1 #ifndef _RAID5_H
2 #define _RAID5_H
3 
4 #include <linux/raid/xor.h>
5 #include <linux/dmaengine.h>
6 
7 /*
8  *
9  * Each stripe contains one buffer per device.  Each buffer can be in
10  * one of a number of states stored in "flags".  Changes between
11  * these states happen *almost* exclusively under the protection of the
12  * STRIPE_ACTIVE flag.  Some very specific changes can happen in bi_end_io, and
13  * these are not protected by STRIPE_ACTIVE.
14  *
15  * The flag bits that are used to represent these states are:
16  *   R5_UPTODATE and R5_LOCKED
17  *
18  * State Empty == !UPTODATE, !LOCK
19  *        We have no data, and there is no active request
20  * State Want == !UPTODATE, LOCK
21  *        A read request is being submitted for this block
22  * State Dirty == UPTODATE, LOCK
23  *        Some new data is in this buffer, and it is being written out
24  * State Clean == UPTODATE, !LOCK
25  *        We have valid data which is the same as on disc
26  *
27  * The possible state transitions are:
28  *
29  *  Empty -> Want   - on read or write to get old data for  parity calc
30  *  Empty -> Dirty  - on compute_parity to satisfy write/sync request.
31  *  Empty -> Clean  - on compute_block when computing a block for failed drive
32  *  Want  -> Empty  - on failed read
33  *  Want  -> Clean  - on successful completion of read request
34  *  Dirty -> Clean  - on successful completion of write request
35  *  Dirty -> Clean  - on failed write
36  *  Clean -> Dirty  - on compute_parity to satisfy write/sync (RECONSTRUCT or RMW)
37  *
38  * The Want->Empty, Want->Clean, Dirty->Clean, transitions
39  * all happen in b_end_io at interrupt time.
40  * Each sets the Uptodate bit before releasing the Lock bit.
41  * This leaves one multi-stage transition:
42  *    Want->Dirty->Clean
43  * This is safe because thinking that a Clean buffer is actually dirty
44  * will at worst delay some action, and the stripe will be scheduled
45  * for attention after the transition is complete.
46  *
47  * There is one possibility that is not covered by these states.  That
48  * is if one drive has failed and there is a spare being rebuilt.  We
49  * can't distinguish between a clean block that has been generated
50  * from parity calculations, and a clean block that has been
51  * successfully written to the spare ( or to parity when resyncing).
52  * To distingush these states we have a stripe bit STRIPE_INSYNC that
53  * is set whenever a write is scheduled to the spare, or to the parity
54  * disc if there is no spare.  A sync request clears this bit, and
55  * when we find it set with no buffers locked, we know the sync is
56  * complete.
57  *
58  * Buffers for the md device that arrive via make_request are attached
59  * to the appropriate stripe in one of two lists linked on b_reqnext.
60  * One list (bh_read) for read requests, one (bh_write) for write.
61  * There should never be more than one buffer on the two lists
62  * together, but we are not guaranteed of that so we allow for more.
63  *
64  * If a buffer is on the read list when the associated cache buffer is
65  * Uptodate, the data is copied into the read buffer and it's b_end_io
66  * routine is called.  This may happen in the end_request routine only
67  * if the buffer has just successfully been read.  end_request should
68  * remove the buffers from the list and then set the Uptodate bit on
69  * the buffer.  Other threads may do this only if they first check
70  * that the Uptodate bit is set.  Once they have checked that they may
71  * take buffers off the read queue.
72  *
73  * When a buffer on the write list is committed for write it is copied
74  * into the cache buffer, which is then marked dirty, and moved onto a
75  * third list, the written list (bh_written).  Once both the parity
76  * block and the cached buffer are successfully written, any buffer on
77  * a written list can be returned with b_end_io.
78  *
79  * The write list and read list both act as fifos.  The read list,
80  * write list and written list are protected by the device_lock.
81  * The device_lock is only for list manipulations and will only be
82  * held for a very short time.  It can be claimed from interrupts.
