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 #include <linux/local_lock.h>
8 
9 /*
10  *
11  * Each stripe contains one buffer per device.  Each buffer can be in
12  * one of a number of states stored in "flags".  Changes between
13  * these states happen *almost* exclusively under the protection of the
14  * STRIPE_ACTIVE flag.  Some very specific changes can happen in bi_end_io, and
15  * these are not protected by STRIPE_ACTIVE.
16  *
17  * The flag bits that are used to represent these states are:
18  *   R5_UPTODATE and R5_LOCKED
19  *
20  * State Empty == !UPTODATE, !LOCK
21  *        We have no data, and there is no active request
22  * State Want == !UPTODATE, LOCK
23  *        A read request is being submitted for this block
24  * State Dirty == UPTODATE, LOCK
25  *        Some new data is in this buffer, and it is being written out
26  * State Clean == UPTODATE, !LOCK
27  *        We have valid data which is the same as on disc
28  *
29  * The possible state transitions are:
30  *
31  *  Empty -> Want   - on read or write to get old data for  parity calc
32  *  Empty -> Dirty  - on compute_parity to satisfy write/sync request.
33  *  Empty -> Clean  - on compute_block when computing a block for failed drive
34  *  Want  -> Empty  - on failed read
35  *  Want  -> Clean  - on successful completion of read request
36  *  Dirty -> Clean  - on successful completion of write request
37  *  Dirty -> Clean  - on failed write
38  *  Clean -> Dirty  - on compute_parity to satisfy write/sync (RECONSTRUCT or RMW)
39  *
40  * The Want->Empty, Want->Clean, Dirty->Clean, transitions
41  * all happen in b_end_io at interrupt time.
42  * Each sets the Uptodate bit before releasing the Lock bit.
43  * This leaves one multi-stage transition:
44  *    Want->Dirty->Clean
45  * This is safe because thinking that a Clean buffer is actually dirty
46  * will at worst delay some action, and the stripe will be scheduled
47  * for attention after the transition is complete.
48  *
49  * There is one possibility that is not covered by these states.  That
50  * is if one drive has failed and there is a spare being rebuilt.  We
51  * can't distinguish between a clean block that has been generated
52  * from parity calculations, and a clean block that has been
53  * successfully written to the spare ( or to parity when resyncing).
54  * To distinguish these states we have a stripe bit STRIPE_INSYNC that
55  * is set whenever a write is scheduled to the spare, or to the parity
56  * disc if there is no spare.  A sync request clears this bit, and
57  * when we find it set with no buffers locked, we know the sync is
58  * complete.
59  *
60  * Buffers for the md device that arrive via make_request are attached
61  * to the appropriate stripe in one of two lists linked on b_reqnext.
62  * One list (bh_read) for read requests, one (bh_write) for write.
63  * There should never be more than one buffer on the two lists
64  * together, but we are not guaranteed of that so we allow for more.
65  *
66  * If a buffer is on the read list when the associated cache buffer is
67  * Uptodate, the data is copied into the read buffer and it's b_end_io
68  * routine is called.  This may happen in the end_request routine only
69  * if the buffer has just successfully been read.  end_request should
70  * remove the buffers from the list and then set the Uptodate bit on
71  * the buffer.  Other threads may do this only if they first check
72  * that the Uptodate bit is set.  Once they have checked that they may
73  * take buffers off the read queue.
74  *
75  * When a buffer on the write list is committed for write it is copied
76  * into the cache buffer, which is then marked dirty, and moved onto a
77  * third list, the written list (bh_written).  Once both the parity
78  * block and the cached buffer are successfully written, any buffer on
79  * a written list can be returned with b_end_io.
80  *
81  * The write list and read list both act as fifos.  The read list,
82  * write list and written list are protected by the device_lock.
83  * The device_lock is only for list manipulations and will only be
84  * held for a very short time.  It can be claimed from interrupts.
85  *
86  *
87  * Stripes in the stripe cache can be on one of two lists (or on
88  * neither).  The "inactive_list" contains stripes which are not
89  * currently being used for any request.  They can freely be reused
90  * for another stripe.  The "handle_list" contains stripes that need
91  * to be handled in some way.  Both of these are fifo queues.  Each
92  * stripe is also (potentially) linked to a hash bucket in the hash
93  * table so that it can be found by sector number.  Stripes that are
94  * not hashed must be on the inactive_list, and will normally be at
95  * the front.  All stripes start life this way.
96  *
97  * The inactive_list, handle_list and hash bucket lists are all protected by the
98  * device_lock.
99  *  - stripes have a reference counter. If count==0, they are on a list.
