1 /* $NetBSD: union_vfsops.c,v 1.4 2003/04/16 21:44:20 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1994 The Regents of the University of California. 5 * Copyright (c) 1994 Jan-Simon Pendry. 6 * All rights reserved. 7 * 8 * This code is derived from software donated to Berkeley by 9 * Jan-Simon Pendry. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95 40 */ 41 42 /* 43 * Union Layer 44 */ 45 46 #include <sys/cdefs.h> 47 __KERNEL_RCSID(0, "$NetBSD: union_vfsops.c,v 1.4 2003/04/16 21:44:20 christos Exp $"); 48 49 #include <sys/param.h> 50 #include <sys/systm.h> 51 #include <sys/time.h> 52 #include <sys/proc.h> 53 #include <sys/vnode.h> 54 #include <sys/mount.h> 55 #include <sys/namei.h> 56 #include <sys/malloc.h> 57 #include <sys/filedesc.h> 58 #include <sys/queue.h> 59 #include <sys/stat.h> 60 61 #include <fs/union/union.h> 62 63 int union_mount __P((struct mount *, const char *, void *, struct nameidata *, 64 struct proc *)); 65 int union_start __P((struct mount *, int, struct proc *)); 66 int union_unmount __P((struct mount *, int, struct proc *)); 67 int union_root __P((struct mount *, struct vnode **)); 68 int union_quotactl __P((struct mount *, int, uid_t, caddr_t, struct proc *)); 69 int union_statfs __P((struct mount *, struct statfs *, struct proc *)); 70 int union_sync __P((struct mount *, int, struct ucred *, struct proc *)); 71 int union_vget __P((struct mount *, ino_t, struct vnode **)); 72 int union_fhtovp __P((struct mount *, struct fid *, struct vnode **)); 73 int union_checkexp __P((struct mount *, struct mbuf *, int *, 74 struct ucred **)); 75 int union_vptofh __P((struct vnode *, struct fid *)); 76 int union_sysctl __P((int *, u_int, void *, size_t *, void *, size_t, 77 struct proc *)); 78 79 /* 80 * Mount union filesystem 81 */ 82 int 83 union_mount(mp, path, data, ndp, p) 84 struct mount *mp; 85 const char *path; 86 void *data; 87 struct nameidata *ndp; 88 struct proc *p; 89 { 90 int error = 0; 91 struct union_args args; 92 struct vnode *lowerrootvp = NULLVP; 93 struct vnode *upperrootvp = NULLVP; 94 struct union_mount *um = 0; 95 struct ucred *cred = 0; 96 char *cp; 97 int len; 98 size_t size; 99 100 #ifdef UNION_DIAGNOSTIC 101 printf("union_mount(mp = %p)\n", mp); 102 #endif 103 104 if (mp->mnt_flag & MNT_GETARGS) { 105 um = MOUNTTOUNIONMOUNT(mp); 106 if (um == NULL) 107 return EIO; 108 args.target = NULL; 109 args.mntflags = um->um_op; 110 return copyout(&args, data, sizeof(args)); 111 } 112 /* 113 * Update is a no-op 114 */ 115 if (mp->mnt_flag & MNT_UPDATE) { 116 /* 117 * Need to provide. 118 * 1. a way to convert between rdonly and rdwr mounts. 119 * 2. support for nfs exports. 120 */ 121 error = EOPNOTSUPP; 122 goto bad; 123 } 124 125 /* 126 * Get argument 127 */ 128 error = copyin(data, (caddr_t)&args, sizeof(struct union_args)); 129 if (error) 130 goto bad; 131 132 lowerrootvp = mp->mnt_vnodecovered; 133 VREF(lowerrootvp); 134 135 /* 136 * Find upper node. 137 */ 138 NDINIT(ndp, LOOKUP, FOLLOW, 139 UIO_USERSPACE, args.target, p); 140 141 if ((error = namei(ndp)) != 0) 142 goto bad; 143 144 upperrootvp = ndp->ni_vp; 145 146 if (upperrootvp->v_type != VDIR) { 147 error = EINVAL; 148 goto bad; 149 } 150 151 um = (struct union_mount *) malloc(sizeof(struct union_mount), 152 M_UFSMNT, M_WAITOK); /* XXX */ 153 154 /* 155 * Keep a held reference to the target vnodes. 156 * They are vrele'd in union_unmount. 