raid5-ppl: PPL support for disks with write-back cache enabled
[sfrench/cifs-2.6.git] / drivers / md / raid5-cache.c
1 /*
2  * Copyright (C) 2015 Shaohua Li <shli@fb.com>
3  * Copyright (C) 2016 Song Liu <songliubraving@fb.com>
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms and conditions of the GNU General Public License,
7  * version 2, as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12  * more details.
13  *
14  */
15 #include <linux/kernel.h>
16 #include <linux/wait.h>
17 #include <linux/blkdev.h>
18 #include <linux/slab.h>
19 #include <linux/raid/md_p.h>
20 #include <linux/crc32c.h>
21 #include <linux/random.h>
22 #include <linux/kthread.h>
23 #include <linux/types.h>
24 #include "md.h"
25 #include "raid5.h"
26 #include "md-bitmap.h"
27 #include "raid5-log.h"
28
29 /*
30  * metadata/data stored in disk with 4k size unit (a block) regardless
31  * underneath hardware sector size. only works with PAGE_SIZE == 4096
32  */
33 #define BLOCK_SECTORS (8)
34 #define BLOCK_SECTOR_SHIFT (3)
35
36 /*
37  * log->max_free_space is min(1/4 disk size, 10G reclaimable space).
38  *
39  * In write through mode, the reclaim runs every log->max_free_space.
40  * This can prevent the recovery scans for too long
41  */
42 #define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */
43 #define RECLAIM_MAX_FREE_SPACE_SHIFT (2)
44
45 /* wake up reclaim thread periodically */
46 #define R5C_RECLAIM_WAKEUP_INTERVAL (30 * HZ)
47 /* start flush with these full stripes */
48 #define R5C_FULL_STRIPE_FLUSH_BATCH(conf) (conf->max_nr_stripes / 4)
49 /* reclaim stripes in groups */
50 #define R5C_RECLAIM_STRIPE_GROUP (NR_STRIPE_HASH_LOCKS * 2)
51
52 /*
53  * We only need 2 bios per I/O unit to make progress, but ensure we
54  * have a few more available to not get too tight.
55  */
56 #define R5L_POOL_SIZE   4
57
58 static char *r5c_journal_mode_str[] = {"write-through",
59                                        "write-back"};
60 /*
61  * raid5 cache state machine
62  *
63  * With the RAID cache, each stripe works in two phases:
64  *      - caching phase
65  *      - writing-out phase
66  *
67  * These two phases are controlled by bit STRIPE_R5C_CACHING:
68  *   if STRIPE_R5C_CACHING == 0, the stripe is in writing-out phase
69  *   if STRIPE_R5C_CACHING == 1, the stripe is in caching phase
70  *
71  * When there is no journal, or the journal is in write-through mode,
72  * the stripe is always in writing-out phase.
73  *
74  * For write-back journal, the stripe is sent to caching phase on write
75  * (r5c_try_caching_write). r5c_make_stripe_write_out() kicks off
76  * the write-out phase by clearing STRIPE_R5C_CACHING.
77  *
78  * Stripes in caching phase do not write the raid disks. Instead, all
79  * writes are committed from the log device. Therefore, a stripe in
80  * caching phase handles writes as:
81  *      - write to log device
82  *      - return IO
83  *
84  * Stripes in writing-out phase handle writes as:
85  *      - calculate parity
86  *      - write pending data and parity to journal
87  *      - write data and parity to raid disks
88  *      - return IO for pending writes
89  */
90
91 struct r5l_log {
92         struct md_rdev *rdev;
93
94         u32 uuid_checksum;
95
96         sector_t device_size;           /* log device size, round to
97                                          * BLOCK_SECTORS */
98         sector_t max_free_space;        /* reclaim run if free space is at
99                                          * this size */
100
101         sector_t last_checkpoint;       /* log tail. where recovery scan
102                                          * starts from */
103         u64 last_cp_seq;                /* log tail sequence */
104
105         sector_t log_start;             /* log head. where new data appends */
106         u64 seq;                        /* log head sequence */
107
108         sector_t next_checkpoint;
109
110         struct mutex io_mutex;
111         struct r5l_io_unit *current_io; /* current io_unit accepting new data */
112
113         spinlock_t io_list_lock;
114         struct list_head running_ios;   /* io_units which are still running,
115                                          * and have not yet been completely
116                                          * written to the log */
117         struct list_head io_end_ios;    /* io_units which have been completely
118                                          * written to the log but not yet written
119                                          * to the RAID */
120         struct list_head flushing_ios;  /* io_units which are waiting for log
121                                          * cache flush */
122         struct list_head finished_ios;  /* io_units which settle down in log disk */
123         struct bio flush_bio;
124
125         struct list_head no_mem_stripes;   /* pending stripes, -ENOMEM */
126
127         struct kmem_cache *io_kc;
128         mempool_t *io_pool;
129         struct bio_set *bs;
130         mempool_t *meta_pool;
131
132         struct md_thread *reclaim_thread;
133         unsigned long reclaim_target;   /* number of space that need to be
134                                          * reclaimed.  if it's 0, reclaim spaces
135                                          * used by io_units which are in
136                                          * IO_UNIT_STRIPE_END state (eg, reclaim
137                                          * dones't wait for specific io_unit
138                                          * switching to IO_UNIT_STRIPE_END
139                                          * state) */
140         wait_queue_head_t iounit_wait;
141
142         struct list_head no_space_stripes; /* pending stripes, log has no space */
143         spinlock_t no_space_stripes_lock;
144
145         bool need_cache_flush;
146
147         /* for r5c_cache */
148         enum r5c_journal_mode r5c_journal_mode;
149
150         /* all stripes in r5cache, in the order of seq at sh->log_start */
151         struct list_head stripe_in_journal_list;
152
153         spinlock_t stripe_in_journal_lock;
154         atomic_t stripe_in_journal_count;
155
156         /* to submit async io_units, to fulfill ordering of flush */
157         struct work_struct deferred_io_work;
158         /* to disable write back during in degraded mode */
159         struct work_struct disable_writeback_work;
160
161         /* to for chunk_aligned_read in writeback mode, details below */
162         spinlock_t tree_lock;
163         struct radix_tree_root big_stripe_tree;
164 };
165
166 /*
167  * Enable chunk_aligned_read() with write back cache.
168  *
169  * Each chunk may contain more than one stripe (for example, a 256kB
170  * chunk contains 64 4kB-page, so this chunk contain 64 stripes). For
171  * chunk_aligned_read, these stripes are grouped into one "big_stripe".
172  * For each big_stripe, we count how many stripes of this big_stripe
173  * are in the write back cache. These data are tracked in a radix tree
174  * (big_stripe_tree). We use radix_tree item pointer as the counter.
175  * r5c_tree_index() is used to calculate keys for the radix tree.
176  *
177  * chunk_aligned_read() calls r5c_big_stripe_cached() to look up
178  * big_stripe of each chunk in the tree. If this big_stripe is in the
179  * tree, chunk_aligned_read() aborts. This look up is protected by
180  * rcu_read_lock().
181  *
182  * It is necessary to remember whether a stripe is counted in
183  * big_stripe_tree. Instead of adding new flag, we reuses existing flags:
184  * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE. If either of these
185  * two flags are set, the stripe is counted in big_stripe_tree. This
186  * requires moving set_bit(STRIPE_R5C_PARTIAL_STRIPE) to
187  * r5c_try_caching_write(); and moving clear_bit of
188  * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE to
189  * r5c_finish_stripe_write_out().
190  */
191
192 /*
193  * radix tree requests lowest 2 bits of data pointer to be 2b'00.
194  * So it is necessary to left shift the counter by 2 bits before using it
195  * as data pointer of the tree.
196  */
197 #define R5C_RADIX_COUNT_SHIFT 2
198
199 /*
200  * calculate key for big_stripe_tree
201  *
202  * sect: align_bi->bi_iter.bi_sector or sh->sector
203  */
204 static inline sector_t r5c_tree_index(struct r5conf *conf,
205                                       sector_t sect)
206 {
207         sector_t offset;
208
209         offset = sector_div(sect, conf->chunk_sectors);
210         return sect;
211 }
212
213 /*
214  * an IO range starts from a meta data block and end at the next meta data
215  * block. The io unit's the meta data block tracks data/parity followed it. io
216  * unit is written to log disk with normal write, as we always flush log disk
217  * first and then start move data to raid disks, there is no requirement to
218  * write io unit with FLUSH/FUA
219  */
220 struct r5l_io_unit {
221         struct r5l_log *log;
222
223         struct page *meta_page; /* store meta block */
224         int meta_offset;        /* current offset in meta_page */
225
226         struct bio *current_bio;/* current_bio accepting new data */
227
228         atomic_t pending_stripe;/* how many stripes not flushed to raid */
229         u64 seq;                /* seq number of the metablock */
230         sector_t log_start;     /* where the io_unit starts */
231         sector_t log_end;       /* where the io_unit ends */
232         struct list_head log_sibling; /* log->running_ios */
233         struct list_head stripe_list; /* stripes added to the io_unit */
234
235         int state;
236         bool need_split_bio;
237         struct bio *split_bio;
238
239         unsigned int has_flush:1;               /* include flush request */
240         unsigned int has_fua:1;                 /* include fua request */
241         unsigned int has_null_flush:1;          /* include null flush request */
242         unsigned int has_flush_payload:1;       /* include flush payload  */
243         /*
244          * io isn't sent yet, flush/fua request can only be submitted till it's
245          * the first IO in running_ios list
246          */
247         unsigned int io_deferred:1;
248
249         struct bio_list flush_barriers;   /* size == 0 flush bios */
250 };
251
252 /* r5l_io_unit state */
253 enum r5l_io_unit_state {
254         IO_UNIT_RUNNING = 0,    /* accepting new IO */
255         IO_UNIT_IO_START = 1,   /* io_unit bio start writing to log,
256                                  * don't accepting new bio */
257         IO_UNIT_IO_END = 2,     /* io_unit bio finish writing to log */
258         IO_UNIT_STRIPE_END = 3, /* stripes data finished writing to raid */
259 };
260
261 bool r5c_is_writeback(struct r5l_log *log)
262 {
263         return (log != NULL &&
264                 log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK);
265 }
266
267 static sector_t r5l_ring_add(struct r5l_log *log, sector_t start, sector_t inc)
268 {
269         start += inc;
270         if (start >= log->device_size)
271                 start = start - log->device_size;
272         return start;
273 }
274
275 static sector_t r5l_ring_distance(struct r5l_log *log, sector_t start,
276                                   sector_t end)
277 {
278         if (end >= start)
279                 return end - start;
280         else
281                 return end + log->device_size - start;
282 }
283
284 static bool r5l_has_free_space(struct r5l_log *log, sector_t size)
285 {
286         sector_t used_size;
287
288         used_size = r5l_ring_distance(log, log->last_checkpoint,
289                                         log->log_start);
290
291         return log->device_size > used_size + size;
292 }
293
294 static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
295                                     enum r5l_io_unit_state state)
296 {
297         if (WARN_ON(io->state >= state))
298                 return;
299         io->state = state;
300 }
301
302 static void
303 r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev)
304 {
305         struct bio *wbi, *wbi2;
306
307         wbi = dev->written;
308         dev->written = NULL;
309         while (wbi && wbi->bi_iter.bi_sector <
310                dev->sector + STRIPE_SECTORS) {
311                 wbi2 = r5_next_bio(wbi, dev->sector);
312                 md_write_end(conf->mddev);
313                 bio_endio(wbi);
314                 wbi = wbi2;
315         }
316 }
317
318 void r5c_handle_cached_data_endio(struct r5conf *conf,
319                                   struct stripe_head *sh, int disks)
320 {
321         int i;
322
323         for (i = sh->disks; i--; ) {
324                 if (sh->dev[i].written) {
325                         set_bit(R5_UPTODATE, &sh->dev[i].flags);
326                         r5c_return_dev_pending_writes(conf, &sh->dev[i]);
327                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
328                                         STRIPE_SECTORS,
329                                         !test_bit(STRIPE_DEGRADED, &sh->state),
330                                         0);
331                 }
332         }
333 }
334
335 void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
336
337 /* Check whether we should flush some stripes to free up stripe cache */
338 void r5c_check_stripe_cache_usage(struct r5conf *conf)
339 {
340         int total_cached;
341
342         if (!r5c_is_writeback(conf->log))
343                 return;
344
345         total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
346                 atomic_read(&conf->r5c_cached_full_stripes);
347
348         /*
349          * The following condition is true for either of the following:
350          *   - stripe cache pressure high:
351          *          total_cached > 3/4 min_nr_stripes ||
352          *          empty_inactive_list_nr > 0
353          *   - stripe cache pressure moderate:
354          *          total_cached > 1/2 min_nr_stripes
355          */
356         if (total_cached > conf->min_nr_stripes * 1 / 2 ||
357             atomic_read(&conf->empty_inactive_list_nr) > 0)
358                 r5l_wake_reclaim(conf->log, 0);
359 }
360
361 /*
362  * flush cache when there are R5C_FULL_STRIPE_FLUSH_BATCH or more full
363  * stripes in the cache
364  */
365 void r5c_check_cached_full_stripe(struct r5conf *conf)
366 {
367         if (!r5c_is_writeback(conf->log))
368                 return;
369
370         /*
371          * wake up reclaim for R5C_FULL_STRIPE_FLUSH_BATCH cached stripes
372          * or a full stripe (chunk size / 4k stripes).
