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 #include <linux/delay.h>
  19 #include "dm-io-tracker.h"
  20
  21 #define DM_MSG_PREFIX "writecache"
  22
  23 #define HIGH_WATERMARK                  50
  24 #define LOW_WATERMARK                   45
  25 #define MAX_WRITEBACK_JOBS              min(0x10000000 / PAGE_SIZE, totalram_pages() / 16)
  26 #define ENDIO_LATENCY                   16
  27 #define WRITEBACK_LATENCY               64
  28 #define AUTOCOMMIT_BLOCKS_SSD           65536
  29 #define AUTOCOMMIT_BLOCKS_PMEM          64
  30 #define AUTOCOMMIT_MSEC                 1000
  31 #define MAX_AGE_DIV                     16
  32 #define MAX_AGE_UNSPECIFIED             -1UL
  33 #define PAUSE_WRITEBACK                 (HZ * 3)
  34
  35 #define BITMAP_GRANULARITY      65536
  36 #if BITMAP_GRANULARITY < PAGE_SIZE
  37 #undef BITMAP_GRANULARITY
  38 #define BITMAP_GRANULARITY      PAGE_SIZE
  39 #endif
  40
  41 #if IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_FS_DAX)
  42 #define DM_WRITECACHE_HAS_PMEM
  43 #endif
  44
  45 #ifdef DM_WRITECACHE_HAS_PMEM
  46 #define pmem_assign(dest, src)                                  \
  47 do {                                                            \
  48         typeof(dest) uniq = (src);                              \
  49         memcpy_flushcache(&(dest), &uniq, sizeof(dest));        \
  50 } while (0)
  51 #else
  52 #define pmem_assign(dest, src)  ((dest) = (src))
  53 #endif
  54
  55 #if IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC) && defined(DM_WRITECACHE_HAS_PMEM)
  56 #define DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
  57 #endif
  58
  59 #define MEMORY_SUPERBLOCK_MAGIC         0x23489321
  60 #define MEMORY_SUPERBLOCK_VERSION       1
  61
  62 struct wc_memory_entry {
  63         __le64 original_sector;
  64         __le64 seq_count;
  65 };
  66
  67 struct wc_memory_superblock {
  68         union {
  69                 struct {
  70                         __le32 magic;
  71                         __le32 version;
  72                         __le32 block_size;
  73                         __le32 pad;
  74                         __le64 n_blocks;
  75                         __le64 seq_count;
  76                 };
  77                 __le64 padding[8];
  78         };
  79         struct wc_memory_entry entries[];
  80 };
  81
  82 struct wc_entry {
  83         struct rb_node rb_node;
  84         struct list_head lru;
  85         unsigned short wc_list_contiguous;
  86         bool write_in_progress
  87 #if BITS_PER_LONG == 64
  88                 :1
  89 #endif
  90         ;
  91         unsigned long index
  92 #if BITS_PER_LONG == 64
  93                 :47
  94 #endif
  95         ;
  96         unsigned long age;
  97 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
  98         uint64_t original_sector;
  99         uint64_t seq_count;
 100 #endif
 101 };
 102
 103 #ifdef DM_WRITECACHE_HAS_PMEM
 104 #define WC_MODE_PMEM(wc)                        ((wc)->pmem_mode)
 105 #define WC_MODE_FUA(wc)                         ((wc)->writeback_fua)
 106 #else
 107 #define WC_MODE_PMEM(wc)                        false
 108 #define WC_MODE_FUA(wc)                         false
 109 #endif
 110 #define WC_MODE_SORT_FREELIST(wc)               (!WC_MODE_PMEM(wc))
 111
 112 struct dm_writecache {
 113         struct mutex lock;
 114         struct list_head lru;
 115         union {
 116                 struct list_head freelist;
 117                 struct {
 118                         struct rb_root freetree;
 119                         struct wc_entry *current_free;
 120                 };
 121         };
 122         struct rb_root tree;
 123
 124         size_t freelist_size;
 125         size_t writeback_size;
 126         size_t freelist_high_watermark;
 127         size_t freelist_low_watermark;
 128         unsigned long max_age;
 129         unsigned long pause;
 130
 131         unsigned uncommitted_blocks;
 132         unsigned autocommit_blocks;
 133         unsigned max_writeback_jobs;
 134
 135         int error;
 136
 137         unsigned long autocommit_jiffies;
 138         struct timer_list autocommit_timer;
 139         struct wait_queue_head freelist_wait;
 140
 141         struct timer_list max_age_timer;
 142
 143         atomic_t bio_in_progress[2];
 144         struct wait_queue_head bio_in_progress_wait[2];
 145
 146         struct dm_target *ti;
 147         struct dm_dev *dev;
 148         struct dm_dev *ssd_dev;
 149         sector_t start_sector;
 150         void *memory_map;
 151         uint64_t memory_map_size;
 152         size_t metadata_sectors;
 153         size_t n_blocks;
 154         uint64_t seq_count;
 155         sector_t data_device_sectors;
 156         void *block_start;
 157         struct wc_entry *entries;
 158         unsigned block_size;
 159         unsigned char block_size_bits;
 160
 161         bool pmem_mode:1;
 162         bool writeback_fua:1;
 163
 164         bool overwrote_committed:1;
 165         bool memory_vmapped:1;
 166
 167         bool start_sector_set:1;
 168         bool high_wm_percent_set:1;
 169         bool low_wm_percent_set:1;
 170         bool max_writeback_jobs_set:1;
 171         bool autocommit_blocks_set:1;
 172         bool autocommit_time_set:1;
 173         bool max_age_set:1;
 174         bool writeback_fua_set:1;
 175         bool flush_on_suspend:1;
 176         bool cleaner:1;
 177         bool cleaner_set:1;
 178         bool metadata_only:1;
 179         bool pause_set:1;
 180
 181         unsigned high_wm_percent_value;
 182         unsigned low_wm_percent_value;
 183         unsigned autocommit_time_value;
 184         unsigned max_age_value;
 185         unsigned pause_value;
 186
 187         unsigned writeback_all;
 188         struct workqueue_struct *writeback_wq;
 189         struct work_struct writeback_work;
 190         struct work_struct flush_work;
 191
 192         struct dm_io_tracker iot;
 193
 194         struct dm_io_client *dm_io;
 195
 196         raw_spinlock_t endio_list_lock;
 197         struct list_head endio_list;
 198         struct task_struct *endio_thread;
 199
 200         struct task_struct *flush_thread;
 201         struct bio_list flush_list;
 202
 203         struct dm_kcopyd_client *dm_kcopyd;
 204         unsigned long *dirty_bitmap;
 205         unsigned dirty_bitmap_size;
 206
 207         struct bio_set bio_set;
 208         mempool_t copy_pool;
 209
 210         struct {
 211                 unsigned long long reads;
 212                 unsigned long long read_hits;
 213                 unsigned long long writes;
 214                 unsigned long long write_hits_uncommitted;
 215                 unsigned long long write_hits_committed;
 216                 unsigned long long writes_around;
 217                 unsigned long long writes_allocate;
 218                 unsigned long long writes_blocked_on_freelist;
 219                 unsigned long long flushes;
 220                 unsigned long long discards;
 221         } stats;
 222 };
 223
 224 #define WB_LIST_INLINE          16
 225
 226 struct writeback_struct {
 227         struct list_head endio_entry;
 228         struct dm_writecache *wc;
 229         struct wc_entry **wc_list;
 230         unsigned wc_list_n;
 231         struct wc_entry *wc_list_inline[WB_LIST_INLINE];
 232         struct bio bio;
 233 };
 234
 235 struct copy_struct {
 236         struct list_head endio_entry;
 237         struct dm_writecache *wc;
 238         struct wc_entry *e;
 239         unsigned n_entries;
 240         int error;
 241 };
 242
 243 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(dm_writecache_throttle,
 244                                             "A percentage of time allocated for data copying");
 245
 246 static void wc_lock(struct dm_writecache *wc)
 247 {
 248         mutex_lock(&wc->lock);
 249 }
 250
 251 static void wc_unlock(struct dm_writecache *wc)
 252 {
 253         mutex_unlock(&wc->lock);
 254 }
 255
 256 #ifdef DM_WRITECACHE_HAS_PMEM
 257 static int persistent_memory_claim(struct dm_writecache *wc)
 258 {
 259         int r;
 260         loff_t s;
 261         long p, da;
 262         pfn_t pfn;
 263         int id;
 264         struct page **pages;
 265         sector_t offset;
 266
 267         wc->memory_vmapped = false;
 268
 269         s = wc->memory_map_size;
 270         p = s >> PAGE_SHIFT;
 271         if (!p) {
 272                 r = -EINVAL;
 273                 goto err1;
 274         }
 275         if (p != s >> PAGE_SHIFT) {
 276                 r = -EOVERFLOW;
 277                 goto err1;
 278         }
 279
 280         offset = get_start_sect(wc->ssd_dev->bdev);
 281         if (offset & (PAGE_SIZE / 512 - 1)) {
 282                 r = -EINVAL;
 283                 goto err1;
 284         }
 285         offset >>= PAGE_SHIFT - 9;
 286
 287         id = dax_read_lock();
 288
 289         da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, DAX_ACCESS,
 290                         &wc->memory_map, &pfn);
 291         if (da < 0) {
 292                 wc->memory_map = NULL;
 293                 r = da;
 294                 goto err2;
 295         }
 296         if (!pfn_t_has_page(pfn)) {
 297                 wc->memory_map = NULL;
 298                 r = -EOPNOTSUPP;
 299                 goto err2;
 300         }
 301         if (da != p) {
 302                 long i;
 303                 wc->memory_map = NULL;
 304                 pages = kvmalloc_array(p, sizeof(struct page *), GFP_KERNEL);
 305                 if (!pages) {
 306                         r = -ENOMEM;
 307                         goto err2;
 308                 }
 309                 i = 0;
 310                 do {
 311                         long daa;
 312                         daa = dax_direct_access(wc->ssd_dev->dax_dev, offset + i,
 313                                         p - i, DAX_ACCESS, NULL, &pfn);
 314                         if (daa <= 0) {
 315                                 r = daa ? daa : -EINVAL;
 316                                 goto err3;
 317                         }
 318                         if (!pfn_t_has_page(pfn)) {
 319                                 r = -EOPNOTSUPP;
 320                                 goto err3;
 321                         }
 322                         while (daa-- && i < p) {
 323                                 pages[i++] = pfn_t_to_page(pfn);
 324                                 pfn.val++;
 325                                 if (!(i & 15))
 326                                         cond_resched();
 327                         }
 328                 } while (i < p);
 329                 wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
 330                 if (!wc->memory_map) {
 331                         r = -ENOMEM;
 332                         goto err3;
 333                 }
 334                 kvfree(pages);
 335                 wc->memory_vmapped = true;
 336         }
 337
 338         dax_read_unlock(id);
 339
 340         wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT;
 341         wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT;
 342
 343         return 0;
 344 err3:
 345         kvfree(pages);
 346 err2:
 347         dax_read_unlock(id);
 348 err1:
 349         return r;
 350 }
 351 #else
 352 static int persistent_memory_claim(struct dm_writecache *wc)
 353 {
 354         return -EOPNOTSUPP;
 355 }
 356 #endif
 357
 358 static void persistent_memory_release(struct dm_writecache *wc)
 359 {
 360         if (wc->memory_vmapped)
 361                 vunmap(wc->memory_map - ((size_t)wc->start_sector << SECTOR_SHIFT));
 362 }
 363
 364 static struct page *persistent_memory_page(void *addr)
 365 {
 366         if (is_vmalloc_addr(addr))
 367                 return vmalloc_to_page(addr);
 368         else
 369                 return virt_to_page(addr);
 370 }
 371
 372 static unsigned persistent_memory_page_offset(void *addr)
 373 {
 374         return (unsigned long)addr & (PAGE_SIZE - 1);
 375 }
 376
 377 static void persistent_memory_flush_cache(void *ptr, size_t size)
 378 {
 379         if (is_vmalloc_addr(ptr))
 380                 flush_kernel_vmap_range(ptr, size);
 381 }
 382
 383 static void persistent_memory_invalidate_cache(void *ptr, size_t size)
 384 {
 385         if (is_vmalloc_addr(ptr))
 386                 invalidate_kernel_vmap_range(ptr, size);
 387 }
 388
 389 static struct wc_memory_superblock *sb(struct dm_writecache *wc)
 390 {
 391         return wc->memory_map;
 392 }
 393
 394 static struct wc_memory_entry *memory_entry(struct dm_writecache *wc, struct wc_entry *e)
 395 {
 396         return &sb(wc)->entries[e->index];
 397 }
 398
 399 static void *memory_data(struct dm_writecache *wc, struct wc_entry *e)
 400 {
 401         return (char *)wc->block_start + (e->index << wc->block_size_bits);
 402 }
 403
 404 static sector_t cache_sector(struct dm_writecache *wc, struct wc_entry *e)
 405 {
 406         return wc->start_sector + wc->metadata_sectors +
 407                 ((sector_t)e->index << (wc->block_size_bits - SECTOR_SHIFT));
 408 }
 409
 410 static uint64_t read_original_sector(struct dm_writecache *wc, struct wc_entry *e)
 411 {
 412 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 413         return e->original_sector;
 414 #else
 415         return le64_to_cpu(memory_entry(wc, e)->original_sector);
 416 #endif
 417 }
 418
 419 static uint64_t read_seq_count(struct dm_writecache *wc, struct wc_entry *e)
 420 {
 421 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 422         return e->seq_count;
 423 #else
