root/drivers/md/raid5-cache.c

DEFINITIONS

1. r5c_tree_index
2. r5c_is_writeback
3. r5l_ring_add
4. r5l_ring_distance
5. r5l_has_free_space
6. __r5l_set_io_unit_state
7. r5c_return_dev_pending_writes
8. r5c_handle_cached_data_endio
9. r5c_check_stripe_cache_usage
10. r5c_check_cached_full_stripe
11. r5c_log_required_to_flush_cache
12. r5c_update_log_state
13. r5c_make_stripe_write_out
14. r5c_handle_data_cached
15. r5c_handle_parity_cached
16. r5c_finish_cache_stripe
17. r5l_io_run_stripes
18. r5l_log_run_stripes
19. r5l_move_to_end_ios
20. r5l_log_endio
21. r5l_do_submit_io
22. r5l_submit_io_async
23. r5c_disable_writeback_async
24. r5l_submit_current_io
25. r5l_bio_alloc
26. r5_reserve_log_entry
27. r5l_new_meta
28. r5l_get_meta
29. r5l_append_payload_meta
30. r5l_append_payload_page
31. r5l_append_flush_payload
32. r5l_log_stripe
33. r5l_add_no_space_stripe
34. r5l_write_stripe
35. r5l_write_stripe_run
36. r5l_handle_flush_request
37. r5l_run_no_space_stripes
38. r5c_calculate_new_cp
39. r5l_reclaimable_space
40. r5l_run_no_mem_stripe
41. r5l_complete_finished_ios
42. __r5l_stripe_write_finished
43. r5l_stripe_write_finished
44. r5l_log_flush_endio
45. r5l_flush_stripe_to_raid
46. r5l_write_super_and_discard_space
47. r5c_flush_stripe
48. r5c_flush_cache
49. r5c_do_reclaim
50. r5l_do_reclaim
51. r5l_reclaim_thread
52. r5l_wake_reclaim
53. r5l_quiesce
54. r5l_log_disk_error
55. r5l_recovery_allocate_ra_pool
56. r5l_recovery_free_ra_pool
57. r5l_recovery_fetch_ra_pool
58. r5l_recovery_read_page
59. r5l_recovery_read_meta_block
60. r5l_recovery_create_empty_meta_block
61. r5l_log_write_empty_meta_block
62. r5l_recovery_load_data
63. r5l_recovery_load_parity
64. r5l_recovery_reset_stripe
65. r5l_recovery_replay_one_stripe
66. r5c_recovery_alloc_stripe
67. r5c_recovery_lookup_stripe
68. r5c_recovery_drop_stripes
69. r5c_recovery_replay_stripes
70. r5l_recovery_verify_data_checksum
71. r5l_recovery_verify_data_checksum_for_mb
72. r5c_recovery_analyze_meta_block
73. r5c_recovery_load_one_stripe
74. r5c_recovery_flush_log
75. r5c_recovery_rewrite_data_only_stripes
76. r5c_recovery_flush_data_only_stripes
77. r5l_recovery_log
78. r5l_write_super
79. r5c_journal_mode_show
80. r5c_journal_mode_set
81. r5c_journal_mode_store
82. r5c_try_caching_write
83. r5c_release_extra_page
84. r5c_use_extra_page
85. r5c_finish_stripe_write_out
86. r5c_cache_data
87. r5c_big_stripe_cached
88. r5l_load_log
89. r5l_start
90. r5c_update_on_rdev_error
91. r5l_init_log
92. r5l_exit_log

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2015 Shaohua Li <shli@fb.com>
   4  * Copyright (C) 2016 Song Liu <songliubraving@fb.com>
   5  */
   6 #include <linux/kernel.h>
   7 #include <linux/wait.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/slab.h>
  10 #include <linux/raid/md_p.h>
  11 #include <linux/crc32c.h>
  12 #include <linux/random.h>
  13 #include <linux/kthread.h>
  14 #include <linux/types.h>
  15 #include "md.h"
  16 #include "raid5.h"
  17 #include "md-bitmap.h"
  18 #include "raid5-log.h"
  19 
  20 /*
  21  * metadata/data stored in disk with 4k size unit (a block) regardless
  22  * underneath hardware sector size. only works with PAGE_SIZE == 4096
  23  */
  24 #define BLOCK_SECTORS (8)
  25 #define BLOCK_SECTOR_SHIFT (3)
  26 
  27 /*
  28  * log->max_free_space is min(1/4 disk size, 10G reclaimable space).
  29  *
  30  * In write through mode, the reclaim runs every log->max_free_space.
  31  * This can prevent the recovery scans for too long
  32  */
  33 #define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */
  34 #define RECLAIM_MAX_FREE_SPACE_SHIFT (2)
  35 
  36 /* wake up reclaim thread periodically */
  37 #define R5C_RECLAIM_WAKEUP_INTERVAL (30 * HZ)
  38 /* start flush with these full stripes */
  39 #define R5C_FULL_STRIPE_FLUSH_BATCH(conf) (conf->max_nr_stripes / 4)
  40 /* reclaim stripes in groups */
  41 #define R5C_RECLAIM_STRIPE_GROUP (NR_STRIPE_HASH_LOCKS * 2)
  42 
  43 /*
  44  * We only need 2 bios per I/O unit to make progress, but ensure we
  45  * have a few more available to not get too tight.
  46  */
  47 #define R5L_POOL_SIZE   4
  48 
  49 static char *r5c_journal_mode_str[] = {"write-through",
  50                                        "write-back"};
  51 /*
  52  * raid5 cache state machine
  53  *
  54  * With the RAID cache, each stripe works in two phases:
  55  *      - caching phase
  56  *      - writing-out phase
  57  *
  58  * These two phases are controlled by bit STRIPE_R5C_CACHING:
  59  *   if STRIPE_R5C_CACHING == 0, the stripe is in writing-out phase
  60  *   if STRIPE_R5C_CACHING == 1, the stripe is in caching phase
  61  *
  62  * When there is no journal, or the journal is in write-through mode,
  63  * the stripe is always in writing-out phase.
  64  *
  65  * For write-back journal, the stripe is sent to caching phase on write
  66  * (r5c_try_caching_write). r5c_make_stripe_write_out() kicks off
  67  * the write-out phase by clearing STRIPE_R5C_CACHING.
  68  *
  69  * Stripes in caching phase do not write the raid disks. Instead, all
  70  * writes are committed from the log device. Therefore, a stripe in
  71  * caching phase handles writes as:
  72  *      - write to log device
  73  *      - return IO
  74  *
  75  * Stripes in writing-out phase handle writes as:
  76  *      - calculate parity
  77  *      - write pending data and parity to journal
  78  *      - write data and parity to raid disks
  79  *      - return IO for pending writes
  80  */
  81 
  82 struct r5l_log {
  83         struct md_rdev *rdev;
  84 
  85         u32 uuid_checksum;
  86 
  87         sector_t device_size;           /* log device size, round to
  88                                          * BLOCK_SECTORS */
  89         sector_t max_free_space;        /* reclaim run if free space is at
  90                                          * this size */
  91 
  92         sector_t last_checkpoint;       /* log tail. where recovery scan
  93                                          * starts from */
  94         u64 last_cp_seq;                /* log tail sequence */
  95 
  96         sector_t log_start;             /* log head. where new data appends */
  97         u64 seq;                        /* log head sequence */
  98 
  99         sector_t next_checkpoint;
 100 
 101         struct mutex io_mutex;
 102         struct r5l_io_unit *current_io; /* current io_unit accepting new data */
 103 
 104         spinlock_t io_list_lock;
 105         struct list_head running_ios;   /* io_units which are still running,
 106                                          * and have not yet been completely
 107                                          * written to the log */
 108         struct list_head io_end_ios;    /* io_units which have been completely
 109                                          * written to the log but not yet written
 110                                          * to the RAID */
 111         struct list_head flushing_ios;  /* io_units which are waiting for log
 112                                          * cache flush */
 113         struct list_head finished_ios;  /* io_units which settle down in log disk */
 114         struct bio flush_bio;
 115 
 116         struct list_head no_mem_stripes;   /* pending stripes, -ENOMEM */
 117 
 118         struct kmem_cache *io_kc;
 119         mempool_t io_pool;
 120         struct bio_set bs;
 121         mempool_t meta_pool;
 122 
 123         struct md_thread *reclaim_thread;
 124         unsigned long reclaim_target;   /* number of space that need to be
 125                                          * reclaimed.  if it's 0, reclaim spaces
 126                                          * used by io_units which are in
 127                                          * IO_UNIT_STRIPE_END state (eg, reclaim
 128                                          * dones't wait for specific io_unit
 129                                          * switching to IO_UNIT_STRIPE_END
 130                                          * state) */
 131         wait_queue_head_t iounit_wait;
 132 
 133         struct list_head no_space_stripes; /* pending stripes, log has no space */
 134         spinlock_t no_space_stripes_lock;
 135 
 136         bool need_cache_flush;
 137 
 138         /* for r5c_cache */
 139         enum r5c_journal_mode r5c_journal_mode;
 140 
 141         /* all stripes in r5cache, in the order of seq at sh->log_start */
 142         struct list_head stripe_in_journal_list;
 143 
 144         spinlock_t stripe_in_journal_lock;
 145         atomic_t stripe_in_journal_count;
 146 
 147         /* to submit async io_units, to fulfill ordering of flush */
 148         struct work_struct deferred_io_work;
 149         /* to disable write back during in degraded mode */
 150         struct work_struct disable_writeback_work;
 151 
 152         /* to for chunk_aligned_read in writeback mode, details below */
 153         spinlock_t tree_lock;
 154         struct radix_tree_root big_stripe_tree;
 155 };
 156 
 157 /*
 158  * Enable chunk_aligned_read() with write back cache.
 159  *
 160  * Each chunk may contain more than one stripe (for example, a 256kB
 161  * chunk contains 64 4kB-page, so this chunk contain 64 stripes). For
 162  * chunk_aligned_read, these stripes are grouped into one "big_stripe".
 163  * For each big_stripe, we count how many stripes of this big_stripe
 164  * are in the write back cache. These data are tracked in a radix tree
 165  * (big_stripe_tree). We use radix_tree item pointer as the counter.
 166  * r5c_tree_index() is used to calculate keys for the radix tree.
 167  *
 168  * chunk_aligned_read() calls r5c_big_stripe_cached() to look up
 169  * big_stripe of each chunk in the tree. If this big_stripe is in the
 170  * tree, chunk_aligned_read() aborts. This look up is protected by
 171  * rcu_read_lock().
 172  *
 173  * It is necessary to remember whether a stripe is counted in
 174  * big_stripe_tree. Instead of adding new flag, we reuses existing flags:
 175  * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE. If either of these
 176  * two flags are set, the stripe is counted in big_stripe_tree. This
 177  * requires moving set_bit(STRIPE_R5C_PARTIAL_STRIPE) to
 178  * r5c_try_caching_write(); and moving clear_bit of
 179  * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE to
 180  * r5c_finish_stripe_write_out().
 181  */
 182 
 183 /*
 184  * radix tree requests lowest 2 bits of data pointer to be 2b'00.
 185  * So it is necessary to left shift the counter by 2 bits before using it
 186  * as data pointer of the tree.
 187  */
 188 #define R5C_RADIX_COUNT_SHIFT 2
 189 
 190 /*
 191  * calculate key for big_stripe_tree
 192  *
 193  * sect: align_bi->bi_iter.bi_sector or sh->sector
 194  */
 195 static inline sector_t r5c_tree_index(struct r5conf *conf,
 196                                       sector_t sect)
 197 {
 198         sector_t offset;
 199 
 200         offset = sector_div(sect, conf->chunk_sectors);
 201         return sect;
 202 }
 203 
 204 /*
 205  * an IO range starts from a meta data block and end at the next meta data
 206  * block. The io unit's the meta data block tracks data/parity followed it. io
 207  * unit is written to log disk with normal write, as we always flush log disk
 208  * first and then start move data to raid disks, there is no requirement to
 209  * write io unit with FLUSH/FUA
 210  */
 211 struct r5l_io_unit {
 212         struct r5l_log *log;
 213 
 214         struct page *meta_page; /* store meta block */
 215         int meta_offset;        /* current offset in meta_page */
 216 
 217         struct bio *current_bio;/* current_bio accepting new data */
 218 
 219         atomic_t pending_stripe;/* how many stripes not flushed to raid */
 220         u64 seq;                /* seq number of the metablock */
 221         sector_t log_start;     /* where the io_unit starts */
 222         sector_t log_end;       /* where the io_unit ends */
 223         struct list_head log_sibling; /* log->running_ios */
 224         struct list_head stripe_list; /* stripes added to the io_unit */
 225 
 226         int state;
 227         bool need_split_bio;
 228         struct bio *split_bio;
 229 
 230         unsigned int has_flush:1;               /* include flush request */
 231         unsigned int has_fua:1;                 /* include fua request */
 232         unsigned int has_null_flush:1;          /* include null flush request */
 233         unsigned int has_flush_payload:1;       /* include flush payload  */
 234         /*
 235          * io isn't sent yet, flush/fua request can only be submitted till it's
 236          * the first IO in running_ios list
 237          */
 238         unsigned int io_deferred:1;
 239 
 240         struct bio_list flush_barriers;   /* size == 0 flush bios */
 241 };
 242 
 243 /* r5l_io_unit state */
 244 enum r5l_io_unit_state {
 245         IO_UNIT_RUNNING = 0,    /* accepting new IO */
 246         IO_UNIT_IO_START = 1,   /* io_unit bio start writing to log,
 247                                  * don't accepting new bio */
 248         IO_UNIT_IO_END = 2,     /* io_unit bio finish writing to log */
 249         IO_UNIT_STRIPE_END = 3, /* stripes data finished writing to raid */
 250 };
 251 
 252 bool r5c_is_writeback(struct r5l_log *log)
 253 {
 254         return (log != NULL &&
 255                 log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK);
 256 }
 257 
 258 static sector_t r5l_ring_add(struct r5l_log *log, sector_t start, sector_t inc)
 259 {
 260         start += inc;
 261         if (start >= log->device_size)
 262                 start = start - log->device_size;
 263         return start;
 264 }
 265 
 266 static sector_t r5l_ring_distance(struct r5l_log *log, sector_t start,
 267                                   sector_t end)
 268 {
 269         if (end >= start)
 270                 return end - start;
 271         else
 272                 return end + log->device_size - start;
 273 }
 274 
 275 static bool r5l_has_free_space(struct r5l_log *log, sector_t size)
 276 {
 277         sector_t used_size;
 278 
 279         used_size = r5l_ring_distance(log, log->last_checkpoint,
 280                                         log->log_start);
 281 
 282         return log->device_size > used_size + size;
 283 }
 284 
 285 static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
 286                                     enum r5l_io_unit_state state)
 287 {
 288         if (WARN_ON(io->state >= state))
 289                 return;
 290         io->state = state;
 291 }
 292 
 293 static void
 294 r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev)
 295 {
 296         struct bio *wbi, *wbi2;
 297 
 298         wbi = dev->written;
 299         dev->written = NULL;
 300         while (wbi && wbi->bi_iter.bi_sector <
 301                dev->sector + STRIPE_SECTORS) {
 302                 wbi2 = r5_next_bio(wbi, dev->sector);
 303                 md_write_end(conf->mddev);
 304                 bio_endio(wbi);
 305                 wbi = wbi2;
 306         }
 307 }
 308 
 309 void r5c_handle_cached_data_endio(struct r5conf *conf,
 310                                   struct stripe_head *sh, int disks)
 311 {
 312         int i;
 313 
 314         for (i = sh->disks; i--; ) {
 315                 if (sh->dev[i].written) {
 316                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
 317                         r5c_return_dev_pending_writes(conf, &sh->dev[i]);
 318                         md_bitmap_endwrite(conf->mddev->bitmap, sh->sector,
 319                                            STRIPE_SECTORS,
 320                                            !test_bit(STRIPE_DEGRADED, &sh->state),
 321                                            0);
 322                 }
 323         }
 324 }
 325 
 326 void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
 327 
 328 /* Check whether we should flush some stripes to free up stripe cache */
 329 void r5c_check_stripe_cache_usage(struct r5conf *conf)
 330 {
 331         int total_cached;
 332 
 333         if (!r5c_is_writeback(conf->log))
 334                 return;
 335 
 336         total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
 337                 atomic_read(&conf->r5c_cached_full_stripes);
 338 
 339         /*
 340          * The following condition is true for either of the following:
 341          *   - stripe cache pressure high:
 342          *          total_cached > 3/4 min_nr_stripes ||
 343          *          empty_inactive_list_nr > 0
 344          *   - stripe cache pressure moderate:
 345          *          total_cached > 1/2 min_nr_stripes
 346          */
 347         if (total_cached > conf->min_nr_stripes * 1 / 2 ||
 348             atomic_read(&conf->empty_inactive_list_nr) > 0)
 349                 r5l_wake_reclaim(conf->log, 0);
 350 }
 351 
 352 /*
 353  * flush cache when there are R5C_FULL_STRIPE_FLUSH_BATCH or more full
 354  * stripes in the cache
 355  */
 356 void r5c_check_cached_full_stripe(struct r5conf *conf)
 357 {
 358         if (!r5c_is_writeback(conf->log))
 359                 return;
 360 
 361         /*
 362          * wake up reclaim for R5C_FULL_STRIPE_FLUSH_BATCH cached stripes
 363          * or a full stripe (chunk size / 4k stripes).
