drivers/md/dm-writecache.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   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 #if BITS_PER_LONG == 64
  87         bool write_in_progress : 1;
  88         unsigned long index : 47;
  89 #else
  90         bool write_in_progress;
  91         unsigned long index;
  92 #endif
  93         unsigned long age;
  94 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
  95         uint64_t original_sector;
  96         uint64_t seq_count;
  97 #endif
  98 };
  99
 100 #ifdef DM_WRITECACHE_HAS_PMEM
 101 #define WC_MODE_PMEM(wc)                        ((wc)->pmem_mode)
 102 #define WC_MODE_FUA(wc)                         ((wc)->writeback_fua)
 103 #else
 104 #define WC_MODE_PMEM(wc)                        false
 105 #define WC_MODE_FUA(wc)                         false
 106 #endif
 107 #define WC_MODE_SORT_FREELIST(wc)               (!WC_MODE_PMEM(wc))
 108
 109 struct dm_writecache {
 110         struct mutex lock;
 111         struct list_head lru;
 112         union {
 113                 struct list_head freelist;
 114                 struct {
 115                         struct rb_root freetree;
 116                         struct wc_entry *current_free;
 117                 };
 118         };
 119         struct rb_root tree;
 120
 121         size_t freelist_size;
 122         size_t writeback_size;
 123         size_t freelist_high_watermark;
 124         size_t freelist_low_watermark;
 125         unsigned long max_age;
 126         unsigned long pause;
 127
 128         unsigned int uncommitted_blocks;
 129         unsigned int autocommit_blocks;
 130         unsigned int max_writeback_jobs;
 131
 132         int error;
 133
 134         unsigned long autocommit_jiffies;
 135         struct timer_list autocommit_timer;
 136         struct wait_queue_head freelist_wait;
 137
 138         struct timer_list max_age_timer;
 139
 140         atomic_t bio_in_progress[2];
 141         struct wait_queue_head bio_in_progress_wait[2];
 142
 143         struct dm_target *ti;
 144         struct dm_dev *dev;
 145         struct dm_dev *ssd_dev;
 146         sector_t start_sector;
 147         void *memory_map;
 148         uint64_t memory_map_size;
 149         size_t metadata_sectors;
 150         size_t n_blocks;
 151         uint64_t seq_count;
 152         sector_t data_device_sectors;
 153         void *block_start;
 154         struct wc_entry *entries;
 155         unsigned int block_size;
 156         unsigned char block_size_bits;
 157
 158         bool pmem_mode:1;
 159         bool writeback_fua:1;
 160
 161         bool overwrote_committed:1;
 162         bool memory_vmapped:1;
 163
 164         bool start_sector_set:1;
 165         bool high_wm_percent_set:1;
 166         bool low_wm_percent_set:1;
 167         bool max_writeback_jobs_set:1;
 168         bool autocommit_blocks_set:1;
 169         bool autocommit_time_set:1;
 170         bool max_age_set:1;
 171         bool writeback_fua_set:1;
 172         bool flush_on_suspend:1;
 173         bool cleaner:1;
 174         bool cleaner_set:1;
 175         bool metadata_only:1;
 176         bool pause_set:1;
 177
 178         unsigned int high_wm_percent_value;
 179         unsigned int low_wm_percent_value;
 180         unsigned int autocommit_time_value;
 181         unsigned int max_age_value;
 182         unsigned int pause_value;
 183
 184         unsigned int writeback_all;
 185         struct workqueue_struct *writeback_wq;
 186         struct work_struct writeback_work;
 187         struct work_struct flush_work;
 188
 189         struct dm_io_tracker iot;
 190
 191         struct dm_io_client *dm_io;
 192
 193         raw_spinlock_t endio_list_lock;
 194         struct list_head endio_list;
 195         struct task_struct *endio_thread;
 196
 197         struct task_struct *flush_thread;
 198         struct bio_list flush_list;
 199
 200         struct dm_kcopyd_client *dm_kcopyd;
 201         unsigned long *dirty_bitmap;
 202         unsigned int dirty_bitmap_size;
 203
 204         struct bio_set bio_set;
 205         mempool_t copy_pool;
 206
 207         struct {
 208                 unsigned long long reads;
 209                 unsigned long long read_hits;
 210                 unsigned long long writes;
 211                 unsigned long long write_hits_uncommitted;
 212                 unsigned long long write_hits_committed;
 213                 unsigned long long writes_around;
 214                 unsigned long long writes_allocate;
 215                 unsigned long long writes_blocked_on_freelist;
 216                 unsigned long long flushes;
 217                 unsigned long long discards;
 218         } stats;
 219 };
 220
 221 #define WB_LIST_INLINE          16
 222
 223 struct writeback_struct {
 224         struct list_head endio_entry;
 225         struct dm_writecache *wc;
 226         struct wc_entry **wc_list;
 227         unsigned int wc_list_n;
 228         struct wc_entry *wc_list_inline[WB_LIST_INLINE];
 229         struct bio bio;
 230 };
 231
 232 struct copy_struct {
 233         struct list_head endio_entry;
 234         struct dm_writecache *wc;
 235         struct wc_entry *e;
 236         unsigned int n_entries;
 237         int error;
 238 };
 239
 240 DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(dm_writecache_throttle,
 241                                             "A percentage of time allocated for data copying");
 242
 243 static void wc_lock(struct dm_writecache *wc)
 244 {
 245         mutex_lock(&wc->lock);
 246 }
 247
 248 static void wc_unlock(struct dm_writecache *wc)
 249 {
 250         mutex_unlock(&wc->lock);
 251 }
 252
 253 #ifdef DM_WRITECACHE_HAS_PMEM
 254 static int persistent_memory_claim(struct dm_writecache *wc)
 255 {
 256         int r;
 257         loff_t s;
 258         long p, da;
 259         pfn_t pfn;
 260         int id;
 261         struct page **pages;
 262         sector_t offset;
 263
 264         wc->memory_vmapped = false;
 265
 266         s = wc->memory_map_size;
 267         p = s >> PAGE_SHIFT;
 268         if (!p) {
 269                 r = -EINVAL;
 270                 goto err1;
 271         }
 272         if (p != s >> PAGE_SHIFT) {
 273                 r = -EOVERFLOW;
 274                 goto err1;
 275         }
 276
 277         offset = get_start_sect(wc->ssd_dev->bdev);
 278         if (offset & (PAGE_SIZE / 512 - 1)) {
 279                 r = -EINVAL;
 280                 goto err1;
 281         }
 282         offset >>= PAGE_SHIFT - 9;
 283
 284         id = dax_read_lock();
 285
 286         da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, DAX_ACCESS,
 287                         &wc->memory_map, &pfn);
 288         if (da < 0) {
 289                 wc->memory_map = NULL;
 290                 r = da;
 291                 goto err2;
 292         }
 293         if (!pfn_t_has_page(pfn)) {
 294                 wc->memory_map = NULL;
 295                 r = -EOPNOTSUPP;
 296                 goto err2;
 297         }
 298         if (da != p) {
 299                 long i;
 300
 301                 wc->memory_map = NULL;
 302                 pages = vmalloc_array(p, sizeof(struct page *));
 303                 if (!pages) {
 304                         r = -ENOMEM;
 305                         goto err2;
 306                 }
 307                 i = 0;
 308                 do {
 309                         long daa;
 310
 311                         daa = dax_direct_access(wc->ssd_dev->dax_dev, offset + i,
 312                                         p - i, DAX_ACCESS, NULL, &pfn);
 313                         if (daa <= 0) {
 314                                 r = daa ? daa : -EINVAL;
 315                                 goto err3;
 316                         }
 317                         if (!pfn_t_has_page(pfn)) {
 318                                 r = -EOPNOTSUPP;
 319                                 goto err3;
 320                         }
 321                         while (daa-- && i < p) {
 322                                 pages[i++] = pfn_t_to_page(pfn);
 323                                 pfn.val++;
 324                                 if (!(i & 15))
 325                                         cond_resched();
 326                         }
 327                 } while (i < p);
 328                 wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
 329                 if (!wc->memory_map) {
 330                         r = -ENOMEM;
 331                         goto err3;
 332                 }
 333                 vfree(pages);
 334                 wc->memory_vmapped = true;
 335         }
 336
 337         dax_read_unlock(id);
 338
 339         wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT;
 340         wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT;
 341
 342         return 0;
 343 err3:
 344         vfree(pages);
 345 err2:
 346         dax_read_unlock(id);
 347 err1:
 348         return r;
 349 }
 350 #else
 351 static int persistent_memory_claim(struct dm_writecache *wc)
 352 {
 353         return -EOPNOTSUPP;
 354 }
 355 #endif
 356
 357 static void persistent_memory_release(struct dm_writecache *wc)
 358 {
 359         if (wc->memory_vmapped)
 360                 vunmap(wc->memory_map - ((size_t)wc->start_sector << SECTOR_SHIFT));
 361 }
 362
 363 static struct page *persistent_memory_page(void *addr)
 364 {
 365         if (is_vmalloc_addr(addr))
 366                 return vmalloc_to_page(addr);
 367         else
 368                 return virt_to_page(addr);
 369 }
 370
 371 static unsigned int persistent_memory_page_offset(void *addr)
 372 {
 373         return (unsigned long)addr & (PAGE_SIZE - 1);
 374 }
 375
 376 static void persistent_memory_flush_cache(void *ptr, size_t size)
 377 {
 378         if (is_vmalloc_addr(ptr))
 379                 flush_kernel_vmap_range(ptr, size);
 380 }
 381
 382 static void persistent_memory_invalidate_cache(void *ptr, size_t size)
 383 {
 384         if (is_vmalloc_addr(ptr))
 385                 invalidate_kernel_vmap_range(ptr, size);
 386 }
 387
 388 static struct wc_memory_superblock *sb(struct dm_writecache *wc)
 389 {
 390         return wc->memory_map;
 391 }
 392
 393 static struct wc_memory_entry *memory_entry(struct dm_writecache *wc, struct wc_entry *e)
 394 {
 395         return &sb(wc)->entries[e->index];
 396 }
 397
 398 static void *memory_data(struct dm_writecache *wc, struct wc_entry *e)
 399 {
 400         return (char *)wc->block_start + (e->index << wc->block_size_bits);
 401 }
 402
 403 static sector_t cache_sector(struct dm_writecache *wc, struct wc_entry *e)
 404 {
 405         return wc->start_sector + wc->metadata_sectors +
 406                 ((sector_t)e->index << (wc->block_size_bits - SECTOR_SHIFT));
 407 }
 408
 409 static uint64_t read_original_sector(struct dm_writecache *wc, struct wc_entry *e)
 410 {
 411 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 412         return e->original_sector;
 413 #else
 414         return le64_to_cpu(memory_entry(wc, e)->original_sector);
 415 #endif
 416 }
 417
 418 static uint64_t read_seq_count(struct dm_writecache *wc, struct wc_entry *e)
 419 {
 420 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 421         return e->seq_count;
 422 #else
 423         return le64_to_cpu(memory_entry(wc, e)->seq_count);
 424 #endif
 425 }
 426
 427 static void clear_seq_count(struct dm_writecache *wc, struct wc_entry *e)
 428 {
 429 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 430         e->seq_count = -1;
 431 #endif
 432         pmem_assign(memory_entry(wc, e)->seq_count, cpu_to_le64(-1));
 433 }
 434
 435 static void write_original_sector_seq_count(struct dm_writecache *wc, struct wc_entry *e,
 436                                             uint64_t original_sector, uint64_t seq_count)
 437 {
 438         struct wc_memory_entry me;
 439 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
 440         e->original_sector = original_sector;
 441         e->seq_count = seq_count;
 442 #endif
 443         me.original_sector = cpu_to_le64(original_sector);
 444         me.seq_count = cpu_to_le64(seq_count);
 445         pmem_assign(*memory_entry(wc, e), me);
 446 }
 447
 448 #define writecache_error(wc, err, msg, arg...)                          \
 449 do {                                                                    \
 450         if (!cmpxchg(&(wc)->error, 0, err))                             \
