1 /* $NetBSD: fss.c,v 1.64 2009/10/13 12:37:19 hannken Exp $ */ 2 3 /*- 4 * Copyright (c) 2003 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Juergen Hannken-Illjes. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * File system snapshot disk driver. 34 * 35 * Block/character interface to the snapshot of a mounted file system. 36 */ 37 38 #include <sys/cdefs.h> 39 __KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.64 2009/10/13 12:37:19 hannken Exp $"); 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/namei.h> 44 #include <sys/proc.h> 45 #include <sys/errno.h> 46 #include <sys/malloc.h> 47 #include <sys/buf.h> 48 #include <sys/ioctl.h> 49 #include <sys/disklabel.h> 50 #include <sys/device.h> 51 #include <sys/disk.h> 52 #include <sys/stat.h> 53 #include <sys/mount.h> 54 #include <sys/vnode.h> 55 #include <sys/file.h> 56 #include <sys/uio.h> 57 #include <sys/conf.h> 58 #include <sys/kthread.h> 59 #include <sys/fstrans.h> 60 #include <sys/simplelock.h> 61 62 #include <miscfs/specfs/specdev.h> 63 64 #include <dev/fssvar.h> 65 66 #include <uvm/uvm.h> 67 68 void fssattach(int); 69 70 dev_type_open(fss_open); 71 dev_type_close(fss_close); 72 dev_type_read(fss_read); 73 dev_type_write(fss_write); 74 dev_type_ioctl(fss_ioctl); 75 dev_type_strategy(fss_strategy); 76 dev_type_dump(fss_dump); 77 dev_type_size(fss_size); 78 79 static void fss_unmount_hook(struct mount *); 80 static int fss_copy_on_write(void *, struct buf *, bool); 81 static inline void fss_error(struct fss_softc *, const char *); 82 static int fss_create_files(struct fss_softc *, struct fss_set *, 83 off_t *, struct lwp *); 84 static int fss_create_snapshot(struct fss_softc *, struct fss_set *, 85 struct lwp *); 86 static int fss_delete_snapshot(struct fss_softc *, struct lwp *); 87 static int fss_softc_alloc(struct fss_softc *); 88 static void fss_softc_free(struct fss_softc *); 89 static int fss_read_cluster(struct fss_softc *, u_int32_t); 90 static void fss_bs_thread(void *); 91 static int fss_bs_io(struct fss_softc *, fss_io_type, 92 u_int32_t, off_t, int, void *); 93 static u_int32_t *fss_bs_indir(struct fss_softc *, u_int32_t); 94 95 static kmutex_t fss_device_lock; /* Protect all units. */ 96 static int fss_num_attached = 0; /* Number of attached devices. */ 97 static struct vfs_hooks fss_vfs_hooks = { 98 .vh_unmount = fss_unmount_hook 99 }; 100 101 const struct bdevsw fss_bdevsw = { 102 fss_open, fss_close, fss_strategy, fss_ioctl, 103 fss_dump, fss_size, D_DISK | D_MPSAFE 104 }; 105 106 const struct cdevsw fss_cdevsw = { 107 fss_open, fss_close, fss_read, fss_write, fss_ioctl, 108 nostop, notty, nopoll, nommap, nokqfilter, D_DISK | D_MPSAFE 109 }; 110 111 static int fss_match(device_t, cfdata_t, void *); 112 static void fss_attach(device_t, device_t, void *); 113 static int fss_detach(device_t, int); 114 115 CFATTACH_DECL_NEW(fss, sizeof(struct fss_softc), 116 fss_match, fss_attach, fss_detach, NULL); 117 extern struct cfdriver fss_cd; 118 119 void 120 fssattach(int num) 121 { 122 123 mutex_init(&fss_device_lock, MUTEX_DEFAULT, IPL_NONE); 124 if (config_cfattach_attach(fss_cd.cd_name, &fss_ca)) 125 aprint_error("%s: unable to register\n", fss_cd.cd_name); 126 } 127 128 static int 129 fss_match(device_t self, cfdata_t cfdata, void *aux) 130 { 131 return 1; 132 } 133 134 static void 135 fss_attach(device_t parent, device_t self, void *aux) 136 { 137 struct fss_softc *sc = device_private(self); 138 139 sc->sc_dev = self; 140 sc->sc_bdev = NODEV; 141 mutex_init(&sc->sc_slock, MUTEX_DEFAULT, IPL_NONE); 142 mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE); 143 cv_init(&sc->sc_work_cv, "fssbs"); 144 cv_init(&sc->sc_cache_cv, "cowwait"); 145 bufq_alloc(&sc->sc_bufq, "fcfs", 0); 146 sc->sc_dkdev = malloc(sizeof(*sc->sc_dkdev), M_DEVBUF, M_WAITOK); 147 sc->sc_dkdev->dk_info = NULL; 148 disk_init(sc->sc_dkdev, device_xname(self), NULL); 149 if (!pmf_device_register(self, NULL, NULL)) 150 aprint_error_dev(self, "couldn't establish power handler\n"); 151 152 if (fss_num_attached++ == 0) 153 vfs_hooks_attach(&fss_vfs_hooks); 154 } 155 156 static int 157 fss_detach(device_t self, int flags) 158 { 159 struct fss_softc *sc = device_private(self); 160 161 if (sc->sc_flags & FSS_ACTIVE) 162 return EBUSY; 163 164 if (--fss_num_attached == 0) 165 vfs_hooks_detach(&fss_vfs_hooks); 166 167 pmf_device_deregister(self); 168 mutex_destroy(&sc->sc_slock); 169 mutex_destroy(&sc->sc_lock); 170 cv_destroy(&sc->sc_work_cv); 171 cv_destroy(&sc->sc_cache_cv); 172 bufq_drain(sc->sc_bufq); 173 bufq_free(sc->sc_bufq); 174 disk_destroy(sc->sc_dkdev); 175 free(sc->sc_dkdev, M_DEVBUF); 176 177 return 0; 178 } 179 180 int 181 fss_open(dev_t dev, int flags, int mode, struct lwp *l) 182 { 183 int mflag; 184 cfdata_t cf; 185 struct fss_softc *sc; 186 187 mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN); 188 189 mutex_enter(&fss_device_lock); 190 191 sc = device_lookup_private(&fss_cd, minor(dev)); 192 if (sc == NULL) { 193 cf = malloc(sizeof(*cf), M_DEVBUF, M_WAITOK); 194 cf->cf_name = fss_cd.cd_name; 195 cf->cf_atname = fss_cd.cd_name; 196 cf->cf_unit = minor(dev); 197 cf->cf_fstate = FSTATE_STAR; 198 sc = device_private(config_attach_pseudo(cf)); 199 if (sc == NULL) 200 return ENOMEM; 201 } 202 203 mutex_enter(&sc->sc_slock); 204 205 sc->sc_flags |= mflag; 206 207 mutex_exit(&sc->sc_slock); 208 mutex_exit(&fss_device_lock); 209 210 return 0; 211 } 212 213 int 214 fss_close(dev_t dev, int flags, int mode, struct lwp *l) 215 { 216 int mflag, error; 217 cfdata_t cf; 218 struct fss_softc *sc = device_lookup_private(&fss_cd, minor(dev)); 219 220 mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN); 221 error = 0; 222 223 restart: 224 mutex_enter(&sc->sc_slock); 225 if ((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) != mflag) { 226 sc->sc_flags &= ~mflag; 227 mutex_exit(&sc->sc_slock); 228 return 0; 229 } 230 if ((sc->sc_flags & FSS_ACTIVE) != 0 && 231 (sc->sc_uflags & FSS_UNCONFIG_ON_CLOSE) != 0) { 232 sc->sc_uflags &= ~FSS_UNCONFIG_ON_CLOSE; 233 mutex_exit(&sc->sc_slock); 234 error = fss_ioctl(dev, FSSIOCCLR, NULL, FWRITE, l); 235 goto restart; 236 } 237 if ((sc->sc_flags & FSS_ACTIVE) != 0) { 238 mutex_exit(&sc->sc_slock); 239 return error; 240 } 241 if (! mutex_tryenter(&fss_device_lock)) { 242 mutex_exit(&sc->sc_slock); 243 goto restart; 244 } 245 246 KASSERT((sc->sc_flags & FSS_ACTIVE) == 0); 247 KASSERT((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) == mflag); 248 mutex_exit(&sc->sc_slock); 249 cf = device_cfdata(sc->sc_dev); 250 error = config_detach(sc->sc_dev, DETACH_QUIET); 251 if (! error) 252 free(cf, M_DEVBUF); 253 mutex_exit(&fss_device_lock); 254 255 return error; 256 } 257 258 void 259 fss_strategy(struct buf *bp) 260 { 261 const bool write = ((bp->b_flags & B_READ) != B_READ); 262 struct fss_softc *sc = device_lookup_private(&fss_cd, minor(bp->b_dev)); 263 264 mutex_enter(&sc->sc_slock); 265 266 if (write || !FSS_ISVALID(sc)) { 267 268 mutex_exit(&sc->sc_slock); 269 270 bp->b_error = (write ? EROFS : ENXIO); 271 bp->b_resid = bp->b_bcount; 272 biodone(bp); 273 return; 274 } 275 276 bp->b_rawblkno = bp->b_blkno; 277 bufq_put(sc->sc_bufq, bp); 278 cv_signal(&sc->sc_work_cv); 279 280 mutex_exit(&sc->sc_slock); 281 } 282 283 int 284 fss_read(dev_t dev, struct uio *uio, int flags) 285 { 286 return physio(fss_strategy, NULL, dev, B_READ, minphys, uio); 287 } 288 289 int 290 fss_write(dev_t dev, struct uio *uio, int flags) 291 { 292 return physio(fss_strategy, NULL, dev, B_WRITE, minphys, uio); 293 } 294 295 int 296 fss_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l) 297 { 298 int error; 299 struct fss_softc *sc = device_lookup_private(&fss_cd, minor(dev)); 300 struct fss_set *fss = (struct fss_set *)data; 301 struct fss_get *fsg = (struct fss_get *)data; 302 303 switch (cmd) { 304 case FSSIOCSET: 305 mutex_enter(&sc->sc_lock); 306 if ((flag & FWRITE) == 0) 307 error = EPERM; 308 else if ((sc->sc_flags & FSS_ACTIVE) != 0) 309 error = EBUSY; 310 else 311 error = fss_create_snapshot(sc, fss, l); 