157 * 158 * Depending on the _BELOW flag, the filesystems are 159 * viewed in a different order. In effect, this is the 160 * same as providing a mount under option to the mount syscall. 161 */ 162 163 um->um_op = args.mntflags & UNMNT_OPMASK; 164 switch (um->um_op) { 165 case UNMNT_ABOVE: 166 um->um_lowervp = lowerrootvp; 167 um->um_uppervp = upperrootvp; 168 break; 169 170 case UNMNT_BELOW: 171 um->um_lowervp = upperrootvp; 172 um->um_uppervp = lowerrootvp; 173 break; 174 175 case UNMNT_REPLACE: 176 vrele(lowerrootvp); 177 lowerrootvp = NULLVP; 178 um->um_uppervp = upperrootvp; 179 um->um_lowervp = lowerrootvp; 180 break; 181 182 default: 183 error = EINVAL; 184 goto bad; 185 } 186 187 /* 188 * Unless the mount is readonly, ensure that the top layer 189 * supports whiteout operations 190 */ 191 if ((mp->mnt_flag & MNT_RDONLY) == 0) { 192 error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP); 193 if (error) 194 goto bad; 195 } 196 197 um->um_cred = p->p_ucred; 198 crhold(um->um_cred); 199 um->um_cmode = UN_DIRMODE &~ p->p_cwdi->cwdi_cmask; 200 201 /* 202 * Depending on what you think the MNT_LOCAL flag might mean, 203 * you may want the && to be || on the conditional below. 204 * At the moment it has been defined that the filesystem is 205 * only local if it is all local, ie the MNT_LOCAL flag implies 206 * that the entire namespace is local. If you think the MNT_LOCAL 207 * flag implies that some of the files might be stored locally 208 * then you will want to change the conditional. 209 */ 210 if (um->um_op == UNMNT_ABOVE) { 211 if (((um->um_lowervp == NULLVP) || 212 (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) && 213 (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL)) 214 mp->mnt_flag |= MNT_LOCAL; 215 } 216 217 /* 218 * Copy in the upper layer's RDONLY flag. This is for the benefit 219 * of lookup() which explicitly checks the flag, rather than asking 220 * the filesystem for it's own opinion. This means, that an update 221 * mount of the underlying filesystem to go from rdonly to rdwr 222 * will leave the unioned view as read-only. 223 */ 224 mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY); 225 226 mp->mnt_data = um; 227 vfs_getnewfsid(mp); 228 229 error = set_statfs_info( path, UIO_USERSPACE, NULL, UIO_USERSPACE, 230 mp, p); 231 if (error) 232 goto bad; 233 234 switch (um->um_op) { 235 case UNMNT_ABOVE: 236 cp = "<above>:"; 237 break; 238 case UNMNT_BELOW: 239 cp = "<below>:"; 240 break; 241 case UNMNT_REPLACE: 242 cp = ""; 243 break; 244 default: 245 cp = "<invalid>:"; 246 #ifdef DIAGNOSTIC 247 panic("union_mount: bad um_op"); 248 #endif 249 break; 250 } 251 len = strlen(cp); 252 memcpy(mp->mnt_stat.f_mntfromname, cp, len); 253 254 cp = mp->mnt_stat.f_mntfromname + len; 255 len = MNAMELEN - len; 256 257 (void) copyinstr(args.target, cp, len - 1, &size); 258 memset(cp + size, 0, len - size); 259 260 #ifdef UNION_DIAGNOSTIC 261 printf("union_mount: from %s, on %s\n", 262 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 263 #endif 264 265 /* Setup the readdir hook if it's not set already */ 266 if (!vn_union_readdir_hook) 267 vn_union_readdir_hook = union_readdirhook; 268 269 return (0); 270 271 bad: 272 if (um) 273 free(um, M_UFSMNT); 274 if (cred) 275 crfree(cred); 276 if (upperrootvp) 277 vrele(upperrootvp); 278 if (lowerrootvp) 279 vrele(lowerrootvp); 280 return (error); 281 } 282 283 /* 284 * VFS start. Nothing needed here - the start routine 285 * on the underlying filesystem(s) will have been called 286 * when that filesystem was mounted. 