 451                 DMERR(msg, ##arg);                                      \
 452         wake_up(&(wc)->freelist_wait);                                  \
 453 } while (0)
 454
 455 #define writecache_has_error(wc)        (unlikely(READ_ONCE((wc)->error)))
 456
 457 static void writecache_flush_all_metadata(struct dm_writecache *wc)
 458 {
 459         if (!WC_MODE_PMEM(wc))
 460                 memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
 461 }
 462
 463 static void writecache_flush_region(struct dm_writecache *wc, void *ptr, size_t size)
 464 {
 465         if (!WC_MODE_PMEM(wc))
 466                 __set_bit(((char *)ptr - (char *)wc->memory_map) / BITMAP_GRANULARITY,
 467                           wc->dirty_bitmap);
 468 }
 469
 470 static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev);
 471
 472 struct io_notify {
 473         struct dm_writecache *wc;
 474         struct completion c;
 475         atomic_t count;
 476 };
 477
 478 static void writecache_notify_io(unsigned long error, void *context)
 479 {
 480         struct io_notify *endio = context;
 481
 482         if (unlikely(error != 0))
 483                 writecache_error(endio->wc, -EIO, "error writing metadata");
 484         BUG_ON(atomic_read(&endio->count) <= 0);
 485         if (atomic_dec_and_test(&endio->count))
 486                 complete(&endio->c);
 487 }
 488
 489 static void writecache_wait_for_ios(struct dm_writecache *wc, int direction)
 490 {
 491         wait_event(wc->bio_in_progress_wait[direction],
 492                    !atomic_read(&wc->bio_in_progress[direction]));
 493 }
 494
 495 static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
 496 {
 497         struct dm_io_region region;
 498         struct dm_io_request req;
 499         struct io_notify endio = {
 500                 wc,
 501                 COMPLETION_INITIALIZER_ONSTACK(endio.c),
 502                 ATOMIC_INIT(1),
 503         };
 504         unsigned int bitmap_bits = wc->dirty_bitmap_size * 8;
 505         unsigned int i = 0;
 506
 507         while (1) {
 508                 unsigned int j;
 509
 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, IOPRIO_DEFAULT);
 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, IOPRIO_DEFAULT);
 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, IOPRIO_DEFAULT);
 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
 629                         node = rb_next(&e->rb_node);
 630                         if (unlikely(!node))
 631                                 return NULL;
 632
 633                         e = container_of(node, struct wc_entry, rb_node);
 634                         return e;
 635                 }
 636         }
 637
 638         while (1) {
 639                 struct wc_entry *e2;
 640
 641                 if (flags & WFE_LOWEST_SEQ)
 642                         node = rb_prev(&e->rb_node);
 643                 else
 644                         node = rb_next(&e->rb_node);
 645                 if (unlikely(!node))
 646                         return e;
 647                 e2 = container_of(node, struct wc_entry, rb_node);
 648                 if (read_original_sector(wc, e2) != block)
 649                         return e;
 650                 e = e2;
 651         }
 652 }
 653
 654 static void writecache_insert_entry(struct dm_writecache *wc, struct wc_entry *ins)
 655 {
 656         struct wc_entry *e;
 657         struct rb_node **node = &wc->tree.rb_node, *parent = NULL;
 658
 659         while (*node) {
 660                 e = container_of(*node, struct wc_entry, rb_node);
 661                 parent = &e->rb_node;
 662                 if (read_original_sector(wc, e) > read_original_sector(wc, ins))
 663                         node = &parent->rb_left;
 664                 else
 665                         node = &parent->rb_right;
 666         }
 667         rb_link_node(&ins->rb_node, parent, node);
 668         rb_insert_color(&ins->rb_node, &wc->tree);
 669         list_add(&ins->lru, &wc->lru);
 670         ins->age = jiffies;
 671 }
 672
 673 static void writecache_unlink(struct dm_writecache *wc, struct wc_entry *e)
 674 {
 675         list_del(&e->lru);
 676         rb_erase(&e->rb_node, &wc->tree);
 677 }
 678
 679 static void writecache_add_to_freelist(struct dm_writecache *wc, struct wc_entry *e)
 680 {
 681         if (WC_MODE_SORT_FREELIST(wc)) {
 682                 struct rb_node **node = &wc->freetree.rb_node, *parent = NULL;
 683
 684                 if (unlikely(!*node))
 685                         wc->current_free = e;
 686                 while (*node) {
 687                         parent = *node;
 688                         if (&e->rb_node < *node)
 689                                 node = &parent->rb_left;
 690                         else
 691                                 node = &parent->rb_right;
 692                 }
 693                 rb_link_node(&e->rb_node, parent, node);
 694                 rb_insert_color(&e->rb_node, &wc->freetree);
 695         } else {
 696                 list_add_tail(&e->lru, &wc->freelist);
 697         }
 698         wc->freelist_size++;
 699 }
 700
 701 static inline void writecache_verify_watermark(struct dm_writecache *wc)
 702 {
 703         if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
 704                 queue_work(wc->writeback_wq, &wc->writeback_work);
 705 }
 706
 707 static void writecache_max_age_timer(struct timer_list *t)
 708 {
 709         struct dm_writecache *wc = from_timer(wc, t, max_age_timer);
 710
 711         if (!dm_suspended(wc->ti) && !writecache_has_error(wc)) {
 712                 queue_work(wc->writeback_wq, &wc->writeback_work);
 713                 mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
 714         }
 715 }
 716
 717 static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc, sector_t expected_sector)
 718 {
 719         struct wc_entry *e;
 720
 721         if (WC_MODE_SORT_FREELIST(wc)) {
 722                 struct rb_node *next;
 723
 724                 if (unlikely(!wc->current_free))
 725                         return NULL;
 726                 e = wc->current_free;
 727                 if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
 728                         return NULL;
 729                 next = rb_next(&e->rb_node);
 730                 rb_erase(&e->rb_node, &wc->freetree);
 731                 if (unlikely(!next))
 732                         next = rb_first(&wc->freetree);
 733                 wc->current_free = next ? container_of(next, struct wc_entry, rb_node) : NULL;
 734         } else {
 735                 if (unlikely(list_empty(&wc->freelist)))
 736                         return NULL;
 737                 e = container_of(wc->freelist.next, struct wc_entry, lru);
 738                 if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
 739                         return NULL;
 740                 list_del(&e->lru);
 741         }
 742         wc->freelist_size--;
 743
 744         writecache_verify_watermark(wc);
 745
 746         return e;
 747 }
 748
 749 static void writecache_free_entry(struct dm_writecache *wc, struct wc_entry *e)
 750 {
 751         writecache_unlink(wc, e);
 752         writecache_add_to_freelist(wc, e);
 753         clear_seq_count(wc, e);
 754         writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
 755         if (unlikely(waitqueue_active(&wc->freelist_wait)))
 756                 wake_up(&wc->freelist_wait);
 757 }
 758
 759 static void writecache_wait_on_freelist(struct dm_writecache *wc)
 760 {
 761         DEFINE_WAIT(wait);
 762
 763         prepare_to_wait(&wc->freelist_wait, &wait, TASK_UNINTERRUPTIBLE);
 764         wc_unlock(wc);
 765         io_schedule();
 766         finish_wait(&wc->freelist_wait, &wait);
 767         wc_lock(wc);
 768 }
 769
 770 static void writecache_poison_lists(struct dm_writecache *wc)
 771 {
 772         /*
 773          * Catch incorrect access to these values while the device is suspended.
 774          */
 775         memset(&wc->tree, -1, sizeof(wc->tree));
 776         wc->lru.next = LIST_POISON1;
 777         wc->lru.prev = LIST_POISON2;
 778         wc->freelist.next = LIST_POISON1;
 779         wc->freelist.prev = LIST_POISON2;
 780 }
 781
 782 static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
 783 {
 784         writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
 785         if (WC_MODE_PMEM(wc))
 786                 writecache_flush_region(wc, memory_data(wc, e), wc->block_size);
 787 }
 788
 789 static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
 790 {
 791         return read_seq_count(wc, e) < wc->seq_count;
 792 }
 793
 794 static void writecache_flush(struct dm_writecache *wc)
 795 {
 796         struct wc_entry *e, *e2;
 797         bool need_flush_after_free;
 798
 799         wc->uncommitted_blocks = 0;
 800         del_timer(&wc->autocommit_timer);
 801
 802         if (list_empty(&wc->lru))
 803                 return;
 804
 805         e = container_of(wc->lru.next, struct wc_entry, lru);
 806         if (writecache_entry_is_committed(wc, e)) {
 807                 if (wc->overwrote_committed) {
 808                         writecache_wait_for_ios(wc, WRITE);
 809                         writecache_disk_flush(wc, wc->ssd_dev);
 810                         wc->overwrote_committed = false;
 811                 }
 812                 return;
 813         }
 814         while (1) {
 815                 writecache_flush_entry(wc, e);
 816                 if (unlikely(e->lru.next == &wc->lru))
 817                         break;
 818                 e2 = container_of(e->lru.next, struct wc_entry, lru);
 819                 if (writecache_entry_is_committed(wc, e2))
 820                         break;
 821                 e = e2;
 822                 cond_resched();
 823         }
 824         writecache_commit_flushed(wc, true);
 825
 826         wc->seq_count++;
 827         pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
 828         if (WC_MODE_PMEM(wc))
 829                 writecache_commit_flushed(wc, false);
 830         else
 831                 ssd_commit_superblock(wc);
 832
 833         wc->overwrote_committed = false;
 834
 835         need_flush_after_free = false;
 836         while (1) {
 837                 /* Free another committed entry with lower seq-count */
 838                 struct rb_node *rb_node = rb_prev(&e->rb_node);
 839
 840                 if (rb_node) {
 841                         e2 = container_of(rb_node, struct wc_entry, rb_node);
 842                         if (read_original_sector(wc, e2) == read_original_sector(wc, e) &&
 843                             likely(!e2->write_in_progress)) {
 844                                 writecache_free_entry(wc, e2);
 845                                 need_flush_after_free = true;
 846                         }
 847                 }
 848                 if (unlikely(e->lru.prev == &wc->lru))
 849                         break;
 850                 e = container_of(e->lru.prev, struct wc_entry, lru);
 851                 cond_resched();
 852         }
 853
 854         if (need_flush_after_free)
 855                 writecache_commit_flushed(wc, false);
 856 }
 857
 858 static void writecache_flush_work(struct work_struct *work)
 859 {
 860         struct dm_writecache *wc = container_of(work, struct dm_writecache, flush_work);
 861
 862         wc_lock(wc);
 863         writecache_flush(wc);
 864         wc_unlock(wc);
 865 }
 866
 867 static void writecache_autocommit_timer(struct timer_list *t)
 868 {
 869         struct dm_writecache *wc = from_timer(wc, t, autocommit_timer);
 870
 871         if (!writecache_has_error(wc))
 872                 queue_work(wc->writeback_wq, &wc->flush_work);
 873 }
 874
 875 static void writecache_schedule_autocommit(struct dm_writecache *wc)
 876 {
 877         if (!timer_pending(&wc->autocommit_timer))
 878                 mod_timer(&wc->autocommit_timer, jiffies + wc->autocommit_jiffies);
 879 }
 880
 881 static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_t end)
 882 {
 883         struct wc_entry *e;
 884         bool discarded_something = false;
 885
 886         e = writecache_find_entry(wc, start, WFE_RETURN_FOLLOWING | WFE_LOWEST_SEQ);
 887         if (unlikely(!e))
 888                 return;
 889
 890         while (read_original_sector(wc, e) < end) {
 891                 struct rb_node *node = rb_next(&e->rb_node);
 892
 893                 if (likely(!e->write_in_progress)) {
