fss.c revision 1.24
1 /* $NetBSD: fss.c,v 1.24 2006/04/13 15:56:53 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 * 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 1.24 2006/04/13 15:56:53 hannken 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, size_t size) 349 { 350 return EROFS; 351 } 352 353 /* 354 * An error occurred reading or writing the snapshot or backing store. 355 * If it is the first error log to console. 356 * The caller holds the simplelock. 357 */ 358 static inline void 359 fss_error(struct fss_softc *sc, const char *fmt, ...) 360 { 361 va_list ap; 362 363 if ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE) { 364 va_start(ap, fmt); 365 printf("fss%d: snapshot invalid: ", sc->sc_unit); 366 vprintf(fmt, ap); 367 printf("\n"); 368 va_end(ap); 369 } 370 if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE) 371 sc->sc_flags |= FSS_ERROR; 372 } 373 374 /* 375 * Allocate the variable sized parts of the softc and 376 * fork the kernel thread. 377 * 378 * The fields sc_clcount, sc_clshift, sc_cache_size and sc_indir_size 379 * must be initialized. 380 */ 381 static int 382 fss_softc_alloc(struct fss_softc *sc) 383 { 384 int i, len, error; 385 386 len = (sc->sc_clcount+NBBY-1)/NBBY; 387 sc->sc_copied = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 388 if (sc->sc_copied == NULL) 389 return(ENOMEM); 390 391 len = sc->sc_cache_size*sizeof(struct fss_cache); 392 sc->sc_cache = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 393 if (sc->sc_cache == NULL) 394 return(ENOMEM); 395 396 len = FSS_CLSIZE(sc); 397 for (i = 0; i < sc->sc_cache_size; i++) { 398 sc->sc_cache[i].fc_type = FSS_CACHE_FREE; 399 sc->sc_cache[i].fc_softc = sc; 400 sc->sc_cache[i].fc_xfercount = 0; 401 sc->sc_cache[i].fc_data = malloc(len, M_TEMP, 402 M_WAITOK|M_CANFAIL); 403 if (sc->sc_cache[i].fc_data == NULL) 404 return(ENOMEM); 405 } 406 407 len = (sc->sc_indir_size+NBBY-1)/NBBY; 408 sc->sc_indir_valid = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 409 if (sc->sc_indir_valid == NULL) 410 return(ENOMEM); 411 412 len = FSS_CLSIZE(sc); 413 sc->sc_indir_data = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL); 414 if (sc->sc_indir_data == NULL) 415 return(ENOMEM); 416 417 if ((error = kthread_create1(fss_bs_thread, sc, &sc->sc_bs_proc, 418 "fssbs%d", sc->sc_unit)) != 0) 419 return error; 420 421 sc->sc_flags |= FSS_BS_THREAD; 422 return 0; 423 } 424 425 /* 426 * Free the variable sized parts of the softc. 427 */ 428 static void 429 fss_softc_free(struct fss_softc *sc) 430 { 431 int s, i; 432 433 if ((sc->sc_flags & FSS_BS_THREAD) != 0) { 434 FSS_LOCK(sc, s); 435 sc->sc_flags &= ~FSS_BS_THREAD; 436 wakeup(&sc->sc_bs_proc); 437 while (sc->sc_bs_proc != NULL) 438 ltsleep(&sc->sc_bs_proc, PRIBIO, "fssthread", 0, 439 &sc->sc_slock); 440 FSS_UNLOCK(sc, s); 441 } 442 443 if (sc->sc_copied != NULL) 444 free(sc->sc_copied, M_TEMP); 445 sc->sc_copied = NULL; 446 447 if (sc->sc_cache != NULL) { 448 for (i = 0; i < sc->sc_cache_size; i++) 449 if (sc->sc_cache[i].fc_data != NULL) 450 free(sc->sc_cache[i].fc_data, M_TEMP); 451 free(sc->sc_cache, M_TEMP); 452 } 453 sc->sc_cache = NULL; 454 455 if (sc->sc_indir_valid != NULL) 456 free(sc->sc_indir_valid, M_TEMP); 457 sc->sc_indir_valid = NULL; 458 459 if (sc->sc_indir_data != NULL) 460 free(sc->sc_indir_data, M_TEMP); 461 sc->sc_indir_data = NULL; 462 } 463 464 /* 465 * Check if an unmount is ok. If forced, set this snapshot into ERROR state. 