drivers/md/dm-log-writes.c

   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/dax.h>
  14 #include <linux/slab.h>
  15 #include <linux/kthread.h>
  16 #include <linux/freezer.h>
  17 #include <linux/uio.h>
  18
  19 #define DM_MSG_PREFIX "log-writes"
  20
  21 /*
  22  * This target will sequentially log all writes to the target device onto the
  23  * log device.  This is helpful for replaying writes to check for fs consistency
  24  * at all times.  This target provides a mechanism to mark specific events to
  25  * check data at a later time.  So for example you would:
  26  *
  27  * write data
  28  * fsync
  29  * dmsetup message /dev/whatever mark mymark
  30  * unmount /mnt/test
  31  *
  32  * Then replay the log up to mymark and check the contents of the replay to
  33  * verify it matches what was written.
  34  *
  35  * We log writes only after they have been flushed, this makes the log describe
  36  * close to the order in which the data hits the actual disk, not its cache.  So
  37  * for example the following sequence (W means write, C means complete)
  38  *
  39  * Wa,Wb,Wc,Cc,Ca,FLUSH,FUAd,Cb,CFLUSH,CFUAd
  40  *
  41  * Would result in the log looking like this:
  42  *
  43  * c,a,b,flush,fuad,<other writes>,<next flush>
  44  *
  45  * This is meant to help expose problems where file systems do not properly wait
  46  * on data being written before invoking a FLUSH.  FUA bypasses cache so once it
  47  * completes it is added to the log as it should be on disk.
  48  *
  49  * We treat DISCARDs as if they don't bypass cache so that they are logged in
  50  * order of completion along with the normal writes.  If we didn't do it this
  51  * way we would process all the discards first and then write all the data, when
  52  * in fact we want to do the data and the discard in the order that they
  53  * completed.
  54  */
  55 #define LOG_FLUSH_FLAG          (1 << 0)
  56 #define LOG_FUA_FLAG            (1 << 1)
  57 #define LOG_DISCARD_FLAG        (1 << 2)
  58 #define LOG_MARK_FLAG           (1 << 3)
  59 #define LOG_METADATA_FLAG       (1 << 4)
  60
  61 #define WRITE_LOG_VERSION 1ULL
  62 #define WRITE_LOG_MAGIC 0x6a736677736872ULL
  63 #define WRITE_LOG_SUPER_SECTOR 0
  64
  65 /*
  66  * The disk format for this is braindead simple.
  67  *
  68  * At byte 0 we have our super, followed by the following sequence for
  69  * nr_entries:
  70  *
  71  * [   1 sector    ][  entry->nr_sectors ]
  72  * [log_write_entry][    data written    ]
  73  *
  74  * The log_write_entry takes up a full sector so we can have arbitrary length
  75  * marks and it leaves us room for extra content in the future.
  76  */
  77
  78 /*
  79  * Basic info about the log for userspace.
  80  */
  81 struct log_write_super {
  82         __le64 magic;
  83         __le64 version;
  84         __le64 nr_entries;
  85         __le32 sectorsize;
  86 };
  87
  88 /*
  89  * sector - the sector we wrote.
  90  * nr_sectors - the number of sectors we wrote.
  91  * flags - flags for this log entry.
  92  * data_len - the size of the data in this log entry, this is for private log
  93  * entry stuff, the MARK data provided by userspace for example.