 894                         if (!discarded_something) {
 895                                 if (!WC_MODE_PMEM(wc)) {
 896                                         writecache_wait_for_ios(wc, READ);
 897                                         writecache_wait_for_ios(wc, WRITE);
 898                                 }
 899                                 discarded_something = true;
 900                         }
 901                         if (!writecache_entry_is_committed(wc, e))
 902                                 wc->uncommitted_blocks--;
 903                         writecache_free_entry(wc, e);
 904                 }
 905
 906                 if (unlikely(!node))
 907                         break;
 908
 909                 e = container_of(node, struct wc_entry, rb_node);
 910         }
 911
 912         if (discarded_something)
 913                 writecache_commit_flushed(wc, false);
 914 }
 915
 916 static bool writecache_wait_for_writeback(struct dm_writecache *wc)
 917 {
 918         if (wc->writeback_size) {
 919                 writecache_wait_on_freelist(wc);
 920                 return true;
 921         }
 922         return false;
 923 }
 924
 925 static void writecache_suspend(struct dm_target *ti)
 926 {
 927         struct dm_writecache *wc = ti->private;
 928         bool flush_on_suspend;
 929
 930         del_timer_sync(&wc->autocommit_timer);
 931         del_timer_sync(&wc->max_age_timer);
 932
 933         wc_lock(wc);
 934         writecache_flush(wc);
 935         flush_on_suspend = wc->flush_on_suspend;
 936         if (flush_on_suspend) {
 937                 wc->flush_on_suspend = false;
 938                 wc->writeback_all++;
 939                 queue_work(wc->writeback_wq, &wc->writeback_work);
 940         }
 941         wc_unlock(wc);
 942
 943         drain_workqueue(wc->writeback_wq);
 944
 945         wc_lock(wc);
 946         if (flush_on_suspend)
 947                 wc->writeback_all--;
 948         while (writecache_wait_for_writeback(wc))
 949                 ;
 950
 951         if (WC_MODE_PMEM(wc))
 952                 persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
 953
 954         writecache_poison_lists(wc);
 955
 956         wc_unlock(wc);
 957 }
 958
 959 static int writecache_alloc_entries(struct dm_writecache *wc)
 960 {
 961         size_t b;
 962
 963         if (wc->entries)
 964                 return 0;
 965         wc->entries = vmalloc_array(wc->n_blocks, sizeof(struct wc_entry));
 966         if (!wc->entries)
 967                 return -ENOMEM;
 968         for (b = 0; b < wc->n_blocks; b++) {
 969                 struct wc_entry *e = &wc->entries[b];
 970
 971                 e->index = b;
 972                 e->write_in_progress = false;
 973                 cond_resched();
 974         }
 975
 976         return 0;
 977 }
 978
 979 static int writecache_read_metadata(struct dm_writecache *wc, sector_t n_sectors)
 980 {
 981         struct dm_io_region region;
 982         struct dm_io_request req;
 983
 984         region.bdev = wc->ssd_dev->bdev;
 985         region.sector = wc->start_sector;
 986         region.count = n_sectors;
 987         req.bi_opf = REQ_OP_READ | REQ_SYNC;
 988         req.mem.type = DM_IO_VMA;
 989         req.mem.ptr.vma = (char *)wc->memory_map;
 990         req.client = wc->dm_io;
 991         req.notify.fn = NULL;
 992
 993         return dm_io(&req, 1, &region, NULL, IOPRIO_DEFAULT);
 994 }
 995
 996 static void writecache_resume(struct dm_target *ti)
 997 {
 998         struct dm_writecache *wc = ti->private;
 999         size_t b;
1000         bool need_flush = false;
1001         __le64 sb_seq_count;
1002         int r;
1003
1004         wc_lock(wc);
1005
1006         wc->data_device_sectors = bdev_nr_sectors(wc->dev->bdev);
1007
1008         if (WC_MODE_PMEM(wc)) {
1009                 persistent_memory_invalidate_cache(wc->memory_map, wc->memory_map_size);
1010         } else {
1011                 r = writecache_read_metadata(wc, wc->metadata_sectors);
1012                 if (r) {
1013                         size_t sb_entries_offset;
1014
1015                         writecache_error(wc, r, "unable to read metadata: %d", r);
1016                         sb_entries_offset = offsetof(struct wc_memory_superblock, entries);
1017                         memset((char *)wc->memory_map + sb_entries_offset, -1,
1018                                (wc->metadata_sectors << SECTOR_SHIFT) - sb_entries_offset);
1019                 }
1020         }
1021
1022         wc->tree = RB_ROOT;
1023         INIT_LIST_HEAD(&wc->lru);
1024         if (WC_MODE_SORT_FREELIST(wc)) {
1025                 wc->freetree = RB_ROOT;
1026                 wc->current_free = NULL;
1027         } else {
1028                 INIT_LIST_HEAD(&wc->freelist);
1029         }
1030         wc->freelist_size = 0;
1031
1032         r = copy_mc_to_kernel(&sb_seq_count, &sb(wc)->seq_count,
1033                               sizeof(uint64_t));
1034         if (r) {
1035                 writecache_error(wc, r, "hardware memory error when reading superblock: %d", r);
1036                 sb_seq_count = cpu_to_le64(0);
1037         }
1038         wc->seq_count = le64_to_cpu(sb_seq_count);
1039
1040 #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
1041         for (b = 0; b < wc->n_blocks; b++) {
1042                 struct wc_entry *e = &wc->entries[b];
1043                 struct wc_memory_entry wme;
1044
1045                 if (writecache_has_error(wc)) {
1046                         e->original_sector = -1;
1047                         e->seq_count = -1;
1048                         continue;
1049                 }
1050                 r = copy_mc_to_kernel(&wme, memory_entry(wc, e),
1051                                       sizeof(struct wc_memory_entry));
1052                 if (r) {
1053                         writecache_error(wc, r, "hardware memory error when reading metadata entry %lu: %d",
1054                                          (unsigned long)b, r);
1055                         e->original_sector = -1;
1056                         e->seq_count = -1;
1057                 } else {
1058                         e->original_sector = le64_to_cpu(wme.original_sector);
1059                         e->seq_count = le64_to_cpu(wme.seq_count);
1060                 }
1061                 cond_resched();
1062         }
1063 #endif
1064         for (b = 0; b < wc->n_blocks; b++) {
1065                 struct wc_entry *e = &wc->entries[b];
1066
1067                 if (!writecache_entry_is_committed(wc, e)) {
1068                         if (read_seq_count(wc, e) != -1) {
1069 erase_this:
1070                                 clear_seq_count(wc, e);
1071                                 need_flush = true;
1072                         }
1073                         writecache_add_to_freelist(wc, e);
1074                 } else {
1075                         struct wc_entry *old;
1076
1077                         old = writecache_find_entry(wc, read_original_sector(wc, e), 0);
1078                         if (!old) {
1079                                 writecache_insert_entry(wc, e);
1080                         } else {
1081                                 if (read_seq_count(wc, old) == read_seq_count(wc, e)) {
1082                                         writecache_error(wc, -EINVAL,
1083                                                  "two identical entries, position %llu, sector %llu, sequence %llu",
1084                                                  (unsigned long long)b, (unsigned long long)read_original_sector(wc, e),
1085                                                  (unsigned long long)read_seq_count(wc, e));
1086                                 }
1087                                 if (read_seq_count(wc, old) > read_seq_count(wc, e)) {
1088                                         goto erase_this;
1089                                 } else {
1090                                         writecache_free_entry(wc, old);
1091                                         writecache_insert_entry(wc, e);
1092                                         need_flush = true;
1093                                 }
1094                         }
1095                 }
1096                 cond_resched();
1097         }
1098
1099         if (need_flush) {
1100                 writecache_flush_all_metadata(wc);
1101                 writecache_commit_flushed(wc, false);
1102         }
1103
1104         writecache_verify_watermark(wc);
1105
1106         if (wc->max_age != MAX_AGE_UNSPECIFIED)
1107                 mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV);
1108
1109         wc_unlock(wc);
1110 }
1111
1112 static int process_flush_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1113 {
1114         if (argc != 1)
1115                 return -EINVAL;
1116
1117         wc_lock(wc);
1118         if (dm_suspended(wc->ti)) {
1119                 wc_unlock(wc);
1120                 return -EBUSY;
1121         }
1122         if (writecache_has_error(wc)) {
1123                 wc_unlock(wc);
1124                 return -EIO;
1125         }
1126
1127         writecache_flush(wc);
1128         wc->writeback_all++;
1129         queue_work(wc->writeback_wq, &wc->writeback_work);
1130         wc_unlock(wc);
1131
1132         flush_workqueue(wc->writeback_wq);
1133
1134         wc_lock(wc);
1135         wc->writeback_all--;
1136         if (writecache_has_error(wc)) {
1137                 wc_unlock(wc);
1138                 return -EIO;
1139         }
1140         wc_unlock(wc);
1141
1142         return 0;
1143 }
1144
1145 static int process_flush_on_suspend_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1146 {
1147         if (argc != 1)
1148                 return -EINVAL;
1149
1150         wc_lock(wc);
1151         wc->flush_on_suspend = true;
1152         wc_unlock(wc);
1153
1154         return 0;
1155 }
1156
1157 static void activate_cleaner(struct dm_writecache *wc)
1158 {
1159         wc->flush_on_suspend = true;
1160         wc->cleaner = true;
1161         wc->freelist_high_watermark = wc->n_blocks;
1162         wc->freelist_low_watermark = wc->n_blocks;
1163 }
1164
1165 static int process_cleaner_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1166 {
1167         if (argc != 1)
1168                 return -EINVAL;
1169
1170         wc_lock(wc);
1171         activate_cleaner(wc);
1172         if (!dm_suspended(wc->ti))
1173                 writecache_verify_watermark(wc);
1174         wc_unlock(wc);
1175
1176         return 0;
1177 }
1178
1179 static int process_clear_stats_mesg(unsigned int argc, char **argv, struct dm_writecache *wc)
1180 {
1181         if (argc != 1)
1182                 return -EINVAL;
1183
1184         wc_lock(wc);
1185         memset(&wc->stats, 0, sizeof(wc->stats));
1186         wc_unlock(wc);
1187
1188         return 0;
1189 }
1190
1191 static int writecache_message(struct dm_target *ti, unsigned int argc, char **argv,
1192                               char *result, unsigned int maxlen)
1193 {
1194         int r = -EINVAL;
1195         struct dm_writecache *wc = ti->private;
1196
1197         if (!strcasecmp(argv[0], "flush"))
1198                 r = process_flush_mesg(argc, argv, wc);
1199         else if (!strcasecmp(argv[0], "flush_on_suspend"))
1200                 r = process_flush_on_suspend_mesg(argc, argv, wc);
1201         else if (!strcasecmp(argv[0], "cleaner"))
1202                 r = process_cleaner_mesg(argc, argv, wc);
1203         else if (!strcasecmp(argv[0], "clear_stats"))
1204                 r = process_clear_stats_mesg(argc, argv, wc);
1205         else
1206                 DMERR("unrecognised message received: %s", argv[0]);
1207
1208         return r;
1209 }
1210
1211 static void memcpy_flushcache_optimized(void *dest, void *source, size_t size)
1212 {
1213         /*
1214          * clflushopt performs better with block size 1024, 2048, 4096
1215          * non-temporal stores perform better with block size 512
1216          *
1217          * block size   512             1024            2048            4096
1218          * movnti       496 MB/s        642 MB/s        725 MB/s        744 MB/s
1219          * clflushopt   373 MB/s        688 MB/s        1.1 GB/s        1.2 GB/s
1220          *
1221          * We see that movnti performs better for 512-byte blocks, and
1222          * clflushopt performs better for 1024-byte and larger blocks. So, we
1223          * prefer clflushopt for sizes >= 768.
