1/* 2 * Copyright (C) 2014 Facebook. All rights reserved. 3 * 4 * This file is released under the GPL. 5 */ 6 7#include <linux/device-mapper.h> 8 9#include <linux/module.h> 10#include <linux/init.h> 11#include <linux/blkdev.h> 12#include <linux/bio.h> 13#include <linux/slab.h> 14#include <linux/kthread.h> 15#include <linux/freezer.h> 16 17#define DM_MSG_PREFIX "log-writes" 18 19/* 20 * This target will sequentially log all writes to the target device onto the 21 * log device. This is helpful for replaying writes to check for fs consistency 22 * at all times. This target provides a mechanism to mark specific events to 23 * check data at a later time. So for example you would: 24 * 25 * write data 26 * fsync 27 * dmsetup message /dev/whatever mark mymark 28 * unmount /mnt/test 29 * 30 * Then replay the log up to mymark and check the contents of the replay to 31 * verify it matches what was written. 32 * 33 * We log writes only after they have been flushed, this makes the log describe 34 * close to the order in which the data hits the actual disk, not its cache. So 35 * for example the following sequence (W means write, C means complete) 36 * 37 * Wa,Wb,Wc,Cc,Ca,FLUSH,FUAd,Cb,CFLUSH,CFUAd 38 * 39 * Would result in the log looking like this: 40 * 41 * c,a,flush,fuad,b,<other writes>,<next flush> 42 * 43 * This is meant to help expose problems where file systems do not properly wait 44 * on data being written before invoking a FLUSH. FUA bypasses cache so once it 45 * completes it is added to the log as it should be on disk. 46 * 47 * We treat DISCARDs as if they don't bypass cache so that they are logged in 48 * order of completion along with the normal writes. If we didn't do it this 49 * way we would process all the discards first and then write all the data, when 50 * in fact we want to do the data and the discard in the order that they 51 * completed. 52 */ 53#define LOG_FLUSH_FLAG (1 << 0) 54#define LOG_FUA_FLAG (1 << 1) 55#define LOG_DISCARD_FLAG (1 << 2) 56#define LOG_MARK_FLAG (1 << 3) 57 58#define WRITE_LOG_VERSION 1 59#define WRITE_LOG_MAGIC 0x6a736677736872 60 61/* 62 * The disk format for this is braindead simple. 63 * 64 * At byte 0 we have our super, followed by the following sequence for 65 * nr_entries: 66 * 67 * [ 1 sector ][ entry->nr_sectors ] 68 * [log_write_entry][ data written ] 69 * 70 * The log_write_entry takes up a full sector so we can have arbitrary length 71 * marks and it leaves us room for extra content in the future. 72 */ 73 74/* 75 * Basic info about the log for userspace. 76 */ 77struct log_write_super { 78 __le64 magic; 79 __le64 version; 80 __le64 nr_entries; 81 __le32 sectorsize; 82}; 83 84/* 85 * sector - the sector we wrote. 86 * nr_sectors - the number of sectors we wrote. 87 * flags - flags for this log entry. 88 * data_len - the size of the data in this log entry, this is for private log 89 * entry stuff, the MARK data provided by userspace for example. 