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sys/dev/fss.c
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1 /* $NetBSD: fss.c,v 1.29.2.1 2007/03/04 14:26:51 bouyer 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * File system snapshot disk driver. 41 * 42 * Block/character interface to the snapshot of a mounted file system. 43 */ 44 45 #include <sys/cdefs.h> 46 __KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.29.2.1 2007/03/04 14:26:51 bouyer Exp $"); 47 48 #include "fss.h" 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 #include <sys/namei.h> 53 #include <sys/proc.h> 54 #include <sys/errno.h> 55 #include <sys/buf.h> 56 #include <sys/malloc.h> 57 #include <sys/ioctl.h> 58 #include <sys/disklabel.h> 59 #include <sys/device.h> 60 #include <sys/disk.h> 61 #include <sys/stat.h> 62 #include <sys/mount.h> 63 #include <sys/vnode.h> 64 #include <sys/file.h> 65 #include <sys/uio.h> 66 #include <sys/conf.h> 67 #include <sys/kthread.h> 68 69 #include <miscfs/specfs/specdev.h> 70 71 #include <dev/fssvar.h> 72 73 #include <machine/stdarg.h> 74 75 #ifdef DEBUG 76 #define FSS_STATISTICS 77 #endif 78 79 #ifdef FSS_STATISTICS 80 struct fss_stat { 81 u_int64_t cow_calls; 82 u_int64_t cow_copied; 83 u_int64_t cow_cache_full; 84 u_int64_t indir_read; 85 u_int64_t indir_write; 86 }; 87 88 static struct fss_stat fss_stat[NFSS]; 89 90 #define FSS_STAT_INC(sc, field) \ 91 do { \ 92 fss_stat[sc->sc_unit].field++; \ 93 } while (0) 94 #define FSS_STAT_SET(sc, field, value) \ 95 do { \ 96 fss_stat[sc->sc_unit].field = value; \ 97 } while (0) 98 #define FSS_STAT_ADD(sc, field, value) \ 99 do { \ 100 fss_stat[sc->sc_unit].field += value; \ 101 } while (0) 102 #define FSS_STAT_VAL(sc, field) fss_stat[sc->sc_unit].field 103 #define FSS_STAT_CLEAR(sc) \ 104 do { \ 105 memset(&fss_stat[sc->sc_unit], 0, \ 106 sizeof(struct fss_stat)); \ 107 } while (0) 108 #else /* FSS_STATISTICS */ 109 #define FSS_STAT_INC(sc, field) 110 #define FSS_STAT_SET(sc, field, value) 111 #define FSS_STAT_ADD(sc, field, value) 112 #define FSS_STAT_CLEAR(sc) 113 #endif /* FSS_STATISTICS */ 114 115 static struct fss_softc fss_softc[NFSS]; 116 117 void fssattach(int); 118 119 dev_type_open(fss_open); 120 dev_type_close(fss_close); 121 dev_type_read(fss_read); 122 dev_type_write(fss_write); 123 dev_type_ioctl(fss_ioctl); 124 dev_type_strategy(fss_strategy); 125 dev_type_dump(fss_dump); 126 dev_type_size(fss_size); 127 128 static int fss_copy_on_write(void *, struct buf *); 129 static inline void fss_error(struct fss_softc *, const char *, ...); 130 static int fss_create_files(struct fss_softc *, struct fss_set *, 131 off_t *, struct lwp *); 132 static int fss_create_snapshot(struct fss_softc *, struct fss_set *, 133 struct lwp *); 134 static int fss_delete_snapshot(struct fss_softc *, struct lwp *); 135 static int fss_softc_alloc(struct fss_softc *); 136 static void fss_softc_free(struct fss_softc *); 137 static void fss_cluster_iodone(struct buf *); 138 static void fss_read_cluster(struct fss_softc *, u_int32_t); 139 static void fss_bs_thread(void *); 140 static int fss_bs_io(struct fss_softc *, fss_io_type, 141 u_int32_t, off_t, int, caddr_t); 142 static u_int32_t *fss_bs_indir(struct fss_softc *, u_int32_t); 143 144 const struct bdevsw fss_bdevsw = { 145 fss_open, fss_close, fss_strategy, fss_ioctl, 146 fss_dump, fss_size, D_DISK 147 }; 148 149 const struct cdevsw fss_cdevsw = { 150 fss_open, fss_close, fss_read, fss_write, fss_ioctl, 151 nostop, notty, nopoll, nommap, nokqfilter, D_DISK 152 }; 153 154 void 155 fssattach(int num) 156 { 157 int i; 158 struct fss_softc *sc; 159 160 for (i = 0; i < NFSS; i++) { 161 sc = &fss_softc[i]; 