1224          *
1225          * NOTE: this happens to be the case now (with dm-writecache's single
1226          * threaded model) but re-evaluate this once memcpy_flushcache() is
1227          * enabled to use movdir64b which might invalidate this performance
1228          * advantage seen with cache-allocating-writes plus flushing.
1229          */
1230 #ifdef CONFIG_X86
1231         if (static_cpu_has(X86_FEATURE_CLFLUSHOPT) &&
1232             likely(boot_cpu_data.x86_clflush_size == 64) &&
1233             likely(size >= 768)) {
1234                 do {
1235                         memcpy((void *)dest, (void *)source, 64);
1236                         clflushopt((void *)dest);
1237                         dest += 64;
1238                         source += 64;
1239                         size -= 64;
1240                 } while (size >= 64);
1241                 return;
1242         }
1243 #endif
1244         memcpy_flushcache(dest, source, size);
1245 }
1246
1247 static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data)
1248 {
1249         void *buf;
1250         unsigned int size;
1251         int rw = bio_data_dir(bio);
1252         unsigned int remaining_size = wc->block_size;
1253
1254         do {
1255                 struct bio_vec bv = bio_iter_iovec(bio, bio->bi_iter);
1256
1257                 buf = bvec_kmap_local(&bv);
1258                 size = bv.bv_len;
1259                 if (unlikely(size > remaining_size))
1260                         size = remaining_size;
1261
1262                 if (rw == READ) {
1263                         int r;
1264
1265                         r = copy_mc_to_kernel(buf, data, size);
1266                         flush_dcache_page(bio_page(bio));
1267                         if (unlikely(r)) {
1268                                 writecache_error(wc, r, "hardware memory error when reading data: %d", r);
1269                                 bio->bi_status = BLK_STS_IOERR;
1270                         }
1271                 } else {
1272                         flush_dcache_page(bio_page(bio));
1273                         memcpy_flushcache_optimized(data, buf, size);
1274                 }
1275
1276                 kunmap_local(buf);
1277
1278                 data = (char *)data + size;
1279                 remaining_size -= size;
1280                 bio_advance(bio, size);
1281         } while (unlikely(remaining_size));
1282 }
1283
1284 static int writecache_flush_thread(void *data)
1285 {
1286         struct dm_writecache *wc = data;
1287
1288         while (1) {
1289                 struct bio *bio;
1290
1291                 wc_lock(wc);
1292                 bio = bio_list_pop(&wc->flush_list);
1293                 if (!bio) {
1294                         set_current_state(TASK_INTERRUPTIBLE);
1295                         wc_unlock(wc);
1296
1297                         if (unlikely(kthread_should_stop())) {
1298                                 set_current_state(TASK_RUNNING);
1299                                 break;
1300                         }
1301
1302                         schedule();
1303                         continue;
1304                 }
1305
1306                 if (bio_op(bio) == REQ_OP_DISCARD) {
1307                         writecache_discard(wc, bio->bi_iter.bi_sector,
1308                                            bio_end_sector(bio));
1309                         wc_unlock(wc);
1310                         bio_set_dev(bio, wc->dev->bdev);
1311                         submit_bio_noacct(bio);
1312                 } else {
1313                         writecache_flush(wc);
1314                         wc_unlock(wc);
1315                         if (writecache_has_error(wc))
1316                                 bio->bi_status = BLK_STS_IOERR;
1317                         bio_endio(bio);
1318                 }
1319         }
1320
1321         return 0;
1322 }
1323
1324 static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
1325 {
1326         if (bio_list_empty(&wc->flush_list))
1327                 wake_up_process(wc->flush_thread);
1328         bio_list_add(&wc->flush_list, bio);
1329 }
1330
1331 enum wc_map_op {
1332         WC_MAP_SUBMIT,
1333         WC_MAP_REMAP,
1334         WC_MAP_REMAP_ORIGIN,
1335         WC_MAP_RETURN,
1336         WC_MAP_ERROR,
1337 };
1338
1339 static void writecache_map_remap_origin(struct dm_writecache *wc, struct bio *bio,
1340                                         struct wc_entry *e)
1341 {
1342         if (e) {
1343                 sector_t next_boundary =
1344                         read_original_sector(wc, e) - bio->bi_iter.bi_sector;
1345                 if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT)
1346                         dm_accept_partial_bio(bio, next_boundary);
1347         }
1348 }
1349
1350 static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *bio)
1351 {
1352         enum wc_map_op map_op;
1353         struct wc_entry *e;
1354
1355 read_next_block:
1356         wc->stats.reads++;
1357         e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1358         if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
1359                 wc->stats.read_hits++;
1360                 if (WC_MODE_PMEM(wc)) {
1361                         bio_copy_block(wc, bio, memory_data(wc, e));
1362                         if (bio->bi_iter.bi_size)
1363                                 goto read_next_block;
1364                         map_op = WC_MAP_SUBMIT;
1365                 } else {
1366                         dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
1367                         bio_set_dev(bio, wc->ssd_dev->bdev);
1368                         bio->bi_iter.bi_sector = cache_sector(wc, e);
1369                         if (!writecache_entry_is_committed(wc, e))
1370                                 writecache_wait_for_ios(wc, WRITE);
1371                         map_op = WC_MAP_REMAP;
1372                 }
1373         } else {
1374                 writecache_map_remap_origin(wc, bio, e);
1375                 wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1376                 map_op = WC_MAP_REMAP_ORIGIN;
1377         }
1378
1379         return map_op;
1380 }
1381
1382 static void writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
1383                                     struct wc_entry *e, bool search_used)
1384 {
1385         unsigned int bio_size = wc->block_size;
1386         sector_t start_cache_sec = cache_sector(wc, e);
1387         sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
1388
1389         while (bio_size < bio->bi_iter.bi_size) {
1390                 if (!search_used) {
1391                         struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
1392
1393                         if (!f)
1394                                 break;
1395                         write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
1396                                                         (bio_size >> SECTOR_SHIFT), wc->seq_count);
1397                         writecache_insert_entry(wc, f);
1398                         wc->uncommitted_blocks++;
1399                 } else {
1400                         struct wc_entry *f;
1401                         struct rb_node *next = rb_next(&e->rb_node);
1402
1403                         if (!next)
1404                                 break;
1405                         f = container_of(next, struct wc_entry, rb_node);
1406                         if (f != e + 1)
1407                                 break;
1408                         if (read_original_sector(wc, f) !=
1409                             read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1410                                 break;
1411                         if (unlikely(f->write_in_progress))
1412                                 break;
1413                         if (writecache_entry_is_committed(wc, f))
1414                                 wc->overwrote_committed = true;
1415                         e = f;
1416                 }
1417                 bio_size += wc->block_size;
1418                 current_cache_sec += wc->block_size >> SECTOR_SHIFT;
1419         }
1420
1421         bio_set_dev(bio, wc->ssd_dev->bdev);
1422         bio->bi_iter.bi_sector = start_cache_sec;
1423         dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
1424
1425         wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1426         wc->stats.writes_allocate += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
1427
1428         if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
1429                 wc->uncommitted_blocks = 0;
1430                 queue_work(wc->writeback_wq, &wc->flush_work);
1431         } else {
1432                 writecache_schedule_autocommit(wc);
1433         }
1434 }
1435
1436 static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
1437 {
1438         struct wc_entry *e;
1439
1440         do {
1441                 bool found_entry = false;
1442                 bool search_used = false;
1443
1444                 if (writecache_has_error(wc)) {
1445                         wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1446                         return WC_MAP_ERROR;
1447                 }
1448                 e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
1449                 if (e) {
1450                         if (!writecache_entry_is_committed(wc, e)) {
1451                                 wc->stats.write_hits_uncommitted++;
1452                                 search_used = true;
1453                                 goto bio_copy;
1454                         }
1455                         wc->stats.write_hits_committed++;
1456                         if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
1457                                 wc->overwrote_committed = true;
1458                                 search_used = true;
1459                                 goto bio_copy;
1460                         }
1461                         found_entry = true;
1462                 } else {
1463                         if (unlikely(wc->cleaner) ||
1464                             (wc->metadata_only && !(bio->bi_opf & REQ_META)))
1465                                 goto direct_write;
1466                 }
1467                 e = writecache_pop_from_freelist(wc, (sector_t)-1);
1468                 if (unlikely(!e)) {
1469                         if (!WC_MODE_PMEM(wc) && !found_entry) {
1470 direct_write:
1471                                 e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
1472                                 writecache_map_remap_origin(wc, bio, e);
1473                                 wc->stats.writes_around += bio->bi_iter.bi_size >> wc->block_size_bits;
1474                                 wc->stats.writes += bio->bi_iter.bi_size >> wc->block_size_bits;
1475                                 return WC_MAP_REMAP_ORIGIN;
1476                         }
1477                         wc->stats.writes_blocked_on_freelist++;
1478                         writecache_wait_on_freelist(wc);
1479                         continue;
1480                 }
1481                 write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
1482                 writecache_insert_entry(wc, e);
1483                 wc->uncommitted_blocks++;
1484                 wc->stats.writes_allocate++;
1485 bio_copy:
1486                 if (WC_MODE_PMEM(wc)) {
1487                         bio_copy_block(wc, bio, memory_data(wc, e));
1488                         wc->stats.writes++;
1489                 } else {
1490                         writecache_bio_copy_ssd(wc, bio, e, search_used);
1491                         return WC_MAP_REMAP;
1492                 }
1493         } while (bio->bi_iter.bi_size);
1494
1495         if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks))
1496                 writecache_flush(wc);
1497         else
1498                 writecache_schedule_autocommit(wc);
1499
1500         return WC_MAP_SUBMIT;
1501 }
1502
1503 static enum wc_map_op writecache_map_flush(struct dm_writecache *wc, struct bio *bio)
1504 {
1505         if (writecache_has_error(wc))
1506                 return WC_MAP_ERROR;
1507
1508         if (WC_MODE_PMEM(wc)) {
1509                 wc->stats.flushes++;
1510                 writecache_flush(wc);
1511                 if (writecache_has_error(wc))
1512                         return WC_MAP_ERROR;
1513                 else if (unlikely(wc->cleaner) || unlikely(wc->metadata_only))
1514                         return WC_MAP_REMAP_ORIGIN;
1515                 return WC_MAP_SUBMIT;
1516         }
1517         /* SSD: */
1518         if (dm_bio_get_target_bio_nr(bio))
1519                 return WC_MAP_REMAP_ORIGIN;
1520         wc->stats.flushes++;
1521         writecache_offload_bio(wc, bio);
1522         return WC_MAP_RETURN;
1523 }
1524
1525 static enum wc_map_op writecache_map_discard(struct dm_writecache *wc, struct bio *bio)
1526 {
1527         wc->stats.discards += bio->bi_iter.bi_size >> wc->block_size_bits;
1528
1529         if (writecache_has_error(wc))
1530                 return WC_MAP_ERROR;
1531
1532         if (WC_MODE_PMEM(wc)) {
