MFC r312428:

Refcount tmpfs nodes and mount structures.

4 files changed, 130 insertions, 44 deletions

diff --git a/sys/fs/tmpfs/tmpfs.h b/sys/fs/tmpfs/tmpfs.h
index fe81d39..8661f42 100644
--- a/sys/fs/tmpfs/tmpfs.h
+++ b/sys/fs/tmpfs/tmpfs.h
@@ -158,9 +158,11 @@ struct tmpfs_node {
 	 * Doubly-linked list entry which links all existing nodes for
 	 * a single file system.  This is provided to ease the removal
 	 * of all nodes during the unmount operation, and to support
-	 * the implementation of VOP_VNTOCNP().
+	 * the implementation of VOP_VNTOCNP().  tn_attached is false
+	 * when the node is removed from list and unlocked.
 	 */
 	LIST_ENTRY(tmpfs_node)	tn_entries;	/* (m) */
+	bool			tn_attached;	/* (m) */
 
 	/*
 	 * The node's type.  Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
@@ -231,6 +233,9 @@ struct tmpfs_node {
 	 */
 	int		tn_vpstate;		/* (i) */
 
+	/* Transient refcounter on this node. */
+	u_int		tn_refcount;		/* (m) + (i) */
+
 	/* misc data field for different tn_type node */
 	union {
 		/* Valid when tn_type == VBLK || tn_type == VCHR. */
@@ -358,6 +363,9 @@ struct tmpfs_mount {
 	/* Number of nodes currently that are in use. */
 	ino_t			tm_nodes_inuse;
 
+	/* Refcounter on this struct tmpfs_mount. */
+	uint64_t		tm_refcount;
+
 	/* maximum representable file size */
 	u_int64_t		tm_maxfilesize;
 
@@ -402,10 +410,14 @@ struct tmpfs_dir_cursor {
  * Prototypes for tmpfs_subr.c.
  */
 
+void	tmpfs_ref_node(struct tmpfs_node *node);
+void	tmpfs_ref_node_locked(struct tmpfs_node *node);
 int	tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype,
 	    uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
 	    char *, dev_t, struct tmpfs_node **);
 void	tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
+bool	tmpfs_free_node_locked(struct tmpfs_mount *, struct tmpfs_node *, bool);
+void	tmpfs_free_tmp(struct tmpfs_mount *);
 int	tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
 	    const char *, u_int, struct tmpfs_dirent **);
 void	tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
diff --git a/sys/fs/tmpfs/tmpfs_subr.c b/sys/fs/tmpfs/tmpfs_subr.c
index 5acb3c0..32091de 100644
--- a/sys/fs/tmpfs/tmpfs_subr.c
+++ b/sys/fs/tmpfs/tmpfs_subr.c
@@ -132,6 +132,26 @@ tmpfs_pages_check_avail(struct tmpfs_mount *tmp, size_t req_pages)
 	return (1);
 }
 
+void
+tmpfs_ref_node(struct tmpfs_node *node)
+{
+
+	TMPFS_NODE_LOCK(node);
+	tmpfs_ref_node_locked(node);
+	TMPFS_NODE_UNLOCK(node);
+}
+
+void
+tmpfs_ref_node_locked(struct tmpfs_node *node)
+{
+
+	TMPFS_NODE_ASSERT_LOCKED(node);
+	KASSERT(node->tn_refcount > 0, ("node %p zero refcount", node));
+	KASSERT(node->tn_refcount < UINT_MAX, ("node %p refcount %u", node,
+	    node->tn_refcount));
+	node->tn_refcount++;
+}
+
 /*
  * Allocates a new node of type 'type' inside the 'tmp' mount point, with
  * its owner set to 'uid', its group to 'gid' and its mode set to 'mode',
@@ -206,6 +226,7 @@ tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *tmp, enum vtype type,
 	nnode->tn_gid = gid;
 	nnode->tn_mode = mode;
 	nnode->tn_id = alloc_unr(tmp->tm_ino_unr);
+	nnode->tn_refcount = 1;
 
 	/* Type-specific initialization. */
 	switch (nnode->tn_type) {
@@ -259,7 +280,9 @@ tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *tmp, enum vtype type,
 
 	TMPFS_LOCK(tmp);
 	LIST_INSERT_HEAD(&tmp->tm_nodes_used, nnode, tn_entries);
+	nnode->tn_attached = true;
 	tmp->tm_nodes_inuse++;
+	tmp->tm_refcount++;
 	TMPFS_UNLOCK(tmp);
 
 	*node = nnode;
@@ -273,18 +296,40 @@ tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *tmp, enum vtype type,
 void
 tmpfs_free_node(struct tmpfs_mount *tmp, struct tmpfs_node *node)
 {
+
+	TMPFS_LOCK(tmp);
+	TMPFS_NODE_LOCK(node);
+	if (!tmpfs_free_node_locked(tmp, node, false)) {
+		TMPFS_NODE_UNLOCK(node);
+		TMPFS_UNLOCK(tmp);
+	}
+}
+
+bool
+tmpfs_free_node_locked(struct tmpfs_mount *tmp, struct tmpfs_node *node,
+    bool detach)
+{
 	vm_object_t uobj;
 