162 sc->sc_unit = i; 163 sc->sc_bdev = NODEV; 164 simple_lock_init(&sc->sc_slock); 165 lockinit(&sc->sc_lock, PRIBIO, "fsslock", 0, 0); 166 bufq_alloc(&sc->sc_bufq, "fcfs", 0); 167 } 168 } 169 170 int 171 fss_open(dev_t dev, int flags, int mode, struct lwp *l) 172 { 173 int s, mflag; 174 struct fss_softc *sc; 175 176 mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN); 177 178 if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL) 179 return ENODEV; 180 181 FSS_LOCK(sc, s); 182 183 sc->sc_flags |= mflag; 184 185 FSS_UNLOCK(sc, s); 186 187 return 0; 188 } 189 190 int 191 fss_close(dev_t dev, int flags, int mode, struct lwp *l) 192 { 193 int s, mflag, error; 194 struct fss_softc *sc; 195 196 mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN); 197 198 if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL) 199 return ENODEV; 200 201 FSS_LOCK(sc, s); 202 203 if ((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) == mflag) { 204 if ((sc->sc_uflags & FSS_UNCONFIG_ON_CLOSE) != 0 && 205 (sc->sc_flags & FSS_ACTIVE) != 0) { 206 FSS_UNLOCK(sc, s); 207 error = fss_ioctl(dev, FSSIOCCLR, NULL, FWRITE, l); 208 if (error) 209 return error; 210 FSS_LOCK(sc, s); 211 } 212 sc->sc_uflags &= ~FSS_UNCONFIG_ON_CLOSE; 213 } 214 215 sc->sc_flags &= ~mflag; 216 217 FSS_UNLOCK(sc, s); 218 219 return 0; 220 } 221 222 void 223 fss_strategy(struct buf *bp) 224 { 225 int s; 226 struct fss_softc *sc; 227 228 sc = FSS_DEV_TO_SOFTC(bp->b_dev); 229 230 FSS_LOCK(sc, s); 231 232 if ((bp->b_flags & B_READ) != B_READ || 233 sc == NULL || !FSS_ISVALID(sc)) { 234 235 FSS_UNLOCK(sc, s); 236 237 bp->b_error = (sc == NULL ? ENODEV : EROFS); 238 bp->b_flags |= B_ERROR; 239 bp->b_resid = bp->b_bcount; 240 biodone(bp); 241 return; 242 } 243 244 bp->b_rawblkno = bp->b_blkno; 245 BUFQ_PUT(sc->sc_bufq, bp); 246 wakeup(&sc->sc_bs_proc); 247 248 FSS_UNLOCK(sc, s); 249 } 250 251 int 252 fss_read(dev_t dev, struct uio *uio, int flags) 253 { 254 return physio(fss_strategy, NULL, dev, B_READ, minphys, uio); 255 } 256 257 int 258 fss_write(dev_t dev, struct uio *uio, int flags) 259 { 260 return physio(fss_strategy, NULL, dev, B_WRITE, minphys, uio); 261 } 262 263 int 264 fss_ioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct lwp *l) 265 { 266 int error; 267 struct fss_softc *sc; 268 struct fss_set *fss = (struct fss_set *)data; 269 struct fss_get *fsg = (struct fss_get *)data; 270 271 if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL) 272 return ENODEV; 273 274 switch (cmd) { 275 case FSSIOCSET: 276 lockmgr(&sc->sc_lock, LK_EXCLUSIVE, NULL); 277 if ((flag & FWRITE) == 0) 278 error = EPERM; 279 else if ((sc->sc_flags & FSS_ACTIVE) != 0) 280 error = EBUSY; 281 else 282 error = fss_create_snapshot(sc, fss, l); 283 lockmgr(&sc->sc_lock, LK_RELEASE, NULL); 284 break; 285 286 case FSSIOCCLR: 287 lockmgr(&sc->sc_lock, LK_EXCLUSIVE, NULL); 288 if ((flag & FWRITE) == 0) 289 error = EPERM; 290 else if ((sc->sc_flags & FSS_ACTIVE) == 0) 291 error = ENXIO; 292 else 293 error = fss_delete_snapshot(sc, l); 294 lockmgr(&sc->sc_lock, LK_RELEASE, NULL); 295 break; 296 297 case FSSIOCGET: 298 lockmgr(&sc->sc_lock, LK_EXCLUSIVE, NULL); 299 switch (sc->sc_flags & (FSS_PERSISTENT | FSS_ACTIVE)) { 300 case FSS_ACTIVE: 301 memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN); 302 fsg->fsg_csize = FSS_CLSIZE(sc); 303 fsg->fsg_time = sc->sc_time; 304 fsg->fsg_mount_size = sc->sc_clcount; 305 fsg->fsg_bs_size = sc->sc_clnext; 306 error = 0; 307 break; 308 case FSS_PERSISTENT | FSS_ACTIVE: 309 memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN); 310 fsg->fsg_csize = 0; 311 fsg->fsg_time = sc->sc_time; 312 fsg->fsg_mount_size = 0; 313 