312 mutex_exit(&sc->sc_lock); 313 break; 314 315 case FSSIOCCLR: 316 mutex_enter(&sc->sc_lock); 317 if ((flag & FWRITE) == 0) 318 error = EPERM; 319 else if ((sc->sc_flags & FSS_ACTIVE) == 0) 320 error = ENXIO; 321 else 322 error = fss_delete_snapshot(sc, l); 323 mutex_exit(&sc->sc_lock); 324 break; 325 326 case FSSIOCGET: 327 mutex_enter(&sc->sc_lock); 328 switch (sc->sc_flags & (FSS_PERSISTENT | FSS_ACTIVE)) { 329 case FSS_ACTIVE: 330 memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN); 331 fsg->fsg_csize = FSS_CLSIZE(sc); 332 fsg->fsg_time = sc->sc_time; 333 fsg->fsg_mount_size = sc->sc_clcount; 334 fsg->fsg_bs_size = sc->sc_clnext; 335 error = 0; 336 break; 337 case FSS_PERSISTENT | FSS_ACTIVE: 338 memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN); 339 fsg->fsg_csize = 0; 340 fsg->fsg_time = sc->sc_time; 341 fsg->fsg_mount_size = 0; 342 fsg->fsg_bs_size = 0; 343 error = 0; 344 break; 345 default: 346 error = ENXIO; 347 break; 348 } 349 mutex_exit(&sc->sc_lock); 350 break; 351 352 case FSSIOFSET: 353 mutex_enter(&sc->sc_slock); 354 sc->sc_uflags = *(int *)data; 355 mutex_exit(&sc->sc_slock); 356 error = 0; 357 break; 358 359 case FSSIOFGET: 360 mutex_enter(&sc->sc_slock); 361 *(int *)data = sc->sc_uflags; 362 mutex_exit(&sc->sc_slock); 363 error = 0; 364 break; 365 366 default: 367 error = EINVAL; 368 break; 369 } 370 371 return error; 372 } 373 374 int 375 fss_size(dev_t dev) 376 { 377 return -1; 378 } 379 380 int 381 fss_dump(dev_t dev, daddr_t blkno, void *va, 382 size_t size) 383 { 384 return EROFS; 385 } 386 387 /* 388 * An error occurred reading or writing the snapshot or backing store. 389 * If it is the first error log to console. 390 * The caller holds the mutex. 391 */ 392 static inline void 393 fss_error(struct fss_softc *sc, const char *msg) 394 { 395 396 if ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE) 397 aprint_error_dev(sc->sc_dev, "snapshot invalid: %s\n", msg); 398 if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE) 399 sc->sc_flags |= FSS_ERROR; 400 } 401 402 /* 403 * Allocate the variable sized parts of the softc and 404 * fork the kernel thread. 405 * 406 * The fields sc_clcount, sc_clshift, sc_cache_size and sc_indir_size 407 * must be initialized. 408 */ 409 static int 410 fss_softc_alloc(struct fss_softc *sc) 411 { 412 int i, error; 413 414 if ((sc->sc_flags & FSS_PERSISTENT) == 0) { 415 sc->sc_copied = 416 kmem_zalloc(howmany(sc->sc_clcount, NBBY), KM_SLEEP); 417 if (sc->sc_copied == NULL) 418 return(ENOMEM); 419 420 sc->sc_cache = kmem_alloc(sc->sc_cache_size * 421 sizeof(struct fss_cache), KM_SLEEP); 422 if (sc->sc_cache == NULL) 423 return(ENOMEM); 424 425 for (i = 0; i < sc->sc_cache_size; i++) { 426 sc->sc_cache[i].fc_type = FSS_CACHE_FREE; 427 sc->sc_cache[i].fc_data = 428 kmem_alloc(FSS_CLSIZE(sc), KM_SLEEP); 429 if (sc->sc_cache[i].fc_data == NULL) 430 return(ENOMEM); 431 cv_init(&sc->sc_cache[i].fc_state_cv, "cowwait1"); 432 } 433 434 sc->sc_indir_valid = 435 kmem_zalloc(howmany(sc->sc_indir_size, NBBY), KM_SLEEP); 436 if (sc->sc_indir_valid == NULL) 437 return(ENOMEM); 438 439 sc->sc_indir_data = kmem_zalloc(FSS_CLSIZE(sc), KM_SLEEP); 440 if (sc->sc_indir_data == NULL) 441 return(ENOMEM); 442 } else { 443 sc->sc_copied = NULL; 444 sc->sc_cache = NULL; 445 sc->sc_indir_valid = NULL; 446 sc->sc_indir_data = NULL; 447 } 448 449 sc->sc_flags |= FSS_BS_THREAD; 450 if ((error = kthread_create(PRI_BIO, 0, NULL, fss_bs_thread, sc, 451 &sc->sc_bs_lwp, device_xname(sc->sc_dev))) != 0) { 452 sc->sc_flags &= ~FSS_BS_THREAD; 453 return error; 454 } 455 456 disk_attach(sc->sc_dkdev); 457 458 return 0; 459 } 460 461 /* 462 * Free the variable sized parts of the softc. 