 364          */
 365         if (atomic_read(&conf->r5c_cached_full_stripes) >=
 366             min(R5C_FULL_STRIPE_FLUSH_BATCH(conf),
 367                 conf->chunk_sectors >> STRIPE_SHIFT))
 368                 r5l_wake_reclaim(conf->log, 0);
 369 }
 370 
 371 /*
 372  * Total log space (in sectors) needed to flush all data in cache
 373  *
 374  * To avoid deadlock due to log space, it is necessary to reserve log
 375  * space to flush critical stripes (stripes that occupying log space near
 376  * last_checkpoint). This function helps check how much log space is
 377  * required to flush all cached stripes.
 378  *
 379  * To reduce log space requirements, two mechanisms are used to give cache
 380  * flush higher priorities:
 381  *    1. In handle_stripe_dirtying() and schedule_reconstruction(),
 382  *       stripes ALREADY in journal can be flushed w/o pending writes;
 383  *    2. In r5l_write_stripe() and r5c_cache_data(), stripes NOT in journal
 384  *       can be delayed (r5l_add_no_space_stripe).
 385  *
 386  * In cache flush, the stripe goes through 1 and then 2. For a stripe that
 387  * already passed 1, flushing it requires at most (conf->max_degraded + 1)
 388  * pages of journal space. For stripes that has not passed 1, flushing it
 389  * requires (conf->raid_disks + 1) pages of journal space. There are at
 390  * most (conf->group_cnt + 1) stripe that passed 1. So total journal space
 391  * required to flush all cached stripes (in pages) is:
 392  *
 393  *     (stripe_in_journal_count - group_cnt - 1) * (max_degraded + 1) +
 394  *     (group_cnt + 1) * (raid_disks + 1)
 395  * or
 396  *     (stripe_in_journal_count) * (max_degraded + 1) +
 397  *     (group_cnt + 1) * (raid_disks - max_degraded)
 398  */
 399 static sector_t r5c_log_required_to_flush_cache(struct r5conf *conf)
 400 {
 401         struct r5l_log *log = conf->log;
 402 
 403         if (!r5c_is_writeback(log))
 404                 return 0;
 405 
 406         return BLOCK_SECTORS *
 407                 ((conf->max_degraded + 1) * atomic_read(&log->stripe_in_journal_count) +
 408                  (conf->raid_disks - conf->max_degraded) * (conf->group_cnt + 1));
 409 }
 410 
 411 /*
 412  * evaluate log space usage and update R5C_LOG_TIGHT and R5C_LOG_CRITICAL
 413  *
 414  * R5C_LOG_TIGHT is set when free space on the log device is less than 3x of
 415  * reclaim_required_space. R5C_LOG_CRITICAL is set when free space on the log
 416  * device is less than 2x of reclaim_required_space.
 417  */
 418 static inline void r5c_update_log_state(struct r5l_log *log)
 419 {
 420         struct r5conf *conf = log->rdev->mddev->private;
 421         sector_t free_space;
 422         sector_t reclaim_space;
 423         bool wake_reclaim = false;
 424 
 425         if (!r5c_is_writeback(log))
 426                 return;
 427 
 428         free_space = r5l_ring_distance(log, log->log_start,
 429                                        log->last_checkpoint);
 430         reclaim_space = r5c_log_required_to_flush_cache(conf);
 431         if (free_space < 2 * reclaim_space)
 432                 set_bit(R5C_LOG_CRITICAL, &conf->cache_state);
 433         else {
 434                 if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
 435                         wake_reclaim = true;
 436                 clear_bit(R5C_LOG_CRITICAL, &conf->cache_state);
 437         }
 438         if (free_space < 3 * reclaim_space)
 439                 set_bit(R5C_LOG_TIGHT, &conf->cache_state);
 440         else
 441                 clear_bit(R5C_LOG_TIGHT, &conf->cache_state);
 442 
 443         if (wake_reclaim)
 444                 r5l_wake_reclaim(log, 0);
 445 }
 446 
 447 /*
 448  * Put the stripe into writing-out phase by clearing STRIPE_R5C_CACHING.
 449  * This function should only be called in write-back mode.
 450  */
 451 void r5c_make_stripe_write_out(struct stripe_head *sh)
 452 {
 453         struct r5conf *conf = sh->raid_conf;
 454         struct r5l_log *log = conf->log;
 455 
 456         BUG_ON(!r5c_is_writeback(log));
 457 
 458         WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
 459         clear_bit(STRIPE_R5C_CACHING, &sh->state);
 460 
 461         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 462                 atomic_inc(&conf->preread_active_stripes);
 463 }
 464 
 465 static void r5c_handle_data_cached(struct stripe_head *sh)
 466 {
 467         int i;
 468 
 469         for (i = sh->disks; i--; )
 470                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 471                         set_bit(R5_InJournal, &sh->dev[i].flags);
 472                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 473                 }
 474         clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
 475 }
 476 
 477 /*
 478  * this journal write must contain full parity,
 479  * it may also contain some data pages
 480  */
 481 static void r5c_handle_parity_cached(struct stripe_head *sh)
 482 {
 483         int i;
 484 
 485         for (i = sh->disks; i--; )
 486                 if (test_bit(R5_InJournal, &sh->dev[i].flags))
 487                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
 488 }
 489 
 490 /*
 491  * Setting proper flags after writing (or flushing) data and/or parity to the
 492  * log device. This is called from r5l_log_endio() or r5l_log_flush_endio().
 493  */
 494 static void r5c_finish_cache_stripe(struct stripe_head *sh)
 495 {
 496         struct r5l_log *log = sh->raid_conf->log;
 497 
 498         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
 499                 BUG_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
 500                 /*
 501                  * Set R5_InJournal for parity dev[pd_idx]. This means
 502                  * all data AND parity in the journal. For RAID 6, it is
 503                  * NOT necessary to set the flag for dev[qd_idx], as the
 504                  * two parities are written out together.
 505                  */
 506                 set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
 507         } else if (test_bit(STRIPE_R5C_CACHING, &sh->state)) {
 508                 r5c_handle_data_cached(sh);
 509         } else {
 510                 r5c_handle_parity_cached(sh);
 511                 set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
 512         }
 513 }
 514 
 515 static void r5l_io_run_stripes(struct r5l_io_unit *io)
 516 {
 517         struct stripe_head *sh, *next;
 518 
 519         list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
 520                 list_del_init(&sh->log_list);
 521 
 522                 r5c_finish_cache_stripe(sh);
 523 
 524                 set_bit(STRIPE_HANDLE, &sh->state);
 525                 raid5_release_stripe(sh);
 526         }
 527 }
 528 
 529 static void r5l_log_run_stripes(struct r5l_log *log)
 530 {
 531         struct r5l_io_unit *io, *next;
 532 
 533         lockdep_assert_held(&log->io_list_lock);
 534 
 535         list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
 536                 /* don't change list order */
 537                 if (io->state < IO_UNIT_IO_END)
 538                         break;
 539 
 540                 list_move_tail(&io->log_sibling, &log->finished_ios);
 541                 r5l_io_run_stripes(io);
 542         }
 543 }
 544 
 545 static void r5l_move_to_end_ios(struct r5l_log *log)
 546 {
 547         struct r5l_io_unit *io, *next;
 548 
 549         lockdep_assert_held(&log->io_list_lock);
 550 
 551         list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
 552                 /* don't change list order */
 553                 if (io->state < IO_UNIT_IO_END)
 554                         break;
 555                 list_move_tail(&io->log_sibling, &log->io_end_ios);
 556         }
 557 }
 558 
 559 static void __r5l_stripe_write_finished(struct r5l_io_unit *io);
 560 static void r5l_log_endio(struct bio *bio)
 561 {
 562         struct r5l_io_unit *io = bio->bi_private;
 563         struct r5l_io_unit *io_deferred;
 564         struct r5l_log *log = io->log;
 565         unsigned long flags;
 566         bool has_null_flush;
 567         bool has_flush_payload;
 568 
 569         if (bio->bi_status)
 570                 md_error(log->rdev->mddev, log->rdev);
 571 
 572         bio_put(bio);
 573         mempool_free(io->meta_page, &log->meta_pool);
 574 
 575         spin_lock_irqsave(&log->io_list_lock, flags);
 576         __r5l_set_io_unit_state(io, IO_UNIT_IO_END);
 577 
 578         /*
 579          * if the io doesn't not have null_flush or flush payload,
 580          * it is not safe to access it after releasing io_list_lock.
 581          * Therefore, it is necessary to check the condition with
 582          * the lock held.
 583          */
 584         has_null_flush = io->has_null_flush;
 585         has_flush_payload = io->has_flush_payload;
 586 
 587         if (log->need_cache_flush && !list_empty(&io->stripe_list))
 588                 r5l_move_to_end_ios(log);
 589         else
 590                 r5l_log_run_stripes(log);
 591         if (!list_empty(&log->running_ios)) {
 592                 /*
 593                  * FLUSH/FUA io_unit is deferred because of ordering, now we
 594                  * can dispatch it
 595                  */
 596                 io_deferred = list_first_entry(&log->running_ios,
 597                                                struct r5l_io_unit, log_sibling);
 598                 if (io_deferred->io_deferred)
 599                         schedule_work(&log->deferred_io_work);
 600         }
 601 
 602         spin_unlock_irqrestore(&log->io_list_lock, flags);
 603 
 604         if (log->need_cache_flush)
 605                 md_wakeup_thread(log->rdev->mddev->thread);
 606 
 607         /* finish flush only io_unit and PAYLOAD_FLUSH only io_unit */
 608         if (has_null_flush) {
 609                 struct bio *bi;
 610 
 611                 WARN_ON(bio_list_empty(&io->flush_barriers));
 612                 while ((bi = bio_list_pop(&io->flush_barriers)) != NULL) {
 613                         bio_endio(bi);
 614                         if (atomic_dec_and_test(&io->pending_stripe)) {
 615                                 __r5l_stripe_write_finished(io);
 616                                 return;
 617                         }
 618                 }
 619         }
 620         /* decrease pending_stripe for flush payload */
 621         if (has_flush_payload)
 622                 if (atomic_dec_and_test(&io->pending_stripe))
 623                         __r5l_stripe_write_finished(io);
 624 }
 625 
 626 static void r5l_do_submit_io(struct r5l_log *log, struct r5l_io_unit *io)
 627 {
 628         unsigned long flags;
 629 
 630         spin_lock_irqsave(&log->io_list_lock, flags);
 631         __r5l_set_io_unit_state(io, IO_UNIT_IO_START);
 632         spin_unlock_irqrestore(&log->io_list_lock, flags);
 633 
 634         /*
 635          * In case of journal device failures, submit_bio will get error
 636          * and calls endio, then active stripes will continue write
 637          * process. Therefore, it is not necessary to check Faulty bit
 638          * of journal device here.
 639          *
 640          * We can't check split_bio after current_bio is submitted. If
 641          * io->split_bio is null, after current_bio is submitted, current_bio
 642          * might already be completed and the io_unit is freed. We submit
 643          * split_bio first to avoid the issue.
 644          */
 645         if (io->split_bio) {
 646                 if (io->has_flush)
 647                         io->split_bio->bi_opf |= REQ_PREFLUSH;
 648                 if (io->has_fua)
 649                         io->split_bio->bi_opf |= REQ_FUA;
 650                 submit_bio(io->split_bio);
 651         }
 652 
 653         if (io->has_flush)
 654                 io->current_bio->bi_opf |= REQ_PREFLUSH;
 655         if (io->has_fua)
 656                 io->current_bio->bi_opf |= REQ_FUA;
 657         submit_bio(io->current_bio);
 658 }
 659 
 660 /* deferred io_unit will be dispatched here */
 661 static void r5l_submit_io_async(struct work_struct *work)
 662 {
 663         struct r5l_log *log = container_of(work, struct r5l_log,
 664                                            deferred_io_work);
 665         struct r5l_io_unit *io = NULL;
 666         unsigned long flags;
 667 
 668         spin_lock_irqsave(&log->io_list_lock, flags);
 669         if (!list_empty(&log->running_ios)) {
 670                 io = list_first_entry(&log->running_ios, struct r5l_io_unit,
 671                                       log_sibling);
 672                 if (!io->io_deferred)
 673                         io = NULL;
 674                 else
 675                         io->io_deferred = 0;
 676         }
 677         spin_unlock_irqrestore(&log->io_list_lock, flags);
 678         if (io)
 679                 r5l_do_submit_io(log, io);
 680 }
 681 
 682 static void r5c_disable_writeback_async(struct work_struct *work)
 683 {
 684         struct r5l_log *log = container_of(work, struct r5l_log,
 685                                            disable_writeback_work);
 686         struct mddev *mddev = log->rdev->mddev;
 687         struct r5conf *conf = mddev->private;
 688         int locked = 0;
 689 
 690         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
 691                 return;
 692         pr_info("md/raid:%s: Disabling writeback cache for degraded array.\n",
 693                 mdname(mddev));
 694 
 695         /* wait superblock change before suspend */
 696         wait_event(mddev->sb_wait,
 697                    conf->log == NULL ||
 698                    (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) &&
 699                     (locked = mddev_trylock(mddev))));
 700         if (locked) {
 701                 mddev_suspend(mddev);
 702                 log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
 703                 mddev_resume(mddev);
 704                 mddev_unlock(mddev);
 705         }
 706 }
 707 
 708 static void r5l_submit_current_io(struct r5l_log *log)
 709 {
 710         struct r5l_io_unit *io = log->current_io;
 711         struct r5l_meta_block *block;
 712         unsigned long flags;
 713         u32 crc;
 714         bool do_submit = true;
 715 
 716         if (!io)
 717                 return;
 718 
 719         block = page_address(io->meta_page);
 720         block->meta_size = cpu_to_le32(io->meta_offset);
 721         crc = crc32c_le(log->uuid_checksum, block, PAGE_SIZE);
 722         block->checksum = cpu_to_le32(crc);
 723 
 724         log->current_io = NULL;
 725         spin_lock_irqsave(&log->io_list_lock, flags);
 726         if (io->has_flush || io->has_fua) {
 727                 if (io != list_first_entry(&log->running_ios,
 728                                            struct r5l_io_unit, log_sibling)) {
 729                         io->io_deferred = 1;
 730                         do_submit = false;
 731                 }
 732         }
 733         spin_unlock_irqrestore(&log->io_list_lock, flags);
 734         if (do_submit)
 735                 r5l_do_submit_io(log, io);
 736 }
 737 
 738 static struct bio *r5l_bio_alloc(struct r5l_log *log)
 739 {
 740         struct bio *bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, &log->bs);
 741 
 742         bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 743         bio_set_dev(bio, log->rdev->bdev);
 744         bio->bi_iter.bi_sector = log->rdev->data_offset + log->log_start;
 745 
 746         return bio;
 747 }
 748 
 749 static void r5_reserve_log_entry(struct r5l_log *log, struct r5l_io_unit *io)
 750 {
 751         log->log_start = r5l_ring_add(log, log->log_start, BLOCK_SECTORS);
 752 
 753         r5c_update_log_state(log);
 754         /*
 755          * If we filled up the log device start from the beginning again,
 756          * which will require a new bio.