fsg->fsg_bs_size = 0; 314 error = 0; 315 break; 316 default: 317 error = ENXIO; 318 break; 319 } 320 lockmgr(&sc->sc_lock, LK_RELEASE, NULL); 321 break; 322 323 case FSSIOFSET: 324 sc->sc_uflags = *(int *)data; 325 error = 0; 326 break; 327 328 case FSSIOFGET: 329 *(int *)data = sc->sc_uflags; 330 error = 0; 331 break; 332 333 default: 334 error = EINVAL; 335 break; 336 } 337 338 return error; 339 } 340 341 int 342 fss_size(dev_t dev) 343 { 344 return -1; 345 } 346 347 int 348 fss_dump(dev_t dev, daddr_t blkno, caddr_t va, 349 size_t size) 350 { 351 return EROFS; 352 } 353 354 /* 355 * An error occurred reading or writing the snapshot or backing store. 356 * If it is the first error log to console. 357 * The caller holds the simplelock. 358 */ 359 static inline void 360 fss_error(struct fss_softc *sc, const char *fmt, ...) 361 { 362 va_list ap; 363 364 if ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE) { 365 va_start(ap, fmt); 366 printf("fss%d: snapshot invalid: ", sc->sc_unit); 367 vprintf(fmt, ap); 368 printf("\n"); 369 va_end(ap); 370 } 371 if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE) 372 sc->sc_flags |= FSS_ERROR; 373 } 374 375 /* 376 * Allocate the variable sized parts of the softc and 377 * fork the kernel thread. 378 * 379 * The fields sc_clcount, sc_clshift, sc_cache_size and sc_indir_size 380 * must be initialized. 381 */ 382 static int 383 fss_softc_alloc(struct fss_softc *sc) 384 { 385 int i, len, error; 386 387 len = (sc->sc_clcount+NBBY-1)/NBBY; 388 sc->sc_copied = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 389 if (sc->sc_copied == NULL) 390 return(ENOMEM); 391 392 len = sc->sc_cache_size*sizeof(struct fss_cache); 393 sc->sc_cache = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 394 if (sc->sc_cache == NULL) 395 return(ENOMEM); 396 397 len = FSS_CLSIZE(sc); 398 for (i = 0; i < sc->sc_cache_size; i++) { 399 sc->sc_cache[i].fc_type = FSS_CACHE_FREE; 400 sc->sc_cache[i].fc_softc = sc; 401 sc->sc_cache[i].fc_xfercount = 0; 402 sc->sc_cache[i].fc_data = malloc(len, M_TEMP, 403 M_WAITOK|M_CANFAIL); 404 if (sc->sc_cache[i].fc_data == NULL) 405 return(ENOMEM); 406 } 407 408 len = (sc->sc_indir_size+NBBY-1)/NBBY; 409 sc->sc_indir_valid = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 410 if (sc->sc_indir_valid == NULL) 411 return(ENOMEM); 412 413 len = FSS_CLSIZE(sc); 414 sc->sc_indir_data = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 415 if (sc->sc_indir_data == NULL) 416 return(ENOMEM); 417 418 if ((error = kthread_create1(fss_bs_thread, sc, &sc->sc_bs_proc, 419 "fssbs%d", sc->sc_unit)) != 0) 420 return error; 421 422 sc->sc_flags |= FSS_BS_THREAD; 423 return 0; 424 } 425 426 /* 427 * Free the variable sized parts of the softc. 428 */ 429 static void 430 fss_softc_free(struct fss_softc *sc) 431 { 432 int s, i; 433 434 if ((sc->sc_flags & FSS_BS_THREAD) != 0) { 435 FSS_LOCK(sc, s); 436 sc->sc_flags &= ~FSS_BS_THREAD; 437 wakeup(&sc->sc_bs_proc); 438 while (sc->sc_bs_proc != NULL) 439 ltsleep(&sc->sc_bs_proc, PRIBIO, "fssthread", 0, 440 &sc->sc_slock); 441 FSS_UNLOCK(sc, s); 442 } 443 444 if (sc->sc_copied != NULL) 445 free(sc->sc_copied, M_TEMP); 446 sc->sc_copied = NULL; 447 448 if (sc->sc_cache != NULL) { 449 for (i = 0; i < sc->sc_cache_size; i++) 450 if (sc->sc_cache[i].fc_data != NULL) 451 free(sc->sc_cache[i].fc_data, M_TEMP); 452 free(sc->sc_cache, M_TEMP); 453 } 454 sc->sc_cache = NULL; 455 456 if (sc->sc_indir_valid != NULL) 457 free(sc->sc_indir_valid, M_TEMP); 458 sc->sc_indir_valid = NULL; 459 460 if (sc->sc_indir_data != NULL) 461 free(sc->sc_indir_data, M_TEMP); 462 sc->sc_indir_data = NULL; 463 } 464 465 /* 466 * Check if an unmount is ok. If forced, set this snapshot into ERROR state. 