100  *  - If a stripe might need handling, STRIPE_HANDLE is set.
101  *  - When refcount reaches zero, then if STRIPE_HANDLE it is put on
102  *    handle_list else inactive_list
103  *
104  * This, combined with the fact that STRIPE_HANDLE is only ever
105  * cleared while a stripe has a non-zero count means that if the
106  * refcount is 0 and STRIPE_HANDLE is set, then it is on the
107  * handle_list and if recount is 0 and STRIPE_HANDLE is not set, then
108  * the stripe is on inactive_list.
109  *
110  * The possible transitions are:
111  *  activate an unhashed/inactive stripe (get_active_stripe())
112  *     lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev
113  *  activate a hashed, possibly active stripe (get_active_stripe())
114  *     lockdev check-hash if(!cnt++)unlink-stripe unlockdev
115  *  attach a request to an active stripe (add_stripe_bh())
116  *     lockdev attach-buffer unlockdev
117  *  handle a stripe (handle_stripe())
118  *     setSTRIPE_ACTIVE,  clrSTRIPE_HANDLE ...
119  *		(lockdev check-buffers unlockdev) ..
120  *		change-state ..
121  *		record io/ops needed clearSTRIPE_ACTIVE schedule io/ops
122  *  release an active stripe (release_stripe())
123  *     lockdev if (!--cnt) { if  STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev
124  *
125  * The refcount counts each thread that have activated the stripe,
126  * plus raid5d if it is handling it, plus one for each active request
127  * on a cached buffer, and plus one if the stripe is undergoing stripe
128  * operations.
129  *
130  * The stripe operations are:
131  * -copying data between the stripe cache and user application buffers
132  * -computing blocks to save a disk access, or to recover a missing block
133  * -updating the parity on a write operation (reconstruct write and
134  *  read-modify-write)
135  * -checking parity correctness
136  * -running i/o to disk
137  * These operations are carried out by raid5_run_ops which uses the async_tx
138  * api to (optionally) offload operations to dedicated hardware engines.
139  * When requesting an operation handle_stripe sets the pending bit for the
140  * operation and increments the count.  raid5_run_ops is then run whenever
141  * the count is non-zero.
142  * There are some critical dependencies between the operations that prevent some
143  * from being requested while another is in flight.
144  * 1/ Parity check operations destroy the in cache version of the parity block,
145  *    so we prevent parity dependent operations like writes and compute_blocks
146  *    from starting while a check is in progress.  Some dma engines can perform
147  *    the check without damaging the parity block, in these cases the parity
148  *    block is re-marked up to date (assuming the check was successful) and is
149  *    not re-read from disk.
150  * 2/ When a write operation is requested we immediately lock the affected
151  *    blocks, and mark them as not up to date.  This causes new read requests
152  *    to be held off, as well as parity checks and compute block operations.
153  * 3/ Once a compute block operation has been requested handle_stripe treats
154  *    that block as if it is up to date.  raid5_run_ops guaruntees that any
155  *    operation that is dependent on the compute block result is initiated after
156  *    the compute block completes.
157  */
158 
159 /*
160  * Operations state - intermediate states that are visible outside of
161  *   STRIPE_ACTIVE.
162  * In general _idle indicates nothing is running, _run indicates a data
163  * processing operation is active, and _result means the data processing result
164  * is stable and can be acted upon.  For simple operations like biofill and
165  * compute that only have an _idle and _run state they are indicated with
166  * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN)
167  */
168 /**
169  * enum check_states - handles syncing / repairing a stripe
170  * @check_state_idle - check operations are quiesced
171  * @check_state_run - check operation is running
172  * @check_state_result - set outside lock when check result is valid
