drivers/md/dm-writecache.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2018 Red Hat. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/device-mapper.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/kthread.h>
  13 #include <linux/dm-io.h>
  14 #include <linux/dm-kcopyd.h>
  15 #include <linux/dax.h>
  16 #include <linux/pfn_t.h>
  17 #include <linux/libnvdimm.h>
  18
  19 #define DM_MSG_PREFIX "writecache"
  20
  21 #define HIGH_WATERMARK                  50
  22 #define LOW_WATERMARK                   45
  23 #define MAX_WRITEBACK_JOBS              0
  24 #define ENDIO_LATENCY                   16
  25 #define WRITEBACK_LATENCY               64
  26 #define AUTOCOMMIT_BLOCKS_SSD           65536
  27 #define AUTOCOMMIT_BLOCKS_PMEM          64
  28 #define AUTOCOMMIT_MSEC                 1000
  29 #define MAX_AGE_DIV                     16
  30 #define MAX_AGE_UNSPECIFIED             -1UL
  31
  32 #define BITMAP_GRANULARITY      65536
  33 #if BITMAP_GRANULARITY < PAGE_SIZE
  34 #undef BITMAP_GRANULARITY
  35 #define BITMAP_GRANULARITY      PAGE_SIZE
  36 #endif
  37
  38 #if IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER)
  39 #define DM_WRITECACHE_HAS_PMEM
  40 #endif
  41
  42 #ifdef DM_WRITECACHE_HAS_PMEM
  43 #define pmem_assign(dest, src)                                  \
  44 do {                                                            \
  45         typeof(dest) uniq = (src);                              \
  46         memcpy_flushcache(&(dest), &uniq, sizeof(dest));        \
  47 } while (0)
  48 #else
  49 #define pmem_assign(dest, src)  ((dest) = (src))
  50 #endif
  51
  52 #if IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC) && defined(DM_WRITECACHE_HAS_PMEM)
  53 #define DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
  54 #endif
  55
  56 #define MEMORY_SUPERBLOCK_MAGIC         0x23489321
  57 #define MEMORY_SUPERBLOCK_VERSION       1
  58
  59 struct wc_memory_entry {
  60         __le64 original_sector;
  61         __le64 seq_count;
  62 };
  63
  64 struct wc_memory_superblock {
  65         union {
  66                 struct {
  67                         __le32 magic;
  68                         __le32 version;
  69                         __le32 block_size;
  70                         __le32 pad;
  71                         __le64 n_blocks;
  72                         __le64 seq_count;
  73                 };
  74                 __le64 padding[8];
  75         };
  76         struct wc_memory_entry entries[0];
  77 };
  78
  79 struct wc_entry {
  80         struct rb_node rb_node;
  81         struct list_head lru;
  82         unsigned short wc_list_contiguous;
  83         bool write_in_progress
  84 #if BITS_PER_LONG == 64
  85                 :1
  86 #endif
  87         ;
  88         unsigned long index
  89 #if BITS_PER_LONG == 64
  90                 :47
  91 #endif
  92         ;
  93         unsigned long age;
  94 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
  95         uint64_t original_sector;
  96         uint64_t seq_count;
  97 #endif
  98 };
  99
 100 #ifdef DM_WRITECACHE_HAS_PMEM
 101 #define WC_MODE_PMEM(wc)                        ((wc)->pmem_mode)
 102 #define WC_MODE_FUA(wc)                         ((wc)->writeback_fua)
 103 #else
 104 #define WC_MODE_PMEM(wc)                        false
 105 #define WC_MODE_FUA(wc)                         false
 106 #endif
 107 #define WC_MODE_SORT_FREELIST(wc)               (!WC_MODE_PMEM(wc))
 108
 109 struct dm_writecache {
 110         struct mutex lock;
 111         struct list_head lru;
 112         union {
 113                 struct list_head freelist;
 114                 struct {
 115                         struct rb_root freetree;
 116                         struct wc_entry *current_free;
 117                 };
 118         };
 119         struct rb_root tree;
 120
 121         size_t freelist_size;
 122         size_t writeback_size;
 123         size_t freelist_high_watermark;
 124         size_t freelist_low_watermark;
 125         unsigned long max_age;
 126
 127         unsigned uncommitted_blocks;
 128         unsigned autocommit_blocks;
 129         unsigned max_writeback_jobs;
 130
 131         int error;
 132
 133         unsigned long autocommit_jiffies;
 134         struct timer_list autocommit_timer;
 135         struct wait_queue_head freelist_wait;
 136
 137         struct timer_list max_age_timer;
 138
 139         atomic_t bio_in_progress[2];
 140         struct wait_queue_head bio_in_progress_wait[2];
 141
 142         struct dm_target *ti;
 143         struct dm_dev *dev;
 144         struct dm_dev *ssd_dev;
 145         sector_t start_sector;
 146         void *memory_map;
 147         uint64_t memory_map_size;
 148         size_t metadata_sectors;
 149         size_t n_blocks;
 150         uint64_t seq_count;
 151         void *block_start;
 152         struct wc_entry *entries;
 153         unsigned block_size;
 154         unsigned char block_size_bits;
 155
 156         bool pmem_mode:1;
 157         bool writeback_fua:1;
 158
 159         bool overwrote_committed:1;
 160         bool memory_vmapped:1;
 161
 162         bool high_wm_percent_set:1;
 163         bool low_wm_percent_set:1;
 164         bool max_writeback_jobs_set:1;
 165         bool autocommit_blocks_set:1;
 166         bool autocommit_time_set:1;
 167         bool writeback_fua_set:1;
 168         bool flush_on_suspend:1;
 169         bool cleaner:1;
 170
 171         unsigned writeback_all;
 172         struct workqueue_struct *writeback_wq;
 173         struct work_struct writeback_work;
 174         struct work_struct flush_work;
 175
 176         struct dm_io_client *dm_io;
 177
 178         raw_spinlock_t endio_list_lock;
 179         struct list_head endio_list;
 180         struct task_struct *endio_thread;
 181
 182         struct task_struct *flush_thread;
 183         struct bio_list flush_list;
 184
 185         struct dm_kcopyd_client *dm_kcopyd;
 186         unsigned long *dirty_bitmap;
 187         unsigned dirty_bitmap_size;
 188
 189         struct bio_set bio_set;
 190         mempool_t copy_pool;
 191 };
 192
 193 #define WB_LIST_INLINE          16
 194
 195 struct writeback_struct {
 196         struct list_head endio_entry;
 197         struct dm_writecache *wc;
 198         struct wc_entry **wc_list;
 199         unsigned wc_list_n;
 200         struct wc_entry *wc_list_inline[WB_LIST_INLINE];
 201         struct bio bio;
 202 };
 203
 204 struct copy_struct {
 205         struct list_head endio_entry;
 206         struct dm_writecache *wc;
 207         struct wc_entry *e;
 208         unsigned n_entries;
 209         int error;
 210 };
 211
 212 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(dm_writecache_throttle,
 213                                             "A percentage of time allocated for data copying");
 214
 215 static void wc_lock(struct dm_writecache *wc)
 216 {
 217         mutex_lock(&wc->lock);
 218 }
 219
 220 static void wc_unlock(struct dm_writecache *wc)
 221 {
 222         mutex_unlock(&wc->lock);
 223 }
 224
 225 #ifdef DM_WRITECACHE_HAS_PMEM
 226 static int persistent_memory_claim(struct dm_writecache *wc)
 227 {
 228         int r;
 229         loff_t s;
 230         long p, da;
 231         pfn_t pfn;
 232         int id;
 233         struct page **pages;
 234         sector_t offset;
 235
 236         wc->memory_vmapped = false;
 237
 238         s = wc->memory_map_size;
 239         p = s >> PAGE_SHIFT;
 240         if (!p) {
 241                 r = -EINVAL;
 242                 goto err1;
 243         }
 244         if (p != s >> PAGE_SHIFT) {
 245                 r = -EOVERFLOW;
 246                 goto err1;
 247         }
 248
 249         offset = get_start_sect(wc->ssd_dev->bdev);
 250         if (offset & (PAGE_SIZE / 512 - 1)) {
 251                 r = -EINVAL;
 252                 goto err1;
 253         }
 254         offset >>= PAGE_SHIFT - 9;
 255
 256         id = dax_read_lock();
 257
 258         da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, &wc->memory_map, &pfn);
 259         if (da < 0) {
 260                 wc->memory_map = NULL;
 261                 r = da;
 262                 goto err2;
 263         }
 264         if (!pfn_t_has_page(pfn)) {
 265                 wc->memory_map = NULL;
 266                 r = -EOPNOTSUPP;
 267                 goto err2;
 268         }
 269         if (da != p) {
 270                 long i;
 271                 wc->memory_map = NULL;
 272                 pages = kvmalloc_array(p, sizeof(struct page *), GFP_KERNEL);
 273                 if (!pages) {
 274                         r = -ENOMEM;
 275                         goto err2;
 276                 }
 277                 i = 0;
 278                 do {
 279                         long daa;
 280                         daa = dax_direct_access(wc->ssd_dev->dax_dev, offset + i, p - i,
 281                                                 NULL, &pfn);
 282                         if (daa <= 0) {
 283                                 r = daa ? daa : -EINVAL;
 284                                 goto err3;
 285                         }
 286                         if (!pfn_t_has_page(pfn)) {
 287                                 r = -EOPNOTSUPP;
 288                                 goto err3;
 289                         }
 290                         while (daa-- && i < p) {
 291                                 pages[i++] = pfn_t_to_page(pfn);
 292                                 pfn.val++;
 293                                 if (!(i & 15))
 294                                         cond_resched();
 295                         }
 296                 } while (i < p);
 297                 wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
 298                 if (!wc->memory_map) {
 299                         r = -ENOMEM;
 300                         goto err3;
 301                 }
 302                 kvfree(pages);
 303                 wc->memory_vmapped = true;
 304         }
 305
 306         dax_read_unlock(id);
 307
 308         wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT;
 309         wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT;
 310
 311         return 0;
 312 err3:
 313         kvfree(pages);
 314 err2:
 315         dax_read_unlock(id);
 316 err1:
 317         return r;
 318 }
 319 #else
 320 static int persistent_memory_claim(struct dm_writecache *wc)
 321 {
 322         return -EOPNOTSUPP;
 323 }
 324 #endif
 325
 326 static void persistent_memory_release(struct dm_writecache *wc)
 327 {
 328         if (wc->memory_vmapped)
 329                 vunmap(wc->memory_map - ((size_t)wc->start_sector << SECTOR_SHIFT));
 330 }
 331
 332 static struct page *persistent_memory_page(void *addr)
 333 {
 334         if (is_vmalloc_addr(addr))
 335                 return vmalloc_to_page(addr);
 336         else
 337                 return virt_to_page(addr);
 338 }
 339
 340 static unsigned persistent_memory_page_offset(void *addr)
 341 {
 342         return (unsigned long)addr & (PAGE_SIZE - 1);
 343 }
 344
 345 static void persistent_memory_flush_cache(void *ptr, size_t size)
 346 {
 347         if (is_vmalloc_addr(ptr))
 348                 flush_kernel_vmap_range(ptr, size);
 349 }
 350
 351 static void persistent_memory_invalidate_cache(void *ptr, size_t size)
 352 {
 353         if (is_vmalloc_addr(ptr))
 354                 invalidate_kernel_vmap_range(ptr, size);
 355 }
 356
 357 static struct wc_memory_superblock *sb(struct dm_writecache *wc)
 358 {
 359         return wc->memory_map;
 360 }
 361
 362 static struct wc_memory_entry *memory_entry(struct dm_writecache *wc, struct wc_entry *e)
 363 {
 364         return &sb(wc)->entries[e->index];
 365 }
 366
 367 static void *memory_data(struct dm_writecache *wc, struct wc_entry *e)
 368 {
 369         return (char *)wc->block_start + (e->index << wc->block_size_bits);
 370 }
 371
 372 static sector_t cache_sector(struct dm_writecache *wc, struct wc_entry *e)
 373 {
 374         return wc->start_sector + wc->metadata_sectors +
 375                 ((sector_t)e->index << (wc->block_size_bits - SECTOR_SHIFT));
 376 }
 377
 378 static uint64_t read_original_sector(struct dm_writecache *wc, struct wc_entry *e)
 379 {
 380 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 381         return e->original_sector;
 382 #else
 383         return le64_to_cpu(memory_entry(wc, e)->original_sector);
 384 #endif
 385 }
 386
 387 static uint64_t read_seq_count(struct dm_writecache *wc, struct wc_entry *e)
 388 {
 389 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 390         return e->seq_count;
 391 #else
 392         return le64_to_cpu(memory_entry(wc, e)->seq_count);
 393 #endif
 394 }
 395
 396 static void clear_seq_count(struct dm_writecache *wc, struct wc_entry *e)
 397 {
 398 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 399         e->seq_count = -1;
 400 #endif
 401         pmem_assign(memory_entry(wc, e)->seq_count, cpu_to_le64(-1));
 402 }
 403
 404 static void write_original_sector_seq_count(struct dm_writecache *wc, struct wc_entry *e,
 405                                             uint64_t original_sector, uint64_t seq_count)