90 */ 91struct log_write_entry { 92 __le64 sector; 93 __le64 nr_sectors; 94 __le64 flags; 95 __le64 data_len; 96}; 97 98struct log_writes_c { 99 struct dm_dev *dev; 100 struct dm_dev *logdev; 101 u64 logged_entries; 102 u32 sectorsize; 103 atomic_t io_blocks; 104 atomic_t pending_blocks; 105 sector_t next_sector; 106 sector_t end_sector; 107 bool logging_enabled; 108 bool device_supports_discard; 109 spinlock_t blocks_lock; 110 struct list_head unflushed_blocks; 111 struct list_head logging_blocks; 112 wait_queue_head_t wait; 113 struct task_struct *log_kthread; 114}; 115 116struct pending_block { 117 int vec_cnt; 118 u64 flags; 119 sector_t sector; 120 sector_t nr_sectors; 121 char *data; 122 u32 datalen; 123 struct list_head list; 124 struct bio_vec vecs[0]; 125}; 126 127struct per_bio_data { 128 struct pending_block *block; 129}; 130 131static void put_pending_block(struct log_writes_c *lc) 132{ 133 if (atomic_dec_and_test(&lc->pending_blocks)) { 134 smp_mb__after_atomic(); 135 if (waitqueue_active(&lc->wait)) 136 wake_up(&lc->wait); 137 } 138} 139 140static void put_io_block(struct log_writes_c *lc) 141{ 142 if (atomic_dec_and_test(&lc->io_blocks)) { 143 smp_mb__after_atomic(); 144 if (waitqueue_active(&lc->wait)) 145 wake_up(&lc->wait); 146 } 147} 148 149static void log_end_io(struct bio *bio, int err) 150{ 151 struct log_writes_c *lc = bio->bi_private; 152 struct bio_vec *bvec; 153 int i; 154 155 if (err) { 156 unsigned long flags; 157 158 DMERR("Error writing log block, error=%d", err); 159 spin_lock_irqsave(&lc->blocks_lock, flags); 160 lc->logging_enabled = false; 161 spin_unlock_irqrestore(&lc->blocks_lock, flags); 162 } 163 164 bio_for_each_segment_all(bvec, bio, i) 165 __free_page(bvec->bv_page); 166 167 put_io_block(lc); 168 bio_put(bio); 169} 170 171/* 172 * Meant to be called if there is an error, it will free all the pages 173 * associated with the block. 174 */ 175static void free_pending_block(struct log_writes_c *lc, 176 struct pending_block *block) 177{ 178 int i; 179 180 for (i = 0; i < block->vec_cnt; i++) { 181 if (block->vecs[i].bv_page) 182 __free_page(block->vecs[i].bv_page); 183 } 184 kfree(block->data); 185 kfree(block); 186 put_pending_block(lc); 187} 188 189static int write_metadata(struct log_writes_c *lc, void *entry, 190 size_t entrylen, void *data, size_t datalen, 191 sector_t sector) 192{ 193 struct bio *bio; 194 struct page *page; 195 void *ptr; 196 size_t ret; 197 198 bio = bio_alloc(GFP_KERNEL, 1); 199 if (!bio) { 200 DMERR("Couldn't alloc log bio"); 201 goto error; 202 } 203 bio->bi_iter.bi_size = 0; 204 bio->bi_iter.bi_sector = sector; 205 bio->bi_bdev = lc->logdev->bdev; 206 bio->bi_end_io = log_end_io; 207 bio->bi_private = lc; 208 set_bit(BIO_UPTODATE, &bio->bi_flags); 209 210 page = alloc_page(GFP_KERNEL); 211 if (!page) { 212 DMERR("Couldn't alloc log page"); 213 bio_put(bio); 214 goto error; 215 } 216 217 ptr = kmap_atomic(page); 218 memcpy(ptr, entry, entrylen); 219 if (datalen) 220 memcpy(ptr + entrylen, data, datalen); 221 memset(ptr + entrylen + datalen, 0, 222 lc->sectorsize - entrylen - datalen); 223 kunmap_atomic(ptr); 224 225 ret = bio_add_page(bio, page, lc->sectorsize, 0); 226 if (ret != lc->sectorsize) { 227 DMERR("Couldn't add page to the log block"); 228 goto error_bio; 229 } 230 submit_bio(WRITE, bio); 231 return 0; 232error_bio: 233 bio_put(bio); 234 __free_page(page); 235error: 236 put_io_block(lc); 237 return -1; 238} 239 240static int log_one_block(struct log_writes_c *lc, 241 struct pending_block *block, sector_t sector) 242{ 243 struct bio *bio; 244 struct log_write_entry entry; 245 size_t ret; 246 int i; 247 248 entry.sector = cpu_to_le64(block->sector); 249 entry.nr_sectors = cpu_to_le64(block->nr_sectors); 250 entry.flags = cpu_to_le64(block->flags); 251 entry.data_len = cpu_to_le64(block->datalen); 252 if (write_metadata(lc, &entry, sizeof(entry), block->data, 253 block->datalen, sector)) { 254 free_pending_block(lc, block); 255 return -1; 256 } 257 258 if (!block->vec_cnt) 259 goto out; 260 sector++; 261 262 bio = bio_alloc(GFP_KERNEL, block->vec_cnt); 263 if (!bio) { 264 DMERR("Couldn't alloc log bio"); 265 goto error; 266 } 267 atomic_inc(&lc->io_blocks); 268 bio->bi_iter.bi_size = 0; 269 bio->bi_iter.bi_sector = sector; 270 bio->bi_bdev = lc->logdev->bdev; 271 bio->bi_end_io = log_end_io; 272 bio->bi_private = lc; 273 set_bit(BIO_UPTODATE, &bio->bi_flags); 274 275 for (i = 0; i < block->vec_cnt; i++) { 276 /* 277 * The page offset is always 0 because we allocate a new page 278 * for every bvec in the original bio for simplicity sake. 279 */ 280 ret = bio_add_page(bio, block->vecs[i].bv_page, 281 block->vecs[i].bv_len, 0); 282 if (ret != block->vecs[i].bv_len) { 283 atomic_inc(&lc->io_blocks); 284 submit_bio(WRITE, bio); 285 bio = bio_alloc(GFP_KERNEL, block->vec_cnt - i); 286 if (!bio) { 287 DMERR("Couldn't alloc log bio"); 288 goto error; 289 } 290 bio->bi_iter.bi_size = 0; 291 bio->bi_iter.bi_sector = sector; 292 bio->bi_bdev = lc->logdev->bdev; 293 bio->bi_end_io = log_end_io; 294 bio->bi_private = lc; 295 set_bit(BIO_UPTODATE, &bio->bi_flags); 296 297 ret = bio_add_page(bio, block->vecs[i].bv_page, 298 block->vecs[i].bv_len, 0); 299 if (ret != block->vecs[i].bv_len) { 300 DMERR("Couldn't add page on new bio?"); 301 bio_put(bio); 302 goto error; 303 } 304 } 305 sector += block->vecs[i].bv_len >> SECTOR_SHIFT; 306 } 307 submit_bio(WRITE, bio); 308out: 309 kfree(block->data); 310 kfree(block); 311 put_pending_block(lc); 312 return 0; 313error: 314 free_pending_block(lc, block); 315 put_io_block(lc); 316 return -1; 317} 318 319static int log_super(struct log_writes_c *lc) 320{ 321 struct log_write_super super; 322 323 super.magic = cpu_to_le64(WRITE_LOG_MAGIC); 324 super.version = cpu_to_le64(WRITE_LOG_VERSION); 325 super.nr_entries = cpu_to_le64(lc->logged_entries); 326 super.sectorsize = cpu_to_le32(lc->sectorsize); 327 328 if (write_metadata(lc, &super, sizeof(super), NULL, 0, 0)) { 329 DMERR("Couldn't write super"); 330 return -1; 331 } 332 333 return 0; 334} 335 336static inline sector_t logdev_last_sector(struct log_writes_c *lc) 337{ 338 return i_size_read(lc->logdev->bdev->bd_inode) >> SECTOR_SHIFT; 339} 340 341static int log_writes_kthread(void *arg) 342{ 343 struct log_writes_c *lc = (struct log_writes_c *)arg; 344 sector_t sector = 0; 345 346 while (!kthread_should_stop()) { 347 bool super = false; 348 bool logging_enabled; 349 struct pending_block *block = NULL; 350 int ret; 351 352 spin_lock_irq(&lc->blocks_lock); 353 if (!list_empty(&lc->logging_blocks)) { 354 block = list_first_entry(&lc->logging_blocks, 355 struct pending_block, list); 356 list_del_init(&block->list); 357 if (!lc->logging_enabled) 358 goto next; 359 360 sector = lc->next_sector; 361 if (block->flags & LOG_DISCARD_FLAG) 362 lc->next_sector++; 363 else 364 lc->next_sector += block->nr_sectors + 1; 365 366 /* 367 * Apparently the size of the device may not be known 368 * right away, so handle this properly. 