 424         return le64_to_cpu(memory_entry(wc, e)->seq_count);
 425 #endif
 426 }
 427
 428 static void clear_seq_count(struct dm_writecache *wc, struct wc_entry *e)
 429 {
 430 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 431         e->seq_count = -1;
 432 #endif
 433         pmem_assign(memory_entry(wc, e)->seq_count, cpu_to_le64(-1));
 434 }
 435
 436 static void write_original_sector_seq_count(struct dm_writecache *wc, struct wc_entry *e,
 437                                             uint64_t original_sector, uint64_t seq_count)
 438 {
 439         struct wc_memory_entry me;
 440 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 441         e->original_sector = original_sector;
 442         e->seq_count = seq_count;
 443 #endif
 444         me.original_sector = cpu_to_le64(original_sector);
 445         me.seq_count = cpu_to_le64(seq_count);
 446         pmem_assign(*memory_entry(wc, e), me);
 447 }
 448
 449 #define writecache_error(wc, err, msg, arg...)                          \
 450 do {                                                                    \
 451         if (!cmpxchg(&(wc)->error, 0, err))                             \
 452                 DMERR(msg, ##arg);                                      \
 453         wake_up(&(wc)->freelist_wait);                                  \
 454 } while (0)
 455
 456 #define writecache_has_error(wc)        (unlikely(READ_ONCE((wc)->error)))
 457
 458 static void writecache_flush_all_metadata(struct dm_writecache *wc)
 459 {
 460         if (!WC_MODE_PMEM(wc))
 461                 memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
 462 }
 463
 464 static void writecache_flush_region(struct dm_writecache *wc, void *ptr, size_t size)
 465 {
 466         if (!WC_MODE_PMEM(wc))
 467                 __set_bit(((char *)ptr - (char *)wc->memory_map) / BITMAP_GRANULARITY,
 468                           wc->dirty_bitmap);
 469 }
 470
 471 static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev);
 472
 473 struct io_notify {
 474         struct dm_writecache *wc;
 475         struct completion c;
 476         atomic_t count;
 477 };
 478
 479 static void writecache_notify_io(unsigned long error, void *context)
 480 {
 481         struct io_notify *endio = context;
 482
 483         if (unlikely(error != 0))
 484                 writecache_error(endio->wc, -EIO, "error writing metadata");
 485         BUG_ON(atomic_read(&endio->count) <= 0);
 486         if (atomic_dec_and_test(&endio->count))
 487                 complete(&endio->c);
 488 }
 489
 490 static void writecache_wait_for_ios(struct dm_writecache *wc, int direction)
 491 {
 492         wait_event(wc->bio_in_progress_wait[direction],
 493                    !atomic_read(&wc->bio_in_progress[direction]));
 494 }
 495
 496 static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
 497 {
 498         struct dm_io_region region;
 499         struct dm_io_request req;
 500         struct io_notify endio = {
 501                 wc,
 502                 COMPLETION_INITIALIZER_ONSTACK(endio.c),
 503                 ATOMIC_INIT(1),
 504         };
 505         unsigned bitmap_bits = wc->dirty_bitmap_size * 8;
 506         unsigned i = 0;
 507
 508         while (1) {
 509                 unsigned j;
 510                 i = find_next_bit(wc->dirty_bitmap, bitmap_bits, i);
 511                 if (unlikely(i == bitmap_bits))
 512                         break;
 513                 j = find_next_zero_bit(wc->dirty_bitmap, bitmap_bits, i);
 514
 515                 region.bdev = wc->ssd_dev->bdev;
 516                 region.sector = (sector_t)i * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
 517                 region.count = (sector_t)(j - i) * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
 518
 519                 if (unlikely(region.sector >= wc->metadata_sectors))
 520                         break;
 521                 if (unlikely(region.sector + region.count > wc->metadata_sectors))
 522                         region.count = wc->metadata_sectors - region.sector;
 523
 524                 region.sector += wc->start_sector;
 525                 atomic_inc(&endio.count);
 526                 req.bi_opf = REQ_OP_WRITE | REQ_SYNC;
 527                 req.mem.type = DM_IO_VMA;
 528                 req.mem.ptr.vma = (char *)wc->memory_map + (size_t)i * BITMAP_GRANULARITY;
 529                 req.client = wc->dm_io;
 530                 req.notify.fn = writecache_notify_io;
 531                 req.notify.context = &endio;
 532
 533                 /* writing via async dm-io (implied by notify.fn above) won't return an error */
 534                 (void) dm_io(&req, 1, &region, NULL);
 535                 i = j;
 536         }
 537
 538         writecache_notify_io(0, &endio);
 539         wait_for_completion_io(&endio.c);
 540
 541         if (wait_for_ios)
 542                 writecache_wait_for_ios(wc, WRITE);
 543
 544         writecache_disk_flush(wc, wc->ssd_dev);
 545
 546         memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size);
 547 }
 548
 549 static void ssd_commit_superblock(struct dm_writecache *wc)
 550 {
 551         int r;
 552         struct dm_io_region region;
 553         struct dm_io_request req;
 554
 555         region.bdev = wc->ssd_dev->bdev;
 556         region.sector = 0;
 557         region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT;
 558
 559         if (unlikely(region.sector + region.count > wc->metadata_sectors))
 560                 region.count = wc->metadata_sectors - region.sector;
 561
 562         region.sector += wc->start_sector;
 563
 564         req.bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_FUA;
 565         req.mem.type = DM_IO_VMA;
 566         req.mem.ptr.vma = (char *)wc->memory_map;
 567         req.client = wc->dm_io;
 568         req.notify.fn = NULL;
 569         req.notify.context = NULL;
 570
 571         r = dm_io(&req, 1, &region, NULL);
 572         if (unlikely(r))
 573                 writecache_error(wc, r, "error writing superblock");
 574 }
 575
 576 static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
 577 {
 578         if (WC_MODE_PMEM(wc))
 579                 pmem_wmb();
 580         else
 581                 ssd_commit_flushed(wc, wait_for_ios);
 582 }
 583
 584 static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev)
 585 {
 586         int r;
 587         struct dm_io_region region;
 588         struct dm_io_request req;
 589
 590         region.bdev = dev->bdev;
 591         region.sector = 0;
 592         region.count = 0;
 593         req.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
 594         req.mem.type = DM_IO_KMEM;
 595         req.mem.ptr.addr = NULL;
 596         req.client = wc->dm_io;
 597         req.notify.fn = NULL;
 598
 599         r = dm_io(&req, 1, &region, NULL);
 600         if (unlikely(r))
 601                 writecache_error(wc, r, "error flushing metadata: %d", r);
 602 }
 603
 604 #define WFE_RETURN_FOLLOWING    1
 605 #define WFE_LOWEST_SEQ          2
 606
 607 static struct wc_entry *writecache_find_entry(struct dm_writecache *wc,
 608                                               uint64_t block, int flags)
 609 {
 610         struct wc_entry *e;
 611         struct rb_node *node = wc->tree.rb_node;
 612
 613         if (unlikely(!node))
 614                 return NULL;
 615
 616         while (1) {
 617                 e = container_of(node, struct wc_entry, rb_node);
 618                 if (read_original_sector(wc, e) == block)
 619                         break;
 620
 621                 node = (read_original_sector(wc, e) >= block ?
 622                         e->rb_node.rb_left : e->rb_node.rb_right);
 623                 if (unlikely(!node)) {
 624                         if (!(flags & WFE_RETURN_FOLLOWING))
 625                                 return NULL;
 626                         if (read_original_sector(wc, e) >= block) {
 627                                 return e;
 628                         } else {
 629                                 node = rb_next(&e->rb_node);
 630                                 if (unlikely(!node))
 631                                         return NULL;
 632                                 e = container_of(node, struct wc_entry, rb_node);
 633                                 return e;
 634                         }
 635                 }
 636         }
 637
 638         while (1) {
 639                 struct wc_entry *e2;
 640                 if (flags & WFE_LOWEST_SEQ)
 641                         node = rb_prev(&e->rb_node);
 642                 else
 643                         node = rb_next(&e->rb_node);
 644                 if (unlikely(!node))
 645                         return e;
 646                 e2 = container_of(node, struct wc_entry, rb_node);
 647                 if (read_original_sector(wc, e2) != block)
 648                         return e;
 649                 e = e2;
 650         }
 651 }
 652
 653 static void writecache_insert_entry(struct dm_writecache *wc, struct wc_entry *ins)
 654 {
 655         struct wc_entry *e;
 656         struct rb_node **node = &wc->tree.rb_node, *parent = NULL;
 657
 658         while (*node) {
 659                 e = container_of(*node, struct wc_entry, rb_node);
 660                 parent = &e->rb_node;
 661                 if (read_original_sector(wc, e) > read_original_sector(wc, ins))
 662                         node = &parent->rb_left;
 663                 else
 664                         node = &parent->rb_right;
 665         }
 666         rb_link_node(&ins->rb_node, parent, node);
 667         rb_insert_color(&ins->rb_node, &wc->tree);
 668         list_add(&ins->lru, &wc->lru);
 669         ins->age = jiffies;
 670 }
 671
 672 static void writecache_unlink(struct dm_writecache *wc, struct wc_entry *e)
 673 {
 674         list_del(&e->lru);
 675         rb_erase(&e->rb_node, &wc->tree);
 676 }
 677
 678 static void writecache_add_to_freelist(struct dm_writecache *wc, struct wc_entry *e)
 679 {
 680         if (WC_MODE_SORT_FREELIST(wc)) {
 681                 struct rb_node **node = &wc->freetree.rb_node, *parent = NULL;
 682                 if (unlikely(!*node))
 683                         wc->current_free = e;
 684                 while (*node) {
 685                         parent = *node;
 686                         if (&e->rb_node < *node)
 687                                 node = &parent->rb_left;
 688                         else
 689                                 node = &parent->rb_right;
 690                 }
 691                 rb_link_node(&e->rb_node, parent, node);
 692                 rb_insert_color(&e->rb_node, &wc->freetree);
 693         } else {
 694                 list_add_tail(&e->lru, &wc->freelist);
 695         }
 696         wc->freelist_size++;
 697 }
 698
 699 static inline void writecache_verify_watermark(struct dm_writecache *wc)
 700 {
 701         if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
 702                 queue_work(wc->writeback_wq, &wc->writeback_work);
 703 }
 704
 705 static void writecache_max_age_timer(struct timer_list *t)
 706 {
 707         struct dm_writecache *wc = from_timer(wc, t, max_age_timer);
 708
 709         if (!dm_suspended(wc->ti) && !writecache_has_error(wc)) {
 710                 queue_work(wc->writeback_wq, &wc->writeback_work);
 711                 mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
 712         }
 713 }
 714
 715 static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc, sector_t expected_sector)
 716 {
 717         struct wc_entry *e;
 718
 719         if (WC_MODE_SORT_FREELIST(wc)) {
 720                 struct rb_node *next;
 721                 if (unlikely(!wc->current_free))
 722                         return NULL;
 723                 e = wc->current_free;
 724                 if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
 725                         return NULL;
 726                 next = rb_next(&e->rb_node);
 727                 rb_erase(&e->rb_node, &wc->freetree);
 728                 if (unlikely(!next))
 729                         next = rb_first(&wc->freetree);
 730                 wc->current_free = next ? container_of(next, struct wc_entry, rb_node) : NULL;
 731         } else {
 732                 if (unlikely(list_empty(&wc->freelist)))
 733                         return NULL;
 734                 e = container_of(wc->freelist.next, struct wc_entry, lru);
 735                 if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
 736                         return NULL;
 737                 list_del(&e->lru);
 738         }
 739         wc->freelist_size--;
 740
 741         writecache_verify_watermark(wc);
 742
 743         return e;
 744 }
 745
 746 static void writecache_free_entry(struct dm_writecache *wc, struct wc_entry *e)
 747 {
 748         writecache_unlink(wc, e);
 749         writecache_add_to_freelist(wc, e);
 750         clear_seq_count(wc, e);
 751         writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
 752         if (unlikely(waitqueue_active(&wc->freelist_wait)))
 753                 wake_up(&wc->freelist_wait);
 754 }
 755
 756 static void writecache_wait_on_freelist(struct dm_writecache *wc)
 757 {
 758         DEFINE_WAIT(wait);
 759
 760         prepare_to_wait(&wc->freelist_wait, &wait, TASK_UNINTERRUPTIBLE);
 761         wc_unlock(wc);
 762         io_schedule();
 763         finish_wait(&wc->freelist_wait, &wait);
 764         wc_lock(wc);
 765 }
 766
 767 static void writecache_poison_lists(struct dm_writecache *wc)
 768 {
 769         /*
 770          * Catch incorrect access to these values while the device is suspended.