  94  */
  95 struct log_write_entry {
  96         __le64 sector;
  97         __le64 nr_sectors;
  98         __le64 flags;
  99         __le64 data_len;
 100 };
 101
 102 struct log_writes_c {
 103         struct dm_dev *dev;
 104         struct dm_dev *logdev;
 105         u64 logged_entries;
 106         u32 sectorsize;
 107         u32 sectorshift;
 108         atomic_t io_blocks;
 109         atomic_t pending_blocks;
 110         sector_t next_sector;
 111         sector_t end_sector;
 112         bool logging_enabled;
 113         bool device_supports_discard;
 114         spinlock_t blocks_lock;
 115         struct list_head unflushed_blocks;
 116         struct list_head logging_blocks;
 117         wait_queue_head_t wait;
 118         struct task_struct *log_kthread;
 119         struct completion super_done;
 120 };
 121
 122 struct pending_block {
 123         int vec_cnt;
 124         u64 flags;
 125         sector_t sector;
 126         sector_t nr_sectors;
 127         char *data;
 128         u32 datalen;
 129         struct list_head list;
 130         struct bio_vec vecs[];
 131 };
 132
 133 struct per_bio_data {
 134         struct pending_block *block;
 135 };
 136
 137 static inline sector_t bio_to_dev_sectors(struct log_writes_c *lc,
 138                                           sector_t sectors)
 139 {
 140         return sectors >> (lc->sectorshift - SECTOR_SHIFT);
 141 }
 142
 143 static inline sector_t dev_to_bio_sectors(struct log_writes_c *lc,
 144                                           sector_t sectors)
 145 {
 146         return sectors << (lc->sectorshift - SECTOR_SHIFT);
 147 }
 148
 149 static void put_pending_block(struct log_writes_c *lc)
 150 {
 151         if (atomic_dec_and_test(&lc->pending_blocks)) {
 152                 smp_mb__after_atomic();
 153                 if (waitqueue_active(&lc->wait))
 154                         wake_up(&lc->wait);
 155         }
 156 }
 157
 158 static void put_io_block(struct log_writes_c *lc)
 159 {
 160         if (atomic_dec_and_test(&lc->io_blocks)) {
 161                 smp_mb__after_atomic();
 162                 if (waitqueue_active(&lc->wait))
 163                         wake_up(&lc->wait);
 164         }
 165 }
 166
 167 static void log_end_io(struct bio *bio)
 168 {
 169         struct log_writes_c *lc = bio->bi_private;
 170
 171         if (bio->bi_status) {
 172                 unsigned long flags;
 173
 174                 DMERR("Error writing log block, error=%d", bio->bi_status);
 175                 spin_lock_irqsave(&lc->blocks_lock, flags);
 176                 lc->logging_enabled = false;
 177                 spin_unlock_irqrestore(&lc->blocks_lock, flags);
 178         }
 179
 180         bio_free_pages(bio);
 181         put_io_block(lc);
 182         bio_put(bio);
 183 }
 184
 185 static void log_end_super(struct bio *bio)
 186 {
 187         struct log_writes_c *lc = bio->bi_private;
 188
 189         complete(&lc->super_done);
 190         log_end_io(bio);
 191 }
 192
 193 /*
 194  * Meant to be called if there is an error, it will free all the pages
 195  * associated with the block.
 196  */
 197 static void free_pending_block(struct log_writes_c *lc,
 198                                struct pending_block *block)
 199 {
 200         int i;
 201
 202         for (i = 0; i < block->vec_cnt; i++) {
 203                 if (block->vecs[i].bv_page)
 204                         __free_page(block->vecs[i].bv_page);
 205         }
 206         kfree(block->data);
 207         kfree(block);
 208         put_pending_block(lc);
 209 }
 210
 211 static int write_metadata(struct log_writes_c *lc, void *entry,
 212                           size_t entrylen, void *data, size_t datalen,
 213                           sector_t sector)
 214 {
 215         struct bio *bio;
 216         struct page *page;
 217         void *ptr;
 218         size_t ret;
 219
 220         bio = bio_alloc(lc->logdev->bdev, 1, REQ_OP_WRITE, GFP_KERNEL);
 221         bio->bi_iter.bi_size = 0;
 222         bio->bi_iter.bi_sector = sector;
 223         bio->bi_end_io = (sector == WRITE_LOG_SUPER_SECTOR) ?