83  *
84  *
85  * Stripes in the stripe cache can be on one of two lists (or on
86  * neither).  The "inactive_list" contains stripes which are not
87  * currently being used for any request.  They can freely be reused
88  * for another stripe.  The "handle_list" contains stripes that need
89  * to be handled in some way.  Both of these are fifo queues.  Each
90  * stripe is also (potentially) linked to a hash bucket in the hash
91  * table so that it can be found by sector number.  Stripes that are
92  * not hashed must be on the inactive_list, and will normally be at
93  * the front.  All stripes start life this way.
94  *
95  * The inactive_list, handle_list and hash bucket lists are all protected by the
96  * device_lock.
97  *  - stripes have a reference counter. If count==0, they are on a list.
98  *  - If a stripe might need handling, STRIPE_HANDLE is set.
99  *  - When refcount reaches zero, then if STRIPE_HANDLE it is put on
100  *    handle_list else inactive_list
101  *
102  * This, combined with the fact that STRIPE_HANDLE is only ever
103  * cleared while a stripe has a non-zero count means that if the
104  * refcount is 0 and STRIPE_HANDLE is set, then it is on the
105  * handle_list and if recount is 0 and STRIPE_HANDLE is not set, then
106  * the stripe is on inactive_list.
107  *
108  * The possible transitions are:
109  *  activate an unhashed/inactive stripe (get_active_stripe())
110  *     lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev
111  *  activate a hashed, possibly active stripe (get_active_stripe())
112  *     lockdev check-hash if(!cnt++)unlink-stripe unlockdev
113  *  attach a request to an active stripe (add_stripe_bh())
114  *     lockdev attach-buffer unlockdev
115  *  handle a stripe (handle_stripe())
116  *     setSTRIPE_ACTIVE,  clrSTRIPE_HANDLE ...
117  *		(lockdev check-buffers unlockdev) ..
118  *		change-state ..
119  *		record io/ops needed clearSTRIPE_ACTIVE schedule io/ops
120  *  release an active stripe (release_stripe())
121  *     lockdev if (!--cnt) { if  STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev
122  *
123  * The refcount counts each thread that have activated the stripe,
124  * plus raid5d if it is handling it, plus one for each active request
125  * on a cached buffer, and plus one if the stripe is undergoing stripe
126  * operations.
127  *
128  * The stripe operations are:
129  * -copying data between the stripe cache and user application buffers
130  * -computing blocks to save a disk access, or to recover a missing block
131  * -updating the parity on a write operation (reconstruct write and
132  *  read-modify-write)
133  * -checking parity correctness
134  * -running i/o to disk
135  * These operations are carried out by raid5_run_ops which uses the async_tx
136  * api to (optionally) offload operations to dedicated hardware engines.
137  * When requesting an operation handle_stripe sets the pending bit for the
138  * operation and increments the count.  raid5_run_ops is then run whenever
139  * the count is non-zero.
140  * There are some critical dependencies between the operations that prevent some
141  * from being requested while another is in flight.
142  * 1/ Parity check operations destroy the in cache version of the parity block,
143  *    so we prevent parity dependent operations like writes and compute_blocks
144  *    from starting while a check is in progress.  Some dma engines can perform
145  *    the check without damaging the parity block, in these cases the parity
146  *    block is re-marked up to date (assuming the check was successful) and is
147  *    not re-read from disk.
148  * 2/ When a write operation is requested we immediately lock the affected
149  *    blocks, and mark them as not up to date.  This causes new read requests
150  *    to be held off, as well as parity checks and compute block operations.
151  * 3/ Once a compute block operation has been requested handle_stripe treats
152  *    that block as if it is up to date.  raid5_run_ops guaruntees that any
153  *    operation that is dependent on the compute block result is initiated after
154  *    the compute block completes.
155  */
156 
157 /*
158  * Operations state - intermediate states that are visible outside of
159  *   STRIPE_ACTIVE.