466 */ 467 int 468 fss_umount_hook(struct mount *mp, int forced) 469 { 470 int i, s; 471 472 for (i = 0; i < NFSS; i++) { 473 FSS_LOCK(&fss_softc[i], s); 474 if ((fss_softc[i].sc_flags & FSS_ACTIVE) != 0 && 475 fss_softc[i].sc_mount == mp) { 476 if (forced) 477 fss_error(&fss_softc[i], "forced unmount"); 478 else { 479 FSS_UNLOCK(&fss_softc[i], s); 480 return EBUSY; 481 } 482 } 483 FSS_UNLOCK(&fss_softc[i], s); 484 } 485 486 return 0; 487 } 488 489 /* 490 * A buffer is written to the snapshotted block device. Copy to 491 * backing store if needed. 492 */ 493 static int 494 fss_copy_on_write(void *v, struct buf *bp) 495 { 496 int s; 497 u_int32_t cl, ch, c; 498 struct fss_softc *sc = v; 499 500 FSS_LOCK(sc, s); 501 if (!FSS_ISVALID(sc)) { 502 FSS_UNLOCK(sc, s); 503 return 0; 504 } 505 506 FSS_UNLOCK(sc, s); 507 508 FSS_STAT_INC(sc, cow_calls); 509 510 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); 511 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); 512 513 for (c = cl; c <= ch; c++) 514 fss_read_cluster(sc, c); 515 516 return 0; 517 } 518 519 /* 520 * Lookup and open needed files. 521 * 522 * For file system internal snapshot initializes sc_mntname, sc_mount, 523 * sc_bs_vp and sc_time. 524 * 525 * Otherwise returns dev and size of the underlying block device. 526 * Initializes sc_mntname, sc_mount_vp, sc_bdev, sc_bs_vp and sc_mount 527 */ 528 static int 529 fss_create_files(struct fss_softc *sc, struct fss_set *fss, 530 off_t *bsize, struct lwp *l) 531 { 532 int error, bits, fsbsize; 533 struct timespec ts; 534 struct partinfo dpart; 535 struct vattr va; 536 struct nameidata nd; 537 538 /* 539 * Get the mounted file system. 540 */ 541 542 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_mount, l); 543 if ((error = namei(&nd)) != 0) 544 return error; 545 546 if ((nd.ni_vp->v_flag & VROOT) != VROOT) { 547 vrele(nd.ni_vp); 548 return EINVAL; 549 } 550 551 sc->sc_mount = nd.ni_vp->v_mount; 552 memcpy(sc->sc_mntname, sc->sc_mount->mnt_stat.f_mntonname, MNAMELEN); 553 554 vrele(nd.ni_vp); 555 556 /* 557 * Check for file system internal snapshot. 558 */ 559 560 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l); 561 if ((error = namei(&nd)) != 0) 562 return error; 563 564 if (nd.ni_vp->v_type == VREG && nd.ni_vp->v_mount == sc->sc_mount) { 565 vrele(nd.ni_vp); 566 sc->sc_flags |= FSS_PERSISTENT; 567 568 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l); 569 if ((error = vn_open(&nd, FREAD, 0)) != 0) 570 return error; 571 sc->sc_bs_vp = nd.ni_vp; 572 573 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; 574 bits = sizeof(sc->sc_bs_bshift)*NBBY; 575 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < bits; 576 sc->sc_bs_bshift++) 577 if (FSS_FSBSIZE(sc) == fsbsize) 