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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 33 * 34 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 35 * $FreeBSD: src/sys/miscfs/nullfs/null_vfsops.c,v 1.35.2.3 2001/07/26 20:37:11 iedowse Exp $ 36 * $DragonFly: src/sys/vfs/nullfs/null_vfsops.c,v 1.31 2008/09/17 21:44:25 dillon Exp $ 37 */ 38 39 /* 40 * Null Layer 41 * (See null_vnops.c for a description of what this does.) 42 */ 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kernel.h> 47 #include <sys/proc.h> 48 #include <sys/malloc.h> 49 #include <sys/vnode.h> 50 #include <sys/mount.h> 51 #include <sys/namecache.h> 52 #include <sys/nlookup.h> 53 #include <sys/mountctl.h> 54 #include "null.h" 55 56 extern struct vop_ops null_vnode_vops; 57 58 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 59 60 static int nullfs_root(struct mount *mp, struct vnode **vpp); 61 static int nullfs_statfs(struct mount *mp, struct statfs *sbp, 62 struct ucred *cred); 63 64 /* 65 * Mount null layer 66 */ 67 static int 68 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred) 69 { 70 int error = 0; 71 struct null_args args; 72 struct vnode *rootvp; 73 struct null_mount *xmp; 74 size_t size; 75 struct nlookupdata nd; 76 fhandle_t fh; 77 78 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 79 80 /* 81 * Get argument 82 */ 83 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 84 if (error) 85 return (error); 86 87 /* 88 * XXX: Should we process mount export info ? 89 * If not, returning zero here is enough as the actual ro/rw update is 90 * being done in sys_mount(). 91 */ 92 if (mp->mnt_flag & MNT_UPDATE) { 93 xmp = MOUNTTONULLMOUNT(mp); 94 error = vfs_export(mp, &xmp->export, &args.export); 95 return (error); 96 } 97 98 /* 99 * Find lower node 100 */ 101 rootvp = NULL; 102 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); 103 if (error) 104 goto fail1; 105 error = nlookup(&nd); 106 if (error) 107 goto fail2; 108 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp); 109 if (error) 110 goto fail2; 111 112 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount), 113 M_NULLFSMNT, M_WAITOK | M_ZERO); 114 115 /* 116 * Save reference to underlying FS 117 * 118 * As lite stacking enters the scene, the old way of doing this 119 * -- via the vnode -- is not good enough anymore. Use the 120 * underlying filesystem's namecache handle as our mount point 121 * root, adjusting the mount to point to us. 122 * 123 * NCF_ISMOUNTPT is normally set on the mount point, but we also 124 * want to set it on the base directory being mounted to prevent 125 * that directory from being destroyed out from under the nullfs 126 * mount. 127 * 128 * The forwarding mount pointer (xmp->nullm_vfs) must be set to 129 * the actual target filesystem. If the target filesystem was 130 * resolved via a nullfs mount nd.nl_nch.mount will be pointing 131 * to the nullfs mount structure instead of the target filesystem, 132 * which would otherwise cause the mount VOPS and VFSOPS to recurse 133 * endlessly. If we are mounting via a nullfs mount we inherit 134 * its read-only state, if set. 135 */ 136 xmp->nullm_vfs = nd.nl_nch.mount; 137 if (xmp->nullm_vfs != rootvp->v_mount) { 138 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY) 139 mp->mnt_flag |= MNT_RDONLY; 140 if (xmp->nullm_vfs->mnt_flag & MNT_NOEXEC) 141 mp->mnt_flag |= MNT_NOEXEC; 142 xmp->nullm_vfs = rootvp->v_mount; 143 } 144 145 /* 146 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs 147 * we retain the parent nullfs to create a unique chain tuple. 148 */ 149 mp->mnt_ncmountpt = nd.nl_nch; 150 cache_changemount(&mp->mnt_ncmountpt, mp); 151 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT; 152 cache_unlock(&mp->mnt_ncmountpt); 153 cache_zero(&nd.nl_nch); 154 nlookup_done(&nd); 155 156 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops); 157 158 vn_unlock(rootvp); /* leave reference intact */ 159 160 /* 161 * Keep a held reference to the root vnode. 162 * It is vrele'd in nullfs_unmount. 163 */ 164 xmp->nullm_rootvp = rootvp; 165 /* 166 * XXX What's the proper safety condition for querying 167 * the underlying mount? Is this flag tuning necessary 168 * at all? 169 */ 170 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL) 171 mp->mnt_flag |= MNT_LOCAL; 172 mp->mnt_data = (qaddr_t) xmp; 173 174 /* 175 * Try to create a unique but non-random fsid for the nullfs to 176 * allow it to be exported via NFS. 177 */ 178 bzero(&fh, sizeof(fh)); 179 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid; 180 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) { 181 fh.fh_fsid.val[1] ^= crc32(&fh.fh_fid, sizeof(fh.fh_fid)); 182 vfs_setfsid(mp, &fh.fh_fsid); 183 } else { 184 vfs_getnewfsid(mp); 185 } 186 187 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 188 &size); 189 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 190 (void)nullfs_statfs(mp, &mp->mnt_stat, cred); 191 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 192 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname); 193 194 bzero(mp->mnt_stat.f_mntonname, MNAMELEN); 195 if (path != NULL) { 196 (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, 197 &size); 198 } 199 200 /* 201 * Set NCALIASED so unmount won't complain about namecache refs 202 * still existing. 