 771          */
 772         memset(&wc->tree, -1, sizeof wc->tree);
 773         wc->lru.next = LIST_POISON1;
 774         wc->lru.prev = LIST_POISON2;
 775         wc->freelist.next = LIST_POISON1;
 776         wc->freelist.prev = LIST_POISON2;
 777 }
 778
 779 static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
 780 {
 781         writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
 782         if (WC_MODE_PMEM(wc))
 783                 writecache_flush_region(wc, memory_data(wc, e), wc->block_size);
 784 }
 785
 786 static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
 787 {
 788         return read_seq_count(wc, e) < wc->seq_count;
 789 }
 790
 791 static void writecache_flush(struct dm_writecache *wc)
 792 {
 793         struct wc_entry *e, *e2;
 794         bool need_flush_after_free;
 795
 796         wc->uncommitted_blocks = 0;
 797         del_timer(&wc->autocommit_timer);
 798
 799         if (list_empty(&wc->lru))
 800                 return;
 801
 802         e = container_of(wc->lru.next, struct wc_entry, lru);
 803         if (writecache_entry_is_committed(wc, e)) {
 804                 if (wc->overwrote_committed) {
 805                         writecache_wait_for_ios(wc, WRITE);
 806                         writecache_disk_flush(wc, wc->ssd_dev);
 807                         wc->overwrote_committed = false;
 808                 }
 809                 return;
 810         }
 811         while (1) {
 812                 writecache_flush_entry(wc, e);
 813                 if (unlikely(e->lru.next == &wc->lru))
 814                         break;
 815                 e2 = container_of(e->lru.next, struct wc_entry, lru);
 816                 if (writecache_entry_is_committed(wc, e2))
 817                         break;
 818                 e = e2;
 819                 cond_resched();
 820         }
 821         writecache_commit_flushed(wc, true);
 822
 823         wc->seq_count++;
 824         pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
 825         if (WC_MODE_PMEM(wc))
 826                 writecache_commit_flushed(wc, false);
 827         else
 828                 ssd_commit_superblock(wc);
 829
 830         wc->overwrote_committed = false;
 831
 832         need_flush_after_free = false;
 833         while (1) {
 834                 /* Free another committed entry with lower seq-count */
 835                 struct rb_node *rb_node = rb_prev(&e->rb_node);
 836
 837                 if (rb_node) {
 838                         e2 = container_of(rb_node, struct wc_entry, rb_node);
 839                         if (read_original_sector(wc, e2) == read_original_sector(wc, e) &&
 840                             likely(!e2->write_in_progress)) {
 841                                 writecache_free_entry(wc, e2);
 842                                 need_flush_after_free = true;
 843                         }
 844                 }
 845                 if (unlikely(e->lru.prev == &wc->lru))
 846                         break;
 847                 e = container_of(e->lru.prev, struct wc_entry, lru);
 848                 cond_resched();
 849         }
 850
 851         if (need_flush_after_free)
 852                 writecache_commit_flushed(wc, false);
 853 }
 854
 855 static void writecache_flush_work(struct work_struct *work)
 856 {
 857         struct dm_writecache *wc = container_of(work, struct dm_writecache, flush_work);
 858
 859         wc_lock(wc);
 860         writecache_flush(wc);
 861         wc_unlock(wc);
 862 }
 863
 864 static void writecache_autocommit_timer(struct timer_list *t)
 865 {
 866         struct dm_writecache *wc = from_timer(wc, t, autocommit_timer);
 867         if (!writecache_has_error(wc))
 868                 queue_work(wc->writeback_wq, &wc->flush_work);
 869 }
 870
 871 static void writecache_schedule_autocommit(struct dm_writecache *wc)
 872 {
 873         if (!timer_pending(&wc->autocommit_timer))
 874                 mod_timer(&wc->autocommit_timer, jiffies + wc->autocommit_jiffies);
 875 }
 876
 877 static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_t end)
 878 {
 879         struct wc_entry *e;
 880         bool discarded_something = false;
 881
 882         e = writecache_find_entry(wc, start, WFE_RETURN_FOLLOWING | WFE_LOWEST_SEQ);
 883         if (unlikely(!e))
 884                 return;
 885
 886         while (read_original_sector(wc, e) < end) {
 887                 struct rb_node *node = rb_next(&e->rb_node);
 888
 889                 if (likely(!e->write_in_progress)) {
 890                         if (!discarded_something) {
 891                                 if (!WC_MODE_PMEM(wc)) {
 892                                         writecache_wait_for_ios(wc, READ);
 893                                         writecache_wait_for_ios(wc, WRITE);
 894                                 }
 895                                 discarded_something = true;
 896                         }
 897                         if (!writecache_entry_is_committed(wc, e))
 898                                 wc->uncommitted_blocks--;
 899                         writecache_free_entry(wc, e);
 900                 }
 901
 902                 if (unlikely(!node))
 903                         break;
 904
 905                 e = container_of(node, struct wc_entry, rb_node);
 906         }
 907
 908         if (discarded_something)
 909                 writecache_commit_flushed(wc, false);
 910 }
 911
 912 static bool writecache_wait_for_writeback(struct dm_writecache *wc)
 913 {
 914         if (wc->writeback_size) {
 915                 writecache_wait_on_freelist(wc);
 916                 return true;
 917         }
 918         return false;
 919 }
 920
 921 static void writecache_suspend(struct dm_target *ti)
 922 {
 923         struct dm_writecache *wc = ti->private;
 924         bool flush_on_suspend;
 925
 926         del_timer_sync(&wc->autocommit_timer);
 927         del_timer_sync(&wc->max_age_timer);
 928
 929         wc_lock(wc);
 930         writecache_flush(wc);
 931         flush_on_suspend = wc->flush_on_suspend;
 932         if (flush_on_suspend) {
 933                 wc->flush_on_suspend = false;
 934                 wc->writeback_all++;
 935                 queue_work(wc->writeback_wq, &wc->writeback_work);
 936         }
 937         wc_unlock(wc);
 938
 939         drain_workqueue(wc->writeback_wq);
 940
 941         wc_lock(wc);
 942         if (flush_on_suspend)
 943                 wc->writeback_all--;
 944         while (writecache_wait_for_writeback(wc));
 945
 946         if (WC_MODE_PMEM(wc))
 947                 persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
 948
 949         writecache_poison_lists(wc);
 950
 951         wc_unlock(wc);
 952 }
 953
 954 static int writecache_alloc_entries(struct dm_writecache *wc)
 955 {
 956         size_t b;
 957
 958         if (wc->entries)
 959                 return 0;
 960         wc->entries = vmalloc(array_size(sizeof(struct wc_entry), wc->n_blocks));
 961         if (!wc->entries)
 962                 return -ENOMEM;
 963         for (b = 0; b < wc->n_blocks; b++) {
 964                 struct wc_entry *e = &wc->entries[b];
 965                 e->index = b;
 966                 e->write_in_progress = false;
 967                 cond_resched();
 968         }
 969
 970         return 0;
 971 }
 972
 973 static int writecache_read_metadata(struct dm_writecache *wc, sector_t n_sectors)
 974 {
 975         struct dm_io_region region;
 976         struct dm_io_request req;
 977
 978         region.bdev = wc->ssd_dev->bdev;
 979         region.sector = wc->start_sector;
 980         region.count = n_sectors;
 981         req.bi_opf = REQ_OP_READ | REQ_SYNC;
 982         req.mem.type = DM_IO_VMA;
 983         req.mem.ptr.vma = (char *)wc->memory_map;
 984         req.client = wc->dm_io;
 985         req.notify.fn = NULL;
 986
 987         return dm_io(&req, 1, &region, NULL);
 988 }
 989
 990 static void writecache_resume(struct dm_target *ti)
 991 {
 992         struct dm_writecache *wc = ti->private;
 993         size_t b;
 994         bool need_flush = false;
 995         __le64 sb_seq_count;
 996         int r;
 997
 998         wc_lock(wc);
 999
1000         wc->data_device_sectors = bdev_nr_sectors(wc->dev->bdev);
1001
1002         if (WC_MODE_PMEM(wc)) {
1003                 persistent_memory_invalidate_cache(wc->memory_map, wc->memory_map_size);
1004         } else {
1005                 r = writecache_read_metadata(wc, wc->metadata_sectors);
1006                 if (r) {
1007                         size_t sb_entries_offset;
1008                         writecache_error(wc, r, "unable to read metadata: %d", r);
1009                         sb_entries_offset = offsetof(struct wc_memory_superblock, entries);
1010                         memset((char *)wc->memory_map + sb_entries_offset, -1,
1011                                (wc->metadata_sectors << SECTOR_SHIFT) - sb_entries_offset);
1012                 }
1013         }
1014
1015         wc->tree = RB_ROOT;
1016         INIT_LIST_HEAD(&wc->lru);
1017         if (WC_MODE_SORT_FREELIST(wc)) {
1018                 wc->freetree = RB_ROOT;
1019                 wc->current_free = NULL;
1020         } else {
1021                 INIT_LIST_HEAD(&wc->freelist);
1022         }
1023         wc->freelist_size = 0;
1024
1025         r = copy_mc_to_kernel(&sb_seq_count, &sb(wc)->seq_count,
1026                               sizeof(uint64_t));
1027         if (r) {
1028                 writecache_error(wc, r, "hardware memory error when reading superblock: %d", r);
1029                 sb_seq_count = cpu_to_le64(0);
1030         }
1031         wc->seq_count = le64_to_cpu(sb_seq_count);
1032
1033 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
1034         for (b = 0; b < wc->n_blocks; b++) {
1035                 struct wc_entry *e = &wc->entries[b];
1036                 struct wc_memory_entry wme;
1037                 if (writecache_has_error(wc)) {
1038                         e->original_sector = -1;
1039                         e->seq_count = -1;
1040                         continue;
1041                 }
1042                 r = copy_mc_to_kernel(&wme, memory_entry(wc, e),
1043                                       sizeof(struct wc_memory_entry));
1044                 if (r) {
1045                         writecache_error(wc, r, "hardware memory error when reading metadata entry %lu: %d",
1046                                          (unsigned long)b, r);
1047                         e->original_sector = -1;
1048                         e->seq_count = -1;
1049                 } else {
1050                         e->original_sector = le64_to_cpu(wme.original_sector);
1051                         e->seq_count = le64_to_cpu(wme.seq_count);
1052                 }
1053                 cond_resched();
1054         }
1055 #endif
1056         for (b = 0; b < wc->n_blocks; b++) {
1057                 struct wc_entry *e = &wc->entries[b];
1058                 if (!writecache_entry_is_committed(wc, e)) {
1059                         if (read_seq_count(wc, e) != -1) {
1060 erase_this:
1061                                 clear_seq_count(wc, e);
1062                                 need_flush = true;
1063                         }
1064                         writecache_add_to_freelist(wc, e);
1065                 } else {
1066                         struct wc_entry *old;
1067
1068                         old = writecache_find_entry(wc, read_original_sector(wc, e), 0);
1069                         if (!old) {
1070                                 writecache_insert_entry(wc, e);
1071                         } else {
1072                                 if (read_seq_count(wc, old) == read_seq_count(wc, e)) {
1073                                         writecache_error(wc, -EINVAL,
1074                                                  "two identical entries, position %llu, sector %llu, sequence %llu",
1075                                                  (unsigned long long)b, (unsigned long long)read_original_sector(wc, e),
1076                                                  (unsigned long long)read_seq_count(wc, e));
1077                                 }
1078                                 if (read_seq_count(wc, old) > read_seq_count(wc, e)) {
1079                                         goto erase_this;
1080                                 } else {
1081                                         writecache_free_entry(wc, old);
1082                                         writecache_insert_entry(wc, e);
1083                                         need_flush = true;
1084                                 }
1085                         }
1086                 }
1087                 cond_resched();
1088         }
1089
1090         if (need_flush) {
1091                 writecache_flush_all_metadata(wc);
1092                 writecache_commit_flushed(wc, false);
1093         }
1094
1095         writecache_verify_watermark(wc);
1096
1097         if (wc->max_age != MAX_AGE_UNSPECIFIED)
1098                 mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
1099
1100         wc_unlock(wc);
1101 }
1102
1103 static int process_flush_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1104 {
1105         if (argc != 1)
1106                 return -EINVAL;
1107
1108         wc_lock(wc);
1109         if (dm_suspended(wc->ti)) {
1110                 wc_unlock(wc);
1111                 return -EBUSY;
1112         }
1113         if (writecache_has_error(wc)) {
1114                 wc_unlock(wc);
1115                 return -EIO;
1116         }
1117
1118         writecache_flush(wc);
1119         wc->writeback_all++;
1120         queue_work(wc->writeback_wq, &wc->writeback_work);
1121         wc_unlock(wc);
1122
1123         flush_workqueue(wc->writeback_wq);
1124
1125         wc_lock(wc);