 406 {
 407         struct wc_memory_entry me;
 408 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 409         e->original_sector = original_sector;
 410         e->seq_count = seq_count;
 411 #endif
 412         me.original_sector = cpu_to_le64(original_sector);
 413         me.seq_count = cpu_to_le64(seq_count);
 414         pmem_assign(*memory_entry(wc, e), me);
 415 }
 416
 417 #define writecache_error(wc, err, msg, arg...)                          \
 418 do {                                                                    \
 419         if (!cmpxchg(&(wc)->error, 0, err))                             \
 420                 DMERR(msg, ##arg);                                      \
 421         wake_up(&(wc)->freelist_wait);                                  \
 422 } while (0)
 423
 424 #define writecache_has_error(wc)        (unlikely(READ_ONCE((wc)->error)))
 425
 426 static void writecache_flush_all_metadata(struct dm_writecache *wc)
 427 {
 428         if (!WC_MODE_PMEM(wc))
 429                 memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
 430 }
 431
 432 static void writecache_flush_region(struct dm_writecache *wc, void *ptr, size_t size)
 433 {
 434         if (!WC_MODE_PMEM(wc))
 435                 __set_bit(((char *)ptr - (char *)wc->memory_map) / BITMAP_GRANULARITY,
 436                           wc->dirty_bitmap);
 437 }
 438
 439 static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev);
 440
 441 struct io_notify {
 442         struct dm_writecache *wc;
 443         struct completion c;
 444         atomic_t count;
 445 };
 446
 447 static void writecache_notify_io(unsigned long error, void *context)
 448 {
 449         struct io_notify *endio = context;
 450
 451         if (unlikely(error != 0))
 452                 writecache_error(endio->wc, -EIO, "error writing metadata");
 453         BUG_ON(atomic_read(&endio->count) <= 0);
 454         if (atomic_dec_and_test(&endio->count))
 455                 complete(&endio->c);
 456 }
 457
 458 static void writecache_wait_for_ios(struct dm_writecache *wc, int direction)
 459 {
 460         wait_event(wc->bio_in_progress_wait[direction],
 461                    !atomic_read(&wc->bio_in_progress[direction]));
 462 }
 463
 464 static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
 465 {
 466         struct dm_io_region region;
 467         struct dm_io_request req;
 468         struct io_notify endio = {
 469                 wc,
 470                 COMPLETION_INITIALIZER_ONSTACK(endio.c),
 471                 ATOMIC_INIT(1),
 472         };
 473         unsigned bitmap_bits = wc->dirty_bitmap_size * 8;
 474         unsigned i = 0;
 475
 476         while (1) {
 477                 unsigned j;
 478                 i = find_next_bit(wc->dirty_bitmap, bitmap_bits, i);
 479                 if (unlikely(i == bitmap_bits))
 480                         break;
 481                 j = find_next_zero_bit(wc->dirty_bitmap, bitmap_bits, i);
 482
 483                 region.bdev = wc->ssd_dev->bdev;
 484                 region.sector = (sector_t)i * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
 485                 region.count = (sector_t)(j - i) * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
 486
 487                 if (unlikely(region.sector >= wc->metadata_sectors))
 488                         break;
 489                 if (unlikely(region.sector + region.count > wc->metadata_sectors))
 490                         region.count = wc->metadata_sectors - region.sector;
 491
 492                 region.sector += wc->start_sector;
 493                 atomic_inc(&endio.count);
 494                 req.bi_op = REQ_OP_WRITE;
 495                 req.bi_op_flags = REQ_SYNC;
 496                 req.mem.type = DM_IO_VMA;
 497                 req.mem.ptr.vma = (char *)wc->memory_map + (size_t)i * BITMAP_GRANULARITY;
 498                 req.client = wc->dm_io;
 499                 req.notify.fn = writecache_notify_io;
 500                 req.notify.context = &endio;
 501
 502                 /* writing via async dm-io (implied by notify.fn above) won't return an error */
 503                 (void) dm_io(&req, 1, &region, NULL);
 504                 i = j;
 505         }
 506
 507         writecache_notify_io(0, &endio);
 508         wait_for_completion_io(&endio.c);
 509
 510         if (wait_for_ios)
 511                 writecache_wait_for_ios(wc, WRITE);
 512
 513         writecache_disk_flush(wc, wc->ssd_dev);
 514
 515         memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size);
 516 }
 517
 518 static void ssd_commit_superblock(struct dm_writecache *wc)
 519 {
 520         int r;
 521         struct dm_io_region region;
 522         struct dm_io_request req;
 523
 524         region.bdev = wc->ssd_dev->bdev;
 525         region.sector = 0;
 526         region.count = PAGE_SIZE;
 527
 528         if (unlikely(region.sector + region.count > wc->metadata_sectors))
 529                 region.count = wc->metadata_sectors - region.sector;
 530
 531         region.sector += wc->start_sector;
 532
 533         req.bi_op = REQ_OP_WRITE;
 534         req.bi_op_flags = REQ_SYNC | REQ_FUA;
 535         req.mem.type = DM_IO_VMA;
 536         req.mem.ptr.vma = (char *)wc->memory_map;
 537         req.client = wc->dm_io;
 538         req.notify.fn = NULL;
 539         req.notify.context = NULL;
 540
 541         r = dm_io(&req, 1, &region, NULL);
 542         if (unlikely(r))
 543                 writecache_error(wc, r, "error writing superblock");
 544 }
 545
 546 static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
 547 {
 548         if (WC_MODE_PMEM(wc))
 549                 pmem_wmb();
 550         else
 551                 ssd_commit_flushed(wc, wait_for_ios);
 552 }
 553
 554 static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev)
 555 {
 556         int r;
 557         struct dm_io_region region;
 558         struct dm_io_request req;
 559
 560         region.bdev = dev->bdev;
 561         region.sector = 0;
 562         region.count = 0;
 563         req.bi_op = REQ_OP_WRITE;
 564         req.bi_op_flags = REQ_PREFLUSH;
 565         req.mem.type = DM_IO_KMEM;
 566         req.mem.ptr.addr = NULL;
 567         req.client = wc->dm_io;
 568         req.notify.fn = NULL;
 569
 570         r = dm_io(&req, 1, &region, NULL);
 571         if (unlikely(r))
 572                 writecache_error(wc, r, "error flushing metadata: %d", r);
 573 }
 574
 575 #define WFE_RETURN_FOLLOWING    1
 576 #define WFE_LOWEST_SEQ          2
 577
 578 static struct wc_entry *writecache_find_entry(struct dm_writecache *wc,
 579                                               uint64_t block, int flags)
 580 {
 581         struct wc_entry *e;
 582         struct rb_node *node = wc->tree.rb_node;
 583
 584         if (unlikely(!node))
 585                 return NULL;
 586
 587         while (1) {
 588                 e = container_of(node, struct wc_entry, rb_node);
 589                 if (read_original_sector(wc, e) == block)
 590                         break;
 591
 592                 node = (read_original_sector(wc, e) >= block ?
 593                         e->rb_node.rb_left : e->rb_node.rb_right);
 594                 if (unlikely(!node)) {
 595                         if (!(flags & WFE_RETURN_FOLLOWING))
 596                                 return NULL;
 597                         if (read_original_sector(wc, e) >= block) {
 598                                 return e;
 599                         } else {
 600                                 node = rb_next(&e->rb_node);
 601                                 if (unlikely(!node))
 602                                         return NULL;
 603                                 e = container_of(node, struct wc_entry, rb_node);
 604                                 return e;
 605                         }
 606                 }
 607         }
 608
 609         while (1) {
 610                 struct wc_entry *e2;
 611                 if (flags & WFE_LOWEST_SEQ)
 612                         node = rb_prev(&e->rb_node);
 613                 else
 614                         node = rb_next(&e->rb_node);
 615                 if (unlikely(!node))
 616                         return e;
 617                 e2 = container_of(node, struct wc_entry, rb_node);
 618                 if (read_original_sector(wc, e2) != block)
 619                         return e;
 620                 e = e2;
 621         }
 622 }
 623
 624 static void writecache_insert_entry(struct dm_writecache *wc, struct wc_entry *ins)
 625 {
 626         struct wc_entry *e;
 627         struct rb_node **node = &wc->tree.rb_node, *parent = NULL;
 628
 629         while (*node) {
 630                 e = container_of(*node, struct wc_entry, rb_node);
 631                 parent = &e->rb_node;
 632                 if (read_original_sector(wc, e) > read_original_sector(wc, ins))
 633                         node = &parent->rb_left;
 634                 else
 635                         node = &parent->rb_right;
 636         }
 637         rb_link_node(&ins->rb_node, parent, node);
 638         rb_insert_color(&ins->rb_node, &wc->tree);
 639         list_add(&ins->lru, &wc->lru);
 640         ins->age = jiffies;
 641 }
 642
 643 static void writecache_unlink(struct dm_writecache *wc, struct wc_entry *e)
 644 {
 645         list_del(&e->lru);
 646         rb_erase(&e->rb_node, &wc->tree);
 647 }
 648
 649 static void writecache_add_to_freelist(struct dm_writecache *wc, struct wc_entry *e)
 650 {
 651         if (WC_MODE_SORT_FREELIST(wc)) {
 652                 struct rb_node **node = &wc->freetree.rb_node, *parent = NULL;
 653                 if (unlikely(!*node))
 654                         wc->current_free = e;
 655                 while (*node) {
 656                         parent = *node;
 657                         if (&e->rb_node < *node)
 658                                 node = &parent->rb_left;
 659                         else
 660                                 node = &parent->rb_right;
 661                 }
 662                 rb_link_node(&e->rb_node, parent, node);
 663                 rb_insert_color(&e->rb_node, &wc->freetree);
 664         } else {
 665                 list_add_tail(&e->lru, &wc->freelist);
 666         }
 667         wc->freelist_size++;
 668 }
 669
 670 static inline void writecache_verify_watermark(struct dm_writecache *wc)
 671 {
 672         if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
 673                 queue_work(wc->writeback_wq, &wc->writeback_work);
 674 }
 675
 676 static void writecache_max_age_timer(struct timer_list *t)
 677 {
 678         struct dm_writecache *wc = from_timer(wc, t, max_age_timer);
 679
 680         if (!dm_suspended(wc->ti) && !writecache_has_error(wc)) {
 681                 queue_work(wc->writeback_wq, &wc->writeback_work);
 682                 mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
 683         }
 684 }
 685
 686 static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc, sector_t expected_sector)
 687 {
 688         struct wc_entry *e;
 689
 690         if (WC_MODE_SORT_FREELIST(wc)) {
 691                 struct rb_node *next;
 692                 if (unlikely(!wc->current_free))
 693                         return NULL;
 694                 e = wc->current_free;
 695                 if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
 696                         return NULL;
 697                 next = rb_next(&e->rb_node);
 698                 rb_erase(&e->rb_node, &wc->freetree);
 699                 if (unlikely(!next))
 700                         next = rb_first(&wc->freetree);
 701                 wc->current_free = next ? container_of(next, struct wc_entry, rb_node) : NULL;
 702         } else {
 703                 if (unlikely(list_empty(&wc->freelist)))
 704                         return NULL;
 705                 e = container_of(wc->freelist.next, struct wc_entry, lru);
 706                 if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
 707                         return NULL;
 708                 list_del(&e->lru);
 709         }
 710         wc->freelist_size--;
 711
 712         writecache_verify_watermark(wc);
 713
 714         return e;
 715 }
 716
 717 static void writecache_free_entry(struct dm_writecache *wc, struct wc_entry *e)
 718 {
 719         writecache_unlink(wc, e);
 720         writecache_add_to_freelist(wc, e);
 721         clear_seq_count(wc, e);
 722         writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
 723         if (unlikely(waitqueue_active(&wc->freelist_wait)))
 724                 wake_up(&wc->freelist_wait);
 725 }
 726
 727 static void writecache_wait_on_freelist(struct dm_writecache *wc)
 728 {
 729         DEFINE_WAIT(wait);
 730
 731         prepare_to_wait(&wc->freelist_wait, &wait, TASK_UNINTERRUPTIBLE);
 732         wc_unlock(wc);
 733         io_schedule();
 734         finish_wait(&wc->freelist_wait, &wait);
 735         wc_lock(wc);
 736 }
 737
 738 static void writecache_poison_lists(struct dm_writecache *wc)
 739 {
 740         /*
 741          * Catch incorrect access to these values while the device is suspended.