 224                           log_end_super : log_end_io;
 225         bio->bi_private = lc;
 226
 227         page = alloc_page(GFP_KERNEL);
 228         if (!page) {
 229                 DMERR("Couldn't alloc log page");
 230                 bio_put(bio);
 231                 goto error;
 232         }
 233
 234         ptr = kmap_atomic(page);
 235         memcpy(ptr, entry, entrylen);
 236         if (datalen)
 237                 memcpy(ptr + entrylen, data, datalen);
 238         memset(ptr + entrylen + datalen, 0,
 239                lc->sectorsize - entrylen - datalen);
 240         kunmap_atomic(ptr);
 241
 242         ret = bio_add_page(bio, page, lc->sectorsize, 0);
 243         if (ret != lc->sectorsize) {
 244                 DMERR("Couldn't add page to the log block");
 245                 goto error_bio;
 246         }
 247         submit_bio(bio);
 248         return 0;
 249 error_bio:
 250         bio_put(bio);
 251         __free_page(page);
 252 error:
 253         put_io_block(lc);
 254         return -1;
 255 }
 256
 257 static int write_inline_data(struct log_writes_c *lc, void *entry,
 258                              size_t entrylen, void *data, size_t datalen,
 259                              sector_t sector)
 260 {
 261         int bio_pages, pg_datalen, pg_sectorlen, i;
 262         struct page *page;
 263         struct bio *bio;
 264         size_t ret;
 265         void *ptr;
 266
 267         while (datalen) {
 268                 bio_pages = bio_max_segs(DIV_ROUND_UP(datalen, PAGE_SIZE));
 269
 270                 atomic_inc(&lc->io_blocks);
 271
 272                 bio = bio_alloc(lc->logdev->bdev, bio_pages, REQ_OP_WRITE,
 273                                 GFP_KERNEL);
 274                 bio->bi_iter.bi_size = 0;
 275                 bio->bi_iter.bi_sector = sector;
 276                 bio->bi_end_io = log_end_io;
 277                 bio->bi_private = lc;
 278
 279                 for (i = 0; i < bio_pages; i++) {
 280                         pg_datalen = min_t(int, datalen, PAGE_SIZE);
 281                         pg_sectorlen = ALIGN(pg_datalen, lc->sectorsize);
 282
 283                         page = alloc_page(GFP_KERNEL);
 284                         if (!page) {
 285                                 DMERR("Couldn't alloc inline data page");
 286                                 goto error_bio;
 287                         }
 288
 289                         ptr = kmap_atomic(page);
 290                         memcpy(ptr, data, pg_datalen);
 291                         if (pg_sectorlen > pg_datalen)
 292                                 memset(ptr + pg_datalen, 0, pg_sectorlen - pg_datalen);
 293                         kunmap_atomic(ptr);
 294
 295                         ret = bio_add_page(bio, page, pg_sectorlen, 0);
 296                         if (ret != pg_sectorlen) {
 297                                 DMERR("Couldn't add page of inline data");
 298                                 __free_page(page);
 299                                 goto error_bio;
 300                         }
 301
 302                         datalen -= pg_datalen;
 303                         data    += pg_datalen;
 304                 }
 305                 submit_bio(bio);
 306
 307                 sector += bio_pages * PAGE_SECTORS;
 308         }
 309         return 0;
 310 error_bio:
 311         bio_free_pages(bio);
 312         bio_put(bio);
 313         put_io_block(lc);
 314         return -1;
 315 }
 316
 317 static int log_one_block(struct log_writes_c *lc,
 318                          struct pending_block *block, sector_t sector)
 319 {
 320         struct bio *bio;
 321         struct log_write_entry entry;
 322         size_t metadatalen, ret;
 323         int i;
 324
 325         entry.sector = cpu_to_le64(block->sector);
 326         entry.nr_sectors = cpu_to_le64(block->nr_sectors);
 327         entry.flags = cpu_to_le64(block->flags);
 328         entry.data_len = cpu_to_le64(block->datalen);
 329
 330         metadatalen = (block->flags & LOG_MARK_FLAG) ? block->datalen : 0;
 331         if (write_metadata(lc, &entry, sizeof(entry), block->data,
 332                            metadatalen, sector)) {
 333                 free_pending_block(lc, block);
 334                 return -1;
 335         }
 336
 337         sector += dev_to_bio_sectors(lc, 1);
 338
 339         if (block->datalen && metadatalen == 0) {
 340                 if (write_inline_data(lc, &entry, sizeof(entry), block->data,
 341                                       block->datalen, sector)) {
 342                         free_pending_block(lc, block);
 343                         return -1;
 344                 }
 345                 /* we don't support both inline data & bio data */
 346                 goto out;
 347         }
 348
 349         if (!block->vec_cnt)
 350                 goto out;
 351
 352         atomic_inc(&lc->io_blocks);
 353         bio = bio_alloc(lc->logdev->bdev, bio_max_segs(block->vec_cnt),
 354                         REQ_OP_WRITE, GFP_KERNEL);
 355         bio->bi_iter.bi_size = 0;
 356         bio->bi_iter.bi_sector = sector;
 357         bio->bi_end_io = log_end_io;
 358         bio->bi_private = lc;
 359
 360         for (i = 0; i < block->vec_cnt; i++) {
 361                 /*
 362                  * The page offset is always 0 because we allocate a new page
 363                  * for every bvec in the original bio for simplicity sake.