1533                 writecache_discard(wc, bio->bi_iter.bi_sector, bio_end_sector(bio));
1534                 return WC_MAP_REMAP_ORIGIN;
1535         }
1536         /* SSD: */
1537         writecache_offload_bio(wc, bio);
1538         return WC_MAP_RETURN;
1539 }
1540
1541 static int writecache_map(struct dm_target *ti, struct bio *bio)
1542 {
1543         struct dm_writecache *wc = ti->private;
1544         enum wc_map_op map_op;
1545
1546         bio->bi_private = NULL;
1547
1548         wc_lock(wc);
1549
1550         if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
1551                 map_op = writecache_map_flush(wc, bio);
1552                 goto done;
1553         }
1554
1555         bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
1556
1557         if (unlikely((((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
1558                                 (wc->block_size / 512 - 1)) != 0)) {
1559                 DMERR("I/O is not aligned, sector %llu, size %u, block size %u",
1560                       (unsigned long long)bio->bi_iter.bi_sector,
1561                       bio->bi_iter.bi_size, wc->block_size);
1562                 map_op = WC_MAP_ERROR;
1563                 goto done;
1564         }
1565
1566         if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
1567                 map_op = writecache_map_discard(wc, bio);
1568                 goto done;
1569         }
1570
1571         if (bio_data_dir(bio) == READ)
1572                 map_op = writecache_map_read(wc, bio);
1573         else
1574                 map_op = writecache_map_write(wc, bio);
1575 done:
1576         switch (map_op) {
1577         case WC_MAP_REMAP_ORIGIN:
1578                 if (likely(wc->pause != 0)) {
1579                         if (bio_op(bio) == REQ_OP_WRITE) {
1580                                 dm_iot_io_begin(&wc->iot, 1);
1581                                 bio->bi_private = (void *)2;
1582                         }
1583                 }
1584                 bio_set_dev(bio, wc->dev->bdev);
1585                 wc_unlock(wc);
1586                 return DM_MAPIO_REMAPPED;
1587
1588         case WC_MAP_REMAP:
1589                 /* make sure that writecache_end_io decrements bio_in_progress: */
1590                 bio->bi_private = (void *)1;
1591                 atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
1592                 wc_unlock(wc);
1593                 return DM_MAPIO_REMAPPED;
1594
1595         case WC_MAP_SUBMIT:
1596                 wc_unlock(wc);
1597                 bio_endio(bio);
1598                 return DM_MAPIO_SUBMITTED;
1599
1600         case WC_MAP_RETURN:
1601                 wc_unlock(wc);
1602                 return DM_MAPIO_SUBMITTED;
1603
1604         case WC_MAP_ERROR:
1605                 wc_unlock(wc);
1606                 bio_io_error(bio);
1607                 return DM_MAPIO_SUBMITTED;
1608
1609         default:
1610                 BUG();
1611                 wc_unlock(wc);
1612                 return DM_MAPIO_KILL;
1613         }
1614 }
1615
1616 static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status)
1617 {
1618         struct dm_writecache *wc = ti->private;
1619
1620         if (bio->bi_private == (void *)1) {
1621                 int dir = bio_data_dir(bio);
1622
1623                 if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
1624                         if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
1625                                 wake_up(&wc->bio_in_progress_wait[dir]);
1626         } else if (bio->bi_private == (void *)2) {
1627                 dm_iot_io_end(&wc->iot, 1);
1628         }
1629         return 0;
1630 }
1631
1632 static int writecache_iterate_devices(struct dm_target *ti,
1633                                       iterate_devices_callout_fn fn, void *data)
1634 {
1635         struct dm_writecache *wc = ti->private;
1636
1637         return fn(ti, wc->dev, 0, ti->len, data);
1638 }
1639
1640 static void writecache_io_hints(struct dm_target *ti, struct queue_limits *limits)
1641 {
1642         struct dm_writecache *wc = ti->private;
1643
1644         if (limits->logical_block_size < wc->block_size)
1645                 limits->logical_block_size = wc->block_size;
1646
1647         if (limits->physical_block_size < wc->block_size)
1648                 limits->physical_block_size = wc->block_size;
1649
1650         if (limits->io_min < wc->block_size)
1651                 limits->io_min = wc->block_size;
1652 }
1653
1654
1655 static void writecache_writeback_endio(struct bio *bio)
1656 {
1657         struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
1658         struct dm_writecache *wc = wb->wc;
1659         unsigned long flags;
1660
1661         raw_spin_lock_irqsave(&wc->endio_list_lock, flags);
1662         if (unlikely(list_empty(&wc->endio_list)))
1663                 wake_up_process(wc->endio_thread);
1664         list_add_tail(&wb->endio_entry, &wc->endio_list);
1665         raw_spin_unlock_irqrestore(&wc->endio_list_lock, flags);
1666 }
1667
1668 static void writecache_copy_endio(int read_err, unsigned long write_err, void *ptr)
1669 {
1670         struct copy_struct *c = ptr;
1671         struct dm_writecache *wc = c->wc;
1672
1673         c->error = likely(!(read_err | write_err)) ? 0 : -EIO;
1674
1675         raw_spin_lock_irq(&wc->endio_list_lock);
1676         if (unlikely(list_empty(&wc->endio_list)))
1677                 wake_up_process(wc->endio_thread);
1678         list_add_tail(&c->endio_entry, &wc->endio_list);
1679         raw_spin_unlock_irq(&wc->endio_list_lock);
1680 }
1681
1682 static void __writecache_endio_pmem(struct dm_writecache *wc, struct list_head *list)
1683 {
1684         unsigned int i;
1685         struct writeback_struct *wb;
1686         struct wc_entry *e;
1687         unsigned long n_walked = 0;
1688
1689         do {
1690                 wb = list_entry(list->next, struct writeback_struct, endio_entry);
1691                 list_del(&wb->endio_entry);
1692
1693                 if (unlikely(wb->bio.bi_status != BLK_STS_OK))
1694                         writecache_error(wc, blk_status_to_errno(wb->bio.bi_status),
1695                                         "write error %d", wb->bio.bi_status);
1696                 i = 0;
1697                 do {
1698                         e = wb->wc_list[i];
1699                         BUG_ON(!e->write_in_progress);
1700                         e->write_in_progress = false;
1701                         INIT_LIST_HEAD(&e->lru);
1702                         if (!writecache_has_error(wc))
1703                                 writecache_free_entry(wc, e);
1704                         BUG_ON(!wc->writeback_size);
1705                         wc->writeback_size--;
1706                         n_walked++;
1707                         if (unlikely(n_walked >= ENDIO_LATENCY)) {
1708                                 writecache_commit_flushed(wc, false);
1709                                 wc_unlock(wc);
1710                                 wc_lock(wc);
1711                                 n_walked = 0;
1712                         }
1713                 } while (++i < wb->wc_list_n);
1714
1715                 if (wb->wc_list != wb->wc_list_inline)
1716                         kfree(wb->wc_list);
1717                 bio_put(&wb->bio);
1718         } while (!list_empty(list));
1719 }
1720
1721 static void __writecache_endio_ssd(struct dm_writecache *wc, struct list_head *list)
1722 {
1723         struct copy_struct *c;
1724         struct wc_entry *e;
1725
1726         do {
1727                 c = list_entry(list->next, struct copy_struct, endio_entry);
1728                 list_del(&c->endio_entry);
1729
1730                 if (unlikely(c->error))
1731                         writecache_error(wc, c->error, "copy error");
1732
1733                 e = c->e;
1734                 do {
1735                         BUG_ON(!e->write_in_progress);
1736                         e->write_in_progress = false;
1737                         INIT_LIST_HEAD(&e->lru);
1738                         if (!writecache_has_error(wc))
1739                                 writecache_free_entry(wc, e);
1740
1741                         BUG_ON(!wc->writeback_size);
1742                         wc->writeback_size--;
1743                         e++;
1744                 } while (--c->n_entries);
1745                 mempool_free(c, &wc->copy_pool);
1746         } while (!list_empty(list));
1747 }
1748
1749 static int writecache_endio_thread(void *data)
1750 {
1751         struct dm_writecache *wc = data;
1752
1753         while (1) {
1754                 struct list_head list;
1755
1756                 raw_spin_lock_irq(&wc->endio_list_lock);
1757                 if (!list_empty(&wc->endio_list))
1758                         goto pop_from_list;
1759                 set_current_state(TASK_INTERRUPTIBLE);
1760                 raw_spin_unlock_irq(&wc->endio_list_lock);
1761
1762                 if (unlikely(kthread_should_stop())) {
1763                         set_current_state(TASK_RUNNING);
1764                         break;
1765                 }
1766
1767                 schedule();
1768
1769                 continue;
1770
1771 pop_from_list:
1772                 list = wc->endio_list;
1773                 list.next->prev = list.prev->next = &list;
1774                 INIT_LIST_HEAD(&wc->endio_list);
1775                 raw_spin_unlock_irq(&wc->endio_list_lock);
1776
1777                 if (!WC_MODE_FUA(wc))
1778                         writecache_disk_flush(wc, wc->dev);
1779
1780                 wc_lock(wc);
1781
1782                 if (WC_MODE_PMEM(wc)) {
1783                         __writecache_endio_pmem(wc, &list);
1784                 } else {
1785                         __writecache_endio_ssd(wc, &list);
1786                         writecache_wait_for_ios(wc, READ);
1787                 }
1788
1789                 writecache_commit_flushed(wc, false);
1790
1791                 wc_unlock(wc);
1792         }
1793
1794         return 0;
1795 }
1796
1797 static bool wc_add_block(struct writeback_struct *wb, struct wc_entry *e)
1798 {
1799         struct dm_writecache *wc = wb->wc;
1800         unsigned int block_size = wc->block_size;
1801         void *address = memory_data(wc, e);
1802
1803         persistent_memory_flush_cache(address, block_size);
1804
1805         if (unlikely(bio_end_sector(&wb->bio) >= wc->data_device_sectors))
1806                 return true;
1807
1808         return bio_add_page(&wb->bio, persistent_memory_page(address),
1809                             block_size, persistent_memory_page_offset(address)) != 0;
1810 }
1811
1812 struct writeback_list {
1813         struct list_head list;
1814         size_t size;
1815 };
1816
1817 static void __writeback_throttle(struct dm_writecache *wc, struct writeback_list *wbl)
1818 {
1819         if (unlikely(wc->max_writeback_jobs)) {
1820                 if (READ_ONCE(wc->writeback_size) - wbl->size >= wc->max_writeback_jobs) {
1821                         wc_lock(wc);
1822                         while (wc->writeback_size - wbl->size >= wc->max_writeback_jobs)
1823                                 writecache_wait_on_freelist(wc);
1824                         wc_unlock(wc);
1825                 }
1826         }
1827         cond_resched();
1828 }
1829
1830 static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeback_list *wbl)
1831 {
1832         struct wc_entry *e, *f;
1833         struct bio *bio;
1834         struct writeback_struct *wb;
1835         unsigned int max_pages;
1836
1837         while (wbl->size) {
1838                 wbl->size--;
1839                 e = container_of(wbl->list.prev, struct wc_entry, lru);
1840                 list_del(&e->lru);
1841
1842                 max_pages = e->wc_list_contiguous;
1843
1844                 bio = bio_alloc_bioset(wc->dev->bdev, max_pages, REQ_OP_WRITE,
1845                                        GFP_NOIO, &wc->bio_set);
1846                 wb = container_of(bio, struct writeback_struct, bio);
1847                 wb->wc = wc;
1848                 bio->bi_end_io = writecache_writeback_endio;
1849                 bio->bi_iter.bi_sector = read_original_sector(wc, e);
1850
1851                 if (unlikely(max_pages > WB_LIST_INLINE))
1852                         wb->wc_list = kmalloc_array(max_pages, sizeof(struct wc_entry *),
1853                                                     GFP_NOIO | __GFP_NORETRY |
1854                                                     __GFP_NOMEMALLOC | __GFP_NOWARN);
1855
1856                 if (likely(max_pages <= WB_LIST_INLINE) || unlikely(!wb->wc_list)) {
1857                         wb->wc_list = wb->wc_list_inline;
1858                         max_pages = WB_LIST_INLINE;
1859                 }
1860
1861                 BUG_ON(!wc_add_block(wb, e));
1862
1863                 wb->wc_list[0] = e;
1864                 wb->wc_list_n = 1;
1865
1866                 while (wbl->size && wb->wc_list_n < max_pages) {
1867                         f = container_of(wbl->list.prev, struct wc_entry, lru);
1868                         if (read_original_sector(wc, f) !=
1869                             read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
