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1da177e4 LT |
1 | #ifndef _RAID5_H |
2 | #define _RAID5_H | |
3 | ||
4 | #include <linux/raid/md.h> | |
5 | #include <linux/raid/xor.h> | |
6 | ||
7 | /* | |
8 | * | |
9 | * Each stripe contains one buffer per disc. Each buffer can be in | |
10 | * one of a number of states stored in "flags". Changes between | |
11 | * these states happen *almost* exclusively under a per-stripe | |
12 | * spinlock. Some very specific changes can happen in bi_end_io, and | |
13 | * these are not protected by the spin lock. | |
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.(RECONSTRUCT_WRITE) | |
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 is | |
80 | * protected by the device_lock. The write and written lists are | |
81 | * protected by the stripe lock. The device_lock, which can be | |
82 | * claimed while the stipe lock is held, is only for list | |
83 | * manipulations and will only be held for a very short time. It can | |
84 | * 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 on the inactive_list never have their stripe_lock held. | |
100 | * - stripes have a reference counter. If count==0, they are on a list. | |
101 | * - If a stripe might need handling, STRIPE_HANDLE is set. | |
102 | * - When refcount reaches zero, then if STRIPE_HANDLE it is put on | |
103 | * handle_list else inactive_list | |
104 | * | |
105 | * This, combined with the fact that STRIPE_HANDLE is only ever | |
106 | * cleared while a stripe has a non-zero count means that if the | |
107 | * refcount is 0 and STRIPE_HANDLE is set, then it is on the | |
108 | * handle_list and if recount is 0 and STRIPE_HANDLE is not set, then | |
109 | * the stripe is on inactive_list. | |
110 | * | |
111 | * The possible transitions are: | |
112 | * activate an unhashed/inactive stripe (get_active_stripe()) | |
113 | * lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev | |
114 | * activate a hashed, possibly active stripe (get_active_stripe()) | |
115 | * lockdev check-hash if(!cnt++)unlink-stripe unlockdev | |
116 | * attach a request to an active stripe (add_stripe_bh()) | |
117 | * lockdev attach-buffer unlockdev | |
118 | * handle a stripe (handle_stripe()) | |
91c00924 DW |
119 | * lockstripe clrSTRIPE_HANDLE ... |
120 | * (lockdev check-buffers unlockdev) .. | |
121 | * change-state .. | |
122 | * record io/ops needed unlockstripe schedule io/ops | |
1da177e4 LT |
123 | * release an active stripe (release_stripe()) |
124 | * lockdev if (!--cnt) { if STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev | |
125 | * | |
126 | * The refcount counts each thread that have activated the stripe, | |
127 | * plus raid5d if it is handling it, plus one for each active request | |
91c00924 DW |
128 | * on a cached buffer, and plus one if the stripe is undergoing stripe |
129 | * operations. | |
130 | * | |
131 | * Stripe operations are performed outside the stripe lock, | |
132 | * the stripe operations are: | |
133 | * -copying data between the stripe cache and user application buffers | |
134 | * -computing blocks to save a disk access, or to recover a missing block | |
135 | * -updating the parity on a write operation (reconstruct write and | |
136 | * read-modify-write) | |
137 | * -checking parity correctness | |
138 | * -running i/o to disk | |
139 | * These operations are carried out by raid5_run_ops which uses the async_tx | |
140 | * api to (optionally) offload operations to dedicated hardware engines. | |
141 | * When requesting an operation handle_stripe sets the pending bit for the | |
142 | * operation and increments the count. raid5_run_ops is then run whenever | |
143 | * the count is non-zero. | |
144 | * There are some critical dependencies between the operations that prevent some | |
145 | * from being requested while another is in flight. | |
146 | * 1/ Parity check operations destroy the in cache version of the parity block, | |