173  * @check_state_compute_run - check failed and we are repairing
174  * @check_state_compute_result - set outside lock when compute result is valid
175  */
176 enum check_states {
177 	check_state_idle = 0,
178 	check_state_run, /* xor parity check */
179 	check_state_run_q, /* q-parity check */
180 	check_state_run_pq, /* pq dual parity check */
181 	check_state_check_result,
182 	check_state_compute_run, /* parity repair */
183 	check_state_compute_result,
184 };
185 
186 /**
187  * enum reconstruct_states - handles writing or expanding a stripe
188  */
189 enum reconstruct_states {
190 	reconstruct_state_idle = 0,
191 	reconstruct_state_prexor_drain_run,	/* prexor-write */
192 	reconstruct_state_drain_run,		/* write */
193 	reconstruct_state_run,			/* expand */
194 	reconstruct_state_prexor_drain_result,
195 	reconstruct_state_drain_result,
196 	reconstruct_state_result,
197 };
198 
199 #define DEFAULT_STRIPE_SIZE	4096
200 struct stripe_head {
201 	struct hlist_node	hash;
202 	struct list_head	lru;	      /* inactive_list or handle_list */
203 	struct llist_node	release_list;
204 	struct r5conf		*raid_conf;
205 	short			generation;	/* increments with every
206 						 * reshape */
207 	sector_t		sector;		/* sector of this row */
208 	short			pd_idx;		/* parity disk index */
209 	short			qd_idx;		/* 'Q' disk index for raid6 */
210 	short			ddf_layout;/* use DDF ordering to calculate Q */
211 	short			hash_lock_index;
212 	unsigned long		state;		/* state flags */
213 	atomic_t		count;	      /* nr of active thread/requests */
214 	int			bm_seq;	/* sequence number for bitmap flushes */
215 	int			disks;		/* disks in stripe */
216 	int			overwrite_disks; /* total overwrite disks in stripe,
217 						  * this is only checked when stripe
218 						  * has STRIPE_BATCH_READY
219 						  */
220 	enum check_states	check_state;
221 	enum reconstruct_states reconstruct_state;
222 	spinlock_t		stripe_lock;
223 	int			cpu;
224 	struct r5worker_group	*group;
225 
226 	struct stripe_head	*batch_head; /* protected by stripe lock */
227 	spinlock_t		batch_lock; /* only header's lock is useful */
228 	struct list_head	batch_list; /* protected by head's batch lock*/
229 
230 	union {
231 		struct r5l_io_unit	*log_io;
232 		struct ppl_io_unit	*ppl_io;
233 	};
234 
235 	struct list_head	log_list;
236 	sector_t		log_start; /* first meta block on the journal */
237 	struct list_head	r5c; /* for r5c_cache->stripe_in_journal */
238 
239 	struct page		*ppl_page; /* partial parity of this stripe */
240 	/**
241 	 * struct stripe_operations
242 	 * @target - STRIPE_OP_COMPUTE_BLK target
243 	 * @target2 - 2nd compute target in the raid6 case
244 	 * @zero_sum_result - P and Q verification flags
245 	 * @request - async service request flags for raid_run_ops
246 	 */
247 	struct stripe_operations {
248 		int 		     target, target2;
249 		enum sum_check_flags zero_sum_result;
250 	} ops;
251 
252 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
253 	/* These pages will be used by bios in dev[i] */
254 	struct page	**pages;
255 	int	nr_pages;	/* page array size */
256 	int	stripes_per_page;
257 #endif
258 	struct r5dev {
259 		/* rreq and rvec are used for the replacement device when
260 		 * writing data to both devices.
261 		 */
262 		struct bio	req, rreq;
263 		struct bio_vec	vec, rvec;
264 		struct page	*page, *orig_page;
265 		unsigned int    offset;     /* offset of the page */
266 		struct bio	*toread, *read, *towrite, *written;
267 		sector_t	sector;			/* sector of this page */
268 		unsigned long	flags;
269 		u32		log_checksum;
270 		unsigned short	write_hint;
271 	} dev[]; /* allocated depending of RAID geometry ("disks" member) */
272 };
273 
274 /* stripe_head_state - collects and tracks the dynamic state of a stripe_head
275  *     for handle_stripe.
276  */
277 struct stripe_head_state {
278 	/* 'syncing' means that we need to read all devices, either
279 	 * to check/correct parity, or to reconstruct a missing device.
280 	 * 'replacing' means we are replacing one or more drives and
281 	 * the source is valid at this point so we don't need to
282 	 * read all devices, just the replacement targets.