1870                                 break;
1871                         if (!wc_add_block(wb, f))
1872                                 break;
1873                         wbl->size--;
1874                         list_del(&f->lru);
1875                         wb->wc_list[wb->wc_list_n++] = f;
1876                         e = f;
1877                 }
1878                 if (WC_MODE_FUA(wc))
1879                         bio->bi_opf |= REQ_FUA;
1880                 if (writecache_has_error(wc)) {
1881                         bio->bi_status = BLK_STS_IOERR;
1882                         bio_endio(bio);
1883                 } else if (unlikely(!bio_sectors(bio))) {
1884                         bio->bi_status = BLK_STS_OK;
1885                         bio_endio(bio);
1886                 } else {
1887                         submit_bio(bio);
1888                 }
1889
1890                 __writeback_throttle(wc, wbl);
1891         }
1892 }
1893
1894 static void __writecache_writeback_ssd(struct dm_writecache *wc, struct writeback_list *wbl)
1895 {
1896         struct wc_entry *e, *f;
1897         struct dm_io_region from, to;
1898         struct copy_struct *c;
1899
1900         while (wbl->size) {
1901                 unsigned int n_sectors;
1902
1903                 wbl->size--;
1904                 e = container_of(wbl->list.prev, struct wc_entry, lru);
1905                 list_del(&e->lru);
1906
1907                 n_sectors = e->wc_list_contiguous << (wc->block_size_bits - SECTOR_SHIFT);
1908
1909                 from.bdev = wc->ssd_dev->bdev;
1910                 from.sector = cache_sector(wc, e);
1911                 from.count = n_sectors;
1912                 to.bdev = wc->dev->bdev;
1913                 to.sector = read_original_sector(wc, e);
1914                 to.count = n_sectors;
1915
1916                 c = mempool_alloc(&wc->copy_pool, GFP_NOIO);
1917                 c->wc = wc;
1918                 c->e = e;
1919                 c->n_entries = e->wc_list_contiguous;
1920
1921                 while ((n_sectors -= wc->block_size >> SECTOR_SHIFT)) {
1922                         wbl->size--;
1923                         f = container_of(wbl->list.prev, struct wc_entry, lru);
1924                         BUG_ON(f != e + 1);
1925                         list_del(&f->lru);
1926                         e = f;
1927                 }
1928
1929                 if (unlikely(to.sector + to.count > wc->data_device_sectors)) {
1930                         if (to.sector >= wc->data_device_sectors) {
1931                                 writecache_copy_endio(0, 0, c);
1932                                 continue;
1933                         }
1934                         from.count = to.count = wc->data_device_sectors - to.sector;
1935                 }
1936
1937                 dm_kcopyd_copy(wc->dm_kcopyd, &from, 1, &to, 0, writecache_copy_endio, c);
1938
1939                 __writeback_throttle(wc, wbl);
1940         }
1941 }
1942
1943 static void writecache_writeback(struct work_struct *work)
1944 {
1945         struct dm_writecache *wc = container_of(work, struct dm_writecache, writeback_work);
1946         struct blk_plug plug;
1947         struct wc_entry *f, *g, *e = NULL;
1948         struct rb_node *node, *next_node;
1949         struct list_head skipped;
1950         struct writeback_list wbl;
1951         unsigned long n_walked;
1952
1953         if (!WC_MODE_PMEM(wc)) {
1954                 /* Wait for any active kcopyd work on behalf of ssd writeback */
1955                 dm_kcopyd_client_flush(wc->dm_kcopyd);
1956         }
1957
1958         if (likely(wc->pause != 0)) {
1959                 while (1) {
1960                         unsigned long idle;
1961
1962                         if (unlikely(wc->cleaner) || unlikely(wc->writeback_all) ||
1963                             unlikely(dm_suspended(wc->ti)))
1964                                 break;
1965                         idle = dm_iot_idle_time(&wc->iot);
1966                         if (idle >= wc->pause)
1967                                 break;
1968                         idle = wc->pause - idle;
1969                         if (idle > HZ)
1970                                 idle = HZ;
1971                         schedule_timeout_idle(idle);
1972                 }
1973         }
1974
1975         wc_lock(wc);
1976 restart:
1977         if (writecache_has_error(wc)) {
1978                 wc_unlock(wc);
1979                 return;
1980         }
1981
1982         if (unlikely(wc->writeback_all)) {
1983                 if (writecache_wait_for_writeback(wc))
1984                         goto restart;
1985         }
1986
1987         if (wc->overwrote_committed)
1988                 writecache_wait_for_ios(wc, WRITE);
1989
1990         n_walked = 0;
1991         INIT_LIST_HEAD(&skipped);
1992         INIT_LIST_HEAD(&wbl.list);
1993         wbl.size = 0;
1994         while (!list_empty(&wc->lru) &&
1995                (wc->writeback_all ||
1996                 wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark ||
1997                 (jiffies - container_of(wc->lru.prev, struct wc_entry, lru)->age >=
1998                  wc->max_age - wc->max_age / MAX_AGE_DIV))) {
1999
2000                 n_walked++;
2001                 if (unlikely(n_walked > WRITEBACK_LATENCY) &&
2002                     likely(!wc->writeback_all)) {
2003                         if (likely(!dm_suspended(wc->ti)))
2004                                 queue_work(wc->writeback_wq, &wc->writeback_work);
2005                         break;
2006                 }
2007
2008                 if (unlikely(wc->writeback_all)) {
2009                         if (unlikely(!e)) {
2010                                 writecache_flush(wc);
2011                                 e = container_of(rb_first(&wc->tree), struct wc_entry, rb_node);
2012                         } else
2013                                 e = g;
2014                 } else
2015                         e = container_of(wc->lru.prev, struct wc_entry, lru);
2016                 BUG_ON(e->write_in_progress);
2017                 if (unlikely(!writecache_entry_is_committed(wc, e)))
2018                         writecache_flush(wc);
2019
2020                 node = rb_prev(&e->rb_node);
2021                 if (node) {
2022                         f = container_of(node, struct wc_entry, rb_node);
2023                         if (unlikely(read_original_sector(wc, f) ==
2024                                      read_original_sector(wc, e))) {
2025                                 BUG_ON(!f->write_in_progress);
2026                                 list_move(&e->lru, &skipped);
2027                                 cond_resched();
2028                                 continue;
2029                         }
2030                 }
2031                 wc->writeback_size++;
2032                 list_move(&e->lru, &wbl.list);
2033                 wbl.size++;
2034                 e->write_in_progress = true;
2035                 e->wc_list_contiguous = 1;
2036
2037                 f = e;
2038
2039                 while (1) {
2040                         next_node = rb_next(&f->rb_node);
2041                         if (unlikely(!next_node))
2042                                 break;
2043                         g = container_of(next_node, struct wc_entry, rb_node);
2044                         if (unlikely(read_original_sector(wc, g) ==
2045                             read_original_sector(wc, f))) {
2046                                 f = g;
2047                                 continue;
2048                         }
2049                         if (read_original_sector(wc, g) !=
2050                             read_original_sector(wc, f) + (wc->block_size >> SECTOR_SHIFT))
2051                                 break;
2052                         if (unlikely(g->write_in_progress))
2053                                 break;
2054                         if (unlikely(!writecache_entry_is_committed(wc, g)))
2055                                 break;
2056
2057                         if (!WC_MODE_PMEM(wc)) {
2058                                 if (g != f + 1)
2059                                         break;
2060                         }
2061
2062                         n_walked++;
2063                         //if (unlikely(n_walked > WRITEBACK_LATENCY) && likely(!wc->writeback_all))
2064                         //      break;
2065
2066                         wc->writeback_size++;
2067                         list_move(&g->lru, &wbl.list);
2068                         wbl.size++;
2069                         g->write_in_progress = true;
2070                         g->wc_list_contiguous = BIO_MAX_VECS;
2071                         f = g;
2072                         e->wc_list_contiguous++;
2073                         if (unlikely(e->wc_list_contiguous == BIO_MAX_VECS)) {
2074                                 if (unlikely(wc->writeback_all)) {
2075                                         next_node = rb_next(&f->rb_node);
2076                                         if (likely(next_node))
2077                                                 g = container_of(next_node, struct wc_entry, rb_node);
2078                                 }
2079                                 break;
2080                         }
2081                 }
2082                 cond_resched();
2083         }
2084
2085         if (!list_empty(&skipped)) {
2086                 list_splice_tail(&skipped, &wc->lru);
2087                 /*
2088                  * If we didn't do any progress, we must wait until some
2089                  * writeback finishes to avoid burning CPU in a loop
2090                  */
2091                 if (unlikely(!wbl.size))
2092                         writecache_wait_for_writeback(wc);
2093         }
2094
2095         wc_unlock(wc);
2096
2097         blk_start_plug(&plug);
2098
2099         if (WC_MODE_PMEM(wc))
2100                 __writecache_writeback_pmem(wc, &wbl);
2101         else
2102                 __writecache_writeback_ssd(wc, &wbl);
2103
2104         blk_finish_plug(&plug);
2105
2106         if (unlikely(wc->writeback_all)) {
2107                 wc_lock(wc);
2108                 while (writecache_wait_for_writeback(wc))
2109                         ;
2110                 wc_unlock(wc);
2111         }
2112 }
2113
2114 static int calculate_memory_size(uint64_t device_size, unsigned int block_size,
2115                                  size_t *n_blocks_p, size_t *n_metadata_blocks_p)
2116 {
2117         uint64_t n_blocks, offset;
2118         struct wc_entry e;
2119
2120         n_blocks = device_size;
2121         do_div(n_blocks, block_size + sizeof(struct wc_memory_entry));
2122
2123         while (1) {
2124                 if (!n_blocks)
2125                         return -ENOSPC;
2126                 /* Verify the following entries[n_blocks] won't overflow */
2127                 if (n_blocks >= ((size_t)-sizeof(struct wc_memory_superblock) /
2128                                  sizeof(struct wc_memory_entry)))
2129                         return -EFBIG;
2130                 offset = offsetof(struct wc_memory_superblock, entries[n_blocks]);
2131                 offset = (offset + block_size - 1) & ~(uint64_t)(block_size - 1);
2132                 if (offset + n_blocks * block_size <= device_size)
2133                         break;
2134                 n_blocks--;
2135         }
2136
2137         /* check if the bit field overflows */
2138         e.index = n_blocks;
2139         if (e.index != n_blocks)
2140                 return -EFBIG;
2141
2142         if (n_blocks_p)
2143                 *n_blocks_p = n_blocks;
2144         if (n_metadata_blocks_p)
2145                 *n_metadata_blocks_p = offset >> __ffs(block_size);
2146         return 0;
2147 }
2148
2149 static int init_memory(struct dm_writecache *wc)
2150 {
2151         size_t b;
2152         int r;
2153
2154         r = calculate_memory_size(wc->memory_map_size, wc->block_size, &wc->n_blocks, NULL);
2155         if (r)
2156                 return r;
2157
2158         r = writecache_alloc_entries(wc);
2159         if (r)
2160                 return r;
2161
2162         for (b = 0; b < ARRAY_SIZE(sb(wc)->padding); b++)
2163                 pmem_assign(sb(wc)->padding[b], cpu_to_le64(0));
2164         pmem_assign(sb(wc)->version, cpu_to_le32(MEMORY_SUPERBLOCK_VERSION));
2165         pmem_assign(sb(wc)->block_size, cpu_to_le32(wc->block_size));
2166         pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
2167         pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
2168
2169         for (b = 0; b < wc->n_blocks; b++) {
2170                 write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
2171                 cond_resched();
2172         }
2173
2174         writecache_flush_all_metadata(wc);
2175         writecache_commit_flushed(wc, false);
2176         pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
2177         writecache_flush_region(wc, &sb(wc)->magic, sizeof(sb(wc)->magic));
2178         writecache_commit_flushed(wc, false);
2179
2180         return 0;
2181 }
2182
2183 static void writecache_dtr(struct dm_target *ti)
