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 1ULL 59#define WRITE_LOG_MAGIC 0x6a736677736872ULL 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) 150{ 151 struct log_writes_c *lc = bio->bi_private; 152 struct bio_vec *bvec; 153 int i; 154 155 if (bio->bi_error) { 156 unsigned long flags; 157 158 DMERR("Error writing log block, error=%d", bio->bi_error); 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; 208 209 page = alloc_page(GFP_KERNEL); 210 if (!page) { 211 DMERR("Couldn't alloc log page"); 212 bio_put(bio); 213 goto error; 214 } 215 216 ptr = kmap_atomic(page); 217 memcpy(ptr, entry, entrylen); 218 if (datalen) 219 memcpy(ptr + entrylen, data, datalen); 220 memset(ptr + entrylen + datalen, 0, 221 lc->sectorsize - entrylen - datalen); 222 kunmap_atomic(ptr); 223 224 ret = bio_add_page(bio, page, lc->sectorsize, 0); 225 if (ret != lc->sectorsize) { 226 DMERR("Couldn't add page to the log block"); 227 goto error_bio; 228 } 229 submit_bio(WRITE, bio); 230 return 0; 231error_bio: 232 bio_put(bio); 233 __free_page(page); 234error: 235 put_io_block(lc); 236 return -1; 237} 238 239static int log_one_block(struct log_writes_c *lc, 240 struct pending_block *block, sector_t sector) 241{ 242 struct bio *bio; 243 struct log_write_entry entry; 244 size_t ret; 245 int i; 246 247 entry.sector = cpu_to_le64(block->sector); 248 entry.nr_sectors = cpu_to_le64(block->nr_sectors); 249 entry.flags = cpu_to_le64(block->flags); 250 entry.data_len = cpu_to_le64(block->datalen); 251 if (write_metadata(lc, &entry, sizeof(entry), block->data, 252 block->datalen, sector)) { 253 free_pending_block(lc, block); 254 return -1; 255 } 256 257 if (!block->vec_cnt) 258 goto out; 259 sector++; 260 261 bio = bio_alloc(GFP_KERNEL, block->vec_cnt); 262 if (!bio) { 263 DMERR("Couldn't alloc log bio"); 264 goto error; 265 } 266 atomic_inc(&lc->io_blocks); 267 bio->bi_iter.bi_size = 0; 268 bio->bi_iter.bi_sector = sector; 269 bio->bi_bdev = lc->logdev->bdev; 270 bio->bi_end_io = log_end_io; 271 bio->bi_private = lc; 272 273 for (i = 0; i < block->vec_cnt; i++) { 274 /* 275 * The page offset is always 0 because we allocate a new page 276 * for every bvec in the original bio for simplicity sake. 277 */ 278 ret = bio_add_page(bio, block->vecs[i].bv_page, 279 block->vecs[i].bv_len, 0); 280 if (ret != block->vecs[i].bv_len) { 281 atomic_inc(&lc->io_blocks); 282 submit_bio(WRITE, bio); 283 bio = bio_alloc(GFP_KERNEL, block->vec_cnt - i); 284 if (!bio) { 285 DMERR("Couldn't alloc log bio"); 286 goto error; 287 } 288 bio->bi_iter.bi_size = 0; 289 bio->bi_iter.bi_sector = sector; 290 bio->bi_bdev = lc->logdev->bdev; 291 bio->bi_end_io = log_end_io; 292 bio->bi_private = lc; 293 294 ret = bio_add_page(bio, block->vecs[i].bv_page, 295 block->vecs[i].bv_len, 0); 296 if (ret != block->vecs[i].bv_len) { 297 DMERR("Couldn't add page on new bio?"); 298 bio_put(bio); 299 goto error; 300 } 301 } 302 sector += block->vecs[i].bv_len >> SECTOR_SHIFT; 303 } 304 submit_bio(WRITE, bio); 305out: 306 kfree(block->data); 307 kfree(block); 308 put_pending_block(lc); 309 return 0; 310error: 311 free_pending_block(lc, block); 312 put_io_block(lc); 313 return -1; 314} 315 316static int log_super(struct log_writes_c *lc) 317{ 318 struct log_write_super super; 319 320 super.magic = cpu_to_le64(WRITE_LOG_MAGIC); 321 super.version = cpu_to_le64(WRITE_LOG_VERSION); 