bsd/miscfs/mockfs/mockfs_vfsops.c

   1 /*
   2  * Copyright (c) 2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <kern/assert.h>
  30 #include <kern/debug.h>
  31 #include <libkern/libkern.h>
  32 #include <miscfs/mockfs/mockfs.h>
  33 #include <miscfs/mockfs/mockfs_fsnode.h>
  34 #include <miscfs/mockfs/mockfs_vnops.h>
  35 #include <miscfs/specfs/specdev.h>
  36 #include <sys/disk.h>
  37 #include <sys/errno.h>
  38 #include <sys/malloc.h>
  39 #include <sys/mount_internal.h>
  40 #include <sys/vnode_internal.h>
  41
  42 lck_attr_t * mockfs_mtx_attr = (lck_attr_t *) 0;
  43 lck_grp_attr_t * mockfs_grp_attr = (lck_grp_attr_t *) 0;
  44 lck_grp_t * mockfs_mtx_grp = (lck_grp_t *) 0;
  45
  46 int mockfs_mountroot(mount_t mp, vnode_t rvp, __unused vfs_context_t ctx);
  47
  48 /*
  49  * Functions that are part of the mockfs_vfsops structure.
  50  */
  51 int mockfs_unmount(__unused struct mount *mp, __unused int mntflags, __unused vfs_context_t ctx);
  52 int mockfs_root(mount_t mp, vnode_t * vpp, __unused vfs_context_t ctx);
  53 int mockfs_sync(__unused struct mount *mp, __unused int waitfor, __unused vfs_context_t ctx);
  54 int mockfs_init(__unused struct vfsconf * vfsc);
  55
  56 /*
  57  * mockfs_mountroot:
  58  *   Given a mount (mp) and a vnode for the root device (rvp), builds a fake filesystem for rvp.  This consists
  59  *   of three nodes; a directory node (to serve as a mountpoint for devfs), a file node meant to serve as an
  60  *   executable frontend for rootvp (we will assume that rootvp is an executable, that the kernel can subsequently
  61  *   run), and the root node for the mockfs filesystem.  The structure of mockfs is memory-backed; only the
  62  *   contents of the file node refer to the backing device.
  63  *
  64  * Returns 0 on success, or an error.
  65  */
  66 int
  67 mockfs_mountroot(mount_t mp, vnode_t rvp, __unused vfs_context_t ctx)
  68 {
  69         int rvalue = 0;
  70         mockfs_fsnode_t root_fsnode = NULL;
  71         mockfs_fsnode_t dev_fsnode = NULL;
  72         mockfs_fsnode_t file_fsnode = NULL;
  73         mockfs_mount_t mockfs_mount_data = NULL;
  74         dk_memdev_info_t memdev_info;
  75
  76         /*
  77          * TODO: Validate that the device at least LOOKS like a mach-o (has a sane header); this would prevent us
  78          *   from causing EBADMACHO panics further along the boot path.
  79          */
  80
  81         /*
  82          * There are no M_MOCKFS* definitions at the moment, just use M_TEMP.
  83          */
  84
  85         MALLOC(mockfs_mount_data, mockfs_mount_t, sizeof(*mockfs_mount_data), M_TEMP, M_WAITOK | M_ZERO);
  86         mockfs_fsnode_create(mp, MOCKFS_ROOT, &root_fsnode);
  87         mockfs_fsnode_create(mp, MOCKFS_DEV, &dev_fsnode);
  88         mockfs_fsnode_create(mp, MOCKFS_FILE, &file_fsnode);
  89
  90         if (!mockfs_mount_data || !root_fsnode || !dev_fsnode || !file_fsnode) {
  91                 rvalue = ENOMEM;
  92                 goto done;
  93         }
  94
  95         /*
  96          * If rvp is a memory device (with a few caveats), we can point to the same physical memory as the device
  97          *   and avoid pointless paging/copying; query the device node for the information we need to determine
  98          *   if we can do this.
  99          */
 100         bzero(&memdev_info, sizeof(memdev_info));
 101
 102         if (!VNOP_IOCTL(rvp, DKIOCGETMEMDEVINFO, (caddr_t)&memdev_info, 0, NULL)) {
 103                 /*
 104                  * For the moment, we won't try to optimize when mi_phys is true.
 105                  */
 106                 if (!mockfs_mount_data->mockfs_physical_memory) {
 107                         mockfs_mount_data->mockfs_memory_backed = memdev_info.mi_mdev;
 108                         mockfs_mount_data->mockfs_physical_memory = memdev_info.mi_phys;
 109                         mockfs_mount_data->mockfs_memdev_base = memdev_info.mi_base;
 110                         mockfs_mount_data->mockfs_memdev_size = memdev_info.mi_size;
 111                 }
 112         }
 113
 114         lck_mtx_init(&mockfs_mount_data->mockfs_mnt_mtx, mockfs_mtx_grp, mockfs_mtx_attr);
 115
 116         /*
 117          * All of the needed nodes/structures have been set up; now we just need to establish the relationships
 118          *   between the various mockfs nodes.