1126         wc->writeback_all--;
1127         if (writecache_has_error(wc)) {
1128                 wc_unlock(wc);
1129                 return -EIO;
1130         }
1131         wc_unlock(wc);
1132
1133         return 0;
1134 }
1135
1136 static int process_flush_on_suspend_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1137 {
1138         if (argc != 1)
1139                 return -EINVAL;
1140
1141         wc_lock(wc);
1142         wc->flush_on_suspend = true;
1143         wc_unlock(wc);
1144
1145         return 0;
1146 }
1147
1148 static void activate_cleaner(struct dm_writecache *wc)
1149 {
1150         wc->flush_on_suspend = true;
1151         wc->cleaner = true;
1152         wc->freelist_high_watermark = wc->n_blocks;
1153         wc->freelist_low_watermark = wc->n_blocks;
1154 }
1155
1156 static int process_cleaner_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1157 {
1158         if (argc != 1)
1159                 return -EINVAL;
1160
1161         wc_lock(wc);
1162         activate_cleaner(wc);
1163         if (!dm_suspended(wc->ti))
1164                 writecache_verify_watermark(wc);
1165         wc_unlock(wc);
1166
1167         return 0;
1168 }
1169
1170 static int process_clear_stats_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
1171 {
1172         if (argc != 1)
1173                 return -EINVAL;
1174
1175         wc_lock(wc);
1176         memset(&wc->stats, 0, sizeof wc->stats);
1177         wc_unlock(wc);
1178
1179         return 0;
1180 }
1181
1182 static int writecache_message(struct dm_target *ti, unsigned argc, char **argv,
1183                               char *result, unsigned maxlen)
1184 {
1185         int r = -EINVAL;
1186         struct dm_writecache *wc = ti->private;
1187
1188         if (!strcasecmp(argv[0], "flush"))
1189                 r = process_flush_mesg(argc, argv, wc);
1190         else if (!strcasecmp(argv[0], "flush_on_suspend"))
1191                 r = process_flush_on_suspend_mesg(argc, argv, wc);
1192         else if (!strcasecmp(argv[0], "cleaner"))
1193                 r = process_cleaner_mesg(argc, argv, wc);
1194         else if (!strcasecmp(argv[0], "clear_stats"))
1195                 r = process_clear_stats_mesg(argc, argv, wc);
1196         else
1197                 DMERR("unrecognised message received: %s", argv[0]);
1198
1199         return r;
1200 }
1201
1202 static void memcpy_flushcache_optimized(void *dest, void *source, size_t size)
1203 {
1204         /*
1205          * clflushopt performs better with block size 1024, 2048, 4096
1206          * non-temporal stores perform better with block size 512
1207          *
1208          * block size   512             1024            2048            4096
1209          * movnti       496 MB/s        642 MB/s        725 MB/s        744 MB/s
1210          * clflushopt   373 MB/s        688 MB/s        1.1 GB/s        1.2 GB/s
1211          *
1212          * We see that movnti performs better for 512-byte blocks, and
1213          * clflushopt performs better for 1024-byte and larger blocks. So, we
1214          * prefer clflushopt for sizes >= 768.
1215          *
1216          * NOTE: this happens to be the case now (with dm-writecache's single
1217          * threaded model) but re-evaluate this once memcpy_flushcache() is
1218          * enabled to use movdir64b which might invalidate this performance
1219          * advantage seen with cache-allocating-writes plus flushing.
1220          */
1221 #ifdef CONFIG_X86
1222         if (static_cpu_has(X86_FEATURE_CLFLUSHOPT) &&
1223             likely(boot_cpu_data.x86_clflush_size == 64) &&
1224             likely(size >= 768)) {
1225                 do {
1226                         memcpy((void *)dest, (void *)source, 64);
1227                         clflushopt((void *)dest);
1228                         dest += 64;
1229                         source += 64;
1230                         size -= 64;
1231                 } while (size >= 64);
1232                 return;
1233         }
1234 #endif
1235         memcpy_flushcache(dest, source, size);
1236 }
1237
1238 static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data)
1239 {
1240         void *buf;
1241         unsigned size;
1242         int rw = bio_data_dir(bio);
1243         unsigned remaining_size = wc->block_size;
1244
1245         do {
1246                 struct bio_vec bv = bio_iter_iovec(bio, bio->bi_iter);
1247                 buf = bvec_kmap_local(&bv);
1248                 size = bv.bv_len;
1249                 if (unlikely(size > remaining_size))
1250                         size = remaining_size;
1251
1252                 if (rw == READ) {
1253                         int r;
1254                         r = copy_mc_to_kernel(buf, data, size);
1255                         flush_dcache_page(bio_page(bio));
1256                         if (unlikely(r)) {
1257                                 writecache_error(wc, r, "hardware memory error when reading data: %d", r);
1258                                 bio->bi_status = BLK_STS_IOERR;
1259                         }
1260                 } else {
1261                         flush_dcache_page(bio_page(bio));
1262                         memcpy_flushcache_optimized(data, buf, size);
1263                 }
1264
1265                 kunmap_local(buf);
1266
1267                 data = (char *)data + size;
1268                 remaining_size -= size;
1269                 bio_advance(bio, size);
1270         } while (unlikely(remaining_size));
1271 }
1272
1273 static int writecache_flush_thread(void *data)
1274 {
1275         struct dm_writecache *wc = data;
1276
1277         while (1) {
1278                 struct bio *bio;
1279
1280                 wc_lock(wc);
1281                 bio = bio_list_pop(&wc->flush_list);
1282                 if (!bio) {
1283                         set_current_state(TASK_INTERRUPTIBLE);
1284                         wc_unlock(wc);
1285
1286                         if (unlikely(kthread_should_stop())) {
1287                                 set_current_state(TASK_RUNNING);
1288                                 break;
1289                         }
1290
1291                         schedule();
1292                         continue;
1293                 }
1294
1295                 if (bio_op(bio) == REQ_OP_DISCARD) {
1296                         writecache_discard(wc, bio->bi_iter.bi_sector,
1297                                            bio_end_sector(bio));
1298                         wc_unlock(wc);
1299                         bio_set_dev(bio, wc->dev->bdev);
1300                         submit_bio_noacct(bio);
1301                 } else {
1302                         writecache_flush(wc);
1303                         wc_unlock(wc);
1304                         if (writecache_has_error(wc))
1305                                 bio->bi_status = BLK_STS_IOERR;
1306                         bio_endio(bio);
1307                 }
1308         }
1309
1310         return 0;
1311 }
1312
1313 static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
1314 {
1315         if (bio_list_empty(&wc->flush_list))
1316                 wake_up_process(wc->flush_thread);
1317         bio_list_add(&wc->flush_list, bio);
1318 }
1319
1320 enum wc_map_op {
1321         WC_MAP_SUBMIT,
1322         WC_MAP_REMAP,
1323         WC_MAP_REMAP_ORIGIN,
1324         WC_MAP_RETURN,
1325         WC_MAP_ERROR,
1326 };
1327
1328 static void writecache_map_remap_origin(struct dm_writecache *wc, struct bio *bio,
1329                                         struct wc_entry *e)
1330 {
1331         if (e) {
1332                 sector_t next_boundary =
1333                         read_original_sector(wc, e) - bio->bi_iter.bi_sector;
1334                 if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT)
1335                         dm_accept_partial_bio(bio, next_boundary);
1336         }
1337 }
1338
1339 static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *bio)
1340 {
1341         enum wc_map_op map_op;
1342         struct wc_entry *e;
1343
1344 read_next_block:
1345         wc->stats.reads++;
1346         e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1347         if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
1348                 wc->stats.read_hits++;
1349                 if (WC_MODE_PMEM(wc)) {
1350                         bio_copy_block(wc, bio, memory_data(wc, e));
1351                         if (bio->bi_iter.bi_size)
1352                                 goto read_next_block;
1353                         map_op = WC_MAP_SUBMIT;
1354                 } else {
1355                         dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
1356                         bio_set_dev(bio, wc->ssd_dev->bdev);
1357                         bio->bi_iter.bi_sector = cache_sector(wc, e);
1358                         if (!writecache_entry_is_committed(wc, e))
1359                                 writecache_wait_for_ios(wc, WRITE);
1360                         map_op = WC_MAP_REMAP;
1361                 }
1362         } else {
1363                 writecache_map_remap_origin(wc, bio, e);
1364                 wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1365                 map_op = WC_MAP_REMAP_ORIGIN;
1366         }
1367
1368         return map_op;
1369 }
1370
1371 static void writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
1372                                     struct wc_entry *e, bool search_used)
1373 {
1374         unsigned bio_size = wc->block_size;
1375         sector_t start_cache_sec = cache_sector(wc, e);
1376         sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
1377
1378         while (bio_size < bio->bi_iter.bi_size) {
1379                 if (!search_used) {
1380                         struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
1381                         if (!f)
1382                                 break;
1383                         write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
1384                                                         (bio_size >> SECTOR_SHIFT), wc->seq_count);
1385                         writecache_insert_entry(wc, f);
1386                         wc->uncommitted_blocks++;
1387                 } else {
1388                         struct wc_entry *f;
1389                         struct rb_node *next = rb_next(&e->rb_node);
1390                         if (!next)
1391                                 break;
1392                         f = container_of(next, struct wc_entry, rb_node);
1393                         if (f != e + 1)
1394                                 break;
1395                         if (read_original_sector(wc, f) !=
1396                             read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1397                                 break;
1398                         if (unlikely(f->write_in_progress))
1399                                 break;
1400                         if (writecache_entry_is_committed(wc, f))
1401                                 wc->overwrote_committed = true;
1402                         e = f;
1403                 }
1404                 bio_size += wc->block_size;
1405                 current_cache_sec += wc->block_size >> SECTOR_SHIFT;
1406         }
1407
1408         bio_set_dev(bio, wc->ssd_dev->bdev);
1409         bio->bi_iter.bi_sector = start_cache_sec;
1410         dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
1411
1412         wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1413         wc->stats.writes_allocate += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1414
1415         if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
1416                 wc->uncommitted_blocks = 0;
1417                 queue_work(wc->writeback_wq, &wc->flush_work);
1418         } else {
1419                 writecache_schedule_autocommit(wc);
1420         }
1421 }
1422
1423 static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
1424 {
1425         struct wc_entry *e;
1426
1427         do {
1428                 bool found_entry = false;
1429                 bool search_used = false;
1430                 if (writecache_has_error(wc)) {
1431                         wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1432                         return WC_MAP_ERROR;
1433                 }
1434                 e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
1435                 if (e) {
1436                         if (!writecache_entry_is_committed(wc, e)) {
1437                                 wc->stats.write_hits_uncommitted++;
1438                                 search_used = true;
1439                                 goto bio_copy;
1440                         }
1441                         wc->stats.write_hits_committed++;
1442                         if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
1443                                 wc->overwrote_committed = true;
1444                                 search_used = true;
1445                                 goto bio_copy;
1446                         }
1447                         found_entry = true;
1448                 } else {
1449                         if (unlikely(wc->cleaner) ||
1450                             (wc->metadata_only && !(bio->bi_opf & REQ_META)))
1451                                 goto direct_write;
1452                 }
1453                 e = writecache_pop_from_freelist(wc, (sector_t)-1);
1454                 if (unlikely(!e)) {
1455                         if (!WC_MODE_PMEM(wc) && !found_entry) {
1456 direct_write:
1457                                 e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1458                                 writecache_map_remap_origin(wc, bio, e);
1459                                 wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