322 super.nr_entries = cpu_to_le64(lc->logged_entries); 323 super.sectorsize = cpu_to_le32(lc->sectorsize); 324 325 if (write_metadata(lc, &super, sizeof(super), NULL, 0, 0)) { 326 DMERR("Couldn't write super"); 327 return -1; 328 } 329 330 return 0; 331} 332 333static inline sector_t logdev_last_sector(struct log_writes_c *lc) 334{ 335 return i_size_read(lc->logdev->bdev->bd_inode) >> SECTOR_SHIFT; 336} 337 338static int log_writes_kthread(void *arg) 339{ 340 struct log_writes_c *lc = (struct log_writes_c *)arg; 341 sector_t sector = 0; 342 343 while (!kthread_should_stop()) { 344 bool super = false; 345 bool logging_enabled; 346 struct pending_block *block = NULL; 347 int ret; 348 349 spin_lock_irq(&lc->blocks_lock); 350 if (!list_empty(&lc->logging_blocks)) { 351 block = list_first_entry(&lc->logging_blocks, 352 struct pending_block, list); 353 list_del_init(&block->list); 354 if (!lc->logging_enabled) 355 goto next; 356 357 sector = lc->next_sector; 358 if (block->flags & LOG_DISCARD_FLAG) 359 lc->next_sector++; 360 else 361 lc->next_sector += block->nr_sectors + 1; 362 363 /* 364 * Apparently the size of the device may not be known 365 * right away, so handle this properly. 366 */ 367 if (!lc->end_sector) 368 lc->end_sector = logdev_last_sector(lc); 369 if (lc->end_sector && 370 lc->next_sector >= lc->end_sector) { 371 DMERR("Ran out of space on the logdev"); 372 lc->logging_enabled = false; 373 goto next; 374 } 375 lc->logged_entries++; 376 atomic_inc(&lc->io_blocks); 377 378 super = (block->flags & (LOG_FUA_FLAG | LOG_MARK_FLAG)); 379 if (super) 380 atomic_inc(&lc->io_blocks); 381 } 382next: 383 logging_enabled = lc->logging_enabled; 384 spin_unlock_irq(&lc->blocks_lock); 385 if (block) { 386 if (logging_enabled) { 387 ret = log_one_block(lc, block, sector); 388 if (!ret && super) 389 ret = log_super(lc); 390 if (ret) { 391 spin_lock_irq(&lc->blocks_lock); 392 lc->logging_enabled = false; 393 spin_unlock_irq(&lc->blocks_lock); 394 } 395 } else 396 free_pending_block(lc, block); 397 continue; 398 } 399 400 if (!try_to_freeze()) { 401 set_current_state(TASK_INTERRUPTIBLE); 402 if (!kthread_should_stop() && 403 !atomic_read(&lc->pending_blocks)) 404 schedule(); 405 __set_current_state(TASK_RUNNING); 406 } 407 } 408 return 0; 409} 410 411/* 412 * Construct a log-writes mapping: 413 * log-writes <dev_path> <log_dev_path> 414 */ 415static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv) 416{ 417 struct log_writes_c *lc; 418 struct dm_arg_set as; 419 const char *devname, *logdevname; 420 int ret; 421 422 as.argc = argc; 423 as.argv = argv; 424 425 if (argc < 2) { 426 ti->error = "Invalid argument count"; 427 return -EINVAL; 428 } 429 430 lc = kzalloc(sizeof(struct log_writes_c), GFP_KERNEL); 431 if (!lc) { 432 ti->error = "Cannot allocate context"; 433 return -ENOMEM; 434 } 435 spin_lock_init(&lc->blocks_lock); 436 INIT_LIST_HEAD(&lc->unflushed_blocks); 437 INIT_LIST_HEAD(&lc->logging_blocks); 438 init_waitqueue_head(&lc->wait); 439 lc->sectorsize = 1 << SECTOR_SHIFT; 440 atomic_set(&lc->io_blocks, 0); 441 atomic_set(&lc->pending_blocks, 0); 442 443 devname = dm_shift_arg(&as); 444 ret = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &lc->dev); 445 if (ret) { 446 ti->error = "Device lookup failed"; 447 goto bad; 448 } 449 450 logdevname = dm_shift_arg(&as); 451 ret = dm_get_device(ti, logdevname, dm_table_get_mode(ti->table), 452 &lc->logdev); 453 if (ret) { 454 ti->error = "Log device lookup failed"; 455 dm_put_device(ti, lc->dev); 456 goto bad; 457 } 458 459 ret = -EINVAL; 460 lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write"); 461 if (!lc->log_kthread) { 462 ti->error = "Couldn't alloc kthread"; 463 dm_put_device(ti, lc->dev); 464 dm_put_device(ti, lc->logdev); 465 goto bad; 466 } 467 468 /* We put the super at sector 0, start logging at sector 1 */ 469 lc->next_sector = 1; 470 lc->logging_enabled = true; 471 lc->end_sector = logdev_last_sector(lc); 472 lc->device_supports_discard = true; 473 474 ti->num_flush_bios = 1; 475 ti->flush_supported = true; 476 ti->num_discard_bios = 1; 477 ti->discards_supported = true; 478 ti->per_bio_data_size = sizeof(struct per_bio_data); 479 ti->private = lc; 480 return 0; 481 482bad: 483 kfree(lc); 484 return ret; 485} 486 487static int log_mark(struct log_writes_c *lc, char *data) 488{ 489 struct pending_block *block; 490 size_t maxsize = lc->sectorsize - sizeof(struct log_write_entry); 491 492 block = kzalloc(sizeof(struct pending_block), GFP_KERNEL); 493 if (!block) { 494 DMERR("Error allocating pending block"); 495 return -ENOMEM; 496 } 497 498 block->data = kstrndup(data, maxsize, GFP_KERNEL); 499 if (!block->data) { 500 DMERR("Error copying mark data"); 501 kfree(block); 502 return -ENOMEM; 503 } 504 atomic_inc(&lc->pending_blocks); 505 block->datalen = strlen(block->data); 506 block->flags |= LOG_MARK_FLAG; 507 spin_lock_irq(&lc->blocks_lock); 508 list_add_tail(&block->list, &lc->logging_blocks); 509 spin_unlock_irq(&lc->blocks_lock); 510 wake_up_process(lc->log_kthread); 511 return 0; 512} 513 514static void log_writes_dtr(struct dm_target *ti) 515{ 516 struct log_writes_c *lc = ti->private; 517 518 spin_lock_irq(&lc->blocks_lock); 519 list_splice_init(&lc->unflushed_blocks, &lc->logging_blocks); 520 spin_unlock_irq(&lc->blocks_lock); 521 522 /* 523 * This is just nice to have since it'll update the super to include the 524 * unflushed blocks, if it fails we don't really care. 525 */ 526 log_mark(lc, "dm-log-writes-end"); 527 wake_up_process(lc->log_kthread); 528 wait_event(lc->wait, !atomic_read(&lc->io_blocks) && 529 !atomic_read(&lc->pending_blocks)); 530 kthread_stop(lc->log_kthread); 531 532 WARN_ON(!list_empty(&lc->logging_blocks)); 533 WARN_ON(!list_empty(&lc->unflushed_blocks)); 534 dm_put_device(ti, lc->dev); 535 dm_put_device(ti, lc->logdev); 536 kfree(lc); 537} 538 539static void normal_map_bio(struct dm_target *ti, struct bio *bio) 540{ 541 struct log_writes_c *lc = ti->private; 542 543 bio->bi_bdev = lc->dev->bdev; 544} 545 546static int log_writes_map(struct dm_target *ti, struct bio *bio) 547{ 548 struct log_writes_c *lc = ti->private; 549 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); 550 struct pending_block *block; 551 struct bvec_iter iter; 552 struct bio_vec bv; 553 size_t alloc_size; 554 int i = 0; 555 bool flush_bio = (bio->bi_rw & REQ_FLUSH); 556 bool fua_bio = (bio->bi_rw & REQ_FUA); 557 bool discard_bio = (bio->bi_rw & REQ_DISCARD); 558 559 pb->block = NULL; 560 561 /* Don't bother doing anything if logging has been disabled */ 562 if (!lc->logging_enabled) 563 goto map_bio; 564 565 /* 566 * Map reads as normal. 