1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _RAID5_H
3#define _RAID5_H
4
5#include <linux/raid/xor.h>
6#include <linux/dmaengine.h>
7
8/*
9 *
10 * Each stripe contains one buffer per device. Each buffer can be in
11 * one of a number of states stored in "flags". Changes between
12 * these states happen *almost* exclusively under the protection of the
13 * STRIPE_ACTIVE flag. Some very specific changes can happen in bi_end_io, and
14 * these are not protected by STRIPE_ACTIVE.
15 *
16 * The flag bits that are used to represent these states are:
17 * R5_UPTODATE and R5_LOCKED
18 *
19 * State Empty == !UPTODATE, !LOCK
20 * We have no data, and there is no active request
21 * State Want == !UPTODATE, LOCK
22 * A read request is being submitted for this block
23 * State Dirty == UPTODATE, LOCK
24 * Some new data is in this buffer, and it is being written out
25 * State Clean == UPTODATE, !LOCK
26 * We have valid data which is the same as on disc
27 *
28 * The possible state transitions are:
29 *
30 * Empty -> Want - on read or write to get old data for parity calc
31 * Empty -> Dirty - on compute_parity to satisfy write/sync request.
32 * Empty -> Clean - on compute_block when computing a block for failed drive
33 * Want -> Empty - on failed read
34 * Want -> Clean - on successful completion of read request
35 * Dirty -> Clean - on successful completion of write request
36 * Dirty -> Clean - on failed write
37 * Clean -> Dirty - on compute_parity to satisfy write/sync (RECONSTRUCT or RMW)
38 *
39 * The Want->Empty, Want->Clean, Dirty->Clean, transitions
40 * all happen in b_end_io at interrupt time.
41 * Each sets the Uptodate bit before releasing the Lock bit.
42 * This leaves one multi-stage transition:
43 * Want->Dirty->Clean
44 * This is safe because thinking that a Clean buffer is actually dirty
45 * will at worst delay some action, and the stripe will be scheduled
46 * for attention after the transition is complete.
47 *
48 * There is one possibility that is not covered by these states. That
49 * is if one drive has failed and there is a spare being rebuilt. We
50 * can't distinguish between a clean block that has been generated
51 * from parity calculations, and a clean block that has been
52 * successfully written to the spare ( or to parity when resyncing).
53 * To distinguish these states we have a stripe bit STRIPE_INSYNC that
54 * is set whenever a write is scheduled to the spare, or to the parity
55 * disc if there is no spare. A sync request clears this bit, and
56 * when we find it set with no buffers locked, we know the sync is
57 * complete.
58 *
59 * Buffers for the md device that arrive via make_request are attached
60 * to the appropriate stripe in one of two lists linked on b_reqnext.
61 * One list (bh_read) for read requests, one (bh_write) for write.
62 * There should never be more than one buffer on the two lists
63 * together, but we are not guaranteed of that so we allow for more.
64 *
65 * If a buffer is on the read list when the associated cache buffer is
66 * Uptodate, the data is copied into the read buffer and it's b_end_io
67 * routine is called. This may happen in the end_request routine only
68 * if the buffer has just successfully been read. end_request should
69 * remove the buffers from the list and then set the Uptodate bit on
70 * the buffer. Other threads may do this only if they first check
71 * that the Uptodate bit is set. Once they have checked that they may
72 * take buffers off the read queue.
73 *
74 * When a buffer on the write list is committed for write it is copied
75 * into the cache buffer, which is then marked dirty, and moved onto a
76 * third list, the written list (bh_written). Once both the parity
77 * block and the cached buffer are successfully written, any buffer on
78 * a written list can be returned with b_end_io.
79 *
80 * The write list and read list both act as fifos. The read list,
81 * write list and written list are protected by the device_lock.
82 * The device_lock is only for list manipulations and will only be
83 * held for a very short time. It can be claimed from interrupts.