373          */
374         if (atomic_read(&conf->r5c_cached_full_stripes) >=
375             min(R5C_FULL_STRIPE_FLUSH_BATCH(conf),
376                 conf->chunk_sectors >> STRIPE_SHIFT))
377                 r5l_wake_reclaim(conf->log, 0);
378 }
379
380 /*
381  * Total log space (in sectors) needed to flush all data in cache
382  *
383  * To avoid deadlock due to log space, it is necessary to reserve log
384  * space to flush critical stripes (stripes that occupying log space near
385  * last_checkpoint). This function helps check how much log space is
386  * required to flush all cached stripes.
387  *
388  * To reduce log space requirements, two mechanisms are used to give cache
389  * flush higher priorities:
390  *    1. In handle_stripe_dirtying() and schedule_reconstruction(),
391  *       stripes ALREADY in journal can be flushed w/o pending writes;
392  *    2. In r5l_write_stripe() and r5c_cache_data(), stripes NOT in journal
393  *       can be delayed (r5l_add_no_space_stripe).
394  *
395  * In cache flush, the stripe goes through 1 and then 2. For a stripe that
396  * already passed 1, flushing it requires at most (conf->max_degraded + 1)
397  * pages of journal space. For stripes that has not passed 1, flushing it
398  * requires (conf->raid_disks + 1) pages of journal space. There are at
399  * most (conf->group_cnt + 1) stripe that passed 1. So total journal space
400  * required to flush all cached stripes (in pages) is:
401  *
402  *     (stripe_in_journal_count - group_cnt - 1) * (max_degraded + 1) +
403  *     (group_cnt + 1) * (raid_disks + 1)
404  * or
405  *     (stripe_in_journal_count) * (max_degraded + 1) +
406  *     (group_cnt + 1) * (raid_disks - max_degraded)
407  */
408 static sector_t r5c_log_required_to_flush_cache(struct r5conf *conf)
409 {
410         struct r5l_log *log = conf->log;
411
412         if (!r5c_is_writeback(log))
413                 return 0;
414
415         return BLOCK_SECTORS *
416                 ((conf->max_degraded + 1) * atomic_read(&log->stripe_in_journal_count) +
417                  (conf->raid_disks - conf->max_degraded) * (conf->group_cnt + 1));
418 }
419
420 /*
421  * evaluate log space usage and update R5C_LOG_TIGHT and R5C_LOG_CRITICAL
422  *
423  * R5C_LOG_TIGHT is set when free space on the log device is less than 3x of
424  * reclaim_required_space. R5C_LOG_CRITICAL is set when free space on the log
425  * device is less than 2x of reclaim_required_space.
426  */
427 static inline void r5c_update_log_state(struct r5l_log *log)
428 {
429         struct r5conf *conf = log->rdev->mddev->private;
430         sector_t free_space;
431         sector_t reclaim_space;
432         bool wake_reclaim = false;
433
434         if (!r5c_is_writeback(log))
435                 return;
436
437         free_space = r5l_ring_distance(log, log->log_start,
438                                        log->last_checkpoint);
439         reclaim_space = r5c_log_required_to_flush_cache(conf);
440         if (free_space < 2 * reclaim_space)
441                 set_bit(R5C_LOG_CRITICAL, &conf->cache_state);
442         else {
443                 if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
444                         wake_reclaim = true;
445                 clear_bit(R5C_LOG_CRITICAL, &conf->cache_state);
446         }
447         if (free_space < 3 * reclaim_space)
448                 set_bit(R5C_LOG_TIGHT, &conf->cache_state);
449         else
450                 clear_bit(R5C_LOG_TIGHT, &conf->cache_state);
451
452         if (wake_reclaim)
453                 r5l_wake_reclaim(log, 0);
454 }
455
456 /*
457  * Put the stripe into writing-out phase by clearing STRIPE_R5C_CACHING.
458  * This function should only be called in write-back mode.
459  */
460 void r5c_make_stripe_write_out(struct stripe_head *sh)
461 {
462         struct r5conf *conf = sh->raid_conf;
463         struct r5l_log *log = conf->log;
464
465         BUG_ON(!r5c_is_writeback(log));
466
467         WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
468         clear_bit(STRIPE_R5C_CACHING, &sh->state);
469
470         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
471                 atomic_inc(&conf->preread_active_stripes);
472 }
473
474 static void r5c_handle_data_cached(struct stripe_head *sh)
475 {
476         int i;
477
478         for (i = sh->disks; i--; )
479                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
480                         set_bit(R5_InJournal, &sh->dev[i].flags);
481                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
482                 }
483         clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
484 }
485
486 /*
487  * this journal write must contain full parity,
488  * it may also contain some data pages
489  */
490 static void r5c_handle_parity_cached(struct stripe_head *sh)
491 {
492         int i;
493
494         for (i = sh->disks; i--; )
495                 if (test_bit(R5_InJournal, &sh->dev[i].flags))
496                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
497 }
498
499 /*
500  * Setting proper flags after writing (or flushing) data and/or parity to the
501  * log device. This is called from r5l_log_endio() or r5l_log_flush_endio().
502  */
503 static void r5c_finish_cache_stripe(struct stripe_head *sh)
504 {
505         struct r5l_log *log = sh->raid_conf->log;
506
507         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
508                 BUG_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
509                 /*
510                  * Set R5_InJournal for parity dev[pd_idx]. This means
511                  * all data AND parity in the journal. For RAID 6, it is
512                  * NOT necessary to set the flag for dev[qd_idx], as the
513                  * two parities are written out together.
514                  */
515                 set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
516         } else if (test_bit(STRIPE_R5C_CACHING, &sh->state)) {
517                 r5c_handle_data_cached(sh);
518         } else {
519                 r5c_handle_parity_cached(sh);
520                 set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
521         }
522 }
523
524 static void r5l_io_run_stripes(struct r5l_io_unit *io)
525 {
526         struct stripe_head *sh, *next;
527
528         list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
529                 list_del_init(&sh->log_list);
530
531                 r5c_finish_cache_stripe(sh);
532
533                 set_bit(STRIPE_HANDLE, &sh->state);
534                 raid5_release_stripe(sh);
535         }
536 }
537
538 static void r5l_log_run_stripes(struct r5l_log *log)
539 {
540         struct r5l_io_unit *io, *next;
541
542         lockdep_assert_held(&log->io_list_lock);
543
544         list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
545                 /* don't change list order */
546                 if (io->state < IO_UNIT_IO_END)
547                         break;
548
549                 list_move_tail(&io->log_sibling, &log->finished_ios);
550                 r5l_io_run_stripes(io);
551         }
552 }
553
554 static void r5l_move_to_end_ios(struct r5l_log *log)
555 {
556         struct r5l_io_unit *io, *next;
557
558         lockdep_assert_held(&log->io_list_lock);
559
560         list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
561                 /* don't change list order */
562                 if (io->state < IO_UNIT_IO_END)
563                         break;
564                 list_move_tail(&io->log_sibling, &log->io_end_ios);
565         }
566 }
567
568 static void __r5l_stripe_write_finished(struct r5l_io_unit *io);
569 static void r5l_log_endio(struct bio *bio)
570 {
571         struct r5l_io_unit *io = bio->bi_private;
572         struct r5l_io_unit *io_deferred;
573         struct r5l_log *log = io->log;
574         unsigned long flags;
575         bool has_null_flush;
576         bool has_flush_payload;
577
578         if (bio->bi_status)
579                 md_error(log->rdev->mddev, log->rdev);
580
581         bio_put(bio);
582         mempool_free(io->meta_page, log->meta_pool);
583
584         spin_lock_irqsave(&log->io_list_lock, flags);
585         __r5l_set_io_unit_state(io, IO_UNIT_IO_END);
586
587         /*
588          * if the io doesn't not have null_flush or flush payload,
589          * it is not safe to access it after releasing io_list_lock.
590          * Therefore, it is necessary to check the condition with
591          * the lock held.