578 break; 579 if (sc->sc_bs_bshift >= bits) { 580 VOP_UNLOCK(sc->sc_bs_vp, 0); 581 return EINVAL; 582 } 583 584 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 585 sc->sc_clshift = 0; 586 587 error = VFS_SNAPSHOT(sc->sc_mount, sc->sc_bs_vp, &ts); 588 TIMESPEC_TO_TIMEVAL(&sc->sc_time, &ts); 589 590 VOP_UNLOCK(sc->sc_bs_vp, 0); 591 592 return error; 593 } 594 vrele(nd.ni_vp); 595 596 /* 597 * Get the block device it is mounted on. 598 */ 599 600 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, 601 sc->sc_mount->mnt_stat.f_mntfromname, l); 602 if ((error = namei(&nd)) != 0) 603 return error; 604 605 if (nd.ni_vp->v_type != VBLK) { 606 vrele(nd.ni_vp); 607 return EINVAL; 608 } 609 610 error = VOP_IOCTL(nd.ni_vp, DIOCGPART, &dpart, FREAD, 611 l->l_proc->p_ucred, l); 612 if (error) { 613 vrele(nd.ni_vp); 614 return error; 615 } 616 617 sc->sc_mount_vp = nd.ni_vp; 618 sc->sc_bdev = nd.ni_vp->v_rdev; 619 *bsize = (off_t)dpart.disklab->d_secsize*dpart.part->p_size; 620 vrele(nd.ni_vp); 621 622 /* 623 * Get the backing store 624 */ 625 626 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l); 627 if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0) 628 return error; 629 VOP_UNLOCK(nd.ni_vp, 0); 630 631 sc->sc_bs_vp = nd.ni_vp; 632 633 if (nd.ni_vp->v_type != VREG && nd.ni_vp->v_type != VCHR) 634 return EINVAL; 635 636 if (sc->sc_bs_vp->v_type == VREG) { 637 error = VOP_GETATTR(sc->sc_bs_vp, &va, l->l_proc->p_ucred, l); 638 if (error != 0) 639 return error; 640 sc->sc_bs_size = va.va_size; 641 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize; 642 if (fsbsize & (fsbsize-1)) /* No power of two */ 643 return EINVAL; 644 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < 32; 645 sc->sc_bs_bshift++) 646 if (FSS_FSBSIZE(sc) == fsbsize) 647 break; 648 if (sc->sc_bs_bshift >= 32) 649 return EINVAL; 650 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 651 } else { 652 sc->sc_bs_bshift = DEV_BSHIFT; 653 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1; 654 } 655 656 /* 657 * As all IO to from/to the backing store goes through 658 * VOP_STRATEGY() clean the buffer cache to prevent 659 * cache incoherencies. 660 */ 661 if ((error = vinvalbuf(sc->sc_bs_vp, V_SAVE, l->l_proc->p_ucred, l, 0, 0)) != 0) 662 return error; 663 664 return 0; 665 } 666 667 /* 668 * Create a snapshot. 669 */ 670 static int 671 fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct lwp *l) 672 { 673 int len, error; 674 u_int32_t csize; 675 off_t bsize; 676 677 /* 678 * Open needed files. 679 */ 680 if ((error = fss_create_files(sc, fss, &bsize, l)) != 0) 681 goto bad; 682 683 if (sc->sc_flags & FSS_PERSISTENT) { 684 fss_softc_alloc(sc); 685 sc->sc_flags |= FSS_ACTIVE; 686 return 0; 687 } 688 689 /* 690 * Set cluster size. Must be a power of two and 691 * a multiple of backing store block size. 692 */ 693 if (fss->fss_csize <= 0) 694 csize = MAXPHYS; 695 else 696 csize = fss->fss_csize; 697 if (bsize/csize > FSS_CLUSTER_MAX) 698 csize = bsize/FSS_CLUSTER_MAX+1; 699 700 for (sc->sc_clshift = sc->sc_bs_bshift; sc->sc_clshift < 32; 701 sc->sc_clshift++) 702 if (FSS_CLSIZE(sc) >= csize) 703 break; 704 if (sc->sc_clshift >= 32) { 705 error = EINVAL; 706 goto bad; 707 } 708 sc->sc_clmask = FSS_CLSIZE(sc)-1; 709 710 /* 711 * Set number of cache slots. 