null_vfsops.c revision 1.88
1 /* $NetBSD: null_vfsops.c,v 1.88 2014/04/16 18:55:19 maxv Exp $ */ 2 3 /* 4 * Copyright (c) 1999 National Aeronautics & Space Administration 5 * All rights reserved. 6 * 7 * This software was written by William Studenmund of the 8 * Numerical Aerospace Simulation Facility, NASA Ames Research Center. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the National Aeronautics & Space Administration 19 * nor the names of its contributors may be used to endorse or promote 20 * products derived from this software without specific prior written 21 * permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB- 27 * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 28 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33 * POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 /* 37 * Copyright (c) 1992, 1993, 1995 38 * The Regents of the University of California. All rights reserved. 39 * 40 * This code is derived from software donated to Berkeley by 41 * Jan-Simon Pendry. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * from: Id: lofs_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp 68 * from: @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 69 * @(#)null_vfsops.c 8.7 (Berkeley) 5/14/95 70 */ 71 72 /* 73 * Null file-system: VFS operations. 74 * 75 * See null_vnops.c for a description. 76 */ 77 78 #include <sys/cdefs.h> 79 __KERNEL_RCSID(0, "$NetBSD: null_vfsops.c,v 1.88 2014/04/16 18:55:19 maxv Exp $"); 80 81 #include <sys/param.h> 82 #include <sys/systm.h> 83 #include <sys/sysctl.h> 84 #include <sys/vnode.h> 85 #include <sys/mount.h> 86 #include <sys/namei.h> 87 #include <sys/malloc.h> 88 #include <sys/module.h> 89 90 #include <miscfs/nullfs/null.h> 91 #include <miscfs/genfs/layer_extern.h> 92 93 MODULE(MODULE_CLASS_VFS, null, "layerfs"); 94 95 VFS_PROTOS(nullfs); 96 97 static struct sysctllog *nullfs_sysctl_log; 98 99 int 100 nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len) 101 { 102 struct vnode *lowerrootvp, *vp; 103 struct null_args *args = data; 104 struct null_mount *nmp; 105 struct layer_mount *lmp; 106 struct pathbuf *pb; 107 struct nameidata nd; 108 int error; 109 110 if (args == NULL) 111 return EINVAL; 112 if (*data_len < sizeof(*args)) 113 return EINVAL; 114 115 if (mp->mnt_flag & MNT_GETARGS) { 116 lmp = MOUNTTOLAYERMOUNT(mp); 117 if (lmp == NULL) 118 return EIO; 119 args->la.target = NULL; 120 *data_len = sizeof(*args); 121 return 0; 122 } 123 124 /* Update is not supported. */ 125 if (mp->mnt_flag & MNT_UPDATE) 126 return EOPNOTSUPP; 127 128 /* Find the lower vnode and lock it. */ 129 error = pathbuf_copyin(args->la.target, &pb); 130 if (error) { 131 return error; 132 } 133 NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb); 134 if ((error = namei(&nd)) != 0) { 135 pathbuf_destroy(pb); 136 return error; 137 } 138 lowerrootvp = nd.ni_vp; 139 pathbuf_destroy(pb); 140 141 /* Create the mount point. */ 142 nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP); 143 mp->mnt_data = nmp; 144 nmp->nullm_vfs = lowerrootvp->v_mount; 145 if (nmp->nullm_vfs->mnt_flag & MNT_LOCAL) 146 mp->mnt_flag |= MNT_LOCAL; 147 148 /* 149 * Make sure that the mount point is sufficiently initialized 150 * that the node create call will work. 151 */ 152 vfs_getnewfsid(mp); 153 154 nmp->nullm_size = sizeof(struct null_node); 155 nmp->nullm_tag = VT_NULL; 156 nmp->nullm_bypass = layer_bypass; 157 nmp->nullm_alloc = layer_node_alloc; /* the default alloc is fine */ 158 nmp->nullm_vnodeop_p = null_vnodeop_p; 159 mutex_init(&nmp->nullm_hashlock, MUTEX_DEFAULT, IPL_NONE); 