 364                  */
 365                 ret = bio_add_page(bio, block->vecs[i].bv_page,
 366                                    block->vecs[i].bv_len, 0);
 367                 if (ret != block->vecs[i].bv_len) {
 368                         atomic_inc(&lc->io_blocks);
 369                         submit_bio(bio);
 370                         bio = bio_alloc(lc->logdev->bdev,
 371                                         bio_max_segs(block->vec_cnt - i),
 372                                         REQ_OP_WRITE, GFP_KERNEL);
 373                         bio->bi_iter.bi_size = 0;
 374                         bio->bi_iter.bi_sector = sector;
 375                         bio->bi_end_io = log_end_io;
 376                         bio->bi_private = lc;
 377
 378                         ret = bio_add_page(bio, block->vecs[i].bv_page,
 379                                            block->vecs[i].bv_len, 0);
 380                         if (ret != block->vecs[i].bv_len) {
 381                                 DMERR("Couldn't add page on new bio?");
 382                                 bio_put(bio);
 383                                 goto error;
 384                         }
 385                 }
 386                 sector += block->vecs[i].bv_len >> SECTOR_SHIFT;
 387         }
 388         submit_bio(bio);
 389 out:
 390         kfree(block->data);
 391         kfree(block);
 392         put_pending_block(lc);
 393         return 0;
 394 error:
 395         free_pending_block(lc, block);
 396         put_io_block(lc);
 397         return -1;
 398 }
 399
 400 static int log_super(struct log_writes_c *lc)
 401 {
 402         struct log_write_super super;
 403
 404         super.magic = cpu_to_le64(WRITE_LOG_MAGIC);
 405         super.version = cpu_to_le64(WRITE_LOG_VERSION);
 406         super.nr_entries = cpu_to_le64(lc->logged_entries);
 407         super.sectorsize = cpu_to_le32(lc->sectorsize);
 408
 409         if (write_metadata(lc, &super, sizeof(super), NULL, 0,
 410                            WRITE_LOG_SUPER_SECTOR)) {
 411                 DMERR("Couldn't write super");
 412                 return -1;
 413         }
 414
 415         /*
 416          * Super sector should be writen in-order, otherwise the
 417          * nr_entries could be rewritten incorrectly by an old bio.
 418          */
 419         wait_for_completion_io(&lc->super_done);
 420
 421         return 0;
 422 }
 423
 424 static inline sector_t logdev_last_sector(struct log_writes_c *lc)
 425 {
 426         return bdev_nr_sectors(lc->logdev->bdev);
 427 }
 428
 429 static int log_writes_kthread(void *arg)
 430 {
 431         struct log_writes_c *lc = (struct log_writes_c *)arg;
 432         sector_t sector = 0;
 433
 434         while (!kthread_should_stop()) {
 435                 bool super = false;
 436                 bool logging_enabled;
 437                 struct pending_block *block = NULL;
 438                 int ret;
 439
 440                 spin_lock_irq(&lc->blocks_lock);
 441                 if (!list_empty(&lc->logging_blocks)) {
 442                         block = list_first_entry(&lc->logging_blocks,
 443                                                  struct pending_block, list);
 444                         list_del_init(&block->list);
 445                         if (!lc->logging_enabled)
 446                                 goto next;
 447
 448                         sector = lc->next_sector;
 449                         if (!(block->flags & LOG_DISCARD_FLAG))
 450                                 lc->next_sector += dev_to_bio_sectors(lc, block->nr_sectors);
 451                         lc->next_sector += dev_to_bio_sectors(lc, 1);
 452
 453                         /*
 454                          * Apparently the size of the device may not be known
 455                          * right away, so handle this properly.