283 	 */
284 	int syncing, expanding, expanded, replacing;
285 	int locked, uptodate, to_read, to_write, failed, written;
286 	int to_fill, compute, req_compute, non_overwrite;
287 	int injournal, just_cached;
288 	int failed_num[2];
289 	int p_failed, q_failed;
290 	int dec_preread_active;
291 	unsigned long ops_request;
292 
293 	struct md_rdev *blocked_rdev;
294 	int handle_bad_blocks;
295 	int log_failed;
296 	int waiting_extra_page;
297 };
298 
299 /* Flags for struct r5dev.flags */
300 enum r5dev_flags {
301 	R5_UPTODATE,	/* page contains current data */
302 	R5_LOCKED,	/* IO has been submitted on "req" */
303 	R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */
304 	R5_OVERWRITE,	/* towrite covers whole page */
305 /* and some that are internal to handle_stripe */
306 	R5_Insync,	/* rdev && rdev->in_sync at start */
307 	R5_Wantread,	/* want to schedule a read */
308 	R5_Wantwrite,
309 	R5_Overlap,	/* There is a pending overlapping request
310 			 * on this block */
311 	R5_ReadNoMerge, /* prevent bio from merging in block-layer */
312 	R5_ReadError,	/* seen a read error here recently */
313 	R5_ReWrite,	/* have tried to over-write the readerror */
314 
315 	R5_Expanded,	/* This block now has post-expand data */
316 	R5_Wantcompute,	/* compute_block in progress treat as
317 			 * uptodate
318 			 */
319 	R5_Wantfill,	/* dev->toread contains a bio that needs
320 			 * filling
321 			 */
322 	R5_Wantdrain,	/* dev->towrite needs to be drained */
323 	R5_WantFUA,	/* Write should be FUA */
324 	R5_SyncIO,	/* The IO is sync */
325 	R5_WriteError,	/* got a write error - need to record it */
326 	R5_MadeGood,	/* A bad block has been fixed by writing to it */
327 	R5_ReadRepl,	/* Will/did read from replacement rather than orig */
328 	R5_MadeGoodRepl,/* A bad block on the replacement device has been
329 			 * fixed by writing to it */
330 	R5_NeedReplace,	/* This device has a replacement which is not
331 			 * up-to-date at this stripe. */
332 	R5_WantReplace, /* We need to update the replacement, we have read
333 			 * data in, and now is a good time to write it out.
334 			 */
335 	R5_Discard,	/* Discard the stripe */
336 	R5_SkipCopy,	/* Don't copy data from bio to stripe cache */
337 	R5_InJournal,	/* data being written is in the journal device.
338 			 * if R5_InJournal is set for parity pd_idx, all the
339 			 * data and parity being written are in the journal
340 			 * device
341 			 */
342 	R5_OrigPageUPTDODATE,	/* with write back cache, we read old data into
343 				 * dev->orig_page for prexor. When this flag is
344 				 * set, orig_page contains latest data in the
345 				 * raid disk.
346 				 */
347 };
348 
349 /*
350  * Stripe state
351  */
352 enum {
353 	STRIPE_ACTIVE,
354 	STRIPE_HANDLE,
355 	STRIPE_SYNC_REQUESTED,
356 	STRIPE_SYNCING,
357 	STRIPE_INSYNC,
358 	STRIPE_REPLACED,
359 	STRIPE_PREREAD_ACTIVE,
360 	STRIPE_DELAYED,
361 	STRIPE_DEGRADED,
362 	STRIPE_BIT_DELAY,
363 	STRIPE_EXPANDING,
364 	STRIPE_EXPAND_SOURCE,
365 	STRIPE_EXPAND_READY,
366 	STRIPE_IO_STARTED,	/* do not count towards 'bypass_count' */
367 	STRIPE_FULL_WRITE,	/* all blocks are set to be overwritten */
368 	STRIPE_BIOFILL_RUN,
369 	STRIPE_COMPUTE_RUN,
370 	STRIPE_ON_UNPLUG_LIST,
371 	STRIPE_DISCARD,
372 	STRIPE_ON_RELEASE_LIST,
373 	STRIPE_BATCH_READY,
374 	STRIPE_BATCH_ERR,
375 	STRIPE_BITMAP_PENDING,	/* Being added to bitmap, don't add
376 				 * to batch yet.
