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; 219 220 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 221 222 /* 223 * Throw away the null_mount structure 224 */ 225 xmp = (void *)mp->mnt_data; 226 mp->mnt_data = 0; 227 if (xmp->nullm_rootvp) { 228 vrele(xmp->nullm_rootvp); 229 xmp->nullm_rootvp = NULL; 230 } 231 kfree(xmp, M_NULLFSMNT); 232 return 0; 233 } 234 235 static int 236 nullfs_root(struct mount *mp, struct vnode **vpp) 237 { 238 struct vnode *vp; 239 int error; 240 241 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp, 242 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 243 244 /* 245 * Return locked reference to root. 246 */ 247 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 248 error = vget(vp, LK_EXCLUSIVE | LK_RETRY); 249 if (error == 0) 250 *vpp = vp; 251 return (error); 252 } 253 254 static int 255 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 256 struct ucred *cred) 257 { 258 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred); 259 } 260 261 static int 262 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred) 263 { 264 int error; 265 struct statfs mstat; 266 267 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp, 268 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 269 270 bzero(&mstat, sizeof(mstat)); 271 272 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred); 273 if (error) 274 return (error); 275 276 /* now copy across the "interesting" information and fake the rest */ 277 sbp->f_type = mstat.f_type; 278 sbp->f_flags = mstat.f_flags; 279 sbp->f_bsize = mstat.f_bsize; 280 sbp->f_iosize = mstat.f_iosize; 281 sbp->f_blocks = mstat.f_blocks; 282 sbp->f_bfree = mstat.f_bfree; 283 sbp->f_bavail = mstat.f_bavail; 284 sbp->f_files = mstat.f_files; 285 sbp->f_ffree = mstat.f_ffree; 286 if (sbp != &mp->mnt_stat) { 287 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 288 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 289 } 290 return (0); 291 } 292 293 /* 294 * Implement NFS export tracking 295 */ 296 static int 297 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp, 298 struct ucred **credanonp) 299 { 300 struct null_mount *xmp = (void *)mp->mnt_data; 301 struct netcred *np; 302 int error; 303 304 np = vfs_export_lookup(mp, &xmp->export, nam); 305 if (np) { 306 *extflagsp = np->netc_exflags; 307 *credanonp = &np->netc_anon; 308 error = 0; 309 } else { 310 error = EACCES; 311 } 312 return(error); 313 #if 0 314 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 315 extflagsp, credanonp); 316 #endif 317 } 318 319 int 320 nullfs_export(struct mount *mp, int op, const struct export_args *export) 321 { 322 struct null_mount *xmp = (void *)mp->mnt_data; 323 int error; 324 325 switch(op) { 326 case MOUNTCTL_SET_EXPORT: 327 error = vfs_export(mp, &xmp->export, export); 328 break; 329 default: 330 error = EOPNOTSUPP; 331 break; 332 } 333 return(error); 334 } 335 336 /* 337 * Pass through file handle conversion functions. 338 */ 339 static int 340 nullfs_vptofh(struct vnode *vp, struct fid *fhp) 341 { 342 return VFS_VPTOFH(vp, fhp); 343 } 344 345 /* 346 * Pass through file handle conversion functions. 347 * 348 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only 349 * to enforce PFS isolation. 350 */ 351 static int 352 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp, 353 struct fid *fhp, struct vnode **vpp) 354 { 355 struct null_mount *xmp = MOUNTTONULLMOUNT(mp); 356 357 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp); 358 } 359 360 static int 361 nullfs_extattrctl(struct mount *mp, int cmd, struct vnode *vp, 362 int attrnamespace, const char *attrname, struct ucred *cred) 363 { 364 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 365 vp, attrnamespace, attrname, cred); 366 } 367 368 369 static struct vfsops null_vfsops = { 370 .vfs_mount = nullfs_mount, 371 .vfs_unmount = nullfs_unmount, 372 .vfs_root = nullfs_root, 373 .vfs_quotactl = nullfs_quotactl, 374 .vfs_statfs = nullfs_statfs, 375 .vfs_sync = vfs_stdsync, 376 .vfs_extattrctl = nullfs_extattrctl, 377 .vfs_fhtovp = nullfs_fhtovp, 378 .vfs_vptofh = nullfs_vptofh, 379 .vfs_checkexp = nullfs_checkexp 380 }; 381 382 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 383