463 */ 464 static void 465 fss_softc_free(struct fss_softc *sc) 466 { 467 int i; 468 469 if ((sc->sc_flags & FSS_BS_THREAD) != 0) { 470 mutex_enter(&sc->sc_slock); 471 sc->sc_flags &= ~FSS_BS_THREAD; 472 cv_signal(&sc->sc_work_cv); 473 while (sc->sc_bs_lwp != NULL) 474 kpause("fssdetach", false, 1, &sc->sc_slock); 475 mutex_exit(&sc->sc_slock); 476 } 477 478 disk_detach(sc->sc_dkdev); 479 480 if (sc->sc_copied != NULL) 481 kmem_free(sc->sc_copied, howmany(sc->sc_clcount, NBBY)); 482 sc->sc_copied = NULL; 483 484 if (sc->sc_cache != NULL) { 485 for (i = 0; i < sc->sc_cache_size; i++) 486 if (sc->sc_cache[i].fc_data != NULL) { 487 cv_destroy(&sc->sc_cache[i].fc_state_cv); 488 kmem_free(sc->sc_cache[i].fc_data, 489 FSS_CLSIZE(sc)); 490 } 491 kmem_free(sc->sc_cache, 492 sc->sc_cache_size*sizeof(struct fss_cache)); 493 } 494 sc->sc_cache = NULL; 495 496 if (sc->sc_indir_valid != NULL) 497 kmem_free(sc->sc_indir_valid, howmany(sc->sc_indir_size, NBBY)); 498 sc->sc_indir_valid = NULL; 499 500 if (sc->sc_indir_data != NULL) 501 kmem_free(sc->sc_indir_data, FSS_CLSIZE(sc)); 502 sc->sc_indir_data = NULL; 503 } 504 505 /* 506 * Set all active snapshots on this file system into ERROR state. 507 */ 508 static void 509 fss_unmount_hook(struct mount *mp) 510 { 511 int i; 512 struct fss_softc *sc; 513 514 mutex_enter(&fss_device_lock); 515 for (i = 0; i < fss_cd.cd_ndevs; i++) { 516 if ((sc = device_lookup_private(&fss_cd, i)) == NULL) 517 continue; 518 mutex_enter(&sc->sc_slock); 519 if ((sc->sc_flags & FSS_ACTIVE) != 0 && 520 sc->sc_mount == mp) 521 fss_error(sc, "forced unmount"); 522 mutex_exit(&sc->sc_slock); 523 } 524 mutex_exit(&fss_device_lock); 525 } 526 527 /* 528 * A buffer is written to the snapshotted block device. Copy to 529 * backing store if needed. 530 */ 531 static int 532 fss_copy_on_write(void *v, struct buf *bp, bool data_valid) 533 { 534 int error; 535 u_int32_t cl, ch, c; 536 struct fss_softc *sc = v; 537 538 mutex_enter(&sc->sc_slock); 539 if (!FSS_ISVALID(sc)) { 540 mutex_exit(&sc->sc_slock); 541 return 0; 542 } 543 544 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); 545 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); 546 error = 0; 547 if (curlwp == uvm.pagedaemon_lwp) { 548 for (c = cl; c <= ch; c++) 549 if (isclr(sc->sc_copied, c)) { 550 error = ENOMEM; 551 break; 552 } 553 } 554 mutex_exit(&sc->sc_slock); 555 556 if (error == 0) 557 for (c = cl; c <= ch; c++) { 558 error = fss_read_cluster(sc, c); 559 if (error) 560 break; 561 } 562 563 return error; 564 } 565 566 /* 567 * Lookup and open needed files. 568 * 569 * For file system internal snapshot initializes sc_mntname, sc_mount, 570 * sc_bs_vp and sc_time. 571 * 572 * Otherwise returns dev and size of the underlying block device. 573 * Initializes sc_mntname, sc_mount, sc_bdev, sc_bs_vp and sc_mount 574 */ 575 static int 576 fss_create_files(struct fss_softc *sc, struct fss_set *fss, 577 off_t *bsize, struct lwp *l) 578 { 579 int error, bits, fsbsize; 580 struct timespec ts; 581 struct partinfo dpart; 582 struct vattr va; 583 /* nd -> nd2 to reduce mistakes while updating only some namei calls */ 584 struct nameidata nd2; 585 struct vnode *vp; 586 587 /* 588 * Get the mounted file system. 589 */ 590 591 error = namei_simple_user(fss->fss_mount, 592 NSM_FOLLOW_NOEMULROOT, &vp); 593 if (error != 0) 594 return error; 595 596 if ((vp->v_vflag & VV_ROOT) != VV_ROOT) { 597 vrele(vp); 598 return EINVAL; 599 } 600 601 sc->sc_mount = vp->v_mount; 602 memcpy(sc->sc_mntname, sc->sc_mount->mnt_stat.f_mntonname, MNAMELEN); 603 604 vrele(vp); 605 606 /* 607 * Check for file system internal snapshot. 608 */ 609 610 error = namei_simple_user(fss->fss_bstore, 611 NSM_FOLLOW_NOEMULROOT, &vp); 612 if (error != 0) 613 return error; 614 error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 615 if (error != 0) { 616 vrele(vp); 617 return error; 618 } 619 620 if (vp->v_type == VREG && vp->v_mount == sc->sc_mount) { 621 sc->sc_flags |= FSS_PERSISTENT; 622 sc->sc_bs_vp = vp; 623 624 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; 625 bits = sizeof(sc->sc_bs_bshift)*NBBY; 626 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < bits; 627 sc->sc_bs_bshift++) 628 if (FSS_FSBSIZE(sc) == fsbsize) 629 break; 630 if (sc->sc_bs_bshift >= bits) { 631 VOP_UNLOCK(sc->sc_bs_vp, 0); 632 return