203 * 204 * All NULLFS operations are MPSAFE, though it will be short-lived 205 * if the underlying filesystem is not. 206 */ 207 mp->mnt_kern_flag |= MNTK_NCALIASED | MNTK_ALL_MPSAFE; 208 return (0); 209 fail2: 210 nlookup_done(&nd); 211 fail1: 212 return (error); 213 } 214 215 /* 216 * Free reference to null layer 217 */ 218 static int 219 nullfs_unmount(struct mount *mp, int mntflags) 220 { 221 struct null_mount *xmp; 222 223 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 224 225 /* 226 * Throw away the null_mount structure 227 */ 228 xmp = (void *)mp->mnt_data; 229 mp->mnt_data = 0; 230 if (xmp->nullm_rootvp) { 231 vrele(xmp->nullm_rootvp); 232 xmp->nullm_rootvp = NULL; 233 } 234 kfree(xmp, M_NULLFSMNT); 235 return 0; 236 } 237 238 static int 239 nullfs_root(struct mount *mp, struct vnode **vpp) 240 { 241 struct vnode *vp; 242 int error; 243 244 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp, 245 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 246 247 /* 248 * Return locked reference to root. 249 */ 250 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 251 error = vget(vp, LK_EXCLUSIVE | LK_RETRY); 252 if (error == 0) 253 *vpp = vp; 254 return (error); 255 } 256 257 static int 258 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 259 struct ucred *cred) 260 { 261 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred); 262 } 263 264 static int 265 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred) 266 { 267 int error; 268 struct statfs mstat; 269 270 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp, 271 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 272 273 bzero(&mstat, sizeof(mstat)); 274 275 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred); 276 if (error) 277 return (error); 278 279 /* now copy across the "interesting" information and fake the rest */ 280 sbp->f_type = mstat.f_type; 281 sbp->f_flags = mstat.f_flags; 282 sbp->f_bsize = mstat.f_bsize; 283 sbp->f_iosize = mstat.f_iosize; 284 sbp->f_blocks = mstat.f_blocks; 285 sbp->f_bfree = mstat.f_bfree; 286 sbp->f_bavail = mstat.f_bavail; 287 sbp->f_files = mstat.f_files; 288 sbp->f_ffree = mstat.f_ffree; 289 if (sbp != &mp->mnt_stat) { 290 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 291 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 292 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 293 } 294 return (0); 295 } 296 297 /* 298 * Implement NFS export tracking 299 */ 300 static int 301 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp, 302 struct ucred **credanonp) 303 { 304 struct null_mount *xmp = (void *)mp->mnt_data; 305 struct netcred *np; 306 int error; 307 308 np = vfs_export_lookup(mp, &xmp->export, nam); 309 if (np) { 310 *extflagsp = np->netc_exflags; 311 *credanonp = &np->netc_anon; 312 error = 0; 313 } else { 314 error = EACCES; 315 } 316 return(error); 317 #if 0 318 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 319 extflagsp, credanonp); 320 #endif 321 } 322 323 int 324 nullfs_export(struct mount *mp, int op, const struct export_args *export) 325 { 326 struct null_mount *xmp = (void *)mp->mnt_data; 327 int error; 328 329 switch(op) { 330 case MOUNTCTL_SET_EXPORT: 331 error = vfs_export(mp, &xmp->export, export); 332 break; 333 default: 334 error = EOPNOTSUPP; 335 break; 336 } 337 return(error); 338 } 339 340 /* 341 * Pass through file handle conversion functions. 342 */ 343 static int 344 nullfs_vptofh(struct vnode *vp, struct fid *fhp) 345 { 346 return VFS_VPTOFH(vp, fhp); 347 } 348 349 /* 350 * Pass through file handle conversion functions. 351 * 352 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only 353 * to enforce PFS isolation. 354 */ 355 static int 356 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp, 357 struct fid *fhp, struct vnode **vpp) 358 { 359 struct null_mount *xmp = MOUNTTONULLMOUNT(mp); 360 361 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp); 362 } 363 364 static int 365 nullfs_extattrctl(struct mount *mp, int cmd, struct vnode *vp, 366 int attrnamespace, const char *attrname, struct ucred *cred) 367 { 368 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 369 vp, attrnamespace, attrname, cred); 370 } 371 372 static void 373 nullfs_ncpgen_set(struct mount *mp, struct namecache *ncp) 374 { 375 struct null_mount *xmp = MOUNTTONULLMOUNT(mp); 376 377 VFS_NCPGEN_SET(xmp->nullm_vfs, ncp); 378 } 379 380 381 static int 382 nullfs_ncpgen_test(struct mount *mp, struct namecache *ncp) 383 { 384 struct null_mount *xmp = MOUNTTONULLMOUNT(mp); 385 386 return VFS_NCPGEN_TEST(xmp->nullm_vfs, ncp); 387 } 388 389 390 static struct vfsops null_vfsops = { 391 .vfs_mount = nullfs_mount, 392 .vfs_unmount = nullfs_unmount, 393 .vfs_root = nullfs_root, 394 .vfs_quotactl = nullfs_quotactl, 395 .vfs_statfs = nullfs_statfs, 396 .vfs_sync = vfs_stdsync, 397 .vfs_extattrctl = nullfs_extattrctl, 398 .vfs_fhtovp = nullfs_fhtovp, 399 .vfs_vptofh = nullfs_vptofh, 400 .vfs_ncpgen_set = nullfs_ncpgen_set, 401 .vfs_ncpgen_test = nullfs_ncpgen_test, 402 .vfs_checkexp = nullfs_checkexp 403 }; 404 405 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 406 MODULE_VERSION(null, 1); 407