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, 23 insertions, 7 deletions

diff --git a/sys/isofs/cd9660/cd9660_vfsops.c b/sys/isofs/cd9660/cd9660_vfsops.c
index 1e3719d..60a7b38 100644
--- a/sys/isofs/cd9660/cd9660_vfsops.c
+++ b/sys/isofs/cd9660/cd9660_vfsops.c
@@ -69,7 +69,7 @@ static int cd9660_mount __P((struct mount *,
 static int cd9660_unmount __P((struct mount *, int, struct thread *));
 static int cd9660_root __P((struct mount *, struct vnode **));
 static int cd9660_statfs __P((struct mount *, struct statfs *, struct thread *));
-static int cd9660_vget __P((struct mount *, ino_t, struct vnode **));
+static int cd9660_vget __P((struct mount *, ino_t, int, struct vnode **));
 static int cd9660_fhtovp __P((struct mount *, struct fid *, struct vnode **));
 static int cd9660_vptofh __P((struct vnode *, struct fid *));
 
@@ -578,7 +578,7 @@ cd9660_root(mp, vpp)
 	 * With RRIP we must use the `.' entry of the root directory.
 	 * Simply tell vget, that it's a relocated directory.
 	 */
-	return (cd9660_vget_internal(mp, ino, vpp,
+	return (cd9660_vget_internal(mp, ino, LK_EXCLUSIVE, vpp,
 	    imp->iso_ftype == ISO_FTYPE_RRIP, dp));
 }
 
@@ -644,7 +644,7 @@ cd9660_fhtovp(mp, fhp, vpp)
 	       ifhp->ifid_ino, ifhp->ifid_start);
 #endif
 	
-	if ((error = VFS_VGET(mp, ifhp->ifid_ino, &nvp)) != 0) {
+	if ((error = VFS_VGET(mp, ifhp->ifid_ino, LK_EXCLUSIVE, &nvp)) != 0) {
 		*vpp = NULLVP;
 		return (error);
 	}
@@ -659,9 +659,10 @@ cd9660_fhtovp(mp, fhp, vpp)
 }
 
 int
-cd9660_vget(mp, ino, vpp)
+cd9660_vget(mp, ino, flags, vpp)
 	struct mount *mp;
 	ino_t ino;
+	int flags;
 	struct vnode **vpp;
 {
 
@@ -671,7 +672,7 @@ cd9660_vget(mp, ino, vpp)
 	 * and force the extra read, but I don't want to think about fixing
 	 * that right now.
 	 */
-	return (cd9660_vget_internal(mp, ino, vpp,
+	return (cd9660_vget_internal(mp, ino, flags, vpp,
 #if 0
 	    VFSTOISOFS(mp)->iso_ftype == ISO_FTYPE_RRIP,
 #else
@@ -681,9 +682,10 @@ cd9660_vget(mp, ino, vpp)
 }
 
 int
-cd9660_vget_internal(mp, ino, vpp, relocated, isodir)
+cd9660_vget_internal(mp, ino, flags, vpp, relocated, isodir)
 	struct mount *mp;
 	ino_t ino;
+	int flags;
 	struct vnode **vpp;
 	int relocated;
 	struct iso_directory_record *isodir;
@@ -697,7 +699,9 @@ cd9660_vget_internal(mp, ino, vpp, relocated, isodir)
 
 	imp = VFSTOISOFS(mp);
 	dev = imp->im_dev;
-	if ((*vpp = cd9660_ihashget(dev, ino)) != NULLVP)
+	if ((error = cd9660_ihashget(dev, ino, flags, vpp)) != 0)
+		return (error);
+	if (*vpp != NULL)
 		return (0);
 
 	/* Allocate a new vnode/iso_node. */
@@ -718,6 +722,18 @@ cd9660_vget_internal(mp, ino, vpp, relocated, isodir)
 	ip->i_number = ino;
 
 	/*
+	 * Check to be sure that it did not show up. We have to put it
+	 * on the hash chain as the cleanup from vput expects to find 
+	 * it there.
+	 */
+	if ((error = cd9660_ihashget(dev, ino, flags, vpp)) != 0 ||
+	    *vpp != NULL) {
+		cd9660_ihashins(ip);
+		vput(vp);
+		return (error);
+	}
+
+	/*
 	 * Put it onto its hash chain and lock it so that other requests for
 	 * this inode will block if they arrive while we are sleeping waiting
 	 * for old data structures to be purged or for the contents of the