567 */ 568 if (bio_data_dir(bio) == READ) 569 goto map_bio; 570 571 /* No sectors and not a flush? Don't care */ 572 if (!bio_sectors(bio) && !flush_bio) 573 goto map_bio; 574 575 /* 576 * Discards will have bi_size set but there's no actual data, so just 577 * allocate the size of the pending block. 578 */ 579 if (discard_bio) 580 alloc_size = sizeof(struct pending_block); 581 else 582 alloc_size = sizeof(struct pending_block) + sizeof(struct bio_vec) * bio_segments(bio); 583 584 block = kzalloc(alloc_size, GFP_NOIO); 585 if (!block) { 586 DMERR("Error allocating pending block"); 587 spin_lock_irq(&lc->blocks_lock); 588 lc->logging_enabled = false; 589 spin_unlock_irq(&lc->blocks_lock); 590 return -ENOMEM; 591 } 592 INIT_LIST_HEAD(&block->list); 593 pb->block = block; 594 atomic_inc(&lc->pending_blocks); 595 596 if (flush_bio) 597 block->flags |= LOG_FLUSH_FLAG; 598 if (fua_bio) 599 block->flags |= LOG_FUA_FLAG; 600 if (discard_bio) 601 block->flags |= LOG_DISCARD_FLAG; 602 603 block->sector = bio->bi_iter.bi_sector; 604 block->nr_sectors = bio_sectors(bio); 605 606 /* We don't need the data, just submit */ 607 if (discard_bio) { 608 WARN_ON(flush_bio || fua_bio); 609 if (lc->device_supports_discard) 610 goto map_bio; 611 bio_endio(bio); 612 return DM_MAPIO_SUBMITTED; 613 } 614 615 /* Flush bio, splice the unflushed blocks onto this list and submit */ 616 if (flush_bio && !bio_sectors(bio)) { 617 spin_lock_irq(&lc->blocks_lock); 618 list_splice_init(&lc->unflushed_blocks, &block->list); 619 spin_unlock_irq(&lc->blocks_lock); 620 goto map_bio; 621 } 622 623 /* 624 * We will write this bio somewhere else way later so we need to copy 625 * the actual contents into new pages so we know the data will always be 626 * there. 627 * 628 * We do this because this could be a bio from O_DIRECT in which case we 629 * can't just hold onto the page until some later point, we have to 630 * manually copy the contents. 631 */ 632 bio_for_each_segment(bv, bio, iter) { 633 struct page *page; 634 void *src, *dst; 635 636 page = alloc_page(GFP_NOIO); 637 if (!page) { 638 DMERR("Error allocing page"); 639 free_pending_block(lc, block); 640 spin_lock_irq(&lc->blocks_lock); 641 lc->logging_enabled = false; 642 spin_unlock_irq(&lc->blocks_lock); 643 return -ENOMEM; 644 } 645 646 src = kmap_atomic(bv.bv_page); 647 dst = kmap_atomic(page); 648 memcpy(dst, src + bv.bv_offset, bv.bv_len); 649 kunmap_atomic(dst); 650 kunmap_atomic(src); 651 block->vecs[i].bv_page = page; 652 block->vecs[i].bv_len = bv.bv_len; 653 block->vec_cnt++; 654 i++; 655 } 656 657 /* Had a flush with data in it, weird */ 658 if (flush_bio) { 659 spin_lock_irq(&lc->blocks_lock); 660 list_splice_init(&lc->unflushed_blocks, &block->list); 661 spin_unlock_irq(&lc->blocks_lock); 662 } 663map_bio: 664 normal_map_bio(ti, bio); 665 return DM_MAPIO_REMAPPED; 666} 667 668static int normal_end_io(struct dm_target *ti, struct bio *bio, int error) 669{ 670 struct log_writes_c *lc = ti->private; 671 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); 672 673 if (bio_data_dir(bio) == WRITE && pb->block) { 674 struct pending_block *block = pb->block; 675 unsigned long flags; 676 677 spin_lock_irqsave(&lc->blocks_lock, flags); 678 if (block->flags & LOG_FLUSH_FLAG) { 679 list_splice_tail_init(&block->list, &lc->logging_blocks); 680 list_add_tail(&block->list, &lc->logging_blocks); 681 wake_up_process(lc->log_kthread); 682 } else if (block->flags & LOG_FUA_FLAG) { 683 