1 /* $NetBSD: null_vfsops.c,v 1.95 2019/02/20 10:06:00 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 1.95 2019/02/20 10:06:00 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/module.h> 88 89 #include <miscfs/nullfs/null.h> 90 #include <miscfs/genfs/layer_extern.h> 91 92 MODULE(MODULE_CLASS_VFS, null, "layerfs"); 93 94 VFS_PROTOS(nullfs); 95 96 static struct sysctllog *nullfs_sysctl_log; 97 98 int 99 nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len) 100 { 101 struct vnode *lowerrootvp, *vp; 102 struct null_args *args = data; 103 struct null_mount *nmp; 104 struct layer_mount *lmp; 105 struct pathbuf *pb; 106 struct nameidata nd; 107 int error; 108 109 if (args == NULL) 110 return EINVAL; 111 if (*data_len < sizeof(*args)) 112 return EINVAL; 113 114 if (mp->mnt_flag & MNT_GETARGS) { 115 lmp = MOUNTTOLAYERMOUNT(mp); 116 if (lmp == NULL) 117 return EIO; 118 args->la.target = NULL; 119 *data_len = sizeof(*args); 120 return 0; 121 } 122 123 /* Update is not supported. */ 124 if (mp->mnt_flag & MNT_UPDATE) 125 return EOPNOTSUPP; 126 127 /* Find the lower vnode and lock it. */ 128 error = pathbuf_copyin(args->la.target, &pb); 129 if (error) { 130 return error; 131 } 132 NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb); 133 if ((error = namei(&nd)) != 0) { 134 pathbuf_destroy(pb); 135 return error; 136 } 137 lowerrootvp = nd.ni_vp; 138 pathbuf_destroy(pb); 139 140 /* Create the mount point. */ 141 nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP); 142 mp->mnt_data = nmp; 143 144 /* 145 * Make sure that the mount point is sufficiently initialized 146 * that the node create call will work. 147 */ 148 vfs_getnewfsid(mp); 149 mp->mnt_lower = lowerrootvp->v_mount; 150 151 nmp->nullm_size = sizeof(struct null_node); 152 nmp->nullm_tag = VT_NULL; 153 nmp->nullm_bypass = layer_bypass; 154 nmp->nullm_vnodeop_p = null_vnodeop_p; 155 156 /* Setup a null node for root vnode. */ 157 VOP_UNLOCK(lowerrootvp); 158 error = layer_node_create(mp, lowerrootvp, &vp); 159 if (error) { 160 vrele(lowerrootvp); 161 kmem_free(nmp, sizeof(struct null_mount)); 162 return error; 163 } 164 /* 165 * Keep a held reference to the root vnode. It will be released on 166 * umount. Note: nullfs is MP-safe. 167 */ 168 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 169 vp->v_vflag |= VV_ROOT; 170 nmp->nullm_rootvp = vp; 171 mp->mnt_iflag |= IMNT_MPSAFE; 172 VOP_UNLOCK(vp); 173 174 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target, 175 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp); 176 if (error) 177 return error; 178 179 if (mp->mnt_lower->mnt_flag & MNT_LOCAL) 180 mp->mnt_flag |= MNT_LOCAL; 181 return 0; 182 } 183 184 int 185 nullfs_unmount(struct mount *mp, int mntflags) 186 { 187 struct null_mount *nmp = MOUNTTONULLMOUNT(mp); 188 struct vnode *null_rootvp = nmp->nullm_rootvp; 189 int error, flags = 0; 190 191 if (mntflags & MNT_FORCE) 192 flags |= FORCECLOSE; 193 194 if (null_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0) 195 return EBUSY; 196 197 if ((error = vflush(mp, null_rootvp, flags)) != 0) 198 return error; 199 200 /* Eliminate all activity and release the vnode. */ 201 vgone(null_rootvp); 202 203 /* Finally, destroy the mount point structures. */ 204 kmem_free(mp->mnt_data, sizeof(struct null_mount)); 205 mp->mnt_data = NULL; 206 return 0; 207 } 208 209 extern const struct vnodeopv_desc null_vnodeop_opv_desc; 210 211 const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = { 212 &null_vnodeop_opv_desc, 213 NULL, 214 }; 215 216 struct vfsops nullfs_vfsops = { 217 .vfs_name = MOUNT_NULL, 218 .vfs_min_mount_data = sizeof (struct null_args), 219 .vfs_mount = nullfs_mount, 220 .vfs_start = layerfs_start, 221 .vfs_unmount = nullfs_unmount, 222 .vfs_root = layerfs_root, 223 .vfs_quotactl = layerfs_quotactl, 224 .vfs_statvfs = layerfs_statvfs, 225 .vfs_sync = layerfs_sync, 226 .vfs_loadvnode = layerfs_loadvnode, 227 .vfs_vget = layerfs_vget, 228 .vfs_fhtovp = layerfs_fhtovp, 229 .vfs_vptofh = layerfs_vptofh, 230 .vfs_init = layerfs_init, 231 .vfs_done = layerfs_done, 232 .vfs_snapshot = layerfs_snapshot, 233 .vfs_extattrctl = vfs_stdextattrctl, 234 .vfs_suspendctl = layerfs_suspendctl, 235 .vfs_renamelock_enter = layerfs_renamelock_enter, 236 .vfs_renamelock_exit = layerfs_renamelock_exit, 237 .vfs_fsync = (void *)eopnotsupp, 238 .vfs_opv_descs = nullfs_vnodeopv_descs 239 }; 240 241 static int 242 null_modcmd(modcmd_t cmd, void *arg) 243 { 244 int error; 245 246 switch (cmd) { 247 case MODULE_CMD_INIT: 248 error = vfs_attach(&nullfs_vfsops); 249 if (error != 0) 250 break; 251 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL, 252 CTLFLAG_PERMANENT, 253 CTLTYPE_NODE, "null", 254 SYSCTL_DESCR("Loopback file system"), 255 NULL, 0, NULL, 0, 256 CTL_VFS, 9, CTL_EOL); 257 /* 258 * XXX the "9" above could be dynamic, thereby eliminating 259 * one more instance of the "number to vfs" mapping problem, 260 * but "9" is the order as taken from sys/mount.h 261 */ 262 break; 263 case MODULE_CMD_FINI: 264 error = vfs_detach(&nullfs_vfsops); 265 if (error != 0) 266 break; 267 sysctl_teardown(&nullfs_sysctl_log); 268 break; 269 default: 270 error = ENOTTY; 271 break; 272 } 273 return error; 274 } 275