 757          *
 758          * Note: for this to work properly the log size needs to me a multiple
 759          * of BLOCK_SECTORS.
 760          */
 761         if (log->log_start == 0)
 762                 io->need_split_bio = true;
 763 
 764         io->log_end = log->log_start;
 765 }
 766 
 767 static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
 768 {
 769         struct r5l_io_unit *io;
 770         struct r5l_meta_block *block;
 771 
 772         io = mempool_alloc(&log->io_pool, GFP_ATOMIC);
 773         if (!io)
 774                 return NULL;
 775         memset(io, 0, sizeof(*io));
 776 
 777         io->log = log;
 778         INIT_LIST_HEAD(&io->log_sibling);
 779         INIT_LIST_HEAD(&io->stripe_list);
 780         bio_list_init(&io->flush_barriers);
 781         io->state = IO_UNIT_RUNNING;
 782 
 783         io->meta_page = mempool_alloc(&log->meta_pool, GFP_NOIO);
 784         block = page_address(io->meta_page);
 785         clear_page(block);
 786         block->magic = cpu_to_le32(R5LOG_MAGIC);
 787         block->version = R5LOG_VERSION;
 788         block->seq = cpu_to_le64(log->seq);
 789         block->position = cpu_to_le64(log->log_start);
 790 
 791         io->log_start = log->log_start;
 792         io->meta_offset = sizeof(struct r5l_meta_block);
 793         io->seq = log->seq++;
 794 
 795         io->current_bio = r5l_bio_alloc(log);
 796         io->current_bio->bi_end_io = r5l_log_endio;
 797         io->current_bio->bi_private = io;
 798         bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
 799 
 800         r5_reserve_log_entry(log, io);
 801 
 802         spin_lock_irq(&log->io_list_lock);
 803         list_add_tail(&io->log_sibling, &log->running_ios);
 804         spin_unlock_irq(&log->io_list_lock);
 805 
 806         return io;
 807 }
 808 
 809 static int r5l_get_meta(struct r5l_log *log, unsigned int payload_size)
 810 {
 811         if (log->current_io &&
 812             log->current_io->meta_offset + payload_size > PAGE_SIZE)
 813                 r5l_submit_current_io(log);
 814 
 815         if (!log->current_io) {
 816                 log->current_io = r5l_new_meta(log);
 817                 if (!log->current_io)
 818                         return -ENOMEM;
 819         }
 820 
 821         return 0;
 822 }
 823 
 824 static void r5l_append_payload_meta(struct r5l_log *log, u16 type,
 825                                     sector_t location,
 826                                     u32 checksum1, u32 checksum2,
 827                                     bool checksum2_valid)
 828 {
 829         struct r5l_io_unit *io = log->current_io;
 830         struct r5l_payload_data_parity *payload;
 831 
 832         payload = page_address(io->meta_page) + io->meta_offset;
 833         payload->header.type = cpu_to_le16(type);
 834         payload->header.flags = cpu_to_le16(0);
 835         payload->size = cpu_to_le32((1 + !!checksum2_valid) <<
 836                                     (PAGE_SHIFT - 9));
 837         payload->location = cpu_to_le64(location);
 838         payload->checksum[0] = cpu_to_le32(checksum1);
 839         if (checksum2_valid)
 840                 payload->checksum[1] = cpu_to_le32(checksum2);
 841 
 842         io->meta_offset += sizeof(struct r5l_payload_data_parity) +
 843                 sizeof(__le32) * (1 + !!checksum2_valid);
 844 }
 845 
 846 static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
 847 {
 848         struct r5l_io_unit *io = log->current_io;
 849 
 850         if (io->need_split_bio) {
 851                 BUG_ON(io->split_bio);
 852                 io->split_bio = io->current_bio;
 853                 io->current_bio = r5l_bio_alloc(log);
 854                 bio_chain(io->current_bio, io->split_bio);
 855                 io->need_split_bio = false;
 856         }
 857 
 858         if (!bio_add_page(io->current_bio, page, PAGE_SIZE, 0))
 859                 BUG();
 860 
 861         r5_reserve_log_entry(log, io);
 862 }
 863 
 864 static void r5l_append_flush_payload(struct r5l_log *log, sector_t sect)
 865 {
 866         struct mddev *mddev = log->rdev->mddev;
 867         struct r5conf *conf = mddev->private;
 868         struct r5l_io_unit *io;
 869         struct r5l_payload_flush *payload;
 870         int meta_size;
 871 
 872         /*
 873          * payload_flush requires extra writes to the journal.
 874          * To avoid handling the extra IO in quiesce, just skip
 875          * flush_payload
 876          */
 877         if (conf->quiesce)
 878                 return;
 879 
 880         mutex_lock(&log->io_mutex);
 881         meta_size = sizeof(struct r5l_payload_flush) + sizeof(__le64);
 882 
 883         if (r5l_get_meta(log, meta_size)) {
 884                 mutex_unlock(&log->io_mutex);
 885                 return;
 886         }
 887 
 888         /* current implementation is one stripe per flush payload */
 889         io = log->current_io;
 890         payload = page_address(io->meta_page) + io->meta_offset;
 891         payload->header.type = cpu_to_le16(R5LOG_PAYLOAD_FLUSH);
 892         payload->header.flags = cpu_to_le16(0);
 893         payload->size = cpu_to_le32(sizeof(__le64));
 894         payload->flush_stripes[0] = cpu_to_le64(sect);
 895         io->meta_offset += meta_size;
 896         /* multiple flush payloads count as one pending_stripe */
 897         if (!io->has_flush_payload) {
 898                 io->has_flush_payload = 1;
 899                 atomic_inc(&io->pending_stripe);
 900         }
 901         mutex_unlock(&log->io_mutex);
 902 }
 903 
 904 static int r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
 905                            int data_pages, int parity_pages)
 906 {
 907         int i;
 908         int meta_size;
 909         int ret;
 910         struct r5l_io_unit *io;
 911 
 912         meta_size =
 913                 ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
 914                  * data_pages) +
 915                 sizeof(struct r5l_payload_data_parity) +
 916                 sizeof(__le32) * parity_pages;
 917 
 918         ret = r5l_get_meta(log, meta_size);
 919         if (ret)
 920                 return ret;
 921 
 922         io = log->current_io;
 923 
 924         if (test_and_clear_bit(STRIPE_R5C_PREFLUSH, &sh->state))
 925                 io->has_flush = 1;
 926 
 927         for (i = 0; i < sh->disks; i++) {
 928                 if (!test_bit(R5_Wantwrite, &sh->dev[i].flags) ||
 929                     test_bit(R5_InJournal, &sh->dev[i].flags))
 930                         continue;
 931                 if (i == sh->pd_idx || i == sh->qd_idx)
 932                         continue;
 933                 if (test_bit(R5_WantFUA, &sh->dev[i].flags) &&
 934                     log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK) {
 935                         io->has_fua = 1;
 936                         /*
 937                          * we need to flush journal to make sure recovery can
 938                          * reach the data with fua flag
 939                          */
 940                         io->has_flush = 1;
 941                 }
 942                 r5l_append_payload_meta(log, R5LOG_PAYLOAD_DATA,
 943                                         raid5_compute_blocknr(sh, i, 0),
 944                                         sh->dev[i].log_checksum, 0, false);
 945                 r5l_append_payload_page(log, sh->dev[i].page);
 946         }
 947 
 948         if (parity_pages == 2) {
 949                 r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
 950                                         sh->sector, sh->dev[sh->pd_idx].log_checksum,
 951                                         sh->dev[sh->qd_idx].log_checksum, true);
 952                 r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
 953                 r5l_append_payload_page(log, sh->dev[sh->qd_idx].page);
 954         } else if (parity_pages == 1) {
 955                 r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
 956                                         sh->sector, sh->dev[sh->pd_idx].log_checksum,
 957                                         0, false);
 958                 r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
 959         } else  /* Just writing data, not parity, in caching phase */
 960                 BUG_ON(parity_pages != 0);
 961 
 962         list_add_tail(&sh->log_list, &io->stripe_list);
 963         atomic_inc(&io->pending_stripe);
 964         sh->log_io = io;
 965 
 966         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
 967                 return 0;
 968 
 969         if (sh->log_start == MaxSector) {
 970                 BUG_ON(!list_empty(&sh->r5c));
 971                 sh->log_start = io->log_start;
 972                 spin_lock_irq(&log->stripe_in_journal_lock);
 973                 list_add_tail(&sh->r5c,
 974                               &log->stripe_in_journal_list);
 975                 spin_unlock_irq(&log->stripe_in_journal_lock);
 976                 atomic_inc(&log->stripe_in_journal_count);
 977         }
 978         return 0;
 979 }
 980 
 981 /* add stripe to no_space_stripes, and then wake up reclaim */
 982 static inline void r5l_add_no_space_stripe(struct r5l_log *log,
 983                                            struct stripe_head *sh)
 984 {
 985         spin_lock(&log->no_space_stripes_lock);
 986         list_add_tail(&sh->log_list, &log->no_space_stripes);
 987         spin_unlock(&log->no_space_stripes_lock);
 988 }
 989 
 990 /*
 991  * running in raid5d, where reclaim could wait for raid5d too (when it flushes
 992  * data from log to raid disks), so we shouldn't wait for reclaim here
 993  */
 994 int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
 995 {
 996         struct r5conf *conf = sh->raid_conf;
 997         int write_disks = 0;
 998         int data_pages, parity_pages;
 999         int reserve;
1000         int i;
1001         int ret = 0;
1002         bool wake_reclaim = false;
1003 
1004         if (!log)
1005                 return -EAGAIN;
1006         /* Don't support stripe batch */
1007         if (sh->log_io || !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
1008             test_bit(STRIPE_SYNCING, &sh->state)) {
1009                 /* the stripe is written to log, we start writing it to raid */
1010                 clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
1011                 return -EAGAIN;
1012         }
1013 
1014         WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
1015 
1016         for (i = 0; i < sh->disks; i++) {
1017                 void *addr;
1018 
1019                 if (!test_bit(R5_Wantwrite, &sh->dev[i].flags) ||
1020                     test_bit(R5_InJournal, &sh->dev[i].flags))
1021                         continue;
1022 
1023                 write_disks++;
1024                 /* checksum is already calculated in last run */
1025                 if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
1026                         continue;
1027                 addr = kmap_atomic(sh->dev[i].page);
1028                 sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
1029                                                     addr, PAGE_SIZE);
1030                 kunmap_atomic(addr);
1031         }
1032         parity_pages = 1 + !!(sh->qd_idx >= 0);
1033         data_pages = write_disks - parity_pages;
1034 
1035         set_bit(STRIPE_LOG_TRAPPED, &sh->state);
1036         /*
1037          * The stripe must enter state machine again to finish the write, so
1038          * don't delay.
1039          */
1040         clear_bit(STRIPE_DELAYED, &sh->state);
1041         atomic_inc(&sh->count);
1042 
1043         mutex_lock(&log->io_mutex);
1044         /* meta + data */
1045         reserve = (1 + write_disks) << (PAGE_SHIFT - 9);
1046 
1047         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
1048                 if (!r5l_has_free_space(log, reserve)) {
1049                         r5l_add_no_space_stripe(log, sh);
1050                         wake_reclaim = true;
1051                 } else {
1052                         ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
1053                         if (ret) {
1054                                 spin_lock_irq(&log->io_list_lock);
1055                                 list_add_tail(&sh->log_list,
1056                                               &log->no_mem_stripes);
1057                                 spin_unlock_irq(&log->io_list_lock);
1058                         }
1059                 }
1060         } else {  /* R5C_JOURNAL_MODE_WRITE_BACK */
1061                 /*
1062                  * log space critical, do not process stripes that are
1063                  * not in cache yet (sh->log_start == MaxSector).