160  * In general _idle indicates nothing is running, _run indicates a data
161  * processing operation is active, and _result means the data processing result
162  * is stable and can be acted upon.  For simple operations like biofill and
163  * compute that only have an _idle and _run state they are indicated with
164  * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN)
165  */
166 /**
167  * enum check_states - handles syncing / repairing a stripe
168  * @check_state_idle - check operations are quiesced
169  * @check_state_run - check operation is running
170  * @check_state_result - set outside lock when check result is valid
171  * @check_state_compute_run - check failed and we are repairing
172  * @check_state_compute_result - set outside lock when compute result is valid
173  */
174 enum check_states {
175 	check_state_idle = 0,
176 	check_state_run, /* xor parity check */
177 	check_state_run_q, /* q-parity check */
178 	check_state_run_pq, /* pq dual parity check */
179 	check_state_check_result,
180 	check_state_compute_run, /* parity repair */
181 	check_state_compute_result,
182 };
183 
184 /**
185  * enum reconstruct_states - handles writing or expanding a stripe
186  */
187 enum reconstruct_states {
188 	reconstruct_state_idle = 0,
189 	reconstruct_state_prexor_drain_run,	/* prexor-write */
190 	reconstruct_state_drain_run,		/* write */
191 	reconstruct_state_run,			/* expand */
192 	reconstruct_state_prexor_drain_result,
193 	reconstruct_state_drain_result,
194 	reconstruct_state_result,
195 };
196 
197 struct stripe_head {
198 	struct hlist_node	hash;
199 	struct list_head	lru;	      /* inactive_list or handle_list */
200 	struct r5conf		*raid_conf;
201 	short			generation;	/* increments with every
202 						 * reshape */
203 	sector_t		sector;		/* sector of this row */
204 	short			pd_idx;		/* parity disk index */
205 	short			qd_idx;		/* 'Q' disk index for raid6 */
206 	short			ddf_layout;/* use DDF ordering to calculate Q */
207 	unsigned long		state;		/* state flags */
208 	atomic_t		count;	      /* nr of active thread/requests */
209 	int			bm_seq;	/* sequence number for bitmap flushes */
210 	int			disks;		/* disks in stripe */
211 	enum check_states	check_state;
212 	enum reconstruct_states reconstruct_state;
213 	/**
214 	 * struct stripe_operations
215 	 * @target - STRIPE_OP_COMPUTE_BLK target
216 	 * @target2 - 2nd compute target in the raid6 case
217 	 * @zero_sum_result - P and Q verification flags
218 	 * @request - async service request flags for raid_run_ops
219 	 */
220 	struct stripe_operations {
221 		int 		     target, target2;
222 		enum sum_check_flags zero_sum_result;
223 		#ifdef CONFIG_MULTICORE_RAID456
224 		unsigned long	     request;
225 		wait_queue_head_t    wait_for_ops;
226 		#endif
227 	} ops;
228 	struct r5dev {
229 		/* rreq and rvec are used for the replacement device when
230 		 * writing data to both devices.
231 		 */
232 		struct bio	req, rreq;
233 		struct bio_vec	vec, rvec;
234 		struct page	*page;
235 		struct bio	*toread, *read, *towrite, *written;
236 		sector_t	sector;			/* sector of this page */
237 		unsigned long	flags;
238 	} dev[1]; /* allocated with extra space depending of RAID geometry */
239 };
240 
241 /* stripe_head_state - collects and tracks the dynamic state of a stripe_head
242  *     for handle_stripe.
243  */
244 struct stripe_head_state {
245 	/* 'syncing' means that we need to read all devices, either
246 	 * to check/correct parity, or to reconstruct a missing device.
247 	 * 'replacing' means we are replacing one or more drives and
248 	 * the source is valid at this point so we don't need to
249 	 * read all devices, just the replacement targets.