712 */ 713 if (FSS_CLSIZE(sc) <= 8192) 714 sc->sc_cache_size = 32; 715 else if (FSS_CLSIZE(sc) <= 65536) 716 sc->sc_cache_size = 8; 717 else 718 sc->sc_cache_size = 4; 719 720 /* 721 * Set number of clusters and size of last cluster. 722 */ 723 sc->sc_clcount = FSS_BTOCL(sc, bsize-1)+1; 724 sc->sc_clresid = FSS_CLOFF(sc, bsize-1)+1; 725 726 /* 727 * Set size of indirect table. 728 */ 729 len = sc->sc_clcount*sizeof(u_int32_t); 730 sc->sc_indir_size = FSS_BTOCL(sc, len)+1; 731 sc->sc_clnext = sc->sc_indir_size; 732 sc->sc_indir_cur = 0; 733 734 if ((error = fss_softc_alloc(sc)) != 0) 735 goto bad; 736 737 /* 738 * Activate the snapshot. 739 */ 740 741 if ((error = vfs_write_suspend(sc->sc_mount, PUSER|PCATCH, 0)) != 0) 742 goto bad; 743 744 microtime(&sc->sc_time); 745 746 if (error == 0) 747 error = vn_cow_establish(sc->sc_mount_vp, 748 fss_copy_on_write, sc); 749 if (error == 0) 750 sc->sc_flags |= FSS_ACTIVE; 751 752 vfs_write_resume(sc->sc_mount); 753 754 if (error != 0) 755 goto bad; 756 757 #ifdef DEBUG 758 printf("fss%d: %s snapshot active\n", sc->sc_unit, sc->sc_mntname); 759 printf("fss%d: %u clusters of %u, %u cache slots, %u indir clusters\n", 760 sc->sc_unit, sc->sc_clcount, FSS_CLSIZE(sc), 761 sc->sc_cache_size, sc->sc_indir_size); 762 #endif 763 764 return 0; 765 766 bad: 767 fss_softc_free(sc); 768 if (sc->sc_bs_vp != NULL) { 769 if (sc->sc_flags & FSS_PERSISTENT) 770 vn_close(sc->sc_bs_vp, FREAD, l->l_proc->p_ucred, l); 771 else 772 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_proc->p_ucred, l); 773 } 774 sc->sc_bs_vp = NULL; 775 776 return error; 777 } 778 779 /* 780 * Delete a snapshot. 781 */ 782 static int 783 fss_delete_snapshot(struct fss_softc *sc, struct lwp *l) 784 { 785 int s; 786 787 if ((sc->sc_flags & FSS_PERSISTENT) == 0) 788 vn_cow_disestablish(sc->sc_mount_vp, fss_copy_on_write, sc); 789 790 FSS_LOCK(sc, s); 791 sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR); 792 sc->sc_mount = NULL; 793 sc->sc_bdev = NODEV; 794 FSS_UNLOCK(sc, s); 795 796 fss_softc_free(sc); 797 if (sc->sc_flags & FSS_PERSISTENT) 798 vn_close(sc->sc_bs_vp, FREAD, l->l_proc->p_ucred, l); 799 else 800 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_proc->p_ucred, l); 801 sc->sc_bs_vp = NULL; 802 sc->sc_flags &= ~FSS_PERSISTENT; 803 804 FSS_STAT_CLEAR(sc); 805 806 return 0; 807 } 808 809 /* 810 * A read from the snapshotted block device has completed. 811 */ 812 static void 813 fss_cluster_iodone(struct buf *bp) 814 { 815 int s; 816 struct fss_cache *scp = bp->b_private; 817 818 KASSERT(bp->b_vp == NULL); 819 820 FSS_LOCK(scp->fc_softc, s); 821 822 if (bp->b_flags & B_ERROR) 823 fss_error(scp->fc_softc, "fs read error %d", bp->b_error); 824 825 if (--scp->fc_xfercount == 0) 826 wakeup(&scp->fc_data); 827 828 FSS_UNLOCK(scp->fc_softc, s); 829 830 putiobuf(bp); 831 } 832 833 /* 834 * Read a cluster from the snapshotted block device to the cache. 