84 *
85 *
86 * Stripes in the stripe cache can be on one of two lists (or on
87 * neither). The "inactive_list" contains stripes which are not
88 * currently being used for any request. They can freely be reused
89 * for another stripe. The "handle_list" contains stripes that need
90 * to be handled in some way. Both of these are fifo queues. Each
91 * stripe is also (potentially) linked to a hash bucket in the hash
92 * table so that it can be found by sector number. Stripes that are
93 * not hashed must be on the inactive_list, and will normally be at
94 * the front. All stripes start life this way.
95 *
96 * The inactive_list, handle_list and hash bucket lists are all protected by the
97 * device_lock.
98 * - stripes have a reference counter. If count==0, they are on a list.
99 * - If a stripe might need handling, STRIPE_HANDLE is set.
100 * - When refcount reaches zero, then if STRIPE_HANDLE it is put on
101 * handle_list else inactive_list
102 *
103 * This, combined with the fact that STRIPE_HANDLE is only ever
104 * cleared while a stripe has a non-zero count means that if the
105 * refcount is 0 and STRIPE_HANDLE is set, then it is on the
106 * handle_list and if recount is 0 and STRIPE_HANDLE is not set, then
107 * the stripe is on inactive_list.
108 *
109 * The possible transitions are:
110 * activate an unhashed/inactive stripe (get_active_stripe())
111 * lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev
112 * activate a hashed, possibly active stripe (get_active_stripe())
113 * lockdev check-hash if(!cnt++)unlink-stripe unlockdev
114 * attach a request to an active stripe (add_stripe_bh())
115 * lockdev attach-buffer unlockdev
116 * handle a stripe (handle_stripe())
117 * setSTRIPE_ACTIVE, clrSTRIPE_HANDLE ...
118 * (lockdev check-buffers unlockdev) ..
119 * change-state ..
120 * record io/ops needed clearSTRIPE_ACTIVE schedule io/ops
121 * release an active stripe (release_stripe())
122 * lockdev if (!--cnt) { if STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev
123 *
124 * The refcount counts each thread that have activated the stripe,
125 * plus raid5d if it is handling it, plus one for each active request
126 * on a cached buffer, and plus one if the stripe is undergoing stripe
127 * operations.
128 *
129 * The stripe operations are:
130 * -copying data between the stripe cache and user application buffers
131 * -computing blocks to save a disk access, or to recover a missing block
132 * -updating the parity on a write operation (reconstruct write and
133 * read-modify-write)
134 * -checking parity correctness
135 * -running i/o to disk
136 * These operations are carried out by raid5_run_ops which uses the async_tx
137 * api to (optionally) offload operations to dedicated hardware engines.
138 * When requesting an operation handle_stripe sets the pending bit for the
139 * operation and increments the count. raid5_run_ops is then run whenever
140 * the count is non-zero.
141 * There are some critical dependencies between the operations that prevent some
142 * from being requested while another is in flight.
143 * 1/ Parity check operations destroy the in cache version of the parity block,
144 * so we prevent parity dependent operations like writes and compute_blocks
145 * from starting while a check is in progress. Some dma engines can perform
146 * the check without damaging the parity block, in these cases the parity
147 * block is re-marked up to date (assuming the check was successful) and is
148 * not re-read from disk.
149 * 2/ When a write operation is requested we immediately lock the affected
150 * blocks, and mark them as not up to date. This causes new read requests
151 * to be held off, as well as parity checks and compute block operations.
152 * 3/ Once a compute block operation has been requested handle_stripe treats
153 * that block as if it is up to date. raid5_run_ops guaruntees that any
154 * operation that is dependent on the compute block result is initiated after
155 * the compute block completes.
156 */
157
158/*
159 * Operations state - intermediate states that are visible outside of
160 * STRIPE_ACTIVE.