377 				 */
378 	STRIPE_LOG_TRAPPED,	/* trapped into log (see raid5-cache.c)
379 				 * this bit is used in two scenarios:
380 				 *
381 				 * 1. write-out phase
382 				 *  set in first entry of r5l_write_stripe
383 				 *  clear in second entry of r5l_write_stripe
384 				 *  used to bypass logic in handle_stripe
385 				 *
386 				 * 2. caching phase
387 				 *  set in r5c_try_caching_write()
388 				 *  clear when journal write is done
389 				 *  used to initiate r5c_cache_data()
390 				 *  also used to bypass logic in handle_stripe
391 				 */
392 	STRIPE_R5C_CACHING,	/* the stripe is in caching phase
393 				 * see more detail in the raid5-cache.c
394 				 */
395 	STRIPE_R5C_PARTIAL_STRIPE,	/* in r5c cache (to-be/being handled or
396 					 * in conf->r5c_partial_stripe_list)
397 					 */
398 	STRIPE_R5C_FULL_STRIPE,	/* in r5c cache (to-be/being handled or
399 				 * in conf->r5c_full_stripe_list)
400 				 */
401 	STRIPE_R5C_PREFLUSH,	/* need to flush journal device */
402 };
403 
404 #define STRIPE_EXPAND_SYNC_FLAGS \
405 	((1 << STRIPE_EXPAND_SOURCE) |\
406 	(1 << STRIPE_EXPAND_READY) |\
407 	(1 << STRIPE_EXPANDING) |\
408 	(1 << STRIPE_SYNC_REQUESTED))
409 /*
410  * Operation request flags
411  */
412 enum {
413 	STRIPE_OP_BIOFILL,
414 	STRIPE_OP_COMPUTE_BLK,
415 	STRIPE_OP_PREXOR,
416 	STRIPE_OP_BIODRAIN,
417 	STRIPE_OP_RECONSTRUCT,
418 	STRIPE_OP_CHECK,
419 	STRIPE_OP_PARTIAL_PARITY,
420 };
421 
422 /*
423  * RAID parity calculation preferences
424  */
425 enum {
426 	PARITY_DISABLE_RMW = 0,
427 	PARITY_ENABLE_RMW,
428 	PARITY_PREFER_RMW,
429 };
430 
431 /*
432  * Pages requested from set_syndrome_sources()
433  */
434 enum {
435 	SYNDROME_SRC_ALL,
436 	SYNDROME_SRC_WANT_DRAIN,
437 	SYNDROME_SRC_WRITTEN,
438 };
439 /*
440  * Plugging:
441  *
442  * To improve write throughput, we need to delay the handling of some
443  * stripes until there has been a chance that several write requests
444  * for the one stripe have all been collected.
445  * In particular, any write request that would require pre-reading
446  * is put on a "delayed" queue until there are no stripes currently
447  * in a pre-read phase.  Further, if the "delayed" queue is empty when
448  * a stripe is put on it then we "plug" the queue and do not process it
449  * until an unplug call is made. (the unplug_io_fn() is called).
450  *
451  * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add
452  * it to the count of prereading stripes.
453  * When write is initiated, or the stripe refcnt == 0 (just in case) we
454  * clear the PREREAD_ACTIVE flag and decrement the count
455  * Whenever the 'handle' queue is empty and the device is not plugged, we
456  * move any strips from delayed to handle and clear the DELAYED flag and set
457  * PREREAD_ACTIVE.
458  * In stripe_handle, if we find pre-reading is necessary, we do it if
459  * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue.
460  * HANDLE gets cleared if stripe_handle leaves nothing locked.
461  */
462 
463 /* Note: disk_info.rdev can be set to NULL asynchronously by raid5_remove_disk.
464  * There are three safe ways to access disk_info.rdev.
465  * 1/ when holding mddev->reconfig_mutex
466  * 2/ when resync/recovery/reshape is known to be happening - i.e. in code that
467  *    is called as part of performing resync/recovery/reshape.
468  * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
469  *    and if it is non-NULL, increment rdev->nr_pending before dropping the RCU
470  *    lock.
471  * When .rdev is set to NULL, the nr_pending count checked again and if
472  * it has been incremented, the pointer is put back in .rdev.
473  */
474 
475 struct disk_info {
476 	struct md_rdev	__rcu *rdev;
477 	struct md_rdev  __rcu *replacement;
478 	struct page	*extra_page; /* extra page to use in prexor */
479 };
480 
481 /*
482  * Stripe cache
483  */
484 
485 #define NR_STRIPES		256
486 
487 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE
488 #define STRIPE_SIZE		PAGE_SIZE
489 #define STRIPE_SHIFT		(PAGE_SHIFT - 9)
490 #define STRIPE_SECTORS		(STRIPE_SIZE>>9)
491 #endif
492 
493 #define	IO_THRESHOLD		1
494 #define BYPASS_THRESHOLD	1
495 #define NR_HASH			(PAGE_SIZE / sizeof(struct hlist_head))
496 #define HASH_MASK		(NR_HASH - 1)
497 #define MAX_STRIPE_BATCH	8
498 
499 /* NOTE NR_STRIPE_HASH_LOCKS must remain below 64.
500  * This is because we sometimes take all the spinlocks
501  * and creating that much locking depth can cause
502  * problems.
503  */
504 #define NR_STRIPE_HASH_LOCKS 8
505 #define STRIPE_HASH_LOCKS_MASK (NR_STRIPE_HASH_LOCKS - 1)
506 
507 struct r5worker {
508 	struct work_struct work;
509 	struct r5worker_group *group;
510 	struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS];
511 	bool working;
512 };
513 
514 struct r5worker_group {
515 	struct list_head handle_list;
516 	struct list_head loprio_list;
517 	struct r5conf *conf;
518 	struct r5worker *workers;
519 	int stripes_cnt;
520 };
521 
522 /*
523  * r5c journal modes of the array: write-back or write-through.