+	TMPFS_MP_ASSERT_LOCKED(tmp);
+	TMPFS_NODE_ASSERT_LOCKED(node);
+	KASSERT(node->tn_refcount > 0, ("node %p refcount zero", node));
+
+	node->tn_refcount--;
+	if (node->tn_attached && (detach || node->tn_refcount == 0)) {
+		MPASS(tmp->tm_nodes_inuse > 0);
+		tmp->tm_nodes_inuse--;
+		LIST_REMOVE(node, tn_entries);
+		node->tn_attached = false;
+	}
+	if (node->tn_refcount > 0)
+		return (false);
+
 #ifdef INVARIANTS
-	TMPFS_NODE_LOCK(node);
 	MPASS(node->tn_vnode == NULL);
 	MPASS((node->tn_vpstate & TMPFS_VNODE_ALLOCATING) == 0);
-	TMPFS_NODE_UNLOCK(node);
 #endif
-
-	TMPFS_LOCK(tmp);
-	LIST_REMOVE(node, tn_entries);
-	tmp->tm_nodes_inuse--;
+	TMPFS_NODE_UNLOCK(node);
 	TMPFS_UNLOCK(tmp);
 
 	switch (node->tn_type) {
@@ -324,6 +369,9 @@ tmpfs_free_node(struct tmpfs_mount *tmp, struct tmpfs_node *node)
 
 	free_unr(tmp->tm_ino_unr, node->tn_id);
 	uma_zfree(tmp->tm_node_pool, node);
+	TMPFS_LOCK(tmp);
+	tmpfs_free_tmp(tmp);
+	return (true);
 }
 
 static __inline uint32_t
@@ -469,13 +517,16 @@ tmpfs_alloc_vp(struct mount *mp, struct tmpfs_node *node, int lkflag,
     struct vnode **vpp)
 {
 	struct vnode *vp;
+	struct tmpfs_mount *tm;
 	vm_object_t object;
 	int error;
 
 	error = 0;
-loop:
+	tm = VFS_TO_TMPFS(mp);
 	TMPFS_NODE_LOCK(node);
-loop1:
+	tmpfs_ref_node_locked(node);
+loop:
+	TMPFS_NODE_ASSERT_LOCKED(node);
 	if ((vp = node->tn_vnode) != NULL) {
 		MPASS((node->tn_vpstate & TMPFS_VNODE_DOOMED) == 0);
 		VI_LOCK(vp);
@@ -495,12 +546,14 @@ loop1:
 				msleep(&node->tn_vnode, TMPFS_NODE_MTX(node),
 				    0, "tmpfsE", 0);
 			}
-			goto loop1;
+			goto loop;
 		}
 		TMPFS_NODE_UNLOCK(node);
 		error = vget(vp, lkflag | LK_INTERLOCK, curthread);
-		if (error == ENOENT)
+		if (error == ENOENT) {
+			TMPFS_NODE_LOCK(node);
 			goto loop;
+		}
 		if (error != 0) {
 			vp = NULL;
 			goto out;
@@ -512,6 +565,7 @@ loop1:
 		 */
 		if (node->tn_vnode == NULL || node->tn_vnode != vp) {
 			vput(vp);
+			TMPFS_NODE_LOCK(node);
 			goto loop;
 		}
 
@@ -533,11 +587,9 @@ loop1:
 	if (node->tn_vpstate & TMPFS_VNODE_ALLOCATING) {
 		node->tn_vpstate |= TMPFS_VNODE_WANT;
 		error = msleep((caddr_t) &node->tn_vpstate,
-		    TMPFS_NODE_MTX(node), PDROP | PCATCH,
-		    "tmpfs_alloc_vp", 0);
-		if (error)
-			return error;
-
+		    TMPFS_NODE_MTX(node), 0, "tmpfs_alloc_vp", 0);
+		if (error != 0)
+			goto out;
 		goto loop;
 	} else
 		node->tn_vpstate |= TMPFS_VNODE_ALLOCATING;
@@ -611,16 +663,17 @@ unlock:
 		TMPFS_NODE_UNLOCK(node);
 
 out:
-	*vpp = vp;
+	if (error == 0) {
+		*vpp = vp;
 
 #ifdef INVARIANTS
-	if (error == 0) {
 		MPASS(*vpp != NULL && VOP_ISLOCKED(*vpp));
 		TMPFS_NODE_LOCK(node);
 		MPASS(*vpp == node->tn_vnode);
 		TMPFS_NODE_UNLOCK(node);
-	}
 #endif
+	}
+	tmpfs_free_node(tm, node);
 
 	return (error);
 }
diff --git a/sys/fs/tmpfs/tmpfs_vfsops.c b/sys/fs/tmpfs/tmpfs_vfsops.c
index 88b12ef..188e476 100644
--- a/sys/fs/tmpfs/tmpfs_vfsops.c
+++ b/sys/fs/tmpfs/tmpfs_vfsops.c
@@ -222,6 +222,7 @@ tmpfs_mount(struct mount *mp)
 	mtx_init(&tmp->tm_allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF);
 	tmp->tm_nodes_max = nodes_max;
 	tmp->tm_nodes_inuse = 0;
+	tmp->tm_refcount = 1;
 	tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX;
 	LIST_INIT(&tmp->tm_nodes_used);
 