287 */ 288 /*ARGSUSED*/ 289 int 290 union_start(mp, flags, p) 291 struct mount *mp; 292 int flags; 293 struct proc *p; 294 { 295 296 return (0); 297 } 298 299 /* 300 * Free reference to union layer 301 */ 302 int 303 union_unmount(mp, mntflags, p) 304 struct mount *mp; 305 int mntflags; 306 struct proc *p; 307 { 308 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 309 struct vnode *um_rootvp; 310 int error; 311 int freeing; 312 313 #ifdef UNION_DIAGNOSTIC 314 printf("union_unmount(mp = %p)\n", mp); 315 #endif 316 317 if ((error = union_root(mp, &um_rootvp)) != 0) 318 return (error); 319 320 /* 321 * Keep flushing vnodes from the mount list. 322 * This is needed because of the un_pvp held 323 * reference to the parent vnode. 324 * If more vnodes have been freed on a given pass, 325 * the try again. The loop will iterate at most 326 * (d) times, where (d) is the maximum tree depth 327 * in the filesystem. 328 */ 329 for (freeing = 0; vflush(mp, um_rootvp, 0) != 0;) { 330 struct vnode *vp; 331 int n; 332 333 /* count #vnodes held on mount list */ 334 for (n = 0, vp = mp->mnt_vnodelist.lh_first; 335 vp != NULLVP; 336 vp = vp->v_mntvnodes.le_next) 337 n++; 338 339 /* if this is unchanged then stop */ 340 if (n == freeing) 341 break; 342 343 /* otherwise try once more time */ 344 freeing = n; 345 } 346 347 /* 348 * Ok, now that we've tried doing it gently, get out the hammer. 349 */ 350 351 if (mntflags & MNT_FORCE) 352 vflush(mp, um_rootvp, FORCECLOSE); 353 354 355 /* At this point the root vnode should have a single reference */ 356 if (um_rootvp->v_usecount > 1) { 357 vput(um_rootvp); 358 return (EBUSY); 359 } 360 361 #ifdef UNION_DIAGNOSTIC 362 vprint("union root", um_rootvp); 363 #endif 364 /* 365 * Discard references to upper and lower target vnodes. 366 */ 367 if (um->um_lowervp) 368 vrele(um->um_lowervp); 369 vrele(um->um_uppervp); 370 crfree(um->um_cred); 371 /* 372 * Release reference on underlying root vnode 373 */ 374 vput(um_rootvp); 375 /* 376 * And blow it away for future re-use 377 */ 378 vgone(um_rootvp); 379 /* 380 * Finally, throw away the union_mount structure 381 */ 382 free(mp->mnt_data, M_UFSMNT); /* XXX */ 383 mp->mnt_data = 0; 384 return (0); 385 } 386 387 int 388 union_root(mp, vpp) 389 struct mount *mp; 390 struct vnode **vpp; 391 { 392 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 393 int error; 394 int loselock; 395 396 /* 397 * Return locked reference to root. 398 */ 399 VREF(um->um_uppervp); 400 if ((um->um_op == UNMNT_BELOW) && 401 VOP_ISLOCKED(um->um_uppervp)) { 402 loselock = 1; 403 } else { 404 vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY); 405 loselock = 0; 406 } 407 if (um->um_lowervp) 408 VREF(um->um_lowervp); 409 error = union_allocvp(vpp, mp, 410 (struct vnode *) 0, 411 (struct vnode *) 0, 412 (struct componentname *) 0, 413 um->um_uppervp, 414 um->um_lowervp, 415 1); 416 417 if (error) { 418 if (!loselock) 419 VOP_UNLOCK(um->um_uppervp, 0); 420 vrele(um->um_uppervp); 421 if (um->um_lowervp) 422 vrele(um->um_lowervp); 423 } else { 424 if (loselock) 425 VTOUNION(*vpp)->un_flags &= ~UN_ULOCK; 426 } 427 428 return (error); 429 } 430 431 /*ARGSUSED*/ 432 int 433 union_quotactl(mp, cmd, uid, arg, p) 434 struct mount *mp; 