524  * write-through mode has identical behavior as existing log only
525  * implementation.
526  */
527 enum r5c_journal_mode {
528 	R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
529 	R5C_JOURNAL_MODE_WRITE_BACK = 1,
530 };
531 
532 enum r5_cache_state {
533 	R5_INACTIVE_BLOCKED,	/* release of inactive stripes blocked,
534 				 * waiting for 25% to be free
535 				 */
536 	R5_ALLOC_MORE,		/* It might help to allocate another
537 				 * stripe.
538 				 */
539 	R5_DID_ALLOC,		/* A stripe was allocated, don't allocate
540 				 * more until at least one has been
541 				 * released.  This avoids flooding
542 				 * the cache.
543 				 */
544 	R5C_LOG_TIGHT,		/* log device space tight, need to
545 				 * prioritize stripes at last_checkpoint
546 				 */
547 	R5C_LOG_CRITICAL,	/* log device is running out of space,
548 				 * only process stripes that are already
549 				 * occupying the log
550 				 */
551 	R5C_EXTRA_PAGE_IN_USE,	/* a stripe is using disk_info.extra_page
552 				 * for prexor
553 				 */
554 };
555 
556 #define PENDING_IO_MAX 512
557 #define PENDING_IO_ONE_FLUSH 128
558 struct r5pending_data {
559 	struct list_head sibling;
560 	sector_t sector; /* stripe sector */
561 	struct bio_list bios;
562 };
563 
564 struct raid5_percpu {
565 	struct page	*spare_page; /* Used when checking P/Q in raid6 */
566 	void		*scribble;  /* space for constructing buffer
567 				     * lists and performing address
568 				     * conversions
569 				     */
570 	int             scribble_obj_size;
571 	local_lock_t    lock;
572 };
573 
574 struct r5conf {
575 	struct hlist_head	*stripe_hashtbl;
576 	/* only protect corresponding hash list and inactive_list */
577 	spinlock_t		hash_locks[NR_STRIPE_HASH_LOCKS];
578 	struct mddev		*mddev;
579 	int			chunk_sectors;
580 	int			level, algorithm, rmw_level;
581 	int			max_degraded;
582 	int			raid_disks;
583 	int			max_nr_stripes;
584 	int			min_nr_stripes;
585 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
586 	unsigned long	stripe_size;
587 	unsigned int	stripe_shift;
588 	unsigned long	stripe_sectors;
589 #endif
590 
591 	/* reshape_progress is the leading edge of a 'reshape'
592 	 * It has value MaxSector when no reshape is happening
593 	 * If delta_disks < 0, it is the last sector we started work on,
594 	 * else is it the next sector to work on.
595 	 */
596 	sector_t		reshape_progress;
597 	/* reshape_safe is the trailing edge of a reshape.  We know that
598 	 * before (or after) this address, all reshape has completed.
599 	 */
600 	sector_t		reshape_safe;
601 	int			previous_raid_disks;
602 	int			prev_chunk_sectors;
603 	int			prev_algo;
604 	short			generation; /* increments with every reshape */
605 	seqcount_spinlock_t	gen_lock;	/* lock against generation changes */
606 	unsigned long		reshape_checkpoint; /* Time we last updated
607 						     * metadata */
608 	long long		min_offset_diff; /* minimum difference between
609 						  * data_offset and
610 						  * new_data_offset across all
611 						  * devices.  May be negative,
612 						  * but is closest to zero.
613 						  */
614 
615 	struct list_head	handle_list; /* stripes needing handling */
616 	struct list_head	loprio_list; /* low priority stripes */
617 	struct list_head	hold_list; /* preread ready stripes */
618 	struct list_head	delayed_list; /* stripes that have plugged requests */
619 	struct list_head	bitmap_list; /* stripes delaying awaiting bitmap update */
620 	struct bio		*retry_read_aligned; /* currently retrying aligned bios   */
621 	unsigned int		retry_read_offset; /* sector offset into retry_read_aligned */
622 	struct bio		*retry_read_aligned_list; /* aligned bios retry list  */
623 	atomic_t		preread_active_stripes; /* stripes with scheduled io */
624 	atomic_t		active_aligned_reads;
625 	atomic_t		pending_full_writes; /* full write backlog */
626 	int			bypass_count; /* bypassed prereads */
627 	int			bypass_threshold; /* preread nice */
628 	int			skip_copy; /* Don't copy data from bio to stripe cache */
629 	struct list_head	*last_hold; /* detect hold_list promotions */
630 
631 	atomic_t		reshape_stripes; /* stripes with pending writes for reshape */
632 	/* unfortunately we need two cache names as we temporarily have
633 	 * two caches.