467 */ 468 int 469 fss_umount_hook(struct mount *mp, int forced) 470 { 471 int i, s; 472 473 for (i = 0; i < NFSS; i++) { 474 FSS_LOCK(&fss_softc[i], s); 475 if ((fss_softc[i].sc_flags & FSS_ACTIVE) != 0 && 476 fss_softc[i].sc_mount == mp) { 477 if (forced) 478 fss_error(&fss_softc[i], "forced unmount"); 479 else { 480 FSS_UNLOCK(&fss_softc[i], s); 481 return EBUSY; 482 } 483 } 484 FSS_UNLOCK(&fss_softc[i], s); 485 } 486 487 return 0; 488 } 489 490 /* 491 * A buffer is written to the snapshotted block device. Copy to 492 * backing store if needed. 493 */ 494 static int 495 fss_copy_on_write(void *v, struct buf *bp) 496 { 497 int s; 498 u_int32_t cl, ch, c; 499 struct fss_softc *sc = v; 500 501 FSS_LOCK(sc, s); 502 if (!FSS_ISVALID(sc)) { 503 FSS_UNLOCK(sc, s); 504 return 0; 505 } 506 507 FSS_UNLOCK(sc, s); 508 509 FSS_STAT_INC(sc, cow_calls); 510 511 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); 512 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); 513 514 for (c = cl; c <= ch; c++) 515 fss_read_cluster(sc, c); 516 517 return 0; 518 } 519 520 /* 521 * Lookup and open needed files. 522 * 523 * For file system internal snapshot initializes sc_mntname, sc_mount, 524 * sc_bs_vp and sc_time. 525 * 526 * Otherwise returns dev and size of the underlying block device. 527 * Initializes sc_mntname, sc_mount_vp, sc_bdev, sc_bs_vp and sc_mount 528 */ 529 static int 530 fss_create_files(struct fss_softc *sc, struct fss_set *fss, 531 off_t *bsize, struct lwp *l) 532 { 533 int error, bits, fsbsize; 534 struct timespec ts; 535 struct partinfo dpart; 536 struct vattr va; 537 struct nameidata nd; 538 539 /* 540 * Get the mounted file system. 541 */ 542 543 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_mount, l); 544 if ((error = namei(&nd)) != 0) 545 return error; 546 547 if ((nd.ni_vp->v_flag & VROOT) != VROOT) { 548 vrele(nd.ni_vp); 549 return EINVAL; 550 } 551 552 sc->sc_mount = nd.ni_vp->v_mount; 553 memcpy(sc->sc_mntname, sc->sc_mount->mnt_stat.f_mntonname, MNAMELEN); 554 555 vrele(nd.ni_vp); 556 557 /* 558 * Check for file system internal snapshot. 559 */ 560 561 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l); 562 if ((error = namei(&nd)) != 0) 563 return error; 564 565 if (nd.ni_vp->v_type == VREG && nd.ni_vp->v_mount == sc->sc_mount) { 566 vrele(nd.ni_vp); 567 sc->sc_flags |= FSS_PERSISTENT; 568 569 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l); 570 if ((error = vn_open(&nd, FREAD, 0)) != 0) 571 return error; 572 sc->sc_bs_vp = nd.ni_vp; 573 574 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; 575 bits = sizeof(sc->sc_bs_bshift)*NBBY; 576 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < bits; 577 sc->sc_bs_bshift++) 578 if (FSS_FSBSIZE(sc) == fsbsize) 579 break; 580 if (sc->sc_bs_bshift >= bits) { 581 VOP_UNLOCK(sc->sc_bs_vp, 0); 582 return EINVAL; 583 } 584 585 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 586 sc->sc_clshift = 0; 587 588 error = VFS_SNAPSHOT(sc->sc_mount, sc->sc_bs_vp, &ts); 589 TIMESPEC_TO_TIMEVAL(&sc->sc_time, &ts); 590 591 VOP_UNLOCK(sc->sc_bs_vp, 0); 592 593 return error; 594 } 595 vrele(nd.ni_vp); 596 597 /* 598 * Get the block device it is mounted on. 599 */ 600 601 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, 602 sc->sc_mount->mnt_stat.f_mntfromname, l); 603 if ((error = namei(&nd)) != 0) 604 return error; 605 606 if (nd.ni_vp->v_type != VBLK) { 607 vrele(nd.ni_vp); 608 return EINVAL; 609 } 610 611 error = VOP_IOCTL(nd.ni_vp, DIOCGPART, &dpart, FREAD, 612 l->l_cred, l); 613 if (error) { 614 vrele(nd.ni_vp); 615 return error; 616 } 617 618 sc->sc_mount_vp = nd.ni_vp; 619 