1 /* 2 * Copyright (c) 1992, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software donated to Berkeley by 6 * Jan-Simon Pendry. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 37 * 38 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 39 * $FreeBSD: src/sys/miscfs/nullfs/null_vfsops.c,v 1.35.2.3 2001/07/26 20:37:11 iedowse Exp $ 40 * $DragonFly: src/sys/vfs/nullfs/null_vfsops.c,v 1.29 2006/10/27 04:56:34 dillon Exp $ 41 */ 42 43 /* 44 * Null Layer 45 * (See null_vnops.c for a description of what this does.) 46 */ 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/kernel.h> 51 #include <sys/proc.h> 52 #include <sys/malloc.h> 53 #include <sys/vnode.h> 54 #include <sys/mount.h> 55 #include <sys/nlookup.h> 56 #include "null.h" 57 58 extern struct vop_ops null_vnode_vops; 59 60 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 61 62 static int nullfs_root(struct mount *mp, struct vnode **vpp); 63 static int nullfs_statfs(struct mount *mp, struct statfs *sbp, 64 struct ucred *cred); 65 66 /* 67 * Mount null layer 68 */ 69 static int 70 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred) 71 { 72 int error = 0; 73 struct null_args args; 74 struct vnode *rootvp; 75 struct null_mount *xmp; 76 u_int size; 77 struct nlookupdata nd; 78 79 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 80 81 /* 82 * Update is a no-op 83 */ 84 if (mp->mnt_flag & MNT_UPDATE) { 85 return (EOPNOTSUPP); 86 } 87 88 /* 89 * Get argument 90 */ 91 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 92 if (error) 93 return (error); 94 95 /* 96 * Find lower node 97 */ 98 rootvp = NULL; 99 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); 100 if (error) 101 goto fail1; 102 error = nlookup(&nd); 103 if (error) 104 goto fail2; 105 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp); 106 if (error) 107 goto fail2; 108 109 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount), 110 M_NULLFSMNT, M_WAITOK); /* XXX */ 111 112 /* 113 * Save reference to underlying FS 114 * 115 * As lite stacking enters the scene, the old way of doing this 116 * -- via the vnode -- is not good enough anymore. Use the 117 * underlying filesystem's namecache handle as our mount point 118 * root, adjusting the mount to point to us. 119 * 120 * NCF_ISMOUNTPT is normally set on the mount point, but we also 121 * want to set it on the base directory being mounted to prevent 122 * that directory from being destroyed out from under the nullfs 123 * mount. 124 */ 125 xmp->nullm_vfs = nd.nl_nch.mount; 126 mp->mnt_ncmountpt = nd.nl_nch; 127 cache_changemount(&mp->mnt_ncmountpt, mp); 128 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT; 129 cache_unlock(&mp->mnt_ncmountpt); 130 cache_zero(&nd.nl_nch); 131 nlookup_done(&nd); 132 133 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops); 134 135 vn_unlock(rootvp); /* leave reference intact */ 136 137 /* 138 * Keep a held reference to the root vnode. 139 * It is vrele'd in nullfs_unmount. 140 */ 141 xmp->nullm_rootvp = rootvp; 142 /* 143 * XXX What's the proper safety condition for querying 144 * the underlying mount? Is this flag tuning necessary 145 * at all? 146 */ 147 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL) 148 mp->mnt_flag |= MNT_LOCAL; 149 mp->mnt_data = (qaddr_t) xmp; 150 vfs_getnewfsid(mp); 151 152 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 153 &size); 154 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 155 (void)nullfs_statfs(mp, &mp->mnt_stat, cred); 156 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 157 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname); 158 159 /* 160 * So unmount won't complain about namecache refs still existing 161 */ 162 mp->mnt_kern_flag |= MNTK_NCALIASED; 163 return (0); 164 fail2: 165 nlookup_done(&nd); 166 fail1: 167 return (error); 168 } 169 170 /* 171 * Free reference to null layer 172 */ 173 static int 174 nullfs_unmount(struct mount *mp, int mntflags) 175 { 176 struct null_mount *xmp; 177 int flags = 0; 178 179 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 180 181 if (mntflags & MNT_FORCE) 182 flags |= FORCECLOSE; 183 184 /* 185 * Finally, throw away the null_mount structure 186 */ 187 xmp = (void *)mp->mnt_data; 188 mp->mnt_data = 0; 189 if (xmp->nullm_rootvp) { 190 vrele(xmp->nullm_rootvp); 191 xmp->nullm_rootvp = NULL; 192 } 193 kfree(xmp, M_NULLFSMNT); 194 return 0; 195 } 196 197 static int 198 nullfs_root(struct mount *mp, struct vnode **vpp) 199 { 200 struct vnode *vp; 201 int error; 202 203 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp, 204 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 205 206 /* 207 * Return locked reference to root. 208 */ 209 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 210 error = vget(vp, LK_EXCLUSIVE | LK_RETRY); 211 if (error == 0) 212 *vpp = vp; 213 return (error); 214 } 215 216 static int 217 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 218 struct ucred *cred) 219 { 220 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred); 221 } 222 223 static int 224 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred) 225 { 226 int error; 227 struct statfs mstat; 228 229 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp, 230 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 231 232 bzero(&mstat, sizeof(mstat)); 233 234 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred); 235 if (error) 236 return (error); 237 238 /* now copy across the "interesting" information and fake the rest */ 239 sbp->f_type = mstat.f_type; 240 sbp->f_flags = mstat.f_flags; 241 sbp->f_bsize = mstat.f_bsize; 242 sbp->f_iosize = mstat.f_iosize; 243 sbp->f_blocks = mstat.f_blocks; 244 sbp->f_bfree = mstat.f_bfree; 245 sbp->f_bavail = mstat.f_bavail; 246 sbp->f_files = mstat.f_files; 247 sbp->f_ffree = mstat.f_ffree; 248 if (sbp != &mp->mnt_stat) { 249 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 250 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 251 } 252 return (0); 253 } 254 255 static int 256 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp, 257 struct ucred **credanonp) 258 { 259 260 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 261 extflagsp, credanonp); 262 } 263 264 static int 265 nullfs_extattrctl(struct mount *mp, int cmd, const char *attrname, caddr_t arg, 266 struct ucred *cred) 267 { 268 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname, 269 arg, cred); 270 } 271 272 273 static struct vfsops null_vfsops = { 274 .vfs_mount = nullfs_mount, 275 .vfs_unmount = nullfs_unmount, 276 .vfs_root = nullfs_root, 277 .vfs_quotactl = nullfs_quotactl, 278 .vfs_statfs = nullfs_statfs, 279 .vfs_sync = vfs_stdsync, 280 .vfs_checkexp = nullfs_checkexp, 281 .vfs_extattrctl = nullfs_extattrctl 282 }; 283 284 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 285