634 	 */
635 	int			active_name;
636 	char			cache_name[2][32];
637 	struct kmem_cache	*slab_cache; /* for allocating stripes */
638 	struct mutex		cache_size_mutex; /* Protect changes to cache size */
639 
640 	int			seq_flush, seq_write;
641 	int			quiesce;
642 
643 	int			fullsync;  /* set to 1 if a full sync is needed,
644 					    * (fresh device added).
645 					    * Cleared when a sync completes.
646 					    */
647 	int			recovery_disabled;
648 	/* per cpu variables */
649 	struct raid5_percpu __percpu *percpu;
650 	int scribble_disks;
651 	int scribble_sectors;
652 	struct hlist_node node;
653 
654 	/*
655 	 * Free stripes pool
656 	 */
657 	atomic_t		active_stripes;
658 	struct list_head	inactive_list[NR_STRIPE_HASH_LOCKS];
659 
660 	atomic_t		r5c_cached_full_stripes;
661 	struct list_head	r5c_full_stripe_list;
662 	atomic_t		r5c_cached_partial_stripes;
663 	struct list_head	r5c_partial_stripe_list;
664 	atomic_t		r5c_flushing_full_stripes;
665 	atomic_t		r5c_flushing_partial_stripes;
666 
667 	atomic_t		empty_inactive_list_nr;
668 	struct llist_head	released_stripes;
669 	wait_queue_head_t	wait_for_quiescent;
670 	wait_queue_head_t	wait_for_stripe;
671 	wait_queue_head_t	wait_for_overlap;
672 	unsigned long		cache_state;
673 	struct shrinker		shrinker;
674 	int			pool_size; /* number of disks in stripeheads in pool */
675 	spinlock_t		device_lock;
676 	struct disk_info	*disks;
677 	struct bio_set		bio_split;
678 
679 	/* When taking over an array from a different personality, we store
680 	 * the new thread here until we fully activate the array.
681 	 */
682 	struct md_thread __rcu	*thread;
683 	struct list_head	temp_inactive_list[NR_STRIPE_HASH_LOCKS];
684 	struct r5worker_group	*worker_groups;
685 	int			group_cnt;
686 	int			worker_cnt_per_group;
687 	struct r5l_log		*log;
688 	void			*log_private;
689 
690 	spinlock_t		pending_bios_lock;
691 	bool			batch_bio_dispatch;
692 	struct r5pending_data	*pending_data;
693 	struct list_head	free_list;
694 	struct list_head	pending_list;
695 	int			pending_data_cnt;
696 	struct r5pending_data	*next_pending_data;
697 };
698 
699 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE
700 #define RAID5_STRIPE_SIZE(conf)	STRIPE_SIZE
701 #define RAID5_STRIPE_SHIFT(conf)	STRIPE_SHIFT
702 #define RAID5_STRIPE_SECTORS(conf)	STRIPE_SECTORS
703 #else
704 #define RAID5_STRIPE_SIZE(conf)	((conf)->stripe_size)
705 #define RAID5_STRIPE_SHIFT(conf)	((conf)->stripe_shift)
706 #define RAID5_STRIPE_SECTORS(conf)	((conf)->stripe_sectors)
707 #endif
708 
709 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
710  * order without overlap.  There may be several bio's per stripe+device, and
711  * a bio could span several devices.
712  * When walking this list for a particular stripe+device, we must never proceed
713  * beyond a bio that extends past this device, as the next bio might no longer
714  * be valid.
715  * This function is used to determine the 'next' bio in the list, given the
716  * sector of the current stripe+device
717  */
r5_next_bio(struct r5conf * conf,struct bio * bio,sector_t sector)718 static inline struct bio *r5_next_bio(struct r5conf *conf, struct bio *bio, sector_t sector)
719 {
720 	if (bio_end_sector(bio) < sector + RAID5_STRIPE_SECTORS(conf))
721 		return bio->bi_next;
722 	else
723 		return NULL;
724 }
725 
726 /*
727  * Our supported algorithms
728  */
729 #define ALGORITHM_LEFT_ASYMMETRIC	0 /* Rotating Parity N with Data Restart */
730 #define ALGORITHM_RIGHT_ASYMMETRIC	1 /* Rotating Parity 0 with Data Restart */
731 #define ALGORITHM_LEFT_SYMMETRIC	2 /* Rotating Parity N with Data Continuation */
732 #define ALGORITHM_RIGHT_SYMMETRIC	3 /* Rotating Parity 0 with Data Continuation */
733 
734 /* Define non-rotating (raid4) algorithms.  These allow
735  * conversion of raid4 to raid5.