1064                  */
1065                 if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
1066                     sh->log_start == MaxSector) {
1067                         r5l_add_no_space_stripe(log, sh);
1068                         wake_reclaim = true;
1069                         reserve = 0;
1070                 } else if (!r5l_has_free_space(log, reserve)) {
1071                         if (sh->log_start == log->last_checkpoint)
1072                                 BUG();
1073                         else
1074                                 r5l_add_no_space_stripe(log, sh);
1075                 } else {
1076                         ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
1077                         if (ret) {
1078                                 spin_lock_irq(&log->io_list_lock);
1079                                 list_add_tail(&sh->log_list,
1080                                               &log->no_mem_stripes);
1081                                 spin_unlock_irq(&log->io_list_lock);
1082                         }
1083                 }
1084         }
1085 
1086         mutex_unlock(&log->io_mutex);
1087         if (wake_reclaim)
1088                 r5l_wake_reclaim(log, reserve);
1089         return 0;
1090 }
1091 
1092 void r5l_write_stripe_run(struct r5l_log *log)
1093 {
1094         if (!log)
1095                 return;
1096         mutex_lock(&log->io_mutex);
1097         r5l_submit_current_io(log);
1098         mutex_unlock(&log->io_mutex);
1099 }
1100 
1101 int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio)
1102 {
1103         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
1104                 /*
1105                  * in write through (journal only)
1106                  * we flush log disk cache first, then write stripe data to
1107                  * raid disks. So if bio is finished, the log disk cache is
1108                  * flushed already. The recovery guarantees we can recovery
1109                  * the bio from log disk, so we don't need to flush again
1110                  */
1111                 if (bio->bi_iter.bi_size == 0) {
1112                         bio_endio(bio);
1113                         return 0;
1114                 }
1115                 bio->bi_opf &= ~REQ_PREFLUSH;
1116         } else {
1117                 /* write back (with cache) */
1118                 if (bio->bi_iter.bi_size == 0) {
1119                         mutex_lock(&log->io_mutex);
1120                         r5l_get_meta(log, 0);
1121                         bio_list_add(&log->current_io->flush_barriers, bio);
1122                         log->current_io->has_flush = 1;
1123                         log->current_io->has_null_flush = 1;
1124                         atomic_inc(&log->current_io->pending_stripe);
1125                         r5l_submit_current_io(log);
1126                         mutex_unlock(&log->io_mutex);
1127                         return 0;
1128                 }
1129         }
1130         return -EAGAIN;
1131 }
1132 
1133 /* This will run after log space is reclaimed */
1134 static void r5l_run_no_space_stripes(struct r5l_log *log)
1135 {
1136         struct stripe_head *sh;
1137 
1138         spin_lock(&log->no_space_stripes_lock);
1139         while (!list_empty(&log->no_space_stripes)) {
1140                 sh = list_first_entry(&log->no_space_stripes,
1141                                       struct stripe_head, log_list);
1142                 list_del_init(&sh->log_list);
1143                 set_bit(STRIPE_HANDLE, &sh->state);
1144                 raid5_release_stripe(sh);
1145         }
1146         spin_unlock(&log->no_space_stripes_lock);
1147 }
1148 
1149 /*
1150  * calculate new last_checkpoint
1151  * for write through mode, returns log->next_checkpoint
1152  * for write back, returns log_start of first sh in stripe_in_journal_list
1153  */
1154 static sector_t r5c_calculate_new_cp(struct r5conf *conf)
1155 {
1156         struct stripe_head *sh;
1157         struct r5l_log *log = conf->log;
1158         sector_t new_cp;
1159         unsigned long flags;
1160 
1161         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
1162                 return log->next_checkpoint;
1163 
1164         spin_lock_irqsave(&log->stripe_in_journal_lock, flags);
1165         if (list_empty(&conf->log->stripe_in_journal_list)) {
1166                 /* all stripes flushed */
1167                 spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
1168                 return log->next_checkpoint;
1169         }
1170         sh = list_first_entry(&conf->log->stripe_in_journal_list,
1171                               struct stripe_head, r5c);
1172         new_cp = sh->log_start;
1173         spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
1174         return new_cp;
1175 }
1176 
1177 static sector_t r5l_reclaimable_space(struct r5l_log *log)
1178 {
1179         struct r5conf *conf = log->rdev->mddev->private;
1180 
1181         return r5l_ring_distance(log, log->last_checkpoint,
1182                                  r5c_calculate_new_cp(conf));
1183 }
1184 
1185 static void r5l_run_no_mem_stripe(struct r5l_log *log)
1186 {
1187         struct stripe_head *sh;
1188 
1189         lockdep_assert_held(&log->io_list_lock);
1190 
1191         if (!list_empty(&log->no_mem_stripes)) {
1192                 sh = list_first_entry(&log->no_mem_stripes,
1193                                       struct stripe_head, log_list);
1194                 list_del_init(&sh->log_list);
1195                 set_bit(STRIPE_HANDLE, &sh->state);
1196                 raid5_release_stripe(sh);
1197         }
1198 }
1199 
1200 static bool r5l_complete_finished_ios(struct r5l_log *log)
1201 {
1202         struct r5l_io_unit *io, *next;
1203         bool found = false;
1204 
1205         lockdep_assert_held(&log->io_list_lock);
1206 
1207         list_for_each_entry_safe(io, next, &log->finished_ios, log_sibling) {
1208                 /* don't change list order */
1209                 if (io->state < IO_UNIT_STRIPE_END)
1210                         break;
1211 
1212                 log->next_checkpoint = io->log_start;
1213 
1214                 list_del(&io->log_sibling);
1215                 mempool_free(io, &log->io_pool);
1216                 r5l_run_no_mem_stripe(log);
1217 
1218                 found = true;
1219         }
1220 
1221         return found;
1222 }
1223 
1224 static void __r5l_stripe_write_finished(struct r5l_io_unit *io)
1225 {
1226         struct r5l_log *log = io->log;
1227         struct r5conf *conf = log->rdev->mddev->private;
1228         unsigned long flags;
1229 
1230         spin_lock_irqsave(&log->io_list_lock, flags);
1231         __r5l_set_io_unit_state(io, IO_UNIT_STRIPE_END);
1232 
1233         if (!r5l_complete_finished_ios(log)) {
1234                 spin_unlock_irqrestore(&log->io_list_lock, flags);
1235                 return;
1236         }
1237 
1238         if (r5l_reclaimable_space(log) > log->max_free_space ||
1239             test_bit(R5C_LOG_TIGHT, &conf->cache_state))
1240                 r5l_wake_reclaim(log, 0);
1241 
1242         spin_unlock_irqrestore(&log->io_list_lock, flags);
1243         wake_up(&log->iounit_wait);
1244 }
1245 
1246 void r5l_stripe_write_finished(struct stripe_head *sh)
1247 {
1248         struct r5l_io_unit *io;
1249 
1250         io = sh->log_io;
1251         sh->log_io = NULL;
1252 
1253         if (io && atomic_dec_and_test(&io->pending_stripe))
1254                 __r5l_stripe_write_finished(io);
1255 }
1256 
1257 static void r5l_log_flush_endio(struct bio *bio)
1258 {
1259         struct r5l_log *log = container_of(bio, struct r5l_log,
1260                 flush_bio);
1261         unsigned long flags;
1262         struct r5l_io_unit *io;
1263 
1264         if (bio->bi_status)
1265                 md_error(log->rdev->mddev, log->rdev);
1266 
1267         spin_lock_irqsave(&log->io_list_lock, flags);
1268         list_for_each_entry(io, &log->flushing_ios, log_sibling)
1269                 r5l_io_run_stripes(io);
1270         list_splice_tail_init(&log->flushing_ios, &log->finished_ios);
1271         spin_unlock_irqrestore(&log->io_list_lock, flags);
1272 }
1273 
1274 /*
1275  * Starting dispatch IO to raid.
1276  * io_unit(meta) consists of a log. There is one situation we want to avoid. A
1277  * broken meta in the middle of a log causes recovery can't find meta at the
1278  * head of log. If operations require meta at the head persistent in log, we
1279  * must make sure meta before it persistent in log too. A case is:
1280  *
1281  * stripe data/parity is in log, we start write stripe to raid disks. stripe
1282  * data/parity must be persistent in log before we do the write to raid disks.
1283  *
1284  * The solution is we restrictly maintain io_unit list order. In this case, we
1285  * only write stripes of an io_unit to raid disks till the io_unit is the first
1286  * one whose data/parity is in log.
1287  */
1288 void r5l_flush_stripe_to_raid(struct r5l_log *log)
1289 {
1290         bool do_flush;
1291 
1292         if (!log || !log->need_cache_flush)
1293                 return;
1294 
1295         spin_lock_irq(&log->io_list_lock);
1296         /* flush bio is running */
1297         if (!list_empty(&log->flushing_ios)) {
1298                 spin_unlock_irq(&log->io_list_lock);
1299                 return;
1300         }
1301         list_splice_tail_init(&log->io_end_ios, &log->flushing_ios);
1302         do_flush = !list_empty(&log->flushing_ios);
1303         spin_unlock_irq(&log->io_list_lock);
1304 
1305         if (!do_flush)
1306                 return;
1307         bio_reset(&log->flush_bio);
1308         bio_set_dev(&log->flush_bio, log->rdev->bdev);
1309         log->flush_bio.bi_end_io = r5l_log_flush_endio;
1310         log->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
1311         submit_bio(&log->flush_bio);
1312 }
1313 
1314 static void r5l_write_super(struct r5l_log *log, sector_t cp);
1315 static void r5l_write_super_and_discard_space(struct r5l_log *log,
1316         sector_t end)
1317 {
1318         struct block_device *bdev = log->rdev->bdev;
1319         struct mddev *mddev;
1320 
1321         r5l_write_super(log, end);
1322 
1323         if (!blk_queue_discard(bdev_get_queue(bdev)))
1324                 return;
1325 
1326         mddev = log->rdev->mddev;
1327         /*
1328          * Discard could zero data, so before discard we must make sure
1329          * superblock is updated to new log tail. Updating superblock (either
1330          * directly call md_update_sb() or depend on md thread) must hold
1331          * reconfig mutex. On the other hand, raid5_quiesce is called with
1332          * reconfig_mutex hold. The first step of raid5_quiesce() is waitting
1333          * for all IO finish, hence waitting for reclaim thread, while reclaim
1334          * thread is calling this function and waitting for reconfig mutex. So
1335          * there is a deadlock. We workaround this issue with a trylock.
1336          * FIXME: we could miss discard if we can't take reconfig mutex
1337          */
1338         set_mask_bits(&mddev->sb_flags, 0,
1339                 BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
1340         if (!mddev_trylock(mddev))
1341                 return;
1342         md_update_sb(mddev, 1);
1343         mddev_unlock(mddev);
1344 
1345         /* discard IO error really doesn't matter, ignore it */
1346         if (log->last_checkpoint < end) {
1347                 blkdev_issue_discard(bdev,
1348                                 log->last_checkpoint + log->rdev->data_offset,
1349                                 end - log->last_checkpoint, GFP_NOIO, 0);
1350         } else {
1351                 blkdev_issue_discard(bdev,
1352                                 log->last_checkpoint + log->rdev->data_offset,
1353                                 log->device_size - log->last_checkpoint,
1354                                 GFP_NOIO, 0);
1355                 blkdev_issue_discard(bdev, log->rdev->data_offset, end,
1356                                 GFP_NOIO, 0);
1357         }
1358 }
1359 
1360 /*
1361  * r5c_flush_stripe moves stripe from cached list to handle_list. When called,
1362  * the stripe must be on r5c_cached_full_stripes or r5c_cached_partial_stripes.
1363  *
1364  * must hold conf->device_lock
1365  */
1366 static void r5c_flush_stripe(struct r5conf *conf, struct stripe_head *sh)
1367 {
1368         BUG_ON(list_empty(&sh->lru));
1369         BUG_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
1370         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
1371 
1372         /*
1373          * The stripe is not ON_RELEASE_LIST, so it is safe to call
1374          * raid5_release_stripe() while holding conf->device_lock
1375          */
1376         BUG_ON(test_bit(STRIPE_ON_RELEASE_LIST, &sh->state));
1377         lockdep_assert_held(&conf->device_lock);
1378 
1379         list_del_init(&sh->lru);
1380         atomic_inc(&sh->count);
1381 
1382         set_bit(STRIPE_HANDLE, &sh->state);
1383         atomic_inc(&conf->active_stripes);
1384         r5c_make_stripe_write_out(sh);
1385 
1386         if (test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
1387                 atomic_inc(&conf->r5c_flushing_partial_stripes);
1388         else
1389                 atomic_inc(&conf->r5c_flushing_full_stripes);
1390         raid5_release_stripe(sh);
1391 }
1392 
1393 /*
1394  * if num == 0, flush all full stripes
1395  * if num > 0, flush all full stripes. If less than num full stripes are
1396  *             flushed, flush some partial stripes until totally num stripes are
1397  *             flushed or there is no more cached stripes.
1398  */
1399 void r5c_flush_cache(struct r5conf *conf, int num)
1400 {
1401         int count;
1402         struct stripe_head *sh, *next;
1403 
1404         lockdep_assert_held(&conf->device_lock);
1405         if (!conf->log)
1406                 return;
1407 
1408         count = 0;
1409         list_for_each_entry_safe(sh, next, &conf->r5c_full_stripe_list, lru) {
1410                 r5c_flush_stripe(conf, sh);
1411                 count++;
1412         }
1413 
1414         if (count >= num)
1415                 return;
1416         list_for_each_entry_safe(sh, next,
1417                                  &conf->r5c_partial_stripe_list, lru) {
1418                 r5c_flush_stripe(conf, sh);
1419                 if (++count >= num)
1420                         break;
1421         }
1422 }
1423 
1424 static void r5c_do_reclaim(struct r5conf *conf)
1425 {
1426         struct r5l_log *log = conf->log;
1427         struct stripe_head *sh;
1428         int count = 0;
1429         unsigned long flags;
1430         int total_cached;
1431         int stripes_to_flush;
1432         int flushing_partial, flushing_full;
1433 
1434         if (!r5c_is_writeback(log))
1435                 return;
1436 
1437         flushing_partial = atomic_read(&conf->r5c_flushing_partial_stripes);
1438         flushing_full = atomic_read(&conf->r5c_flushing_full_stripes);
1439         total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
1440                 atomic_read(&conf->r5c_cached_full_stripes) -
1441                 flushing_full - flushing_partial;
1442 
1443         if (total_cached > conf->min_nr_stripes * 3 / 4 ||
1444             atomic_read(&conf->empty_inactive_list_nr) > 0)
1445                 /*
1446                  * if stripe cache pressure high, flush all full stripes and
1447                  * some partial stripes
1448                  */
1449                 stripes_to_flush = R5C_RECLAIM_STRIPE_GROUP;
1450         else if (total_cached > conf->min_nr_stripes * 1 / 2 ||
1451                  atomic_read(&conf->r5c_cached_full_stripes) - flushing_full >
1452                  R5C_FULL_STRIPE_FLUSH_BATCH(conf))
1453                 /*
1454                  * if stripe cache pressure moderate, or if there is many full
1455                  * stripes,flush all full stripes
1456                  */
1457                 stripes_to_flush = 0;
1458         else
1459                 /* no need to flush */
1460                 stripes_to_flush = -1;
1461 
1462         if (stripes_to_flush >= 0) {
1463                 spin_lock_irqsave(&conf->device_lock, flags);
1464                 r5c_flush_cache(conf, stripes_to_flush);
1465                 spin_unlock_irqrestore(&conf->device_lock, flags);
1466         }
1467 
1468         /* if log space is tight, flush stripes on stripe_in_journal_list */
1469         if (test_bit(R5C_LOG_TIGHT, &conf->cache_state)) {
1470                 spin_lock_irqsave(&log->stripe_in_journal_lock, flags);
1471                 spin_lock(&conf->device_lock);
1472                 list_for_each_entry(sh, &log->stripe_in_journal_list, r5c) {
1473                         /*
1474                          * stripes on stripe_in_journal_list could be in any
1475                          * state of the stripe_cache state machine. In this
1476                          * case, we only want to flush stripe on
1477                          * r5c_cached_full/partial_stripes. The following
1478                          * condition makes sure the stripe is on one of the
1479                          * two lists.
1480                          */
1481                         if (!list_empty(&sh->lru) &&
1482                             !test_bit(STRIPE_HANDLE, &sh->state) &&
1483                             atomic_read(&sh->count) == 0) {
1484                                 r5c_flush_stripe(conf, sh);
1485                                 if (count++ >= R5C_RECLAIM_STRIPE_GROUP)
1486                                         break;
1487                         }
1488                 }
1489                 spin_unlock(&conf->device_lock);
1490                 spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
1491         }
1492 
1493         if (!test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
1494                 r5l_run_no_space_stripes(log);
1495 
1496         md_wakeup_thread(conf->mddev->thread);
1497 }
1498 
1499 static void r5l_do_reclaim(struct r5l_log *log)
1500 {
1501         struct r5conf *conf = log->rdev->mddev->private;
1502         sector_t reclaim_target = xchg(&log->reclaim_target, 0);
1503         sector_t reclaimable;
1504         sector_t next_checkpoint;
1505         bool write_super;
1506 
1507         spin_lock_irq(&log->io_list_lock);
1508         write_super = r5l_reclaimable_space(log) > log->max_free_space ||
1509                 reclaim_target != 0 || !list_empty(&log->no_space_stripes);
1510         /*
1511          * move proper io_unit to reclaim list. We should not change the order.
