4 files changed, 63 insertions, 14 deletions

diff --git a/sys/fs/nullfs/null.h b/sys/fs/nullfs/null.h
index 0878e559329d..4f37020d6da5 100644
--- a/sys/fs/nullfs/null.h
+++ b/sys/fs/nullfs/null.h
@@ -34,9 +34,15 @@
  * $FreeBSD$
  */
 
+#ifndef	FS_NULL_H
+#define	FS_NULL_H
+
+#define	NULLM_CACHE	0x0001
+
 struct null_mount {
 	struct mount	*nullm_vfs;
 	struct vnode	*nullm_rootvp;	/* Reference to root null_node */
+	uint64_t	nullm_flags;
 };
 
 #ifdef _KERNEL
@@ -80,3 +86,5 @@ MALLOC_DECLARE(M_NULLFSNODE);
 #endif /* NULLFS_DEBUG */
 
 #endif /* _KERNEL */
+
+#endif
diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
index 884d9b08e03d..ad29b61b43dc 100644
--- a/sys/fs/nullfs/null_subr.c
+++ b/sys/fs/nullfs/null_subr.c
@@ -224,6 +224,9 @@ null_nodeget(mp, lowervp, vpp)
 	 * provide ready to use vnode.
 	 */
 	if (VOP_ISLOCKED(lowervp) != LK_EXCLUSIVE) {
+		KASSERT((MOUNTTONULLMOUNT(mp)->nullm_flags & NULLM_CACHE) != 0,
+		    ("lowervp %p is not excl locked and cache is disabled",
+		    lowervp));
 		vn_lock(lowervp, LK_UPGRADE | LK_RETRY);
 		if ((lowervp->v_iflag & VI_DOOMED) != 0) {
 			vput(lowervp);
diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index 9094fd7673a1..e7ed8756f7b2 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -67,6 +67,15 @@ static vfs_vget_t	nullfs_vget;
 static vfs_extattrctl_t	nullfs_extattrctl;
 static vfs_reclaim_lowervp_t nullfs_reclaim_lowervp;
 
+/* Mount options that we support. */
+static const char *nullfs_opts[] = {
+	"cache",
+	"export",
+	"from",
+	"target",
+	NULL
+};
+
 /*
  * Mount null layer
  */
@@ -86,9 +95,11 @@ nullfs_mount(struct mount *mp)
 
 	if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS))
 		return (EPERM);
-
 	if (mp->mnt_flag & MNT_ROOTFS)
 		return (EOPNOTSUPP);
+	if (vfs_filteropt(mp->mnt_optnew, nullfs_opts))
+		return (EINVAL);
+
 	/*
 	 * Update is a no-op
 	 */
@@ -149,7 +160,7 @@ nullfs_mount(struct mount *mp)
 	}
 
 	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
-	    M_NULLFSMNT, M_WAITOK);
+	    M_NULLFSMNT, M_WAITOK | M_ZERO);
 
 	/*
 	 * Save reference to underlying FS
@@ -187,17 +198,27 @@ nullfs_mount(struct mount *mp)
 		mp->mnt_flag |= MNT_LOCAL;
 		MNT_IUNLOCK(mp);
 	}
+
+	xmp->nullm_flags |= NULLM_CACHE;
+	if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0)
+		xmp->nullm_flags &= ~NULLM_CACHE;
+
 	MNT_ILOCK(mp);
-	mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
-	    (MNTK_MPSAFE | MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED |
-	    MNTK_EXTENDED_SHARED);
+	if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
+		mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
+		    (MNTK_MPSAFE | MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED |
+		    MNTK_EXTENDED_SHARED);
+	}
 	mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT;
 	MNT_IUNLOCK(mp);
 	mp->mnt_data =  xmp;
 	vfs_getnewfsid(mp);
-	MNT_ILOCK(xmp->nullm_vfs);
-	TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, mnt_upper_link);
-	MNT_IUNLOCK(xmp->nullm_vfs);
+	if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
+		MNT_ILOCK(xmp->nullm_vfs);
+		TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp,
+		    mnt_upper_link);
+		MNT_IUNLOCK(xmp->nullm_vfs);
+	}
 
 	vfs_mountedfrom(mp, target);
 
@@ -235,13 +256,15 @@ nullfs_unmount(mp, mntflags)
 	 */
 	mntdata = mp->mnt_data;
 	ump = mntdata->nullm_vfs;
-	MNT_ILOCK(ump);
-	while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) {
-		ump->mnt_kern_flag |= MNTK_VGONE_WAITER;
-		msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0);
+	if ((mntdata->nullm_flags & NULLM_CACHE) != 0) {
+		MNT_ILOCK(ump);
+		while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) {
+			ump->mnt_kern_flag |= MNTK_VGONE_WAITER;
+			msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0);
+		}
+		TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link);
+		MNT_IUNLOCK(ump);
 	}
-	TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link);
-	MNT_IUNLOCK(ump);
 	mp->mnt_data = NULL;
 	free(mntdata, M_NULLFSMNT);
 	return (0);
diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
index 9e58c143f138..96df2f6028d7 100644
--- a/sys/fs/nullfs/null_vnops.c
+++ b/sys/fs/nullfs/null_vnops.c
@@ -692,7 +692,22 @@ null_unlock(struct vop_unlock_args *ap)
 static int
 null_inactive(struct vop_inactive_args *ap __unused)
 {
+	struct vnode *vp;
+	struct mount *mp;
+	struct null_mount *xmp;
 
+	vp = ap->a_vp;
+	mp = vp->v_mount;
+	xmp = MOUNTTONULLMOUNT(mp);
+	if ((xmp->nullm_flags & NULLM_CACHE) == 0) {
+		/*
+		 * If this is the last reference and caching of the
+		 * nullfs vnodes is not enabled, then free up the
+		 * vnode so as not to tie up the lower vnodes.
+		 */
+		vp->v_object = NULL;
+		vrecycle(vp, curthread);
+	}
 	return (0);
 }