161 * In general _idle indicates nothing is running, _run indicates a data
162 * processing operation is active, and _result means the data processing result
163 * is stable and can be acted upon. For simple operations like biofill and
164 * compute that only have an _idle and _run state they are indicated with
165 * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN)
166 */
167/**
168 * enum check_states - handles syncing / repairing a stripe
169 * @check_state_idle - check operations are quiesced
170 * @check_state_run - check operation is running
171 * @check_state_result - set outside lock when check result is valid
172 * @check_state_compute_run - check failed and we are repairing
173 * @check_state_compute_result - set outside lock when compute result is valid
174 */
175enum check_states {
176 check_state_idle = 0,
177 check_state_run, /* xor parity check */
178 check_state_run_q, /* q-parity check */
179 check_state_run_pq, /* pq dual parity check */
180 check_state_check_result,
181 check_state_compute_run, /* parity repair */
182 check_state_compute_result,
183};
184
185/**
186 * enum reconstruct_states - handles writing or expanding a stripe
187 */
188enum reconstruct_states {
189 reconstruct_state_idle = 0,
190 reconstruct_state_prexor_drain_run, /* prexor-write */
191 reconstruct_state_drain_run, /* write */
192 reconstruct_state_run, /* expand */
193 reconstruct_state_prexor_drain_result,
194 reconstruct_state_drain_result,
195 reconstruct_state_result,
196};
197
198struct stripe_head {
199 struct hlist_node hash;
200 struct list_head lru; /* inactive_list or handle_list */
201 struct llist_node release_list;
202 struct r5conf *raid_conf;
203 short generation; /* increments with every
204 * reshape */
205 sector_t sector; /* sector of this row */
206 short pd_idx; /* parity disk index */
207 short qd_idx; /* 'Q' disk index for raid6 */
208 short ddf_layout;/* use DDF ordering to calculate Q */
209 short hash_lock_index;
210 unsigned long state; /* state flags */
211 atomic_t count; /* nr of active thread/requests */
212 int bm_seq; /* sequence number for bitmap flushes */
213 int disks; /* disks in stripe */
214 int overwrite_disks; /* total overwrite disks in stripe,
215 * this is only checked when stripe
216 * has STRIPE_BATCH_READY
217 */
218 enum check_states check_state;
219 enum reconstruct_states reconstruct_state;
220 spinlock_t stripe_lock;
221 int cpu;
222 struct r5worker_group *group;
223
224 struct stripe_head *batch_head; /* protected by stripe lock */
225 spinlock_t batch_lock; /* only header's lock is useful */
226 struct list_head batch_list; /* protected by head's batch lock*/
227
228 union {
229 struct r5l_io_unit *log_io;
230 struct ppl_io_unit *ppl_io;
231 };
232
233 struct list_head log_list;
234 sector_t log_start; /* first meta block on the journal */
235 struct list_head r5c; /* for r5c_cache->stripe_in_journal */
236
237 struct page *ppl_page; /* partial parity of this stripe */
238 /**
239 * struct stripe_operations
240 * @target - STRIPE_OP_COMPUTE_BLK target
241 * @target2 - 2nd compute target in the raid6 case
242 * @zero_sum_result - P and Q verification flags
243 * @request - async service request flags for raid_run_ops
244 */
245 struct stripe_operations {
246 int target, target2;
247 enum sum_check_flags zero_sum_result;
248 } ops;
249 struct r5dev {
250 /* rreq and rvec are used for the replacement device when
251 * writing data to both devices.
252 */
253 struct bio req, rreq;
254 struct bio_vec vec, rvec;
255 struct page *page, *orig_page;
256 struct bio *toread, *read, *towrite, *written;
257 sector_t sector; /* sector of this page */
258 unsigned long flags;
259 u32 log_checksum;
260 unsigned short write_hint;
261 } dev[1]; /* allocated with extra space depending of RAID geometry */
262};
263
264/* stripe_head_state - collects and tracks the dynamic state of a stripe_head
265 * for handle_stripe.
266 */
267struct stripe_head_state {
268 /* 'syncing' means that we need to read all devices, either
269 * to check/correct parity, or to reconstruct a missing device.
270 * 'replacing' means we are replacing one or more drives and
271 * the source is valid at this point so we don't need to
272 * read all devices, just the replacement targets.
