Reorganize how the root vnode is fetched so that it doesn't always

go through VFS_ROOT() and allow to fetch it without locking it.
This allows us to call the cache flush operations also for the root
vnode and most notably fixes e.g. a "No such file or directory"
for a psshfs root directory ls -l when a file was locally deleted
and remotely re-created.

Also fix some sloppy programming in root node fetch (mostly cosmetic).

sys/fs/puffs/puffs_subr.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: puffs_subr.c,v 1.32 2007/06/06 01:55:00 pooka Exp $	*/
+/*	$NetBSD: puffs_subr.c,v 1.33 2007/06/21 14:11:34 pooka Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006  Antti Kantee.  All Rights Reserved.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: puffs_subr.c,v 1.32 2007/06/06 01:55:00 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: puffs_subr.c,v 1.33 2007/06/21 14:11:34 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/conf.h>
@@ -335,6 +335,59 @@ puffs_cookie2pnode(struct puffs_mount *pmp, void *cookie)
 	return pnode;
 }
 
+/*
+ * Make sure root vnode exists and reference it.  Does NOT lock.
+ */
+int
+puffs_makeroot(struct puffs_mount *pmp)
+{
+	struct vnode *vp;
+	int rv;
+
+	/*
+	 * pmp_lock must be held if vref()'ing or vrele()'ing the
+	 * root vnode.  the latter is controlled by puffs_inactive().
+	 *
+	 * pmp_root is set here and cleared in puffs_reclaim().
+	 */
+ retry:
+	mutex_enter(&pmp->pmp_lock);
+	vp = pmp->pmp_root;
+	if (vp) {
+		simple_lock(&vp->v_interlock);
+		mutex_exit(&pmp->pmp_lock);
+		if (vget(vp, LK_INTERLOCK) == 0)
+			return 0;
+	} else
+		mutex_exit(&pmp->pmp_lock);
+
+	/*
+	 * So, didn't have the magic root vnode available.
+	 * No matter, grab another an stuff it with the cookie.
+	 */
+	if ((rv = puffs_getvnode(pmp->pmp_mp, pmp->pmp_root_cookie,
+	    pmp->pmp_root_vtype, pmp->pmp_root_vsize, pmp->pmp_root_rdev, &vp)))
+		return rv;
+
+	/*
+	 * Someone magically managed to race us into puffs_getvnode?
+	 * Put our previous new vnode back and retry.
+	 */
+	mutex_enter(&pmp->pmp_lock);
+	if (pmp->pmp_root) {
+		mutex_exit(&pmp->pmp_lock);
+		puffs_putvnode(vp);
+		goto retry;
+	} 
+
+	/* store cache */
+	vp->v_flag = VROOT;
+	pmp->pmp_root = vp;
+	mutex_exit(&pmp->pmp_lock);
+
+	return 0;
+}
+
 /*
  * Locate the in-kernel vnode based on the cookie received given
  * from userspace.  Returns a vnode, if found, NULL otherwise.
@@ -351,17 +404,16 @@ puffs_pnode2vnode(struct puffs_mount *pmp, void *cookie, int lock)
 	int vgetflags;
 
 	/*
-	 * If we're trying to get the root vnode, return it through
+	 * Handle root in a special manner, since we want to make sure
-	 * puffs_root() to get all the right things set.  Lock must
+	 * pmp_root is properly set.
-	 * be set, since VFS_ROOT() always locks the returned vnode.
 	 */
 	if (cookie == pmp->pmp_root_cookie) {
-		if (!lock)
+		if (puffs_makeroot(pmp))
-			return NULL;
-		if (VFS_ROOT(pmp->pmp_mp, &vp))
 			return NULL;
+		if (lock)
+			vn_lock(pmp->pmp_root, LK_EXCLUSIVE | LK_RETRY);
 
-		return vp;
+		return pmp->pmp_root;
 	}
 
 	vgetflags = LK_INTERLOCK;

sys/fs/puffs/puffs_sys.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: puffs_sys.h,v 1.39 2007/06/06 01:55:00 pooka Exp $	*/
+/*	$NetBSD: puffs_sys.h,v 1.40 2007/06/21 14:11:34 pooka Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006  Antti Kantee.  All Rights Reserved.
@@ -227,6 +227,7 @@ void	puffs_putvnode(struct vnode *);
 void	puffs_releasenode(struct puffs_node *);
 void	puffs_referencenode(struct puffs_node *);
 
+int	puffs_makeroot(struct puffs_mount *);
 struct vnode *puffs_pnode2vnode(struct puffs_mount *, void *, int);
 void	puffs_makecn(struct puffs_kcn *, const struct componentname *);
 void	puffs_credcvt(struct puffs_cred *, kauth_cred_t);

sys/fs/puffs/puffs_vfsops.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: puffs_vfsops.c,v 1.43 2007/06/06 01:55:00 pooka Exp $	*/
+/*	$NetBSD: puffs_vfsops.c,v 1.44 2007/06/21 14:11:34 pooka Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006  Antti Kantee.  All Rights Reserved.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: puffs_vfsops.c,v 1.43 2007/06/06 01:55:00 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: puffs_vfsops.c,v 1.44 2007/06/21 14:11:34 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/mount.h>
@@ -340,61 +340,16 @@ int
 puffs_root(struct mount *mp, struct vnode **vpp)
 {
 	struct puffs_mount *pmp;
-	struct puffs_node *pn;
+	int rv;
-	struct vnode *vp;
 
 	pmp = MPTOPUFFSMP(mp);
+	rv = puffs_makeroot(pmp);
+	if (rv)
+		return rv;
 
-	/*
-	 * pmp_lock must be held if vref()'ing or vrele()'ing the
-	 * root vnode.  the latter is controlled by puffs_inactive().
-	 */
-	mutex_enter(&pmp->pmp_lock);
-	vp = pmp->pmp_root;
-	if (vp) {
-		simple_lock(&vp->v_interlock);
-		mutex_exit(&pmp->pmp_lock);
-		pn = VPTOPP(vp);
-		if (vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK))
-			goto grabnew;
-		*vpp = vp;
-		return 0;
-	} else
-		mutex_exit(&pmp->pmp_lock);
-
-	/* XXX: this is wrong, so FIXME */
- grabnew:
-
-	/*
-	 * So, didn't have the magic root vnode available.
-	 * No matter, grab another an stuff it with the cookie.
-	 */
-	if (puffs_getvnode(mp, pmp->pmp_root_cookie, pmp->pmp_root_vtype,
-	    pmp->pmp_root_vsize, pmp->pmp_root_rdev, &vp))
-		panic("sloppy programming");
-
-	mutex_enter(&pmp->pmp_lock);
-	/*
-	 * check if by mysterious force someone else created a root
-	 * vnode while we were executing.
-	 */
-	if (pmp->pmp_root) {
-		vref(pmp->pmp_root);
-		mutex_exit(&pmp->pmp_lock);
-		puffs_putvnode(vp);
 	vn_lock(pmp->pmp_root, LK_EXCLUSIVE | LK_RETRY);
 	*vpp = pmp->pmp_root;
-		return 0;
-	} 
 
-	/* store cache */
-	vp->v_flag = VROOT;
-	pmp->pmp_root = vp;
-	mutex_exit(&pmp->pmp_lock);
-
-	vn_lock(pmp->pmp_root, LK_EXCLUSIVE | LK_RETRY);
-
-	*vpp = vp;
 	return 0;
 }