592          */
593         has_null_flush = io->has_null_flush;
594         has_flush_payload = io->has_flush_payload;
595
596         if (log->need_cache_flush && !list_empty(&io->stripe_list))
597                 r5l_move_to_end_ios(log);
598         else
599                 r5l_log_run_stripes(log);
600         if (!list_empty(&log->running_ios)) {
601                 /*
602                  * FLUSH/FUA io_unit is deferred because of ordering, now we
603                  * can dispatch it
604                  */
605                 io_deferred = list_first_entry(&log->running_ios,
606                                                struct r5l_io_unit, log_sibling);
607                 if (io_deferred->io_deferred)
608                         schedule_work(&log->deferred_io_work);
609         }
610
611         spin_unlock_irqrestore(&log->io_list_lock, flags);
612
613         if (log->need_cache_flush)
614                 md_wakeup_thread(log->rdev->mddev->thread);
615
616         /* finish flush only io_unit and PAYLOAD_FLUSH only io_unit */
617         if (has_null_flush) {
618                 struct bio *bi;
619
620                 WARN_ON(bio_list_empty(&io->flush_barriers));
621                 while ((bi = bio_list_pop(&io->flush_barriers)) != NULL) {
622                         bio_endio(bi);
623                         if (atomic_dec_and_test(&io->pending_stripe)) {
624                                 __r5l_stripe_write_finished(io);
625                                 return;
626                         }
627                 }
628         }
629         /* decrease pending_stripe for flush payload */
630         if (has_flush_payload)
631                 if (atomic_dec_and_test(&io->pending_stripe))
632                         __r5l_stripe_write_finished(io);
633 }
634
635 static void r5l_do_submit_io(struct r5l_log *log, struct r5l_io_unit *io)
636 {
637         unsigned long flags;
638
639         spin_lock_irqsave(&log->io_list_lock, flags);
640         __r5l_set_io_unit_state(io, IO_UNIT_IO_START);
641         spin_unlock_irqrestore(&log->io_list_lock, flags);
642
643         /*
644          * In case of journal device failures, submit_bio will get error
645          * and calls endio, then active stripes will continue write
646          * process. Therefore, it is not necessary to check Faulty bit
647          * of journal device here.
648          *
649          * We can't check split_bio after current_bio is submitted. If
650          * io->split_bio is null, after current_bio is submitted, current_bio
651          * might already be completed and the io_unit is freed. We submit
652          * split_bio first to avoid the issue.
653          */
654         if (io->split_bio) {
655                 if (io->has_flush)
656                         io->split_bio->bi_opf |= REQ_PREFLUSH;
657                 if (io->has_fua)
658                         io->split_bio->bi_opf |= REQ_FUA;
659                 submit_bio(io->split_bio);
660         }
661
662         if (io->has_flush)
663                 io->current_bio->bi_opf |= REQ_PREFLUSH;
664         if (io->has_fua)
665                 io->current_bio->bi_opf |= REQ_FUA;
666         submit_bio(io->current_bio);
667 }
668
669 /* deferred io_unit will be dispatched here */
670 static void r5l_submit_io_async(struct work_struct *work)
671 {
672         struct r5l_log *log = container_of(work, struct r5l_log,
673                                            deferred_io_work);
674         struct r5l_io_unit *io = NULL;
675         unsigned long flags;
676
677         spin_lock_irqsave(&log->io_list_lock, flags);
678         if (!list_empty(&log->running_ios)) {
679                 io = list_first_entry(&log->running_ios, struct r5l_io_unit,
680                                       log_sibling);
681                 if (!io->io_deferred)
682                         io = NULL;
683                 else
684                         io->io_deferred = 0;
685         }
686         spin_unlock_irqrestore(&log->io_list_lock, flags);
687         if (io)
688                 r5l_do_submit_io(log, io);
689 }
690
691 static void r5c_disable_writeback_async(struct work_struct *work)
692 {
693         struct r5l_log *log = container_of(work, struct r5l_log,
694                                            disable_writeback_work);
695         struct mddev *mddev = log->rdev->mddev;
696         struct r5conf *conf = mddev->private;
697         int locked = 0;
698
699         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
700                 return;
701         pr_info("md/raid:%s: Disabling writeback cache for degraded array.\n",
702                 mdname(mddev));
703
704         /* wait superblock change before suspend */
705         wait_event(mddev->sb_wait,
706                    conf->log == NULL ||
707                    (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) &&
708                     (locked = mddev_trylock(mddev))));
709         if (locked) {
710                 mddev_suspend(mddev);
711                 log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
712                 mddev_resume(mddev);
713                 mddev_unlock(mddev);
714         }
715 }
716
717 static void r5l_submit_current_io(struct r5l_log *log)
718 {
719         struct r5l_io_unit *io = log->current_io;
720         struct bio *bio;
721         struct r5l_meta_block *block;
722         unsigned long flags;
723         u32 crc;
724         bool do_submit = true;
725
726         if (!io)
727                 return;
728
729         block = page_address(io->meta_page);
730         block->meta_size = cpu_to_le32(io->meta_offset);
731         crc = crc32c_le(log->uuid_checksum, block, PAGE_SIZE);
732         block->checksum = cpu_to_le32(crc);
733         bio = io->current_bio;
734
735         log->current_io = NULL;
736         spin_lock_irqsave(&log->io_list_lock, flags);
737         if (io->has_flush || io->has_fua) {
738                 if (io != list_first_entry(&log->running_ios,
739                                            struct r5l_io_unit, log_sibling)) {
740                         io->io_deferred = 1;
741                         do_submit = false;
742                 }
743         }
744         spin_unlock_irqrestore(&log->io_list_lock, flags);
745         if (do_submit)
746                 r5l_do_submit_io(log, io);
747 }
748
749 static struct bio *r5l_bio_alloc(struct r5l_log *log)
750 {
751         struct bio *bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, log->bs);
752
753         bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
754         bio_set_dev(bio, log->rdev->bdev);
755         bio->bi_iter.bi_sector = log->rdev->data_offset + log->log_start;
756
757         return bio;
758 }
759
760 static void r5_reserve_log_entry(struct r5l_log *log, struct r5l_io_unit *io)
761 {
762         log->log_start = r5l_ring_add(log, log->log_start, BLOCK_SECTORS);
763
764         r5c_update_log_state(log);
765         /*
766          * If we filled up the log device start from the beginning again,
767          * which will require a new bio.
768          *
769          * Note: for this to work properly the log size needs to me a multiple
770          * of BLOCK_SECTORS.
771          */
772         if (log->log_start == 0)
773                 io->need_split_bio = true;
774
775         io->log_end = log->log_start;
776 }
777
778 static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
779 {
780         struct r5l_io_unit *io;
781         struct r5l_meta_block *block;
782
783         io = mempool_alloc(log->io_pool, GFP_ATOMIC);
784         if (!io)
785                 return NULL;
786         memset(io, 0, sizeof(*io));
787
788         io->log = log;
789         INIT_LIST_HEAD(&io->log_sibling);
790         INIT_LIST_HEAD(&io->stripe_list);
791         bio_list_init(&io->flush_barriers);
792         io->state = IO_UNIT_RUNNING;
793
794         io->meta_page = mempool_alloc(log->meta_pool, GFP_NOIO);
795         block = page_address(io->meta_page);
796         clear_page(block);
797         block->magic = cpu_to_le32(R5LOG_MAGIC);
798         block->version = R5LOG_VERSION;
799         block->seq = cpu_to_le64(log->seq);
800         block->position = cpu_to_le64(log->log_start);
801
802         io->log_start = log->log_start;
803         io->meta_offset = sizeof(struct r5l_meta_block);
804         io->seq = log->seq++;
805
806         io->current_bio = r5l_bio_alloc(log);
807         io->current_bio->bi_end_io = r5l_log_endio;
808         io->current_bio->bi_private = io;
809         bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
810
811         r5_reserve_log_entry(log, io);
812
813         spin_lock_irq(&log->io_list_lock);
814         list_add_tail(&io->log_sibling, &log->running_ios);
815         spin_unlock_irq(&log->io_list_lock);
816
817         return io;
818 }
819
820 static int r5l_get_meta(struct r5l_log *log, unsigned int payload_size)
821 {
822         if (log->current_io &&
823             log->current_io->meta_offset + payload_size > PAGE_SIZE)
824                 r5l_submit_current_io(log);
825
826         if (!log->current_io) {
827                 log->current_io = r5l_new_meta(log);
828                 if (!log->current_io)
829                         return -ENOMEM;
830         }
831
832         return 0;
833 }
834
835 static void r5l_append_payload_meta(struct r5l_log *log, u16 type,
836                                     sector_t location,
837                                     u32 checksum1, u32 checksum2,
838                                     bool checksum2_valid)
839 {
840         struct r5l_io_unit *io = log->current_io;
841         struct r5l_payload_data_parity *payload;
842
843         payload = page_address(io->meta_page) + io->meta_offset;
844         payload->header.type = cpu_to_le16(type);
845         payload->header.flags = cpu_to_le16(0);
846         payload->size = cpu_to_le32((1 + !!checksum2_valid) <<
847                                     (PAGE_SHIFT - 9));
848         payload->location = cpu_to_le64(location);
849         payload->checksum[0] = cpu_to_le32(checksum1);
850         if (checksum2_valid)
851                 payload->checksum[1] = cpu_to_le32(checksum2);
852
853         io->meta_offset += sizeof(struct r5l_payload_data_parity) +
854                 sizeof(__le32) * (1 + !!checksum2_valid);
855 }
856
857 static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
858 {
859         struct r5l_io_unit *io = log->current_io;
860
861         if (io->need_split_bio) {
862                 BUG_ON(io->split_bio);
863                 io->split_bio = io->current_bio;
864                 io->current_bio = r5l_bio_alloc(log);
865                 bio_chain(io->current_bio, io->split_bio);
866                 io->need_split_bio = false;
867         }
868
869         if (!bio_add_page(io->current_bio, page, PAGE_SIZE, 0))
870                 BUG();
871
872         r5_reserve_log_entry(log, io);
873 }
874
875 static void r5l_append_flush_payload(struct r5l_log *log, sector_t sect)
876 {
877         struct mddev *mddev = log->rdev->mddev;
878         struct r5conf *conf = mddev->private;
879         struct r5l_io_unit *io;
880         struct r5l_payload_flush *payload;
881         int meta_size;
882
883         /*
884          * payload_flush requires extra writes to the journal.