273 */
274 int syncing, expanding, expanded, replacing;
275 int locked, uptodate, to_read, to_write, failed, written;
276 int to_fill, compute, req_compute, non_overwrite;
277 int injournal, just_cached;
278 int failed_num[2];
279 int p_failed, q_failed;
280 int dec_preread_active;
281 unsigned long ops_request;
282
283 struct md_rdev *blocked_rdev;
284 int handle_bad_blocks;
285 int log_failed;
286 int waiting_extra_page;
287};
288
289/* Flags for struct r5dev.flags */
290enum r5dev_flags {
291 R5_UPTODATE, /* page contains current data */
292 R5_LOCKED, /* IO has been submitted on "req" */
293 R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */
294 R5_OVERWRITE, /* towrite covers whole page */
295/* and some that are internal to handle_stripe */
296 R5_Insync, /* rdev && rdev->in_sync at start */
297 R5_Wantread, /* want to schedule a read */
298 R5_Wantwrite,
299 R5_Overlap, /* There is a pending overlapping request
300 * on this block */
301 R5_ReadNoMerge, /* prevent bio from merging in block-layer */
302 R5_ReadError, /* seen a read error here recently */
303 R5_ReWrite, /* have tried to over-write the readerror */
304
305 R5_Expanded, /* This block now has post-expand data */
306 R5_Wantcompute, /* compute_block in progress treat as
307 * uptodate
308 */
309 R5_Wantfill, /* dev->toread contains a bio that needs
310 * filling
311 */
312 R5_Wantdrain, /* dev->towrite needs to be drained */
313 R5_WantFUA, /* Write should be FUA */
314 R5_SyncIO, /* The IO is sync */
315 R5_WriteError, /* got a write error - need to record it */
316 R5_MadeGood, /* A bad block has been fixed by writing to it */
317 R5_ReadRepl, /* Will/did read from replacement rather than orig */
318 R5_MadeGoodRepl,/* A bad block on the replacement device has been
319 * fixed by writing to it */
320 R5_NeedReplace, /* This device has a replacement which is not
321 * up-to-date at this stripe. */
322 R5_WantReplace, /* We need to update the replacement, we have read
323 * data in, and now is a good time to write it out.
324 */
325 R5_Discard, /* Discard the stripe */
326 R5_SkipCopy, /* Don't copy data from bio to stripe cache */
327 R5_InJournal, /* data being written is in the journal device.
328 * if R5_InJournal is set for parity pd_idx, all the
329 * data and parity being written are in the journal
330 * device
331 */
332 R5_OrigPageUPTDODATE, /* with write back cache, we read old data into
333 * dev->orig_page for prexor. When this flag is
334 * set, orig_page contains latest data in the
335 * raid disk.
336 */
337};
338
339/*
340 * Stripe state
341 */
342enum {
343 STRIPE_ACTIVE,
344 STRIPE_HANDLE,
345 STRIPE_SYNC_REQUESTED,
346 STRIPE_SYNCING,
347 STRIPE_INSYNC,
348 STRIPE_REPLACED,
349 STRIPE_PREREAD_ACTIVE,
350 STRIPE_DELAYED,
351 STRIPE_DEGRADED,
352 STRIPE_BIT_DELAY,
353 STRIPE_EXPANDING,
354 STRIPE_EXPAND_SOURCE,
355 STRIPE_EXPAND_READY,
356 STRIPE_IO_STARTED, /* do not count towards 'bypass_count' */
357 STRIPE_FULL_WRITE, /* all blocks are set to be overwritten */
358 STRIPE_BIOFILL_RUN,
359 STRIPE_COMPUTE_RUN,
360 STRIPE_OPS_REQ_PENDING,
361 STRIPE_ON_UNPLUG_LIST,
362 STRIPE_DISCARD,
363 STRIPE_ON_RELEASE_LIST,
364 STRIPE_BATCH_READY,
365 STRIPE_BATCH_ERR,
366 STRIPE_BITMAP_PENDING, /* Being added to bitmap, don't add
367 * to batch yet.
