null_vfsops.c revision 1.85
1 /* $NetBSD: null_vfsops.c,v 1.85 2014/02/10 11:23:14 hannken 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 1.85 2014/02/10 11:23:14 hannken 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 (*data_len < sizeof(*args)) 111 return EINVAL; 112 113 if (mp->mnt_flag & MNT_GETARGS) { 114 lmp = MOUNTTOLAYERMOUNT(mp); 115 if (lmp == NULL) 116 return EIO; 117 args->la.target = NULL; 118 *data_len = sizeof(*args); 119 return 0; 120 } 121 122 /* Update is not supported. */ 123 if (mp->mnt_flag & MNT_UPDATE) 124 return EOPNOTSUPP; 125 126 /* Find the lower vnode and lock it. */ 127 error = pathbuf_copyin(args->la.target, &pb); 128 if (error) { 129 return error; 130 } 131 NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb); 132 if ((error = namei(&nd)) != 0) { 133 pathbuf_destroy(pb); 134 return error; 135 } 136 lowerrootvp = nd.ni_vp; 137 pathbuf_destroy(pb); 138 139 /* Create the mount point. */ 140 nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP); 141 mp->mnt_data = nmp; 142 nmp->nullm_vfs = lowerrootvp->v_mount; 143 if (nmp->nullm_vfs->mnt_flag & MNT_LOCAL) 144 mp->mnt_flag |= MNT_LOCAL; 145 146 /* 147 * Make sure that the mount point is sufficiently initialized 148 * that the node create call will work. 149 */ 150 vfs_getnewfsid(mp); 151 152 nmp->nullm_size = sizeof(struct null_node); 153 nmp->nullm_tag = VT_NULL; 154 nmp->nullm_bypass = layer_bypass; 155 nmp->nullm_alloc = layer_node_alloc; /* the default alloc is fine */ 156 nmp->nullm_vnodeop_p = null_vnodeop_p; 157 mutex_init(&nmp->nullm_hashlock, MUTEX_DEFAULT, IPL_NONE); 158 nmp->nullm_node_hashtbl = hashinit(desiredvnodes, HASH_LIST, true, 159 &nmp->nullm_node_hash); 160 161 /* Setup a null node for root vnode. */ 162 VOP_UNLOCK(lowerrootvp); 163 error = layer_node_create(mp, lowerrootvp, &vp); 164 if (error) { 165 vrele(lowerrootvp); 166 hashdone(nmp->nullm_node_hashtbl, HASH_LIST, 167 nmp->nullm_node_hash); 168 kmem_free(nmp, sizeof(struct null_mount)); 169 return error; 170 } 171 /* 172 * Keep a held reference to the root vnode. It will be released on 173 * umount. Note: nullfs is MP-safe. 174 */ 175 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 176 vp->v_vflag |= VV_ROOT; 177 nmp->nullm_rootvp = vp; 178 mp->mnt_iflag |= IMNT_MPSAFE; 179 VOP_UNLOCK(vp); 180 181 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target, 182 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp); 183 return error; 184 } 185 186 int 187 nullfs_unmount(struct mount *mp, int mntflags) 188 { 189 struct null_mount *nmp = MOUNTTONULLMOUNT(mp); 190 struct vnode *null_rootvp = nmp->nullm_rootvp; 191 int error, flags = 0; 192 193 if (mntflags & MNT_FORCE) 194 flags |= FORCECLOSE; 195 196 if (null_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0) 197 return EBUSY; 198 199 if ((error = vflush(mp, null_rootvp, flags)) != 0) 200 return error; 201 202 /* Eliminate all activity and release the vnode. */ 203 vgone(null_rootvp); 204 205 /* Finally, destroy the mount point structures. */ 206 hashdone(nmp->nullm_node_hashtbl, HASH_LIST, nmp->nullm_node_hash); 207 mutex_destroy(&nmp->nullm_hashlock); 208 kmem_free(mp->mnt_data, sizeof(struct null_mount)); 209 mp->mnt_data = NULL; 210 return 0; 211 } 212 213 extern const struct vnodeopv_desc null_vnodeop_opv_desc; 214 215 const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = { 216 &null_vnodeop_opv_desc, 217 NULL, 218 }; 219 220 struct vfsops nullfs_vfsops = { 221 MOUNT_NULL, 222 sizeof (struct null_args), 223 nullfs_mount, 224 layerfs_start, 225 nullfs_unmount, 226 layerfs_root, 227 layerfs_quotactl, 228 layerfs_statvfs, 229 layerfs_sync, 230 layerfs_vget, 231 layerfs_fhtovp, 232 layerfs_vptofh, 233 layerfs_init, 234 NULL, 235 layerfs_done, 236 NULL, /* vfs_mountroot */ 237 layerfs_snapshot, 238 vfs_stdextattrctl, 239 (void *)eopnotsupp, /* vfs_suspendctl */ 240 layerfs_renamelock_enter, 241 layerfs_renamelock_exit, 242 (void *)eopnotsupp, 243 nullfs_vnodeopv_descs, 244 0, 245 { NULL, NULL }, 246 }; 247 248 static int 249 null_modcmd(modcmd_t cmd, void *arg) 250 { 251 int error; 252 253 switch (cmd) { 254 case MODULE_CMD_INIT: 255 error = vfs_attach(&nullfs_vfsops); 256 if (error != 0) 257 break; 258 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL, 259 CTLFLAG_PERMANENT, 260 CTLTYPE_NODE, "vfs", NULL, 261 NULL, 0, NULL, 0, 262 CTL_VFS, CTL_EOL); 263 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL, 264 CTLFLAG_PERMANENT, 265 CTLTYPE_NODE, "null", 266 SYSCTL_DESCR("Loopback file system"), 267 NULL, 0, NULL, 0, 268 CTL_VFS, 9, CTL_EOL); 269 /* 270 * XXX the "9" above could be dynamic, thereby eliminating 271 * one more instance of the "number to vfs" mapping problem, 272 * but "9" is the order as taken from sys/mount.h 273 */ 274 break; 275 case MODULE_CMD_FINI: 276 error = vfs_detach(&nullfs_vfsops); 277 if (error != 0) 278 break; 279 sysctl_teardown(&nullfs_sysctl_log); 280 break; 281 default: 282 error = ENOTTY; 283 break; 284 } 285 return error; 286 } 287
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