 742          */
 743         memset(&wc->tree, -1, sizeof wc->tree);
 744         wc->lru.next = LIST_POISON1;
 745         wc->lru.prev = LIST_POISON2;
 746         wc->freelist.next = LIST_POISON1;
 747         wc->freelist.prev = LIST_POISON2;
 748 }
 749
 750 static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
 751 {
 752         writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
 753         if (WC_MODE_PMEM(wc))
 754                 writecache_flush_region(wc, memory_data(wc, e), wc->block_size);
 755 }
 756
 757 static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
 758 {
 759         return read_seq_count(wc, e) < wc->seq_count;
 760 }
 761
 762 static void writecache_flush(struct dm_writecache *wc)
 763 {
 764         struct wc_entry *e, *e2;
 765         bool need_flush_after_free;
 766
 767         wc->uncommitted_blocks = 0;
 768         del_timer(&wc->autocommit_timer);
 769
 770         if (list_empty(&wc->lru))
 771                 return;
 772
 773         e = container_of(wc->lru.next, struct wc_entry, lru);
 774         if (writecache_entry_is_committed(wc, e)) {
 775                 if (wc->overwrote_committed) {
 776                         writecache_wait_for_ios(wc, WRITE);
 777                         writecache_disk_flush(wc, wc->ssd_dev);
 778                         wc->overwrote_committed = false;
 779                 }
 780                 return;
 781         }
 782         while (1) {
 783                 writecache_flush_entry(wc, e);
 784                 if (unlikely(e->lru.next == &wc->lru))
 785                         break;
 786                 e2 = container_of(e->lru.next, struct wc_entry, lru);
 787                 if (writecache_entry_is_committed(wc, e2))
 788                         break;
 789                 e = e2;
 790                 cond_resched();
 791         }
 792         writecache_commit_flushed(wc, true);
 793
 794         wc->seq_count++;
 795         pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
 796         if (WC_MODE_PMEM(wc))
 797                 writecache_commit_flushed(wc, false);
 798         else
 799                 ssd_commit_superblock(wc);
 800
 801         wc->overwrote_committed = false;
 802
 803         need_flush_after_free = false;
 804         while (1) {
 805                 /* Free another committed entry with lower seq-count */
 806                 struct rb_node *rb_node = rb_prev(&e->rb_node);
 807
 808                 if (rb_node) {
 809                         e2 = container_of(rb_node, struct wc_entry, rb_node);
 810                         if (read_original_sector(wc, e2) == read_original_sector(wc, e) &&
 811                             likely(!e2->write_in_progress)) {
 812                                 writecache_free_entry(wc, e2);
 813                                 need_flush_after_free = true;
 814                         }
 815                 }
 816                 if (unlikely(e->lru.prev == &wc->lru))
 817                         break;
 818                 e = container_of(e->lru.prev, struct wc_entry, lru);
 819                 cond_resched();
 820         }
 821
 822         if (need_flush_after_free)
 823                 writecache_commit_flushed(wc, false);
 824 }
 825
 826 static void writecache_flush_work(struct work_struct *work)
 827 {
 828         struct dm_writecache *wc = container_of(work, struct dm_writecache, flush_work);
 829
 830         wc_lock(wc);
 831         writecache_flush(wc);
 832         wc_unlock(wc);
 833 }
 834
 835 static void writecache_autocommit_timer(struct timer_list *t)
 836 {
 837         struct dm_writecache *wc = from_timer(wc, t, autocommit_timer);
 838         if (!writecache_has_error(wc))
 839                 queue_work(wc->writeback_wq, &wc->flush_work);
 840 }
 841
 842 static void writecache_schedule_autocommit(struct dm_writecache *wc)
 843 {
 844         if (!timer_pending(&wc->autocommit_timer))
 845                 mod_timer(&wc->autocommit_timer, jiffies + wc->autocommit_jiffies);
 846 }
 847
 848 static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_t end)
 849 {
 850         struct wc_entry *e;
 851         bool discarded_something = false;
 852
 853         e = writecache_find_entry(wc, start, WFE_RETURN_FOLLOWING | WFE_LOWEST_SEQ);
 854         if (unlikely(!e))
 855                 return;
 856
 857         while (read_original_sector(wc, e) < end) {
 858                 struct rb_node *node = rb_next(&e->rb_node);
 859
 860                 if (likely(!e->write_in_progress)) {
 861                         if (!discarded_something) {
 862                                 if (!WC_MODE_PMEM(wc)) {
 863                                         writecache_wait_for_ios(wc, READ);
 864                                         writecache_wait_for_ios(wc, WRITE);
 865                                 }
 866                                 discarded_something = true;
 867                         }
 868                         if (!writecache_entry_is_committed(wc, e))
 869                                 wc->uncommitted_blocks--;
 870                         writecache_free_entry(wc, e);
 871                 }
 872
 873                 if (unlikely(!node))
 874                         break;
 875
 876                 e = container_of(node, struct wc_entry, rb_node);
 877         }
 878
 879         if (discarded_something)
 880                 writecache_commit_flushed(wc, false);
 881 }
 882
 883 static bool writecache_wait_for_writeback(struct dm_writecache *wc)
 884 {
 885         if (wc->writeback_size) {
 886                 writecache_wait_on_freelist(wc);
 887                 return true;
 888         }
 889         return false;
 890 }
 891
 892 static void writecache_suspend(struct dm_target *ti)
 893 {
 894         struct dm_writecache *wc = ti->private;
 895         bool flush_on_suspend;
 896
 897         del_timer_sync(&wc->autocommit_timer);
 898         del_timer_sync(&wc->max_age_timer);
 899
 900         wc_lock(wc);
 901         writecache_flush(wc);
 902         flush_on_suspend = wc->flush_on_suspend;
 903         if (flush_on_suspend) {
 904                 wc->flush_on_suspend = false;
 905                 wc->writeback_all++;
 906                 queue_work(wc->writeback_wq, &wc->writeback_work);
 907         }
 908         wc_unlock(wc);
 909
 910         drain_workqueue(wc->writeback_wq);
 911
 912         wc_lock(wc);
 913         if (flush_on_suspend)
 914                 wc->writeback_all--;
 915         while (writecache_wait_for_writeback(wc));
 916
 917         if (WC_MODE_PMEM(wc))
 918                 persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
 919
 920         writecache_poison_lists(wc);
 921
 922         wc_unlock(wc);
 923 }
 924
 925 static int writecache_alloc_entries(struct dm_writecache *wc)
 926 {
 927         size_t b;
 928
 929         if (wc->entries)
 930                 return 0;
 931         wc->entries = vmalloc(array_size(sizeof(struct wc_entry), wc->n_blocks));
 932         if (!wc->entries)
 933                 return -ENOMEM;
 934         for (b = 0; b < wc->n_blocks; b++) {
 935                 struct wc_entry *e = &wc->entries[b];
 936                 e->index = b;
 937                 e->write_in_progress = false;
 938                 cond_resched();
 939         }
 940
 941         return 0;
 942 }
 943
 944 static int writecache_read_metadata(struct dm_writecache *wc, sector_t n_sectors)
 945 {
 946         struct dm_io_region region;
 947         struct dm_io_request req;
 948
 949         region.bdev = wc->ssd_dev->bdev;
 950         region.sector = wc->start_sector;
 951         region.count = n_sectors;
 952         req.bi_op = REQ_OP_READ;
 953         req.bi_op_flags = REQ_SYNC;
 954         req.mem.type = DM_IO_VMA;
 955         req.mem.ptr.vma = (char *)wc->memory_map;
 956         req.client = wc->dm_io;
 957         req.notify.fn = NULL;
 958
 959         return dm_io(&req, 1, &region, NULL);
 960 }
 961
 962 static void writecache_resume(struct dm_target *ti)
 963 {
 964         struct dm_writecache *wc = ti->private;
 965         size_t b;
 966         bool need_flush = false;
 967         __le64 sb_seq_count;
 968         int r;
 969
 970         wc_lock(wc);
 971
 972         if (WC_MODE_PMEM(wc)) {
 973                 persistent_memory_invalidate_cache(wc->memory_map, wc->memory_map_size);
 974         } else {
 975                 r = writecache_read_metadata(wc, wc->metadata_sectors);
 976                 if (r) {
 977                         size_t sb_entries_offset;
 978                         writecache_error(wc, r, "unable to read metadata: %d", r);
 979                         sb_entries_offset = offsetof(struct wc_memory_superblock, entries);
 980                         memset((char *)wc->memory_map + sb_entries_offset, -1,
 981                                (wc->metadata_sectors << SECTOR_SHIFT) - sb_entries_offset);
 982                 }
 983         }
 984
 985         wc->tree = RB_ROOT;
 986         INIT_LIST_HEAD(&wc->lru);
 987         if (WC_MODE_SORT_FREELIST(wc)) {
 988                 wc->freetree = RB_ROOT;
 989                 wc->current_free = NULL;
 990         } else {
 991                 INIT_LIST_HEAD(&wc->freelist);
 992         }
 993         wc->freelist_size = 0;
 994
 995         r = copy_mc_to_kernel(&sb_seq_count, &sb(wc)->seq_count,
 996                               sizeof(uint64_t));
 997         if (r) {
 998                 writecache_error(wc, r, "hardware memory error when reading superblock: %d", r);
 999                 sb_seq_count = cpu_to_le64(0);
1000         }
1001         wc->seq_count = le64_to_cpu(sb_seq_count);
1002
1003 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
1004         for (b = 0; b < wc->n_blocks; b++) {
1005                 struct wc_entry *e = &wc->entries[b];
1006                 struct wc_memory_entry wme;
1007                 if (writecache_has_error(wc)) {
1008                         e->original_sector = -1;
1009                         e->seq_count = -1;
1010                         continue;
1011                 }
1012                 r = copy_mc_to_kernel(&wme, memory_entry(wc, e),
1013                                       sizeof(struct wc_memory_entry));
1014                 if (r) {
1015                         writecache_error(wc, r, "hardware memory error when reading metadata entry %lu: %d",
1016                                          (unsigned long)b, r);
1017                         e->original_sector = -1;
1018                         e->seq_count = -1;
1019                 } else {
1020                         e->original_sector = le64_to_cpu(wme.original_sector);
1021                         e->seq_count = le64_to_cpu(wme.seq_count);
1022                 }
1023                 cond_resched();
1024         }
1025 #endif
1026         for (b = 0; b < wc->n_blocks; b++) {
1027                 struct wc_entry *e = &wc->entries[b];
1028                 if (!writecache_entry_is_committed(wc, e)) {
1029                         if (read_seq_count(wc, e) != -1) {
1030 erase_this:
1031                                 clear_seq_count(wc, e);
1032                                 need_flush = true;
1033                         }
1034                         writecache_add_to_freelist(wc, e);
1035                 } else {
1036                         struct wc_entry *old;
1037
1038                         old = writecache_find_entry(wc, read_original_sector(wc, e), 0);
1039                         if (!old) {
1040                                 writecache_insert_entry(wc, e);
1041                         } else {
1042                                 if (read_seq_count(wc, old) == read_seq_count(wc, e)) {
1043                                         writecache_error(wc, -EINVAL,
1044                                                  "two identical entries, position %llu, sector %llu, sequence %llu",
1045                                                  (unsigned long long)b, (unsigned long long)read_original_sector(wc, e),
1046                                                  (unsigned long long)read_seq_count(wc, e));
1047                                 }
1048                                 if (read_seq_count(wc, old) > read_seq_count(wc, e)) {
1049                                         goto erase_this;
1050                                 } else {
1051                                         writecache_free_entry(wc, old);
1052                                         writecache_insert_entry(wc, e);
1053                                         need_flush = true;
1054                                 }
1055                         }
1056                 }
1057                 cond_resched();
1058         }
1059