369 */ 370 if (!lc->end_sector) 371 lc->end_sector = logdev_last_sector(lc); 372 if (lc->end_sector && 373 lc->next_sector >= lc->end_sector) { 374 DMERR("Ran out of space on the logdev"); 375 lc->logging_enabled = false; 376 goto next; 377 } 378 lc->logged_entries++; 379 atomic_inc(&lc->io_blocks); 380 381 super = (block->flags & (LOG_FUA_FLAG | LOG_MARK_FLAG)); 382 if (super) 383 atomic_inc(&lc->io_blocks); 384 } 385next: 386 logging_enabled = lc->logging_enabled; 387 spin_unlock_irq(&lc->blocks_lock); 388 if (block) { 389 if (logging_enabled) { 390 ret = log_one_block(lc, block, sector); 391 if (!ret && super) 392 ret = log_super(lc); 393 if (ret) { 394 spin_lock_irq(&lc->blocks_lock); 395 lc->logging_enabled = false; 396 spin_unlock_irq(&lc->blocks_lock); 397 } 398 } else 399 free_pending_block(lc, block); 400 continue; 401 } 402 403 if (!try_to_freeze()) { 404 set_current_state(TASK_INTERRUPTIBLE); 405 if (!kthread_should_stop() && 406 !atomic_read(&lc->pending_blocks)) 407 schedule(); 408 __set_current_state(TASK_RUNNING); 409 } 410 } 411 return 0; 412} 413 414/* 415 * Construct a log-writes mapping: 416 * log-writes <dev_path> <log_dev_path> 417 */ 418static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv) 419{ 420 struct log_writes_c *lc; 421 struct dm_arg_set as; 422 const char *devname, *logdevname; 423 424 as.argc = argc; 425 as.argv = argv; 426 427 if (argc < 2) { 428 ti->error = "Invalid argument count"; 429 return -EINVAL; 430 } 431 432 lc = kzalloc(sizeof(struct log_writes_c), GFP_KERNEL); 433 if (!lc) { 434 ti->error = "Cannot allocate context"; 435 return -ENOMEM; 436 } 437 spin_lock_init(&lc->blocks_lock); 438 INIT_LIST_HEAD(&lc->unflushed_blocks); 439 INIT_LIST_HEAD(&lc->logging_blocks); 440 init_waitqueue_head(&lc->wait); 441 lc->sectorsize = 1 << SECTOR_SHIFT; 442 atomic_set(&lc->io_blocks, 0); 443 atomic_set(&lc->pending_blocks, 0); 444 445 devname = dm_shift_arg(&as); 446 if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &lc->dev)) { 447 ti->error = "Device lookup failed"; 448 goto bad; 449 } 450 451 logdevname = dm_shift_arg(&as); 452 if (dm_get_device(ti, logdevname, dm_table_get_mode(ti->table), &lc->logdev)) { 453 ti->error = "Log device lookup failed"; 454 dm_put_device(ti, lc->dev); 455 goto bad; 456 } 457 458 lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write"); 459 if (!lc->log_kthread) { 460 ti->error = "Couldn't alloc kthread"; 461 dm_put_device(ti, lc->dev); 462 dm_put_device(ti, lc->logdev); 463 goto bad; 464 } 465 466 /* We put the super at sector 0, start logging at sector 1 */ 467 lc->next_sector = 1; 468 lc->logging_enabled = true; 469 lc->end_sector = logdev_last_sector(lc); 470 lc->device_supports_discard = true; 471 472 ti->num_flush_bios = 1; 473 ti->flush_supported = true; 474 ti->num_discard_bios = 1; 475 ti->discards_supported = true; 476 ti->per_bio_data_size = sizeof(struct per_bio_data); 477 ti->private = lc; 478 return 0; 479 480bad: 481 kfree(lc); 482 return -EINVAL; 483} 484 485static int