list_add_tail(&block->list, &lc->logging_blocks); 684 wake_up_process(lc->log_kthread); 685 } else 686 list_add_tail(&block->list, &lc->unflushed_blocks); 687 spin_unlock_irqrestore(&lc->blocks_lock, flags); 688 } 689 690 return error; 691} 692 693/* 694 * INFO format: <logged entries> <highest allocated sector> 695 */ 696static void log_writes_status(struct dm_target *ti, status_type_t type, 697 unsigned status_flags, char *result, 698 unsigned maxlen) 699{ 700 unsigned sz = 0; 701 struct log_writes_c *lc = ti->private; 702 703 switch (type) { 704 case STATUSTYPE_INFO: 705 DMEMIT("%llu %llu", lc->logged_entries, 706 (unsigned long long)lc->next_sector - 1); 707 if (!lc->logging_enabled) 708 DMEMIT(" logging_disabled"); 709 break; 710 711 case STATUSTYPE_TABLE: 712 DMEMIT("%s %s", lc->dev->name, lc->logdev->name); 713 break; 714 } 715} 716 717static int log_writes_prepare_ioctl(struct dm_target *ti, 718 struct block_device **bdev, fmode_t *mode) 719{ 720 struct log_writes_c *lc = ti->private; 721 struct dm_dev *dev = lc->dev; 722 723 *bdev = dev->bdev; 724 /* 725 * Only pass ioctls through if the device sizes match exactly. 726 */ 727 if (ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) 728 return 1; 729 return 0; 730} 731 732static int log_writes_iterate_devices(struct dm_target *ti, 733 iterate_devices_callout_fn fn, 734 void *data) 735{ 736 struct log_writes_c *lc = ti->private; 737 738 return fn(ti, lc->dev, 0, ti->len, data); 739} 740 741/* 742 * Messages supported: 743 * mark <mark data> - specify the marked data. 744 */ 745static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv) 746{ 747 int r = -EINVAL; 748 struct log_writes_c *lc = ti->private; 749 750 if (argc != 2) { 751 DMWARN("Invalid log-writes message arguments, expect 2 arguments, got %d", argc); 752 return r; 753 } 754 755 if (!strcasecmp(argv[0], "mark")) 756 r = log_mark(lc, argv[1]); 757 else 758 DMWARN("Unrecognised log writes target message received: %s", argv[0]); 759 760 return r; 761} 762 763static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits) 764{ 765 struct log_writes_c *lc = ti->private; 766 struct request_queue *q = bdev_get_queue(lc->dev->bdev); 767 768 if (!q || !blk_queue_discard(q)) { 769 lc->device_supports_discard = false; 770 limits->discard_granularity = 1 << SECTOR_SHIFT; 771 limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT); 772 } 773} 774 775static struct target_type log_writes_target = { 776 .name = "log-writes", 777 .version = {1, 0, 0}, 778 .module = THIS_MODULE, 779 .ctr = log_writes_ctr, 780 .dtr = log_writes_dtr, 781 .map = log_writes_map, 782 .end_io = normal_end_io, 783 .status = log_writes_status, 784 .prepare_ioctl = log_writes_prepare_ioctl, 785 .message = log_writes_message, 786 .iterate_devices = log_writes_iterate_devices, 787 .io_hints = log_writes_io_hints, 788}; 789 790static int __init dm_log_writes_init(void) 791{ 792 int r = dm_register_target(&log_writes_target); 793 794 if (r < 0) 795 DMERR("register failed %d", r); 796 797 return r; 798} 799 800static void __exit dm_log_writes_exit(void) 801{ 802 dm_unregister_target(&log_writes_target); 803} 804 805module_init(dm_log_writes_init); 806module_exit(dm_log_writes_exit); 807 808MODULE_DESCRIPTION(DM_NAME " log writes target"); 809MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>"); 810MODULE_LICENSE("GPL"); 811