sc->sc_bdev = nd.ni_vp->v_rdev; 620 *bsize = (off_t)dpart.disklab->d_secsize*dpart.part->p_size; 621 vrele(nd.ni_vp); 622 623 /* 624 * Get the backing store 625 */ 626 627 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l); 628 if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0) 629 return error; 630 VOP_UNLOCK(nd.ni_vp, 0); 631 632 sc->sc_bs_vp = nd.ni_vp; 633 634 if (nd.ni_vp->v_type != VREG && nd.ni_vp->v_type != VCHR) 635 return EINVAL; 636 637 if (sc->sc_bs_vp->v_type == VREG) { 638 error = VOP_GETATTR(sc->sc_bs_vp, &va, l->l_cred, l); 639 if (error != 0) 640 return error; 641 sc->sc_bs_size = va.va_size; 642 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; 643 if (fsbsize & (fsbsize-1)) /* No power of two */ 644 return EINVAL; 645 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < 32; 646 sc->sc_bs_bshift++) 647 if (FSS_FSBSIZE(sc) == fsbsize) 648 break; 649 if (sc->sc_bs_bshift >= 32) 650 return EINVAL; 651 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 652 } else { 653 sc->sc_bs_bshift = DEV_BSHIFT; 654 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 655 } 656 657 /* 658 * As all IO to from/to the backing store goes through 659 * VOP_STRATEGY() clean the buffer cache to prevent 660 * cache incoherencies. 661 */ 662 if ((error = vinvalbuf(sc->sc_bs_vp, V_SAVE, l->l_cred, l, 0, 0)) != 0) 663 return error; 664 665 return 0; 666 } 667 668 /* 669 * Create a snapshot. 670 */ 671 static int 672 fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct lwp *l) 673 { 674 int len, error; 675 u_int32_t csize; 676 off_t bsize; 677 678 bsize = 0; /* XXX gcc */ 679 680 /* 681 * Open needed files. 682 */ 683 if ((error = fss_create_files(sc, fss, &bsize, l)) != 0) 684 goto bad; 685 686 if (sc->sc_flags & FSS_PERSISTENT) { 687 fss_softc_alloc(sc); 688 sc->sc_flags |= FSS_ACTIVE; 689 return 0; 690 } 691 692 /* 693 * Set cluster size. Must be a power of two and 694 * a multiple of backing store block size. 695 */ 696 if (fss->fss_csize <= 0) 697 csize = MAXPHYS; 698 else 699 csize = fss->fss_csize; 700 if (bsize/csize > FSS_CLUSTER_MAX) 701 csize = bsize/FSS_CLUSTER_MAX+1; 702 703 for (sc->sc_clshift = sc->sc_bs_bshift; sc->sc_clshift < 32; 704 sc->sc_clshift++) 705 if (FSS_CLSIZE(sc) >= csize) 706 break; 707 if (sc->sc_clshift >= 32) { 708 error = EINVAL; 709 goto bad; 710 } 711 sc->sc_clmask = FSS_CLSIZE(sc)-1; 712 713 /* 714 * Set number of cache slots. 715 */ 716 if (FSS_CLSIZE(sc) <= 8192) 717 sc->sc_cache_size = 32; 718 else if (FSS_CLSIZE(sc) <= 65536) 719 sc->sc_cache_size = 8; 720 else 721 sc->sc_cache_size = 4; 722 723 /* 724 * Set number of clusters and size of last cluster. 725 */ 726 sc->sc_clcount = FSS_BTOCL(sc, bsize-1)+1; 727 sc->sc_clresid = FSS_CLOFF(sc, bsize-1)+1; 728 729 /* 730 * Set size of indirect table. 731 */ 732 len = sc->sc_clcount*sizeof(u_int32_t); 733 sc->sc_indir_size = FSS_BTOCL(sc, len)+1; 734 sc->sc_clnext = sc->sc_indir_size; 735 sc->sc_indir_cur = 0; 736 737 if ((error = fss_softc_alloc(sc)) != 0) 738 goto bad; 739 740 /* 741 * Activate the snapshot. 742 */ 743 744 if ((error = vfs_write_suspend(sc->sc_mount, PUSER|PCATCH, 0)) != 0) 745 goto bad; 746 747 microtime(&sc->sc_time); 748 749 if (error == 0) 750 error = vn_cow_establish(sc->sc_mount_vp, 751 fss_copy_on_write, sc); 752 if (error == 0) 753 sc->sc_flags |= FSS_ACTIVE; 754 755 vfs_write_resume(sc->sc_mount); 756 757 if (error != 0) 758 goto bad; 759 760 #ifdef DEBUG 761 printf("fss%d: %s snapshot active\n", sc->sc_unit, sc->sc_mntname); 762 printf("fss%d: %u clusters of %u, %u cache slots, %u indir clusters\n", 763 sc->sc_unit, sc->sc_clcount, FSS_CLSIZE(sc), 764 sc->sc_cache_size, sc->sc_indir_size); 765 #endif 766 767 return 0; 768 769 bad: 770 fss_softc_free(sc); 771 if (sc->sc_bs_vp != NULL) { 772 if (sc->sc_flags & FSS_PERSISTENT) 773 vn_close(sc->sc_bs_vp, FREAD, l->l_cred, l); 774 else 775 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred, l); 776 } 777 sc->sc_bs_vp = NULL; 778 779 return error; 780 } 781 782 /* 783 * Delete a snapshot. 