2184 {
2185         struct dm_writecache *wc = ti->private;
2186
2187         if (!wc)
2188                 return;
2189
2190         if (wc->endio_thread)
2191                 kthread_stop(wc->endio_thread);
2192
2193         if (wc->flush_thread)
2194                 kthread_stop(wc->flush_thread);
2195
2196         bioset_exit(&wc->bio_set);
2197
2198         mempool_exit(&wc->copy_pool);
2199
2200         if (wc->writeback_wq)
2201                 destroy_workqueue(wc->writeback_wq);
2202
2203         if (wc->dev)
2204                 dm_put_device(ti, wc->dev);
2205
2206         if (wc->ssd_dev)
2207                 dm_put_device(ti, wc->ssd_dev);
2208
2209         vfree(wc->entries);
2210
2211         if (wc->memory_map) {
2212                 if (WC_MODE_PMEM(wc))
2213                         persistent_memory_release(wc);
2214                 else
2215                         vfree(wc->memory_map);
2216         }
2217
2218         if (wc->dm_kcopyd)
2219                 dm_kcopyd_client_destroy(wc->dm_kcopyd);
2220
2221         if (wc->dm_io)
2222                 dm_io_client_destroy(wc->dm_io);
2223
2224         vfree(wc->dirty_bitmap);
2225
2226         kfree(wc);
2227 }
2228
2229 static int writecache_ctr(struct dm_target *ti, unsigned int argc, char **argv)
2230 {
2231         struct dm_writecache *wc;
2232         struct dm_arg_set as;
2233         const char *string;
2234         unsigned int opt_params;
2235         size_t offset, data_size;
2236         int i, r;
2237         char dummy;
2238         int high_wm_percent = HIGH_WATERMARK;
2239         int low_wm_percent = LOW_WATERMARK;
2240         uint64_t x;
2241         struct wc_memory_superblock s;
2242
2243         static struct dm_arg _args[] = {
2244                 {0, 18, "Invalid number of feature args"},
2245         };
2246
2247         as.argc = argc;
2248         as.argv = argv;
2249
2250         wc = kzalloc(sizeof(struct dm_writecache), GFP_KERNEL);
2251         if (!wc) {
2252                 ti->error = "Cannot allocate writecache structure";
2253                 r = -ENOMEM;
2254                 goto bad;
2255         }
2256         ti->private = wc;
2257         wc->ti = ti;
2258
2259         mutex_init(&wc->lock);
2260         wc->max_age = MAX_AGE_UNSPECIFIED;
2261         writecache_poison_lists(wc);
2262         init_waitqueue_head(&wc->freelist_wait);
2263         timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0);
2264         timer_setup(&wc->max_age_timer, writecache_max_age_timer, 0);
2265
2266         for (i = 0; i < 2; i++) {
2267                 atomic_set(&wc->bio_in_progress[i], 0);
2268                 init_waitqueue_head(&wc->bio_in_progress_wait[i]);
2269         }
2270
2271         wc->dm_io = dm_io_client_create();
2272         if (IS_ERR(wc->dm_io)) {
2273                 r = PTR_ERR(wc->dm_io);
2274                 ti->error = "Unable to allocate dm-io client";
2275                 wc->dm_io = NULL;
2276                 goto bad;
2277         }
2278
2279         wc->writeback_wq = alloc_workqueue("writecache-writeback", WQ_MEM_RECLAIM, 1);
2280         if (!wc->writeback_wq) {
2281                 r = -ENOMEM;
2282                 ti->error = "Could not allocate writeback workqueue";
2283                 goto bad;
2284         }
2285         INIT_WORK(&wc->writeback_work, writecache_writeback);
2286         INIT_WORK(&wc->flush_work, writecache_flush_work);
2287
2288         dm_iot_init(&wc->iot);
2289
2290         raw_spin_lock_init(&wc->endio_list_lock);
2291         INIT_LIST_HEAD(&wc->endio_list);
2292         wc->endio_thread = kthread_run(writecache_endio_thread, wc, "writecache_endio");
2293         if (IS_ERR(wc->endio_thread)) {
2294                 r = PTR_ERR(wc->endio_thread);
2295                 wc->endio_thread = NULL;
2296                 ti->error = "Couldn't spawn endio thread";
2297                 goto bad;
2298         }
2299
2300         /*
2301          * Parse the mode (pmem or ssd)
2302          */
2303         string = dm_shift_arg(&as);
2304         if (!string)
2305                 goto bad_arguments;
2306
2307         if (!strcasecmp(string, "s")) {
2308                 wc->pmem_mode = false;
2309         } else if (!strcasecmp(string, "p")) {
2310 #ifdef DM_WRITECACHE_HAS_PMEM
2311                 wc->pmem_mode = true;
2312                 wc->writeback_fua = true;
2313 #else
2314                 /*
2315                  * If the architecture doesn't support persistent memory or
2316                  * the kernel doesn't support any DAX drivers, this driver can
2317                  * only be used in SSD-only mode.
2318                  */
2319                 r = -EOPNOTSUPP;
2320                 ti->error = "Persistent memory or DAX not supported on this system";
2321                 goto bad;
2322 #endif
2323         } else {
2324                 goto bad_arguments;
2325         }
2326
2327         if (WC_MODE_PMEM(wc)) {
2328                 r = bioset_init(&wc->bio_set, BIO_POOL_SIZE,
2329                                 offsetof(struct writeback_struct, bio),
2330                                 BIOSET_NEED_BVECS);
2331                 if (r) {
2332                         ti->error = "Could not allocate bio set";
2333                         goto bad;
2334                 }
2335         } else {
2336                 wc->pause = PAUSE_WRITEBACK;
2337                 r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
2338                 if (r) {
2339                         ti->error = "Could not allocate mempool";
2340                         goto bad;
2341                 }
2342         }
2343
2344         /*
2345          * Parse the origin data device
2346          */
2347         string = dm_shift_arg(&as);
2348         if (!string)
2349                 goto bad_arguments;
2350         r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->dev);
2351         if (r) {
2352                 ti->error = "Origin data device lookup failed";
2353                 goto bad;
2354         }
2355
2356         /*
2357          * Parse cache data device (be it pmem or ssd)
2358          */
2359         string = dm_shift_arg(&as);
2360         if (!string)
2361                 goto bad_arguments;
2362
2363         r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->ssd_dev);
2364         if (r) {
2365                 ti->error = "Cache data device lookup failed";
2366                 goto bad;
2367         }
2368         wc->memory_map_size = bdev_nr_bytes(wc->ssd_dev->bdev);
2369
2370         /*
2371          * Parse the cache block size
2372          */
2373         string = dm_shift_arg(&as);
2374         if (!string)
2375                 goto bad_arguments;
2376         if (sscanf(string, "%u%c", &wc->block_size, &dummy) != 1 ||
2377             wc->block_size < 512 || wc->block_size > PAGE_SIZE ||
2378             (wc->block_size & (wc->block_size - 1))) {
2379                 r = -EINVAL;
2380                 ti->error = "Invalid block size";
2381                 goto bad;
2382         }
2383         if (wc->block_size < bdev_logical_block_size(wc->dev->bdev) ||
2384             wc->block_size < bdev_logical_block_size(wc->ssd_dev->bdev)) {
2385                 r = -EINVAL;
2386                 ti->error = "Block size is smaller than device logical block size";
2387                 goto bad;
2388         }
2389         wc->block_size_bits = __ffs(wc->block_size);
2390
2391         wc->max_writeback_jobs = MAX_WRITEBACK_JOBS;
2392         wc->autocommit_blocks = !WC_MODE_PMEM(wc) ? AUTOCOMMIT_BLOCKS_SSD : AUTOCOMMIT_BLOCKS_PMEM;
2393         wc->autocommit_jiffies = msecs_to_jiffies(AUTOCOMMIT_MSEC);
2394
2395         /*
2396          * Parse optional arguments
2397          */
2398         r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
2399         if (r)
2400                 goto bad;
2401
2402         while (opt_params) {
2403                 string = dm_shift_arg(&as), opt_params--;
2404                 if (!strcasecmp(string, "start_sector") && opt_params >= 1) {
2405                         unsigned long long start_sector;
2406
2407                         string = dm_shift_arg(&as), opt_params--;
2408                         if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
2409                                 goto invalid_optional;
2410                         wc->start_sector = start_sector;
2411                         wc->start_sector_set = true;
2412                         if (wc->start_sector != start_sector ||
2413                             wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
2414                                 goto invalid_optional;
2415                 } else if (!strcasecmp(string, "high_watermark") && opt_params >= 1) {
2416                         string = dm_shift_arg(&as), opt_params--;
2417                         if (sscanf(string, "%d%c", &high_wm_percent, &dummy) != 1)
2418                                 goto invalid_optional;
2419                         if (high_wm_percent < 0 || high_wm_percent > 100)
2420                                 goto invalid_optional;
2421                         wc->high_wm_percent_value = high_wm_percent;
2422                         wc->high_wm_percent_set = true;
2423                 } else if (!strcasecmp(string, "low_watermark") && opt_params >= 1) {
2424                         string = dm_shift_arg(&as), opt_params--;
2425                         if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
2426                                 goto invalid_optional;
2427                         if (low_wm_percent < 0 || low_wm_percent > 100)
2428                                 goto invalid_optional;
2429                         wc->low_wm_percent_value = low_wm_percent;
2430                         wc->low_wm_percent_set = true;
2431                 } else if (!strcasecmp(string, "writeback_jobs") && opt_params >= 1) {
2432                         string = dm_shift_arg(&as), opt_params--;
2433                         if (sscanf(string, "%u%c", &wc->max_writeback_jobs, &dummy) != 1)
2434                                 goto invalid_optional;
2435                         wc->max_writeback_jobs_set = true;
2436                 } else if (!strcasecmp(string, "autocommit_blocks") && opt_params >= 1) {
2437                         string = dm_shift_arg(&as), opt_params--;
2438                         if (sscanf(string, "%u%c", &wc->autocommit_blocks, &dummy) != 1)
2439                                 goto invalid_optional;
2440                         wc->autocommit_blocks_set = true;
2441                 } else if (!strcasecmp(string, "autocommit_time") && opt_params >= 1) {
2442                         unsigned int autocommit_msecs;
2443
2444                         string = dm_shift_arg(&as), opt_params--;
2445                         if (sscanf(string, "%u%c", &autocommit_msecs, &dummy) != 1)
2446                                 goto invalid_optional;
2447                         if (autocommit_msecs > 3600000)
2448                                 goto invalid_optional;
2449                         wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs);
2450                         wc->autocommit_time_value = autocommit_msecs;
2451                         wc->autocommit_time_set = true;
2452                 } else if (!strcasecmp(string, "max_age") && opt_params >= 1) {
2453                         unsigned int max_age_msecs;
2454
2455                         string = dm_shift_arg(&as), opt_params--;
2456                         if (sscanf(string, "%u%c", &max_age_msecs, &dummy) != 1)
2457                                 goto invalid_optional;
2458                         if (max_age_msecs > 86400000)
2459                                 goto invalid_optional;
2460                         wc->max_age = msecs_to_jiffies(max_age_msecs);
2461                         wc->max_age_set = true;
2462                         wc->max_age_value = max_age_msecs;
2463                 } else if (!strcasecmp(string, "cleaner")) {
2464                         wc->cleaner_set = true;
2465                         wc->cleaner = true;
2466                 } else if (!strcasecmp(string, "fua")) {
2467                         if (WC_MODE_PMEM(wc)) {
2468                                 wc->writeback_fua = true;
2469                                 wc->writeback_fua_set = true;
2470                         } else
2471                                 goto invalid_optional;
2472                 } else if (!strcasecmp(string, "nofua")) {
2473                         if (WC_MODE_PMEM(wc)) {
2474                                 wc->writeback_fua = false;
2475                                 wc->writeback_fua_set = true;
2476                         } else
2477                                 goto invalid_optional;
2478                 } else if (!strcasecmp(string, "metadata_only")) {
2479                         wc->metadata_only = true;
2480                 } else if (!strcasecmp(string, "pause_writeback") && opt_params >= 1) {
2481                         unsigned int pause_msecs;
2482
2483                         if (WC_MODE_PMEM(wc))
2484                                 goto invalid_optional;
2485                         string = dm_shift_arg(&as), opt_params--;