 119          */
 120         if ((rvalue = mockfs_fsnode_adopt(root_fsnode, dev_fsnode))) {
 121                 goto done;
 122         }
 123
 124         if ((rvalue = mockfs_fsnode_adopt(root_fsnode, file_fsnode))) {
 125                 goto done;
 126         }
 127
 128         mockfs_mount_data->mockfs_root = root_fsnode;
 129         mp->mnt_data = (typeof(mp->mnt_data))mockfs_mount_data;
 130
 131 done:
 132         if (rvalue) {
 133                 if (file_fsnode) {
 134                         mockfs_fsnode_destroy(file_fsnode);
 135                 }
 136                 if (dev_fsnode) {
 137                         mockfs_fsnode_destroy(dev_fsnode);
 138                 }
 139                 if (root_fsnode) {
 140                         mockfs_fsnode_destroy(root_fsnode);
 141                 }
 142                 if (mockfs_mount_data) {
 143                         lck_mtx_destroy(&mockfs_mount_data->mockfs_mnt_mtx, mockfs_mtx_grp);
 144                         FREE(mockfs_mount_data, M_TEMP);
 145                 }
 146         }
 147
 148         return rvalue;
 149 }
 150
 151 /*
 152  * mockfs_unmount:
 153  *   Given a mount (mp), and associated flags (mntflags), performs the necessary teardown to destroy the mount.
 154  *
 155  * Returns 0 on success, or an error.
 156  */
 157 int
 158 mockfs_unmount(struct mount *mp, int mntflags, __unused vfs_context_t ctx)
 159 {
 160         int rvalue;
 161         int vflush_flags;
 162         mockfs_fsnode_t root_fsnode;
 163         mockfs_mount_t mockfs_mnt;
 164
 165         vflush_flags = 0;
 166         mockfs_mnt = (mockfs_mount_t) mp->mnt_data;
 167
 168         /*
 169          * Reclaim the vnodes for the mount (forcibly, if requested; given that mockfs only support mountroot
 170          *   at the moment, this should ALWAYS be forced),
 171          */
 172         if (mntflags & MNT_FORCE) {
 173                 vflush_flags |= FORCECLOSE;
 174         }
 175
 176         rvalue = vflush(mp, NULL, vflush_flags);
 177
 178         if (rvalue) {
 179                 return rvalue;
 180         }
 181
 182         /*
 183          * Past this point, errors are likely to be unrecoverable, so panic if we're given any excuse; we
 184          *   need to teardown the mockfs_mnt data now, so that VFS can cleanup the mount structure.  Note
 185          *   that clearing mockfs_root before destroying the fsnode tree is related to an implementation
 186          *   detail of mockfs_fsnode_destroy (which will refuse to destroy the root node).
 187          */
 188         root_fsnode = mockfs_mnt->mockfs_root;
 189         mockfs_mnt->mockfs_root = NULL;
 190         rvalue = mockfs_fsnode_destroy(root_fsnode);
 191
 192         if (rvalue) {
 193                 panic("mockfs_unmount: Failed to destroy the fsnode tree");
 194         }
 195
 196         lck_mtx_destroy(&mockfs_mnt->mockfs_mnt_mtx, mockfs_mtx_grp);
 197         FREE(mockfs_mnt, M_TEMP);
 198         mp->mnt_data = NULL;
 199
 200         return rvalue;
 201 }
 202
 203 /*
 204  * mockfs_root:
 205  *   Given a mount (mp), returns the root vnode (*vpp) for that mount with an iocount.
 206  *
 207  * Returns 0 on success, or an error.
 208  */
 209 int
 210 mockfs_root(mount_t mp, vnode_t * vpp, __unused vfs_context_t ctx)
 211 {
 212         int rvalue;
 213
 214         rvalue = mockfs_fsnode_vnode(((mockfs_mount_t) mp->mnt_data)->mockfs_root, vpp);
 215         return rvalue;
 216 }
 217
 218 /*
 219  * mockfs_sync:
 220  *  Returns success because we're a read-only filesystem.
 221  *
 222  * Returns 0.
 223  */
 224 int
 225 mockfs_sync(__unused struct mount *mp, __unused int waitfor, __unused vfs_context_t ctx)
 226 {
 227         return 0;
 228 }
 229
 230 /*
 231  * mockfs_init:
 232  *   Run once (during VFS initialization); takes care of generic mockfs initialization (which for now, means
 233  *   global lock information).
 234  *
 235  * Returns 0 on success, or an error.
 236  */
 237 int
 238 mockfs_init(__unused struct vfsconf * vfsc)
 239 {
 240         mockfs_mtx_attr = lck_attr_alloc_init();
 241         mockfs_grp_attr = lck_grp_attr_alloc_init();
 242         mockfs_mtx_grp = lck_grp_alloc_init("mockfs-mutex", mockfs_grp_attr);
 243
 244         /*
 245          * If we've failed to allocate this early in boot, something is horrendously wrong; it should be fine to
 246          *   panic (for now).
 247          */
 248         if (!mockfs_mtx_attr || !mockfs_grp_attr || !mockfs_mtx_grp) {
 249                 panic("mockfs_init failed to allocate lock information");
 250         }
 251
 252         return 0;
 253 }
 254
 255 struct vfsops mockfs_vfsops = {
 256         .vfs_unmount = mockfs_unmount,
 257         .vfs_root = mockfs_root,
 258         .vfs_sync = mockfs_sync,
 259         .vfs_init = mockfs_init,
 260 };