log_mark(struct log_writes_c *lc, char *data) 486{ 487 struct pending_block *block; 488 size_t maxsize = lc->sectorsize - sizeof(struct log_write_entry); 489 490 block = kzalloc(sizeof(struct pending_block), GFP_KERNEL); 491 if (!block) { 492 DMERR("Error allocating pending block"); 493 return -ENOMEM; 494 } 495 496 block->data = kstrndup(data, maxsize, GFP_KERNEL); 497 if (!block->data) { 498 DMERR("Error copying mark data"); 499 kfree(block); 500 return -ENOMEM; 501 } 502 atomic_inc(&lc->pending_blocks); 503 block->datalen = strlen(block->data); 504 block->flags |= LOG_MARK_FLAG; 505 spin_lock_irq(&lc->blocks_lock); 506 list_add_tail(&block->list, &lc->logging_blocks); 507 spin_unlock_irq(&lc->blocks_lock); 508 wake_up_process(lc->log_kthread); 509 return 0; 510} 511 512static void log_writes_dtr(struct dm_target *ti) 513{ 514 struct log_writes_c *lc = ti->private; 515 516 spin_lock_irq(&lc->blocks_lock); 517 list_splice_init(&lc->unflushed_blocks, &lc->logging_blocks); 518 spin_unlock_irq(&lc->blocks_lock); 519 520 /* 521 * This is just nice to have since it'll update the super to include the 522 * unflushed blocks, if it fails we don't really care. 523 */ 524 log_mark(lc, "dm-log-writes-end"); 525 wake_up_process(lc->log_kthread); 526 wait_event(lc->wait, !atomic_read(&lc->io_blocks) && 527 !atomic_read(&lc->pending_blocks)); 528 kthread_stop(lc->log_kthread); 529 530 WARN_ON(!list_empty(&lc->logging_blocks)); 531 WARN_ON(!list_empty(&lc->unflushed_blocks)); 532 dm_put_device(ti, lc->dev); 533 dm_put_device(ti, lc->logdev); 534 kfree(lc); 535} 536 537static void normal_map_bio(struct dm_target *ti, struct bio *bio) 538{ 539 struct log_writes_c *lc = ti->private; 540 541 bio->bi_bdev = lc->dev->bdev; 542} 543 544static int log_writes_map(struct dm_target *ti, struct bio *bio) 545{ 546 struct log_writes_c *lc = ti->private; 547 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); 548 struct pending_block *block; 549 struct bvec_iter iter; 550 struct bio_vec bv; 551 size_t alloc_size; 552 int i = 0; 553 bool flush_bio = (bio->bi_rw & REQ_FLUSH); 554 bool fua_bio = (bio->bi_rw & REQ_FUA); 555 bool discard_bio = (bio->bi_rw & REQ_DISCARD); 556 557 pb->block = NULL; 558 559 /* Don't bother doing anything if logging has been disabled */ 560 if (!lc->logging_enabled) 561 goto map_bio; 562 563 /* 564 * Map reads as normal. 565 */ 566 if (bio_data_dir(bio) == READ) 567 goto map_bio; 568 569 /* No sectors and not a flush? Don't care */ 570 if (!bio_sectors(bio) && !flush_bio) 571 goto map_bio; 572 573 /* 574 * Discards will have bi_size set but there's no actual data, so just 575 * allocate the size of the pending block. 576 */ 577 if (discard_bio) 578 alloc_size = sizeof(struct pending_block); 579 else 580 alloc_size = sizeof(struct pending_block) + sizeof(struct bio_vec) * bio_segments(bio); 581 582 block = kzalloc(alloc_size, GFP_NOIO); 583 if (!block) { 584 DMERR("Error allocating pending block"); 585 spin_lock_irq(&lc->blocks_lock); 586 lc->logging_enabled = false; 587 spin_unlock_irq(&lc->blocks_lock); 588 return -ENOMEM; 589 } 590 INIT_LIST_HEAD(&block->list); 591 pb->block = block; 592 atomic_inc(&lc->pending_blocks); 593 594 if (flush_bio) 595 block->flags |= LOG_FLUSH_FLAG; 596 if (fua_bio) 597 block->flags |= LOG_FUA_FLAG; 598 if (discard_bio) 599 block->flags |= LOG_DISCARD_FLAG; 600 601 block->sector = bio->bi_iter.bi_sector; 602 block->nr_sectors = bio_sectors(bio); 603 604 /* We don't need the data, just submit */ 605 if (discard_bio) { 606 WARN_ON(flush_bio || fua_bio); 607 if (lc->device_supports_discard) 608 goto map_bio; 609 bio_endio(bio, 0); 610 return DM_MAPIO_SUBMITTED; 611 } 612 613 /* Flush bio, splice the unflushed blocks onto this list and submit */ 614 if (flush_bio && !bio_sectors(bio)) { 615 spin_lock_irq(&lc->blocks_lock); 616 list_splice_init(&lc->unflushed_blocks, &block->list); 617 spin_unlock_irq(&lc->blocks_lock); 618 goto map_bio; 619 } 620 621 /* 622 * We will write this bio somewhere else way later so we need to copy 623 * the actual contents into new pages so we know the data will always be 624 * there. 625 * 626 * We do this because this could be a bio from O_DIRECT in which case we 627 * can't just hold onto the page until some later point, we have to 628 * manually copy the contents. 629 */ 630 bio_for_each_segment(bv, bio, iter) { 631 struct page *page; 632 void *src, *dst; 633 634 page = alloc_page(GFP_NOIO); 635 if (!page) { 636 DMERR("Error allocing page"); 637 free_pending_block(lc, block); 638 spin_lock_irq(&lc->blocks_lock); 639 lc->logging_enabled = false; 640 spin_unlock_irq(&lc->blocks_lock); 641 return -ENOMEM; 642 } 643 644 src = kmap_atomic(bv.bv_page); 645 dst = kmap_atomic(page); 646 memcpy(dst, src + bv.bv_offset, bv.bv_len); 647 kunmap_atomic(dst); 648 kunmap_atomic(src); 649 block->vecs[i].bv_page = page; 650 block->vecs[i].bv_len = bv.bv_len; 651 block->vec_cnt++; 652 i++; 653 } 654 655 /* Had a flush with data in it, weird */ 656 if (flush_bio) { 657 spin_lock_irq(&lc->blocks_lock); 658 list_splice_init(&lc->unflushed_blocks, &block->list); 659 spin_unlock_irq(&lc->blocks_lock); 660 } 661map_bio: 662 normal_map_bio(ti, bio); 663 return DM_MAPIO_REMAPPED; 664} 665 666static int normal_end_io(struct dm_target *ti, struct bio *bio, int error) 667{ 668 struct log_writes_c *lc = ti->private; 669 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); 670 671 if (bio_data_dir(bio) == WRITE && pb->block) { 672 struct pending_block *block = pb->block; 673 unsigned long flags; 674 675 spin_lock_irqsave(&lc->blocks_lock, flags); 676 if (block->flags & LOG_FLUSH_FLAG) { 677 list_splice_tail_init(&block->list, &lc->logging_blocks); 678 list_add_tail(&block->list, &lc->logging_blocks); 679 wake_up_process(lc->log_kthread); 680 } else if (block->flags & LOG_FUA_FLAG) { 681 list_add_tail(&block->list, &lc->logging_blocks); 682 wake_up_process(lc->log_kthread); 683 } else 684 list_add_tail(&block->list, &lc->unflushed_blocks); 685 spin_unlock_irqrestore(&lc->blocks_lock, flags); 686 } 687 688 return error; 689} 690 691/* 692 * INFO format: <logged entries> <highest allocated sector> 693 */ 694static void log_writes_status(struct dm_target *ti, status_type_t type, 695 unsigned status_flags, char *result, 696 unsigned maxlen) 697{ 698 unsigned sz = 0; 699 struct log_writes_c *lc = ti->private; 700 701 switch (type) { 702 case STATUSTYPE_INFO: 703 DMEMIT("%llu %llu", lc->logged_entries, 704 (unsigned long long)lc->next_sector - 1); 705 if (!lc->logging_enabled) 706 DMEMIT(" logging_disabled"); 707 break; 708 709 case STATUSTYPE_TABLE: 710 DMEMIT("%s %s", lc->dev->name, lc->logdev->name); 711 break; 712 } 713} 714 715static int log_writes_ioctl(struct dm_target *ti, unsigned int cmd, 716 unsigned long arg) 717{ 718 struct log_writes_c *lc = ti->private; 719 struct dm_dev *dev = lc->dev; 720 int r = 0; 721 722 /* 723 * Only pass ioctls through if the device sizes match exactly. 