368 */
369 STRIPE_LOG_TRAPPED, /* trapped into log (see raid5-cache.c)
370 * this bit is used in two scenarios:
371 *
372 * 1. write-out phase
373 * set in first entry of r5l_write_stripe
374 * clear in second entry of r5l_write_stripe
375 * used to bypass logic in handle_stripe
376 *
377 * 2. caching phase
378 * set in r5c_try_caching_write()
379 * clear when journal write is done
380 * used to initiate r5c_cache_data()
381 * also used to bypass logic in handle_stripe
382 */
383 STRIPE_R5C_CACHING, /* the stripe is in caching phase
384 * see more detail in the raid5-cache.c
385 */
386 STRIPE_R5C_PARTIAL_STRIPE, /* in r5c cache (to-be/being handled or
387 * in conf->r5c_partial_stripe_list)
388 */
389 STRIPE_R5C_FULL_STRIPE, /* in r5c cache (to-be/being handled or
390 * in conf->r5c_full_stripe_list)
391 */
392 STRIPE_R5C_PREFLUSH, /* need to flush journal device */
393};
394
395#define STRIPE_EXPAND_SYNC_FLAGS \
396 ((1 << STRIPE_EXPAND_SOURCE) |\
397 (1 << STRIPE_EXPAND_READY) |\
398 (1 << STRIPE_EXPANDING) |\
399 (1 << STRIPE_SYNC_REQUESTED))
400/*
401 * Operation request flags
402 */
403enum {
404 STRIPE_OP_BIOFILL,
405 STRIPE_OP_COMPUTE_BLK,
406 STRIPE_OP_PREXOR,
407 STRIPE_OP_BIODRAIN,
408 STRIPE_OP_RECONSTRUCT,
409 STRIPE_OP_CHECK,
410 STRIPE_OP_PARTIAL_PARITY,
411};
412
413/*
414 * RAID parity calculation preferences
415 */
416enum {
417 PARITY_DISABLE_RMW = 0,
418 PARITY_ENABLE_RMW,
419 PARITY_PREFER_RMW,
420};
421
422/*
423 * Pages requested from set_syndrome_sources()
424 */
425enum {
426 SYNDROME_SRC_ALL,
427 SYNDROME_SRC_WANT_DRAIN,
428 SYNDROME_SRC_WRITTEN,
429};
430/*
431 * Plugging:
432 *
433 * To improve write throughput, we need to delay the handling of some
434 * stripes until there has been a chance that several write requests
435 * for the one stripe have all been collected.
436 * In particular, any write request that would require pre-reading
437 * is put on a "delayed" queue until there are no stripes currently
438 * in a pre-read phase. Further, if the "delayed" queue is empty when
439 * a stripe is put on it then we "plug" the queue and do not process it
440 * until an unplug call is made. (the unplug_io_fn() is called).
441 *
442 * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add
443 * it to the count of prereading stripes.
444 * When write is initiated, or the stripe refcnt == 0 (just in case) we
445 * clear the PREREAD_ACTIVE flag and decrement the count
446 * Whenever the 'handle' queue is empty and the device is not plugged, we
447 * move any strips from delayed to handle and clear the DELAYED flag and set
448 * PREREAD_ACTIVE.
449 * In stripe_handle, if we find pre-reading is necessary, we do it if
450 * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue.
451 * HANDLE gets cleared if stripe_handle leaves nothing locked.
452 */
453
454/* Note: disk_info.rdev can be set to NULL asynchronously by raid5_remove_disk.
455 * There are three safe ways to access disk_info.rdev.
456 * 1/ when holding mddev->reconfig_mutex
457 * 2/ when resync/recovery/reshape is known to be happening - i.e. in code that
458 * is called as part of performing resync/recovery/reshape.
459 * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
460 * and if it is non-NULL, increment rdev->nr_pending before dropping the RCU
461 * lock.