250 	 */
251 	int syncing, expanding, expanded, replacing;
252 	int locked, uptodate, to_read, to_write, failed, written;
253 	int to_fill, compute, req_compute, non_overwrite;
254 	int failed_num[2];
255 	int p_failed, q_failed;
256 	int dec_preread_active;
257 	unsigned long ops_request;
258 
259 	struct bio *return_bi;
260 	struct md_rdev *blocked_rdev;
261 	int handle_bad_blocks;
262 };
263 
264 /* Flags for struct r5dev.flags */
265 enum r5dev_flags {
266 	R5_UPTODATE,	/* page contains current data */
267 	R5_LOCKED,	/* IO has been submitted on "req" */
268 	R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */
269 	R5_OVERWRITE,	/* towrite covers whole page */
270 /* and some that are internal to handle_stripe */
271 	R5_Insync,	/* rdev && rdev->in_sync at start */
272 	R5_Wantread,	/* want to schedule a read */
273 	R5_Wantwrite,
274 	R5_Overlap,	/* There is a pending overlapping request
275 			 * on this block */
276 	R5_ReadError,	/* seen a read error here recently */
277 	R5_ReWrite,	/* have tried to over-write the readerror */
278 
279 	R5_Expanded,	/* This block now has post-expand data */
280 	R5_Wantcompute,	/* compute_block in progress treat as
281 			 * uptodate
282 			 */
283 	R5_Wantfill,	/* dev->toread contains a bio that needs
284 			 * filling
285 			 */
286 	R5_Wantdrain,	/* dev->towrite needs to be drained */
287 	R5_WantFUA,	/* Write should be FUA */
288 	R5_WriteError,	/* got a write error - need to record it */
289 	R5_MadeGood,	/* A bad block has been fixed by writing to it */
290 	R5_ReadRepl,	/* Will/did read from replacement rather than orig */
291 	R5_MadeGoodRepl,/* A bad block on the replacement device has been
292 			 * fixed by writing to it */
293 	R5_NeedReplace,	/* This device has a replacement which is not
294 			 * up-to-date at this stripe. */
295 	R5_WantReplace, /* We need to update the replacement, we have read
296 			 * data in, and now is a good time to write it out.
297 			 */
298 };
299 
300 /*
301  * Stripe state
302  */
303 enum {
304 	STRIPE_ACTIVE,
305 	STRIPE_HANDLE,
306 	STRIPE_SYNC_REQUESTED,
307 	STRIPE_SYNCING,
308 	STRIPE_INSYNC,
309 	STRIPE_REPLACED,
310 	STRIPE_PREREAD_ACTIVE,
311 	STRIPE_DELAYED,
312 	STRIPE_DEGRADED,
313 	STRIPE_BIT_DELAY,
314 	STRIPE_EXPANDING,
315 	STRIPE_EXPAND_SOURCE,
316 	STRIPE_EXPAND_READY,
317 	STRIPE_IO_STARTED,	/* do not count towards 'bypass_count' */
318 	STRIPE_FULL_WRITE,	/* all blocks are set to be overwritten */
319 	STRIPE_BIOFILL_RUN,
320 	STRIPE_COMPUTE_RUN,
321 	STRIPE_OPS_REQ_PENDING,
322 };
323 
324 /*
325  * Operation request flags
326  */
327 enum {
328 	STRIPE_OP_BIOFILL,
329 	STRIPE_OP_COMPUTE_BLK,
330 	STRIPE_OP_PREXOR,
331 	STRIPE_OP_BIODRAIN,
332 	STRIPE_OP_RECONSTRUCT,
333 	STRIPE_OP_CHECK,
334 };
335 /*
336  * Plugging:
337  *
338  * To improve write throughput, we need to delay the handling of some
339  * stripes until there has been a chance that several write requests
340  * for the one stripe have all been collected.
341  * In particular, any write request that would require pre-reading
342  * is put on a "delayed" queue until there are no stripes currently
343  * in a pre-read phase.  Further, if the "delayed" queue is empty when
344  * a stripe is put on it then we "plug" the queue and do not process it
345  * until an unplug call is made. (the unplug_io_fn() is called).