 456                          */
 457                         if (!lc->end_sector)
 458                                 lc->end_sector = logdev_last_sector(lc);
 459                         if (lc->end_sector &&
 460                             lc->next_sector >= lc->end_sector) {
 461                                 DMERR("Ran out of space on the logdev");
 462                                 lc->logging_enabled = false;
 463                                 goto next;
 464                         }
 465                         lc->logged_entries++;
 466                         atomic_inc(&lc->io_blocks);
 467
 468                         super = (block->flags & (LOG_FUA_FLAG | LOG_MARK_FLAG));
 469                         if (super)
 470                                 atomic_inc(&lc->io_blocks);
 471                 }
 472 next:
 473                 logging_enabled = lc->logging_enabled;
 474                 spin_unlock_irq(&lc->blocks_lock);
 475                 if (block) {
 476                         if (logging_enabled) {
 477                                 ret = log_one_block(lc, block, sector);
 478                                 if (!ret && super)
 479                                         ret = log_super(lc);
 480                                 if (ret) {
 481                                         spin_lock_irq(&lc->blocks_lock);
 482                                         lc->logging_enabled = false;
 483                                         spin_unlock_irq(&lc->blocks_lock);
 484                                 }
 485                         } else
 486                                 free_pending_block(lc, block);
 487                         continue;
 488                 }
 489
 490                 if (!try_to_freeze()) {
 491                         set_current_state(TASK_INTERRUPTIBLE);
 492                         if (!kthread_should_stop() &&
 493                             list_empty(&lc->logging_blocks))
 494                                 schedule();
 495                         __set_current_state(TASK_RUNNING);
 496                 }
 497         }
 498         return 0;
 499 }
 500
 501 /*
 502  * Construct a log-writes mapping:
 503  * log-writes <dev_path> <log_dev_path>
 504  */
 505 static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 506 {
 507         struct log_writes_c *lc;
 508         struct dm_arg_set as;
 509         const char *devname, *logdevname;
 510         int ret;
 511
 512         as.argc = argc;
 513         as.argv = argv;
 514
 515         if (argc < 2) {
 516                 ti->error = "Invalid argument count";
 517                 return -EINVAL;
 518         }
 519
 520         lc = kzalloc(sizeof(struct log_writes_c), GFP_KERNEL);
 521         if (!lc) {
 522                 ti->error = "Cannot allocate context";
 523                 return -ENOMEM;
 524         }
 525         spin_lock_init(&lc->blocks_lock);
 526         INIT_LIST_HEAD(&lc->unflushed_blocks);
 527         INIT_LIST_HEAD(&lc->logging_blocks);
 528         init_waitqueue_head(&lc->wait);
 529         init_completion(&lc->super_done);
 530         atomic_set(&lc->io_blocks, 0);
 531         atomic_set(&lc->pending_blocks, 0);
 532
 533         devname = dm_shift_arg(&as);
 534         ret = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &lc->dev);
 535         if (ret) {
 536                 ti->error = "Device lookup failed";
 537                 goto bad;
 538         }
 539
 540         logdevname = dm_shift_arg(&as);
 541         ret = dm_get_device(ti, logdevname, dm_table_get_mode(ti->table),
 542                             &lc->logdev);
 543         if (ret) {
 544                 ti->error = "Log device lookup failed";
 545                 dm_put_device(ti, lc->dev);
 546                 goto bad;
 547         }
 548
 549         lc->sectorsize = bdev_logical_block_size(lc->dev->bdev);
 550         lc->sectorshift = ilog2(lc->sectorsize);
 551         lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write");
 552         if (IS_ERR(lc->log_kthread)) {
 553                 ret = PTR_ERR(lc->log_kthread);
 554                 ti->error = "Couldn't alloc kthread";
 555                 dm_put_device(ti, lc->dev);
 556                 dm_put_device(ti, lc->logdev);
 557                 goto bad;
 558         }
 559
 560         /*
 561          * next_sector is in 512b sectors to correspond to what bi_sector expects.
 562          * The super starts at sector 0, and the next_sector is the next logical
 563          * one based on the sectorsize of the device.
 564          */
 565         lc->next_sector = lc->sectorsize >> SECTOR_SHIFT;
 566         lc->logging_enabled = true;
 567         lc->end_sector = logdev_last_sector(lc);
 568         lc->device_supports_discard = true;
 569
 570         ti->num_flush_bios = 1;
 571         ti->flush_supported = true;
 572         ti->num_discard_bios = 1;
 573         ti->discards_supported = true;
 574         ti->per_io_data_size = sizeof(struct per_bio_data);
 575         ti->private = lc;
 576         return 0;
 577
 578 bad:
 579         kfree(lc);
 580         return ret;
 581 }
 582
 583 static int log_mark(struct log_writes_c *lc, char *data)
 584 {
 585         struct pending_block *block;
 586         size_t maxsize = lc->sectorsize - sizeof(struct log_write_entry);
 587
 588         block = kzalloc(sizeof(struct pending_block), GFP_KERNEL);
 589         if (!block) {
 590                 DMERR("Error allocating pending block");
 591                 return -ENOMEM;
 592         }
 593
 594         block->data = kstrndup(data, maxsize - 1, GFP_KERNEL);
 595         if (!block->data) {
 596                 DMERR("Error copying mark data");
 597                 kfree(block);
 598                 return -ENOMEM;
 599         }
 600         atomic_inc(&lc->pending_blocks);
 601         block->datalen = strlen(block->data);
 602         block->flags |= LOG_MARK_FLAG;
 603         spin_lock_irq(&lc->blocks_lock);
 604         list_add_tail(&block->list, &lc->logging_blocks);
 605         spin_unlock_irq(&lc->blocks_lock);
 606         wake_up_process(lc->log_kthread);
 607         return 0;
 608 }
 609
 610 static void log_writes_dtr(struct dm_target *ti)
 611 {
 612         struct log_writes_c *lc = ti->private;
 613
 614         spin_lock_irq(&lc->blocks_lock);
 615         list_splice_init(&lc->unflushed_blocks, &lc->logging_blocks);
 616         spin_unlock_irq(&lc->blocks_lock);
 617
 618         /*
 619          * This is just nice to have since it'll update the super to include the
 620          * unflushed blocks, if it fails we don't really care.