835 */ 836 static void 837 fss_read_cluster(struct fss_softc *sc, u_int32_t cl) 838 { 839 int s, todo, len; 840 caddr_t addr; 841 daddr_t dblk; 842 struct buf *bp; 843 struct fss_cache *scp, *scl; 844 845 /* 846 * Get a free cache slot. 847 */ 848 scl = sc->sc_cache+sc->sc_cache_size; 849 850 FSS_LOCK(sc, s); 851 852 restart: 853 if (isset(sc->sc_copied, cl) || !FSS_ISVALID(sc)) { 854 FSS_UNLOCK(sc, s); 855 return; 856 } 857 858 for (scp = sc->sc_cache; scp < scl; scp++) 859 if (scp->fc_type != FSS_CACHE_FREE && 860 scp->fc_cluster == cl) { 861 ltsleep(&scp->fc_type, PRIBIO, "cowwait2", 0, 862 &sc->sc_slock); 863 goto restart; 864 } 865 866 for (scp = sc->sc_cache; scp < scl; scp++) 867 if (scp->fc_type == FSS_CACHE_FREE) { 868 scp->fc_type = FSS_CACHE_BUSY; 869 scp->fc_cluster = cl; 870 break; 871 } 872 if (scp >= scl) { 873 FSS_STAT_INC(sc, cow_cache_full); 874 ltsleep(&sc->sc_cache, PRIBIO, "cowwait3", 0, &sc->sc_slock); 875 goto restart; 876 } 877 878 FSS_UNLOCK(sc, s); 879 880 /* 881 * Start the read. 882 */ 883 FSS_STAT_INC(sc, cow_copied); 884 885 dblk = btodb(FSS_CLTOB(sc, cl)); 886 addr = scp->fc_data; 887 if (cl == sc->sc_clcount-1) { 888 todo = sc->sc_clresid; 889 memset(addr+todo, 0, FSS_CLSIZE(sc)-todo); 890 } else 891 todo = FSS_CLSIZE(sc); 892 while (todo > 0) { 893 len = todo; 894 if (len > MAXPHYS) 895 len = MAXPHYS; 896 897 bp = getiobuf(); 898 bp->b_flags = B_READ|B_CALL; 899 bp->b_bcount = len; 900 bp->b_bufsize = bp->b_bcount; 901 bp->b_error = 0; 902 bp->b_data = addr; 903 bp->b_blkno = dblk; 904 bp->b_proc = NULL; 905 bp->b_dev = sc->sc_bdev; 906 bp->b_vp = NULLVP; 907 bp->b_private = scp; 908 bp->b_iodone = fss_cluster_iodone; 909 910 DEV_STRATEGY(bp); 911 912 FSS_LOCK(sc, s); 913 scp->fc_xfercount++; 914 FSS_UNLOCK(sc, s); 915 916 dblk += btodb(len); 917 addr += len; 918 todo -= len; 919 } 920 921 /* 922 * Wait for all read requests to complete. 923 */ 924 FSS_LOCK(sc, s); 925 while (scp->fc_xfercount > 0) 926 ltsleep(&scp->fc_data, PRIBIO, "cowwait", 0, &sc->sc_slock); 927 928 scp->fc_type = FSS_CACHE_VALID; 929 setbit(sc->sc_copied, scp->fc_cluster); 930 FSS_UNLOCK(sc, s); 931 932 wakeup(&sc->sc_bs_proc); 933 } 934 935 /* 936 * Read/write clusters from/to backing store. 937 * For persistent snapshots must be called with cl == 0. off is the 938 * offset into the snapshot. 939 */ 940 static int 941 fss_bs_io(struct fss_softc *sc, fss_io_type rw, 942 u_int32_t cl, off_t off, int len, caddr_t data) 943 { 944 int error; 945 946 off += FSS_CLTOB(sc, cl); 947 948 vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY); 949 950 error = vn_rdwr((rw == FSS_READ ? UIO_READ : UIO_WRITE), sc->sc_bs_vp, 951 data, len, off, UIO_SYSSPACE, IO_UNIT|IO_NODELOCKED, 952 sc->sc_bs_proc->p_ucred, NULL, NULL); 953 if (error == 0) { 954 simple_lock(&sc->sc_bs_vp->v_interlock); 955 error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(off), 956 round_page(off+len), PGO_CLEANIT|PGO_SYNCIO|PGO_FREE); 957 } 958 959 VOP_UNLOCK(sc->sc_bs_vp, 0); 960 961 return error; 962 } 963 964 /* 965 * Get a pointer to the indirect slot for this cluster. 