1060         if (need_flush) {
1061                 writecache_flush_all_metadata(wc);
1062                 writecache_commit_flushed(wc, false);
1063         }
1064
1065         writecache_verify_watermark(wc);
1066
1067         if (wc->max_age != MAX_AGE_UNSPECIFIED)
1068                 mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
1069
1070         wc_unlock(wc);
1071 }
1072
1073 static int process_flush_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1074 {
1075         if (argc != 1)
1076                 return -EINVAL;
1077
1078         wc_lock(wc);
1079         if (dm_suspended(wc->ti)) {
1080                 wc_unlock(wc);
1081                 return -EBUSY;
1082         }
1083         if (writecache_has_error(wc)) {
1084                 wc_unlock(wc);
1085                 return -EIO;
1086         }
1087
1088         writecache_flush(wc);
1089         wc->writeback_all++;
1090         queue_work(wc->writeback_wq, &wc->writeback_work);
1091         wc_unlock(wc);
1092
1093         flush_workqueue(wc->writeback_wq);
1094
1095         wc_lock(wc);
1096         wc->writeback_all--;
1097         if (writecache_has_error(wc)) {
1098                 wc_unlock(wc);
1099                 return -EIO;
1100         }
1101         wc_unlock(wc);
1102
1103         return 0;
1104 }
1105
1106 static int process_flush_on_suspend_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1107 {
1108         if (argc != 1)
1109                 return -EINVAL;
1110
1111         wc_lock(wc);
1112         wc->flush_on_suspend = true;
1113         wc_unlock(wc);
1114
1115         return 0;
1116 }
1117
1118 static void activate_cleaner(struct dm_writecache *wc)
1119 {
1120         wc->flush_on_suspend = true;
1121         wc->cleaner = true;
1122         wc->freelist_high_watermark = wc->n_blocks;
1123         wc->freelist_low_watermark = wc->n_blocks;
1124 }
1125
1126 static int process_cleaner_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1127 {
1128         if (argc != 1)
1129                 return -EINVAL;
1130
1131         wc_lock(wc);
1132         activate_cleaner(wc);
1133         if (!dm_suspended(wc->ti))
1134                 writecache_verify_watermark(wc);
1135         wc_unlock(wc);
1136
1137         return 0;
1138 }
1139
1140 static int writecache_message(struct dm_target *ti, unsigned argc, char **argv,
1141                               char *result, unsigned maxlen)
1142 {
1143         int r = -EINVAL;
1144         struct dm_writecache *wc = ti->private;
1145
1146         if (!strcasecmp(argv[0], "flush"))
1147                 r = process_flush_mesg(argc, argv, wc);
1148         else if (!strcasecmp(argv[0], "flush_on_suspend"))
1149                 r = process_flush_on_suspend_mesg(argc, argv, wc);
1150         else if (!strcasecmp(argv[0], "cleaner"))
1151                 r = process_cleaner_mesg(argc, argv, wc);
1152         else
1153                 DMERR("unrecognised message received: %s", argv[0]);
1154
1155         return r;
1156 }
1157
1158 static void memcpy_flushcache_optimized(void *dest, void *source, size_t size)
1159 {
1160         /*
1161          * clflushopt performs better with block size 1024, 2048, 4096
1162          * non-temporal stores perform better with block size 512
1163          *
1164          * block size   512             1024            2048            4096
1165          * movnti       496 MB/s        642 MB/s        725 MB/s        744 MB/s
1166          * clflushopt   373 MB/s        688 MB/s        1.1 GB/s        1.2 GB/s
1167          *
1168          * We see that movnti performs better for 512-byte blocks, and
1169          * clflushopt performs better for 1024-byte and larger blocks. So, we
1170          * prefer clflushopt for sizes >= 768.
1171          *
1172          * NOTE: this happens to be the case now (with dm-writecache's single
1173          * threaded model) but re-evaluate this once memcpy_flushcache() is
1174          * enabled to use movdir64b which might invalidate this performance
1175          * advantage seen with cache-allocating-writes plus flushing.
1176          */
1177 #ifdef CONFIG_X86
1178         if (static_cpu_has(X86_FEATURE_CLFLUSHOPT) &&
1179             likely(boot_cpu_data.x86_clflush_size == 64) &&
1180             likely(size >= 768)) {
1181                 do {
1182                         memcpy((void *)dest, (void *)source, 64);
1183                         clflushopt((void *)dest);
1184                         dest += 64;
1185                         source += 64;
1186                         size -= 64;
1187                 } while (size >= 64);
1188                 return;
1189         }
1190 #endif
1191         memcpy_flushcache(dest, source, size);
1192 }
1193
1194 static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data)
1195 {
1196         void *buf;
1197         unsigned long flags;
1198         unsigned size;
1199         int rw = bio_data_dir(bio);
1200         unsigned remaining_size = wc->block_size;
1201
1202         do {
1203                 struct bio_vec bv = bio_iter_iovec(bio, bio->bi_iter);
1204                 buf = bvec_kmap_irq(&bv, &flags);
1205                 size = bv.bv_len;
1206                 if (unlikely(size > remaining_size))
1207                         size = remaining_size;
1208
1209                 if (rw == READ) {
1210                         int r;
1211                         r = copy_mc_to_kernel(buf, data, size);
1212                         flush_dcache_page(bio_page(bio));
1213                         if (unlikely(r)) {
1214                                 writecache_error(wc, r, "hardware memory error when reading data: %d", r);
1215                                 bio->bi_status = BLK_STS_IOERR;
1216                         }
1217                 } else {
1218                         flush_dcache_page(bio_page(bio));
1219                         memcpy_flushcache_optimized(data, buf, size);
1220                 }
1221
1222                 bvec_kunmap_irq(buf, &flags);
1223
1224                 data = (char *)data + size;
1225                 remaining_size -= size;
1226                 bio_advance(bio, size);
1227         } while (unlikely(remaining_size));
1228 }
1229
1230 static int writecache_flush_thread(void *data)
1231 {
1232         struct dm_writecache *wc = data;
1233
1234         while (1) {
1235                 struct bio *bio;
1236
1237                 wc_lock(wc);
1238                 bio = bio_list_pop(&wc->flush_list);
1239                 if (!bio) {
1240                         set_current_state(TASK_INTERRUPTIBLE);
1241                         wc_unlock(wc);
1242
1243                         if (unlikely(kthread_should_stop())) {
1244                                 set_current_state(TASK_RUNNING);
1245                                 break;
1246                         }
1247
1248                         schedule();
1249                         continue;
1250                 }
1251
1252                 if (bio_op(bio) == REQ_OP_DISCARD) {
1253                         writecache_discard(wc, bio->bi_iter.bi_sector,
1254                                            bio_end_sector(bio));
1255                         wc_unlock(wc);
1256                         bio_set_dev(bio, wc->dev->bdev);
1257                         submit_bio_noacct(bio);
1258                 } else {
1259                         writecache_flush(wc);
1260                         wc_unlock(wc);
1261                         if (writecache_has_error(wc))
1262                                 bio->bi_status = BLK_STS_IOERR;
1263                         bio_endio(bio);
1264                 }
1265         }
1266
1267         return 0;
1268 }
1269
1270 static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
1271 {
1272         if (bio_list_empty(&wc->flush_list))
1273                 wake_up_process(wc->flush_thread);
1274         bio_list_add(&wc->flush_list, bio);
1275 }
1276
1277 static int writecache_map(struct dm_target *ti, struct bio *bio)
1278 {
1279         struct wc_entry *e;
1280         struct dm_writecache *wc = ti->private;
1281
1282         bio->bi_private = NULL;
1283
1284         wc_lock(wc);
1285
1286         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
1287                 if (writecache_has_error(wc))
1288                         goto unlock_error;
1289                 if (WC_MODE_PMEM(wc)) {
1290                         writecache_flush(wc);
1291                         if (writecache_has_error(wc))
1292                                 goto unlock_error;
1293                         goto unlock_submit;
1294                 } else {
1295                         writecache_offload_bio(wc, bio);
1296                         goto unlock_return;
1297                 }
1298         }
1299
1300         bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
1301
1302         if (unlikely((((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
1303                                 (wc->block_size / 512 - 1)) != 0)) {
1304                 DMERR("I/O is not aligned, sector %llu, size %u, block size %u",
1305                       (unsigned long long)bio->bi_iter.bi_sector,
1306                       bio->bi_iter.bi_size, wc->block_size);
1307                 goto unlock_error;
1308         }
1309
1310         if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
1311                 if (writecache_has_error(wc))
1312                         goto unlock_error;
1313                 if (WC_MODE_PMEM(wc)) {
1314                         writecache_discard(wc, bio->bi_iter.bi_sector, bio_end_sector(bio));
1315                         goto unlock_remap_origin;
1316                 } else {
1317                         writecache_offload_bio(wc, bio);
1318                         goto unlock_return;
1319                 }
1320         }
1321
1322         if (bio_data_dir(bio) == READ) {
1323 read_next_block:
1324                 e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1325                 if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
1326                         if (WC_MODE_PMEM(wc)) {
1327                                 bio_copy_block(wc, bio, memory_data(wc, e));
1328                                 if (bio->bi_iter.bi_size)
1329                                         goto read_next_block;
1330                                 goto unlock_submit;
1331                         } else {
1332                                 dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
1333                                 bio_set_dev(bio, wc->ssd_dev->bdev);
1334                                 bio->bi_iter.bi_sector = cache_sector(wc, e);
1335                                 if (!writecache_entry_is_committed(wc, e))
1336                                         writecache_wait_for_ios(wc, WRITE);
1337                                 goto unlock_remap;
1338                         }
1339                 } else {
1340                         if (e) {
1341                                 sector_t next_boundary =
1342                                         read_original_sector(wc, e) - bio->bi_iter.bi_sector;
1343                                 if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
1344                                         dm_accept_partial_bio(bio, next_boundary);
1345                                 }
1346                         }
1347                         goto unlock_remap_origin;
1348                 }
1349         } else {
1350                 do {
1351                         bool found_entry = false;
1352                         if (writecache_has_error(wc))
1353                                 goto unlock_error;
1354                         e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
1355                         if (e) {
1356                                 if (!writecache_entry_is_committed(wc, e))
1357                                         goto bio_copy;
1358                                 if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
1359                                         wc->overwrote_committed = true;
1360                                         goto bio_copy;
1361                                 }
1362                                 found_entry = true;
1363                         } else {
1364                                 if (unlikely(wc->cleaner))
1365                                         goto direct_write;
1366                         }
1367                         e = writecache_pop_from_freelist(wc, (sector_t)-1);
1368                         if (unlikely(!e)) {
1369                                 if (!found_entry) {
1370 direct_write:
1371                                         e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1372                                         if (e) {