346  *
347  * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add
348  * it to the count of prereading stripes.
349  * When write is initiated, or the stripe refcnt == 0 (just in case) we
350  * clear the PREREAD_ACTIVE flag and decrement the count
351  * Whenever the 'handle' queue is empty and the device is not plugged, we
352  * move any strips from delayed to handle and clear the DELAYED flag and set
353  * PREREAD_ACTIVE.
354  * In stripe_handle, if we find pre-reading is necessary, we do it if
355  * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue.
356  * HANDLE gets cleared if stripe_handle leaves nothing locked.
357  */
358 
359 
360 struct disk_info {
361 	struct md_rdev	*rdev, *replacement;
362 };
363 
364 struct r5conf {
365 	struct hlist_head	*stripe_hashtbl;
366 	struct mddev		*mddev;
367 	int			chunk_sectors;
368 	int			level, algorithm;
369 	int			max_degraded;
370 	int			raid_disks;
371 	int			max_nr_stripes;
372 
373 	/* reshape_progress is the leading edge of a 'reshape'
374 	 * It has value MaxSector when no reshape is happening
375 	 * If delta_disks < 0, it is the last sector we started work on,
376 	 * else is it the next sector to work on.
377 	 */
378 	sector_t		reshape_progress;
379 	/* reshape_safe is the trailing edge of a reshape.  We know that
380 	 * before (or after) this address, all reshape has completed.
381 	 */
382 	sector_t		reshape_safe;
383 	int			previous_raid_disks;
384 	int			prev_chunk_sectors;
385 	int			prev_algo;
386 	short			generation; /* increments with every reshape */
387 	unsigned long		reshape_checkpoint; /* Time we last updated
388 						     * metadata */
389 
390 	struct list_head	handle_list; /* stripes needing handling */
391 	struct list_head	hold_list; /* preread ready stripes */
392 	struct list_head	delayed_list; /* stripes that have plugged requests */
393 	struct list_head	bitmap_list; /* stripes delaying awaiting bitmap update */
394 	struct bio		*retry_read_aligned; /* currently retrying aligned bios   */
395 	struct bio		*retry_read_aligned_list; /* aligned bios retry list  */
396 	atomic_t		preread_active_stripes; /* stripes with scheduled io */
397 	atomic_t		active_aligned_reads;
398 	atomic_t		pending_full_writes; /* full write backlog */
399 	int			bypass_count; /* bypassed prereads */
400 	int			bypass_threshold; /* preread nice */
401 	struct list_head	*last_hold; /* detect hold_list promotions */
402 
403 	atomic_t		reshape_stripes; /* stripes with pending writes for reshape */
404 	/* unfortunately we need two cache names as we temporarily have
405 	 * two caches.
406 	 */
407 	int			active_name;
408 	char			cache_name[2][32];
409 	struct kmem_cache		*slab_cache; /* for allocating stripes */
410 
411 	int			seq_flush, seq_write;
412 	int			quiesce;
413 
414 	int			fullsync;  /* set to 1 if a full sync is needed,
415 					    * (fresh device added).
416 					    * Cleared when a sync completes.
417 					    */
418 	int			recovery_disabled;
419 	/* per cpu variables */
420 	struct raid5_percpu {
421 		struct page	*spare_page; /* Used when checking P/Q in raid6 */
422 		void		*scribble;   /* space for constructing buffer
423 					      * lists and performing address
424 					      * conversions
425 					      */
426 	} __percpu *percpu;
427 	size_t			scribble_len; /* size of scribble region must be
428 					       * associated with conf to handle
429 					       * cpu hotplug while reshaping
430 					       */
431 #ifdef CONFIG_HOTPLUG_CPU
432 	struct notifier_block	cpu_notify;
433 #endif
434 
435 	/*
436 	 * Free stripes pool
437 	 */
438 	atomic_t		active_stripes;
439 	struct list_head	inactive_list;
440 	wait_queue_head_t	wait_for_stripe;
441 	wait_queue_head_t	wait_for_overlap;
442 	int			inactive_blocked;	/* release of inactive stripes blocked,
443 							 * waiting for 25% to be free
444 							 */
445 	int			pool_size; /* number of disks in stripeheads in pool */
446 	spinlock_t		device_lock;
447 	struct disk_info	*disks;
448 
449 	/* When taking over an array from a different personality, we store
450 	 * the new thread here until we fully activate the array.