160 nmp->nullm_node_hashtbl = hashinit(desiredvnodes, HASH_LIST, true, 161 &nmp->nullm_node_hash); 162 163 /* Setup a null node for root vnode. */ 164 VOP_UNLOCK(lowerrootvp); 165 error = layer_node_create(mp, lowerrootvp, &vp); 166 if (error) { 167 vrele(lowerrootvp); 168 hashdone(nmp->nullm_node_hashtbl, HASH_LIST, 169 nmp->nullm_node_hash); 170 kmem_free(nmp, sizeof(struct null_mount)); 171 return error; 172 } 173 /* 174 * Keep a held reference to the root vnode. It will be released on 175 * umount. Note: nullfs is MP-safe. 176 */ 177 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 178 vp->v_vflag |= VV_ROOT; 179 nmp->nullm_rootvp = vp; 180 mp->mnt_iflag |= IMNT_MPSAFE; 181 VOP_UNLOCK(vp); 182 183 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target, 184 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp); 185 return error; 186 } 187 188 int 189 nullfs_unmount(struct mount *mp, int mntflags) 190 { 191 struct null_mount *nmp = MOUNTTONULLMOUNT(mp); 192 struct vnode *null_rootvp = nmp->nullm_rootvp; 193 int error, flags = 0; 194 195 if (mntflags & MNT_FORCE) 196 flags |= FORCECLOSE; 197 198 if (null_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0) 199 return EBUSY; 200 201 if ((error = vflush(mp, null_rootvp, flags)) != 0) 202 return error; 203 204 /* Eliminate all activity and release the vnode. */ 205 vgone(null_rootvp); 206 207 /* Finally, destroy the mount point structures. */ 208 hashdone(nmp->nullm_node_hashtbl, HASH_LIST, nmp->nullm_node_hash); 209 mutex_destroy(&nmp->nullm_hashlock); 210 kmem_free(mp->mnt_data, sizeof(struct null_mount)); 211 mp->mnt_data = NULL; 212 return 0; 213 } 214 215 extern const struct vnodeopv_desc null_vnodeop_opv_desc; 216 217 const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = { 218 &null_vnodeop_opv_desc, 219 NULL, 220 }; 221 222 struct vfsops nullfs_vfsops = { 223 .vfs_name = MOUNT_NULL, 224 .vfs_min_mount_data = sizeof (struct null_args), 225 .vfs_mount = nullfs_mount, 226 .vfs_start = layerfs_start, 227 .vfs_unmount = nullfs_unmount, 228 .vfs_root = layerfs_root, 229 .vfs_quotactl = layerfs_quotactl, 230 .vfs_statvfs = layerfs_statvfs, 231 .vfs_sync = layerfs_sync, 232 .vfs_vget = layerfs_vget, 233 .vfs_fhtovp = layerfs_fhtovp, 234 .vfs_vptofh = layerfs_vptofh, 235 .vfs_init = layerfs_init, 236 .vfs_done = layerfs_done, 237 .vfs_snapshot = layerfs_snapshot, 238 .vfs_extattrctl = vfs_stdextattrctl, 239 .vfs_suspendctl = (void *)eopnotsupp, 240 .vfs_renamelock_enter = layerfs_renamelock_enter, 241 .vfs_renamelock_exit = layerfs_renamelock_exit, 242 .vfs_fsync = (void *)eopnotsupp, 243 .vfs_opv_descs = nullfs_vnodeopv_descs 244 }; 245 246 static int 247 null_modcmd(modcmd_t cmd, void *arg) 248 { 249 int error; 250 251 switch (cmd) { 252 case MODULE_CMD_INIT: 253 error = vfs_attach(&nullfs_vfsops); 254 if (error != 0) 255 break; 256 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL, 257 CTLFLAG_PERMANENT, 258 CTLTYPE_NODE, "null", 259 SYSCTL_DESCR("Loopback file system"), 260 NULL, 0, NULL, 0, 261 CTL_VFS, 9, CTL_EOL); 262 /* 263 * XXX the "9" above could be dynamic, thereby eliminating 264 * one more instance of the "number to vfs" mapping problem, 265 * but "9" is the order as taken from sys/mount.h 266 */ 267 break; 268 case MODULE_CMD_FINI: 269 error = vfs_detach(&nullfs_vfsops); 270 if (error != 0) 271 break; 272 sysctl_teardown(&nullfs_sysctl_log); 273 break; 274 default: 275 error = ENOTTY; 276 break; 277 } 278 return error; 279 } 280
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