 621          */
 622         log_mark(lc, "dm-log-writes-end");
 623         wake_up_process(lc->log_kthread);
 624         wait_event(lc->wait, !atomic_read(&lc->io_blocks) &&
 625                    !atomic_read(&lc->pending_blocks));
 626         kthread_stop(lc->log_kthread);
 627
 628         WARN_ON(!list_empty(&lc->logging_blocks));
 629         WARN_ON(!list_empty(&lc->unflushed_blocks));
 630         dm_put_device(ti, lc->dev);
 631         dm_put_device(ti, lc->logdev);
 632         kfree(lc);
 633 }
 634
 635 static void normal_map_bio(struct dm_target *ti, struct bio *bio)
 636 {
 637         struct log_writes_c *lc = ti->private;
 638
 639         bio_set_dev(bio, lc->dev->bdev);
 640 }
 641
 642 static int log_writes_map(struct dm_target *ti, struct bio *bio)
 643 {
 644         struct log_writes_c *lc = ti->private;
 645         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 646         struct pending_block *block;
 647         struct bvec_iter iter;
 648         struct bio_vec bv;
 649         size_t alloc_size;
 650         int i = 0;
 651         bool flush_bio = (bio->bi_opf & REQ_PREFLUSH);
 652         bool fua_bio = (bio->bi_opf & REQ_FUA);
 653         bool discard_bio = (bio_op(bio) == REQ_OP_DISCARD);
 654         bool meta_bio = (bio->bi_opf & REQ_META);
 655
 656         pb->block = NULL;
 657
 658         /* Don't bother doing anything if logging has been disabled */
 659         if (!lc->logging_enabled)
 660                 goto map_bio;
 661
 662         /*
 663          * Map reads as normal.
 664          */
 665         if (bio_data_dir(bio) == READ)
 666                 goto map_bio;
 667
 668         /* No sectors and not a flush?  Don't care */
 669         if (!bio_sectors(bio) && !flush_bio)
 670                 goto map_bio;
 671
 672         /*
 673          * Discards will have bi_size set but there's no actual data, so just
 674          * allocate the size of the pending block.
 675          */
 676         if (discard_bio)
 677                 alloc_size = sizeof(struct pending_block);
 678         else
 679                 alloc_size = struct_size(block, vecs, bio_segments(bio));
 680
 681         block = kzalloc(alloc_size, GFP_NOIO);
 682         if (!block) {
 683                 DMERR("Error allocating pending block");
 684                 spin_lock_irq(&lc->blocks_lock);
 685                 lc->logging_enabled = false;
 686                 spin_unlock_irq(&lc->blocks_lock);
 687                 return DM_MAPIO_KILL;
 688         }
 689         INIT_LIST_HEAD(&block->list);
 690         pb->block = block;
 691         atomic_inc(&lc->pending_blocks);
 692
 693         if (flush_bio)
 694                 block->flags |= LOG_FLUSH_FLAG;
 695         if (fua_bio)
 696                 block->flags |= LOG_FUA_FLAG;
 697         if (discard_bio)
 698                 block->flags |= LOG_DISCARD_FLAG;
 699         if (meta_bio)
 700                 block->flags |= LOG_METADATA_FLAG;
 701
 702         block->sector = bio_to_dev_sectors(lc, bio->bi_iter.bi_sector);
 703         block->nr_sectors = bio_to_dev_sectors(lc, bio_sectors(bio));
 704
 705         /* We don't need the data, just submit */
 706         if (discard_bio) {
 707                 WARN_ON(flush_bio || fua_bio);
 708                 if (lc->device_supports_discard)
 709                         goto map_bio;
 710                 bio_endio(bio);
 711                 return DM_MAPIO_SUBMITTED;
 712         }
 713
 714         /* Flush bio, splice the unflushed blocks onto this list and submit */
 715         if (flush_bio && !bio_sectors(bio)) {
 716                 spin_lock_irq(&lc->blocks_lock);
 717                 list_splice_init(&lc->unflushed_blocks, &block->list);
 718                 spin_unlock_irq(&lc->blocks_lock);
 719                 goto map_bio;
 720         }
 721
 722         /*
 723          * We will write this bio somewhere else way later so we need to copy
 724          * the actual contents into new pages so we know the data will always be
 725          * there.