885          * To avoid handling the extra IO in quiesce, just skip
886          * flush_payload
887          */
888         if (conf->quiesce)
889                 return;
890
891         mutex_lock(&log->io_mutex);
892         meta_size = sizeof(struct r5l_payload_flush) + sizeof(__le64);
893
894         if (r5l_get_meta(log, meta_size)) {
895                 mutex_unlock(&log->io_mutex);
896                 return;
897         }
898
899         /* current implementation is one stripe per flush payload */
900         io = log->current_io;
901         payload = page_address(io->meta_page) + io->meta_offset;
902         payload->header.type = cpu_to_le16(R5LOG_PAYLOAD_FLUSH);
903         payload->header.flags = cpu_to_le16(0);
904         payload->size = cpu_to_le32(sizeof(__le64));
905         payload->flush_stripes[0] = cpu_to_le64(sect);
906         io->meta_offset += meta_size;
907         /* multiple flush payloads count as one pending_stripe */
908         if (!io->has_flush_payload) {
909                 io->has_flush_payload = 1;
910                 atomic_inc(&io->pending_stripe);
911         }
912         mutex_unlock(&log->io_mutex);
913 }
914
915 static int r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
916                            int data_pages, int parity_pages)
917 {
918         int i;
919         int meta_size;
920         int ret;
921         struct r5l_io_unit *io;
922
923         meta_size =
924                 ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
925                  * data_pages) +
926                 sizeof(struct r5l_payload_data_parity) +
927                 sizeof(__le32) * parity_pages;
928
929         ret = r5l_get_meta(log, meta_size);
930         if (ret)
931                 return ret;
932
933         io = log->current_io;
934
935         if (test_and_clear_bit(STRIPE_R5C_PREFLUSH, &sh->state))
936                 io->has_flush = 1;
937
938         for (i = 0; i < sh->disks; i++) {
939                 if (!test_bit(R5_Wantwrite, &sh->dev[i].flags) ||
940                     test_bit(R5_InJournal, &sh->dev[i].flags))
941                         continue;
942                 if (i == sh->pd_idx || i == sh->qd_idx)
943                         continue;
944                 if (test_bit(R5_WantFUA, &sh->dev[i].flags) &&
945                     log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK) {
946                         io->has_fua = 1;
947                         /*
948                          * we need to flush journal to make sure recovery can
949                          * reach the data with fua flag
950                          */
951                         io->has_flush = 1;
952                 }
953                 r5l_append_payload_meta(log, R5LOG_PAYLOAD_DATA,
954                                         raid5_compute_blocknr(sh, i, 0),
955                                         sh->dev[i].log_checksum, 0, false);
956                 r5l_append_payload_page(log, sh->dev[i].page);
957         }
958
959         if (parity_pages == 2) {
960                 r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
961                                         sh->sector, sh->dev[sh->pd_idx].log_checksum,
962                                         sh->dev[sh->qd_idx].log_checksum, true);
963                 r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
964                 r5l_append_payload_page(log, sh->dev[sh->qd_idx].page);
965         } else if (parity_pages == 1) {
966                 r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
967                                         sh->sector, sh->dev[sh->pd_idx].log_checksum,
968                                         0, false);
969                 r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
970         } else  /* Just writing data, not parity, in caching phase */
971                 BUG_ON(parity_pages != 0);
972
973         list_add_tail(&sh->log_list, &io->stripe_list);
974         atomic_inc(&io->pending_stripe);
975         sh->log_io = io;
976
977         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
978                 return 0;
979
980         if (sh->log_start == MaxSector) {
981                 BUG_ON(!list_empty(&sh->r5c));
982                 sh->log_start = io->log_start;
983                 spin_lock_irq(&log->stripe_in_journal_lock);
984                 list_add_tail(&sh->r5c,
985                               &log->stripe_in_journal_list);
986                 spin_unlock_irq(&log->stripe_in_journal_lock);
987                 atomic_inc(&log->stripe_in_journal_count);
988         }
989         return 0;
990 }
991
992 /* add stripe to no_space_stripes, and then wake up reclaim */
993 static inline void r5l_add_no_space_stripe(struct r5l_log *log,
994                                            struct stripe_head *sh)
995 {
996         spin_lock(&log->no_space_stripes_lock);
997         list_add_tail(&sh->log_list, &log->no_space_stripes);
998         spin_unlock(&log->no_space_stripes_lock);
999 }
1000
1001 /*
1002  * running in raid5d, where reclaim could wait for raid5d too (when it flushes
1003  * data from log to raid disks), so we shouldn't wait for reclaim here
1004  */
1005 int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
1006 {
1007         struct r5conf *conf = sh->raid_conf;
1008         int write_disks = 0;
1009         int data_pages, parity_pages;
1010         int reserve;
1011         int i;
1012         int ret = 0;
1013         bool wake_reclaim = false;
1014
1015         if (!log)
1016                 return -EAGAIN;
1017         /* Don't support stripe batch */
1018         if (sh->log_io || !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
1019             test_bit(STRIPE_SYNCING, &sh->state)) {
1020                 /* the stripe is written to log, we start writing it to raid */
1021                 clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
1022                 return -EAGAIN;
1023         }
1024
1025         WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
1026
1027         for (i = 0; i < sh->disks; i++) {
1028                 void *addr;
1029
1030                 if (!test_bit(R5_Wantwrite, &sh->dev[i].flags) ||
1031                     test_bit(R5_InJournal, &sh->dev[i].flags))
1032                         continue;
1033
1034                 write_disks++;
1035                 /* checksum is already calculated in last run */
1036                 if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
1037                         continue;
1038                 addr = kmap_atomic(sh->dev[i].page);
1039                 sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
1040                                                     addr, PAGE_SIZE);
1041                 kunmap_atomic(addr);
1042         }
1043         parity_pages = 1 + !!(sh->qd_idx >= 0);
1044         data_pages = write_disks - parity_pages;
1045
1046         set_bit(STRIPE_LOG_TRAPPED, &sh->state);
1047         /*
1048          * The stripe must enter state machine again to finish the write, so
1049          * don't delay.
1050          */
1051         clear_bit(STRIPE_DELAYED, &sh->state);
1052         atomic_inc(&sh->count);
1053
1054         mutex_lock(&log->io_mutex);
1055         /* meta + data */
1056         reserve = (1 + write_disks) << (PAGE_SHIFT - 9);
1057
1058         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
1059                 if (!r5l_has_free_space(log, reserve)) {
1060                         r5l_add_no_space_stripe(log, sh);
1061                         wake_reclaim = true;
1062                 } else {
1063                         ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
1064                         if (ret) {
1065                                 spin_lock_irq(&log->io_list_lock);
1066                                 list_add_tail(&sh->log_list,
1067                                               &log->no_mem_stripes);
1068                                 spin_unlock_irq(&log->io_list_lock);
1069                         }
1070                 }
1071         } else {  /* R5C_JOURNAL_MODE_WRITE_BACK */
1072                 /*
1073                  * log space critical, do not process stripes that are
1074                  * not in cache yet (sh->log_start == MaxSector).
1075                  */
1076                 if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
1077                     sh->log_start == MaxSector) {
1078                         r5l_add_no_space_stripe(log, sh);
1079                         wake_reclaim = true;
1080                         reserve = 0;
1081                 } else if (!r5l_has_free_space(log, reserve)) {
1082                         if (sh->log_start == log->last_checkpoint)
1083                                 BUG();
1084                         else
1085                                 r5l_add_no_space_stripe(log, sh);
1086                 } else {
1087                         ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
1088                         if (ret) {
1089                                 spin_lock_irq(&log->io_list_lock);
1090                                 list_add_tail(&sh->log_list,
1091                                               &log->no_mem_stripes);
1092                                 spin_unlock_irq(&log->io_list_lock);
1093                         }
1094                 }
1095         }
1096
1097         mutex_unlock(&log->io_mutex);
1098         if (wake_reclaim)
1099                 r5l_wake_reclaim(log, reserve);
1100         return 0;
1101 }
1102
1103 void r5l_write_stripe_run(struct r5l_log *log)
1104 {
1105         if (!log)
1106                 return;
1107         mutex_lock(&log->io_mutex);
1108         r5l_submit_current_io(log);
1109         mutex_unlock(&log->io_mutex);
1110 }
1111
1112 int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio)
1113 {
1114         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
1115                 /*
1116                  * in write through (journal only)
1117                  * we flush log disk cache first, then write stripe data to
1118                  * raid disks. So if bio is finished, the log disk cache is
1119                  * flushed already. The recovery guarantees we can recovery
1120                  * the bio from log disk, so we don't need to flush again
1121                  */
1122                 if (bio->bi_iter.bi_size == 0) {
1123                         bio_endio(bio);
1124                         return 0;
1125                 }
1126                 bio->bi_opf &= ~REQ_PREFLUSH;
1127         } else {
1128                 /* write back (with cache) */
1129                 if (bio->bi_iter.bi_size == 0) {
1130                         mutex_lock(&log->io_mutex);
1131                         r5l_get_meta(log, 0);
1132                         bio_list_add(&log->current_io->flush_barriers, bio);
1133                         log->current_io->has_flush = 1;
1134                         log->current_io->has_null_flush = 1;
1135                         atomic_inc(&log->current_io->pending_stripe);
1136                         r5l_submit_current_io(log);
1137                         mutex_unlock(&log->io_mutex);
1138                         return 0;
1139                 }
1140         }
1141         return -EAGAIN;
1142 }
1143
1144 /* This will run after log space is reclaimed */
1145 static void r5l_run_no_space_stripes(struct r5l_log *log)
1146 {
1147         struct stripe_head *sh;
1148
1149         spin_lock(&log->no_space_stripes_lock);
1150         while (!list_empty(&log->no_space_stripes)) {
1151                 sh = list_first_entry(&log->no_space_stripes,
1152                                       struct stripe_head, log_list);
1153                 list_del_init(&sh->log_list);
1154                 set_bit(STRIPE_HANDLE, &sh->state);
1155                 raid5_release_stripe(sh);
1156         }
1157         spin_unlock(&log->no_space_stripes_lock);
1158 }
1159
1160 /*
1161  * calculate new last_checkpoint
1162  * for write through mode, returns log->next_checkpoint
1163  * for write back, returns log_start of first sh in stripe_in_journal_list
1164  */
1165 static sector_t r5c_calculate_new_cp(struct r5conf *conf)
1166 {
1167         struct stripe_head *sh;
1168         struct r5l_log *log = conf->log;
1169         sector_t new_cp;
1170         unsigned long flags;
1171
1172         if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
1173                 return log->next_checkpoint;
1174
1175         spin_lock_irqsave(&log->stripe_in_journal_lock, flags);
1176         if (list_empty(&conf->log->stripe_in_journal_list)) {
1177                 /* all stripes flushed */
1178                 spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