1512          * reclaimable/unreclaimable io_unit can be mixed in the list, we
1513          * shouldn't reuse space of an unreclaimable io_unit
1514          */
1515         while (1) {
1516                 reclaimable = r5l_reclaimable_space(log);
1517                 if (reclaimable >= reclaim_target ||
1518                     (list_empty(&log->running_ios) &&
1519                      list_empty(&log->io_end_ios) &&
1520                      list_empty(&log->flushing_ios) &&
1521                      list_empty(&log->finished_ios)))
1522                         break;
1523 
1524                 md_wakeup_thread(log->rdev->mddev->thread);
1525                 wait_event_lock_irq(log->iounit_wait,
1526                                     r5l_reclaimable_space(log) > reclaimable,
1527                                     log->io_list_lock);
1528         }
1529 
1530         next_checkpoint = r5c_calculate_new_cp(conf);
1531         spin_unlock_irq(&log->io_list_lock);
1532 
1533         if (reclaimable == 0 || !write_super)
1534                 return;
1535 
1536         /*
1537          * write_super will flush cache of each raid disk. We must write super
1538          * here, because the log area might be reused soon and we don't want to
1539          * confuse recovery
1540          */
1541         r5l_write_super_and_discard_space(log, next_checkpoint);
1542 
1543         mutex_lock(&log->io_mutex);
1544         log->last_checkpoint = next_checkpoint;
1545         r5c_update_log_state(log);
1546         mutex_unlock(&log->io_mutex);
1547 
1548         r5l_run_no_space_stripes(log);
1549 }
1550 
1551 static void r5l_reclaim_thread(struct md_thread *thread)
1552 {
1553         struct mddev *mddev = thread->mddev;
1554         struct r5conf *conf = mddev->private;
1555         struct r5l_log *log = conf->log;
1556 
1557         if (!log)
1558                 return;
1559         r5c_do_reclaim(conf);
1560         r5l_do_reclaim(log);
1561 }
1562 
1563 void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
1564 {
1565         unsigned long target;
1566         unsigned long new = (unsigned long)space; /* overflow in theory */
1567 
1568         if (!log)
1569                 return;
1570         do {
1571                 target = log->reclaim_target;
1572                 if (new < target)
1573                         return;
1574         } while (cmpxchg(&log->reclaim_target, target, new) != target);
1575         md_wakeup_thread(log->reclaim_thread);
1576 }
1577 
1578 void r5l_quiesce(struct r5l_log *log, int quiesce)
1579 {
1580         struct mddev *mddev;
1581 
1582         if (quiesce) {
1583                 /* make sure r5l_write_super_and_discard_space exits */
1584                 mddev = log->rdev->mddev;
1585                 wake_up(&mddev->sb_wait);
1586                 kthread_park(log->reclaim_thread->tsk);
1587                 r5l_wake_reclaim(log, MaxSector);
1588                 r5l_do_reclaim(log);
1589         } else
1590                 kthread_unpark(log->reclaim_thread->tsk);
1591 }
1592 
1593 bool r5l_log_disk_error(struct r5conf *conf)
1594 {
1595         struct r5l_log *log;
1596         bool ret;
1597         /* don't allow write if journal disk is missing */
1598         rcu_read_lock();
1599         log = rcu_dereference(conf->log);
1600 
1601         if (!log)
1602                 ret = test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
1603         else
1604                 ret = test_bit(Faulty, &log->rdev->flags);
1605         rcu_read_unlock();
1606         return ret;
1607 }
1608 
1609 #define R5L_RECOVERY_PAGE_POOL_SIZE 256
1610 
1611 struct r5l_recovery_ctx {
1612         struct page *meta_page;         /* current meta */
1613         sector_t meta_total_blocks;     /* total size of current meta and data */
1614         sector_t pos;                   /* recovery position */
1615         u64 seq;                        /* recovery position seq */
1616         int data_parity_stripes;        /* number of data_parity stripes */
1617         int data_only_stripes;          /* number of data_only stripes */
1618         struct list_head cached_list;
1619 
1620         /*
1621          * read ahead page pool (ra_pool)
1622          * in recovery, log is read sequentially. It is not efficient to
1623          * read every page with sync_page_io(). The read ahead page pool
1624          * reads multiple pages with one IO, so further log read can
1625          * just copy data from the pool.
1626          */
1627         struct page *ra_pool[R5L_RECOVERY_PAGE_POOL_SIZE];
1628         sector_t pool_offset;   /* offset of first page in the pool */
1629         int total_pages;        /* total allocated pages */
1630         int valid_pages;        /* pages with valid data */
1631         struct bio *ra_bio;     /* bio to do the read ahead */
1632 };
1633 
1634 static int r5l_recovery_allocate_ra_pool(struct r5l_log *log,
1635                                             struct r5l_recovery_ctx *ctx)
1636 {
1637         struct page *page;
1638 
1639         ctx->ra_bio = bio_alloc_bioset(GFP_KERNEL, BIO_MAX_PAGES, &log->bs);
1640         if (!ctx->ra_bio)
1641                 return -ENOMEM;
1642 
1643         ctx->valid_pages = 0;
1644         ctx->total_pages = 0;
1645         while (ctx->total_pages < R5L_RECOVERY_PAGE_POOL_SIZE) {
1646                 page = alloc_page(GFP_KERNEL);
1647 
1648                 if (!page)
1649                         break;
1650                 ctx->ra_pool[ctx->total_pages] = page;
1651                 ctx->total_pages += 1;
1652         }
1653 
1654         if (ctx->total_pages == 0) {
1655                 bio_put(ctx->ra_bio);
1656                 return -ENOMEM;
1657         }
1658 
1659         ctx->pool_offset = 0;
1660         return 0;
1661 }
1662 
1663 static void r5l_recovery_free_ra_pool(struct r5l_log *log,
1664                                         struct r5l_recovery_ctx *ctx)
1665 {
1666         int i;
1667 
1668         for (i = 0; i < ctx->total_pages; ++i)
1669                 put_page(ctx->ra_pool[i]);
1670         bio_put(ctx->ra_bio);
1671 }
1672 
1673 /*
1674  * fetch ctx->valid_pages pages from offset
1675  * In normal cases, ctx->valid_pages == ctx->total_pages after the call.
1676  * However, if the offset is close to the end of the journal device,
1677  * ctx->valid_pages could be smaller than ctx->total_pages
1678  */
1679 static int r5l_recovery_fetch_ra_pool(struct r5l_log *log,
1680                                       struct r5l_recovery_ctx *ctx,
1681                                       sector_t offset)
1682 {
1683         bio_reset(ctx->ra_bio);
1684         bio_set_dev(ctx->ra_bio, log->rdev->bdev);
1685         bio_set_op_attrs(ctx->ra_bio, REQ_OP_READ, 0);
1686         ctx->ra_bio->bi_iter.bi_sector = log->rdev->data_offset + offset;
1687 
1688         ctx->valid_pages = 0;
1689         ctx->pool_offset = offset;
1690 
1691         while (ctx->valid_pages < ctx->total_pages) {
1692                 bio_add_page(ctx->ra_bio,
1693                              ctx->ra_pool[ctx->valid_pages], PAGE_SIZE, 0);
1694                 ctx->valid_pages += 1;
1695 
1696                 offset = r5l_ring_add(log, offset, BLOCK_SECTORS);
1697 
1698                 if (offset == 0)  /* reached end of the device */
1699                         break;
1700         }
1701 
1702         return submit_bio_wait(ctx->ra_bio);
1703 }
1704 
1705 /*
1706  * try read a page from the read ahead page pool, if the page is not in the
1707  * pool, call r5l_recovery_fetch_ra_pool
1708  */
1709 static int r5l_recovery_read_page(struct r5l_log *log,
1710                                   struct r5l_recovery_ctx *ctx,
1711                                   struct page *page,
1712                                   sector_t offset)
1713 {
1714         int ret;
1715 
1716         if (offset < ctx->pool_offset ||
1717             offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS) {
1718                 ret = r5l_recovery_fetch_ra_pool(log, ctx, offset);
1719                 if (ret)
1720                         return ret;
1721         }
1722 
1723         BUG_ON(offset < ctx->pool_offset ||
1724                offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS);
1725 
1726         memcpy(page_address(page),
1727                page_address(ctx->ra_pool[(offset - ctx->pool_offset) >>
1728                                          BLOCK_SECTOR_SHIFT]),
1729                PAGE_SIZE);
1730         return 0;
1731 }
1732 
1733 static int r5l_recovery_read_meta_block(struct r5l_log *log,
1734                                         struct r5l_recovery_ctx *ctx)
1735 {
1736         struct page *page = ctx->meta_page;
1737         struct r5l_meta_block *mb;
1738         u32 crc, stored_crc;
1739         int ret;
1740 
1741         ret = r5l_recovery_read_page(log, ctx, page, ctx->pos);
1742         if (ret != 0)
1743                 return ret;
1744 
1745         mb = page_address(page);
1746         stored_crc = le32_to_cpu(mb->checksum);
1747         mb->checksum = 0;
1748 
1749         if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
1750             le64_to_cpu(mb->seq) != ctx->seq ||
1751             mb->version != R5LOG_VERSION ||
1752             le64_to_cpu(mb->position) != ctx->pos)
1753                 return -EINVAL;
1754 
1755         crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
1756         if (stored_crc != crc)
1757                 return -EINVAL;
1758 
1759         if (le32_to_cpu(mb->meta_size) > PAGE_SIZE)
1760                 return -EINVAL;
1761 
1762         ctx->meta_total_blocks = BLOCK_SECTORS;
1763 
1764         return 0;
1765 }
1766 
1767 static void
1768 r5l_recovery_create_empty_meta_block(struct r5l_log *log,
1769                                      struct page *page,
1770                                      sector_t pos, u64 seq)
1771 {
1772         struct r5l_meta_block *mb;
1773 
1774         mb = page_address(page);
1775         clear_page(mb);
1776         mb->magic = cpu_to_le32(R5LOG_MAGIC);
1777         mb->version = R5LOG_VERSION;
1778         mb->meta_size = cpu_to_le32(sizeof(struct r5l_meta_block));
1779         mb->seq = cpu_to_le64(seq);
1780         mb->position = cpu_to_le64(pos);
1781 }
1782 
1783 static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
1784                                           u64 seq)
1785 {
1786         struct page *page;
1787         struct r5l_meta_block *mb;
1788 
1789         page = alloc_page(GFP_KERNEL);
1790         if (!page)
1791                 return -ENOMEM;
1792         r5l_recovery_create_empty_meta_block(log, page, pos, seq);
1793         mb = page_address(page);
1794         mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
1795                                              mb, PAGE_SIZE));
1796         if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, REQ_OP_WRITE,
1797                           REQ_SYNC | REQ_FUA, false)) {
1798                 __free_page(page);
1799                 return -EIO;
1800         }
1801         __free_page(page);
1802         return 0;
1803 }
1804 
1805 /*
1806  * r5l_recovery_load_data and r5l_recovery_load_parity uses flag R5_Wantwrite
1807  * to mark valid (potentially not flushed) data in the journal.
1808  *
1809  * We already verified checksum in r5l_recovery_verify_data_checksum_for_mb,
1810  * so there should not be any mismatch here.
1811  */
1812 static void r5l_recovery_load_data(struct r5l_log *log,
1813                                    struct stripe_head *sh,
1814                                    struct r5l_recovery_ctx *ctx,
1815                                    struct r5l_payload_data_parity *payload,
1816                                    sector_t log_offset)
1817 {
1818         struct mddev *mddev = log->rdev->mddev;
1819         struct r5conf *conf = mddev->private;
1820         int dd_idx;
1821 
1822         raid5_compute_sector(conf,
1823                              le64_to_cpu(payload->location), 0,
1824                              &dd_idx, sh);
1825         r5l_recovery_read_page(log, ctx, sh->dev[dd_idx].page, log_offset);
1826         sh->dev[dd_idx].log_checksum =
1827                 le32_to_cpu(payload->checksum[0]);
1828         ctx->meta_total_blocks += BLOCK_SECTORS;
1829 
1830         set_bit(R5_Wantwrite, &sh->dev[dd_idx].flags);
1831         set_bit(STRIPE_R5C_CACHING, &sh->state);
1832 }
1833 
1834 static void r5l_recovery_load_parity(struct r5l_log *log,
1835                                      struct stripe_head *sh,
1836                                      struct r5l_recovery_ctx *ctx,
1837                                      struct r5l_payload_data_parity *payload,
1838                                      sector_t log_offset)
1839 {
1840         struct mddev *mddev = log->rdev->mddev;
1841         struct r5conf *conf = mddev->private;
1842 
1843         ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded;
1844         r5l_recovery_read_page(log, ctx, sh->dev[sh->pd_idx].page, log_offset);
1845         sh->dev[sh->pd_idx].log_checksum =
1846                 le32_to_cpu(payload->checksum[0]);
1847         set_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags);
1848 
1849         if (sh->qd_idx >= 0) {
1850                 r5l_recovery_read_page(
1851                         log, ctx, sh->dev[sh->qd_idx].page,
1852                         r5l_ring_add(log, log_offset, BLOCK_SECTORS));
1853                 sh->dev[sh->qd_idx].log_checksum =
1854                         le32_to_cpu(payload->checksum[1]);
1855                 set_bit(R5_Wantwrite, &sh->dev[sh->qd_idx].flags);
1856         }
1857         clear_bit(STRIPE_R5C_CACHING, &sh->state);
1858 }
1859 
1860 static void r5l_recovery_reset_stripe(struct stripe_head *sh)
1861 {
1862         int i;
1863 
1864         sh->state = 0;
1865         sh->log_start = MaxSector;
1866         for (i = sh->disks; i--; )
1867                 sh->dev[i].flags = 0;
1868 }
1869 
1870 static void
1871 r5l_recovery_replay_one_stripe(struct r5conf *conf,
1872                                struct stripe_head *sh,
1873                                struct r5l_recovery_ctx *ctx)
1874 {
1875         struct md_rdev *rdev, *rrdev;
1876         int disk_index;
1877         int data_count = 0;
1878 
1879         for (disk_index = 0; disk_index < sh->disks; disk_index++) {
1880                 if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
1881                         continue;
1882                 if (disk_index == sh->qd_idx || disk_index == sh->pd_idx)
1883                         continue;
1884                 data_count++;
1885         }
1886 
1887         /*
1888          * stripes that only have parity must have been flushed
1889          * before the crash that we are now recovering from, so
1890          * there is nothing more to recovery.
