1 /* $NetBSD: null_vfsops.c,v 1.101 2023/02/06 10:32:58 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 1.101 2023/02/06 10:32:58 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 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 |= lowerrootvp->v_mount->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 error = vfs_set_lowermount(mp, lowerrootvp->v_mount); 150 if (error) { 151 vput(lowerrootvp); 152 kmem_free(nmp, sizeof(struct null_mount)); 153 return error; 154 } 155 156 nmp->nullm_size = sizeof(struct null_node); 157 nmp->nullm_tag = VT_NULL; 158 nmp->nullm_bypass = layer_bypass; 159 nmp->nullm_vnodeop_p = null_vnodeop_p; 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 kmem_free(nmp, sizeof(struct null_mount)); 167 return error; 168 } 169 /* 170 * Keep a held reference to the root vnode. It will be released on 171 * umount. Note: nullfs is MP-safe. 172 */ 173 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 174 vp->v_vflag |= VV_ROOT; 175 nmp->nullm_rootvp = vp; 176 VOP_UNLOCK(vp); 177 178 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target, 179 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp); 180 if (error) 181 return error; 182 183 if (mp->mnt_lower->mnt_flag & MNT_LOCAL) 184 mp->mnt_flag |= MNT_LOCAL; 185 return 0; 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 (vrefcnt(null_rootvp) > 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 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 .vfs_name = MOUNT_NULL, 222 .vfs_min_mount_data = sizeof (struct null_args), 223 .vfs_mount = nullfs_mount, 224 .vfs_start = layerfs_start, 225 .vfs_unmount = nullfs_unmount, 226 .vfs_root = layerfs_root, 227 .vfs_quotactl = layerfs_quotactl, 228 .vfs_statvfs = layerfs_statvfs, 229 .vfs_sync = layerfs_sync, 230 .vfs_loadvnode = layerfs_loadvnode, 231 .vfs_vget = layerfs_vget, 232 .vfs_fhtovp = layerfs_fhtovp, 233 .vfs_vptofh = layerfs_vptofh, 234 .vfs_init = layerfs_init, 235 .vfs_done = layerfs_done, 236 .vfs_snapshot = layerfs_snapshot, 237 .vfs_extattrctl = vfs_stdextattrctl, 238 .vfs_suspendctl = layerfs_suspendctl, 239 .vfs_renamelock_enter = layerfs_renamelock_enter, 240 .vfs_renamelock_exit = layerfs_renamelock_exit, 241 .vfs_fsync = (void *)eopnotsupp, 242 .vfs_opv_descs = nullfs_vnodeopv_descs 243 }; 244 245 SYSCTL_SETUP(nullfs_sysctl_setup, "nullfs sysctl") 246 { 247 248 sysctl_createv(clog, 0, NULL, NULL, 249 CTLFLAG_PERMANENT, 250 CTLTYPE_NODE, "null", 251 SYSCTL_DESCR("Loopback file system"), 252 NULL, 0, NULL, 0, 253 CTL_VFS, 9, CTL_EOL); 254 /* 255 * XXX the "9" above could be dynamic, thereby eliminating 256 * one more instance of the "number to vfs" mapping problem, 257 * but "9" is the order as taken from sys/mount.h 258 */ 259 } 260 261 static int 262 null_modcmd(modcmd_t cmd, void *arg) 263 { 264 int error; 265 266 switch (cmd) { 267 case MODULE_CMD_INIT: 268 error = vfs_attach(&nullfs_vfsops); 269 if (error != 0) 270 break; 271 break; 272 case MODULE_CMD_FINI: 273 error = vfs_detach(&nullfs_vfsops); 274 if (error != 0) 275 break; 276 break; 277 default: 278 error = ENOTTY; 279 break; 280 } 281 return error; 282 } 283
Indexes created Sun Sep 21 15:09:59 GMT 2025