1373                                                 sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector;
1374                                                 BUG_ON(!next_boundary);
1375                                                 if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
1376                                                         dm_accept_partial_bio(bio, next_boundary);
1377                                                 }
1378                                         }
1379                                         goto unlock_remap_origin;
1380                                 }
1381                                 writecache_wait_on_freelist(wc);
1382                                 continue;
1383                         }
1384                         write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
1385                         writecache_insert_entry(wc, e);
1386                         wc->uncommitted_blocks++;
1387 bio_copy:
1388                         if (WC_MODE_PMEM(wc)) {
1389                                 bio_copy_block(wc, bio, memory_data(wc, e));
1390                         } else {
1391                                 unsigned bio_size = wc->block_size;
1392                                 sector_t start_cache_sec = cache_sector(wc, e);
1393                                 sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
1394
1395                                 while (bio_size < bio->bi_iter.bi_size) {
1396                                         struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
1397                                         if (!f)
1398                                                 break;
1399                                         write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
1400                                                                         (bio_size >> SECTOR_SHIFT), wc->seq_count);
1401                                         writecache_insert_entry(wc, f);
1402                                         wc->uncommitted_blocks++;
1403                                         bio_size += wc->block_size;
1404                                         current_cache_sec += wc->block_size >> SECTOR_SHIFT;
1405                                 }
1406
1407                                 bio_set_dev(bio, wc->ssd_dev->bdev);
1408                                 bio->bi_iter.bi_sector = start_cache_sec;
1409                                 dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
1410
1411                                 if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
1412                                         wc->uncommitted_blocks = 0;
1413                                         queue_work(wc->writeback_wq, &wc->flush_work);
1414                                 } else {
1415                                         writecache_schedule_autocommit(wc);
1416                                 }
1417                                 goto unlock_remap;
1418                         }
1419                 } while (bio->bi_iter.bi_size);
1420
1421                 if (unlikely(bio->bi_opf & REQ_FUA ||
1422                              wc->uncommitted_blocks >= wc->autocommit_blocks))
1423                         writecache_flush(wc);
1424                 else
1425                         writecache_schedule_autocommit(wc);
1426                 goto unlock_submit;
1427         }
1428
1429 unlock_remap_origin:
1430         bio_set_dev(bio, wc->dev->bdev);
1431         wc_unlock(wc);
1432         return DM_MAPIO_REMAPPED;
1433
1434 unlock_remap:
1435         /* make sure that writecache_end_io decrements bio_in_progress: */
1436         bio->bi_private = (void *)1;
1437         atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
1438         wc_unlock(wc);
1439         return DM_MAPIO_REMAPPED;
1440
1441 unlock_submit:
1442         wc_unlock(wc);
1443         bio_endio(bio);
1444         return DM_MAPIO_SUBMITTED;
1445
1446 unlock_return:
1447         wc_unlock(wc);
1448         return DM_MAPIO_SUBMITTED;
1449
1450 unlock_error:
1451         wc_unlock(wc);
1452         bio_io_error(bio);
1453         return DM_MAPIO_SUBMITTED;
1454 }
1455
1456 static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status)
1457 {
1458         struct dm_writecache *wc = ti->private;
1459
1460         if (bio->bi_private != NULL) {
1461                 int dir = bio_data_dir(bio);
1462                 if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
1463                         if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
1464                                 wake_up(&wc->bio_in_progress_wait[dir]);
1465         }
1466         return 0;
1467 }
1468
1469 static int writecache_iterate_devices(struct dm_target *ti,
1470                                       iterate_devices_callout_fn fn, void *data)
1471 {
1472         struct dm_writecache *wc = ti->private;
1473
1474         return fn(ti, wc->dev, 0, ti->len, data);
1475 }
1476
1477 static void writecache_io_hints(struct dm_target *ti, struct queue_limits *limits)
1478 {
1479         struct dm_writecache *wc = ti->private;
1480
1481         if (limits->logical_block_size < wc->block_size)
1482                 limits->logical_block_size = wc->block_size;
1483
1484         if (limits->physical_block_size < wc->block_size)
1485                 limits->physical_block_size = wc->block_size;
1486
1487         if (limits->io_min < wc->block_size)
1488                 limits->io_min = wc->block_size;
1489 }
1490
1491
1492 static void writecache_writeback_endio(struct bio *bio)
1493 {
1494         struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
1495         struct dm_writecache *wc = wb->wc;
1496         unsigned long flags;
1497
1498         raw_spin_lock_irqsave(&wc->endio_list_lock, flags);
1499         if (unlikely(list_empty(&wc->endio_list)))
1500                 wake_up_process(wc->endio_thread);
1501         list_add_tail(&wb->endio_entry, &wc->endio_list);
1502         raw_spin_unlock_irqrestore(&wc->endio_list_lock, flags);
1503 }
1504
1505 static void writecache_copy_endio(int read_err, unsigned long write_err, void *ptr)
1506 {
1507         struct copy_struct *c = ptr;
1508         struct dm_writecache *wc = c->wc;
1509
1510         c->error = likely(!(read_err | write_err)) ? 0 : -EIO;
1511
1512         raw_spin_lock_irq(&wc->endio_list_lock);
1513         if (unlikely(list_empty(&wc->endio_list)))
1514                 wake_up_process(wc->endio_thread);
1515         list_add_tail(&c->endio_entry, &wc->endio_list);
1516         raw_spin_unlock_irq(&wc->endio_list_lock);
1517 }
1518
1519 static void __writecache_endio_pmem(struct dm_writecache *wc, struct list_head *list)
1520 {
1521         unsigned i;
1522         struct writeback_struct *wb;
1523         struct wc_entry *e;
1524         unsigned long n_walked = 0;
1525
1526         do {
1527                 wb = list_entry(list->next, struct writeback_struct, endio_entry);
1528                 list_del(&wb->endio_entry);
1529
1530                 if (unlikely(wb->bio.bi_status != BLK_STS_OK))
1531                         writecache_error(wc, blk_status_to_errno(wb->bio.bi_status),
1532                                         "write error %d", wb->bio.bi_status);
1533                 i = 0;
1534                 do {
1535                         e = wb->wc_list[i];
1536                         BUG_ON(!e->write_in_progress);
1537                         e->write_in_progress = false;
1538                         INIT_LIST_HEAD(&e->lru);
1539                         if (!writecache_has_error(wc))
1540                                 writecache_free_entry(wc, e);
1541                         BUG_ON(!wc->writeback_size);
1542                         wc->writeback_size--;
1543                         n_walked++;
1544                         if (unlikely(n_walked >= ENDIO_LATENCY)) {
1545                                 writecache_commit_flushed(wc, false);
1546                                 wc_unlock(wc);
1547                                 wc_lock(wc);
1548                                 n_walked = 0;
1549                         }
1550                 } while (++i < wb->wc_list_n);
1551
1552                 if (wb->wc_list != wb->wc_list_inline)
1553                         kfree(wb->wc_list);
1554                 bio_put(&wb->bio);
1555         } while (!list_empty(list));
1556 }
1557
1558 static void __writecache_endio_ssd(struct dm_writecache *wc, struct list_head *list)
1559 {
1560         struct copy_struct *c;
1561         struct wc_entry *e;
1562
1563         do {
1564                 c = list_entry(list->next, struct copy_struct, endio_entry);
1565                 list_del(&c->endio_entry);
1566
1567                 if (unlikely(c->error))
1568                         writecache_error(wc, c->error, "copy error");
1569
1570                 e = c->e;
1571                 do {
1572                         BUG_ON(!e->write_in_progress);
1573                         e->write_in_progress = false;
1574                         INIT_LIST_HEAD(&e->lru);
1575                         if (!writecache_has_error(wc))
1576                                 writecache_free_entry(wc, e);
1577
1578                         BUG_ON(!wc->writeback_size);
1579                         wc->writeback_size--;
1580                         e++;
1581                 } while (--c->n_entries);
1582                 mempool_free(c, &wc->copy_pool);
1583         } while (!list_empty(list));
1584 }
1585
1586 static int writecache_endio_thread(void *data)
1587 {
1588         struct dm_writecache *wc = data;
1589
1590         while (1) {
1591                 struct list_head list;
1592
1593                 raw_spin_lock_irq(&wc->endio_list_lock);
1594                 if (!list_empty(&wc->endio_list))
1595                         goto pop_from_list;
1596                 set_current_state(TASK_INTERRUPTIBLE);
1597                 raw_spin_unlock_irq(&wc->endio_list_lock);
1598
1599                 if (unlikely(kthread_should_stop())) {
1600                         set_current_state(TASK_RUNNING);
1601                         break;
1602                 }
1603
1604                 schedule();
1605
1606                 continue;
1607
1608 pop_from_list:
1609                 list = wc->endio_list;
1610                 list.next->prev = list.prev->next = &list;
1611                 INIT_LIST_HEAD(&wc->endio_list);
1612                 raw_spin_unlock_irq(&wc->endio_list_lock);
1613
1614                 if (!WC_MODE_FUA(wc))
1615                         writecache_disk_flush(wc, wc->dev);
1616
1617                 wc_lock(wc);
1618
1619                 if (WC_MODE_PMEM(wc)) {
1620                         __writecache_endio_pmem(wc, &list);
1621                 } else {
1622                         __writecache_endio_ssd(wc, &list);
1623                         writecache_wait_for_ios(wc, READ);
1624                 }
1625
1626                 writecache_commit_flushed(wc, false);
1627
1628                 wc_unlock(wc);
1629         }
1630
1631         return 0;
1632 }
1633
1634 static bool wc_add_block(struct writeback_struct *wb, struct wc_entry *e, gfp_t gfp)
1635 {
1636         struct dm_writecache *wc = wb->wc;
1637         unsigned block_size = wc->block_size;
1638         void *address = memory_data(wc, e);
1639
1640         persistent_memory_flush_cache(address, block_size);
1641         return bio_add_page(&wb->bio, persistent_memory_page(address),
1642                             block_size, persistent_memory_page_offset(address)) != 0;
1643 }
1644
1645 struct writeback_list {
1646         struct list_head list;
1647         size_t size;
1648 };
1649
1650 static void __writeback_throttle(struct dm_writecache *wc, struct writeback_list *wbl)
1651 {
1652         if (unlikely(wc->max_writeback_jobs)) {
1653                 if (READ_ONCE(wc->writeback_size) - wbl->size >= wc->max_writeback_jobs) {
1654                         wc_lock(wc);
1655                         while (wc->writeback_size - wbl->size >= wc->max_writeback_jobs)
1656                                 writecache_wait_on_freelist(wc);
1657                         wc_unlock(wc);
1658                 }
1659         }
1660         cond_resched();
1661 }
1662
1663 static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeback_list *wbl)
1664 {
1665         struct wc_entry *e, *f;
1666         struct bio *bio;
1667         struct writeback_struct *wb;
1668         unsigned max_pages;
1669
1670         while (wbl->size) {
1671                 wbl->size--;
1672                 e = container_of(wbl->list.prev, struct wc_entry, lru);
1673                 list_del(&e->lru);
1674