1179                 return log->next_checkpoint;
1180         }
1181         sh = list_first_entry(&conf->log->stripe_in_journal_list,
1182                               struct stripe_head, r5c);
1183         new_cp = sh->log_start;
1184         spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
1185         return new_cp;
1186 }
1187
1188 static sector_t r5l_reclaimable_space(struct r5l_log *log)
1189 {
1190         struct r5conf *conf = log->rdev->mddev->private;
1191
1192         return r5l_ring_distance(log, log->last_checkpoint,
1193                                  r5c_calculate_new_cp(conf));
1194 }
1195
1196 static void r5l_run_no_mem_stripe(struct r5l_log *log)
1197 {
1198         struct stripe_head *sh;
1199
1200         lockdep_assert_held(&log->io_list_lock);
1201
1202         if (!list_empty(&log->no_mem_stripes)) {
1203                 sh = list_first_entry(&log->no_mem_stripes,
1204                                       struct stripe_head, log_list);
1205                 list_del_init(&sh->log_list);
1206                 set_bit(STRIPE_HANDLE, &sh->state);
1207                 raid5_release_stripe(sh);
1208         }
1209 }
1210
1211 static bool r5l_complete_finished_ios(struct r5l_log *log)
1212 {
1213         struct r5l_io_unit *io, *next;
1214         bool found = false;
1215
1216         lockdep_assert_held(&log->io_list_lock);
1217
1218         list_for_each_entry_safe(io, next, &log->finished_ios, log_sibling) {
1219                 /* don't change list order */
1220                 if (io->state < IO_UNIT_STRIPE_END)
1221                         break;
1222
1223                 log->next_checkpoint = io->log_start;
1224
1225                 list_del(&io->log_sibling);
1226                 mempool_free(io, log->io_pool);
1227                 r5l_run_no_mem_stripe(log);
1228
1229                 found = true;
1230         }
1231
1232         return found;
1233 }
1234
1235 static void __r5l_stripe_write_finished(struct r5l_io_unit *io)
1236 {
1237         struct r5l_log *log = io->log;
1238         struct r5conf *conf = log->rdev->mddev->private;
1239         unsigned long flags;
1240
1241         spin_lock_irqsave(&log->io_list_lock, flags);
1242         __r5l_set_io_unit_state(io, IO_UNIT_STRIPE_END);
1243
1244         if (!r5l_complete_finished_ios(log)) {
1245                 spin_unlock_irqrestore(&log->io_list_lock, flags);
1246                 return;
1247         }
1248
1249         if (r5l_reclaimable_space(log) > log->max_free_space ||
1250             test_bit(R5C_LOG_TIGHT, &conf->cache_state))
1251                 r5l_wake_reclaim(log, 0);
1252
1253         spin_unlock_irqrestore(&log->io_list_lock, flags);
1254         wake_up(&log->iounit_wait);
1255 }
1256
1257 void r5l_stripe_write_finished(struct stripe_head *sh)
1258 {
1259         struct r5l_io_unit *io;
1260
1261         io = sh->log_io;
1262         sh->log_io = NULL;
1263
1264         if (io && atomic_dec_and_test(&io->pending_stripe))
1265                 __r5l_stripe_write_finished(io);
1266 }
1267
1268 static void r5l_log_flush_endio(struct bio *bio)
1269 {
1270         struct r5l_log *log = container_of(bio, struct r5l_log,
1271                 flush_bio);
1272         unsigned long flags;
1273         struct r5l_io_unit *io;
1274
1275         if (bio->bi_status)
1276                 md_error(log->rdev->mddev, log->rdev);
1277
1278         spin_lock_irqsave(&log->io_list_lock, flags);
1279         list_for_each_entry(io, &log->flushing_ios, log_sibling)
1280                 r5l_io_run_stripes(io);
1281         list_splice_tail_init(&log->flushing_ios, &log->finished_ios);
1282         spin_unlock_irqrestore(&log->io_list_lock, flags);
1283 }
1284
1285 /*
1286  * Starting dispatch IO to raid.
1287  * io_unit(meta) consists of a log. There is one situation we want to avoid. A
1288  * broken meta in the middle of a log causes recovery can't find meta at the
1289  * head of log. If operations require meta at the head persistent in log, we
1290  * must make sure meta before it persistent in log too. A case is:
1291  *
1292  * stripe data/parity is in log, we start write stripe to raid disks. stripe
1293  * data/parity must be persistent in log before we do the write to raid disks.
1294  *
1295  * The solution is we restrictly maintain io_unit list order. In this case, we
1296  * only write stripes of an io_unit to raid disks till the io_unit is the first
1297  * one whose data/parity is in log.
1298  */
1299 void r5l_flush_stripe_to_raid(struct r5l_log *log)
1300 {
1301         bool do_flush;
1302
1303         if (!log || !log->need_cache_flush)
1304                 return;
1305
1306         spin_lock_irq(&log->io_list_lock);
1307         /* flush bio is running */
1308         if (!list_empty(&log->flushing_ios)) {
1309                 spin_unlock_irq(&log->io_list_lock);
1310                 return;
1311         }
1312         list_splice_tail_init(&log->io_end_ios, &log->flushing_ios);
1313         do_flush = !list_empty(&log->flushing_ios);
1314         spin_unlock_irq(&log->io_list_lock);
1315
1316         if (!do_flush)
1317                 return;
1318         bio_reset(&log->flush_bio);
1319         bio_set_dev(&log->flush_bio, log->rdev->bdev);
1320         log->flush_bio.bi_end_io = r5l_log_flush_endio;
1321         log->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
1322         submit_bio(&log->flush_bio);
1323 }
1324
1325 static void r5l_write_super(struct r5l_log *log, sector_t cp);
1326 static void r5l_write_super_and_discard_space(struct r5l_log *log,
1327         sector_t end)
1328 {
1329         struct block_device *bdev = log->rdev->bdev;
1330         struct mddev *mddev;
1331
1332         r5l_write_super(log, end);
1333
1334         if (!blk_queue_discard(bdev_get_queue(bdev)))
1335                 return;
1336
1337         mddev = log->rdev->mddev;
1338         /*
1339          * Discard could zero data, so before discard we must make sure
1340          * superblock is updated to new log tail. Updating superblock (either
1341          * directly call md_update_sb() or depend on md thread) must hold
1342          * reconfig mutex. On the other hand, raid5_quiesce is called with
1343          * reconfig_mutex hold. The first step of raid5_quiesce() is waitting
1344          * for all IO finish, hence waitting for reclaim thread, while reclaim
1345          * thread is calling this function and waitting for reconfig mutex. So
1346          * there is a deadlock. We workaround this issue with a trylock.
1347          * FIXME: we could miss discard if we can't take reconfig mutex
1348          */
1349         set_mask_bits(&mddev->sb_flags, 0,
1350                 BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
1351         if (!mddev_trylock(mddev))
1352                 return;
1353         md_update_sb(mddev, 1);
1354         mddev_unlock(mddev);
1355
1356         /* discard IO error really doesn't matter, ignore it */
1357         if (log->last_checkpoint < end) {
1358                 blkdev_issue_discard(bdev,
1359                                 log->last_checkpoint + log->rdev->data_offset,
1360                                 end - log->last_checkpoint, GFP_NOIO, 0);
1361         } else {
1362                 blkdev_issue_discard(bdev,
1363                                 log->last_checkpoint + log->rdev->data_offset,
1364                                 log->device_size - log->last_checkpoint,
1365                                 GFP_NOIO, 0);
1366                 blkdev_issue_discard(bdev, log->rdev->data_offset, end,
1367                                 GFP_NOIO, 0);
1368         }
1369 }
1370
1371 /*
1372  * r5c_flush_stripe moves stripe from cached list to handle_list. When called,
1373  * the stripe must be on r5c_cached_full_stripes or r5c_cached_partial_stripes.
1374  *
1375  * must hold conf->device_lock
1376  */
1377 static void r5c_flush_stripe(struct r5conf *conf, struct stripe_head *sh)
1378 {
1379         BUG_ON(list_empty(&sh->lru));
1380         BUG_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
1381         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
1382
1383         /*
1384          * The stripe is not ON_RELEASE_LIST, so it is safe to call
1385          * raid5_release_stripe() while holding conf->device_lock
1386          */
1387         BUG_ON(test_bit(STRIPE_ON_RELEASE_LIST, &sh->state));
1388         lockdep_assert_held(&conf->device_lock);
1389
1390         list_del_init(&sh->lru);
1391         atomic_inc(&sh->count);
1392
1393         set_bit(STRIPE_HANDLE, &sh->state);
1394         atomic_inc(&conf->active_stripes);
1395         r5c_make_stripe_write_out(sh);
1396
1397         if (test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
1398                 atomic_inc(&conf->r5c_flushing_partial_stripes);
1399         else
1400                 atomic_inc(&conf->r5c_flushing_full_stripes);
1401         raid5_release_stripe(sh);
1402 }
1403
1404 /*
1405  * if num == 0, flush all full stripes
1406  * if num > 0, flush all full stripes. If less than num full stripes are
1407  *             flushed, flush some partial stripes until totally num stripes are
1408  *             flushed or there is no more cached stripes.
1409  */
1410 void r5c_flush_cache(struct r5conf *conf, int num)
1411 {
1412         int count;
1413         struct stripe_head *sh, *next;
1414
1415         lockdep_assert_held(&conf->device_lock);
1416         if (!conf->log)
1417                 return;
1418
1419         count = 0;
1420         list_for_each_entry_safe(sh, next, &conf->r5c_full_stripe_list, lru) {
1421                 r5c_flush_stripe(conf, sh);
1422                 count++;
1423         }
1424
1425         if (count >= num)
1426                 return;
1427         list_for_each_entry_safe(sh, next,
1428                                  &conf->r5c_partial_stripe_list, lru) {
1429                 r5c_flush_stripe(conf, sh);
1430                 if (++count >= num)
1431                         break;
1432         }
1433 }
1434
1435 static void r5c_do_reclaim(struct r5conf *conf)
1436 {
1437         struct r5l_log *log = conf->log;
1438         struct stripe_head *sh;
1439         int count = 0;
1440         unsigned long flags;
1441         int total_cached;
1442         int stripes_to_flush;
1443         int flushing_partial, flushing_full;
1444
1445         if (!r5c_is_writeback(log))
1446                 return;
1447
1448         flushing_partial = atomic_read(&conf->r5c_flushing_partial_stripes);
1449         flushing_full = atomic_read(&conf->r5c_flushing_full_stripes);
1450         total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
1451                 atomic_read(&conf->r5c_cached_full_stripes) -
1452                 flushing_full - flushing_partial;
1453
1454         if (total_cached > conf->min_nr_stripes * 3 / 4 ||
1455             atomic_read(&conf->empty_inactive_list_nr) > 0)
1456                 /*
1457                  * if stripe cache pressure high, flush all full stripes and
1458                  * some partial stripes
1459                  */
1460                 stripes_to_flush = R5C_RECLAIM_STRIPE_GROUP;
1461         else if (total_cached > conf->min_nr_stripes * 1 / 2 ||
1462                  atomic_read(&conf->r5c_cached_full_stripes) - flushing_full >
1463                  R5C_FULL_STRIPE_FLUSH_BATCH(conf))
1464                 /*
1465                  * if stripe cache pressure moderate, or if there is many full
1466                  * stripes,flush all full stripes
1467                  */
1468                 stripes_to_flush = 0;
1469         else
1470                 /* no need to flush */
1471                 stripes_to_flush = -1;
1472
1473         if (stripes_to_flush >= 0) {
1474                 spin_lock_irqsave(&conf->device_lock, flags);
1475                 r5c_flush_cache(conf, stripes_to_flush);
1476                 spin_unlock_irqrestore(&conf->device_lock, flags);
1477         }
1478
1479         /* if log space is tight, flush stripes on stripe_in_journal_list */
1480         if (test_bit(R5C_LOG_TIGHT, &conf->cache_state)) {
1481                 spin_lock_irqsave(&log->stripe_in_journal_lock, flags);
1482                 spin_lock(&conf->device_lock);
1483                 list_for_each_entry(sh, &log->stripe_in_journal_list, r5c) {
1484                         /*
1485                          * stripes on stripe_in_journal_list could be in any
1486                          * state of the stripe_cache state machine. In this
1487                          * case, we only want to flush stripe on
1488                          * r5c_cached_full/partial_stripes. The following
1489                          * condition makes sure the stripe is on one of the
1490                          * two lists.