462 * When .rdev is set to NULL, the nr_pending count checked again and if
463 * it has been incremented, the pointer is put back in .rdev.
464 */
465
466struct disk_info {
467 struct md_rdev *rdev, *replacement;
468 struct page *extra_page; /* extra page to use in prexor */
469};
470
471/*
472 * Stripe cache
473 */
474
475#define NR_STRIPES 256
476#define STRIPE_SIZE PAGE_SIZE
477#define STRIPE_SHIFT (PAGE_SHIFT - 9)
478#define STRIPE_SECTORS (STRIPE_SIZE>>9)
479#define IO_THRESHOLD 1
480#define BYPASS_THRESHOLD 1
481#define NR_HASH (PAGE_SIZE / sizeof(struct hlist_head))
482#define HASH_MASK (NR_HASH - 1)
483#define MAX_STRIPE_BATCH 8
484
485/* bio's attached to a stripe+device for I/O are linked together in bi_sector
486 * order without overlap. There may be several bio's per stripe+device, and
487 * a bio could span several devices.
488 * When walking this list for a particular stripe+device, we must never proceed
489 * beyond a bio that extends past this device, as the next bio might no longer
490 * be valid.
491 * This function is used to determine the 'next' bio in the list, given the
492 * sector of the current stripe+device
493 */
494static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
495{
496 int sectors = bio_sectors(bio);
497
498 if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
499 return bio->bi_next;
500 else
501 return NULL;
502}
503
504/* NOTE NR_STRIPE_HASH_LOCKS must remain below 64.
505 * This is because we sometimes take all the spinlocks
506 * and creating that much locking depth can cause
507 * problems.
508 */
509#define NR_STRIPE_HASH_LOCKS 8
510#define STRIPE_HASH_LOCKS_MASK (NR_STRIPE_HASH_LOCKS - 1)
511
512struct r5worker {
513 struct work_struct work;
514 struct r5worker_group *group;
515 struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS];
516 bool working;
517};
518
519struct r5worker_group {
520 struct list_head handle_list;
521 struct list_head loprio_list;
522 struct r5conf *conf;
523 struct r5worker *workers;
524 int stripes_cnt;
525};
526
527/*
528 * r5c journal modes of the array: write-back or write-through.
529 * write-through mode has identical behavior as existing log only
530 * implementation.
531 */
532enum r5c_journal_mode {
533 R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
534 R5C_JOURNAL_MODE_WRITE_BACK = 1,
535};
536
537enum r5_cache_state {
538 R5_INACTIVE_BLOCKED, /* release of inactive stripes blocked,
539 * waiting for 25% to be free
540 */
541 R5_ALLOC_MORE, /* It might help to allocate another
542 * stripe.
543 */
544 R5_DID_ALLOC, /* A stripe was allocated, don't allocate
545 * more until at least one has been
546 * released. This avoids flooding
547 * the cache.
548 */
549 R5C_LOG_TIGHT, /* log device space tight, need to
550 * prioritize stripes at last_checkpoint
551 */
552 R5C_LOG_CRITICAL, /* log device is running out of space,
553 * only process stripes that are already
554 * occupying the log
555 */
556 R5C_EXTRA_PAGE_IN_USE, /* a stripe is using disk_info.extra_page
557 * for prexor
558 */
559};
560
561#define PENDING_IO_MAX 512
562#define PENDING_IO_ONE_FLUSH 128
563struct r5pending_data {
564 struct list_head sibling;
565 sector_t sector; /* stripe sector */
566 struct bio_list bios;
567};
568
569struct r5conf {
570 struct hlist_head *stripe_hashtbl;
571 /* only protect corresponding hash list and inactive_list */
572 spinlock_t hash_locks[NR_STRIPE_HASH_LOCKS];
573 struct mddev *mddev;
574 int chunk_sectors;
575 int level, algorithm, rmw_level;
576 int max_degraded;
577 int raid_disks;
578 int max_nr_stripes;
579 int min_nr_stripes;
580
581 /* reshape_progress is the leading edge of a 'reshape'
582 * It has value MaxSector when no reshape is happening
583 * If delta_disks < 0, it is the last sector we started work on,
584 * else is it the next sector to work on.