1460                                 wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1461                                 return WC_MAP_REMAP_ORIGIN;
1462                         }
1463                         wc->stats.writes_blocked_on_freelist++;
1464                         writecache_wait_on_freelist(wc);
1465                         continue;
1466                 }
1467                 write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
1468                 writecache_insert_entry(wc, e);
1469                 wc->uncommitted_blocks++;
1470                 wc->stats.writes_allocate++;
1471 bio_copy:
1472                 if (WC_MODE_PMEM(wc)) {
1473                         bio_copy_block(wc, bio, memory_data(wc, e));
1474                         wc->stats.writes++;
1475                 } else {
1476                         writecache_bio_copy_ssd(wc, bio, e, search_used);
1477                         return WC_MAP_REMAP;
1478                 }
1479         } while (bio->bi_iter.bi_size);
1480
1481         if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks))
1482                 writecache_flush(wc);
1483         else
1484                 writecache_schedule_autocommit(wc);
1485
1486         return WC_MAP_SUBMIT;
1487 }
1488
1489 static enum wc_map_op writecache_map_flush(struct dm_writecache *wc, struct bio *bio)
1490 {
1491         if (writecache_has_error(wc))
1492                 return WC_MAP_ERROR;
1493
1494         if (WC_MODE_PMEM(wc)) {
1495                 wc->stats.flushes++;
1496                 writecache_flush(wc);
1497                 if (writecache_has_error(wc))
1498                         return WC_MAP_ERROR;
1499                 else if (unlikely(wc->cleaner) || unlikely(wc->metadata_only))
1500                         return WC_MAP_REMAP_ORIGIN;
1501                 return WC_MAP_SUBMIT;
1502         }
1503         /* SSD: */
1504         if (dm_bio_get_target_bio_nr(bio))
1505                 return WC_MAP_REMAP_ORIGIN;
1506         wc->stats.flushes++;
1507         writecache_offload_bio(wc, bio);
1508         return WC_MAP_RETURN;
1509 }
1510
1511 static enum wc_map_op writecache_map_discard(struct dm_writecache *wc, struct bio *bio)
1512 {
1513         wc->stats.discards += bio->bi_iter.bi_size >> wc->block_size_bits;
1514
1515         if (writecache_has_error(wc))
1516                 return WC_MAP_ERROR;
1517
1518         if (WC_MODE_PMEM(wc)) {
1519                 writecache_discard(wc, bio->bi_iter.bi_sector, bio_end_sector(bio));
1520                 return WC_MAP_REMAP_ORIGIN;
1521         }
1522         /* SSD: */
1523         writecache_offload_bio(wc, bio);
1524         return WC_MAP_RETURN;
1525 }
1526
1527 static int writecache_map(struct dm_target *ti, struct bio *bio)
1528 {
1529         struct dm_writecache *wc = ti->private;
1530         enum wc_map_op map_op;
1531
1532         bio->bi_private = NULL;
1533
1534         wc_lock(wc);
1535
1536         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
1537                 map_op = writecache_map_flush(wc, bio);
1538                 goto done;
1539         }
1540
1541         bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
1542
1543         if (unlikely((((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
1544                                 (wc->block_size / 512 - 1)) != 0)) {
1545                 DMERR("I/O is not aligned, sector %llu, size %u, block size %u",
1546                       (unsigned long long)bio->bi_iter.bi_sector,
1547                       bio->bi_iter.bi_size, wc->block_size);
1548                 map_op = WC_MAP_ERROR;
1549                 goto done;
1550         }
1551
1552         if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
1553                 map_op = writecache_map_discard(wc, bio);
1554                 goto done;
1555         }
1556
1557         if (bio_data_dir(bio) == READ)
1558                 map_op = writecache_map_read(wc, bio);
1559         else
1560                 map_op = writecache_map_write(wc, bio);
1561 done:
1562         switch (map_op) {
1563         case WC_MAP_REMAP_ORIGIN:
1564                 if (likely(wc->pause != 0)) {
1565                         if (bio_op(bio) == REQ_OP_WRITE) {
1566                                 dm_iot_io_begin(&wc->iot, 1);
1567                                 bio->bi_private = (void *)2;
1568                         }
1569                 }
1570                 bio_set_dev(bio, wc->dev->bdev);
1571                 wc_unlock(wc);
1572                 return DM_MAPIO_REMAPPED;
1573
1574         case WC_MAP_REMAP:
1575                 /* make sure that writecache_end_io decrements bio_in_progress: */
1576                 bio->bi_private = (void *)1;
1577                 atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
1578                 wc_unlock(wc);
1579                 return DM_MAPIO_REMAPPED;
1580
1581         case WC_MAP_SUBMIT:
1582                 wc_unlock(wc);
1583                 bio_endio(bio);
1584                 return DM_MAPIO_SUBMITTED;
1585
1586         case WC_MAP_RETURN:
1587                 wc_unlock(wc);
1588                 return DM_MAPIO_SUBMITTED;
1589
1590         case WC_MAP_ERROR:
1591                 wc_unlock(wc);
1592                 bio_io_error(bio);
1593                 return DM_MAPIO_SUBMITTED;
1594
1595         default:
1596                 BUG();
1597                 return -1;
1598         }
1599 }
1600
1601 static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status)
1602 {
1603         struct dm_writecache *wc = ti->private;
1604
1605         if (bio->bi_private == (void *)1) {
1606                 int dir = bio_data_dir(bio);
1607                 if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
1608                         if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
1609                                 wake_up(&wc->bio_in_progress_wait[dir]);
1610         } else if (bio->bi_private == (void *)2) {
1611                 dm_iot_io_end(&wc->iot, 1);
1612         }
1613         return 0;
1614 }
1615
1616 static int writecache_iterate_devices(struct dm_target *ti,
1617                                       iterate_devices_callout_fn fn, void *data)
1618 {
1619         struct dm_writecache *wc = ti->private;
1620
1621         return fn(ti, wc->dev, 0, ti->len, data);
1622 }
1623
1624 static void writecache_io_hints(struct dm_target *ti, struct queue_limits *limits)
1625 {
1626         struct dm_writecache *wc = ti->private;
1627
1628         if (limits->logical_block_size < wc->block_size)
1629                 limits->logical_block_size = wc->block_size;
1630
1631         if (limits->physical_block_size < wc->block_size)
1632                 limits->physical_block_size = wc->block_size;
1633
1634         if (limits->io_min < wc->block_size)
1635                 limits->io_min = wc->block_size;
1636 }
1637
1638
1639 static void writecache_writeback_endio(struct bio *bio)
1640 {
1641         struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
1642         struct dm_writecache *wc = wb->wc;
1643         unsigned long flags;
1644
1645         raw_spin_lock_irqsave(&wc->endio_list_lock, flags);
1646         if (unlikely(list_empty(&wc->endio_list)))
1647                 wake_up_process(wc->endio_thread);
1648         list_add_tail(&wb->endio_entry, &wc->endio_list);
1649         raw_spin_unlock_irqrestore(&wc->endio_list_lock, flags);
1650 }
1651
1652 static void writecache_copy_endio(int read_err, unsigned long write_err, void *ptr)
1653 {
1654         struct copy_struct *c = ptr;
1655         struct dm_writecache *wc = c->wc;
1656
1657         c->error = likely(!(read_err | write_err)) ? 0 : -EIO;
1658
1659         raw_spin_lock_irq(&wc->endio_list_lock);
1660         if (unlikely(list_empty(&wc->endio_list)))
1661                 wake_up_process(wc->endio_thread);
1662         list_add_tail(&c->endio_entry, &wc->endio_list);
1663         raw_spin_unlock_irq(&wc->endio_list_lock);
1664 }
1665
1666 static void __writecache_endio_pmem(struct dm_writecache *wc, struct list_head *list)
1667 {
1668         unsigned i;
1669         struct writeback_struct *wb;
1670         struct wc_entry *e;
1671         unsigned long n_walked = 0;
1672
1673         do {
1674                 wb = list_entry(list->next, struct writeback_struct, endio_entry);
1675                 list_del(&wb->endio_entry);
1676
1677                 if (unlikely(wb->bio.bi_status != BLK_STS_OK))
1678                         writecache_error(wc, blk_status_to_errno(wb->bio.bi_status),
1679                                         "write error %d", wb->bio.bi_status);
1680                 i = 0;
1681                 do {
1682                         e = wb->wc_list[i];
1683                         BUG_ON(!e->write_in_progress);
1684                         e->write_in_progress = false;
1685                         INIT_LIST_HEAD(&e->lru);
1686                         if (!writecache_has_error(wc))
1687                                 writecache_free_entry(wc, e);
1688                         BUG_ON(!wc->writeback_size);
1689                         wc->writeback_size--;
1690                         n_walked++;
1691                         if (unlikely(n_walked >= ENDIO_LATENCY)) {
1692                                 writecache_commit_flushed(wc, false);
1693                                 wc_unlock(wc);
1694                                 wc_lock(wc);
1695                                 n_walked = 0;
1696                         }
1697                 } while (++i < wb->wc_list_n);
1698
1699                 if (wb->wc_list != wb->wc_list_inline)
1700                         kfree(wb->wc_list);
1701                 bio_put(&wb->bio);
1702         } while (!list_empty(list));
1703 }
1704
1705 static void __writecache_endio_ssd(struct dm_writecache *wc, struct list_head *list)
1706 {
1707         struct copy_struct *c;
1708         struct wc_entry *e;
1709
1710         do {
1711                 c = list_entry(list->next, struct copy_struct, endio_entry);
1712                 list_del(&c->endio_entry);
1713
1714                 if (unlikely(c->error))
1715                         writecache_error(wc, c->error, "copy error");
1716
1717                 e = c->e;
1718                 do {
1719                         BUG_ON(!e->write_in_progress);
1720                         e->write_in_progress = false;
1721                         INIT_LIST_HEAD(&e->lru);
1722                         if (!writecache_has_error(wc))
1723                                 writecache_free_entry(wc, e);
1724
1725                         BUG_ON(!wc->writeback_size);
1726                         wc->writeback_size--;
1727                         e++;
1728                 } while (--c->n_entries);
1729                 mempool_free(c, &wc->copy_pool);
1730         } while (!list_empty(list));
1731 }
1732
1733 static int writecache_endio_thread(void *data)
1734 {
1735         struct dm_writecache *wc = data;
1736
1737         while (1) {
1738                 struct list_head list;
1739
1740                 raw_spin_lock_irq(&wc->endio_list_lock);
1741                 if (!list_empty(&wc->endio_list))
1742                         goto pop_from_list;
1743                 set_current_state(TASK_INTERRUPTIBLE);
1744                 raw_spin_unlock_irq(&wc->endio_list_lock);
1745
1746                 if (unlikely(kthread_should_stop())) {
1747                         set_current_state(TASK_RUNNING);
1748                         break;
1749                 }
1750
1751                 schedule();
1752
1753                 continue;
1754
1755 pop_from_list:
1756                 list = wc->endio_list;
1757                 list.next->prev = list.prev->next = &list;
1758                 INIT_LIST_HEAD(&wc->endio_list);
1759                 raw_spin_unlock_irq(&wc->endio_list_lock);
1760
1761                 if (!WC_MODE_FUA(wc))
1762                         writecache_disk_flush(wc, wc->dev);
1763
1764                 wc_lock(wc);
1765
1766                 if (WC_MODE_PMEM(wc)) {
1767                         __writecache_endio_pmem(wc, &list);
1768                 } else {
1769                         __writecache_endio_ssd(wc, &list);
1770                         writecache_wait_for_ios(wc, READ);
1771                 }
1772
1773                 writecache_commit_flushed(wc, false);
1774
1775                 wc_unlock(wc);
1776         }
1777
1778         return 0;
1779 }
1780
1781 static bool wc_add_block(struct writeback_struct *wb, struct wc_entry *e)
1782 {
1783         struct dm_writecache *wc = wb->wc;
1784         unsigned block_size = wc->block_size;
1785         void *address = memory_data(wc, e);
1786
1787         persistent_memory_flush_cache(address, block_size);
1788
1789         if (unlikely(bio_end_sector(&wb->bio) >= wc->data_device_sectors))
1790                 return true;
1791
1792         return bio_add_page(&wb->bio, persistent_memory_page(address),
1793                             block_size, persistent_memory_page_offset(address)) != 0;
1794 }
1795
1796 struct writeback_list {
1797         struct list_head list;
1798         size_t size;
1799 };
1800
1801 static void __writeback_throttle(struct dm_writecache *wc, struct writeback_list *wbl)
1802 {
1803         if (unlikely(wc->max_writeback_jobs)) {
1804                 if (READ_ONCE(wc->writeback_size) - wbl->size >= wc->max_writeback_jobs) {
1805                         wc_lock(wc);
1806                         while (wc->writeback_size - wbl->size >= wc->max_writeback_jobs)
1807                                 writecache_wait_on_freelist(wc);
1808                         wc_unlock(wc);
1809                 }
1810         }
1811         cond_resched();
1812 }
1813
1814 static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeback_list *wbl)
1815 {
1816         struct wc_entry *e, *f;
1817         struct bio *bio;
1818         struct writeback_struct *wb;
1819         unsigned max_pages;