451 	 */
452 	struct md_thread	*thread;
453 };
454 
455 /*
456  * Our supported algorithms
457  */
458 #define ALGORITHM_LEFT_ASYMMETRIC	0 /* Rotating Parity N with Data Restart */
459 #define ALGORITHM_RIGHT_ASYMMETRIC	1 /* Rotating Parity 0 with Data Restart */
460 #define ALGORITHM_LEFT_SYMMETRIC	2 /* Rotating Parity N with Data Continuation */
461 #define ALGORITHM_RIGHT_SYMMETRIC	3 /* Rotating Parity 0 with Data Continuation */
462 
463 /* Define non-rotating (raid4) algorithms.  These allow
464  * conversion of raid4 to raid5.
465  */
466 #define ALGORITHM_PARITY_0		4 /* P or P,Q are initial devices */
467 #define ALGORITHM_PARITY_N		5 /* P or P,Q are final devices. */
468 
469 /* DDF RAID6 layouts differ from md/raid6 layouts in two ways.
470  * Firstly, the exact positioning of the parity block is slightly
471  * different between the 'LEFT_*' modes of md and the "_N_*" modes
472  * of DDF.
473  * Secondly, or order of datablocks over which the Q syndrome is computed
474  * is different.
475  * Consequently we have different layouts for DDF/raid6 than md/raid6.
476  * These layouts are from the DDFv1.2 spec.
477  * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but
478  * leaves RLQ=3 as 'Vendor Specific'
479  */
480 
481 #define ALGORITHM_ROTATING_ZERO_RESTART	8 /* DDF PRL=6 RLQ=1 */
482 #define ALGORITHM_ROTATING_N_RESTART	9 /* DDF PRL=6 RLQ=2 */
483 #define ALGORITHM_ROTATING_N_CONTINUE	10 /*DDF PRL=6 RLQ=3 */
484 
485 
486 /* For every RAID5 algorithm we define a RAID6 algorithm
487  * with exactly the same layout for data and parity, and
488  * with the Q block always on the last device (N-1).
489  * This allows trivial conversion from RAID5 to RAID6
490  */
491 #define ALGORITHM_LEFT_ASYMMETRIC_6	16
492 #define ALGORITHM_RIGHT_ASYMMETRIC_6	17
493 #define ALGORITHM_LEFT_SYMMETRIC_6	18
494 #define ALGORITHM_RIGHT_SYMMETRIC_6	19
495 #define ALGORITHM_PARITY_0_6		20
496 #define ALGORITHM_PARITY_N_6		ALGORITHM_PARITY_N
497 
algorithm_valid_raid5(int layout)498 static inline int algorithm_valid_raid5(int layout)
499 {
500 	return (layout >= 0) &&
501 		(layout <= 5);
502 }
algorithm_valid_raid6(int layout)503 static inline int algorithm_valid_raid6(int layout)
504 {
505 	return (layout >= 0 && layout <= 5)
506 		||
507 		(layout >= 8 && layout <= 10)
508 		||
509 		(layout >= 16 && layout <= 20);
510 }
511 
algorithm_is_DDF(int layout)512 static inline int algorithm_is_DDF(int layout)
513 {
514 	return layout >= 8 && layout <= 10;
515 }
516 
517 extern int md_raid5_congested(struct mddev *mddev, int bits);
518 extern void md_raid5_kick_device(struct r5conf *conf);
519 extern int raid5_set_cache_size(struct mddev *mddev, int size);
520 #endif
521