585 */
586 sector_t reshape_progress;
587 /* reshape_safe is the trailing edge of a reshape. We know that
588 * before (or after) this address, all reshape has completed.
589 */
590 sector_t reshape_safe;
591 int previous_raid_disks;
592 int prev_chunk_sectors;
593 int prev_algo;
594 short generation; /* increments with every reshape */
595 seqcount_t gen_lock; /* lock against generation changes */
596 unsigned long reshape_checkpoint; /* Time we last updated
597 * metadata */
598 long long min_offset_diff; /* minimum difference between
599 * data_offset and
600 * new_data_offset across all
601 * devices. May be negative,
602 * but is closest to zero.
603 */
604
605 struct list_head handle_list; /* stripes needing handling */
606 struct list_head loprio_list; /* low priority stripes */
607 struct list_head hold_list; /* preread ready stripes */
608 struct list_head delayed_list; /* stripes that have plugged requests */
609 struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */
610 struct bio *retry_read_aligned; /* currently retrying aligned bios */
611 unsigned int retry_read_offset; /* sector offset into retry_read_aligned */
612 struct bio *retry_read_aligned_list; /* aligned bios retry list */
613 atomic_t preread_active_stripes; /* stripes with scheduled io */
614 atomic_t active_aligned_reads;
615 atomic_t pending_full_writes; /* full write backlog */
616 int bypass_count; /* bypassed prereads */
617 int bypass_threshold; /* preread nice */
618 int skip_copy; /* Don't copy data from bio to stripe cache */
619 struct list_head *last_hold; /* detect hold_list promotions */
620
621 atomic_t reshape_stripes; /* stripes with pending writes for reshape */
622 /* unfortunately we need two cache names as we temporarily have
623 * two caches.
624 */
625 int active_name;
626 char cache_name[2][32];
627 struct kmem_cache *slab_cache; /* for allocating stripes */
628 struct mutex cache_size_mutex; /* Protect changes to cache size */
629
630 int seq_flush, seq_write;
631 int quiesce;
632
633 int fullsync; /* set to 1 if a full sync is needed,
634 * (fresh device added).
635 * Cleared when a sync completes.
636 */
637 int recovery_disabled;
638 /* per cpu variables */
639 struct raid5_percpu {
640 struct page *spare_page; /* Used when checking P/Q in raid6 */
641 void *scribble; /* space for constructing buffer
642 * lists and performing address
643 * conversions
644 */
645 int scribble_obj_size;
646 } __percpu *percpu;
647 int scribble_disks;
648 int scribble_sectors;
649 struct hlist_node node;
650
651 /*
652 * Free stripes pool
653 */
654 atomic_t active_stripes;
655 struct list_head inactive_list[NR_STRIPE_HASH_LOCKS];
656
657 atomic_t r5c_cached_full_stripes;
658 struct list_head r5c_full_stripe_list;
659 atomic_t r5c_cached_partial_stripes;
660 struct list_head r5c_partial_stripe_list;
661 atomic_t r5c_flushing_full_stripes;
662 atomic_t r5c_flushing_partial_stripes;
663
664 atomic_t empty_inactive_list_nr;
665 struct llist_head released_stripes;
666 wait_queue_head_t wait_for_quiescent;
667 wait_queue_head_t wait_for_stripe;
668 wait_queue_head_t wait_for_overlap;
669 unsigned long cache_state;
670 struct shrinker shrinker;
671 int pool_size; /* number of disks in stripeheads in pool */
672 spinlock_t device_lock;
673 struct disk_info *disks;
674 struct bio_set bio_split;
675
676 /* When taking over an array from a different personality, we store
677 * the new thread here until we fully activate the array.