784 */ 785 static int 786 fss_delete_snapshot(struct fss_softc *sc, struct lwp *l) 787 { 788 int s; 789 790 if ((sc->sc_flags & FSS_PERSISTENT) == 0) 791 vn_cow_disestablish(sc->sc_mount_vp, fss_copy_on_write, sc); 792 793 FSS_LOCK(sc, s); 794 sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR); 795 sc->sc_mount = NULL; 796 sc->sc_bdev = NODEV; 797 FSS_UNLOCK(sc, s); 798 799 fss_softc_free(sc); 800 if (sc->sc_flags & FSS_PERSISTENT) 801 vn_close(sc->sc_bs_vp, FREAD, l->l_cred, l); 802 else 803 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred, l); 804 sc->sc_bs_vp = NULL; 805 sc->sc_flags &= ~FSS_PERSISTENT; 806 807 FSS_STAT_CLEAR(sc); 808 809 return 0; 810 } 811 812 /* 813 * A read from the snapshotted block device has completed. 814 */ 815 static void 816 fss_cluster_iodone(struct buf *bp) 817 { 818 int s; 819 struct fss_cache *scp = bp->b_private; 820 821 KASSERT(bp->b_vp == NULL); 822 823 FSS_LOCK(scp->fc_softc, s); 824 825 if (bp->b_flags & B_ERROR) 826 fss_error(scp->fc_softc, "fs read error %d", bp->b_error); 827 828 if (--scp->fc_xfercount == 0) 829 wakeup(&scp->fc_data); 830 831 FSS_UNLOCK(scp->fc_softc, s); 832 833 putiobuf(bp); 834 } 835 836 /* 837 * Read a cluster from the snapshotted block device to the cache. 838 */ 839 static void 840 fss_read_cluster(struct fss_softc *sc, u_int32_t cl) 841 { 842 int s, todo, len; 843 caddr_t addr; 844 daddr_t dblk; 845 struct buf *bp; 846 struct fss_cache *scp, *scl; 847 848 /* 849 * Get a free cache slot. 850 */ 851 scl = sc->sc_cache+sc->sc_cache_size; 852 853 FSS_LOCK(sc, s); 854 855 restart: 856 if (isset(sc->sc_copied, cl) || !FSS_ISVALID(sc)) { 857 FSS_UNLOCK(sc, s); 858 return; 859 } 860 861 for (scp = sc->sc_cache; scp < scl; scp++) 862 if (scp->fc_type != FSS_CACHE_FREE && 863 scp->fc_cluster == cl) { 864 ltsleep(&scp->fc_type, PRIBIO, "cowwait2", 0, 865 &sc->sc_slock); 866 goto restart; 867 } 868 869 for (scp = sc->sc_cache; scp < scl; scp++) 870 if (scp->fc_type == FSS_CACHE_FREE) { 871 scp->fc_type = FSS_CACHE_BUSY; 872 scp->fc_cluster = cl; 873 break; 874 } 875 if (scp >= scl) { 876 FSS_STAT_INC(sc, cow_cache_full); 877 ltsleep(&sc->sc_cache, PRIBIO, "cowwait3", 0, &sc->sc_slock); 878 goto restart; 879 } 880 881 FSS_UNLOCK(sc, s); 882 883 /* 884 * Start the read. 885 */ 886 FSS_STAT_INC(sc, cow_copied); 887 888 dblk = btodb(FSS_CLTOB(sc, cl)); 889 addr = scp->fc_data; 890 if (cl == sc->sc_clcount-1) { 891 todo = sc->sc_clresid; 892 memset(addr+todo, 0, FSS_CLSIZE(sc)-todo); 893 } else 894 todo = FSS_CLSIZE(sc); 895 while (todo > 0) { 896 len = todo; 897 if (len > MAXPHYS) 898 len = MAXPHYS; 899 900 bp = getiobuf(); 901 bp->b_flags = B_READ|B_CALL; 902 bp->b_bcount = len; 903 bp->b_bufsize = bp->b_bcount; 904 bp->b_error = 0; 905 bp->b_data = addr; 906 bp->b_blkno = dblk; 907 bp->b_proc = NULL; 908 bp->b_dev = sc->sc_bdev; 909 bp->b_vp = NULLVP; 910 bp->b_private = scp; 911 bp->b_iodone = fss_cluster_iodone; 912 913 DEV_STRATEGY(bp); 914 915 FSS_LOCK(sc, s); 916 scp->fc_xfercount++; 917 FSS_UNLOCK(sc, s); 918 919 dblk += btodb(len); 920 addr += len; 921 todo -= len; 922 } 923 924 /* 925 * Wait for all read requests to complete. 