 726          *
 727          * We do this because this could be a bio from O_DIRECT in which case we
 728          * can't just hold onto the page until some later point, we have to
 729          * manually copy the contents.
 730          */
 731         bio_for_each_segment(bv, bio, iter) {
 732                 struct page *page;
 733                 void *dst;
 734
 735                 page = alloc_page(GFP_NOIO);
 736                 if (!page) {
 737                         DMERR("Error allocing page");
 738                         free_pending_block(lc, block);
 739                         spin_lock_irq(&lc->blocks_lock);
 740                         lc->logging_enabled = false;
 741                         spin_unlock_irq(&lc->blocks_lock);
 742                         return DM_MAPIO_KILL;
 743                 }
 744
 745                 dst = kmap_atomic(page);
 746                 memcpy_from_bvec(dst, &bv);
 747                 kunmap_atomic(dst);
 748                 block->vecs[i].bv_page = page;
 749                 block->vecs[i].bv_len = bv.bv_len;
 750                 block->vec_cnt++;
 751                 i++;
 752         }
 753
 754         /* Had a flush with data in it, weird */
 755         if (flush_bio) {
 756                 spin_lock_irq(&lc->blocks_lock);
 757                 list_splice_init(&lc->unflushed_blocks, &block->list);
 758                 spin_unlock_irq(&lc->blocks_lock);
 759         }
 760 map_bio:
 761         normal_map_bio(ti, bio);
 762         return DM_MAPIO_REMAPPED;
 763 }
 764
 765 static int normal_end_io(struct dm_target *ti, struct bio *bio,
 766                 blk_status_t *error)
 767 {
 768         struct log_writes_c *lc = ti->private;
 769         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 770
 771         if (bio_data_dir(bio) == WRITE && pb->block) {
 772                 struct pending_block *block = pb->block;
 773                 unsigned long flags;
 774
 775                 spin_lock_irqsave(&lc->blocks_lock, flags);
 776                 if (block->flags & LOG_FLUSH_FLAG) {
 777                         list_splice_tail_init(&block->list, &lc->logging_blocks);
 778                         list_add_tail(&block->list, &lc->logging_blocks);
 779                         wake_up_process(lc->log_kthread);
 780                 } else if (block->flags & LOG_FUA_FLAG) {
 781                         list_add_tail(&block->list, &lc->logging_blocks);
 782                         wake_up_process(lc->log_kthread);
 783                 } else
 784                         list_add_tail(&block->list, &lc->unflushed_blocks);
 785                 spin_unlock_irqrestore(&lc->blocks_lock, flags);
 786         }
 787
 788         return DM_ENDIO_DONE;
 789 }
 790
 791 /*
 792  * INFO format: <logged entries> <highest allocated sector>
 793  */
 794 static void log_writes_status(struct dm_target *ti, status_type_t type,
 795                               unsigned status_flags, char *result,
 796                               unsigned maxlen)
 797 {
 798         unsigned sz = 0;
 799         struct log_writes_c *lc = ti->private;
 800
 801         switch (type) {
 802         case STATUSTYPE_INFO:
 803                 DMEMIT("%llu %llu", lc->logged_entries,
 804                        (unsigned long long)lc->next_sector - 1);
 805                 if (!lc->logging_enabled)
 806                         DMEMIT(" logging_disabled");
 807                 break;
 808
 809         case STATUSTYPE_TABLE:
 810                 DMEMIT("%s %s", lc->dev->name, lc->logdev->name);
 811                 break;
 812
 813         case STATUSTYPE_IMA:
 814                 *result = '\0';
 815                 break;
 816         }
 817 }
 818
 819 static int log_writes_prepare_ioctl(struct dm_target *ti,
 820                                     struct block_device **bdev)
 821 {
 822         struct log_writes_c *lc = ti->private;
 823         struct dm_dev *dev = lc->dev;
 824
 825         *bdev = dev->bdev;
 826         /*
 827          * Only pass ioctls through if the device sizes match exactly.