EINVAL; 633 } 634 635 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 636 sc->sc_clshift = 0; 637 638 error = VFS_SNAPSHOT(sc->sc_mount, sc->sc_bs_vp, &ts); 639 TIMESPEC_TO_TIMEVAL(&sc->sc_time, &ts); 640 641 VOP_UNLOCK(sc->sc_bs_vp, 0); 642 643 return error; 644 } 645 vput(vp); 646 647 /* 648 * Get the block device it is mounted on. 649 */ 650 651 error = namei_simple_kernel(sc->sc_mount->mnt_stat.f_mntfromname, 652 NSM_FOLLOW_NOEMULROOT, &vp); 653 if (error != 0) 654 return error; 655 656 if (vp->v_type != VBLK) { 657 vrele(vp); 658 return EINVAL; 659 } 660 661 sc->sc_bdev = vp->v_rdev; 662 vrele(vp); 663 664 /* 665 * Get the block device size. 666 */ 667 668 error = bdev_ioctl(sc->sc_bdev, DIOCGPART, &dpart, FREAD, l); 669 if (error) 670 return error; 671 672 *bsize = (off_t)dpart.disklab->d_secsize*dpart.part->p_size; 673 674 /* 675 * Get the backing store 676 */ 677 678 NDINIT(&nd2, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore); 679 if ((error = vn_open(&nd2, FREAD|FWRITE, 0)) != 0) 680 return error; 681 VOP_UNLOCK(nd2.ni_vp, 0); 682 683 sc->sc_bs_vp = nd2.ni_vp; 684 685 if (nd2.ni_vp->v_type != VREG && nd2.ni_vp->v_type != VCHR) 686 return EINVAL; 687 688 if (sc->sc_bs_vp->v_type == VREG) { 689 error = VOP_GETATTR(sc->sc_bs_vp, &va, l->l_cred); 690 if (error != 0) 691 return error; 692 sc->sc_bs_size = va.va_size; 693 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; 694 if (fsbsize & (fsbsize-1)) /* No power of two */ 695 return EINVAL; 696 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < 32; 697 sc->sc_bs_bshift++) 698 if (FSS_FSBSIZE(sc) == fsbsize) 699 break; 700 if (sc->sc_bs_bshift >= 32) 701 return EINVAL; 702 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 703 } else { 704 sc->sc_bs_bshift = DEV_BSHIFT; 705 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 706 } 707 708 /* 709 * As all IO to from/to the backing store goes through 710 * VOP_STRATEGY() clean the buffer cache to prevent 711 * cache incoherencies. 712 */ 713 if ((error = vinvalbuf(sc->sc_bs_vp, V_SAVE, l->l_cred, l, 0, 0)) != 0) 714 return error; 715 716 return 0; 717 } 718 719 /* 720 * Create a snapshot. 721 */ 722 static int 723 fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct lwp *l) 724 { 725 int len, error; 726 u_int32_t csize; 727 off_t bsize; 728 729 bsize = 0; /* XXX gcc */ 730 731 /* 732 * Open needed files. 733 */ 734 if ((error = fss_create_files(sc, fss, &bsize, l)) != 0) 735 goto bad; 736 737 if (sc->sc_flags & FSS_PERSISTENT) { 738 fss_softc_alloc(sc); 739 sc->sc_flags |= FSS_ACTIVE; 740 return 0; 741 } 742 743 /* 744 * Set cluster size. Must be a power of two and 745 * a multiple of backing store block size. 746 */ 747 if (fss->fss_csize <= 0) 748 csize = MAXPHYS; 749 else 750 csize = fss->fss_csize; 751 if (bsize/csize > FSS_CLUSTER_MAX) 752 csize = bsize/FSS_CLUSTER_MAX+1; 753 754 for (sc->sc_clshift = sc->sc_bs_bshift; sc->sc_clshift < 32; 755 sc->sc_clshift++) 756 if (FSS_CLSIZE(sc) >= csize) 757 break; 758 if (sc->sc_clshift >= 32) { 759 error = EINVAL; 760 goto bad; 761 } 762 sc->sc_clmask = FSS_CLSIZE(sc)-1; 763 764 /* 765 * Set number of cache slots. 766 */ 767 if (FSS_CLSIZE(sc) <= 8192) 768 sc->sc_cache_size = 32; 769 else if (FSS_CLSIZE(sc) <= 65536) 770 sc->sc_cache_size = 8; 771 else 772 sc->sc_cache_size = 4; 773 774 /* 775 * Set number of clusters and size of last cluster. 776 */ 777 sc->sc_clcount = FSS_BTOCL(sc, bsize-1)+1; 778 sc->sc_clresid = FSS_CLOFF(sc, bsize-1)+1; 779 780 /* 781 * Set size of indirect table. 782 */ 783 len = sc->sc_clcount*sizeof(u_int32_t); 784 sc->sc_indir_size = FSS_BTOCL(sc, len)+1; 785 sc->sc_clnext = sc->sc_indir_size; 786 sc->sc_indir_cur = 0; 787 788 if ((error = fss_softc_alloc(sc)) != 0) 789 goto bad; 790 791 /* 792 * Activate the snapshot. 