724 */ 725 if (ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 726 r = scsi_verify_blk_ioctl(NULL, cmd); 727 728 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg); 729} 730 731static int log_writes_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 732 struct bio_vec *biovec, int max_size) 733{ 734 struct log_writes_c *lc = ti->private; 735 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 736 737 if (!q->merge_bvec_fn) 738 return max_size; 739 740 bvm->bi_bdev = lc->dev->bdev; 741 bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector); 742 743 return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); 744} 745 746static int log_writes_iterate_devices(struct dm_target *ti, 747 iterate_devices_callout_fn fn, 748 void *data) 749{ 750 struct log_writes_c *lc = ti->private; 751 752 return fn(ti, lc->dev, 0, ti->len, data); 753} 754 755/* 756 * Messages supported: 757 * mark <mark data> - specify the marked data. 758 */ 759static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv) 760{ 761 int r = -EINVAL; 762 struct log_writes_c *lc = ti->private; 763 764 if (argc != 2) { 765 DMWARN("Invalid log-writes message arguments, expect 2 arguments, got %d", argc); 766 return r; 767 } 768 769 if (!strcasecmp(argv[0], "mark")) 770 r = log_mark(lc, argv[1]); 771 else 772 DMWARN("Unrecognised log writes target message received: %s", argv[0]); 773 774 return r; 775} 776 777static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits) 778{ 779 struct log_writes_c *lc = ti->private; 780 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 781 782 if (!q || !blk_queue_discard(q)) { 783 lc->device_supports_discard = false; 784 limits->discard_granularity = 1 << SECTOR_SHIFT; 785 limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT); 786 } 787} 788 789static struct target_type log_writes_target = { 790 .name = "log-writes", 791 .version = {1, 0, 0}, 792 .module = THIS_MODULE, 793 .ctr = log_writes_ctr, 794 .dtr = log_writes_dtr, 795 .map = log_writes_map, 796 .end_io = normal_end_io, 797 .status = log_writes_status, 798 .ioctl = log_writes_ioctl, 799 .merge = log_writes_merge, 800 .message = log_writes_message, 801 .iterate_devices = log_writes_iterate_devices, 802 .io_hints = log_writes_io_hints, 803}; 804 805static int __init dm_log_writes_init(void) 806{ 807 int r = dm_register_target(&log_writes_target); 808 809 if (r < 0) 810 DMERR("register failed %d", r); 811 812 return r; 813} 814 815static void __exit dm_log_writes_exit(void) 816{ 817 dm_unregister_target(&log_writes_target); 818} 819 820module_init(dm_log_writes_init); 821module_exit(dm_log_writes_exit); 822 823MODULE_DESCRIPTION(DM_NAME " log writes target"); 824MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>"); 825MODULE_LICENSE("GPL"); 826