1820
1821         while (wbl->size) {
1822                 wbl->size--;
1823                 e = container_of(wbl->list.prev, struct wc_entry, lru);
1824                 list_del(&e->lru);
1825
1826                 max_pages = e->wc_list_contiguous;
1827
1828                 bio = bio_alloc_bioset(wc->dev->bdev, max_pages, REQ_OP_WRITE,
1829                                        GFP_NOIO, &wc->bio_set);
1830                 wb = container_of(bio, struct writeback_struct, bio);
1831                 wb->wc = wc;
1832                 bio->bi_end_io = writecache_writeback_endio;
1833                 bio->bi_iter.bi_sector = read_original_sector(wc, e);
1834                 if (max_pages <= WB_LIST_INLINE ||
1835                     unlikely(!(wb->wc_list = kmalloc_array(max_pages, sizeof(struct wc_entry *),
1836                                                            GFP_NOIO | __GFP_NORETRY |
1837                                                            __GFP_NOMEMALLOC | __GFP_NOWARN)))) {
1838                         wb->wc_list = wb->wc_list_inline;
1839                         max_pages = WB_LIST_INLINE;
1840                 }
1841
1842                 BUG_ON(!wc_add_block(wb, e));
1843
1844                 wb->wc_list[0] = e;
1845                 wb->wc_list_n = 1;
1846
1847                 while (wbl->size && wb->wc_list_n < max_pages) {
1848                         f = container_of(wbl->list.prev, struct wc_entry, lru);
1849                         if (read_original_sector(wc, f) !=
1850                             read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1851                                 break;
1852                         if (!wc_add_block(wb, f))
1853                                 break;
1854                         wbl->size--;
1855                         list_del(&f->lru);
1856                         wb->wc_list[wb->wc_list_n++] = f;
1857                         e = f;
1858                 }
1859                 if (WC_MODE_FUA(wc))
1860                         bio->bi_opf |= REQ_FUA;
1861                 if (writecache_has_error(wc)) {
1862                         bio->bi_status = BLK_STS_IOERR;
1863                         bio_endio(bio);
1864                 } else if (unlikely(!bio_sectors(bio))) {
1865                         bio->bi_status = BLK_STS_OK;
1866                         bio_endio(bio);
1867                 } else {
1868                         submit_bio(bio);
1869                 }
1870
1871                 __writeback_throttle(wc, wbl);
1872         }
1873 }
1874
1875 static void __writecache_writeback_ssd(struct dm_writecache *wc, struct writeback_list *wbl)
1876 {
1877         struct wc_entry *e, *f;
1878         struct dm_io_region from, to;
1879         struct copy_struct *c;
1880
1881         while (wbl->size) {
1882                 unsigned n_sectors;
1883
1884                 wbl->size--;
1885                 e = container_of(wbl->list.prev, struct wc_entry, lru);
1886                 list_del(&e->lru);
1887
1888                 n_sectors = e->wc_list_contiguous << (wc->block_size_bits - SECTOR_SHIFT);
1889
1890                 from.bdev = wc->ssd_dev->bdev;
1891                 from.sector = cache_sector(wc, e);
1892                 from.count = n_sectors;
1893                 to.bdev = wc->dev->bdev;
1894                 to.sector = read_original_sector(wc, e);
1895                 to.count = n_sectors;
1896
1897                 c = mempool_alloc(&wc->copy_pool, GFP_NOIO);
1898                 c->wc = wc;
1899                 c->e = e;
1900                 c->n_entries = e->wc_list_contiguous;
1901
1902                 while ((n_sectors -= wc->block_size >> SECTOR_SHIFT)) {
1903                         wbl->size--;
1904                         f = container_of(wbl->list.prev, struct wc_entry, lru);
1905                         BUG_ON(f != e + 1);
1906                         list_del(&f->lru);
1907                         e = f;
1908                 }
1909
1910                 if (unlikely(to.sector + to.count > wc->data_device_sectors)) {
1911                         if (to.sector >= wc->data_device_sectors) {
1912                                 writecache_copy_endio(0, 0, c);
1913                                 continue;
1914                         }
1915                         from.count = to.count = wc->data_device_sectors - to.sector;
1916                 }
1917
1918                 dm_kcopyd_copy(wc->dm_kcopyd, &from, 1, &to, 0, writecache_copy_endio, c);
1919
1920                 __writeback_throttle(wc, wbl);
1921         }
1922 }
1923
1924 static void writecache_writeback(struct work_struct *work)
1925 {
1926         struct dm_writecache *wc = container_of(work, struct dm_writecache, writeback_work);
1927         struct blk_plug plug;
1928         struct wc_entry *f, *g, *e = NULL;
1929         struct rb_node *node, *next_node;
1930         struct list_head skipped;
1931         struct writeback_list wbl;
1932         unsigned long n_walked;
1933
1934         if (!WC_MODE_PMEM(wc)) {
1935                 /* Wait for any active kcopyd work on behalf of ssd writeback */
1936                 dm_kcopyd_client_flush(wc->dm_kcopyd);
1937         }
1938
1939         if (likely(wc->pause != 0)) {
1940                 while (1) {
1941                         unsigned long idle;
1942                         if (unlikely(wc->cleaner) || unlikely(wc->writeback_all) ||
1943                             unlikely(dm_suspended(wc->ti)))
1944                                 break;
1945                         idle = dm_iot_idle_time(&wc->iot);
1946                         if (idle >= wc->pause)
1947                                 break;
1948                         idle = wc->pause - idle;
1949                         if (idle > HZ)
1950                                 idle = HZ;
1951                         schedule_timeout_idle(idle);
1952                 }
1953         }
1954
1955         wc_lock(wc);
1956 restart:
1957         if (writecache_has_error(wc)) {
1958                 wc_unlock(wc);
1959                 return;
1960         }
1961
1962         if (unlikely(wc->writeback_all)) {
1963                 if (writecache_wait_for_writeback(wc))
1964                         goto restart;
1965         }
1966
1967         if (wc->overwrote_committed) {
1968                 writecache_wait_for_ios(wc, WRITE);
1969         }
1970
1971         n_walked = 0;
1972         INIT_LIST_HEAD(&skipped);
1973         INIT_LIST_HEAD(&wbl.list);
1974         wbl.size = 0;
1975         while (!list_empty(&wc->lru) &&
1976                (wc->writeback_all ||
1977                 wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark ||
1978                 (jiffies - container_of(wc->lru.prev, struct wc_entry, lru)->age >=
1979                  wc->max_age - wc->max_age / MAX_AGE_DIV))) {
1980
1981                 n_walked++;
1982                 if (unlikely(n_walked > WRITEBACK_LATENCY) &&
1983                     likely(!wc->writeback_all)) {
1984                         if (likely(!dm_suspended(wc->ti)))
1985                                 queue_work(wc->writeback_wq, &wc->writeback_work);
1986                         break;
1987                 }
1988
1989                 if (unlikely(wc->writeback_all)) {
1990                         if (unlikely(!e)) {
1991                                 writecache_flush(wc);
1992                                 e = container_of(rb_first(&wc->tree), struct wc_entry, rb_node);
1993                         } else
1994                                 e = g;
1995                 } else
1996                         e = container_of(wc->lru.prev, struct wc_entry, lru);
1997                 BUG_ON(e->write_in_progress);
1998                 if (unlikely(!writecache_entry_is_committed(wc, e))) {
1999                         writecache_flush(wc);
2000                 }
2001                 node = rb_prev(&e->rb_node);
2002                 if (node) {
2003                         f = container_of(node, struct wc_entry, rb_node);
2004                         if (unlikely(read_original_sector(wc, f) ==
2005                                      read_original_sector(wc, e))) {
2006                                 BUG_ON(!f->write_in_progress);
2007                                 list_move(&e->lru, &skipped);
2008                                 cond_resched();
2009                                 continue;
2010                         }
2011                 }
2012                 wc->writeback_size++;
2013                 list_move(&e->lru, &wbl.list);
2014                 wbl.size++;
2015                 e->write_in_progress = true;
2016                 e->wc_list_contiguous = 1;
2017
2018                 f = e;
2019
2020                 while (1) {
2021                         next_node = rb_next(&f->rb_node);
2022                         if (unlikely(!next_node))
2023                                 break;
2024                         g = container_of(next_node, struct wc_entry, rb_node);
2025                         if (unlikely(read_original_sector(wc, g) ==
2026                             read_original_sector(wc, f))) {
2027                                 f = g;
2028                                 continue;
2029                         }
2030                         if (read_original_sector(wc, g) !=
2031                             read_original_sector(wc, f) + (wc->block_size >> SECTOR_SHIFT))
2032                                 break;
2033                         if (unlikely(g->write_in_progress))
2034                                 break;
2035                         if (unlikely(!writecache_entry_is_committed(wc, g)))
2036                                 break;
2037
2038                         if (!WC_MODE_PMEM(wc)) {
2039                                 if (g != f + 1)
2040                                         break;
2041                         }
2042
2043                         n_walked++;
2044                         //if (unlikely(n_walked > WRITEBACK_LATENCY) && likely(!wc->writeback_all))
2045                         //      break;
2046
2047                         wc->writeback_size++;
2048                         list_move(&g->lru, &wbl.list);
2049                         wbl.size++;
2050                         g->write_in_progress = true;
2051                         g->wc_list_contiguous = BIO_MAX_VECS;
2052                         f = g;
2053                         e->wc_list_contiguous++;
2054                         if (unlikely(e->wc_list_contiguous == BIO_MAX_VECS)) {
2055                                 if (unlikely(wc->writeback_all)) {
2056                                         next_node = rb_next(&f->rb_node);
2057                                         if (likely(next_node))
2058                                                 g = container_of(next_node, struct wc_entry, rb_node);
2059                                 }
2060                                 break;
2061                         }
2062                 }
2063                 cond_resched();
2064         }
2065
2066         if (!list_empty(&skipped)) {
2067                 list_splice_tail(&skipped, &wc->lru);
2068                 /*
2069                  * If we didn't do any progress, we must wait until some
2070                  * writeback finishes to avoid burning CPU in a loop
2071                  */
2072                 if (unlikely(!wbl.size))
2073                         writecache_wait_for_writeback(wc);
2074         }
2075
2076         wc_unlock(wc);
2077
2078         blk_start_plug(&plug);
2079
2080         if (WC_MODE_PMEM(wc))
2081                 __writecache_writeback_pmem(wc, &wbl);
2082         else
2083                 __writecache_writeback_ssd(wc, &wbl);
2084
2085         blk_finish_plug(&plug);
2086
2087         if (unlikely(wc->writeback_all)) {
2088                 wc_lock(wc);
2089                 while (writecache_wait_for_writeback(wc));
2090                 wc_unlock(wc);
2091         }
2092 }
2093
2094 static int calculate_memory_size(uint64_t device_size, unsigned block_size,
2095                                  size_t *n_blocks_p, size_t *n_metadata_blocks_p)
2096 {
2097         uint64_t n_blocks, offset;
2098         struct wc_entry e;
2099
2100         n_blocks = device_size;
2101         do_div(n_blocks, block_size + sizeof(struct wc_memory_entry));
2102
2103         while (1) {
2104                 if (!n_blocks)
2105                         return -ENOSPC;
2106                 /* Verify the following entries[n_blocks] won't overflow */
2107                 if (n_blocks >= ((size_t)-sizeof(struct wc_memory_superblock) /
2108                                  sizeof(struct wc_memory_entry)))
2109                         return -EFBIG;
2110                 offset = offsetof(struct wc_memory_superblock, entries[n_blocks]);
2111                 offset = (offset + block_size - 1) & ~(uint64_t)(block_size - 1);
2112                 if (offset + n_blocks * block_size <= device_size)
2113                         break;
2114                 n_blocks--;
2115         }
2116
2117         /* check if the bit field overflows */
2118         e.index = n_blocks;
2119         if (e.index != n_blocks)
2120                 return -EFBIG;
2121
2122         if (n_blocks_p)
2123                 *n_blocks_p = n_blocks;
2124         if (n_metadata_blocks_p)
2125                 *n_metadata_blocks_p = offset >> __ffs(block_size);
2126         return 0;
2127 }
2128
2129 static int init_memory(struct dm_writecache *wc)
2130 {
2131         size_t b;
2132         int r;
2133
2134         r = calculate_memory_size(wc->memory_map_size, wc->block_size, &wc->n_blocks, NULL);
2135         if (r)
2136                 return r;
2137
2138         r = writecache_alloc_entries(wc);
2139         if (r)
2140                 return r;
2141
2142         for (b = 0; b < ARRAY_SIZE(sb(wc)->padding); b++)