147 | * so we prevent parity dependent operations like writes and compute_blocks | |
148 | * from starting while a check is in progress. Some dma engines can perform | |
149 | * the check without damaging the parity block, in these cases the parity | |
150 | * block is re-marked up to date (assuming the check was successful) and is | |
151 | * not re-read from disk. | |
152 | * 2/ When a write operation is requested we immediately lock the affected | |
153 | * blocks, and mark them as not up to date. This causes new read requests | |
154 | * to be held off, as well as parity checks and compute block operations. | |
155 | * 3/ Once a compute block operation has been requested handle_stripe treats | |
156 | * that block as if it is up to date. raid5_run_ops guaruntees that any | |
157 | * operation that is dependent on the compute block result is initiated after | |
158 | * the compute block completes. | |
1da177e4 LT |
159 | */ |
160 | ||
ecc65c9b DW |
161 | /* |
162 | * Operations state - intermediate states that are visible outside of sh->lock | |
163 | * In general _idle indicates nothing is running, _run indicates a data | |
164 | * processing operation is active, and _result means the data processing result | |
165 | * is stable and can be acted upon. For simple operations like biofill and | |
166 | * compute that only have an _idle and _run state they are indicated with | |
167 | * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN) | |
168 | */ | |
169 | /** | |
170 | * enum check_states - handles syncing / repairing a stripe | |
171 | * @check_state_idle - check operations are quiesced | |
172 | * @check_state_run - check operation is running | |
173 | * @check_state_result - set outside lock when check result is valid | |
174 | * @check_state_compute_run - check failed and we are repairing | |
175 | * @check_state_compute_result - set outside lock when compute result is valid | |
176 | */ | |
177 | enum check_states { | |
178 | check_state_idle = 0, | |
179 | check_state_run, /* 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 | */ | |
188 | enum reconstruct_states { | |
189 | reconstruct_state_idle = 0, | |
190 | reconstruct_state_drain_run, /* write */ | |
191 | reconstruct_state_run, /* expand */ | |
192 | reconstruct_state_drain_result, | |
193 | reconstruct_state_result, | |
194 | }; | |
195 | ||
1da177e4 | 196 | struct stripe_head { |
fccddba0 | 197 | struct hlist_node hash; |
1da177e4 LT |
198 | struct list_head lru; /* inactive_list or handle_list */ |
199 | struct raid5_private_data *raid_conf; | |
200 | sector_t sector; /* sector of this row */ | |
201 | int pd_idx; /* parity disk index */ | |
202 | unsigned long state; /* state flags */ | |
203 | atomic_t count; /* nr of active thread/requests */ | |
204 | spinlock_t lock; | |
72626685 | 205 | int bm_seq; /* sequence number for bitmap flushes */ |
7ecaa1e6 | 206 | int disks; /* disks in stripe */ |
ecc65c9b | 207 | enum check_states check_state; |
91c00924 DW |
208 | /* stripe_operations |
209 | * @pending - pending ops flags (set for request->issue->complete) | |
210 | * @ack - submitted ops flags (set for issue->complete) | |
211 | * @complete - completed ops flags (set for complete) | |
212 | * @target - STRIPE_OP_COMPUTE_BLK target | |
213 | * @count - raid5_runs_ops is set to run when this is non-zero | |
214 | */ | |
215 | struct stripe_operations { | |
216 | unsigned long pending; | |
217 | unsigned long ack; | |
218 | unsigned long complete; | |
219 | int target; | |
220 | int count; | |
221 | u32 zero_sum_result; | |
222 | } ops; | |
1da177e4 LT |
223 | struct r5dev { |
224 | struct bio req; | |
225 | struct bio_vec vec; | |
226 | struct page *page; | |
91c00924 | 227 | struct bio *toread, *read, *towrite, *written; |
1da177e4 LT |
228 | sector_t sector; /* sector of this page */ |
229 | unsigned long flags; | |
230 | } dev[1]; /* allocated with extra space depending of RAID geometry */ | |
231 | }; | |