1675                 max_pages = e->wc_list_contiguous;
1676
1677                 bio = bio_alloc_bioset(GFP_NOIO, max_pages, &wc->bio_set);
1678                 wb = container_of(bio, struct writeback_struct, bio);
1679                 wb->wc = wc;
1680                 bio->bi_end_io = writecache_writeback_endio;
1681                 bio_set_dev(bio, wc->dev->bdev);
1682                 bio->bi_iter.bi_sector = read_original_sector(wc, e);
1683                 if (max_pages <= WB_LIST_INLINE ||
1684                     unlikely(!(wb->wc_list = kmalloc_array(max_pages, sizeof(struct wc_entry *),
1685                                                            GFP_NOIO | __GFP_NORETRY |
1686                                                            __GFP_NOMEMALLOC | __GFP_NOWARN)))) {
1687                         wb->wc_list = wb->wc_list_inline;
1688                         max_pages = WB_LIST_INLINE;
1689                 }
1690
1691                 BUG_ON(!wc_add_block(wb, e, GFP_NOIO));
1692
1693                 wb->wc_list[0] = e;
1694                 wb->wc_list_n = 1;
1695
1696                 while (wbl->size && wb->wc_list_n < max_pages) {
1697                         f = container_of(wbl->list.prev, struct wc_entry, lru);
1698                         if (read_original_sector(wc, f) !=
1699                             read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1700                                 break;
1701                         if (!wc_add_block(wb, f, GFP_NOWAIT | __GFP_NOWARN))
1702                                 break;
1703                         wbl->size--;
1704                         list_del(&f->lru);
1705                         wb->wc_list[wb->wc_list_n++] = f;
1706                         e = f;
1707                 }
1708                 bio_set_op_attrs(bio, REQ_OP_WRITE, WC_MODE_FUA(wc) * REQ_FUA);
1709                 if (writecache_has_error(wc)) {
1710                         bio->bi_status = BLK_STS_IOERR;
1711                         bio_endio(bio);
1712                 } else {
1713                         submit_bio(bio);
1714                 }
1715
1716                 __writeback_throttle(wc, wbl);
1717         }
1718 }
1719
1720 static void __writecache_writeback_ssd(struct dm_writecache *wc, struct writeback_list *wbl)
1721 {
1722         struct wc_entry *e, *f;
1723         struct dm_io_region from, to;
1724         struct copy_struct *c;
1725
1726         while (wbl->size) {
1727                 unsigned n_sectors;
1728
1729                 wbl->size--;
1730                 e = container_of(wbl->list.prev, struct wc_entry, lru);
1731                 list_del(&e->lru);
1732
1733                 n_sectors = e->wc_list_contiguous << (wc->block_size_bits - SECTOR_SHIFT);
1734
1735                 from.bdev = wc->ssd_dev->bdev;
1736                 from.sector = cache_sector(wc, e);
1737                 from.count = n_sectors;
1738                 to.bdev = wc->dev->bdev;
1739                 to.sector = read_original_sector(wc, e);
1740                 to.count = n_sectors;
1741
1742                 c = mempool_alloc(&wc->copy_pool, GFP_NOIO);
1743                 c->wc = wc;
1744                 c->e = e;
1745                 c->n_entries = e->wc_list_contiguous;
1746
1747                 while ((n_sectors -= wc->block_size >> SECTOR_SHIFT)) {
1748                         wbl->size--;
1749                         f = container_of(wbl->list.prev, struct wc_entry, lru);
1750                         BUG_ON(f != e + 1);
1751                         list_del(&f->lru);
1752                         e = f;
1753                 }
1754
1755                 dm_kcopyd_copy(wc->dm_kcopyd, &from, 1, &to, 0, writecache_copy_endio, c);
1756
1757                 __writeback_throttle(wc, wbl);
1758         }
1759 }
1760
1761 static void writecache_writeback(struct work_struct *work)
1762 {
1763         struct dm_writecache *wc = container_of(work, struct dm_writecache, writeback_work);
1764         struct blk_plug plug;
1765         struct wc_entry *f, *g, *e = NULL;
1766         struct rb_node *node, *next_node;
1767         struct list_head skipped;
1768         struct writeback_list wbl;
1769         unsigned long n_walked;
1770
1771         wc_lock(wc);
1772 restart:
1773         if (writecache_has_error(wc)) {
1774                 wc_unlock(wc);
1775                 return;
1776         }
1777
1778         if (unlikely(wc->writeback_all)) {
1779                 if (writecache_wait_for_writeback(wc))
1780                         goto restart;
1781         }
1782
1783         if (wc->overwrote_committed) {
1784                 writecache_wait_for_ios(wc, WRITE);
1785         }
1786
1787         n_walked = 0;
1788         INIT_LIST_HEAD(&skipped);
1789         INIT_LIST_HEAD(&wbl.list);
1790         wbl.size = 0;
1791         while (!list_empty(&wc->lru) &&
1792                (wc->writeback_all ||
1793                 wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark ||
1794                 (jiffies - container_of(wc->lru.prev, struct wc_entry, lru)->age >=
1795                  wc->max_age - wc->max_age / MAX_AGE_DIV))) {
1796
1797                 n_walked++;
1798                 if (unlikely(n_walked > WRITEBACK_LATENCY) &&
1799                     likely(!wc->writeback_all) && likely(!dm_suspended(wc->ti))) {
1800                         queue_work(wc->writeback_wq, &wc->writeback_work);
1801                         break;
1802                 }
1803
1804                 if (unlikely(wc->writeback_all)) {
1805                         if (unlikely(!e)) {
1806                                 writecache_flush(wc);
1807                                 e = container_of(rb_first(&wc->tree), struct wc_entry, rb_node);
1808                         } else
1809                                 e = g;
1810                 } else
1811                         e = container_of(wc->lru.prev, struct wc_entry, lru);
1812                 BUG_ON(e->write_in_progress);
1813                 if (unlikely(!writecache_entry_is_committed(wc, e))) {
1814                         writecache_flush(wc);
1815                 }
1816                 node = rb_prev(&e->rb_node);
1817                 if (node) {
1818                         f = container_of(node, struct wc_entry, rb_node);
1819                         if (unlikely(read_original_sector(wc, f) ==
1820                                      read_original_sector(wc, e))) {
1821                                 BUG_ON(!f->write_in_progress);
1822                                 list_del(&e->lru);
1823                                 list_add(&e->lru, &skipped);
1824                                 cond_resched();
1825                                 continue;
1826                         }
1827                 }
1828                 wc->writeback_size++;
1829                 list_del(&e->lru);
1830                 list_add(&e->lru, &wbl.list);
1831                 wbl.size++;
1832                 e->write_in_progress = true;
1833                 e->wc_list_contiguous = 1;
1834
1835                 f = e;
1836
1837                 while (1) {
1838                         next_node = rb_next(&f->rb_node);
1839                         if (unlikely(!next_node))
1840                                 break;
1841                         g = container_of(next_node, struct wc_entry, rb_node);
1842                         if (unlikely(read_original_sector(wc, g) ==
1843                             read_original_sector(wc, f))) {
1844                                 f = g;
1845                                 continue;
1846                         }
1847                         if (read_original_sector(wc, g) !=
1848                             read_original_sector(wc, f) + (wc->block_size >> SECTOR_SHIFT))
1849                                 break;
1850                         if (unlikely(g->write_in_progress))
1851                                 break;
1852                         if (unlikely(!writecache_entry_is_committed(wc, g)))
1853                                 break;
1854
1855                         if (!WC_MODE_PMEM(wc)) {
1856                                 if (g != f + 1)
1857                                         break;
1858                         }
1859
1860                         n_walked++;
1861                         //if (unlikely(n_walked > WRITEBACK_LATENCY) && likely(!wc->writeback_all))
1862                         //      break;
1863
1864                         wc->writeback_size++;
1865                         list_del(&g->lru);
1866                         list_add(&g->lru, &wbl.list);
1867                         wbl.size++;
1868                         g->write_in_progress = true;
1869                         g->wc_list_contiguous = BIO_MAX_PAGES;
1870                         f = g;
1871                         e->wc_list_contiguous++;
1872                         if (unlikely(e->wc_list_contiguous == BIO_MAX_PAGES)) {
1873                                 if (unlikely(wc->writeback_all)) {
1874                                         next_node = rb_next(&f->rb_node);
1875                                         if (likely(next_node))
1876                                                 g = container_of(next_node, struct wc_entry, rb_node);
1877                                 }
1878                                 break;
1879                         }
1880                 }
1881                 cond_resched();
1882         }
1883
1884         if (!list_empty(&skipped)) {
1885                 list_splice_tail(&skipped, &wc->lru);
1886                 /*
1887                  * If we didn't do any progress, we must wait until some
1888                  * writeback finishes to avoid burning CPU in a loop
1889                  */
1890                 if (unlikely(!wbl.size))
1891                         writecache_wait_for_writeback(wc);
1892         }
1893
1894         wc_unlock(wc);
1895
1896         blk_start_plug(&plug);
1897
1898         if (WC_MODE_PMEM(wc))
1899                 __writecache_writeback_pmem(wc, &wbl);
1900         else
1901                 __writecache_writeback_ssd(wc, &wbl);
1902
1903         blk_finish_plug(&plug);
1904
1905         if (unlikely(wc->writeback_all)) {
1906                 wc_lock(wc);
1907                 while (writecache_wait_for_writeback(wc));
1908                 wc_unlock(wc);
1909         }
1910 }
1911
1912 static int calculate_memory_size(uint64_t device_size, unsigned block_size,
1913                                  size_t *n_blocks_p, size_t *n_metadata_blocks_p)
1914 {
1915         uint64_t n_blocks, offset;
1916         struct wc_entry e;
1917
1918         n_blocks = device_size;
1919         do_div(n_blocks, block_size + sizeof(struct wc_memory_entry));
1920
1921         while (1) {
1922                 if (!n_blocks)
1923                         return -ENOSPC;
1924                 /* Verify the following entries[n_blocks] won't overflow */
1925                 if (n_blocks >= ((size_t)-sizeof(struct wc_memory_superblock) /
1926                                  sizeof(struct wc_memory_entry)))
1927                         return -EFBIG;
1928                 offset = offsetof(struct wc_memory_superblock, entries[n_blocks]);
1929                 offset = (offset + block_size - 1) & ~(uint64_t)(block_size - 1);
1930                 if (offset + n_blocks * block_size <= device_size)
1931                         break;
1932                 n_blocks--;
1933         }
1934
1935         /* check if the bit field overflows */
1936         e.index = n_blocks;
1937         if (e.index != n_blocks)
1938                 return -EFBIG;
1939
1940         if (n_blocks_p)
1941                 *n_blocks_p = n_blocks;
1942         if (n_metadata_blocks_p)
1943                 *n_metadata_blocks_p = offset >> __ffs(block_size);
1944         return 0;
1945 }
1946
1947 static int init_memory(struct dm_writecache *wc)
1948 {
1949         size_t b;
1950         int r;
1951
1952         r = calculate_memory_size(wc->memory_map_size, wc->block_size, &wc->n_blocks, NULL);
1953         if (r)
1954                 return r;
1955
1956         r = writecache_alloc_entries(wc);
1957         if (r)
1958                 return r;
1959
1960         for (b = 0; b < ARRAY_SIZE(sb(wc)->padding); b++)
1961                 pmem_assign(sb(wc)->padding[b], cpu_to_le64(0));
1962         pmem_assign(sb(wc)->version, cpu_to_le32(MEMORY_SUPERBLOCK_VERSION));
1963         pmem_assign(sb(wc)->block_size, cpu_to_le32(wc->block_size));
1964         pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
1965         pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
1966
1967         for (b = 0; b < wc->n_blocks; b++) {
1968                 write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