435 int cmd; 436 uid_t uid; 437 caddr_t arg; 438 struct proc *p; 439 { 440 441 return (EOPNOTSUPP); 442 } 443 444 int 445 union_statfs(mp, sbp, p) 446 struct mount *mp; 447 struct statfs *sbp; 448 struct proc *p; 449 { 450 int error; 451 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 452 struct statfs mstat; 453 int lbsize; 454 455 #ifdef UNION_DIAGNOSTIC 456 printf("union_statfs(mp = %p, lvp = %p, uvp = %p)\n", mp, 457 um->um_lowervp, um->um_uppervp); 458 #endif 459 460 memset(&mstat, 0, sizeof(mstat)); 461 462 if (um->um_lowervp) { 463 error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, p); 464 if (error) 465 return (error); 466 } 467 468 /* now copy across the "interesting" information and fake the rest */ 469 lbsize = mstat.f_bsize; 470 sbp->f_blocks = mstat.f_blocks - mstat.f_bfree; 471 sbp->f_files = mstat.f_files - mstat.f_ffree; 472 473 error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, p); 474 if (error) 475 return (error); 476 477 sbp->f_type = 0; 478 sbp->f_flags = mstat.f_flags; 479 sbp->f_bsize = mstat.f_bsize; 480 sbp->f_iosize = mstat.f_iosize; 481 482 /* 483 * The "total" fields count total resources in all layers, 484 * the "free" fields count only those resources which are 485 * free in the upper layer (since only the upper layer 486 * is writable). 487 */ 488 489 if (mstat.f_bsize != lbsize) 490 sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize; 491 sbp->f_blocks += mstat.f_blocks; 492 sbp->f_bfree = mstat.f_bfree; 493 sbp->f_bavail = mstat.f_bavail; 494 sbp->f_files += mstat.f_files; 495 sbp->f_ffree = mstat.f_ffree; 496 497 copy_statfs_info(sbp, mp); 498 return (0); 499 } 500 501 /*ARGSUSED*/ 502 int 503 union_sync(mp, waitfor, cred, p) 504 struct mount *mp; 505 int waitfor; 506 struct ucred *cred; 507 struct proc *p; 508 { 509 510 /* 511 * XXX - Assumes no data cached at union layer. 512 */ 513 return (0); 514 } 515 516 /*ARGSUSED*/ 517 int 518 union_vget(mp, ino, vpp) 519 struct mount *mp; 520 ino_t ino; 521 struct vnode **vpp; 522 { 523 524 return (EOPNOTSUPP); 525 } 526 527 /*ARGSUSED*/ 528 int 529 union_fhtovp(mp, fidp, vpp) 530 struct mount *mp; 531 struct fid *fidp; 532 struct vnode **vpp; 533 { 534 535 return (EOPNOTSUPP); 536 } 537 538 /*ARGSUSED*/ 539 int 540 union_checkexp(mp, nam, exflagsp, credanonp) 541 struct mount *mp; 542 struct mbuf *nam; 543 int *exflagsp; 544 struct ucred **credanonp; 545 { 546 547 return (EOPNOTSUPP); 548 } 549 550 /*ARGSUSED*/ 551 int 552 union_vptofh(vp, fhp) 553 struct vnode *vp; 554 struct fid *fhp; 555 { 556 557 return (EOPNOTSUPP); 558 } 559 560 int 561 union_sysctl(name, namelen, oldp, oldlenp, newp, newlen, p) 562 int *name; 563 u_int namelen; 564 void *oldp; 565 size_t *oldlenp; 566 void *newp; 567 size_t newlen; 568 struct proc *p; 569 { 570 return (EOPNOTSUPP); 571 } 572 573 extern const struct vnodeopv_desc union_vnodeop_opv_desc; 574 575 const struct vnodeopv_desc * const union_vnodeopv_descs[] = { 576 &union_vnodeop_opv_desc, 577 NULL, 578 }; 579 580 struct vfsops union_vfsops = { 581 MOUNT_UNION, 582 union_mount, 583 union_start, 584 union_unmount, 585 union_root, 586 union_quotactl, 587 union_statfs, 588 union_sync, 589 union_vget, 590 union_fhtovp, 591 union_vptofh, 592 union_init, 593 NULL, /* vfs_reinit */ 594 union_done, 595 union_sysctl, 596 NULL, /* vfs_mountroot */ 597 union_checkexp, 598 union_vnodeopv_descs, 599 }; 600