966 */ 967 static u_int32_t * 968 fss_bs_indir(struct fss_softc *sc, u_int32_t cl) 969 { 970 u_int32_t icl; 971 int ioff; 972 973 icl = cl/(FSS_CLSIZE(sc)/sizeof(u_int32_t)); 974 ioff = cl%(FSS_CLSIZE(sc)/sizeof(u_int32_t)); 975 976 if (sc->sc_indir_cur == icl) 977 return &sc->sc_indir_data[ioff]; 978 979 if (sc->sc_indir_dirty) { 980 FSS_STAT_INC(sc, indir_write); 981 if (fss_bs_io(sc, FSS_WRITE, sc->sc_indir_cur, 0, 982 FSS_CLSIZE(sc), (caddr_t)sc->sc_indir_data) != 0) 983 return NULL; 984 setbit(sc->sc_indir_valid, sc->sc_indir_cur); 985 } 986 987 sc->sc_indir_dirty = 0; 988 sc->sc_indir_cur = icl; 989 990 if (isset(sc->sc_indir_valid, sc->sc_indir_cur)) { 991 FSS_STAT_INC(sc, indir_read); 992 if (fss_bs_io(sc, FSS_READ, sc->sc_indir_cur, 0, 993 FSS_CLSIZE(sc), (caddr_t)sc->sc_indir_data) != 0) 994 return NULL; 995 } else 996 memset(sc->sc_indir_data, 0, FSS_CLSIZE(sc)); 997 998 return &sc->sc_indir_data[ioff]; 999 } 1000 1001 /* 1002 * The kernel thread (one for every active snapshot). 1003 * 1004 * After wakeup it cleans the cache and runs the I/O requests. 1005 */ 1006 static void 1007 fss_bs_thread(void *arg) 1008 { 1009 int error, len, nfreed, nio, s; 1010 long off; 1011 caddr_t addr; 1012 u_int32_t c, cl, ch, *indirp; 1013 struct buf *bp, *nbp; 1014 struct fss_softc *sc; 1015 struct fss_cache *scp, *scl; 1016 1017 sc = arg; 1018 1019 scl = sc->sc_cache+sc->sc_cache_size; 1020 1021 nbp = getiobuf(); 1022 1023 nfreed = nio = 1; /* Dont sleep the first time */ 1024 1025 FSS_LOCK(sc, s); 1026 1027 for (;;) { 1028 if (nfreed == 0 && nio == 0) 1029 ltsleep(&sc->sc_bs_proc, PVM-1, "fssbs", 0, 1030 &sc->sc_slock); 1031 1032 if ((sc->sc_flags & FSS_BS_THREAD) == 0) { 1033 sc->sc_bs_proc = NULL; 1034 wakeup(&sc->sc_bs_proc); 1035 1036 FSS_UNLOCK(sc, s); 1037 1038 putiobuf(nbp); 1039 #ifdef FSS_STATISTICS 1040 if ((sc->sc_flags & FSS_PERSISTENT) == 0) { 1041 printf("fss%d: cow called %" PRId64 " times," 1042 " copied %" PRId64 " clusters," 1043 " cache full %" PRId64 " times\n", 1044 sc->sc_unit, 1045 FSS_STAT_VAL(sc, cow_calls), 1046 FSS_STAT_VAL(sc, cow_copied), 1047 FSS_STAT_VAL(sc, cow_cache_full)); 1048 printf("fss%d: %" PRId64 " indir reads," 1049 " %" PRId64 " indir writes\n", 1050 sc->sc_unit, 1051 FSS_STAT_VAL(sc, indir_read), 1052 FSS_STAT_VAL(sc, indir_write)); 1053 } 1054 #endif /* FSS_STATISTICS */ 1055 kthread_exit(0); 1056 } 1057 1058 /* 1059 * Process I/O requests (persistent) 1060 */ 1061 1062 if (sc->sc_flags & FSS_PERSISTENT) { 1063 nfreed = nio = 0; 1064 1065 if ((bp = BUFQ_GET(sc->sc_bufq)) == NULL) 1066 continue; 1067 1068 nio++; 1069 1070 if (FSS_ISVALID(sc)) { 1071 FSS_UNLOCK(sc, s); 1072 1073 error = fss_bs_io(sc, FSS_READ, 0, 1074 dbtob(bp->b_blkno), bp->b_bcount, 1075 bp->b_data); 1076 1077 FSS_LOCK(sc, s); 1078 } else 1079 error = ENXIO; 1080 1081 if (error) { 1082 bp->b_error = error; 1083 bp->b_flags |= B_ERROR; 1084 bp->b_resid = bp->b_bcount; 1085 } 1086 biodone(bp); 1087 1088 continue; 1089 } 1090 1091 /* 1092 * Clean the cache 1093 */ 1094 nfreed = 0; 1095 for (scp = sc->sc_cache; scp < scl; scp++) { 1096 if (scp->fc_type != FSS_CACHE_VALID) 1097 continue; 1098 1099 FSS_UNLOCK(sc, s); 1100 1101 indirp = fss_bs_indir(sc, scp->fc_cluster); 1102 if (indirp != NULL) { 1103 error = fss_bs_io(sc, FSS_WRITE, sc->sc_clnext, 1104 0, FSS_CLSIZE(sc), scp->fc_data); 1105 } else 1106 error = EIO; 1107 1108 FSS_LOCK(sc, s); 1109 1110 if (error == 0) { 1111 *indirp = sc->sc_clnext++; 1112 sc->sc_indir_dirty = 1; 1113 } else 1114 fss_error(sc, "write bs error %d", error); 1115 1116 scp->fc_type = FSS_CACHE_FREE; 1117 nfreed++; 1118 wakeup(&scp->fc_type); 1119 } 1120 1121 if (nfreed) 1122 wakeup(&sc->sc_cache); 1123 1124 /* 1125 * Process I/O requests 1126 */ 1127 nio = 0; 1128 1129 if ((bp = BUFQ_GET(sc->sc_bufq)) == NULL) 1130 continue; 1131 1132 nio++; 1133 1134 if (!FSS_ISVALID(sc)) { 1135 bp->b_error = ENXIO; 1136 bp->b_flags |= B_ERROR; 1137 bp->b_resid = bp->b_bcount; 1138 biodone(bp); 1139 continue; 1140 } 1141 1142 /* 1143 * First read from the snapshotted block device. 1144 * XXX Split to only read those parts that have not 1145 * been saved to backing store? 1146 */ 1147 1148 FSS_UNLOCK(sc, s); 1149 1150 BUF_INIT(nbp); 1151 nbp->b_flags = B_READ; 1152 nbp->b_bcount = bp->b_bcount; 1153 nbp->b_bufsize = bp->b_bcount; 1154 nbp->b_error = 0; 1155 nbp->b_data = bp->b_data; 1156 nbp->b_blkno = bp->b_blkno; 1157 nbp->b_proc = bp->b_proc; 1158 nbp->b_dev = sc->sc_bdev; 1159 nbp->b_vp = NULLVP; 1160 1161 DEV_STRATEGY(nbp); 1162 1163 if (biowait(nbp) != 0) { 1164 bp->b_resid = bp->b_bcount; 1165 bp->b_error = nbp->b_error; 1166 bp->b_flags |= B_ERROR; 1167 biodone(bp); 1168 FSS_LOCK(sc, s); 1169 continue; 1170 } 1171 1172 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno)); 1173 off = FSS_CLOFF(sc, dbtob(bp->b_blkno)); 1174 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1); 1175 bp->b_resid = bp->b_bcount; 1176 addr = bp->b_data; 1177 1178 FSS_LOCK(sc, s); 1179 1180 /* 1181 * Replace those parts that have been saved to backing store. 1182 */ 1183 1184 for (c = cl; c <= ch; 1185 c++, off = 0, bp->b_resid -= len, addr += len) { 1186 len = FSS_CLSIZE(sc)-off; 1187 if (len > bp->b_resid) 1188 len = bp->b_resid; 1189 1190 if (isclr(sc->sc_copied, c)) 1191 continue; 1192 1193 FSS_UNLOCK(sc, s); 1194 1195 indirp = fss_bs_indir(sc, c); 1196 1197 FSS_LOCK(sc, s); 1198 1199 if (indirp == NULL || *indirp == 0) { 1200 /* 1201 * Not on backing store. Either in cache 1202 * or hole in the snapshotted block device. 1203 */ 1204 for (scp = sc->sc_cache; scp < scl; scp++) 1205 if (scp->fc_type == FSS_CACHE_VALID && 1206 scp->fc_cluster == c) 1207 break; 1208 if (scp < scl) 1209 memcpy(addr, scp->fc_data+off, len); 1210 else 1211 memset(addr, 0, len); 1212 continue; 1213 } 1214 /* 1215 * Read from backing store. 1216 */ 1217 1218 FSS_UNLOCK(sc, s); 1219 1220 if ((error = fss_bs_io(sc, FSS_READ, *indirp, 1221 off, len, addr)) != 0) { 1222 bp->b_resid = bp->b_bcount; 1223 bp->b_error = error; 1224 bp->b_flags |= B_ERROR; 1225 FSS_LOCK(sc, s); 1226 break; 1227 } 1228 1229 FSS_LOCK(sc, s); 1230 1231 } 1232 1233 biodone(bp); 1234 } 1235 } 1236
Indexes created Wed Nov 11 00:26:22 UTC 2026