--- /dev/null
+/*
+ * Copyright (c) 2016 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+/*-
+ * Portions Copyright (c) 1992, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software donated to Berkeley by
+ * Jan-Simon Pendry.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * @(#)null_subr.c 8.7 (Berkeley) 5/14/95
+ *
+ * $FreeBSD$
+ */
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mount.h>
+#include <sys/proc.h>
+#include <sys/vnode.h>
+
+#include "nullfs.h"
+
+/*
+ * Null layer cache:
+ * Each cache entry holds a reference to the lower vnode
+ * along with a pointer to the alias vnode. When an
+ * entry is added the lower vnode is VREF'd. When the
+ * alias is removed the lower vnode is vrele'd.
+ */
+
+#define NULL_HASH_SIZE (desiredvnodes / 10)
+
+/* osx doesn't really have the functionality freebsd uses here..gonna try this
+ * hacked hash...*/
+#define NULL_NHASH(vp) (&null_node_hashtbl[((((uintptr_t)vp) >> vnsz2log) + (uintptr_t)vnode_mount(vp)) & null_hash_mask])
+
+static LIST_HEAD(null_node_hashhead, null_node) * null_node_hashtbl;
+static lck_mtx_t null_hashmtx;
+static lck_attr_t * null_hashlck_attr;
+static lck_grp_t * null_hashlck_grp;
+static lck_grp_attr_t * null_hashlck_grp_attr;
+static u_long null_hash_mask;
+
+/* os x doesn't have hashes built into vnode. gonna try doing what freebsd does
+ anyway
+ Don't want to create a dependency on vnode_internal.h and the real struct
+ vnode.
+ 9 is an eyeball of the log 2 size of vnode */
+static int vnsz2log = 9;
+
+static int null_hashins(struct mount *, struct null_node *, struct vnode **);
+
+int
+nullfs_init_lck(lck_mtx_t * lck)
+{
+ int error = 1;
+ if (lck && null_hashlck_grp && null_hashlck_attr) {
+ lck_mtx_init(lck, null_hashlck_grp, null_hashlck_attr);
+ error = 0;
+ }
+ return error;
+}
+
+int
+nullfs_destroy_lck(lck_mtx_t * lck)
+{
+ int error = 1;
+ if (lck && null_hashlck_grp) {
+ lck_mtx_destroy(lck, null_hashlck_grp);
+ error = 0;
+ }
+ return error;
+}
+
+/*
+ * Initialise cache headers
+ */
+int
+nullfs_init(__unused struct vfsconf * vfsp)
+{
+ NULLFSDEBUG("%s\n", __FUNCTION__);
+
+ /* assuming for now that this happens immediately and by default after fs
+ * installation */
+ null_hashlck_grp_attr = lck_grp_attr_alloc_init();
+ if (null_hashlck_grp_attr == NULL) {
+ goto error;
+ }
+ null_hashlck_grp = lck_grp_alloc_init("com.apple.filesystems.nullfs", null_hashlck_grp_attr);
+ if (null_hashlck_grp == NULL) {
+ goto error;
+ }
+ null_hashlck_attr = lck_attr_alloc_init();
+ if (null_hashlck_attr == NULL) {
+ goto error;
+ }
+
+ lck_mtx_init(&null_hashmtx, null_hashlck_grp, null_hashlck_attr);
+ null_node_hashtbl = hashinit(NULL_HASH_SIZE, M_TEMP, &null_hash_mask);
+ NULLFSDEBUG("%s finished\n", __FUNCTION__);
+ return (0);
+error:
+ printf("NULLFS: failed to get lock element\n");
+ if (null_hashlck_grp_attr) {
+ lck_grp_attr_free(null_hashlck_grp_attr);
+ null_hashlck_grp_attr = NULL;
+ }
+ if (null_hashlck_grp) {
+ lck_grp_free(null_hashlck_grp);
+ null_hashlck_grp = NULL;
+ }
+ if (null_hashlck_attr) {
+ lck_attr_free(null_hashlck_attr);
+ null_hashlck_attr = NULL;
+ }
+ return KERN_FAILURE;
+}
+
+int
+nullfs_uninit()
+{
+ /* This gets called when the fs is uninstalled, there wasn't an exact
+ * equivalent in vfsops */
+ lck_mtx_destroy(&null_hashmtx, null_hashlck_grp);
+ FREE(null_node_hashtbl, M_TEMP);
+ if (null_hashlck_grp_attr) {
+ lck_grp_attr_free(null_hashlck_grp_attr);
+ null_hashlck_grp_attr = NULL;
+ }
+ if (null_hashlck_grp) {
+ lck_grp_free(null_hashlck_grp);
+ null_hashlck_grp = NULL;
+ }
+ if (null_hashlck_attr) {
+ lck_attr_free(null_hashlck_attr);
+ null_hashlck_attr = NULL;
+ }
+ return (0);
+}
+
+/*
+ * Find the nullfs vnode mapped to lowervp. Return it in *vpp with an iocount if found.
