18 @@ hpfs_lookup(ap)
 		dprintf(("hpfs_lookup(0x%x,...): .. faked (0x%x)\n",
 			dhp->h_no, dhp->h_fn.fn_parent));
 
-		VOP_UNLOCK(dvp,0,cnp->cn_thread);
-
-		error = VFS_VGET(hpmp->hpm_mp,
-				 dhp->h_fn.fn_parent, ap->a_vpp); 
-		if(error) {
+		if (VFS_VGET(hpmp->hpm_mp, dhp->h_fn.fn_parent,
+		    LK_NOWAIT | LK_EXCLUSIVE, ap->a_vpp)) {
+			VOP_UNLOCK(dvp,0,cnp->cn_thread);
+			error = VFS_VGET(hpmp->hpm_mp,
+				 dhp->h_fn.fn_parent, LK_EXCLUSIVE, ap->a_vpp); 
 			VOP_LOCK(dvp, 0, cnp->cn_thread);
-			return(error);
-		}
-
-		if( lockparent && (flags & ISLASTCN) && 
-		    (error = VOP_LOCK(dvp, 0, cnp->cn_thread)) ) {
-			vput( *(ap->a_vpp) );
-			return (error);
+			if(error)
+				return(error);
 		}
-		return (error);
+		if (!lockparent || !(flags & ISLASTCN))
+			VOP_UNLOCK(dvp,0,cnp->cn_thread);
+		return (0);
 	} else {
 		struct buf *bp;
 		struct hpfsdirent *dep;
@@ -1148,7 +1145,8 @@ hpfs_lookup(ap)
 			return (0);
 		}
 
-		error = VFS_VGET(hpmp->hpm_mp, dep->de_fnode, ap->a_vpp);
+		error = VFS_VGET(hpmp->hpm_mp, dep->de_fnode, LK_EXCLUSIVE,
+				 ap->a_vpp);
 		if (error) {
 			printf("hpfs_lookup: VFS_VGET FAILED %d\n", error);
 			brelse(bp);