1891          */
1892         if (data_count == 0)
1893                 goto out;
1894 
1895         for (disk_index = 0; disk_index < sh->disks; disk_index++) {
1896                 if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
1897                         continue;
1898 
1899                 /* in case device is broken */
1900                 rcu_read_lock();
1901                 rdev = rcu_dereference(conf->disks[disk_index].rdev);
1902                 if (rdev) {
1903                         atomic_inc(&rdev->nr_pending);
1904                         rcu_read_unlock();
1905                         sync_page_io(rdev, sh->sector, PAGE_SIZE,
1906                                      sh->dev[disk_index].page, REQ_OP_WRITE, 0,
1907                                      false);
1908                         rdev_dec_pending(rdev, rdev->mddev);
1909                         rcu_read_lock();
1910                 }
1911                 rrdev = rcu_dereference(conf->disks[disk_index].replacement);
1912                 if (rrdev) {
1913                         atomic_inc(&rrdev->nr_pending);
1914                         rcu_read_unlock();
1915                         sync_page_io(rrdev, sh->sector, PAGE_SIZE,
1916                                      sh->dev[disk_index].page, REQ_OP_WRITE, 0,
1917                                      false);
1918                         rdev_dec_pending(rrdev, rrdev->mddev);
1919                         rcu_read_lock();
1920                 }
1921                 rcu_read_unlock();
1922         }
1923         ctx->data_parity_stripes++;
1924 out:
1925         r5l_recovery_reset_stripe(sh);
1926 }
1927 
1928 static struct stripe_head *
1929 r5c_recovery_alloc_stripe(
1930                 struct r5conf *conf,
1931                 sector_t stripe_sect,
1932                 int noblock)
1933 {
1934         struct stripe_head *sh;
1935 
1936         sh = raid5_get_active_stripe(conf, stripe_sect, 0, noblock, 0);
1937         if (!sh)
1938                 return NULL;  /* no more stripe available */
1939 
1940         r5l_recovery_reset_stripe(sh);
1941 
1942         return sh;
1943 }
1944 
1945 static struct stripe_head *
1946 r5c_recovery_lookup_stripe(struct list_head *list, sector_t sect)
1947 {
1948         struct stripe_head *sh;
1949 
1950         list_for_each_entry(sh, list, lru)
1951                 if (sh->sector == sect)
1952                         return sh;
1953         return NULL;
1954 }
1955 
1956 static void
1957 r5c_recovery_drop_stripes(struct list_head *cached_stripe_list,
1958                           struct r5l_recovery_ctx *ctx)
1959 {
1960         struct stripe_head *sh, *next;
1961 
1962         list_for_each_entry_safe(sh, next, cached_stripe_list, lru) {
1963                 r5l_recovery_reset_stripe(sh);
1964                 list_del_init(&sh->lru);
1965                 raid5_release_stripe(sh);
1966         }
1967 }
1968 
1969 static void
1970 r5c_recovery_replay_stripes(struct list_head *cached_stripe_list,
1971                             struct r5l_recovery_ctx *ctx)
1972 {
1973         struct stripe_head *sh, *next;
1974 
1975         list_for_each_entry_safe(sh, next, cached_stripe_list, lru)
1976                 if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
1977                         r5l_recovery_replay_one_stripe(sh->raid_conf, sh, ctx);
1978                         list_del_init(&sh->lru);
1979                         raid5_release_stripe(sh);
1980                 }
1981 }
1982 
1983 /* if matches return 0; otherwise return -EINVAL */
1984 static int
1985 r5l_recovery_verify_data_checksum(struct r5l_log *log,
1986                                   struct r5l_recovery_ctx *ctx,
1987                                   struct page *page,
1988                                   sector_t log_offset, __le32 log_checksum)
1989 {
1990         void *addr;
1991         u32 checksum;
1992 
1993         r5l_recovery_read_page(log, ctx, page, log_offset);
1994         addr = kmap_atomic(page);
1995         checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
1996         kunmap_atomic(addr);
1997         return (le32_to_cpu(log_checksum) == checksum) ? 0 : -EINVAL;
1998 }
1999 
2000 /*
2001  * before loading data to stripe cache, we need verify checksum for all data,
2002  * if there is mismatch for any data page, we drop all data in the mata block
2003  */
2004 static int
2005 r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log,
2006                                          struct r5l_recovery_ctx *ctx)
2007 {
2008         struct mddev *mddev = log->rdev->mddev;
2009         struct r5conf *conf = mddev->private;
2010         struct r5l_meta_block *mb = page_address(ctx->meta_page);
2011         sector_t mb_offset = sizeof(struct r5l_meta_block);
2012         sector_t log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
2013         struct page *page;
2014         struct r5l_payload_data_parity *payload;
2015         struct r5l_payload_flush *payload_flush;
2016 
2017         page = alloc_page(GFP_KERNEL);
2018         if (!page)
2019                 return -ENOMEM;
2020 
2021         while (mb_offset < le32_to_cpu(mb->meta_size)) {
2022                 payload = (void *)mb + mb_offset;
2023                 payload_flush = (void *)mb + mb_offset;
2024 
2025                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) {
2026                         if (r5l_recovery_verify_data_checksum(
2027                                     log, ctx, page, log_offset,
2028                                     payload->checksum[0]) < 0)
2029                                 goto mismatch;
2030                 } else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_PARITY) {
2031                         if (r5l_recovery_verify_data_checksum(
2032                                     log, ctx, page, log_offset,
2033                                     payload->checksum[0]) < 0)
2034                                 goto mismatch;
2035                         if (conf->max_degraded == 2 && /* q for RAID 6 */
2036                             r5l_recovery_verify_data_checksum(
2037                                     log, ctx, page,
2038                                     r5l_ring_add(log, log_offset,
2039                                                  BLOCK_SECTORS),
2040                                     payload->checksum[1]) < 0)
2041                                 goto mismatch;
2042                 } else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
2043                         /* nothing to do for R5LOG_PAYLOAD_FLUSH here */
2044                 } else /* not R5LOG_PAYLOAD_DATA/PARITY/FLUSH */
2045                         goto mismatch;
2046 
2047                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
2048                         mb_offset += sizeof(struct r5l_payload_flush) +
2049                                 le32_to_cpu(payload_flush->size);
2050                 } else {
2051                         /* DATA or PARITY payload */
2052                         log_offset = r5l_ring_add(log, log_offset,
2053                                                   le32_to_cpu(payload->size));
2054                         mb_offset += sizeof(struct r5l_payload_data_parity) +
2055                                 sizeof(__le32) *
2056                                 (le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
2057                 }
2058 
2059         }
2060 
2061         put_page(page);
2062         return 0;
2063 
2064 mismatch:
2065         put_page(page);
2066         return -EINVAL;
2067 }
2068 
2069 /*
2070  * Analyze all data/parity pages in one meta block
2071  * Returns:
2072  * 0 for success
2073  * -EINVAL for unknown playload type
2074  * -EAGAIN for checksum mismatch of data page
2075  * -ENOMEM for run out of memory (alloc_page failed or run out of stripes)
2076  */
2077 static int
2078 r5c_recovery_analyze_meta_block(struct r5l_log *log,
2079                                 struct r5l_recovery_ctx *ctx,
2080                                 struct list_head *cached_stripe_list)
2081 {
2082         struct mddev *mddev = log->rdev->mddev;
2083         struct r5conf *conf = mddev->private;
2084         struct r5l_meta_block *mb;
2085         struct r5l_payload_data_parity *payload;
2086         struct r5l_payload_flush *payload_flush;
2087         int mb_offset;
2088         sector_t log_offset;
2089         sector_t stripe_sect;
2090         struct stripe_head *sh;
2091         int ret;
2092 
2093         /*
2094          * for mismatch in data blocks, we will drop all data in this mb, but
2095          * we will still read next mb for other data with FLUSH flag, as
2096          * io_unit could finish out of order.
2097          */
2098         ret = r5l_recovery_verify_data_checksum_for_mb(log, ctx);
2099         if (ret == -EINVAL)
2100                 return -EAGAIN;
2101         else if (ret)
2102                 return ret;   /* -ENOMEM duo to alloc_page() failed */
2103 
2104         mb = page_address(ctx->meta_page);
2105         mb_offset = sizeof(struct r5l_meta_block);
2106         log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
2107 
2108         while (mb_offset < le32_to_cpu(mb->meta_size)) {
2109                 int dd;
2110 
2111                 payload = (void *)mb + mb_offset;
2112                 payload_flush = (void *)mb + mb_offset;
2113 
2114                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
2115                         int i, count;
2116 
2117                         count = le32_to_cpu(payload_flush->size) / sizeof(__le64);
2118                         for (i = 0; i < count; ++i) {
2119                                 stripe_sect = le64_to_cpu(payload_flush->flush_stripes[i]);
2120                                 sh = r5c_recovery_lookup_stripe(cached_stripe_list,
2121                                                                 stripe_sect);
2122                                 if (sh) {
2123                                         WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
2124                                         r5l_recovery_reset_stripe(sh);
2125                                         list_del_init(&sh->lru);
2126                                         raid5_release_stripe(sh);
2127                                 }
2128                         }
2129 
2130                         mb_offset += sizeof(struct r5l_payload_flush) +
2131                                 le32_to_cpu(payload_flush->size);
2132                         continue;
2133                 }
2134 
2135                 /* DATA or PARITY payload */
2136                 stripe_sect = (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) ?
2137                         raid5_compute_sector(
2138                                 conf, le64_to_cpu(payload->location), 0, &dd,
2139                                 NULL)
2140                         : le64_to_cpu(payload->location);
2141 
2142                 sh = r5c_recovery_lookup_stripe(cached_stripe_list,
2143                                                 stripe_sect);
2144 
2145                 if (!sh) {
2146                         sh = r5c_recovery_alloc_stripe(conf, stripe_sect, 1);
2147                         /*
2148                          * cannot get stripe from raid5_get_active_stripe
2149                          * try replay some stripes
2150                          */
2151                         if (!sh) {
2152                                 r5c_recovery_replay_stripes(
2153                                         cached_stripe_list, ctx);
2154                                 sh = r5c_recovery_alloc_stripe(
2155                                         conf, stripe_sect, 1);
2156                         }
2157                         if (!sh) {
2158                                 int new_size = conf->min_nr_stripes * 2;
2159                                 pr_debug("md/raid:%s: Increasing stripe cache size to %d to recovery data on journal.\n",
2160                                         mdname(mddev),
2161                                         new_size);
2162                                 ret = raid5_set_cache_size(mddev, new_size);
2163                                 if (conf->min_nr_stripes <= new_size / 2) {
2164                                         pr_err("md/raid:%s: Cannot increase cache size, ret=%d, new_size=%d, min_nr_stripes=%d, max_nr_stripes=%d\n",
2165                                                 mdname(mddev),
2166                                                 ret,
2167                                                 new_size,
2168                                                 conf->min_nr_stripes,
2169                                                 conf->max_nr_stripes);
2170                                         return -ENOMEM;
2171                                 }
2172                                 sh = r5c_recovery_alloc_stripe(
2173                                         conf, stripe_sect, 0);
2174                         }
2175                         if (!sh) {
2176                                 pr_err("md/raid:%s: Cannot get enough stripes due to memory pressure. Recovery failed.\n",
2177                                         mdname(mddev));
2178                                 return -ENOMEM;
2179                         }
2180                         list_add_tail(&sh->lru, cached_stripe_list);
2181                 }
2182 
2183                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) {
2184                         if (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
2185                             test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags)) {
2186                                 r5l_recovery_replay_one_stripe(conf, sh, ctx);
2187                                 list_move_tail(&sh->lru, cached_stripe_list);
2188                         }
2189                         r5l_recovery_load_data(log, sh, ctx, payload,
2190                                                log_offset);
2191                 } else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_PARITY)
2192                         r5l_recovery_load_parity(log, sh, ctx, payload,
2193                                                  log_offset);
2194                 else
2195                         return -EINVAL;
2196 
2197                 log_offset = r5l_ring_add(log, log_offset,
2198                                           le32_to_cpu(payload->size));
2199 
2200                 mb_offset += sizeof(struct r5l_payload_data_parity) +
2201                         sizeof(__le32) *
2202                         (le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
2203         }
2204 
2205         return 0;
2206 }
2207 
2208 /*
2209  * Load the stripe into cache. The stripe will be written out later by
2210  * the stripe cache state machine.
2211  */
2212 static void r5c_recovery_load_one_stripe(struct r5l_log *log,
2213                                          struct stripe_head *sh)
2214 {
2215         struct r5dev *dev;
2216         int i;
2217 
2218         for (i = sh->disks; i--; ) {
2219                 dev = sh->dev + i;
2220                 if (test_and_clear_bit(R5_Wantwrite, &dev->flags)) {
2221                         set_bit(R5_InJournal, &dev->flags);
2222                         set_bit(R5_UPTODATE, &dev->flags);
2223                 }
2224         }
2225 }
2226 
2227 /*
2228  * Scan through the log for all to-be-flushed data
2229  *
2230  * For stripes with data and parity, namely Data-Parity stripe
2231  * (STRIPE_R5C_CACHING == 0), we simply replay all the writes.
2232  *
2233  * For stripes with only data, namely Data-Only stripe
2234  * (STRIPE_R5C_CACHING == 1), we load them to stripe cache state machine.
2235  *
2236  * For a stripe, if we see data after parity, we should discard all previous
2237  * data and parity for this stripe, as these data are already flushed to
2238  * the array.
2239  *
2240  * At the end of the scan, we return the new journal_tail, which points to
2241  * first data-only stripe on the journal device, or next invalid meta block.
2242  */
2243 static int r5c_recovery_flush_log(struct r5l_log *log,
2244                                   struct r5l_recovery_ctx *ctx)
2245 {
2246         struct stripe_head *sh;
2247         int ret = 0;
2248 
2249         /* scan through the log */
2250         while (1) {
2251                 if (r5l_recovery_read_meta_block(log, ctx))
2252                         break;
2253 
2254                 ret = r5c_recovery_analyze_meta_block(log, ctx,
2255                                                       &ctx->cached_list);
2256                 /*
2257                  * -EAGAIN means mismatch in data block, in this case, we still
2258                  * try scan the next metablock
2259                  */
2260                 if (ret && ret != -EAGAIN)
2261                         break;   /* ret == -EINVAL or -ENOMEM */
2262                 ctx->seq++;
2263                 ctx->pos = r5l_ring_add(log, ctx->pos, ctx->meta_total_blocks);
2264         }
2265 
2266         if (ret == -ENOMEM) {
2267                 r5c_recovery_drop_stripes(&ctx->cached_list, ctx);
2268                 return ret;
2269         }
2270 
2271         /* replay data-parity stripes */
2272         r5c_recovery_replay_stripes(&ctx->cached_list, ctx);
2273 
2274         /* load data-only stripes to stripe cache */
2275         list_for_each_entry(sh, &ctx->cached_list, lru) {
2276                 WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
2277                 r5c_recovery_load_one_stripe(log, sh);
2278                 ctx->data_only_stripes++;
2279         }
2280 
2281         return 0;
2282 }
2283 
2284 /*
2285  * we did a recovery. Now ctx.pos points to an invalid meta block. New
2286  * log will start here. but we can't let superblock point to last valid
2287  * meta block. The log might looks like:
2288  * | meta 1| meta 2| meta 3|
2289  * meta 1 is valid, meta 2 is invalid. meta 3 could be valid. If
2290  * superblock points to meta 1, we write a new valid meta 2n.  if crash
2291  * happens again, new recovery will start from meta 1. Since meta 2n is
2292  * valid now, recovery will think meta 3 is valid, which is wrong.
2293  * The solution is we create a new meta in meta2 with its seq == meta
2294  * 1's seq + 10000 and let superblock points to meta2. The same recovery
2295  * will not think meta 3 is a valid meta, because its seq doesn't match
2296  */
2297 
2298 /*
2299  * Before recovery, the log looks like the following
2300  *
2301  *   ---------------------------------------------
2302  *   |           valid log        | invalid log  |
2303  *   ---------------------------------------------
2304  *   ^
2305  *   |- log->last_checkpoint
2306  *   |- log->last_cp_seq
2307  *
2308  * Now we scan through the log until we see invalid entry
2309  *
2310  *   ---------------------------------------------
2311  *   |           valid log        | invalid log  |
2312  *   ---------------------------------------------
2313  *   ^                            ^
2314  *   |- log->last_checkpoint      |- ctx->pos
2315  *   |- log->last_cp_seq          |- ctx->seq
2316  *
2317  * From this point, we need to increase seq number by 10 to avoid
2318  * confusing next recovery.
2319  *
2320  *   ---------------------------------------------
2321  *   |           valid log        | invalid log  |
2322  *   ---------------------------------------------
2323  *   ^                              ^
2324  *   |- log->last_checkpoint        |- ctx->pos+1
2325  *   |- log->last_cp_seq            |- ctx->seq+10001
2326  *
2327  * However, it is not safe to start the state machine yet, because data only
2328  * parities are not yet secured in RAID. To save these data only parities, we
2329  * rewrite them from seq+11.
2330  *
2331  *   -----------------------------------------------------------------
2332  *   |           valid log        | data only stripes | invalid log  |
2333  *   -----------------------------------------------------------------
2334  *   ^                                                ^
2335  *   |- log->last_checkpoint                          |- ctx->pos+n
2336  *   |- log->last_cp_seq                              |- ctx->seq+10000+n
2337  *
2338  * If failure happens again during this process, the recovery can safe start
2339  * again from log->last_checkpoint.