+ * Return 0 on success. On failure *vpp will be null and a non-zero error code will be returned.
+ */
+int
+null_hashget(struct mount * mp, struct vnode * lowervp, struct vnode ** vpp)
+{
+ struct null_node_hashhead * hd;
+ struct null_node * a;
+ struct vnode * vp;
+ int error = ENOENT;
+
+ /*
+ * Find hash base, and then search the (two-way) linked
+ * list looking for a null_node structure which is referencing
+ * the lower vnode. We only give up our reference at reclaim so
+ * just check whether the lowervp has gotten pulled from under us
+ */
+ hd = NULL_NHASH(lowervp);
+ lck_mtx_lock(&null_hashmtx);
+ LIST_FOREACH(a, hd, null_hash)
+ {
+ if (a->null_lowervp == lowervp && vnode_mount(NULLTOV(a)) == mp) {
+ vp = NULLTOV(a);
+ if (a->null_lowervid != vnode_vid(lowervp)) {
+ /*lowervp has reved */
+ error = EIO;
+ } else {
+ /* if we found something then get an iocount on it */
+ error = vnode_getwithvid(vp, a->null_myvid);
+ if (error == 0) {
+ *vpp = vp;
+ }
+ }
+ break;
+ }
+ }
+ lck_mtx_unlock(&null_hashmtx);
+ return error;
+}
+
+/*
+ * Act like null_hashget, but add passed null_node to hash if no existing
+ * node found.
+ */
+static int
+null_hashins(struct mount * mp, struct null_node * xp, struct vnode ** vpp)
+{
+ struct null_node_hashhead * hd;
+ struct null_node * oxp;
+ struct vnode * ovp;
+ int error = 0;
+
+ hd = NULL_NHASH(xp->null_lowervp);
+ lck_mtx_lock(&null_hashmtx);
+ LIST_FOREACH(oxp, hd, null_hash)
+ {
+ if (oxp->null_lowervp == xp->null_lowervp && vnode_mount(NULLTOV(oxp)) == mp) {
+ /*
+ * See null_hashget for a description of this
+ * operation.
+ */
+ ovp = NULLTOV(oxp);
+ if (oxp->null_lowervid != vnode_vid(oxp->null_lowervp)) {
+ /*vp doesn't exist so return null (not sure we are actually gonna catch
+ recycle right now
+ This is an exceptional case right now, it suggests the vnode we are
+ trying to add has been recycled
+ don't add it.*/
+ error = EIO;
+ goto end;
+ }
+ /* if we found something in the hash map then grab an iocount */
+ error = vnode_getwithvid(ovp, oxp->null_myvid);
+ if (error == 0) {
+ *vpp = ovp;
+ }
+ goto end;
+ }
+ }
+ /* if it wasn't in the hash map then the vnode pointed to by xp already has a
+ * iocount so don't bother */
+ LIST_INSERT_HEAD(hd, xp, null_hash);
+ xp->null_flags |= NULL_FLAG_HASHED;
+end:
+ lck_mtx_unlock(&null_hashmtx);
+ return error;
+}
+
+/*
+ * Remove node from hash.