a4456856 DW |
232 | |
233 | /* stripe_head_state - collects and tracks the dynamic state of a stripe_head | |
234 | * for handle_stripe. It is only valid under spin_lock(sh->lock); | |
235 | */ | |
236 | struct stripe_head_state { | |
237 | int syncing, expanding, expanded; | |
238 | int locked, uptodate, to_read, to_write, failed, written; | |
b5e98d65 | 239 | int to_fill, compute, req_compute, non_overwrite; |
a4456856 | 240 | int failed_num; |
ecc65c9b | 241 | unsigned long ops_request; |
a4456856 DW |
242 | }; |
243 | ||
244 | /* r6_state - extra state data only relevant to r6 */ | |
245 | struct r6_state { | |
246 | int p_failed, q_failed, qd_idx, failed_num[2]; | |
247 | }; | |
248 | ||
1da177e4 LT |
249 | /* Flags */ |
250 | #define R5_UPTODATE 0 /* page contains current data */ | |
251 | #define R5_LOCKED 1 /* IO has been submitted on "req" */ | |
252 | #define R5_OVERWRITE 2 /* towrite covers whole page */ | |
253 | /* and some that are internal to handle_stripe */ | |
254 | #define R5_Insync 3 /* rdev && rdev->in_sync at start */ | |
255 | #define R5_Wantread 4 /* want to schedule a read */ | |
256 | #define R5_Wantwrite 5 | |
1da177e4 | 257 | #define R5_Overlap 7 /* There is a pending overlapping request on this block */ |
4e5314b5 N |
258 | #define R5_ReadError 8 /* seen a read error here recently */ |
259 | #define R5_ReWrite 9 /* have tried to over-write the readerror */ | |
1da177e4 | 260 | |
ccfcc3c1 | 261 | #define R5_Expanded 10 /* This block now has post-expand data */ |
91c00924 DW |
262 | #define R5_Wantcompute 11 /* compute_block in progress treat as |
263 | * uptodate | |
264 | */ | |
265 | #define R5_Wantfill 12 /* dev->toread contains a bio that needs | |
266 | * filling | |
267 | */ | |
268 | #define R5_Wantprexor 13 /* distinguish blocks ready for rmw from | |
269 | * other "towrites" | |
270 | */ | |
1da177e4 LT |
271 | /* |
272 | * Write method | |
273 | */ | |
274 | #define RECONSTRUCT_WRITE 1 | |
275 | #define READ_MODIFY_WRITE 2 | |
276 | /* not a write method, but a compute_parity mode */ | |
277 | #define CHECK_PARITY 3 | |
278 | ||
279 | /* | |
280 | * Stripe state | |
281 | */ | |
1da177e4 LT |
282 | #define STRIPE_HANDLE 2 |
283 | #define STRIPE_SYNCING 3 | |
284 | #define STRIPE_INSYNC 4 | |
285 | #define STRIPE_PREREAD_ACTIVE 5 | |
286 | #define STRIPE_DELAYED 6 | |
72626685 N |
287 | #define STRIPE_DEGRADED 7 |
288 | #define STRIPE_BIT_DELAY 8 | |
7ecaa1e6 | 289 | #define STRIPE_EXPANDING 9 |
ccfcc3c1 N |
290 | #define STRIPE_EXPAND_SOURCE 10 |
291 | #define STRIPE_EXPAND_READY 11 | |
8b3e6cdc DW |
292 | #define STRIPE_IO_STARTED 12 /* do not count towards 'bypass_count' */ |
293 | #define STRIPE_FULL_WRITE 13 /* all blocks are set to be overwritten */ | |
ecc65c9b DW |
294 | #define STRIPE_BIOFILL_RUN 14 |
295 | #define STRIPE_COMPUTE_RUN 15 | |
91c00924 | 296 | /* |
ecc65c9b | 297 | * Operation request flags |
91c00924 DW |
298 | */ |
299 | #define STRIPE_OP_BIOFILL 0 | |
300 | #define STRIPE_OP_COMPUTE_BLK 1 | |
301 | #define STRIPE_OP_PREXOR 2 | |
302 | #define STRIPE_OP_BIODRAIN 3 | |
303 | #define STRIPE_OP_POSTXOR 4 | |
304 | #define STRIPE_OP_CHECK 5 | |
91c00924 | 305 | |
1da177e4 LT |
306 | /* |
307 | * Plugging: | |
308 | * | |
309 | * To improve write throughput, we need to delay the handling of some | |
310 | * stripes until there has been a chance that several write requests | |
311 | * for the one stripe have all been collected. | |
312 | * In particular, any write request that would require pre-reading | |
313 | * is put on a "delayed" queue until there are no stripes currently | |
314 | * in a pre-read phase. Further, if the "delayed" queue is empty when | |
315 | * a stripe is put on it then we "plug" the queue and do not process it | |
316 | * until an unplug call is made. (the unplug_io_fn() is called). | |
317 | * | |
318 | * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add | |
319 | * it to the count of prereading stripes. | |
