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 1.31 2008/09/17 21:44:25 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 <sys/mountctl.h> 57 #include "null.h" 58 59 extern struct vop_ops null_vnode_vops; 60 61 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 62 63 static int nullfs_root(struct mount *mp, struct vnode **vpp); 64 static int nullfs_statfs(struct mount *mp, struct statfs *sbp, 65 struct ucred *cred); 66 67 /* 68 * Mount null layer 69 */ 70 static int 71 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred) 72 { 73 int error = 0; 74 struct null_args args; 75 struct vnode *rootvp; 76 struct null_mount *xmp; 77 size_t size; 78 struct nlookupdata nd; 79 fhandle_t fh; 80 81 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 82 83 /* 84 * Get argument 85 */ 86 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 87 if (error) 88 return (error); 89 90 /* 91 * XXX: Should we process mount export info ? 92 * If not, returning zero here is enough as the actual ro/rw update is 93 * being done in sys_mount(). 94 */ 95 if (mp->mnt_flag & MNT_UPDATE) { 96 xmp = MOUNTTONULLMOUNT(mp); 97 error = vfs_export(mp, &xmp->export, &args.export); 98 return (error); 99 } 100 101 /* 102 * Find lower node 103 */ 104 rootvp = NULL; 105 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); 106 if (error) 107 goto fail1; 108 error = nlookup(&nd); 109 if (error) 110 goto fail2; 111 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp); 112 if (error) 113 goto fail2; 114 115 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount), 116 M_NULLFSMNT, M_WAITOK | M_ZERO); 117 118 /* 119 * Save reference to underlying FS 120 * 121 * As lite stacking enters the scene, the old way of doing this 122 * -- via the vnode -- is not good enough anymore. Use the 123 * underlying filesystem's namecache handle as our mount point 124 * root, adjusting the mount to point to us. 125 * 126 * NCF_ISMOUNTPT is normally set on the mount point, but we also 127 * want to set it on the base directory being mounted to prevent 128 * that directory from being destroyed out from under the nullfs 129 * mount. 130 * 131 * The forwarding mount pointer (xmp->nullm_vfs) must be set to 132 * the actual target filesystem. If the target filesystem was 133 * resolved via a nullfs mount nd.nl_nch.mount will be pointing 134 * to the nullfs mount structure instead of the target filesystem, 135 * which would otherwise cause the mount VOPS and VFSOPS to recurse 136 * endlessly. If we are mounting via a nullfs mount we inherit 137 * its read-only state, if set. 138 */ 139 xmp->nullm_vfs = nd.nl_nch.mount; 140 if (xmp->nullm_vfs != rootvp->v_mount) { 141 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY) 142 mp->mnt_flag |= MNT_RDONLY; 143 if (xmp->nullm_vfs->mnt_flag & MNT_NOEXEC) 144 mp->mnt_flag |= MNT_NOEXEC; 145 xmp->nullm_vfs = rootvp->v_mount; 146 } 147 148 /* 149 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs 150 * we retain the parent nullfs to create a unique chain tuple. 151 */ 152 mp->mnt_ncmountpt = nd.nl_nch; 153 cache_changemount(&mp->mnt_ncmountpt, mp); 154 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT; 155 cache_unlock(&mp->mnt_ncmountpt); 156 cache_zero(&nd.nl_nch); 157 nlookup_done(&nd); 158 159 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops); 160 161 vn_unlock(rootvp); /* leave reference intact */ 162 163 /* 164 * Keep a held reference to the root vnode. 165 * It is vrele'd in nullfs_unmount. 166 */ 167 xmp->nullm_rootvp = rootvp; 168 /* 169 * XXX What's the proper safety condition for querying 170 * the underlying mount? Is this flag tuning necessary 171 * at all? 172 */ 173 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL) 174 mp->mnt_flag |= MNT_LOCAL; 175 mp->mnt_data = (qaddr_t) xmp; 176 177 /* 178 * Try to create a unique but non-random fsid for the nullfs to 179 * allow it to be exported via NFS. 180 */ 181 bzero(&fh, sizeof(fh)); 182 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid; 183 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) { 184 fh.fh_fsid.val[1] ^= crc32(&fh.fh_fid, sizeof(fh.fh_fid)); 185 vfs_setfsid(mp, &fh.fh_fsid); 186 } else { 187 vfs_getnewfsid(mp); 188 } 189 190 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 191 &size); 192 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 193 (void)nullfs_statfs(mp, &mp->mnt_stat, cred); 194 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 195 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname); 196 197 /* 198 * Set NCALIASED so unmount won't complain about namecache refs 199 * still existing. 200 * 201 * All NULLFS operations are MPSAFE, though it will be short-lived 202 * if the underlying filesystem is not. 203 */ 204 mp->mnt_kern_flag |= MNTK_NCALIASED | MNTK_ALL_MPSAFE; 205 return (0); 206 fail2: 207 nlookup_done(&nd); 208 fail1: 209 return (error); 210 } 211 212 /* 213 * Free reference to null layer 214 */ 215 static int 216 nullfs_unmount(struct mount *mp, int mntflags) 217 { 218 struct null_mount *xmp; 219 int flags = 0; 220 221 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 222 223 if (mntflags & MNT_FORCE) 224 flags |= FORCECLOSE; 225 226 /* 227 * Finally, throw away the null_mount structure 228 */ 229 xmp = (void *)mp->mnt_data; 230 mp->mnt_data = 0; 231 if (xmp->nullm_rootvp) { 232 vrele(xmp->nullm_rootvp); 233 xmp->nullm_rootvp = NULL; 234 } 235 kfree(xmp, M_NULLFSMNT); 236 return 0; 237 } 238 239 static int 240 nullfs_root(struct mount *mp, struct vnode **vpp) 241 { 242 struct vnode *vp; 243 int error; 244 245 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp, 246 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 247 248 /* 249 * Return locked reference to root. 250 */ 251 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 252 error = vget(vp, LK_EXCLUSIVE | LK_RETRY); 253 if (error == 0) 254 *vpp = vp; 255 return (error); 256 } 257 258 static int 259 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 260 struct ucred *cred) 261 { 262 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred); 263 } 264 265 static int 266 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred) 267 { 268 int error; 269 struct statfs mstat; 270 271 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp, 272 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 273 274 bzero(&mstat, sizeof(mstat)); 275 276 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred); 277 if (error) 278 return (error); 279 280 /* now copy across the "interesting" information and fake the rest */ 281 sbp->f_type = mstat.f_type; 282 sbp->f_flags = mstat.f_flags; 283 sbp->f_bsize = mstat.f_bsize; 284 sbp->f_iosize = mstat.f_iosize; 285 sbp->f_blocks = mstat.f_blocks; 286 sbp->f_bfree = mstat.f_bfree; 287 sbp->f_bavail = mstat.f_bavail; 288 sbp->f_files = mstat.f_files; 289 sbp->f_ffree = mstat.f_ffree; 290 if (sbp != &mp->mnt_stat) { 291 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 292 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, 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 } 371 372 373 static struct vfsops null_vfsops = { 374 .vfs_mount = nullfs_mount, 375 .vfs_unmount = nullfs_unmount, 376 .vfs_root = nullfs_root, 377 .vfs_quotactl = nullfs_quotactl, 378 .vfs_statfs = nullfs_statfs, 379 .vfs_sync = vfs_stdsync, 380 .vfs_extattrctl = nullfs_extattrctl, 381 .vfs_fhtovp = nullfs_fhtovp, 382 .vfs_vptofh = nullfs_vptofh, 383 .vfs_checkexp = nullfs_checkexp 384 }; 385 386 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 387