793 */ 794 795 if ((error = vfs_suspend(sc->sc_mount, 0)) != 0) 796 goto bad; 797 798 microtime(&sc->sc_time); 799 800 if (error == 0) 801 error = fscow_establish(sc->sc_mount, 802 fss_copy_on_write, sc); 803 if (error == 0) 804 sc->sc_flags |= FSS_ACTIVE; 805 806 vfs_resume(sc->sc_mount); 807 808 if (error != 0) 809 goto bad; 810 811 aprint_debug_dev(sc->sc_dev, "%s snapshot active\n", sc->sc_mntname); 812 aprint_debug_dev(sc->sc_dev, 813 "%u clusters of %u, %u cache slots, %u indir clusters\n", 814 sc->sc_clcount, FSS_CLSIZE(sc), 815 sc->sc_cache_size, sc->sc_indir_size); 816 817 return 0; 818 819 bad: 820 fss_softc_free(sc); 821 if (sc->sc_bs_vp != NULL) { 822 if (sc->sc_flags & FSS_PERSISTENT) 823 vn_close(sc->sc_bs_vp, FREAD, l->l_cred); 824 else 825 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred); 826 } 827 sc->sc_bs_vp = NULL; 828 829 return error; 830 } 831 832 /* 833 * Delete a snapshot. 834 */ 835 static int 836 fss_delete_snapshot(struct fss_softc *sc, struct lwp *l) 837 { 838 839 if ((sc->sc_flags & FSS_PERSISTENT) == 0) 840 fscow_disestablish(sc->sc_mount, fss_copy_on_write, sc); 841 842 mutex_enter(&sc->sc_slock); 843 sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR); 844 sc->sc_mount = NULL; 845 sc->sc_bdev = NODEV; 846 mutex_exit(&sc->sc_slock); 847 848 fss_softc_free(sc); 849 if (sc->sc_flags & FSS_PERSISTENT) 850 vn_close(sc->sc_bs_vp, FREAD, l->l_cred); 851 else 852 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred); 853 sc->sc_bs_vp = NULL; 854 sc->sc_flags &= ~FSS_PERSISTENT; 855 856 return 0; 857 } 858 859 /* 860 * Read a cluster from the snapshotted block device to the cache. 861 */ 862 static int 863 fss_read_cluster(struct fss_softc *sc, u_int32_t cl) 864 { 865 int error, todo, offset, len; 866 daddr_t dblk; 867 struct buf *bp, *mbp; 868 struct fss_cache *scp, *scl; 869 870 /* 871 * Get a free cache slot. 872 */ 873 scl = sc->sc_cache+sc->sc_cache_size; 874 875 mutex_enter(&sc->sc_slock); 876 877 restart: 878 if (isset(sc->sc_copied, cl) || !FSS_ISVALID(sc)) { 879 mutex_exit(&sc->sc_slock); 880 return 0; 881 } 882 883 for (scp = sc->sc_cache; scp < scl; scp++) 884 if (scp->fc_cluster == cl) { 885 if (scp->fc_type == FSS_CACHE_VALID) { 886 mutex_exit(&sc->sc_slock); 887 return 0; 888 } else if (scp->fc_type == FSS_CACHE_BUSY) { 889 cv_wait(&scp->fc_state_cv, &sc->sc_slock); 890 goto restart; 891 } 892 } 893 894 for (scp = sc->sc_cache; scp < scl; scp++) 895 if (scp->fc_type == FSS_CACHE_FREE) { 896 scp->fc_type = FSS_CACHE_BUSY; 897 scp->fc_cluster = cl; 898 break; 899 } 900 if (scp >= scl) { 901 cv_wait(&sc->sc_cache_cv, &sc->sc_slock); 902 goto restart; 903 } 904 905 mutex_exit(&sc->sc_slock); 906 907 /* 908 * Start the read. 909 */ 910 dblk = btodb(FSS_CLTOB(sc, cl)); 911 if (cl == sc->sc_clcount-1) { 912 todo = sc->sc_clresid; 913 memset((char *)scp->fc_data + todo, 0, FSS_CLSIZE(sc) - todo); 914 } else 915 todo = FSS_CLSIZE(sc); 916 offset = 0; 917 mbp = getiobuf(NULL, true); 918 mbp->b_bufsize = todo; 919 mbp->b_data = scp->fc_data; 920 mbp->b_resid = mbp->b_bcount = todo; 921 mbp->b_flags = B_READ; 922 mbp->b_cflags = BC_BUSY; 923 mbp->b_dev = sc->sc_bdev; 924 while (todo > 0) { 925 len = todo; 926 if (len > MAXPHYS) 927 len = MAXPHYS; 928 if (btodb(FSS_CLTOB(sc, cl)) == dblk && len == todo) 929 bp = mbp; 930 else { 931 bp = getiobuf(NULL, true); 932 nestiobuf_setup(mbp, bp, offset, len); 933 } 934 bp->b_lblkno = 0; 935 bp->b_blkno = dblk; 936 bdev_strategy(bp); 937 dblk += btodb(len); 938 offset += len; 939 todo -= len; 940 } 941 error = biowait(mbp); 942 putiobuf(mbp); 943 944 mutex_enter(&sc->sc_slock); 945 scp->fc_type = (error ? FSS_CACHE_FREE : FSS_CACHE_VALID); 946 cv_broadcast(&scp->fc_state_cv); 947 if (error == 0) { 948 setbit(sc->sc_copied, scp->fc_cluster); 949 cv_signal(&sc->sc_work_cv); 950 } 951 mutex_exit(&sc->sc_slock); 952 953 return error; 954 } 955 956 /* 957 * Read/write clusters from/to backing store. 958 * For persistent snapshots must be called with cl == 0. off is the 959 * offset into the snapshot. 