2486                         if (sscanf(string, "%u%c", &pause_msecs, &dummy) != 1)
2487                                 goto invalid_optional;
2488                         if (pause_msecs > 60000)
2489                                 goto invalid_optional;
2490                         wc->pause = msecs_to_jiffies(pause_msecs);
2491                         wc->pause_set = true;
2492                         wc->pause_value = pause_msecs;
2493                 } else {
2494 invalid_optional:
2495                         r = -EINVAL;
2496                         ti->error = "Invalid optional argument";
2497                         goto bad;
2498                 }
2499         }
2500
2501         if (high_wm_percent < low_wm_percent) {
2502                 r = -EINVAL;
2503                 ti->error = "High watermark must be greater than or equal to low watermark";
2504                 goto bad;
2505         }
2506
2507         if (WC_MODE_PMEM(wc)) {
2508                 if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
2509                         r = -EOPNOTSUPP;
2510                         ti->error = "Asynchronous persistent memory not supported as pmem cache";
2511                         goto bad;
2512                 }
2513
2514                 r = persistent_memory_claim(wc);
2515                 if (r) {
2516                         ti->error = "Unable to map persistent memory for cache";
2517                         goto bad;
2518                 }
2519         } else {
2520                 size_t n_blocks, n_metadata_blocks;
2521                 uint64_t n_bitmap_bits;
2522
2523                 wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
2524
2525                 bio_list_init(&wc->flush_list);
2526                 wc->flush_thread = kthread_run(writecache_flush_thread, wc, "dm_writecache_flush");
2527                 if (IS_ERR(wc->flush_thread)) {
2528                         r = PTR_ERR(wc->flush_thread);
2529                         wc->flush_thread = NULL;
2530                         ti->error = "Couldn't spawn flush thread";
2531                         goto bad;
2532                 }
2533
2534                 r = calculate_memory_size(wc->memory_map_size, wc->block_size,
2535                                           &n_blocks, &n_metadata_blocks);
2536                 if (r) {
2537                         ti->error = "Invalid device size";
2538                         goto bad;
2539                 }
2540
2541                 n_bitmap_bits = (((uint64_t)n_metadata_blocks << wc->block_size_bits) +
2542                                  BITMAP_GRANULARITY - 1) / BITMAP_GRANULARITY;
2543                 /* this is limitation of test_bit functions */
2544                 if (n_bitmap_bits > 1U << 31) {
2545                         r = -EFBIG;
2546                         ti->error = "Invalid device size";
2547                         goto bad;
2548                 }
2549
2550                 wc->memory_map = vmalloc(n_metadata_blocks << wc->block_size_bits);
2551                 if (!wc->memory_map) {
2552                         r = -ENOMEM;
2553                         ti->error = "Unable to allocate memory for metadata";
2554                         goto bad;
2555                 }
2556
2557                 wc->dm_kcopyd = dm_kcopyd_client_create(&dm_kcopyd_throttle);
2558                 if (IS_ERR(wc->dm_kcopyd)) {
2559                         r = PTR_ERR(wc->dm_kcopyd);
2560                         ti->error = "Unable to allocate dm-kcopyd client";
2561                         wc->dm_kcopyd = NULL;
2562                         goto bad;
2563                 }
2564
2565                 wc->metadata_sectors = n_metadata_blocks << (wc->block_size_bits - SECTOR_SHIFT);
2566                 wc->dirty_bitmap_size = (n_bitmap_bits + BITS_PER_LONG - 1) /
2567                         BITS_PER_LONG * sizeof(unsigned long);
2568                 wc->dirty_bitmap = vzalloc(wc->dirty_bitmap_size);
2569                 if (!wc->dirty_bitmap) {
2570                         r = -ENOMEM;
2571                         ti->error = "Unable to allocate dirty bitmap";
2572                         goto bad;
2573                 }
2574
2575                 r = writecache_read_metadata(wc, wc->block_size >> SECTOR_SHIFT);
2576                 if (r) {
2577                         ti->error = "Unable to read first block of metadata";
2578                         goto bad;
2579                 }
2580         }
2581
2582         r = copy_mc_to_kernel(&s, sb(wc), sizeof(struct wc_memory_superblock));
2583         if (r) {
2584                 ti->error = "Hardware memory error when reading superblock";
2585                 goto bad;
2586         }
2587         if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
2588                 r = init_memory(wc);
2589                 if (r) {
2590                         ti->error = "Unable to initialize device";
2591                         goto bad;
2592                 }
2593                 r = copy_mc_to_kernel(&s, sb(wc),
2594                                       sizeof(struct wc_memory_superblock));
2595                 if (r) {
2596                         ti->error = "Hardware memory error when reading superblock";
2597                         goto bad;
2598                 }
2599         }
2600
2601         if (le32_to_cpu(s.magic) != MEMORY_SUPERBLOCK_MAGIC) {
2602                 ti->error = "Invalid magic in the superblock";
2603                 r = -EINVAL;
2604                 goto bad;
2605         }
2606
2607         if (le32_to_cpu(s.version) != MEMORY_SUPERBLOCK_VERSION) {
2608                 ti->error = "Invalid version in the superblock";
2609                 r = -EINVAL;
2610                 goto bad;
2611         }
2612
2613         if (le32_to_cpu(s.block_size) != wc->block_size) {
2614                 ti->error = "Block size does not match superblock";
2615                 r = -EINVAL;
2616                 goto bad;
2617         }
2618
2619         wc->n_blocks = le64_to_cpu(s.n_blocks);
2620
2621         offset = wc->n_blocks * sizeof(struct wc_memory_entry);
2622         if (offset / sizeof(struct wc_memory_entry) != le64_to_cpu(sb(wc)->n_blocks)) {
2623 overflow:
2624                 ti->error = "Overflow in size calculation";
2625                 r = -EINVAL;
2626                 goto bad;
2627         }
2628         offset += sizeof(struct wc_memory_superblock);
2629         if (offset < sizeof(struct wc_memory_superblock))
2630                 goto overflow;
2631         offset = (offset + wc->block_size - 1) & ~(size_t)(wc->block_size - 1);
2632         data_size = wc->n_blocks * (size_t)wc->block_size;
2633         if (!offset || (data_size / wc->block_size != wc->n_blocks) ||
2634             (offset + data_size < offset))
2635                 goto overflow;
2636         if (offset + data_size > wc->memory_map_size) {
2637                 ti->error = "Memory area is too small";
2638                 r = -EINVAL;
2639                 goto bad;
2640         }
2641
2642         wc->metadata_sectors = offset >> SECTOR_SHIFT;
2643         wc->block_start = (char *)sb(wc) + offset;
2644
2645         x = (uint64_t)wc->n_blocks * (100 - high_wm_percent);
2646         x += 50;
2647         do_div(x, 100);
2648         wc->freelist_high_watermark = x;
2649         x = (uint64_t)wc->n_blocks * (100 - low_wm_percent);
2650         x += 50;
2651         do_div(x, 100);
2652         wc->freelist_low_watermark = x;
2653
2654         if (wc->cleaner)
2655                 activate_cleaner(wc);
2656
2657         r = writecache_alloc_entries(wc);
2658         if (r) {
2659                 ti->error = "Cannot allocate memory";
2660                 goto bad;
2661         }
2662
2663         ti->num_flush_bios = WC_MODE_PMEM(wc) ? 1 : 2;
2664         ti->flush_supported = true;
2665         ti->num_discard_bios = 1;
2666
2667         if (WC_MODE_PMEM(wc))
2668                 persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
2669
2670         return 0;
2671
2672 bad_arguments:
2673         r = -EINVAL;
2674         ti->error = "Bad arguments";
2675 bad:
2676         writecache_dtr(ti);
2677         return r;
2678 }
2679
2680 static void writecache_status(struct dm_target *ti, status_type_t type,
2681                               unsigned int status_flags, char *result, unsigned int maxlen)
2682 {
2683         struct dm_writecache *wc = ti->private;
2684         unsigned int extra_args;
2685         unsigned int sz = 0;
2686
2687         switch (type) {
2688         case STATUSTYPE_INFO:
2689                 DMEMIT("%ld %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu",
2690                        writecache_has_error(wc),
2691                        (unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
2692                        (unsigned long long)wc->writeback_size,
2693                        wc->stats.reads,
2694                        wc->stats.read_hits,
2695                        wc->stats.writes,
2696                        wc->stats.write_hits_uncommitted,
2697                        wc->stats.write_hits_committed,
2698                        wc->stats.writes_around,
2699                        wc->stats.writes_allocate,
2700                        wc->stats.writes_blocked_on_freelist,
2701                        wc->stats.flushes,
2702                        wc->stats.discards);
2703                 break;
2704         case STATUSTYPE_TABLE:
2705                 DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
2706                                 wc->dev->name, wc->ssd_dev->name, wc->block_size);
2707                 extra_args = 0;
2708                 if (wc->start_sector_set)
2709                         extra_args += 2;
2710                 if (wc->high_wm_percent_set)
2711                         extra_args += 2;
2712                 if (wc->low_wm_percent_set)
2713                         extra_args += 2;
2714                 if (wc->max_writeback_jobs_set)
2715                         extra_args += 2;
2716                 if (wc->autocommit_blocks_set)
2717                         extra_args += 2;
2718                 if (wc->autocommit_time_set)
2719                         extra_args += 2;
2720                 if (wc->max_age_set)
2721                         extra_args += 2;
2722                 if (wc->cleaner_set)
2723                         extra_args++;
2724                 if (wc->writeback_fua_set)
2725                         extra_args++;
2726                 if (wc->metadata_only)
2727                         extra_args++;
2728                 if (wc->pause_set)
2729                         extra_args += 2;
2730
2731                 DMEMIT("%u", extra_args);
2732                 if (wc->start_sector_set)
2733                         DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
2734                 if (wc->high_wm_percent_set)
2735                         DMEMIT(" high_watermark %u", wc->high_wm_percent_value);
2736                 if (wc->low_wm_percent_set)
2737                         DMEMIT(" low_watermark %u", wc->low_wm_percent_value);
2738                 if (wc->max_writeback_jobs_set)
2739                         DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
2740                 if (wc->autocommit_blocks_set)
2741                         DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
2742                 if (wc->autocommit_time_set)
2743                         DMEMIT(" autocommit_time %u", wc->autocommit_time_value);
2744                 if (wc->max_age_set)
2745                         DMEMIT(" max_age %u", wc->max_age_value);
2746                 if (wc->cleaner_set)
2747                         DMEMIT(" cleaner");
2748                 if (wc->writeback_fua_set)
2749                         DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
2750                 if (wc->metadata_only)
2751                         DMEMIT(" metadata_only");
2752                 if (wc->pause_set)
2753                         DMEMIT(" pause_writeback %u", wc->pause_value);
2754                 break;
2755         case STATUSTYPE_IMA:
2756                 *result = '\0';
2757                 break;
2758         }
2759 }
2760
2761 static struct target_type writecache_target = {
2762         .name                   = "writecache",
2763         .version                = {1, 6, 0},
2764         .module                 = THIS_MODULE,
2765         .ctr                    = writecache_ctr,
2766         .dtr                    = writecache_dtr,
2767         .status                 = writecache_status,
2768         .postsuspend            = writecache_suspend,
2769         .resume                 = writecache_resume,
2770         .message                = writecache_message,
2771         .map                    = writecache_map,
2772         .end_io                 = writecache_end_io,
2773         .iterate_devices        = writecache_iterate_devices,
2774         .io_hints               = writecache_io_hints,
2775 };
2776 module_dm(writecache);
2777
2778 MODULE_DESCRIPTION(DM_NAME " writecache target");
2779 MODULE_AUTHOR("Mikulas Patocka <dm-devel@lists.linux.dev>");
2780 MODULE_LICENSE("GPL");