1491                          */
1492                         if (!list_empty(&sh->lru) &&
1493                             !test_bit(STRIPE_HANDLE, &sh->state) &&
1494                             atomic_read(&sh->count) == 0) {
1495                                 r5c_flush_stripe(conf, sh);
1496                                 if (count++ >= R5C_RECLAIM_STRIPE_GROUP)
1497                                         break;
1498                         }
1499                 }
1500                 spin_unlock(&conf->device_lock);
1501                 spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
1502         }
1503
1504         if (!test_bit(R5C_LOG_CRITICAL, &conf->cache_state))
1505                 r5l_run_no_space_stripes(log);
1506
1507         md_wakeup_thread(conf->mddev->thread);
1508 }
1509
1510 static void r5l_do_reclaim(struct r5l_log *log)
1511 {
1512         struct r5conf *conf = log->rdev->mddev->private;
1513         sector_t reclaim_target = xchg(&log->reclaim_target, 0);
1514         sector_t reclaimable;
1515         sector_t next_checkpoint;
1516         bool write_super;
1517
1518         spin_lock_irq(&log->io_list_lock);
1519         write_super = r5l_reclaimable_space(log) > log->max_free_space ||
1520                 reclaim_target != 0 || !list_empty(&log->no_space_stripes);
1521         /*
1522          * move proper io_unit to reclaim list. We should not change the order.
1523          * reclaimable/unreclaimable io_unit can be mixed in the list, we
1524          * shouldn't reuse space of an unreclaimable io_unit
1525          */
1526         while (1) {
1527                 reclaimable = r5l_reclaimable_space(log);
1528                 if (reclaimable >= reclaim_target ||
1529                     (list_empty(&log->running_ios) &&
1530                      list_empty(&log->io_end_ios) &&
1531                      list_empty(&log->flushing_ios) &&
1532                      list_empty(&log->finished_ios)))
1533                         break;
1534
1535                 md_wakeup_thread(log->rdev->mddev->thread);
1536                 wait_event_lock_irq(log->iounit_wait,
1537                                     r5l_reclaimable_space(log) > reclaimable,
1538                                     log->io_list_lock);
1539         }
1540
1541         next_checkpoint = r5c_calculate_new_cp(conf);
1542         spin_unlock_irq(&log->io_list_lock);
1543
1544         if (reclaimable == 0 || !write_super)
1545                 return;
1546
1547         /*
1548          * write_super will flush cache of each raid disk. We must write super
1549          * here, because the log area might be reused soon and we don't want to
1550          * confuse recovery
1551          */
1552         r5l_write_super_and_discard_space(log, next_checkpoint);
1553
1554         mutex_lock(&log->io_mutex);
1555         log->last_checkpoint = next_checkpoint;
1556         r5c_update_log_state(log);
1557         mutex_unlock(&log->io_mutex);
1558
1559         r5l_run_no_space_stripes(log);
1560 }
1561
1562 static void r5l_reclaim_thread(struct md_thread *thread)
1563 {
1564         struct mddev *mddev = thread->mddev;
1565         struct r5conf *conf = mddev->private;
1566         struct r5l_log *log = conf->log;
1567
1568         if (!log)
1569                 return;
1570         r5c_do_reclaim(conf);
1571         r5l_do_reclaim(log);
1572 }
1573
1574 void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
1575 {
1576         unsigned long target;
1577         unsigned long new = (unsigned long)space; /* overflow in theory */
1578
1579         if (!log)
1580                 return;
1581         do {
1582                 target = log->reclaim_target;
1583                 if (new < target)
1584                         return;
1585         } while (cmpxchg(&log->reclaim_target, target, new) != target);
1586         md_wakeup_thread(log->reclaim_thread);
1587 }
1588
1589 void r5l_quiesce(struct r5l_log *log, int quiesce)
1590 {
1591         struct mddev *mddev;
1592
1593         if (quiesce) {
1594                 /* make sure r5l_write_super_and_discard_space exits */
1595                 mddev = log->rdev->mddev;
1596                 wake_up(&mddev->sb_wait);
1597                 kthread_park(log->reclaim_thread->tsk);
1598                 r5l_wake_reclaim(log, MaxSector);
1599                 r5l_do_reclaim(log);
1600         } else
1601                 kthread_unpark(log->reclaim_thread->tsk);
1602 }
1603
1604 bool r5l_log_disk_error(struct r5conf *conf)
1605 {
1606         struct r5l_log *log;
1607         bool ret;
1608         /* don't allow write if journal disk is missing */
1609         rcu_read_lock();
1610         log = rcu_dereference(conf->log);
1611
1612         if (!log)
1613                 ret = test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
1614         else
1615                 ret = test_bit(Faulty, &log->rdev->flags);
1616         rcu_read_unlock();
1617         return ret;
1618 }
1619
1620 #define R5L_RECOVERY_PAGE_POOL_SIZE 256
1621
1622 struct r5l_recovery_ctx {
1623         struct page *meta_page;         /* current meta */
1624         sector_t meta_total_blocks;     /* total size of current meta and data */
1625         sector_t pos;                   /* recovery position */
1626         u64 seq;                        /* recovery position seq */
1627         int data_parity_stripes;        /* number of data_parity stripes */
1628         int data_only_stripes;          /* number of data_only stripes */
1629         struct list_head cached_list;
1630
1631         /*
1632          * read ahead page pool (ra_pool)
1633          * in recovery, log is read sequentially. It is not efficient to
1634          * read every page with sync_page_io(). The read ahead page pool
1635          * reads multiple pages with one IO, so further log read can
1636          * just copy data from the pool.
1637          */
1638         struct page *ra_pool[R5L_RECOVERY_PAGE_POOL_SIZE];
1639         sector_t pool_offset;   /* offset of first page in the pool */
1640         int total_pages;        /* total allocated pages */
1641         int valid_pages;        /* pages with valid data */
1642         struct bio *ra_bio;     /* bio to do the read ahead */
1643 };
1644
1645 static int r5l_recovery_allocate_ra_pool(struct r5l_log *log,
1646                                             struct r5l_recovery_ctx *ctx)
1647 {
1648         struct page *page;
1649
1650         ctx->ra_bio = bio_alloc_bioset(GFP_KERNEL, BIO_MAX_PAGES, log->bs);
1651         if (!ctx->ra_bio)
1652                 return -ENOMEM;
1653
1654         ctx->valid_pages = 0;
1655         ctx->total_pages = 0;
1656         while (ctx->total_pages < R5L_RECOVERY_PAGE_POOL_SIZE) {
1657                 page = alloc_page(GFP_KERNEL);
1658
1659                 if (!page)
1660                         break;
1661                 ctx->ra_pool[ctx->total_pages] = page;
1662                 ctx->total_pages += 1;
1663         }
1664
1665         if (ctx->total_pages == 0) {
1666                 bio_put(ctx->ra_bio);
1667                 return -ENOMEM;
1668         }
1669
1670         ctx->pool_offset = 0;
1671         return 0;
1672 }
1673
1674 static void r5l_recovery_free_ra_pool(struct r5l_log *log,
1675                                         struct r5l_recovery_ctx *ctx)
1676 {
1677         int i;
1678
1679         for (i = 0; i < ctx->total_pages; ++i)
1680                 put_page(ctx->ra_pool[i]);
1681         bio_put(ctx->ra_bio);
1682 }
1683
1684 /*
1685  * fetch ctx->valid_pages pages from offset
1686  * In normal cases, ctx->valid_pages == ctx->total_pages after the call.