678 */
679 struct md_thread *thread;
680 struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS];
681 struct r5worker_group *worker_groups;
682 int group_cnt;
683 int worker_cnt_per_group;
684 struct r5l_log *log;
685 void *log_private;
686
687 spinlock_t pending_bios_lock;
688 bool batch_bio_dispatch;
689 struct r5pending_data *pending_data;
690 struct list_head free_list;
691 struct list_head pending_list;
692 int pending_data_cnt;
693 struct r5pending_data *next_pending_data;
694};
695
696
697/*
698 * Our supported algorithms
699 */
700#define ALGORITHM_LEFT_ASYMMETRIC 0 /* Rotating Parity N with Data Restart */
701#define ALGORITHM_RIGHT_ASYMMETRIC 1 /* Rotating Parity 0 with Data Restart */
702#define ALGORITHM_LEFT_SYMMETRIC 2 /* Rotating Parity N with Data Continuation */
703#define ALGORITHM_RIGHT_SYMMETRIC 3 /* Rotating Parity 0 with Data Continuation */
704
705/* Define non-rotating (raid4) algorithms. These allow
706 * conversion of raid4 to raid5.
707 */
708#define ALGORITHM_PARITY_0 4 /* P or P,Q are initial devices */
709#define ALGORITHM_PARITY_N 5 /* P or P,Q are final devices. */
710
711/* DDF RAID6 layouts differ from md/raid6 layouts in two ways.
712 * Firstly, the exact positioning of the parity block is slightly
713 * different between the 'LEFT_*' modes of md and the "_N_*" modes
714 * of DDF.
715 * Secondly, or order of datablocks over which the Q syndrome is computed
716 * is different.
717 * Consequently we have different layouts for DDF/raid6 than md/raid6.
718 * These layouts are from the DDFv1.2 spec.
719 * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but
720 * leaves RLQ=3 as 'Vendor Specific'
721 */
722
723#define ALGORITHM_ROTATING_ZERO_RESTART 8 /* DDF PRL=6 RLQ=1 */
724#define ALGORITHM_ROTATING_N_RESTART 9 /* DDF PRL=6 RLQ=2 */
725#define ALGORITHM_ROTATING_N_CONTINUE 10 /*DDF PRL=6 RLQ=3 */
726
727/* For every RAID5 algorithm we define a RAID6 algorithm
728 * with exactly the same layout for data and parity, and
729 * with the Q block always on the last device (N-1).
730 * This allows trivial conversion from RAID5 to RAID6
731 */
732#define ALGORITHM_LEFT_ASYMMETRIC_6 16
733#define ALGORITHM_RIGHT_ASYMMETRIC_6 17
734#define ALGORITHM_LEFT_SYMMETRIC_6 18
735#define ALGORITHM_RIGHT_SYMMETRIC_6 19
736#define ALGORITHM_PARITY_0_6 20
737#define ALGORITHM_PARITY_N_6 ALGORITHM_PARITY_N
738
739static inline int algorithm_valid_raid5(int layout)
740{
741 return (layout >= 0) &&
742 (layout <= 5);
743}
744static inline int algorithm_valid_raid6(int layout)
745{
746 return (layout >= 0 && layout <= 5)
747 ||
748 (layout >= 8 && layout <= 10)
749 ||
750 (layout >= 16 && layout <= 20);
751}
752
753static inline int algorithm_is_DDF(int layout)
754{
755 return layout >= 8 && layout <= 10;
756}
757
758extern void md_raid5_kick_device(struct r5conf *conf);
759extern int raid5_set_cache_size(struct mddev *mddev, int size);
760extern sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous);
761extern void raid5_release_stripe(struct stripe_head *sh);
762extern sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
763 int previous, int *dd_idx,
764 struct stripe_head *sh);
765extern struct stripe_head *
766raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
767 int previous, int noblock, int noquiesce);
768extern int raid5_calc_degraded(struct r5conf *conf);
769extern int r5c_journal_mode_set(struct mddev *mddev, int journal_mode);
770#endif
771