 828          */
 829         if (ti->len != bdev_nr_sectors(dev->bdev))
 830                 return 1;
 831         return 0;
 832 }
 833
 834 static int log_writes_iterate_devices(struct dm_target *ti,
 835                                       iterate_devices_callout_fn fn,
 836                                       void *data)
 837 {
 838         struct log_writes_c *lc = ti->private;
 839
 840         return fn(ti, lc->dev, 0, ti->len, data);
 841 }
 842
 843 /*
 844  * Messages supported:
 845  *   mark <mark data> - specify the marked data.
 846  */
 847 static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv,
 848                               char *result, unsigned maxlen)
 849 {
 850         int r = -EINVAL;
 851         struct log_writes_c *lc = ti->private;
 852
 853         if (argc != 2) {
 854                 DMWARN("Invalid log-writes message arguments, expect 2 arguments, got %d", argc);
 855                 return r;
 856         }
 857
 858         if (!strcasecmp(argv[0], "mark"))
 859                 r = log_mark(lc, argv[1]);
 860         else
 861                 DMWARN("Unrecognised log writes target message received: %s", argv[0]);
 862
 863         return r;
 864 }
 865
 866 static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits)
 867 {
 868         struct log_writes_c *lc = ti->private;
 869
 870         if (!bdev_max_discard_sectors(lc->dev->bdev)) {
 871                 lc->device_supports_discard = false;
 872                 limits->discard_granularity = lc->sectorsize;
 873                 limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT);
 874         }
 875         limits->logical_block_size = bdev_logical_block_size(lc->dev->bdev);
 876         limits->physical_block_size = bdev_physical_block_size(lc->dev->bdev);
 877         limits->io_min = limits->physical_block_size;
 878 }
 879
 880 #if IS_ENABLED(CONFIG_FS_DAX)
 881 static struct dax_device *log_writes_dax_pgoff(struct dm_target *ti,
 882                 pgoff_t *pgoff)
 883 {
 884         struct log_writes_c *lc = ti->private;
 885
 886         *pgoff += (get_start_sect(lc->dev->bdev) >> PAGE_SECTORS_SHIFT);
 887         return lc->dev->dax_dev;
 888 }
 889
 890 static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 891                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 892                 pfn_t *pfn)
 893 {
 894         struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 895
 896         return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
 897 }
 898
 899 static int log_writes_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
 900                                           size_t nr_pages)
 901 {
 902         struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 903
 904         return dax_zero_page_range(dax_dev, pgoff, nr_pages << PAGE_SHIFT);
 905 }
 906
 907 static size_t log_writes_dax_recovery_write(struct dm_target *ti,
 908                 pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
 909 {
 910         struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 911
 912         return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
 913 }
 914
 915 #else
 916 #define log_writes_dax_direct_access NULL
 917 #define log_writes_dax_zero_page_range NULL
 918 #define log_writes_dax_recovery_write NULL
 919 #endif
 920
 921 static struct target_type log_writes_target = {
 922         .name   = "log-writes",
 923         .version = {1, 1, 0},
 924         .module = THIS_MODULE,
 925         .ctr    = log_writes_ctr,
 926         .dtr    = log_writes_dtr,
 927         .map    = log_writes_map,
 928         .end_io = normal_end_io,
 929         .status = log_writes_status,
 930         .prepare_ioctl = log_writes_prepare_ioctl,
 931         .message = log_writes_message,
 932         .iterate_devices = log_writes_iterate_devices,
 933         .io_hints = log_writes_io_hints,
 934         .direct_access = log_writes_dax_direct_access,
 935         .dax_zero_page_range = log_writes_dax_zero_page_range,
 936         .dax_recovery_write = log_writes_dax_recovery_write,
 937 };
 938
 939 static int __init dm_log_writes_init(void)
 940 {
 941         int r = dm_register_target(&log_writes_target);
 942
 943         if (r < 0)
 944                 DMERR("register failed %d", r);
 945
 946         return r;
 947 }
 948
 949 static void __exit dm_log_writes_exit(void)
 950 {
 951         dm_unregister_target(&log_writes_target);
 952 }
 953
 954 module_init(dm_log_writes_init);
 955 module_exit(dm_log_writes_exit);
 956
 957 MODULE_DESCRIPTION(DM_NAME " log writes target");
 958 MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>");
 959 MODULE_LICENSE("GPL");