2143                 pmem_assign(sb(wc)->padding[b], cpu_to_le64(0));
2144         pmem_assign(sb(wc)->version, cpu_to_le32(MEMORY_SUPERBLOCK_VERSION));
2145         pmem_assign(sb(wc)->block_size, cpu_to_le32(wc->block_size));
2146         pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
2147         pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
2148
2149         for (b = 0; b < wc->n_blocks; b++) {
2150                 write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
2151                 cond_resched();
2152         }
2153
2154         writecache_flush_all_metadata(wc);
2155         writecache_commit_flushed(wc, false);
2156         pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
2157         writecache_flush_region(wc, &sb(wc)->magic, sizeof sb(wc)->magic);
2158         writecache_commit_flushed(wc, false);
2159
2160         return 0;
2161 }
2162
2163 static void writecache_dtr(struct dm_target *ti)
2164 {
2165         struct dm_writecache *wc = ti->private;
2166
2167         if (!wc)
2168                 return;
2169
2170         if (wc->endio_thread)
2171                 kthread_stop(wc->endio_thread);
2172
2173         if (wc->flush_thread)
2174                 kthread_stop(wc->flush_thread);
2175
2176         bioset_exit(&wc->bio_set);
2177
2178         mempool_exit(&wc->copy_pool);
2179
2180         if (wc->writeback_wq)
2181                 destroy_workqueue(wc->writeback_wq);
2182
2183         if (wc->dev)
2184                 dm_put_device(ti, wc->dev);
2185
2186         if (wc->ssd_dev)
2187                 dm_put_device(ti, wc->ssd_dev);
2188
2189         vfree(wc->entries);
2190
2191         if (wc->memory_map) {
2192                 if (WC_MODE_PMEM(wc))
2193                         persistent_memory_release(wc);
2194                 else
2195                         vfree(wc->memory_map);
2196         }
2197
2198         if (wc->dm_kcopyd)
2199                 dm_kcopyd_client_destroy(wc->dm_kcopyd);
2200
2201         if (wc->dm_io)
2202                 dm_io_client_destroy(wc->dm_io);
2203
2204         vfree(wc->dirty_bitmap);
2205
2206         kfree(wc);
2207 }
2208
2209 static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
2210 {
2211         struct dm_writecache *wc;
2212         struct dm_arg_set as;
2213         const char *string;
2214         unsigned opt_params;
2215         size_t offset, data_size;
2216         int i, r;
2217         char dummy;
2218         int high_wm_percent = HIGH_WATERMARK;
2219         int low_wm_percent = LOW_WATERMARK;
2220         uint64_t x;
2221         struct wc_memory_superblock s;
2222
2223         static struct dm_arg _args[] = {
2224                 {0, 18, "Invalid number of feature args"},
2225         };
2226
2227         as.argc = argc;
2228         as.argv = argv;
2229
2230         wc = kzalloc(sizeof(struct dm_writecache), GFP_KERNEL);
2231         if (!wc) {
2232                 ti->error = "Cannot allocate writecache structure";
2233                 r = -ENOMEM;
2234                 goto bad;
2235         }
2236         ti->private = wc;
2237         wc->ti = ti;
2238
2239         mutex_init(&wc->lock);
2240         wc->max_age = MAX_AGE_UNSPECIFIED;
2241         writecache_poison_lists(wc);
2242         init_waitqueue_head(&wc->freelist_wait);
2243         timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0);
2244         timer_setup(&wc->max_age_timer, writecache_max_age_timer, 0);
2245
2246         for (i = 0; i < 2; i++) {
2247                 atomic_set(&wc->bio_in_progress[i], 0);
2248                 init_waitqueue_head(&wc->bio_in_progress_wait[i]);
2249         }
2250
2251         wc->dm_io = dm_io_client_create();
2252         if (IS_ERR(wc->dm_io)) {
2253                 r = PTR_ERR(wc->dm_io);
2254                 ti->error = "Unable to allocate dm-io client";
2255                 wc->dm_io = NULL;
2256                 goto bad;
2257         }
2258
2259         wc->writeback_wq = alloc_workqueue("writecache-writeback", WQ_MEM_RECLAIM, 1);
2260         if (!wc->writeback_wq) {
2261                 r = -ENOMEM;
2262                 ti->error = "Could not allocate writeback workqueue";
2263                 goto bad;
2264         }
2265         INIT_WORK(&wc->writeback_work, writecache_writeback);
2266         INIT_WORK(&wc->flush_work, writecache_flush_work);
2267
2268         dm_iot_init(&wc->iot);
2269
2270         raw_spin_lock_init(&wc->endio_list_lock);
2271         INIT_LIST_HEAD(&wc->endio_list);
2272         wc->endio_thread = kthread_run(writecache_endio_thread, wc, "writecache_endio");
2273         if (IS_ERR(wc->endio_thread)) {
2274                 r = PTR_ERR(wc->endio_thread);
2275                 wc->endio_thread = NULL;
2276                 ti->error = "Couldn't spawn endio thread";
2277                 goto bad;
2278         }
2279
2280         /*
2281          * Parse the mode (pmem or ssd)
2282          */
2283         string = dm_shift_arg(&as);
2284         if (!string)
2285                 goto bad_arguments;
2286
2287         if (!strcasecmp(string, "s")) {
2288                 wc->pmem_mode = false;
2289         } else if (!strcasecmp(string, "p")) {
2290 #ifdef DM_WRITECACHE_HAS_PMEM
2291                 wc->pmem_mode = true;
2292                 wc->writeback_fua = true;
2293 #else
2294                 /*
2295                  * If the architecture doesn't support persistent memory or
2296                  * the kernel doesn't support any DAX drivers, this driver can
2297                  * only be used in SSD-only mode.
2298                  */
2299                 r = -EOPNOTSUPP;
2300                 ti->error = "Persistent memory or DAX not supported on this system";
2301                 goto bad;
2302 #endif
2303         } else {
2304                 goto bad_arguments;
2305         }
2306
2307         if (WC_MODE_PMEM(wc)) {
2308                 r = bioset_init(&wc->bio_set, BIO_POOL_SIZE,
2309                                 offsetof(struct writeback_struct, bio),
2310                                 BIOSET_NEED_BVECS);
2311                 if (r) {
2312                         ti->error = "Could not allocate bio set";
2313                         goto bad;
2314                 }
2315         } else {
2316                 wc->pause = PAUSE_WRITEBACK;
2317                 r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
2318                 if (r) {
2319                         ti->error = "Could not allocate mempool";
2320                         goto bad;
2321                 }
2322         }
2323
2324         /*
2325          * Parse the origin data device
2326          */
2327         string = dm_shift_arg(&as);
2328         if (!string)
2329                 goto bad_arguments;
2330         r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->dev);
2331         if (r) {
2332                 ti->error = "Origin data device lookup failed";
2333                 goto bad;
2334         }
2335
2336         /*
2337          * Parse cache data device (be it pmem or ssd)
2338          */
2339         string = dm_shift_arg(&as);
2340         if (!string)
2341                 goto bad_arguments;
2342
2343         r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->ssd_dev);
2344         if (r) {
2345                 ti->error = "Cache data device lookup failed";
2346                 goto bad;
2347         }
2348         wc->memory_map_size = bdev_nr_bytes(wc->ssd_dev->bdev);
2349
2350         /*
2351          * Parse the cache block size
2352          */
2353         string = dm_shift_arg(&as);
2354         if (!string)
2355                 goto bad_arguments;
2356         if (sscanf(string, "%u%c", &wc->block_size, &dummy) != 1 ||
2357             wc->block_size < 512 || wc->block_size > PAGE_SIZE ||
2358             (wc->block_size & (wc->block_size - 1))) {
2359                 r = -EINVAL;
2360                 ti->error = "Invalid block size";
2361                 goto bad;
2362         }
2363         if (wc->block_size < bdev_logical_block_size(wc->dev->bdev) ||
2364             wc->block_size < bdev_logical_block_size(wc->ssd_dev->bdev)) {
2365                 r = -EINVAL;
2366                 ti->error = "Block size is smaller than device logical block size";
2367                 goto bad;
2368         }
2369         wc->block_size_bits = __ffs(wc->block_size);
2370
2371         wc->max_writeback_jobs = MAX_WRITEBACK_JOBS;
2372         wc->autocommit_blocks = !WC_MODE_PMEM(wc) ? AUTOCOMMIT_BLOCKS_SSD : AUTOCOMMIT_BLOCKS_PMEM;
2373         wc->autocommit_jiffies = msecs_to_jiffies(AUTOCOMMIT_MSEC);
2374
2375         /*
2376          * Parse optional arguments
2377          */
2378         r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
2379         if (r)
2380                 goto bad;
2381
2382         while (opt_params) {
2383                 string = dm_shift_arg(&as), opt_params--;
2384                 if (!strcasecmp(string, "start_sector") && opt_params >= 1) {
2385                         unsigned long long start_sector;
2386                         string = dm_shift_arg(&as), opt_params--;
2387                         if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
2388                                 goto invalid_optional;
2389                         wc->start_sector = start_sector;
2390                         wc->start_sector_set = true;
2391                         if (wc->start_sector != start_sector ||
2392                             wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
2393                                 goto invalid_optional;
2394                 } else if (!strcasecmp(string, "high_watermark") && opt_params >= 1) {
2395                         string = dm_shift_arg(&as), opt_params--;
2396                         if (sscanf(string, "%d%c", &high_wm_percent, &dummy) != 1)
2397                                 goto invalid_optional;
2398                         if (high_wm_percent < 0 || high_wm_percent > 100)
2399                                 goto invalid_optional;
2400                         wc->high_wm_percent_value = high_wm_percent;
2401                         wc->high_wm_percent_set = true;
2402                 } else if (!strcasecmp(string, "low_watermark") && opt_params >= 1) {
2403                         string = dm_shift_arg(&as), opt_params--;
2404                         if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
2405                                 goto invalid_optional;
2406                         if (low_wm_percent < 0 || low_wm_percent > 100)
2407                                 goto invalid_optional;
2408                         wc->low_wm_percent_value = low_wm_percent;
2409                         wc->low_wm_percent_set = true;
2410                 } else if (!strcasecmp(string, "writeback_jobs") && opt_params >= 1) {
2411                         string = dm_shift_arg(&as), opt_params--;
2412                         if (sscanf(string, "%u%c", &wc->max_writeback_jobs, &dummy) != 1)
2413                                 goto invalid_optional;
2414                         wc->max_writeback_jobs_set = true;
2415                 } else if (!strcasecmp(string, "autocommit_blocks") && opt_params >= 1) {
2416                         string = dm_shift_arg(&as), opt_params--;
2417                         if (sscanf(string, "%u%c", &wc->autocommit_blocks, &dummy) != 1)
2418                                 goto invalid_optional;
2419                         wc->autocommit_blocks_set = true;
2420                 } else if (!strcasecmp(string, "autocommit_time") && opt_params >= 1) {
2421                         unsigned autocommit_msecs;
2422                         string = dm_shift_arg(&as), opt_params--;
2423                         if (sscanf(string, "%u%c", &autocommit_msecs, &dummy) != 1)
2424                                 goto invalid_optional;
2425                         if (autocommit_msecs > 3600000)
2426                                 goto invalid_optional;
2427                         wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs);
2428                         wc->autocommit_time_value = autocommit_msecs;
2429                         wc->autocommit_time_set = true;
2430                 } else if (!strcasecmp(string, "max_age") && opt_params >= 1) {
2431                         unsigned max_age_msecs;
2432                         string = dm_shift_arg(&as), opt_params--;
2433                         if (sscanf(string, "%u%c", &max_age_msecs, &dummy) != 1)
2434                                 goto invalid_optional;
2435                         if (max_age_msecs > 86400000)
2436                                 goto invalid_optional;
2437                         wc->max_age = msecs_to_jiffies(max_age_msecs);
2438                         wc->max_age_set = true;
2439                         wc->max_age_value = max_age_msecs;
2440                 } else if (!strcasecmp(string, "cleaner")) {
2441                         wc->cleaner_set = true;
2442                         wc->cleaner = true;
2443                 } else if (!strcasecmp(string, "fua")) {
2444                         if (WC_MODE_PMEM(wc)) {
2445                                 wc->writeback_fua = true;
2446                                 wc->writeback_fua_set = true;
2447                         } else goto invalid_optional;
2448                 } else if (!strcasecmp(string, "nofua")) {
2449                         if (WC_MODE_PMEM(wc)) {
2450                                 wc->writeback_fua = false;
2451                                 wc->writeback_fua_set = true;
2452                         } else goto invalid_optional;
2453                 } else if (!strcasecmp(string, "metadata_only")) {
2454                         wc->metadata_only = true;
2455                 } else if (!strcasecmp(string, "pause_writeback") && opt_params >= 1) {