2340  *
2341  * Once data only stripes are rewritten to journal, we move log_tail
2342  *
2343  *   -----------------------------------------------------------------
2344  *   |     old log        |    data only stripes    | invalid log  |
2345  *   -----------------------------------------------------------------
2346  *                        ^                         ^
2347  *                        |- log->last_checkpoint   |- ctx->pos+n
2348  *                        |- log->last_cp_seq       |- ctx->seq+10000+n
2349  *
2350  * Then we can safely start the state machine. If failure happens from this
2351  * point on, the recovery will start from new log->last_checkpoint.
2352  */
2353 static int
2354 r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
2355                                        struct r5l_recovery_ctx *ctx)
2356 {
2357         struct stripe_head *sh;
2358         struct mddev *mddev = log->rdev->mddev;
2359         struct page *page;
2360         sector_t next_checkpoint = MaxSector;
2361 
2362         page = alloc_page(GFP_KERNEL);
2363         if (!page) {
2364                 pr_err("md/raid:%s: cannot allocate memory to rewrite data only stripes\n",
2365                        mdname(mddev));
2366                 return -ENOMEM;
2367         }
2368 
2369         WARN_ON(list_empty(&ctx->cached_list));
2370 
2371         list_for_each_entry(sh, &ctx->cached_list, lru) {
2372                 struct r5l_meta_block *mb;
2373                 int i;
2374                 int offset;
2375                 sector_t write_pos;
2376 
2377                 WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
2378                 r5l_recovery_create_empty_meta_block(log, page,
2379                                                      ctx->pos, ctx->seq);
2380                 mb = page_address(page);
2381                 offset = le32_to_cpu(mb->meta_size);
2382                 write_pos = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
2383 
2384                 for (i = sh->disks; i--; ) {
2385                         struct r5dev *dev = &sh->dev[i];
2386                         struct r5l_payload_data_parity *payload;
2387                         void *addr;
2388 
2389                         if (test_bit(R5_InJournal, &dev->flags)) {
2390                                 payload = (void *)mb + offset;
2391                                 payload->header.type = cpu_to_le16(
2392                                         R5LOG_PAYLOAD_DATA);
2393                                 payload->size = cpu_to_le32(BLOCK_SECTORS);
2394                                 payload->location = cpu_to_le64(
2395                                         raid5_compute_blocknr(sh, i, 0));
2396                                 addr = kmap_atomic(dev->page);
2397                                 payload->checksum[0] = cpu_to_le32(
2398                                         crc32c_le(log->uuid_checksum, addr,
2399                                                   PAGE_SIZE));
2400                                 kunmap_atomic(addr);
2401                                 sync_page_io(log->rdev, write_pos, PAGE_SIZE,
2402                                              dev->page, REQ_OP_WRITE, 0, false);
2403                                 write_pos = r5l_ring_add(log, write_pos,
2404                                                          BLOCK_SECTORS);
2405                                 offset += sizeof(__le32) +
2406                                         sizeof(struct r5l_payload_data_parity);
2407 
2408                         }
2409                 }
2410                 mb->meta_size = cpu_to_le32(offset);
2411                 mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
2412                                                      mb, PAGE_SIZE));
2413                 sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page,
2414                              REQ_OP_WRITE, REQ_SYNC | REQ_FUA, false);
2415                 sh->log_start = ctx->pos;
2416                 list_add_tail(&sh->r5c, &log->stripe_in_journal_list);
2417                 atomic_inc(&log->stripe_in_journal_count);
2418                 ctx->pos = write_pos;
2419                 ctx->seq += 1;
2420                 next_checkpoint = sh->log_start;
2421         }
2422         log->next_checkpoint = next_checkpoint;
2423         __free_page(page);
2424         return 0;
2425 }
2426 
2427 static void r5c_recovery_flush_data_only_stripes(struct r5l_log *log,
2428                                                  struct r5l_recovery_ctx *ctx)
2429 {
2430         struct mddev *mddev = log->rdev->mddev;
2431         struct r5conf *conf = mddev->private;
2432         struct stripe_head *sh, *next;
2433 
2434         if (ctx->data_only_stripes == 0)
2435                 return;
2436 
2437         log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_BACK;
2438 
2439         list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {
2440                 r5c_make_stripe_write_out(sh);
2441                 set_bit(STRIPE_HANDLE, &sh->state);
2442                 list_del_init(&sh->lru);
2443                 raid5_release_stripe(sh);
2444         }
2445 
2446         /* reuse conf->wait_for_quiescent in recovery */
2447         wait_event(conf->wait_for_quiescent,
2448                    atomic_read(&conf->active_stripes) == 0);
2449 
2450         log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
2451 }
2452 
2453 static int r5l_recovery_log(struct r5l_log *log)
2454 {
2455         struct mddev *mddev = log->rdev->mddev;
2456         struct r5l_recovery_ctx *ctx;
2457         int ret;
2458         sector_t pos;
2459 
2460         ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
2461         if (!ctx)
2462                 return -ENOMEM;
2463 
2464         ctx->pos = log->last_checkpoint;
2465         ctx->seq = log->last_cp_seq;
2466         INIT_LIST_HEAD(&ctx->cached_list);
2467         ctx->meta_page = alloc_page(GFP_KERNEL);
2468 
2469         if (!ctx->meta_page) {
2470                 ret =  -ENOMEM;
2471                 goto meta_page;
2472         }
2473 
2474         if (r5l_recovery_allocate_ra_pool(log, ctx) != 0) {
2475                 ret = -ENOMEM;
2476                 goto ra_pool;
2477         }
2478 
2479         ret = r5c_recovery_flush_log(log, ctx);
2480 
2481         if (ret)
2482                 goto error;
2483 
2484         pos = ctx->pos;
2485         ctx->seq += 10000;
2486 
2487         if ((ctx->data_only_stripes == 0) && (ctx->data_parity_stripes == 0))
2488                 pr_info("md/raid:%s: starting from clean shutdown\n",
2489                          mdname(mddev));
2490         else
2491                 pr_info("md/raid:%s: recovering %d data-only stripes and %d data-parity stripes\n",
2492                          mdname(mddev), ctx->data_only_stripes,
2493                          ctx->data_parity_stripes);
2494 
2495         if (ctx->data_only_stripes == 0) {
2496                 log->next_checkpoint = ctx->pos;
2497                 r5l_log_write_empty_meta_block(log, ctx->pos, ctx->seq++);
2498                 ctx->pos = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
2499         } else if (r5c_recovery_rewrite_data_only_stripes(log, ctx)) {
2500                 pr_err("md/raid:%s: failed to rewrite stripes to journal\n",
2501                        mdname(mddev));
2502                 ret =  -EIO;
2503                 goto error;
2504         }
2505 
2506         log->log_start = ctx->pos;
2507         log->seq = ctx->seq;
2508         log->last_checkpoint = pos;
2509         r5l_write_super(log, pos);
2510 
2511         r5c_recovery_flush_data_only_stripes(log, ctx);
2512         ret = 0;
2513 error:
2514         r5l_recovery_free_ra_pool(log, ctx);
2515 ra_pool:
2516         __free_page(ctx->meta_page);
2517 meta_page:
2518         kfree(ctx);
2519         return ret;
2520 }
2521 
2522 static void r5l_write_super(struct r5l_log *log, sector_t cp)
2523 {
2524         struct mddev *mddev = log->rdev->mddev;
2525 
2526         log->rdev->journal_tail = cp;
2527         set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
2528 }
2529 
2530 static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
2531 {
2532         struct r5conf *conf;
2533         int ret;
2534 
2535         ret = mddev_lock(mddev);
2536         if (ret)
2537                 return ret;
2538 
2539         conf = mddev->private;
2540         if (!conf || !conf->log) {
2541                 mddev_unlock(mddev);
2542                 return 0;
2543         }
2544 
2545         switch (conf->log->r5c_journal_mode) {
2546         case R5C_JOURNAL_MODE_WRITE_THROUGH:
2547                 ret = snprintf(
2548                         page, PAGE_SIZE, "[%s] %s\n",
2549                         r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_THROUGH],
2550                         r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_BACK]);
2551                 break;
2552         case R5C_JOURNAL_MODE_WRITE_BACK:
2553                 ret = snprintf(
2554                         page, PAGE_SIZE, "%s [%s]\n",
2555                         r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_THROUGH],
2556                         r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_BACK]);
2557                 break;
2558         default:
2559                 ret = 0;
2560         }
2561         mddev_unlock(mddev);
2562         return ret;
2563 }
2564 
2565 /*
2566  * Set journal cache mode on @mddev (external API initially needed by dm-raid).
2567  *
2568  * @mode as defined in 'enum r5c_journal_mode'.
2569  *
2570  */
2571 int r5c_journal_mode_set(struct mddev *mddev, int mode)
2572 {
2573         struct r5conf *conf;
2574 
2575         if (mode < R5C_JOURNAL_MODE_WRITE_THROUGH ||
2576             mode > R5C_JOURNAL_MODE_WRITE_BACK)
2577                 return -EINVAL;
2578 
2579         conf = mddev->private;
2580         if (!conf || !conf->log)
2581                 return -ENODEV;
2582 
2583         if (raid5_calc_degraded(conf) > 0 &&
2584             mode == R5C_JOURNAL_MODE_WRITE_BACK)
2585                 return -EINVAL;
2586 
2587         mddev_suspend(mddev);
2588         conf->log->r5c_journal_mode = mode;
2589         mddev_resume(mddev);
2590 
2591         pr_debug("md/raid:%s: setting r5c cache mode to %d: %s\n",
2592                  mdname(mddev), mode, r5c_journal_mode_str[mode]);
2593         return 0;
2594 }
2595 EXPORT_SYMBOL(r5c_journal_mode_set);
2596 
2597 static ssize_t r5c_journal_mode_store(struct mddev *mddev,
2598                                       const char *page, size_t length)
2599 {
2600         int mode = ARRAY_SIZE(r5c_journal_mode_str);
2601         size_t len = length;
2602         int ret;
2603 
2604         if (len < 2)
2605                 return -EINVAL;
2606 
2607         if (page[len - 1] == '\n')
2608                 len--;
2609 
2610         while (mode--)
2611                 if (strlen(r5c_journal_mode_str[mode]) == len &&
2612                     !strncmp(page, r5c_journal_mode_str[mode], len))
2613                         break;
2614         ret = mddev_lock(mddev);
2615         if (ret)
2616                 return ret;
2617         ret = r5c_journal_mode_set(mddev, mode);
2618         mddev_unlock(mddev);
2619         return ret ?: length;
2620 }
2621 
2622 struct md_sysfs_entry
2623 r5c_journal_mode = __ATTR(journal_mode, 0644,
2624                           r5c_journal_mode_show, r5c_journal_mode_store);
2625 
2626 /*
2627  * Try handle write operation in caching phase. This function should only
2628  * be called in write-back mode.
2629  *
2630  * If all outstanding writes can be handled in caching phase, returns 0
2631  * If writes requires write-out phase, call r5c_make_stripe_write_out()
2632  * and returns -EAGAIN
2633  */
2634 int r5c_try_caching_write(struct r5conf *conf,
2635                           struct stripe_head *sh,
2636                           struct stripe_head_state *s,
2637                           int disks)
2638 {
2639         struct r5l_log *log = conf->log;
2640         int i;
2641         struct r5dev *dev;
2642         int to_cache = 0;
2643         void **pslot;
2644         sector_t tree_index;
2645         int ret;
2646         uintptr_t refcount;
2647 
2648         BUG_ON(!r5c_is_writeback(log));
2649 
2650         if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
2651                 /*
2652                  * There are two different scenarios here:
2653                  *  1. The stripe has some data cached, and it is sent to
2654                  *     write-out phase for reclaim
2655                  *  2. The stripe is clean, and this is the first write
2656                  *
2657                  * For 1, return -EAGAIN, so we continue with
2658                  * handle_stripe_dirtying().
2659                  *
2660                  * For 2, set STRIPE_R5C_CACHING and continue with caching
2661                  * write.
2662                  */
2663 
2664                 /* case 1: anything injournal or anything in written */
2665                 if (s->injournal > 0 || s->written > 0)
2666                         return -EAGAIN;
2667                 /* case 2 */
2668                 set_bit(STRIPE_R5C_CACHING, &sh->state);
2669         }
2670 
2671         /*
2672          * When run in degraded mode, array is set to write-through mode.
2673          * This check helps drain pending write safely in the transition to
2674          * write-through mode.
2675          *
2676          * When a stripe is syncing, the write is also handled in write
2677          * through mode.
2678          */
2679         if (s->failed || test_bit(STRIPE_SYNCING, &sh->state)) {
2680                 r5c_make_stripe_write_out(sh);
2681                 return -EAGAIN;
2682         }
2683 
2684         for (i = disks; i--; ) {
2685                 dev = &sh->dev[i];
2686                 /* if non-overwrite, use writing-out phase */
2687                 if (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags) &&
2688                     !test_bit(R5_InJournal, &dev->flags)) {
2689                         r5c_make_stripe_write_out(sh);
2690                         return -EAGAIN;
2691                 }
2692         }
2693 
2694         /* if the stripe is not counted in big_stripe_tree, add it now */
2695         if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) &&
2696             !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
2697                 tree_index = r5c_tree_index(conf, sh->sector);
2698                 spin_lock(&log->tree_lock);
2699                 pslot = radix_tree_lookup_slot(&log->big_stripe_tree,
2700                                                tree_index);
2701                 if (pslot) {
2702                         refcount = (uintptr_t)radix_tree_deref_slot_protected(
2703                                 pslot, &log->tree_lock) >>
2704                                 R5C_RADIX_COUNT_SHIFT;
2705                         radix_tree_replace_slot(
2706                                 &log->big_stripe_tree, pslot,
2707                                 (void *)((refcount + 1) << R5C_RADIX_COUNT_SHIFT));
2708                 } else {
2709                         /*
2710                          * this radix_tree_insert can fail safely, so no
2711                          * need to call radix_tree_preload()
2712                          */
2713                         ret = radix_tree_insert(
2714                                 &log->big_stripe_tree, tree_index,
2715                                 (void *)(1 << R5C_RADIX_COUNT_SHIFT));
2716                         if (ret) {
2717                                 spin_unlock(&log->tree_lock);
2718                                 r5c_make_stripe_write_out(sh);
2719                                 return -EAGAIN;
2720                         }
2721                 }
2722                 spin_unlock(&log->tree_lock);
2723 
2724                 /*
2725                  * set STRIPE_R5C_PARTIAL_STRIPE, this shows the stripe is
2726                  * counted in the radix tree
2727                  */
2728                 set_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state);
2729                 atomic_inc(&conf->r5c_cached_partial_stripes);
2730         }
2731 
2732         for (i = disks; i--; ) {
2733                 dev = &sh->dev[i];
2734                 if (dev->towrite) {
2735                         set_bit(R5_Wantwrite, &dev->flags);
2736                         set_bit(R5_Wantdrain, &dev->flags);
2737                         set_bit(R5_LOCKED, &dev->flags);
2738                         to_cache++;
2739                 }
2740         }
2741 
2742         if (to_cache) {
2743                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2744                 /*
2745                  * set STRIPE_LOG_TRAPPED, which triggers r5c_cache_data()
2746                  * in ops_run_io(). STRIPE_LOG_TRAPPED will be cleared in
2747                  * r5c_handle_data_cached()
2748                  */
2749                 set_bit(STRIPE_LOG_TRAPPED, &sh->state);
2750         }
2751 
2752         return 0;
2753 }
2754 
2755 /*
2756  * free extra pages (orig_page) we allocated for prexor
2757  */
2758 void r5c_release_extra_page(struct stripe_head *sh)
2759 {
2760         struct r5conf *conf = sh->raid_conf;
2761         int i;
2762         bool using_disk_info_extra_page;
2763 
2764         using_disk_info_extra_page =
2765                 sh->dev[0].orig_page == conf->disks[0].extra_page;
2766 
2767         for (i = sh->disks; i--; )
2768                 if (sh->dev[i].page != sh->dev[i].orig_page) {
2769                         struct page *p = sh->dev[i].orig_page;
2770 
2771                         sh->dev[i].orig_page = sh->dev[i].page;
2772                         clear_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2773 
2774                         if (!using_disk_info_extra_page)
2775                                 put_page(p);
2776                 }
2777 
2778         if (using_disk_info_extra_page) {
2779                 clear_bit(R5C_EXTRA_PAGE_IN_USE, &conf->cache_state);
2780                 md_wakeup_thread(conf->mddev->thread);
2781         }
2782 }
2783 
2784 void r5c_use_extra_page(struct stripe_head *sh)
2785 {
2786         struct r5conf *conf = sh->raid_conf;
2787         int i;
2788         struct r5dev *dev;
2789 
2790         for (i = sh->disks; i--; ) {
2791                 dev = &sh->dev[i];
2792                 if (dev->orig_page != dev->page)
2793                         put_page(dev->orig_page);
2794                 dev->orig_page = conf->disks[i].extra_page;
2795         }
2796 }
2797 
2798 /*
2799  * clean up the stripe (clear R5_InJournal for dev[pd_idx] etc.) after the
2800  * stripe is committed to RAID disks.
