1 /* $NetBSD: null_vfsops.c,v 1.99 2020/04/13 19:23:19 ad 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 1.99 2020/04/13 19:23:19 ad 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 int 97 nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len) 98 { 99 struct vnode *lowerrootvp, *vp; 100 struct null_args *args = data; 101 struct null_mount *nmp; 102 struct layer_mount *lmp; 103 struct pathbuf *pb; 104 struct nameidata nd; 105 int error; 106 107 if (args == NULL) 108 return EINVAL; 109 if (*data_len < sizeof(*args)) 110 return EINVAL; 111 112 if (mp->mnt_flag & MNT_GETARGS) { 113 lmp = MOUNTTOLAYERMOUNT(mp); 114 if (lmp == NULL) 115 return EIO; 116 args->la.target = NULL; 117 *data_len = sizeof(*args); 118 return 0; 119 } 120 121 /* Update is not supported. */ 122 if (mp->mnt_flag & MNT_UPDATE) 123 return EOPNOTSUPP; 124 125 /* Find the lower vnode and lock it. */ 126 error = pathbuf_copyin(args->la.target, &pb); 127 if (error) { 128 return error; 129 } 130 NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb); 131 if ((error = namei(&nd)) != 0) { 132 pathbuf_destroy(pb); 133 return error; 134 } 135 lowerrootvp = nd.ni_vp; 136 pathbuf_destroy(pb); 137 138 /* Create the mount point. */ 139 nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP); 140 mp->mnt_data = nmp; 141 mp->mnt_iflag |= IMNT_MPSAFE; 142 mp->mnt_iflag |= lowerrootvp->v_mount->mnt_iflag & IMNT_SHRLOOKUP; 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 VOP_UNLOCK(vp); 172 173 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target, 174 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp); 175 if (error) 176 return error; 177 178 if (mp->mnt_lower->mnt_flag & MNT_LOCAL) 179 mp->mnt_flag |= MNT_LOCAL; 180 return 0; 181 } 182 183 int 184 nullfs_unmount(struct mount *mp, int mntflags) 185 { 186 struct null_mount *nmp = MOUNTTONULLMOUNT(mp); 187 struct vnode *null_rootvp = nmp->nullm_rootvp; 188 int error, flags = 0; 189 190 if (mntflags & MNT_FORCE) 191 flags |= FORCECLOSE; 192 193 if (vrefcnt(null_rootvp) > 1 && (mntflags & MNT_FORCE) == 0) 194 return EBUSY; 195 196 if ((error = vflush(mp, null_rootvp, flags)) != 0) 197 return error; 198 199 /* Eliminate all activity and release the vnode. */ 200 vgone(null_rootvp); 201 202 /* Finally, destroy the mount point structures. */ 203 kmem_free(mp->mnt_data, sizeof(struct null_mount)); 204 mp->mnt_data = NULL; 205 return 0; 206 } 207 208 extern const struct vnodeopv_desc null_vnodeop_opv_desc; 209 210 const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = { 211 &null_vnodeop_opv_desc, 212 NULL, 213 }; 214 215 struct vfsops nullfs_vfsops = { 216 .vfs_name = MOUNT_NULL, 217 .vfs_min_mount_data = sizeof (struct null_args), 218 .vfs_mount = nullfs_mount, 219 .vfs_start = layerfs_start, 220 .vfs_unmount = nullfs_unmount, 221 .vfs_root = layerfs_root, 222 .vfs_quotactl = layerfs_quotactl, 223 .vfs_statvfs = layerfs_statvfs, 224 .vfs_sync = layerfs_sync, 225 .vfs_loadvnode = layerfs_loadvnode, 226 .vfs_vget = layerfs_vget, 227 .vfs_fhtovp = layerfs_fhtovp, 228 .vfs_vptofh = layerfs_vptofh, 229 .vfs_init = layerfs_init, 230 .vfs_done = layerfs_done, 231 .vfs_snapshot = layerfs_snapshot, 232 .vfs_extattrctl = vfs_stdextattrctl, 233 .vfs_suspendctl = layerfs_suspendctl, 234 .vfs_renamelock_enter = layerfs_renamelock_enter, 235 .vfs_renamelock_exit = layerfs_renamelock_exit, 236 .vfs_fsync = (void *)eopnotsupp, 237 .vfs_opv_descs = nullfs_vnodeopv_descs 238 }; 239 240 SYSCTL_SETUP(nullfs_sysctl_setup, "nullfs sysctl") 241 { 242 243 sysctl_createv(clog, 0, NULL, NULL, 244 CTLFLAG_PERMANENT, 245 CTLTYPE_NODE, "null", 246 SYSCTL_DESCR("Loopback file system"), 247 NULL, 0, NULL, 0, 248 CTL_VFS, 9, CTL_EOL); 249 /* 250 * XXX the "9" above could be dynamic, thereby eliminating 251 * one more instance of the "number to vfs" mapping problem, 252 * but "9" is the order as taken from sys/mount.h 253 */ 254 } 255 256 static int 257 null_modcmd(modcmd_t cmd, void *arg) 258 { 259 int error; 260 261 switch (cmd) { 262 case MODULE_CMD_INIT: 263 error = vfs_attach(&nullfs_vfsops); 264 if (error != 0) 265 break; 266 break; 267 case MODULE_CMD_FINI: 268 error = vfs_detach(&nullfs_vfsops); 269 if (error != 0) 270 break; 271 break; 272 default: 273 error = ENOTTY; 274 break; 275 } 276 return error; 277 } 278