1969                 cond_resched();
1970         }
1971
1972         writecache_flush_all_metadata(wc);
1973         writecache_commit_flushed(wc, false);
1974         pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
1975         writecache_flush_region(wc, &sb(wc)->magic, sizeof sb(wc)->magic);
1976         writecache_commit_flushed(wc, false);
1977
1978         return 0;
1979 }
1980
1981 static void writecache_dtr(struct dm_target *ti)
1982 {
1983         struct dm_writecache *wc = ti->private;
1984
1985         if (!wc)
1986                 return;
1987
1988         if (wc->endio_thread)
1989                 kthread_stop(wc->endio_thread);
1990
1991         if (wc->flush_thread)
1992                 kthread_stop(wc->flush_thread);
1993
1994         bioset_exit(&wc->bio_set);
1995
1996         mempool_exit(&wc->copy_pool);
1997
1998         if (wc->writeback_wq)
1999                 destroy_workqueue(wc->writeback_wq);
2000
2001         if (wc->dev)
2002                 dm_put_device(ti, wc->dev);
2003
2004         if (wc->ssd_dev)
2005                 dm_put_device(ti, wc->ssd_dev);
2006
2007         if (wc->entries)
2008                 vfree(wc->entries);
2009
2010         if (wc->memory_map) {
2011                 if (WC_MODE_PMEM(wc))
2012                         persistent_memory_release(wc);
2013                 else
2014                         vfree(wc->memory_map);
2015         }
2016
2017         if (wc->dm_kcopyd)
2018                 dm_kcopyd_client_destroy(wc->dm_kcopyd);
2019
2020         if (wc->dm_io)
2021                 dm_io_client_destroy(wc->dm_io);
2022
2023         if (wc->dirty_bitmap)
2024                 vfree(wc->dirty_bitmap);
2025
2026         kfree(wc);
2027 }
2028
2029 static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2030 {
2031         struct dm_writecache *wc;
2032         struct dm_arg_set as;
2033         const char *string;
2034         unsigned opt_params;
2035         size_t offset, data_size;
2036         int i, r;
2037         char dummy;
2038         int high_wm_percent = HIGH_WATERMARK;
2039         int low_wm_percent = LOW_WATERMARK;
2040         uint64_t x;
2041         struct wc_memory_superblock s;
2042
2043         static struct dm_arg _args[] = {
2044                 {0, 16, "Invalid number of feature args"},
2045         };
2046
2047         as.argc = argc;
2048         as.argv = argv;
2049
2050         wc = kzalloc(sizeof(struct dm_writecache), GFP_KERNEL);
2051         if (!wc) {
2052                 ti->error = "Cannot allocate writecache structure";
2053                 r = -ENOMEM;
2054                 goto bad;
2055         }
2056         ti->private = wc;
2057         wc->ti = ti;
2058
2059         mutex_init(&wc->lock);
2060         wc->max_age = MAX_AGE_UNSPECIFIED;
2061         writecache_poison_lists(wc);
2062         init_waitqueue_head(&wc->freelist_wait);
2063         timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0);
2064         timer_setup(&wc->max_age_timer, writecache_max_age_timer, 0);
2065
2066         for (i = 0; i < 2; i++) {
2067                 atomic_set(&wc->bio_in_progress[i], 0);
2068                 init_waitqueue_head(&wc->bio_in_progress_wait[i]);
2069         }
2070
2071         wc->dm_io = dm_io_client_create();
2072         if (IS_ERR(wc->dm_io)) {
2073                 r = PTR_ERR(wc->dm_io);
2074                 ti->error = "Unable to allocate dm-io client";
2075                 wc->dm_io = NULL;
2076                 goto bad;
2077         }
2078
2079         wc->writeback_wq = alloc_workqueue("writecache-writeback", WQ_MEM_RECLAIM, 1);
2080         if (!wc->writeback_wq) {
2081                 r = -ENOMEM;
2082                 ti->error = "Could not allocate writeback workqueue";
2083                 goto bad;
2084         }
2085         INIT_WORK(&wc->writeback_work, writecache_writeback);
2086         INIT_WORK(&wc->flush_work, writecache_flush_work);
2087
2088         raw_spin_lock_init(&wc->endio_list_lock);
2089         INIT_LIST_HEAD(&wc->endio_list);
2090         wc->endio_thread = kthread_create(writecache_endio_thread, wc, "writecache_endio");
2091         if (IS_ERR(wc->endio_thread)) {
2092                 r = PTR_ERR(wc->endio_thread);
2093                 wc->endio_thread = NULL;
2094                 ti->error = "Couldn't spawn endio thread";
2095                 goto bad;
2096         }
2097         wake_up_process(wc->endio_thread);
2098
2099         /*
2100          * Parse the mode (pmem or ssd)
2101          */
2102         string = dm_shift_arg(&as);
2103         if (!string)
2104                 goto bad_arguments;
2105
2106         if (!strcasecmp(string, "s")) {
2107                 wc->pmem_mode = false;
2108         } else if (!strcasecmp(string, "p")) {
2109 #ifdef DM_WRITECACHE_HAS_PMEM
2110                 wc->pmem_mode = true;
2111                 wc->writeback_fua = true;
2112 #else
2113                 /*
2114                  * If the architecture doesn't support persistent memory or
2115                  * the kernel doesn't support any DAX drivers, this driver can
2116                  * only be used in SSD-only mode.
2117                  */
2118                 r = -EOPNOTSUPP;
2119                 ti->error = "Persistent memory or DAX not supported on this system";
2120                 goto bad;
2121 #endif
2122         } else {
2123                 goto bad_arguments;
2124         }
2125
2126         if (WC_MODE_PMEM(wc)) {
2127                 r = bioset_init(&wc->bio_set, BIO_POOL_SIZE,
2128                                 offsetof(struct writeback_struct, bio),
2129                                 BIOSET_NEED_BVECS);
2130                 if (r) {
2131                         ti->error = "Could not allocate bio set";
2132                         goto bad;
2133                 }
2134         } else {
2135                 r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
2136                 if (r) {
2137                         ti->error = "Could not allocate mempool";
2138                         goto bad;
2139                 }
2140         }
2141
2142         /*
2143          * Parse the origin data device
2144          */
2145         string = dm_shift_arg(&as);
2146         if (!string)
2147                 goto bad_arguments;
2148         r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->dev);
2149         if (r) {
2150                 ti->error = "Origin data device lookup failed";
2151                 goto bad;
2152         }
2153
2154         /*
2155          * Parse cache data device (be it pmem or ssd)
2156          */
2157         string = dm_shift_arg(&as);
2158         if (!string)
2159                 goto bad_arguments;
2160
2161         r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->ssd_dev);
2162         if (r) {
2163                 ti->error = "Cache data device lookup failed";
2164                 goto bad;
2165         }
2166         wc->memory_map_size = i_size_read(wc->ssd_dev->bdev->bd_inode);
2167
2168         /*
2169          * Parse the cache block size
2170          */
2171         string = dm_shift_arg(&as);
2172         if (!string)
2173                 goto bad_arguments;
2174         if (sscanf(string, "%u%c", &wc->block_size, &dummy) != 1 ||
2175             wc->block_size < 512 || wc->block_size > PAGE_SIZE ||
2176             (wc->block_size & (wc->block_size - 1))) {
2177                 r = -EINVAL;
2178                 ti->error = "Invalid block size";
2179                 goto bad;
2180         }
2181         if (wc->block_size < bdev_logical_block_size(wc->dev->bdev) ||
2182             wc->block_size < bdev_logical_block_size(wc->ssd_dev->bdev)) {
2183                 r = -EINVAL;
2184                 ti->error = "Block size is smaller than device logical block size";
2185                 goto bad;
2186         }
2187         wc->block_size_bits = __ffs(wc->block_size);
2188
2189         wc->max_writeback_jobs = MAX_WRITEBACK_JOBS;
2190         wc->autocommit_blocks = !WC_MODE_PMEM(wc) ? AUTOCOMMIT_BLOCKS_SSD : AUTOCOMMIT_BLOCKS_PMEM;
2191         wc->autocommit_jiffies = msecs_to_jiffies(AUTOCOMMIT_MSEC);
2192
2193         /*
2194          * Parse optional arguments
2195          */
2196         r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
2197         if (r)
2198                 goto bad;
2199
2200         while (opt_params) {
2201                 string = dm_shift_arg(&as), opt_params--;
2202                 if (!strcasecmp(string, "start_sector") && opt_params >= 1) {
2203                         unsigned long long start_sector;
2204                         string = dm_shift_arg(&as), opt_params--;
2205                         if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
2206                                 goto invalid_optional;
2207                         wc->start_sector = start_sector;
2208                         if (wc->start_sector != start_sector ||
2209                             wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
2210                                 goto invalid_optional;
2211                 } else if (!strcasecmp(string, "high_watermark") && opt_params >= 1) {
2212                         string = dm_shift_arg(&as), opt_params--;
2213                         if (sscanf(string, "%d%c", &high_wm_percent, &dummy) != 1)
2214                                 goto invalid_optional;
2215                         if (high_wm_percent < 0 || high_wm_percent > 100)
2216                                 goto invalid_optional;
2217                         wc->high_wm_percent_set = true;
2218                 } else if (!strcasecmp(string, "low_watermark") && opt_params >= 1) {
2219                         string = dm_shift_arg(&as), opt_params--;
2220                         if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
2221                                 goto invalid_optional;
2222                         if (low_wm_percent < 0 || low_wm_percent > 100)
2223                                 goto invalid_optional;
2224                         wc->low_wm_percent_set = true;
2225                 } else if (!strcasecmp(string, "writeback_jobs") && opt_params >= 1) {
2226                         string = dm_shift_arg(&as), opt_params--;
2227                         if (sscanf(string, "%u%c", &wc->max_writeback_jobs, &dummy) != 1)
2228                                 goto invalid_optional;
2229                         wc->max_writeback_jobs_set = true;
2230                 } else if (!strcasecmp(string, "autocommit_blocks") && opt_params >= 1) {
2231                         string = dm_shift_arg(&as), opt_params--;
2232                         if (sscanf(string, "%u%c", &wc->autocommit_blocks, &dummy) != 1)
2233                                 goto invalid_optional;
2234                         wc->autocommit_blocks_set = true;
2235                 } else if (!strcasecmp(string, "autocommit_time") && opt_params >= 1) {
2236                         unsigned autocommit_msecs;
2237                         string = dm_shift_arg(&as), opt_params--;
2238                         if (sscanf(string, "%u%c", &autocommit_msecs, &dummy) != 1)
2239                                 goto invalid_optional;
2240                         if (autocommit_msecs > 3600000)
2241                                 goto invalid_optional;
2242                         wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs);
2243                         wc->autocommit_time_set = true;
2244                 } else if (!strcasecmp(string, "max_age") && opt_params >= 1) {
2245                         unsigned max_age_msecs;
2246                         string = dm_shift_arg(&as), opt_params--;
2247                         if (sscanf(string, "%u%c", &max_age_msecs, &dummy) != 1)
2248                                 goto invalid_optional;
2249                         if (max_age_msecs > 86400000)
2250                                 goto invalid_optional;
2251                         wc->max_age = msecs_to_jiffies(max_age_msecs);
2252                 } else if (!strcasecmp(string, "cleaner")) {
2253                         wc->cleaner = true;
2254                 } else if (!strcasecmp(string, "fua")) {
2255                         if (WC_MODE_PMEM(wc)) {
2256                                 wc->writeback_fua = true;
2257                                 wc->writeback_fua_set = true;
2258                         } else goto invalid_optional;
2259                 } else if (!strcasecmp(string, "nofua")) {
2260                         if (WC_MODE_PMEM(wc)) {
2261                                 wc->writeback_fua = false;
2262                                 wc->writeback_fua_set = true;
2263                         } else goto invalid_optional;