1687  * However, if the offset is close to the end of the journal device,
1688  * ctx->valid_pages could be smaller than ctx->total_pages
1689  */
1690 static int r5l_recovery_fetch_ra_pool(struct r5l_log *log,
1691                                       struct r5l_recovery_ctx *ctx,
1692                                       sector_t offset)
1693 {
1694         bio_reset(ctx->ra_bio);
1695         bio_set_dev(ctx->ra_bio, log->rdev->bdev);
1696         bio_set_op_attrs(ctx->ra_bio, REQ_OP_READ, 0);
1697         ctx->ra_bio->bi_iter.bi_sector = log->rdev->data_offset + offset;
1698
1699         ctx->valid_pages = 0;
1700         ctx->pool_offset = offset;
1701
1702         while (ctx->valid_pages < ctx->total_pages) {
1703                 bio_add_page(ctx->ra_bio,
1704                              ctx->ra_pool[ctx->valid_pages], PAGE_SIZE, 0);
1705                 ctx->valid_pages += 1;
1706
1707                 offset = r5l_ring_add(log, offset, BLOCK_SECTORS);
1708
1709                 if (offset == 0)  /* reached end of the device */
1710                         break;
1711         }
1712
1713         return submit_bio_wait(ctx->ra_bio);
1714 }
1715
1716 /*
1717  * try read a page from the read ahead page pool, if the page is not in the
1718  * pool, call r5l_recovery_fetch_ra_pool
1719  */
1720 static int r5l_recovery_read_page(struct r5l_log *log,
1721                                   struct r5l_recovery_ctx *ctx,
1722                                   struct page *page,
1723                                   sector_t offset)
1724 {
1725         int ret;
1726
1727         if (offset < ctx->pool_offset ||
1728             offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS) {
1729                 ret = r5l_recovery_fetch_ra_pool(log, ctx, offset);
1730                 if (ret)
1731                         return ret;
1732         }
1733
1734         BUG_ON(offset < ctx->pool_offset ||
1735                offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS);
1736
1737         memcpy(page_address(page),
1738                page_address(ctx->ra_pool[(offset - ctx->pool_offset) >>
1739                                          BLOCK_SECTOR_SHIFT]),
1740                PAGE_SIZE);
1741         return 0;
1742 }
1743
1744 static int r5l_recovery_read_meta_block(struct r5l_log *log,
1745                                         struct r5l_recovery_ctx *ctx)
1746 {
1747         struct page *page = ctx->meta_page;
1748         struct r5l_meta_block *mb;
1749         u32 crc, stored_crc;
1750         int ret;
1751
1752         ret = r5l_recovery_read_page(log, ctx, page, ctx->pos);
1753         if (ret != 0)
1754                 return ret;
1755
1756         mb = page_address(page);
1757         stored_crc = le32_to_cpu(mb->checksum);
1758         mb->checksum = 0;
1759
1760         if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
1761             le64_to_cpu(mb->seq) != ctx->seq ||
1762             mb->version != R5LOG_VERSION ||
1763             le64_to_cpu(mb->position) != ctx->pos)
1764                 return -EINVAL;
1765
1766         crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
1767         if (stored_crc != crc)
1768                 return -EINVAL;
1769
1770         if (le32_to_cpu(mb->meta_size) > PAGE_SIZE)
1771                 return -EINVAL;
1772
1773         ctx->meta_total_blocks = BLOCK_SECTORS;
1774
1775         return 0;
1776 }
1777
1778 static void
1779 r5l_recovery_create_empty_meta_block(struct r5l_log *log,
1780                                      struct page *page,
1781                                      sector_t pos, u64 seq)
1782 {
1783         struct r5l_meta_block *mb;
1784
1785         mb = page_address(page);
1786         clear_page(mb);
1787         mb->magic = cpu_to_le32(R5LOG_MAGIC);
1788         mb->version = R5LOG_VERSION;
1789         mb->meta_size = cpu_to_le32(sizeof(struct r5l_meta_block));
1790         mb->seq = cpu_to_le64(seq);
1791         mb->position = cpu_to_le64(pos);
1792 }
1793
1794 static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
1795                                           u64 seq)
1796 {
1797         struct page *page;
1798         struct r5l_meta_block *mb;
1799
1800         page = alloc_page(GFP_KERNEL);
1801         if (!page)
1802                 return -ENOMEM;
1803         r5l_recovery_create_empty_meta_block(log, page, pos, seq);
1804         mb = page_address(page);
1805         mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
1806                                              mb, PAGE_SIZE));
1807         if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, REQ_OP_WRITE,
1808                           REQ_SYNC | REQ_FUA, false)) {
1809                 __free_page(page);
1810                 return -EIO;
1811         }
1812         __free_page(page);
1813         return 0;
1814 }
1815
1816 /*
1817  * r5l_recovery_load_data and r5l_recovery_load_parity uses flag R5_Wantwrite
1818  * to mark valid (potentially not flushed) data in the journal.
1819  *
1820  * We already verified checksum in r5l_recovery_verify_data_checksum_for_mb,
1821  * so there should not be any mismatch here.
1822  */
1823 static void r5l_recovery_load_data(struct r5l_log *log,
1824                                    struct stripe_head *sh,
1825                                    struct r5l_recovery_ctx *ctx,
1826                                    struct r5l_payload_data_parity *payload,
1827                                    sector_t log_offset)
1828 {
1829         struct mddev *mddev = log->rdev->mddev;
1830         struct r5conf *conf = mddev->private;
1831         int dd_idx;
1832
1833         raid5_compute_sector(conf,
1834                              le64_to_cpu(payload->location), 0,
1835                              &dd_idx, sh);
1836         r5l_recovery_read_page(log, ctx, sh->dev[dd_idx].page, log_offset);
1837         sh->dev[dd_idx].log_checksum =
1838                 le32_to_cpu(payload->checksum[0]);
1839         ctx->meta_total_blocks += BLOCK_SECTORS;
1840
1841         set_bit(R5_Wantwrite, &sh->dev[dd_idx].flags);
1842         set_bit(STRIPE_R5C_CACHING, &sh->state);
1843 }
1844
1845 static void r5l_recovery_load_parity(struct r5l_log *log,
1846                                      struct stripe_head *sh,
1847                                      struct r5l_recovery_ctx *ctx,
1848                                      struct r5l_payload_data_parity *payload,
1849                                      sector_t log_offset)
1850 {
1851         struct mddev *mddev = log->rdev->mddev;
1852         struct r5conf *conf = mddev->private;
1853
1854         ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded;
1855         r5l_recovery_read_page(log, ctx, sh->dev[sh->pd_idx].page, log_offset);
1856         sh->dev[sh->pd_idx].log_checksum =
1857                 le32_to_cpu(payload->checksum[0]);
1858         set_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags);
1859
1860         if (sh->qd_idx >= 0) {
1861                 r5l_recovery_read_page(
1862                         log, ctx, sh->dev[sh->qd_idx].page,
1863                         r5l_ring_add(log, log_offset, BLOCK_SECTORS));
1864                 sh->dev[sh->qd_idx].log_checksum =
1865                         le32_to_cpu(payload->checksum[1]);
1866                 set_bit(R5_Wantwrite, &sh->dev[sh->qd_idx].flags);
1867         }
1868         clear_bit(STRIPE_R5C_CACHING, &sh->state);
1869 }
1870
1871 static void r5l_recovery_reset_stripe(struct stripe_head *sh)
1872 {
1873         int i;
1874
1875         sh->state = 0;
1876         sh->log_start = MaxSector;
1877         for (i = sh->disks; i--; )
1878                 sh->dev[i].flags = 0;
1879 }
1880
1881 static void
1882 r5l_recovery_replay_one_stripe(struct r5conf *conf,
1883                                struct stripe_head *sh,
1884                                struct r5l_recovery_ctx *ctx)
1885 {
1886         struct md_rdev *rdev, *rrdev;
1887         int disk_index;
1888         int data_count = 0;
1889
1890         for (disk_index = 0; disk_index < sh->disks; disk_index++) {
1891                 if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
1892                         continue;
1893                 if (disk_index == sh->qd_idx || disk_index == sh->pd_idx)
1894                         continue;
1895                 data_count++;
1896         }
1897
1898         /*
1899          * stripes that only have parity must have been flushed
1900          * before the crash that we are now recovering from, so
1901          * there is nothing more to recovery.
1902          */
1903         if (data_count == 0)
1904                 goto out;
1905
1906         for (disk_index = 0; disk_index < sh->disks; disk_index++) {
1907                 if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
1908                         continue;
1909
1910                 /* in case device is broken */
1911                 rcu_read_lock();
1912                 rdev = rcu_dereference(conf->disks[disk_index].rdev);
1913                 if (rdev) {
1914                         atomic_inc(&rdev->nr_pending);
1915                         rcu_read_unlock();
1916                         sync_page_io(rdev, sh->sector, PAGE_SIZE,
1917                                      sh->dev[disk_index].page, REQ_OP_WRITE, 0,
1918                                      false);
1919                         rdev_dec_pending(rdev, rdev->mddev);
1920                         rcu_read_lock();
1921                 }
1922                 rrdev = rcu_dereference(conf->disks[disk_index].replacement);
1923                 if (rrdev) {
1924                         atomic_inc(&rrdev->nr_pending);
1925                         rcu_read_unlock();
1926                         sync_page_io(rrdev, sh->sector, PAGE_SIZE,
1927                                      sh->dev[disk_index].page, REQ_OP_WRITE, 0,
1928                                      false);
1929                         rdev_dec_pending(rrdev, rrdev->mddev);
1930                         rcu_read_lock();
1931                 }
1932                 rcu_read_unlock();
1933         }
1934         ctx->data_parity_stripes++;
1935 out:
1936         r5l_recovery_reset_stripe(sh);
1937 }
1938
1939 static struct stripe_head *
1940 r5c_recovery_alloc_stripe(struct r5conf *conf,
1941                           sector_t stripe_sect)
1942 {
1943         struct stripe_head *sh;
1944
1945         sh = raid5_get_active_stripe(conf, stripe_sect, 0, 1, 0);
1946         if (!sh)
1947                 return NULL;  /* no more stripe available */
1948
1949         r5l_recovery_reset_stripe(sh);
1950
1951         return sh;
1952 }
1953
1954 static struct stripe_head *
1955 r5c_recovery_lookup_stripe(struct list_head *list, sector_t sect)
1956 {
1957         struct stripe_head *sh;
1958
1959         list_for_each_entry(sh, list, lru)
1960                 if (sh->sector == sect)
1961                         return sh;
1962         return NULL;
1963 }
1964
1965 static void
1966 r5c_recovery_drop_stripes(struct list_head *cached_stripe_list,
1967                           struct r5l_recovery_ctx *ctx)
1968 {
1969         struct stripe_head *sh, *next;
1970
1971         list_for_each_entry_safe(sh, next, cached_stripe_list, lru) {
1972                 r5l_recovery_reset_stripe(sh);
1973                 list_del_init(&sh->lru);
1974                 raid5_release_stripe(sh);
1975         }
1976 }
1977
1978 static void
1979 r5c_recovery_replay_stripes(struct list_head *cached_stripe_list,
1980                             struct r5l_recovery_ctx *ctx)
1981 {
1982         struct stripe_head *sh, *next;
1983
1984         list_for_each_entry_safe(sh, next, cached_stripe_list, lru)
1985                 if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
1986                         r5l_recovery_replay_one_stripe(sh->raid_conf, sh, ctx);
1987                         list_del_init(&sh->lru);
1988                         raid5_release_stripe(sh);
1989                 }
1990 }
1991
1992 /* if matches return 0; otherwise return -EINVAL */
1993 static int
1994 r5l_recovery_verify_data_checksum(struct r5l_log *log,
1995                                   struct r5l_recovery_ctx *ctx,
1996                                   struct page *page,
1997                                   sector_t log_offset, __le32 log_checksum)
1998 {
1999         void *addr;
2000         u32 checksum;
2001
2002         r5l_recovery_read_page(log, ctx, page, log_offset);
2003         addr = kmap_atomic(page);
2004         checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
2005         kunmap_atomic(addr);
2006         return (le32_to_cpu(log_checksum) == checksum) ? 0 : -EINVAL;
2007 }
2008
2009 /*
2010  * before loading data to stripe cache, we need verify checksum for all data,
2011  * if there is mismatch for any data page, we drop all data in the mata block
2012  */
2013 static int
2014 r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log,
2015                                          struct r5l_recovery_ctx *ctx)
2016 {
2017         struct mddev *mddev = log->rdev->mddev;
2018         struct r5conf *conf = mddev->private;
2019         struct r5l_meta_block *mb = page_address(ctx->meta_page);
2020         sector_t mb_offset = sizeof(struct r5l_meta_block);
2021         sector_t log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
2022         struct page *page;
2023         struct r5l_payload_data_parity *payload;
2024         struct r5l_payload_flush *payload_flush;
2025
2026         page = alloc_page(GFP_KERNEL);
2027         if (!page)
2028                 return -ENOMEM;
2029
2030         while (mb_offset < le32_to_cpu(mb->meta_size)) {
2031                 payload = (void *)mb + mb_offset;
2032                 payload_flush = (void *)mb + mb_offset;
2033
2034                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) {
2035                         if (r5l_recovery_verify_data_checksum(
2036                                     log, ctx, page, log_offset,
2037                                     payload->checksum[0]) < 0)
2038                                 goto mismatch;
2039                 } else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_PARITY) {
2040                         if (r5l_recovery_verify_data_checksum(
2041                                     log, ctx, page, log_offset,
2042                                     payload->checksum[0]) < 0)
2043                                 goto mismatch;
2044                         if (conf->max_degraded == 2 && /* q for RAID 6 */
2045                             r5l_recovery_verify_data_checksum(
2046                                     log, ctx, page,
2047                                     r5l_ring_add(log, log_offset,
2048                                                  BLOCK_SECTORS),
2049                                     payload->checksum[1]) < 0)
2050                                 goto mismatch;
2051                 } else if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
2052                         /* nothing to do for R5LOG_PAYLOAD_FLUSH here */
2053                 } else /* not R5LOG_PAYLOAD_DATA/PARITY/FLUSH */
2054                         goto mismatch;
2055
2056                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
2057                         mb_offset += sizeof(struct r5l_payload_flush) +
2058                                 le32_to_cpu(payload_flush->size);
2059                 } else {
2060                         /* DATA or PARITY payload */
2061                         log_offset = r5l_ring_add(log, log_offset,
2062                                                   le32_to_cpu(payload->size));
2063                         mb_offset += sizeof(struct r5l_payload_data_parity) +
2064                                 sizeof(__le32) *
2065                                 (le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
2066                 }
2067
2068         }
2069
2070         put_page(page);
2071         return 0;
2072
2073 mismatch:
2074         put_page(page);
2075         return -EINVAL;
2076 }
2077
2078 /*
2079  * Analyze all data/parity pages in one meta block
2080  * Returns:
2081  * 0 for success
2082  * -EINVAL for unknown playload type
2083  * -EAGAIN for checksum mismatch of data page
2084  * -ENOMEM for run out of memory (alloc_page failed or run out of stripes)
2085  */
2086 static int
2087 r5c_recovery_analyze_meta_block(struct r5l_log *log,
2088                                 struct r5l_recovery_ctx *ctx,
2089                                 struct list_head *cached_stripe_list)
2090 {
2091         struct mddev *mddev = log->rdev->mddev;
2092         struct r5conf *conf = mddev->private;
2093         struct r5l_meta_block *mb;
2094         struct r5l_payload_data_parity *payload;
2095         struct r5l_payload_flush *payload_flush;
2096         int mb_offset;
2097         sector_t log_offset;
2098         sector_t stripe_sect;
2099         struct stripe_head *sh;
2100         int ret;
2101
2102         /*
2103          * for mismatch in data blocks, we will drop all data in this mb, but
2104          * we will still read next mb for other data with FLUSH flag, as
2105          * io_unit could finish out of order.