2801  */
2802 void r5c_finish_stripe_write_out(struct r5conf *conf,
2803                                  struct stripe_head *sh,
2804                                  struct stripe_head_state *s)
2805 {
2806         struct r5l_log *log = conf->log;
2807         int i;
2808         int do_wakeup = 0;
2809         sector_t tree_index;
2810         void **pslot;
2811         uintptr_t refcount;
2812 
2813         if (!log || !test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags))
2814                 return;
2815 
2816         WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
2817         clear_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
2818 
2819         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
2820                 return;
2821 
2822         for (i = sh->disks; i--; ) {
2823                 clear_bit(R5_InJournal, &sh->dev[i].flags);
2824                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2825                         do_wakeup = 1;
2826         }
2827 
2828         /*
2829          * analyse_stripe() runs before r5c_finish_stripe_write_out(),
2830          * We updated R5_InJournal, so we also update s->injournal.
2831          */
2832         s->injournal = 0;
2833 
2834         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2835                 if (atomic_dec_and_test(&conf->pending_full_writes))
2836                         md_wakeup_thread(conf->mddev->thread);
2837 
2838         if (do_wakeup)
2839                 wake_up(&conf->wait_for_overlap);
2840 
2841         spin_lock_irq(&log->stripe_in_journal_lock);
2842         list_del_init(&sh->r5c);
2843         spin_unlock_irq(&log->stripe_in_journal_lock);
2844         sh->log_start = MaxSector;
2845 
2846         atomic_dec(&log->stripe_in_journal_count);
2847         r5c_update_log_state(log);
2848 
2849         /* stop counting this stripe in big_stripe_tree */
2850         if (test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) ||
2851             test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
2852                 tree_index = r5c_tree_index(conf, sh->sector);
2853                 spin_lock(&log->tree_lock);
2854                 pslot = radix_tree_lookup_slot(&log->big_stripe_tree,
2855                                                tree_index);
2856                 BUG_ON(pslot == NULL);
2857                 refcount = (uintptr_t)radix_tree_deref_slot_protected(
2858                         pslot, &log->tree_lock) >>
2859                         R5C_RADIX_COUNT_SHIFT;
2860                 if (refcount == 1)
2861                         radix_tree_delete(&log->big_stripe_tree, tree_index);
2862                 else
2863                         radix_tree_replace_slot(
2864                                 &log->big_stripe_tree, pslot,
2865                                 (void *)((refcount - 1) << R5C_RADIX_COUNT_SHIFT));
2866                 spin_unlock(&log->tree_lock);
2867         }
2868 
2869         if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) {
2870                 BUG_ON(atomic_read(&conf->r5c_cached_partial_stripes) == 0);
2871                 atomic_dec(&conf->r5c_flushing_partial_stripes);
2872                 atomic_dec(&conf->r5c_cached_partial_stripes);
2873         }
2874 
2875         if (test_and_clear_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
2876                 BUG_ON(atomic_read(&conf->r5c_cached_full_stripes) == 0);
2877                 atomic_dec(&conf->r5c_flushing_full_stripes);
2878                 atomic_dec(&conf->r5c_cached_full_stripes);
2879         }
2880 
2881         r5l_append_flush_payload(log, sh->sector);
2882         /* stripe is flused to raid disks, we can do resync now */
2883         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2884                 set_bit(STRIPE_HANDLE, &sh->state);
2885 }
2886 
2887 int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh)
2888 {
2889         struct r5conf *conf = sh->raid_conf;
2890         int pages = 0;
2891         int reserve;
2892         int i;
2893         int ret = 0;
2894 
2895         BUG_ON(!log);
2896 
2897         for (i = 0; i < sh->disks; i++) {
2898                 void *addr;
2899 
2900                 if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
2901                         continue;
2902                 addr = kmap_atomic(sh->dev[i].page);
2903                 sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
2904                                                     addr, PAGE_SIZE);
2905                 kunmap_atomic(addr);
2906                 pages++;
2907         }
2908         WARN_ON(pages == 0);
2909 
2910         /*
2911          * The stripe must enter state machine again to call endio, so
2912          * don't delay.
2913          */
2914         clear_bit(STRIPE_DELAYED, &sh->state);
2915         atomic_inc(&sh->count);
2916 
2917         mutex_lock(&log->io_mutex);
2918         /* meta + data */
2919         reserve = (1 + pages) << (PAGE_SHIFT - 9);
2920 
2921         if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
2922             sh->log_start == MaxSector)
2923                 r5l_add_no_space_stripe(log, sh);
2924         else if (!r5l_has_free_space(log, reserve)) {
2925                 if (sh->log_start == log->last_checkpoint)
2926                         BUG();
2927                 else
2928                         r5l_add_no_space_stripe(log, sh);
2929         } else {
2930                 ret = r5l_log_stripe(log, sh, pages, 0);
2931                 if (ret) {
2932                         spin_lock_irq(&log->io_list_lock);
2933                         list_add_tail(&sh->log_list, &log->no_mem_stripes);
2934                         spin_unlock_irq(&log->io_list_lock);
2935                 }
2936         }
2937 
2938         mutex_unlock(&log->io_mutex);
2939         return 0;
2940 }
2941 
2942 /* check whether this big stripe is in write back cache. */
2943 bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect)
2944 {
2945         struct r5l_log *log = conf->log;
2946         sector_t tree_index;
2947         void *slot;
2948 
2949         if (!log)
2950                 return false;
2951 
2952         WARN_ON_ONCE(!rcu_read_lock_held());
2953         tree_index = r5c_tree_index(conf, sect);
2954         slot = radix_tree_lookup(&log->big_stripe_tree, tree_index);
2955         return slot != NULL;
2956 }
2957 
2958 static int r5l_load_log(struct r5l_log *log)
2959 {
2960         struct md_rdev *rdev = log->rdev;
2961         struct page *page;
2962         struct r5l_meta_block *mb;
2963         sector_t cp = log->rdev->journal_tail;
2964         u32 stored_crc, expected_crc;
2965         bool create_super = false;
2966         int ret = 0;
2967 
2968         /* Make sure it's valid */
2969         if (cp >= rdev->sectors || round_down(cp, BLOCK_SECTORS) != cp)
2970                 cp = 0;
2971         page = alloc_page(GFP_KERNEL);
2972         if (!page)
2973                 return -ENOMEM;
2974 
2975         if (!sync_page_io(rdev, cp, PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
2976                 ret = -EIO;
2977                 goto ioerr;
2978         }
2979         mb = page_address(page);
2980 
2981         if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
2982             mb->version != R5LOG_VERSION) {
2983                 create_super = true;
2984                 goto create;
2985         }
2986         stored_crc = le32_to_cpu(mb->checksum);
2987         mb->checksum = 0;
2988         expected_crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
2989         if (stored_crc != expected_crc) {
2990                 create_super = true;
2991                 goto create;
2992         }
2993         if (le64_to_cpu(mb->position) != cp) {
2994                 create_super = true;
2995                 goto create;
2996         }
2997 create:
2998         if (create_super) {
2999                 log->last_cp_seq = prandom_u32();
3000                 cp = 0;
3001                 r5l_log_write_empty_meta_block(log, cp, log->last_cp_seq);
3002                 /*
3003                  * Make sure super points to correct address. Log might have
3004                  * data very soon. If super hasn't correct log tail address,
3005                  * recovery can't find the log
3006                  */
3007                 r5l_write_super(log, cp);
3008         } else
3009                 log->last_cp_seq = le64_to_cpu(mb->seq);
3010 
3011         log->device_size = round_down(rdev->sectors, BLOCK_SECTORS);
3012         log->max_free_space = log->device_size >> RECLAIM_MAX_FREE_SPACE_SHIFT;
3013         if (log->max_free_space > RECLAIM_MAX_FREE_SPACE)
3014                 log->max_free_space = RECLAIM_MAX_FREE_SPACE;
3015         log->last_checkpoint = cp;
3016 
3017         __free_page(page);
3018 
3019         if (create_super) {
3020                 log->log_start = r5l_ring_add(log, cp, BLOCK_SECTORS);
3021                 log->seq = log->last_cp_seq + 1;
3022                 log->next_checkpoint = cp;
3023         } else
3024                 ret = r5l_recovery_log(log);
3025 
3026         r5c_update_log_state(log);
3027         return ret;
3028 ioerr:
3029         __free_page(page);
3030         return ret;
3031 }
3032 
3033 int r5l_start(struct r5l_log *log)
3034 {
3035         int ret;
3036 
3037         if (!log)
3038                 return 0;
3039 
3040         ret = r5l_load_log(log);
3041         if (ret) {
3042                 struct mddev *mddev = log->rdev->mddev;
3043                 struct r5conf *conf = mddev->private;
3044 
3045                 r5l_exit_log(conf);
3046         }
3047         return ret;
3048 }
3049 
3050 void r5c_update_on_rdev_error(struct mddev *mddev, struct md_rdev *rdev)
3051 {
3052         struct r5conf *conf = mddev->private;
3053         struct r5l_log *log = conf->log;
3054 
3055         if (!log)
3056                 return;
3057 
3058         if ((raid5_calc_degraded(conf) > 0 ||
3059              test_bit(Journal, &rdev->flags)) &&
3060             conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK)
3061                 schedule_work(&log->disable_writeback_work);
3062 }
3063 
3064 int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
3065 {
3066         struct request_queue *q = bdev_get_queue(rdev->bdev);
3067         struct r5l_log *log;
3068         char b[BDEVNAME_SIZE];
3069         int ret;
3070 
3071         pr_debug("md/raid:%s: using device %s as journal\n",
3072                  mdname(conf->mddev), bdevname(rdev->bdev, b));
3073 
3074         if (PAGE_SIZE != 4096)
3075                 return -EINVAL;
3076 
3077         /*
3078          * The PAGE_SIZE must be big enough to hold 1 r5l_meta_block and
3079          * raid_disks r5l_payload_data_parity.
3080          *
3081          * Write journal and cache does not work for very big array
3082          * (raid_disks > 203)
3083          */
3084         if (sizeof(struct r5l_meta_block) +
3085             ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32)) *
3086              conf->raid_disks) > PAGE_SIZE) {
3087                 pr_err("md/raid:%s: write journal/cache doesn't work for array with %d disks\n",
3088                        mdname(conf->mddev), conf->raid_disks);
3089                 return -EINVAL;
3090         }
3091 
3092         log = kzalloc(sizeof(*log), GFP_KERNEL);
3093         if (!log)
3094                 return -ENOMEM;
3095         log->rdev = rdev;
3096 
3097         log->need_cache_flush = test_bit(QUEUE_FLAG_WC, &q->queue_flags) != 0;
3098 
3099         log->uuid_checksum = crc32c_le(~0, rdev->mddev->uuid,
3100                                        sizeof(rdev->mddev->uuid));
3101 
3102         mutex_init(&log->io_mutex);
3103 
3104         spin_lock_init(&log->io_list_lock);
3105         INIT_LIST_HEAD(&log->running_ios);
3106         INIT_LIST_HEAD(&log->io_end_ios);
3107         INIT_LIST_HEAD(&log->flushing_ios);
3108         INIT_LIST_HEAD(&log->finished_ios);
3109         bio_init(&log->flush_bio, NULL, 0);
3110 
3111         log->io_kc = KMEM_CACHE(r5l_io_unit, 0);
3112         if (!log->io_kc)
3113                 goto io_kc;
3114 
3115         ret = mempool_init_slab_pool(&log->io_pool, R5L_POOL_SIZE, log->io_kc);
3116         if (ret)
3117                 goto io_pool;
3118 
3119         ret = bioset_init(&log->bs, R5L_POOL_SIZE, 0, BIOSET_NEED_BVECS);
3120         if (ret)
3121                 goto io_bs;
3122 
3123         ret = mempool_init_page_pool(&log->meta_pool, R5L_POOL_SIZE, 0);
3124         if (ret)
3125                 goto out_mempool;
3126 
3127         spin_lock_init(&log->tree_lock);
3128         INIT_RADIX_TREE(&log->big_stripe_tree, GFP_NOWAIT | __GFP_NOWARN);
3129 
3130         log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
3131                                                  log->rdev->mddev, "reclaim");
3132         if (!log->reclaim_thread)
3133                 goto reclaim_thread;
3134         log->reclaim_thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;
3135 
3136         init_waitqueue_head(&log->iounit_wait);
3137 
3138         INIT_LIST_HEAD(&log->no_mem_stripes);
3139 
3140         INIT_LIST_HEAD(&log->no_space_stripes);
3141         spin_lock_init(&log->no_space_stripes_lock);
3142 
3143         INIT_WORK(&log->deferred_io_work, r5l_submit_io_async);
3144         INIT_WORK(&log->disable_writeback_work, r5c_disable_writeback_async);
3145 
3146         log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
3147         INIT_LIST_HEAD(&log->stripe_in_journal_list);
3148         spin_lock_init(&log->stripe_in_journal_lock);
3149         atomic_set(&log->stripe_in_journal_count, 0);
3150 
3151         rcu_assign_pointer(conf->log, log);
3152 
3153         set_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
3154         return 0;
3155 
3156 reclaim_thread:
3157         mempool_exit(&log->meta_pool);
3158 out_mempool:
3159         bioset_exit(&log->bs);
3160 io_bs:
3161         mempool_exit(&log->io_pool);
3162 io_pool:
3163         kmem_cache_destroy(log->io_kc);
3164 io_kc:
3165         kfree(log);
3166         return -EINVAL;
3167 }
3168 
3169 void r5l_exit_log(struct r5conf *conf)
3170 {
3171         struct r5l_log *log = conf->log;
3172 
3173         conf->log = NULL;
3174         synchronize_rcu();
3175 
3176         /* Ensure disable_writeback_work wakes up and exits */
3177         wake_up(&conf->mddev->sb_wait);
3178         flush_work(&log->disable_writeback_work);
3179         md_unregister_thread(&log->reclaim_thread);
3180         mempool_exit(&log->meta_pool);
3181         bioset_exit(&log->bs);
3182         mempool_exit(&log->io_pool);
3183         kmem_cache_destroy(log->io_kc);
3184         kfree(log);
3185 }