2264                 } else {
2265 invalid_optional:
2266                         r = -EINVAL;
2267                         ti->error = "Invalid optional argument";
2268                         goto bad;
2269                 }
2270         }
2271
2272         if (high_wm_percent < low_wm_percent) {
2273                 r = -EINVAL;
2274                 ti->error = "High watermark must be greater than or equal to low watermark";
2275                 goto bad;
2276         }
2277
2278         if (WC_MODE_PMEM(wc)) {
2279                 if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
2280                         r = -EOPNOTSUPP;
2281                         ti->error = "Asynchronous persistent memory not supported as pmem cache";
2282                         goto bad;
2283                 }
2284
2285                 r = persistent_memory_claim(wc);
2286                 if (r) {
2287                         ti->error = "Unable to map persistent memory for cache";
2288                         goto bad;
2289                 }
2290         } else {
2291                 size_t n_blocks, n_metadata_blocks;
2292                 uint64_t n_bitmap_bits;
2293
2294                 wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
2295
2296                 bio_list_init(&wc->flush_list);
2297                 wc->flush_thread = kthread_create(writecache_flush_thread, wc, "dm_writecache_flush");
2298                 if (IS_ERR(wc->flush_thread)) {
2299                         r = PTR_ERR(wc->flush_thread);
2300                         wc->flush_thread = NULL;
2301                         ti->error = "Couldn't spawn flush thread";
2302                         goto bad;
2303                 }
2304                 wake_up_process(wc->flush_thread);
2305
2306                 r = calculate_memory_size(wc->memory_map_size, wc->block_size,
2307                                           &n_blocks, &n_metadata_blocks);
2308                 if (r) {
2309                         ti->error = "Invalid device size";
2310                         goto bad;
2311                 }
2312
2313                 n_bitmap_bits = (((uint64_t)n_metadata_blocks << wc->block_size_bits) +
2314                                  BITMAP_GRANULARITY - 1) / BITMAP_GRANULARITY;
2315                 /* this is limitation of test_bit functions */
2316                 if (n_bitmap_bits > 1U << 31) {
2317                         r = -EFBIG;
2318                         ti->error = "Invalid device size";
2319                         goto bad;
2320                 }
2321
2322                 wc->memory_map = vmalloc(n_metadata_blocks << wc->block_size_bits);
2323                 if (!wc->memory_map) {
2324                         r = -ENOMEM;
2325                         ti->error = "Unable to allocate memory for metadata";
2326                         goto bad;
2327                 }
2328
2329                 wc->dm_kcopyd = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2330                 if (IS_ERR(wc->dm_kcopyd)) {
2331                         r = PTR_ERR(wc->dm_kcopyd);
2332                         ti->error = "Unable to allocate dm-kcopyd client";
2333                         wc->dm_kcopyd = NULL;
2334                         goto bad;
2335                 }
2336
2337                 wc->metadata_sectors = n_metadata_blocks << (wc->block_size_bits - SECTOR_SHIFT);
2338                 wc->dirty_bitmap_size = (n_bitmap_bits + BITS_PER_LONG - 1) /
2339                         BITS_PER_LONG * sizeof(unsigned long);
2340                 wc->dirty_bitmap = vzalloc(wc->dirty_bitmap_size);
2341                 if (!wc->dirty_bitmap) {
2342                         r = -ENOMEM;
2343                         ti->error = "Unable to allocate dirty bitmap";
2344                         goto bad;
2345                 }
2346
2347                 r = writecache_read_metadata(wc, wc->block_size >> SECTOR_SHIFT);
2348                 if (r) {
2349                         ti->error = "Unable to read first block of metadata";
2350                         goto bad;
2351                 }
2352         }
2353
2354         r = copy_mc_to_kernel(&s, sb(wc), sizeof(struct wc_memory_superblock));
2355         if (r) {
2356                 ti->error = "Hardware memory error when reading superblock";
2357                 goto bad;
2358         }
2359         if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
2360                 r = init_memory(wc);
2361                 if (r) {
2362                         ti->error = "Unable to initialize device";
2363                         goto bad;
2364                 }
2365                 r = copy_mc_to_kernel(&s, sb(wc),
2366                                       sizeof(struct wc_memory_superblock));
2367                 if (r) {
2368                         ti->error = "Hardware memory error when reading superblock";
2369                         goto bad;
2370                 }
2371         }
2372
2373         if (le32_to_cpu(s.magic) != MEMORY_SUPERBLOCK_MAGIC) {
2374                 ti->error = "Invalid magic in the superblock";
2375                 r = -EINVAL;
2376                 goto bad;
2377         }
2378
2379         if (le32_to_cpu(s.version) != MEMORY_SUPERBLOCK_VERSION) {
2380                 ti->error = "Invalid version in the superblock";
2381                 r = -EINVAL;
2382                 goto bad;
2383         }
2384
2385         if (le32_to_cpu(s.block_size) != wc->block_size) {
2386                 ti->error = "Block size does not match superblock";
2387                 r = -EINVAL;
2388                 goto bad;
2389         }
2390
2391         wc->n_blocks = le64_to_cpu(s.n_blocks);
2392
2393         offset = wc->n_blocks * sizeof(struct wc_memory_entry);
2394         if (offset / sizeof(struct wc_memory_entry) != le64_to_cpu(sb(wc)->n_blocks)) {
2395 overflow:
2396                 ti->error = "Overflow in size calculation";
2397                 r = -EINVAL;
2398                 goto bad;
2399         }
2400         offset += sizeof(struct wc_memory_superblock);
2401         if (offset < sizeof(struct wc_memory_superblock))
2402                 goto overflow;
2403         offset = (offset + wc->block_size - 1) & ~(size_t)(wc->block_size - 1);
2404         data_size = wc->n_blocks * (size_t)wc->block_size;
2405         if (!offset || (data_size / wc->block_size != wc->n_blocks) ||
2406             (offset + data_size < offset))
2407                 goto overflow;
2408         if (offset + data_size > wc->memory_map_size) {
2409                 ti->error = "Memory area is too small";
2410                 r = -EINVAL;
2411                 goto bad;
2412         }
2413
2414         wc->metadata_sectors = offset >> SECTOR_SHIFT;
2415         wc->block_start = (char *)sb(wc) + offset;
2416
2417         x = (uint64_t)wc->n_blocks * (100 - high_wm_percent);
2418         x += 50;
2419         do_div(x, 100);
2420         wc->freelist_high_watermark = x;
2421         x = (uint64_t)wc->n_blocks * (100 - low_wm_percent);
2422         x += 50;
2423         do_div(x, 100);
2424         wc->freelist_low_watermark = x;
2425
2426         if (wc->cleaner)
2427                 activate_cleaner(wc);
2428
2429         r = writecache_alloc_entries(wc);
2430         if (r) {
2431                 ti->error = "Cannot allocate memory";
2432                 goto bad;
2433         }
2434
2435         ti->num_flush_bios = 1;
2436         ti->flush_supported = true;
2437         ti->num_discard_bios = 1;
2438
2439         if (WC_MODE_PMEM(wc))
2440                 persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
2441
2442         return 0;
2443
2444 bad_arguments:
2445         r = -EINVAL;
2446         ti->error = "Bad arguments";
2447 bad:
2448         writecache_dtr(ti);
2449         return r;
2450 }
2451
2452 static void writecache_status(struct dm_target *ti, status_type_t type,
2453                               unsigned status_flags, char *result, unsigned maxlen)
2454 {
2455         struct dm_writecache *wc = ti->private;
2456         unsigned extra_args;
2457         unsigned sz = 0;
2458         uint64_t x;
2459
2460         switch (type) {
2461         case STATUSTYPE_INFO:
2462                 DMEMIT("%ld %llu %llu %llu", writecache_has_error(wc),
2463                        (unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
2464                        (unsigned long long)wc->writeback_size);
2465                 break;
2466         case STATUSTYPE_TABLE:
2467                 DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
2468                                 wc->dev->name, wc->ssd_dev->name, wc->block_size);
2469                 extra_args = 0;
2470                 if (wc->start_sector)
2471                         extra_args += 2;
2472                 if (wc->high_wm_percent_set && !wc->cleaner)
2473                         extra_args += 2;
2474                 if (wc->low_wm_percent_set && !wc->cleaner)
2475                         extra_args += 2;
2476                 if (wc->max_writeback_jobs_set)
2477                         extra_args += 2;
2478                 if (wc->autocommit_blocks_set)
2479                         extra_args += 2;
2480                 if (wc->autocommit_time_set)
2481                         extra_args += 2;
2482                 if (wc->max_age != MAX_AGE_UNSPECIFIED)
2483                         extra_args += 2;
2484                 if (wc->cleaner)
2485                         extra_args++;
2486                 if (wc->writeback_fua_set)
2487                         extra_args++;
2488
2489                 DMEMIT("%u", extra_args);
2490                 if (wc->start_sector)
2491                         DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
2492                 if (wc->high_wm_percent_set && !wc->cleaner) {
2493                         x = (uint64_t)wc->freelist_high_watermark * 100;
2494                         x += wc->n_blocks / 2;
2495                         do_div(x, (size_t)wc->n_blocks);
2496                         DMEMIT(" high_watermark %u", 100 - (unsigned)x);
2497                 }
2498                 if (wc->low_wm_percent_set && !wc->cleaner) {
2499                         x = (uint64_t)wc->freelist_low_watermark * 100;
2500                         x += wc->n_blocks / 2;
2501                         do_div(x, (size_t)wc->n_blocks);
2502                         DMEMIT(" low_watermark %u", 100 - (unsigned)x);
2503                 }
2504                 if (wc->max_writeback_jobs_set)
2505                         DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
2506                 if (wc->autocommit_blocks_set)
2507                         DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
2508                 if (wc->autocommit_time_set)
2509                         DMEMIT(" autocommit_time %u", jiffies_to_msecs(wc->autocommit_jiffies));
2510                 if (wc->max_age != MAX_AGE_UNSPECIFIED)
2511                         DMEMIT(" max_age %u", jiffies_to_msecs(wc->max_age));
2512                 if (wc->cleaner)
2513                         DMEMIT(" cleaner");
2514                 if (wc->writeback_fua_set)
2515                         DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
2516                 break;
2517         }
2518 }
2519
2520 static struct target_type writecache_target = {
2521         .name                   = "writecache",
2522         .version                = {1, 3, 0},
2523         .module                 = THIS_MODULE,
2524         .ctr                    = writecache_ctr,
2525         .dtr                    = writecache_dtr,
2526         .status                 = writecache_status,
2527         .postsuspend            = writecache_suspend,
2528         .resume                 = writecache_resume,
2529         .message                = writecache_message,
2530         .map                    = writecache_map,
2531         .end_io                 = writecache_end_io,
2532         .iterate_devices        = writecache_iterate_devices,
2533         .io_hints               = writecache_io_hints,
2534 };
2535
2536 static int __init dm_writecache_init(void)
2537 {
2538         int r;
2539
2540         r = dm_register_target(&writecache_target);
2541         if (r < 0) {
2542                 DMERR("register failed %d", r);
2543                 return r;
2544         }
2545
2546         return 0;
2547 }
2548
2549 static void __exit dm_writecache_exit(void)
2550 {
2551         dm_unregister_target(&writecache_target);
2552 }
2553
2554 module_init(dm_writecache_init);
2555 module_exit(dm_writecache_exit);
2556
2557 MODULE_DESCRIPTION(DM_NAME " writecache target");
2558 MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
2559 MODULE_LICENSE("GPL");