320 | * When write is initiated, or the stripe refcnt == 0 (just in case) we | |
321 | * clear the PREREAD_ACTIVE flag and decrement the count | |
b5c124af N |
322 | * Whenever the 'handle' queue is empty and the device is not plugged, we |
323 | * move any strips from delayed to handle and clear the DELAYED flag and set | |
324 | * PREREAD_ACTIVE. | |
1da177e4 LT |
325 | * In stripe_handle, if we find pre-reading is necessary, we do it if |
326 | * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue. | |
327 | * HANDLE gets cleared if stripe_handle leave nothing locked. | |
328 | */ | |
329 | ||
330 | ||
331 | struct disk_info { | |
332 | mdk_rdev_t *rdev; | |
333 | }; | |
334 | ||
335 | struct raid5_private_data { | |
fccddba0 | 336 | struct hlist_head *stripe_hashtbl; |
1da177e4 LT |
337 | mddev_t *mddev; |
338 | struct disk_info *spare; | |
339 | int chunk_size, level, algorithm; | |
16a53ecc | 340 | int max_degraded; |
02c2de8c | 341 | int raid_disks; |
1da177e4 LT |
342 | int max_nr_stripes; |
343 | ||
7ecaa1e6 N |
344 | /* used during an expand */ |
345 | sector_t expand_progress; /* MaxSector when no expand happening */ | |
b578d55f N |
346 | sector_t expand_lo; /* from here up to expand_progress it out-of-bounds |
347 | * as we haven't flushed the metadata yet | |
348 | */ | |
7ecaa1e6 N |
349 | int previous_raid_disks; |
350 | ||
1da177e4 | 351 | struct list_head handle_list; /* stripes needing handling */ |
8b3e6cdc | 352 | struct list_head hold_list; /* preread ready stripes */ |
1da177e4 | 353 | struct list_head delayed_list; /* stripes that have plugged requests */ |
72626685 | 354 | struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */ |
46031f9a RBJ |
355 | struct bio *retry_read_aligned; /* currently retrying aligned bios */ |
356 | struct bio *retry_read_aligned_list; /* aligned bios retry list */ | |
1da177e4 | 357 | atomic_t preread_active_stripes; /* stripes with scheduled io */ |
46031f9a | 358 | atomic_t active_aligned_reads; |
8b3e6cdc DW |
359 | atomic_t pending_full_writes; /* full write backlog */ |
360 | int bypass_count; /* bypassed prereads */ | |
361 | int bypass_threshold; /* preread nice */ | |
362 | struct list_head *last_hold; /* detect hold_list promotions */ | |
1da177e4 | 363 | |
f6705578 | 364 | atomic_t reshape_stripes; /* stripes with pending writes for reshape */ |
ad01c9e3 N |
365 | /* unfortunately we need two cache names as we temporarily have |
366 | * two caches. | |
367 | */ | |
368 | int active_name; | |
369 | char cache_name[2][20]; | |
e18b890b | 370 | struct kmem_cache *slab_cache; /* for allocating stripes */ |
72626685 N |
371 | |
372 | int seq_flush, seq_write; | |
373 | int quiesce; | |
374 | ||
375 | int fullsync; /* set to 1 if a full sync is needed, | |
376 | * (fresh device added). | |
377 | * Cleared when a sync completes. | |
378 | */ | |
379 | ||
ca65b73b N |
380 | struct page *spare_page; /* Used when checking P/Q in raid6 */ |
381 | ||
1da177e4 LT |
382 | /* |
383 | * Free stripes pool | |
384 | */ | |
385 | atomic_t active_stripes; | |
386 | struct list_head inactive_list; | |
387 | wait_queue_head_t wait_for_stripe; | |
388 | wait_queue_head_t wait_for_overlap; | |
389 | int inactive_blocked; /* release of inactive stripes blocked, | |
390 | * waiting for 25% to be free | |
ad01c9e3 N |
391 | */ |
392 | int pool_size; /* number of disks in stripeheads in pool */ | |
1da177e4 | 393 | spinlock_t device_lock; |
b55e6bfc | 394 | struct disk_info *disks; |
1da177e4 LT |
395 | }; |
396 | ||
397 | typedef struct raid5_private_data raid5_conf_t; | |
398 | ||
399 | #define mddev_to_conf(mddev) ((raid5_conf_t *) mddev->private) | |
400 | ||
401 | /* | |
402 | * Our supported algorithms | |
403 | */ | |
404 | #define ALGORITHM_LEFT_ASYMMETRIC 0 | |
405 | #define ALGORITHM_RIGHT_ASYMMETRIC 1 | |
406 | #define ALGORITHM_LEFT_SYMMETRIC 2 | |
407 | #define ALGORITHM_RIGHT_SYMMETRIC 3 | |
408 | ||
409 | #endif |