960 */ 961 static int 962 fss_bs_io(struct fss_softc *sc, fss_io_type rw, 963 u_int32_t cl, off_t off, int len, void *data) 964 { 965 int error; 966 967 off += FSS_CLTOB(sc, cl); 968 969 vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY); 970 971 error = vn_rdwr((rw == FSS_READ ? UIO_READ : UIO_WRITE), sc->sc_bs_vp, 972 data, len, off, UIO_SYSSPACE, IO_UNIT|IO_NODELOCKED, 973 sc->sc_bs_lwp->l_cred, NULL, NULL); 974 if (error == 0) { 975 mutex_enter(&sc->sc_bs_vp->v_interlock); 976 error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(off), 977 round_page(off+len), PGO_CLEANIT|PGO_SYNCIO|PGO_FREE); 978 } 979 980 VOP_UNLOCK(sc->sc_bs_vp, 0); 981 982 return error; 983 } 984 985 /* 986 * Get a pointer to the indirect slot for this cluster. 987 */ 988 static u_int32_t * 989 fss_bs_indir(struct fss_softc *sc, u_int32_t cl) 990 { 991 u_int32_t icl; 992 int ioff; 993 994 icl = cl/(FSS_CLSIZE(sc)/sizeof(u_int32_t)); 995 ioff = cl%(FSS_CLSIZE(sc)/sizeof(u_int32_t)); 996 997 if (sc->sc_indir_cur == icl) 998 return &sc->sc_indir_data[ioff]; 999 1000 if (sc->sc_indir_dirty) { 1001 if (fss_bs_io(sc, FSS_WRITE, sc->sc_indir_cur, 0, 1002 FSS_CLSIZE(sc), (void *)sc->sc_indir_data) != 0) 1003 return NULL; 1004 setbit(sc->sc_indir_valid, sc->sc_indir_cur); 1005 } 1006 1007 sc->sc_indir_dirty = 0; 1008 sc->sc_indir_cur = icl; 1009 1010 if (isset(sc->sc_indir_valid, sc->sc_indir_cur)) { 1011 if (fss_bs_io(sc, FSS_READ, sc->sc_indir_cur, 0, 1012 FSS_CLSIZE(sc), (void *)sc->sc_indir_data) != 0) 1013 return NULL; 1014 } else 1015 memset(sc->sc_indir_data, 0, FSS_CLSIZE(sc)); 1016 1017 return &sc->sc_indir_data[ioff]; 1018 } 1019 1020 /* 1021 * The kernel thread (one for every active snapshot). 1022 * 1023 * After wakeup it cleans the cache and runs the I/O requests. 1024 */ 1025 static void 1026 fss_bs_thread(void *arg) 1027 { 1028 bool thread_idle, is_valid; 1029 int error, i, todo, len, crotor, is_read; 1030 long off; 1031 char *addr; 1032 u_int32_t c, cl, ch, *indirp; 1033 struct buf *bp, *nbp; 1034 struct fss_softc *sc; 1035 struct fss_cache *scp, *scl; 1036 1037 sc = arg; 1038 scl = sc->sc_cache+sc->sc_cache_size; 1039 crotor = 0; 1040 thread_idle = false; 1041 1042 mutex_enter(&sc->sc_slock); 1043 1044 for (;;) { 1045 if (thread_idle) 1046 cv_wait(&sc->sc_work_cv, &sc->sc_slock); 1047 thread_idle = true; 1048 if ((sc->sc_flags & FSS_BS_THREAD) == 0) { 1049 sc->sc_bs_lwp = NULL; 1050 mutex_exit(&sc->sc_slock); 1051 kthread_exit(0); 1052 } 1053 1054 /* 1055 * Process I/O requests (persistent) 1056 */ 1057 1058 if (sc->sc_flags & FSS_PERSISTENT) { 1059 if ((bp = bufq_get(sc->sc_bufq)) == NULL) 1060 continue; 1061 is_valid = FSS_ISVALID(sc); 1062 is_read = (bp->b_flags & B_READ); 1063 thread_idle = false; 1064 mutex_exit(&sc->sc_slock); 1065 1066 if (is_valid) { 1067 disk_busy(sc->sc_dkdev); 1068 error = fss_bs_io(sc, FSS_READ, 0, 1069 dbtob(bp->b_blkno), bp->b_bcount, 1070 bp->b_data); 1071 disk_unbusy(sc->sc_dkdev, 1072 (error ? 0 : bp->b_bcount), is_read); 1073 } else 1074 error = ENXIO; 1075 1076 bp->b_error = error; 1077 bp->b_resid = (error ? bp->b_bcount : 0); 1078 biodone(bp); 1079 1080 mutex_enter(&sc->sc_slock); 1081 continue; 1082 } 1083 1084 /* 1085 * Clean the cache 1086 */ 1087 for (i = 0; i < sc->sc_cache_size; i++) { 1088 crotor = (crotor + 1) % sc->sc_cache_size; 1089 scp = sc->sc_cache + crotor; 1090 if (scp->fc_type != FSS_CACHE_VALID) 1091 continue; 1092 mutex_exit(&sc->sc_slock); 1093 1094 thread_idle = false; 1095 indirp = fss_bs_indir(sc, scp->fc_cluster); 1096 if (indirp != NULL) { 1097 error = fss_bs_io(sc, FSS_WRITE, sc->sc_clnext, 1098 0, FSS_CLSIZE(sc), scp->fc_data); 1099 } else 1100 error = EIO; 1101 1102 mutex_enter(&sc->sc_slock); 1103 if (error == 0) { 1104 *indirp = sc->sc_clnext++; 1105 sc->sc_indir_dirty = 1; 1106 } else 1107 fss_error(sc, "write error on backing store"); 1108 1109 scp->fc_type = FSS_CACHE_FREE; 1110 cv_signal(&sc->sc_cache_cv); 1111 break; 1112 } 1113 1114 /* 1115 * Process I/O requests 1116 */ 1117 if ((bp = bufq_get(sc->sc_bufq)) == NULL) 1118 continue; 1119 is_valid = FSS_ISVALID(sc); 1120 is_read = (bp->b_flags & B_READ); 1121 thread_idle = false; 1122 1123 if (!is_valid) { 1124 mutex_exit(&sc->sc_slock); 1125 1126 bp->b_error = ENXIO; 1127 bp->b_resid = bp->b_bcount; 1128 biodone(bp); 1129 1130 mutex_enter(&sc->sc_slock); 1131 continue; 1132 } 1133 1134 disk_busy(sc->sc_dkdev); 1135 1136 /* 1137 * First read from the snapshotted block device unless 1138 * this request is completely covered by backing store. 