736  */
737 #define ALGORITHM_PARITY_0		4 /* P or P,Q are initial devices */
738 #define ALGORITHM_PARITY_N		5 /* P or P,Q are final devices. */
739 
740 /* DDF RAID6 layouts differ from md/raid6 layouts in two ways.
741  * Firstly, the exact positioning of the parity block is slightly
742  * different between the 'LEFT_*' modes of md and the "_N_*" modes
743  * of DDF.
744  * Secondly, or order of datablocks over which the Q syndrome is computed
745  * is different.
746  * Consequently we have different layouts for DDF/raid6 than md/raid6.
747  * These layouts are from the DDFv1.2 spec.
748  * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but
749  * leaves RLQ=3 as 'Vendor Specific'
750  */
751 
752 #define ALGORITHM_ROTATING_ZERO_RESTART	8 /* DDF PRL=6 RLQ=1 */
753 #define ALGORITHM_ROTATING_N_RESTART	9 /* DDF PRL=6 RLQ=2 */
754 #define ALGORITHM_ROTATING_N_CONTINUE	10 /*DDF PRL=6 RLQ=3 */
755 
756 /* For every RAID5 algorithm we define a RAID6 algorithm
757  * with exactly the same layout for data and parity, and
758  * with the Q block always on the last device (N-1).
759  * This allows trivial conversion from RAID5 to RAID6
760  */
761 #define ALGORITHM_LEFT_ASYMMETRIC_6	16
762 #define ALGORITHM_RIGHT_ASYMMETRIC_6	17
763 #define ALGORITHM_LEFT_SYMMETRIC_6	18
764 #define ALGORITHM_RIGHT_SYMMETRIC_6	19
765 #define ALGORITHM_PARITY_0_6		20
766 #define ALGORITHM_PARITY_N_6		ALGORITHM_PARITY_N
767 
algorithm_valid_raid5(int layout)768 static inline int algorithm_valid_raid5(int layout)
769 {
770 	return (layout >= 0) &&
771 		(layout <= 5);
772 }
algorithm_valid_raid6(int layout)773 static inline int algorithm_valid_raid6(int layout)
774 {
775 	return (layout >= 0 && layout <= 5)
776 		||
777 		(layout >= 8 && layout <= 10)
778 		||
779 		(layout >= 16 && layout <= 20);
780 }
781 
algorithm_is_DDF(int layout)782 static inline int algorithm_is_DDF(int layout)
783 {
784 	return layout >= 8 && layout <= 10;
785 }
786 
787 #if PAGE_SIZE != DEFAULT_STRIPE_SIZE
788 /*
789  * Return offset of the corresponding page for r5dev.
790  */
raid5_get_page_offset(struct stripe_head * sh,int disk_idx)791 static inline int raid5_get_page_offset(struct stripe_head *sh, int disk_idx)
792 {
793 	return (disk_idx % sh->stripes_per_page) * RAID5_STRIPE_SIZE(sh->raid_conf);
794 }
795 
796 /*
797  * Return corresponding page address for r5dev.
798  */
799 static inline struct page *
raid5_get_dev_page(struct stripe_head * sh,int disk_idx)800 raid5_get_dev_page(struct stripe_head *sh, int disk_idx)
801 {
802 	return sh->pages[disk_idx / sh->stripes_per_page];
803 }
804 #endif
805 
806 void md_raid5_kick_device(struct r5conf *conf);
807 int raid5_set_cache_size(struct mddev *mddev, int size);
808 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous);
809 void raid5_release_stripe(struct stripe_head *sh);
810 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
811 		int previous, int *dd_idx, struct stripe_head *sh);
812 
813 struct stripe_request_ctx;
814 /* get stripe from previous generation (when reshaping) */
815 #define R5_GAS_PREVIOUS		(1 << 0)
816 /* do not block waiting for a free stripe */
817 #define R5_GAS_NOBLOCK		(1 << 1)
818 /* do not block waiting for quiesce to be released */
819 #define R5_GAS_NOQUIESCE	(1 << 2)
820 struct stripe_head *raid5_get_active_stripe(struct r5conf *conf,
821 		struct stripe_request_ctx *ctx, sector_t sector,
822 		unsigned int flags);
823 
824 int raid5_calc_degraded(struct r5conf *conf);
825 int r5c_journal_mode_set(struct mddev *mddev, int journal_mode);
826 #endif
827