@@ -304,11 +305,35 @@ tmpfs_unmount(struct mount *mp, int mntflags)
 
 	TMPFS_LOCK(tmp);
 	while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) {
-		TMPFS_UNLOCK(tmp);
+		TMPFS_NODE_LOCK(node);
 		if (node->tn_type == VDIR)
 			tmpfs_dir_destroy(tmp, node);
-		tmpfs_free_node(tmp, node);
-		TMPFS_LOCK(tmp);
+		if (tmpfs_free_node_locked(tmp, node, true))
+			TMPFS_LOCK(tmp);
+		else
+			TMPFS_NODE_UNLOCK(node);
+	}
+
+	mp->mnt_data = NULL;
+	tmpfs_free_tmp(tmp);
+	vfs_write_resume(mp, VR_START_WRITE);
+
+	MNT_ILOCK(mp);
+	mp->mnt_flag &= ~MNT_LOCAL;
+	MNT_IUNLOCK(mp);
+
+	return (0);
+}
+
+void
+tmpfs_free_tmp(struct tmpfs_mount *tmp)
+{
+
+	MPASS(tmp->tm_refcount > 0);
+	tmp->tm_refcount--;
+	if (tmp->tm_refcount > 0) {
+		TMPFS_UNLOCK(tmp);
+		return;
 	}
 	TMPFS_UNLOCK(tmp);
 
@@ -320,16 +345,7 @@ tmpfs_unmount(struct mount *mp, int mntflags)
 	MPASS(tmp->tm_pages_used == 0);
 	MPASS(tmp->tm_nodes_inuse == 0);
 
-	/* Throw away the tmpfs_mount structure. */
-	free(mp->mnt_data, M_TMPFSMNT);
-	mp->mnt_data = NULL;
-	vfs_write_resume(mp, VR_START_WRITE);
-
-	MNT_ILOCK(mp);
-	mp->mnt_flag &= ~MNT_LOCAL;
-	MNT_IUNLOCK(mp);
-
-	return (0);
+	free(tmp, M_TMPFSMNT);
 }
 
 static int
@@ -347,36 +363,36 @@ static int
 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags,
     struct vnode **vpp)
 {
-	boolean_t found;
 	struct tmpfs_fid *tfhp;
 	struct tmpfs_mount *tmp;
 	struct tmpfs_node *node;
+	int error;
 
 	tmp = VFS_TO_TMPFS(mp);
 
 	tfhp = (struct tmpfs_fid *)fhp;
 	if (tfhp->tf_len != sizeof(struct tmpfs_fid))
-		return EINVAL;
+		return (EINVAL);
 
 	if (tfhp->tf_id >= tmp->tm_nodes_max)
-		return EINVAL;
-
-	found = FALSE;
+		return (EINVAL);
 
 	TMPFS_LOCK(tmp);
 	LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
 		if (node->tn_id == tfhp->tf_id &&
 		    node->tn_gen == tfhp->tf_gen) {
-			found = TRUE;
+			tmpfs_ref_node(node);
 			break;
 		}
 	}
 	TMPFS_UNLOCK(tmp);
 
-	if (found)
-		return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp));
-
-	return (EINVAL);
+	if (node != NULL) {
+		error = tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp);
+		tmpfs_free_node(tmp, node);
+	} else
+		error = EINVAL;
+	return (error);
 }
 
 /* ARGSUSED2 */
diff --git a/sys/fs/tmpfs/tmpfs_vnops.c b/sys/fs/tmpfs/tmpfs_vnops.c
index 1b498de..becc72b 100644
--- a/sys/fs/tmpfs/tmpfs_vnops.c
+++ b/sys/fs/tmpfs/tmpfs_vnops.c
@@ -82,7 +82,8 @@ tmpfs_lookup(struct vop_cachedlookup_args *v)
 	struct vnode **vpp = v->a_vpp;
 	struct componentname *cnp = v->a_cnp;
 	struct tmpfs_dirent *de;
-	struct tmpfs_node *dnode;
+	struct tmpfs_node *dnode, *pnode;
+	struct tmpfs_mount *tm;
 	int error;
 
 	dnode = VP_TO_TMPFS_DIR(dvp);
@@ -104,8 +105,12 @@ tmpfs_lookup(struct vop_cachedlookup_args *v)
 		goto out;
 	}
 	if (cnp->cn_flags & ISDOTDOT) {
+		tm = VFS_TO_TMPFS(dvp->v_mount);
+		pnode = dnode->tn_dir.tn_parent;
+		tmpfs_ref_node(pnode);
 		error = vn_vget_ino_gen(dvp, tmpfs_vn_get_ino_alloc,
-		    dnode->tn_dir.tn_parent, cnp->cn_lkflags, vpp);
+		    pnode, cnp->cn_lkflags, vpp);
+		tmpfs_free_node(tm, pnode);
 		if (error != 0)
 			goto out;
 	} else if (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') {