1139 */ 1140 1141 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); 1142 off = FSS_CLOFF(sc, dbtob(bp->b_blkno)); 1143 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); 1144 error = 0; 1145 bp->b_resid = 0; 1146 bp->b_error = 0; 1147 for (c = cl; c <= ch; c++) { 1148 if (isset(sc->sc_copied, c)) 1149 continue; 1150 mutex_exit(&sc->sc_slock); 1151 1152 /* Not on backing store, read from device. */ 1153 nbp = getiobuf(NULL, true); 1154 nbp->b_flags = B_READ; 1155 nbp->b_resid = nbp->b_bcount = bp->b_bcount; 1156 nbp->b_bufsize = bp->b_bcount; 1157 nbp->b_data = bp->b_data; 1158 nbp->b_blkno = bp->b_blkno; 1159 nbp->b_lblkno = 0; 1160 nbp->b_dev = sc->sc_bdev; 1161 SET(nbp->b_cflags, BC_BUSY); /* mark buffer busy */ 1162 1163 bdev_strategy(nbp); 1164 1165 error = biowait(nbp); 1166 if (error != 0) { 1167 bp->b_resid = bp->b_bcount; 1168 bp->b_error = nbp->b_error; 1169 disk_unbusy(sc->sc_dkdev, 0, is_read); 1170 biodone(bp); 1171 } 1172 putiobuf(nbp); 1173 1174 mutex_enter(&sc->sc_slock); 1175 break; 1176 } 1177 if (error) 1178 continue; 1179 1180 /* 1181 * Replace those parts that have been saved to backing store. 1182 */ 1183 1184 addr = bp->b_data; 1185 todo = bp->b_bcount; 1186 for (c = cl; c <= ch; c++, off = 0, todo -= len, addr += len) { 1187 len = FSS_CLSIZE(sc)-off; 1188 if (len > todo) 1189 len = todo; 1190 if (isclr(sc->sc_copied, c)) 1191 continue; 1192 mutex_exit(&sc->sc_slock); 1193 1194 indirp = fss_bs_indir(sc, c); 1195 if (indirp == NULL || *indirp == 0) { 1196 /* 1197 * Not on backing store. Either in cache 1198 * or hole in the snapshotted block device. 1199 */ 1200 1201 mutex_enter(&sc->sc_slock); 1202 for (scp = sc->sc_cache; scp < scl; scp++) 1203 if (scp->fc_type == FSS_CACHE_VALID && 1204 scp->fc_cluster == c) 1205 break; 1206 if (scp < scl) 1207 memcpy(addr, (char *)scp->fc_data+off, 1208 len); 1209 else 1210 memset(addr, 0, len); 1211 continue; 1212 } 1213 1214 /* 1215 * Read from backing store. 1216 */ 1217 error = 1218 fss_bs_io(sc, FSS_READ, *indirp, off, len, addr); 1219 1220 mutex_enter(&sc->sc_slock); 1221 if (error) { 1222 bp->b_resid = bp->b_bcount; 1223 bp->b_error = error; 1224 break; 1225 } 1226 } 1227 mutex_exit(&sc->sc_slock); 1228 1229 disk_unbusy(sc->sc_dkdev, (error ? 0 : bp->b_bcount), is_read); 1230 biodone(bp); 1231 1232 mutex_enter(&sc->sc_slock); 1233 } 1234 } 1235 1236 #ifdef _MODULE 1237 1238 #include <sys/module.h> 1239 1240 MODULE(MODULE_CLASS_DRIVER, fss, NULL); 1241 CFDRIVER_DECL(fss, DV_DISK, NULL); 1242 1243 static int 1244 fss_modcmd(modcmd_t cmd, void *arg) 1245 { 1246 int bmajor = -1, cmajor = -1, error = 0; 1247 1248 switch (cmd) { 1249 case MODULE_CMD_INIT: 1250 mutex_init(&fss_device_lock, MUTEX_DEFAULT, IPL_NONE); 1251 error = config_cfdriver_attach(&fss_cd); 1252 if (error) { 1253 mutex_destroy(&fss_device_lock); 1254 break; 1255 } 1256 error = config_cfattach_attach(fss_cd.cd_name, &fss_ca); 1257 if (error) { 1258 config_cfdriver_detach(&fss_cd); 1259 mutex_destroy(&fss_device_lock); 1260 break; 1261 } 1262 error = devsw_attach(fss_cd.cd_name, 1263 &fss_bdevsw, &bmajor, &fss_cdevsw, &cmajor); 1264 if (error) { 1265 config_cfattach_detach(fss_cd.cd_name, &fss_ca); 1266 config_cfdriver_detach(&fss_cd); 1267 mutex_destroy(&fss_device_lock); 1268 break; 1269 } 1270 break; 1271 1272 case MODULE_CMD_FINI: 1273 error = config_cfattach_detach(fss_cd.cd_name, &fss_ca); 1274 if (error) 1275 break; 1276 config_cfdriver_detach(&fss_cd); 1277 devsw_detach(&fss_bdevsw, &fss_cdevsw); 1278 mutex_destroy(&fss_device_lock); 1279 break; 1280 1281 default: 1282 error = ENOTTY; 1283 break; 1284 } 1285 1286 return error; 1287 } 1288 1289 #endif /* _MODULE */ 1290