2456                         unsigned pause_msecs;
2457                         if (WC_MODE_PMEM(wc))
2458                                 goto invalid_optional;
2459                         string = dm_shift_arg(&as), opt_params--;
2460                         if (sscanf(string, "%u%c", &pause_msecs, &dummy) != 1)
2461                                 goto invalid_optional;
2462                         if (pause_msecs > 60000)
2463                                 goto invalid_optional;
2464                         wc->pause = msecs_to_jiffies(pause_msecs);
2465                         wc->pause_set = true;
2466                         wc->pause_value = pause_msecs;
2467                 } else {
2468 invalid_optional:
2469                         r = -EINVAL;
2470                         ti->error = "Invalid optional argument";
2471                         goto bad;
2472                 }
2473         }
2474
2475         if (high_wm_percent < low_wm_percent) {
2476                 r = -EINVAL;
2477                 ti->error = "High watermark must be greater than or equal to low watermark";
2478                 goto bad;
2479         }
2480
2481         if (WC_MODE_PMEM(wc)) {
2482                 if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
2483                         r = -EOPNOTSUPP;
2484                         ti->error = "Asynchronous persistent memory not supported as pmem cache";
2485                         goto bad;
2486                 }
2487
2488                 r = persistent_memory_claim(wc);
2489                 if (r) {
2490                         ti->error = "Unable to map persistent memory for cache";
2491                         goto bad;
2492                 }
2493         } else {
2494                 size_t n_blocks, n_metadata_blocks;
2495                 uint64_t n_bitmap_bits;
2496
2497                 wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
2498
2499                 bio_list_init(&wc->flush_list);
2500                 wc->flush_thread = kthread_run(writecache_flush_thread, wc, "dm_writecache_flush");
2501                 if (IS_ERR(wc->flush_thread)) {
2502                         r = PTR_ERR(wc->flush_thread);
2503                         wc->flush_thread = NULL;
2504                         ti->error = "Couldn't spawn flush thread";
2505                         goto bad;
2506                 }
2507
2508                 r = calculate_memory_size(wc->memory_map_size, wc->block_size,
2509                                           &n_blocks, &n_metadata_blocks);
2510                 if (r) {
2511                         ti->error = "Invalid device size";
2512                         goto bad;
2513                 }
2514
2515                 n_bitmap_bits = (((uint64_t)n_metadata_blocks << wc->block_size_bits) +
2516                                  BITMAP_GRANULARITY - 1) / BITMAP_GRANULARITY;
2517                 /* this is limitation of test_bit functions */
2518                 if (n_bitmap_bits > 1U << 31) {
2519                         r = -EFBIG;
2520                         ti->error = "Invalid device size";
2521                         goto bad;
2522                 }
2523
2524                 wc->memory_map = vmalloc(n_metadata_blocks << wc->block_size_bits);
2525                 if (!wc->memory_map) {
2526                         r = -ENOMEM;
2527                         ti->error = "Unable to allocate memory for metadata";
2528                         goto bad;
2529                 }
2530
2531                 wc->dm_kcopyd = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2532                 if (IS_ERR(wc->dm_kcopyd)) {
2533                         r = PTR_ERR(wc->dm_kcopyd);
2534                         ti->error = "Unable to allocate dm-kcopyd client";
2535                         wc->dm_kcopyd = NULL;
2536                         goto bad;
2537                 }
2538
2539                 wc->metadata_sectors = n_metadata_blocks << (wc->block_size_bits - SECTOR_SHIFT);
2540                 wc->dirty_bitmap_size = (n_bitmap_bits + BITS_PER_LONG - 1) /
2541                         BITS_PER_LONG * sizeof(unsigned long);
2542                 wc->dirty_bitmap = vzalloc(wc->dirty_bitmap_size);
2543                 if (!wc->dirty_bitmap) {
2544                         r = -ENOMEM;
2545                         ti->error = "Unable to allocate dirty bitmap";
2546                         goto bad;
2547                 }
2548
2549                 r = writecache_read_metadata(wc, wc->block_size >> SECTOR_SHIFT);
2550                 if (r) {
2551                         ti->error = "Unable to read first block of metadata";
2552                         goto bad;
2553                 }
2554         }
2555
2556         r = copy_mc_to_kernel(&s, sb(wc), sizeof(struct wc_memory_superblock));
2557         if (r) {
2558                 ti->error = "Hardware memory error when reading superblock";
2559                 goto bad;
2560         }
2561         if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
2562                 r = init_memory(wc);
2563                 if (r) {
2564                         ti->error = "Unable to initialize device";
2565                         goto bad;
2566                 }
2567                 r = copy_mc_to_kernel(&s, sb(wc),
2568                                       sizeof(struct wc_memory_superblock));
2569                 if (r) {
2570                         ti->error = "Hardware memory error when reading superblock";
2571                         goto bad;
2572                 }
2573         }
2574
2575         if (le32_to_cpu(s.magic) != MEMORY_SUPERBLOCK_MAGIC) {
2576                 ti->error = "Invalid magic in the superblock";
2577                 r = -EINVAL;
2578                 goto bad;
2579         }
2580
2581         if (le32_to_cpu(s.version) != MEMORY_SUPERBLOCK_VERSION) {
2582                 ti->error = "Invalid version in the superblock";
2583                 r = -EINVAL;
2584                 goto bad;
2585         }
2586
2587         if (le32_to_cpu(s.block_size) != wc->block_size) {
2588                 ti->error = "Block size does not match superblock";
2589                 r = -EINVAL;
2590                 goto bad;
2591         }
2592
2593         wc->n_blocks = le64_to_cpu(s.n_blocks);
2594
2595         offset = wc->n_blocks * sizeof(struct wc_memory_entry);
2596         if (offset / sizeof(struct wc_memory_entry) != le64_to_cpu(sb(wc)->n_blocks)) {
2597 overflow:
2598                 ti->error = "Overflow in size calculation";
2599                 r = -EINVAL;
2600                 goto bad;
2601         }
2602         offset += sizeof(struct wc_memory_superblock);
2603         if (offset < sizeof(struct wc_memory_superblock))
2604                 goto overflow;
2605         offset = (offset + wc->block_size - 1) & ~(size_t)(wc->block_size - 1);
2606         data_size = wc->n_blocks * (size_t)wc->block_size;
2607         if (!offset || (data_size / wc->block_size != wc->n_blocks) ||
2608             (offset + data_size < offset))
2609                 goto overflow;
2610         if (offset + data_size > wc->memory_map_size) {
2611                 ti->error = "Memory area is too small";
2612                 r = -EINVAL;
2613                 goto bad;
2614         }
2615
2616         wc->metadata_sectors = offset >> SECTOR_SHIFT;
2617         wc->block_start = (char *)sb(wc) + offset;
2618
2619         x = (uint64_t)wc->n_blocks * (100 - high_wm_percent);
2620         x += 50;
2621         do_div(x, 100);
2622         wc->freelist_high_watermark = x;
2623         x = (uint64_t)wc->n_blocks * (100 - low_wm_percent);
2624         x += 50;
2625         do_div(x, 100);
2626         wc->freelist_low_watermark = x;
2627
2628         if (wc->cleaner)
2629                 activate_cleaner(wc);
2630
2631         r = writecache_alloc_entries(wc);
2632         if (r) {
2633                 ti->error = "Cannot allocate memory";
2634                 goto bad;
2635         }
2636
2637         ti->num_flush_bios = WC_MODE_PMEM(wc) ? 1 : 2;
2638         ti->flush_supported = true;
2639         ti->num_discard_bios = 1;
2640
2641         if (WC_MODE_PMEM(wc))
2642                 persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
2643
2644         return 0;
2645
2646 bad_arguments:
2647         r = -EINVAL;
2648         ti->error = "Bad arguments";
2649 bad:
2650         writecache_dtr(ti);
2651         return r;
2652 }
2653
2654 static void writecache_status(struct dm_target *ti, status_type_t type,
2655                               unsigned status_flags, char *result, unsigned maxlen)
2656 {
2657         struct dm_writecache *wc = ti->private;
2658         unsigned extra_args;
2659         unsigned sz = 0;
2660
2661         switch (type) {
2662         case STATUSTYPE_INFO:
2663                 DMEMIT("%ld %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu",
2664                        writecache_has_error(wc),
2665                        (unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
2666                        (unsigned long long)wc->writeback_size,
2667                        wc->stats.reads,
2668                        wc->stats.read_hits,
2669                        wc->stats.writes,
2670                        wc->stats.write_hits_uncommitted,
2671                        wc->stats.write_hits_committed,
2672                        wc->stats.writes_around,
2673                        wc->stats.writes_allocate,
2674                        wc->stats.writes_blocked_on_freelist,
2675                        wc->stats.flushes,
2676                        wc->stats.discards);
2677                 break;
2678         case STATUSTYPE_TABLE:
2679                 DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
2680                                 wc->dev->name, wc->ssd_dev->name, wc->block_size);
2681                 extra_args = 0;
2682                 if (wc->start_sector_set)
2683                         extra_args += 2;
2684                 if (wc->high_wm_percent_set)
2685                         extra_args += 2;
2686                 if (wc->low_wm_percent_set)
2687                         extra_args += 2;
2688                 if (wc->max_writeback_jobs_set)
2689                         extra_args += 2;
2690                 if (wc->autocommit_blocks_set)
2691                         extra_args += 2;
2692                 if (wc->autocommit_time_set)
2693                         extra_args += 2;
2694                 if (wc->max_age_set)
2695                         extra_args += 2;
2696                 if (wc->cleaner_set)
2697                         extra_args++;
2698                 if (wc->writeback_fua_set)
2699                         extra_args++;
2700                 if (wc->metadata_only)
2701                         extra_args++;
2702                 if (wc->pause_set)
2703                         extra_args += 2;
2704
2705                 DMEMIT("%u", extra_args);
2706                 if (wc->start_sector_set)
2707                         DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
2708                 if (wc->high_wm_percent_set)
2709                         DMEMIT(" high_watermark %u", wc->high_wm_percent_value);
2710                 if (wc->low_wm_percent_set)
2711                         DMEMIT(" low_watermark %u", wc->low_wm_percent_value);
2712                 if (wc->max_writeback_jobs_set)
2713                         DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
2714                 if (wc->autocommit_blocks_set)
2715                         DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
2716                 if (wc->autocommit_time_set)
2717                         DMEMIT(" autocommit_time %u", wc->autocommit_time_value);
2718                 if (wc->max_age_set)
2719                         DMEMIT(" max_age %u", wc->max_age_value);
2720                 if (wc->cleaner_set)
2721                         DMEMIT(" cleaner");
2722                 if (wc->writeback_fua_set)
2723                         DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
2724                 if (wc->metadata_only)
2725                         DMEMIT(" metadata_only");
2726                 if (wc->pause_set)
2727                         DMEMIT(" pause_writeback %u", wc->pause_value);
2728                 break;
2729         case STATUSTYPE_IMA:
2730                 *result = '\0';
2731                 break;
2732         }
2733 }
2734
2735 static struct target_type writecache_target = {
2736         .name                   = "writecache",
2737         .version                = {1, 6, 0},
2738         .module                 = THIS_MODULE,
2739         .ctr                    = writecache_ctr,
2740         .dtr                    = writecache_dtr,
2741         .status                 = writecache_status,
2742         .postsuspend            = writecache_suspend,
2743         .resume                 = writecache_resume,
2744         .message                = writecache_message,
2745         .map                    = writecache_map,
2746         .end_io                 = writecache_end_io,
2747         .iterate_devices        = writecache_iterate_devices,
2748         .io_hints               = writecache_io_hints,
2749 };
2750
2751 static int __init dm_writecache_init(void)
2752 {
2753         int r;
2754
2755         r = dm_register_target(&writecache_target);
2756         if (r < 0) {
2757                 DMERR("register failed %d", r);
2758                 return r;
2759         }
2760
2761         return 0;
2762 }
2763
2764 static void __exit dm_writecache_exit(void)
2765 {
2766         dm_unregister_target(&writecache_target);
2767 }
2768
2769 module_init(dm_writecache_init);
2770 module_exit(dm_writecache_exit);
2771
2772 MODULE_DESCRIPTION(DM_NAME " writecache target");
2773 MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
2774 MODULE_LICENSE("GPL");