+ */
+void
+null_hashrem(struct null_node * xp)
+{
+ lck_mtx_lock(&null_hashmtx);
+ LIST_REMOVE(xp, null_hash);
+ lck_mtx_unlock(&null_hashmtx);
+}
+
+static struct null_node *
+null_nodecreate(struct vnode * lowervp)
+{
+ struct null_node * xp;
+
+ MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK | M_ZERO);
+ if (xp != NULL) {
+ if (lowervp) {
+ xp->null_lowervp = lowervp;
+ xp->null_lowervid = vnode_vid(lowervp);
+ }
+ }
+ return xp;
+}
+
+/* assumption is that vnode has iocount on it after vnode create */
+int
+null_getnewvnode(
+ struct mount * mp, struct vnode * lowervp, struct vnode * dvp, struct vnode ** vpp, struct componentname * cnp, int root)
+{
+ struct vnode_fsparam vnfs_param;
+ int error = 0;
+ enum vtype type = VDIR;
+ struct null_node * xp = null_nodecreate(lowervp);
+
+ if (xp == NULL) {
+ return ENOMEM;
+ }
+
+ if (lowervp) {
+ type = vnode_vtype(lowervp);
+ }
+
+ vnfs_param.vnfs_mp = mp;
+ vnfs_param.vnfs_vtype = type;
+ vnfs_param.vnfs_str = "nullfs";
+ vnfs_param.vnfs_dvp = dvp;
+ vnfs_param.vnfs_fsnode = (void *)xp;
+ vnfs_param.vnfs_vops = nullfs_vnodeop_p;
+ vnfs_param.vnfs_markroot = root;
+ vnfs_param.vnfs_marksystem = 0;
+ vnfs_param.vnfs_rdev = 0;
+ vnfs_param.vnfs_filesize = 0; // set this to 0 since we should only be shadowing non-regular files
+ vnfs_param.vnfs_cnp = cnp;
+ vnfs_param.vnfs_flags = VNFS_ADDFSREF;
+
+ error = vnode_create(VNCREATE_FLAVOR, VCREATESIZE, &vnfs_param, vpp);
+ if (error == 0) {
+ xp->null_vnode = *vpp;
+ xp->null_myvid = vnode_vid(*vpp);
+ vnode_settag(*vpp, VT_NULL);
+ } else {
+ FREE(xp, M_TEMP);
+ }
+ return error;
+}
+
+/*
+ * Make a new or get existing nullfs node.
+ * Vp is the alias vnode, lowervp is the lower vnode.
+ *
+ * lowervp is assumed to have an iocount on it from the caller
+ */
+int
+null_nodeget(
+ struct mount * mp, struct vnode * lowervp, struct vnode * dvp, struct vnode ** vpp, struct componentname * cnp, int root)
+{
+ struct vnode * vp;
+ int error;
+
+ /* Lookup the hash firstly. */
+ error = null_hashget(mp, lowervp, vpp);
+ /* ENOENT means it wasn't found, EIO is a failure we should bail from, 0 is it
+ * was found */
+ if (error != ENOENT) {
+ /* null_hashget checked the vid, so if we got something here its legit to
+ * the best of our knowledge*/
+ /* if we found something then there is an iocount on vpp,
+ if we didn't find something then vpp shouldn't be used by the caller */
+ return error;
+ }
+
+ /*
+ * We do not serialize vnode creation, instead we will check for
+ * duplicates later, when adding new vnode to hash.
+ */
+ error = vnode_ref(lowervp); // take a ref on lowervp so we let the system know we care about it
+ if(error)
+ {
+ // Failed to get a reference on the lower vp so bail. Lowervp may be gone already.
+ return error;
+ }
+
+ error = null_getnewvnode(mp, lowervp, dvp, &vp, cnp, root);
+
+ if (error) {
+ vnode_rele(lowervp);
+ return (error);
+ }
+
+ /*
+ * Atomically insert our new node into the hash or vget existing
+ * if someone else has beaten us to it.
+ */
+ error = null_hashins(mp, VTONULL(vp), vpp);
+ if (error || *vpp != NULL) {
+ /* recycle will call reclaim which will get rid of the internals */
+ vnode_recycle(vp);
+ vnode_put(vp);
+ /* if we found vpp, then null_hashins put an iocount on it */
+ return error;
+ }
+
+ /* vp has an iocount from null_getnewvnode */
+ *vpp = vp;
+
+ return (0);
+}
projects / apple / xnu.git / blobdiff