926 */ 927 FSS_LOCK(sc, s); 928 while (scp->fc_xfercount > 0) 929 ltsleep(&scp->fc_data, PRIBIO, "cowwait", 0, &sc->sc_slock); 930 931 scp->fc_type = FSS_CACHE_VALID; 932 setbit(sc->sc_copied, scp->fc_cluster); 933 FSS_UNLOCK(sc, s); 934 935 wakeup(&sc->sc_bs_proc); 936 } 937 938 /* 939 * Read/write clusters from/to backing store. 940 * For persistent snapshots must be called with cl == 0. off is the 941 * offset into the snapshot. 942 */ 943 static int 944 fss_bs_io(struct fss_softc *sc, fss_io_type rw, 945 u_int32_t cl, off_t off, int len, caddr_t data) 946 { 947 int error; 948 949 off += FSS_CLTOB(sc, cl); 950 951 vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY); 952 953 error = vn_rdwr((rw == FSS_READ ? UIO_READ : UIO_WRITE), sc->sc_bs_vp, 954 data, len, off, UIO_SYSSPACE, IO_UNIT|IO_NODELOCKED, 955 sc->sc_bs_proc->p_cred, NULL, NULL); 956 if (error == 0) { 957 simple_lock(&sc->sc_bs_vp->v_interlock); 958 error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(off), 959 round_page(off+len), PGO_CLEANIT|PGO_SYNCIO|PGO_FREE); 960 } 961 962 VOP_UNLOCK(sc->sc_bs_vp, 0); 963 964 return error; 965 } 966 967 /* 968 * Get a pointer to the indirect slot for this cluster. 969 */ 970 static u_int32_t * 971 fss_bs_indir(struct fss_softc *sc, u_int32_t cl) 972 { 973 u_int32_t icl; 974 int ioff; 975 976 icl = cl/(FSS_CLSIZE(sc)/sizeof(u_int32_t)); 977 ioff = cl%(FSS_CLSIZE(sc)/sizeof(u_int32_t)); 978 979 if (sc->sc_indir_cur == icl) 980 return &sc->sc_indir_data[ioff]; 981 982 if (sc->sc_indir_dirty) { 983 FSS_STAT_INC(sc, indir_write); 984 if (fss_bs_io(sc, FSS_WRITE, sc->sc_indir_cur, 0, 985 FSS_CLSIZE(sc), (caddr_t)sc->sc_indir_data) != 0) 986 return NULL; 987 setbit(sc->sc_indir_valid, sc->sc_indir_cur); 988 } 989 990 sc->sc_indir_dirty = 0; 991 sc->sc_indir_cur = icl; 992 993 if (isset(sc->sc_indir_valid, sc->sc_indir_cur)) { 994 FSS_STAT_INC(sc, indir_read); 995 if (fss_bs_io(sc, FSS_READ, sc->sc_indir_cur, 0, 996 FSS_CLSIZE(sc), (caddr_t)sc->sc_indir_data) != 0) 997 return NULL; 998 } else 999 memset(sc->sc_indir_data, 0, FSS_CLSIZE(sc)); 1000 1001 return &sc->sc_indir_data[ioff]; 1002 } 1003 1004 /* 1005 * The kernel thread (one for every active snapshot). 1006 * 1007 * After wakeup it cleans the cache and runs the I/O requests. 1008 */ 1009 static void 1010 fss_bs_thread(void *arg) 1011 { 1012 int error, len, nfreed, nio, s; 1013 long off; 1014 caddr_t addr; 1015 u_int32_t c, cl, ch, *indirp; 1016 struct buf *bp, *nbp; 1017 struct fss_softc *sc; 1018 struct fss_cache *scp, *scl; 1019 1020 sc = arg; 1021 1022 scl = sc->sc_cache+sc->sc_cache_size; 1023 1024 nbp = getiobuf(); 1025 1026 nfreed = nio = 1; /* Dont sleep the first time */ 1027 1028 FSS_LOCK(sc, s); 1029 1030 for (;;) { 1031 if (nfreed == 0 && nio == 0) 1032 ltsleep(&sc->sc_bs_proc, PVM-1, "fssbs", 0, 1033 &sc->sc_slock); 1034 1035 if ((sc->sc_flags & FSS_BS_THREAD) == 0) { 1036 sc->sc_bs_proc = NULL; 1037 wakeup(&sc->sc_bs_proc); 1038 1039 FSS_UNLOCK(sc, s); 1040 1041 putiobuf(nbp); 1042 #ifdef FSS_STATISTICS 1043 if ((sc->sc_flags & FSS_PERSISTENT) == 0) { 1044 printf("fss%d: cow called %" PRId64 " times," 1045 " copied %" PRId64 " clusters," 1046 " cache full %" PRId64 " times\n", 1047 sc->sc_unit, 1048 FSS_STAT_VAL(sc, cow_calls), 1049 FSS_STAT_VAL(sc, cow_copied), 1050 FSS_STAT_VAL(sc, cow_cache_full)); 1051 printf("fss%d: %" PRId64 " indir reads," 1052 " %" PRId64 " indir writes\n", 1053 sc->sc_unit, 1054 FSS_STAT_VAL(sc, indir_read), 1055 FSS_STAT_VAL(sc, indir_write)); 1056 } 1057 #endif /* FSS_STATISTICS */ 1058 kthread_exit(0); 1059 } 1060 1061 /* 1062 * Process I/O requests (persistent) 1063 */ 1064 1065 if (sc->sc_flags & FSS_PERSISTENT) { 1066 nfreed = nio = 0; 1067 1068 if ((bp = BUFQ_GET(sc->sc_bufq)) == NULL) 1069 continue; 1070 1071 nio++; 1072 1073 if (FSS_ISVALID(sc)) { 1074 FSS_UNLOCK(sc, s); 1075 1076 error = fss_bs_io(sc, FSS_READ, 0, 1077 dbtob(bp->b_blkno), bp->b_bcount, 1078 bp->b_data); 1079 1080 FSS_LOCK(sc, s); 1081 } else 1082 error = ENXIO; 1083 1084 if (error) { 1085 bp->b_error = error; 1086 bp->b_flags |= B_ERROR; 1087 bp->b_resid = bp->b_bcount; 1088 } else 1089 bp->b_resid = 0; 1090 1091 biodone(bp); 1092 1093 continue; 1094 } 1095 1096 /* 1097 * Clean the cache 1098 */ 1099 nfreed = 0; 1100 for (scp = sc->sc_cache; scp < scl; scp++) { 1101 if (scp->fc_type != FSS_CACHE_VALID) 1102 continue; 1103 1104 FSS_UNLOCK(sc, s); 1105 1106 indirp = fss_bs_indir(sc, scp->fc_cluster); 1107 if (indirp != NULL) { 1108 error = fss_bs_io(sc, FSS_WRITE, sc->sc_clnext, 1109 0, FSS_CLSIZE(sc), scp->fc_data); 1110 } else 1111 error = EIO; 1112 1113 FSS_LOCK(sc, s); 1114 1115 if (error == 0) { 1116 *indirp = sc->sc_clnext++; 1117 sc->sc_indir_dirty = 1; 1118 } else 1119 fss_error(sc, "write bs error %d", error); 1120 1121 scp->fc_type = FSS_CACHE_FREE; 1122 nfreed++; 1123 wakeup(&scp->fc_type); 1124 } 1125 1126 if (nfreed) 1127 wakeup(&sc->sc_cache); 1128 1129 /* 1130 * Process I/O requests 1131 */ 1132 nio = 0; 1133 1134 if ((bp = BUFQ_GET(sc->sc_bufq)) == NULL) 1135 continue; 1136 1137 nio++; 1138 1139 if (!FSS_ISVALID(sc)) { 1140 bp->b_error = ENXIO; 1141 bp->b_flags |= B_ERROR; 1142 bp->b_resid = bp->b_bcount; 1143 biodone(bp); 1144 continue; 1145 } 1146 1147 /* 1148 * First read from the snapshotted block device. 1149 * XXX Split to only read those parts that have not 1150 * been saved to backing store? 1151 */ 1152 1153 FSS_UNLOCK(sc, s); 1154 1155 BUF_INIT(nbp); 1156 nbp->b_flags = B_READ; 1157 nbp->b_bcount = bp->b_bcount; 1158 nbp->b_bufsize = bp->b_bcount; 1159 nbp->b_error = 0; 1160 nbp->b_data = bp->b_data; 1161 nbp->b_blkno = bp->b_blkno; 1162 nbp->b_proc = bp->b_proc; 1163 nbp->b_dev = sc->sc_bdev; 1164 nbp->b_vp = NULLVP; 1165 1166 DEV_STRATEGY(nbp); 1167 1168 if (biowait(nbp) != 0) { 1169 bp->b_resid = bp->b_bcount; 1170 bp->b_error = nbp->b_error; 1171 bp->b_flags |= B_ERROR; 1172 biodone(bp); 1173 FSS_LOCK(sc, s); 1174 continue; 1175 } 1176 1177 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); 1178 off = FSS_CLOFF(sc, dbtob(bp->b_blkno)); 1179 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); 1180 bp->b_resid = bp->b_bcount; 1181 addr = bp->b_data; 1182 1183 FSS_LOCK(sc, s); 1184 1185 /* 1186 * Replace those parts that have been saved to backing store. 1187 */ 1188 1189 for (c = cl; c <= ch; 1190 c++, off = 0, bp->b_resid -= len, addr += len) { 1191 len = FSS_CLSIZE(sc)-off; 1192 if (len > bp->b_resid) 1193 len = bp->b_resid; 1194 1195 if (isclr(sc->sc_copied, c)) 1196 continue; 1197 1198 FSS_UNLOCK(sc, s); 1199 1200 indirp = fss_bs_indir(sc, c); 1201 1202 FSS_LOCK(sc, s); 1203 1204 if (indirp == NULL || *indirp == 0) { 1205 /* 1206 * Not on backing store. Either in cache 1207 * or hole in the snapshotted block device. 1208 */ 1209 for (scp = sc->sc_cache; scp < scl; scp++) 1210 if (scp->fc_type == FSS_CACHE_VALID && 1211 scp->fc_cluster == c) 1212 break; 1213 if (scp < scl) 1214 memcpy(addr, scp->fc_data+off, len); 1215 else 1216 memset(addr, 0, len); 1217 continue; 1218 } 1219 /* 1220 * Read from backing store. 1221 */ 1222 1223 FSS_UNLOCK(sc, s); 1224 1225 if ((error = fss_bs_io(sc, FSS_READ, *indirp, 1226 off, len, addr)) != 0) { 1227 bp->b_resid = bp->b_bcount; 1228 bp->b_error = error; 1229 bp->b_flags |= B_ERROR; 1230 FSS_LOCK(sc, s); 1231 break; 1232 } 1233 1234 FSS_LOCK(sc, s); 1235 1236 } 1237 1238 biodone(bp); 1239 } 1240 }
Cache object: 8e268facc0728614b58e015456ad0dbe
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