2106          */
2107         ret = r5l_recovery_verify_data_checksum_for_mb(log, ctx);
2108         if (ret == -EINVAL)
2109                 return -EAGAIN;
2110         else if (ret)
2111                 return ret;   /* -ENOMEM duo to alloc_page() failed */
2112
2113         mb = page_address(ctx->meta_page);
2114         mb_offset = sizeof(struct r5l_meta_block);
2115         log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
2116
2117         while (mb_offset < le32_to_cpu(mb->meta_size)) {
2118                 int dd;
2119
2120                 payload = (void *)mb + mb_offset;
2121                 payload_flush = (void *)mb + mb_offset;
2122
2123                 if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_FLUSH) {
2124                         int i, count;
2125
2126                         count = le32_to_cpu(payload_flush->size) / sizeof(__le64);
2127                         for (i = 0; i < count; ++i) {
2128                                 stripe_sect = le64_to_cpu(payload_flush->flush_stripes[i]);
2129                                 sh = r5c_recovery_lookup_stripe(cached_stripe_list,
2130                                                                 stripe_sect);
2131                                 if (sh) {
2132                                         WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
2133                                         r5l_recovery_reset_stripe(sh);
2134                                         list_del_init(&sh->lru);
2135                                         raid5_release_stripe(sh);
2136                                 }
2137                         }
2138
2139                         mb_offset += sizeof(struct r5l_payload_flush) +
2140                                 le32_to_cpu(payload_flush->size);
2141                         continue;
2142                 }
2143
2144                 /* DATA or PARITY payload */
2145                 stripe_sect = (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) ?
2146                         raid5_compute_sector(
2147                                 conf, le64_to_cpu(payload->location), 0, &dd,
2148                                 NULL)
2149                         : le64_to_cpu(payload->location);
2150
2151                 sh = r5c_recovery_lookup_stripe(cached_stripe_list,
2152                                                 stripe_sect);
2153
2154                 if (!sh) {
2155                         sh = r5c_recovery_alloc_stripe(conf, stripe_sect);
2156                         /*
2157                          * cannot get stripe from raid5_get_active_stripe
2158                          * try replay some stripes
2159                          */
2160                         if (!sh) {
2161                                 r5c_recovery_replay_stripes(
2162                                         cached_stripe_list, ctx);
2163                                 sh = r5c_recovery_alloc_stripe(
2164                                         conf, stripe_sect);
2165                         }
2166                         if (!sh) {
2167                                 pr_debug("md/raid:%s: Increasing stripe cache size to %d to recovery data on journal.\n",
2168                                         mdname(mddev),
2169                                         conf->min_nr_stripes * 2);
2170                                 raid5_set_cache_size(mddev,
2171                                                      conf->min_nr_stripes * 2);
2172                                 sh = r5c_recovery_alloc_stripe(conf,
2173                                                                stripe_sect);
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
3070         pr_debug("md/raid:%s: using device %s as journal\n",
3071                  mdname(conf->mddev), bdevname(rdev->bdev, b));
3072
3073         if (PAGE_SIZE != 4096)
3074                 return -EINVAL;
3075
3076         /*
3077          * The PAGE_SIZE must be big enough to hold 1 r5l_meta_block and
3078          * raid_disks r5l_payload_data_parity.
3079          *
3080          * Write journal and cache does not work for very big array
3081          * (raid_disks > 203)
3082          */
3083         if (sizeof(struct r5l_meta_block) +
3084             ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32)) *
3085              conf->raid_disks) > PAGE_SIZE) {
3086                 pr_err("md/raid:%s: write journal/cache doesn't work for array with %d disks\n",
3087                        mdname(conf->mddev), conf->raid_disks);
3088                 return -EINVAL;
3089         }
3090
3091         log = kzalloc(sizeof(*log), GFP_KERNEL);
3092         if (!log)
3093                 return -ENOMEM;
3094         log->rdev = rdev;
3095
3096         log->need_cache_flush = test_bit(QUEUE_FLAG_WC, &q->queue_flags) != 0;
3097
3098         log->uuid_checksum = crc32c_le(~0, rdev->mddev->uuid,
3099                                        sizeof(rdev->mddev->uuid));
3100
3101         mutex_init(&log->io_mutex);
3102
3103         spin_lock_init(&log->io_list_lock);
3104         INIT_LIST_HEAD(&log->running_ios);
3105         INIT_LIST_HEAD(&log->io_end_ios);
3106         INIT_LIST_HEAD(&log->flushing_ios);
3107         INIT_LIST_HEAD(&log->finished_ios);
3108         bio_init(&log->flush_bio, NULL, 0);
3109
3110         log->io_kc = KMEM_CACHE(r5l_io_unit, 0);
3111         if (!log->io_kc)
3112                 goto io_kc;
3113
3114         log->io_pool = mempool_create_slab_pool(R5L_POOL_SIZE, log->io_kc);
3115         if (!log->io_pool)
3116                 goto io_pool;
3117
3118         log->bs = bioset_create(R5L_POOL_SIZE, 0, BIOSET_NEED_BVECS);
3119         if (!log->bs)
3120                 goto io_bs;
3121
3122         log->meta_pool = mempool_create_page_pool(R5L_POOL_SIZE, 0);
3123         if (!log->meta_pool)
3124                 goto out_mempool;
3125
3126         spin_lock_init(&log->tree_lock);
3127         INIT_RADIX_TREE(&log->big_stripe_tree, GFP_NOWAIT | __GFP_NOWARN);
3128
3129         log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
3130                                                  log->rdev->mddev, "reclaim");
3131         if (!log->reclaim_thread)
3132                 goto reclaim_thread;
3133         log->reclaim_thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;
3134
3135         init_waitqueue_head(&log->iounit_wait);
3136
3137         INIT_LIST_HEAD(&log->no_mem_stripes);
3138
3139         INIT_LIST_HEAD(&log->no_space_stripes);
3140         spin_lock_init(&log->no_space_stripes_lock);
3141
3142         INIT_WORK(&log->deferred_io_work, r5l_submit_io_async);
3143         INIT_WORK(&log->disable_writeback_work, r5c_disable_writeback_async);
3144
3145         log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
3146         INIT_LIST_HEAD(&log->stripe_in_journal_list);
3147         spin_lock_init(&log->stripe_in_journal_lock);
3148         atomic_set(&log->stripe_in_journal_count, 0);
3149
3150         rcu_assign_pointer(conf->log, log);
3151
3152         set_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
3153         return 0;
3154
3155         rcu_assign_pointer(conf->log, NULL);
3156         md_unregister_thread(&log->reclaim_thread);
3157 reclaim_thread:
3158         mempool_destroy(log->meta_pool);
3159 out_mempool:
3160         bioset_free(log->bs);
3161 io_bs:
3162         mempool_destroy(log->io_pool);
3163 io_pool:
3164         kmem_cache_destroy(log->io_kc);
3165 io_kc:
3166         kfree(log);
3167         return -EINVAL;
3168 }
3169
3170 void r5l_exit_log(struct r5conf *conf)
3171 {
3172         struct r5l_log *log = conf->log;
3173
3174         conf->log = NULL;
3175         synchronize_rcu();
3176
3177         /* Ensure disable_writeback_work wakes up and exits */
3178         wake_up(&conf->mddev->sb_wait);
3179         flush_work(&log->disable_writeback_work);
3180         md_unregister_thread(&log->reclaim_thread);
3181         mempool_destroy(log->meta_pool);
3182         bioset_free(log->bs);
3183         mempool_destroy(log->io_pool);
3184         kmem_cache_destroy(log->io_kc);
3185         kfree(log);