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 spinlock_t stripe_lock; 214 /** 215 * struct stripe_operations 216 * @target - STRIPE_OP_COMPUTE_BLK target 217 * @target2 - 2nd compute target in the raid6 case 218 * @zero_sum_result - P and Q verification flags 219 * @request - async service request flags for raid_run_ops 220 */ 221 struct stripe_operations { 222 int target, target2; 223 enum sum_check_flags zero_sum_result; 224 } ops; 225 struct r5dev { 226 /* rreq and rvec are used for the replacement device when 227 * writing data to both devices. 228 */ 229 struct bio req, rreq; 230 struct bio_vec vec, rvec; 231 struct page *page; 232 struct bio *toread, *read, *towrite, *written; 233 sector_t sector; /* sector of this page */ 234 unsigned long flags; 235 } dev[1]; /* allocated with extra space depending of RAID geometry */ 236 }; 237 238 /* stripe_head_state - collects and tracks the dynamic state of a stripe_head 239 * for handle_stripe. 240 */ 241 struct stripe_head_state { 242 /* 'syncing' means that we need to read all devices, either 243 * to check/correct parity, or to reconstruct a missing device. 244 * 'replacing' means we are replacing one or more drives and 245 * the source is valid at this point so we don't need to 246 * read all devices, just the replacement targets. 247 */ 248 int syncing, expanding, expanded, replacing; 249 int locked, uptodate, to_read, to_write, failed, written; 250 int to_fill, compute, req_compute, non_overwrite; 251 int failed_num[2]; 252 int p_failed, q_failed; 253 int dec_preread_active; 254 unsigned long ops_request; 255 256 struct bio *return_bi; 257 struct md_rdev *blocked_rdev; 258 int handle_bad_blocks; 259 }; 260 261 /* Flags for struct r5dev.flags */ 262 enum r5dev_flags { 263 R5_UPTODATE, /* page contains current data */ 264 R5_LOCKED, /* IO has been submitted on "req" */ 265 R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */ 266 R5_OVERWRITE, /* towrite covers whole page */ 267 /* and some that are internal to handle_stripe */ 268 R5_Insync, /* rdev && rdev->in_sync at start */ 269 R5_Wantread, /* want to schedule a read */ 270 R5_Wantwrite, 271 R5_Overlap, /* There is a pending overlapping request 272 * on this block */ 273 R5_ReadNoMerge, /* prevent bio from merging in block-layer */ 274 R5_ReadError, /* seen a read error here recently */ 275 R5_ReWrite, /* have tried to over-write the readerror */ 276 277 R5_Expanded, /* This block now has post-expand data */ 278 R5_Wantcompute, /* compute_block in progress treat as 279 * uptodate 280 */ 281 R5_Wantfill, /* dev->toread contains a bio that needs 282 * filling 283 */ 284 R5_Wantdrain, /* dev->towrite needs to be drained */ 285 R5_WantFUA, /* Write should be FUA */ 286 R5_SyncIO, /* The IO is sync */ 287 R5_WriteError, /* got a write error - need to record it */ 288 R5_MadeGood, /* A bad block has been fixed by writing to it */ 289 R5_ReadRepl, /* Will/did read from replacement rather than orig */ 290 R5_MadeGoodRepl,/* A bad block on the replacement device has been 291 * fixed by writing to it */ 292 R5_NeedReplace, /* This device has a replacement which is not 293 * up-to-date at this stripe. */ 294 R5_WantReplace, /* We need to update the replacement, we have read 295 * data in, and now is a good time to write it out. 296 */ 297 R5_Discard, /* Discard the stripe */ 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_PREREAD_ACTIVE, 310 STRIPE_DELAYED, 311 STRIPE_DEGRADED, 312 STRIPE_BIT_DELAY, 313 STRIPE_EXPANDING, 314 STRIPE_EXPAND_SOURCE, 315 STRIPE_EXPAND_READY, 316 STRIPE_IO_STARTED, /* do not count towards 'bypass_count' */ 317 STRIPE_FULL_WRITE, /* all blocks are set to be overwritten */ 318 STRIPE_BIOFILL_RUN, 319 STRIPE_COMPUTE_RUN, 320 STRIPE_OPS_REQ_PENDING, 321 STRIPE_ON_UNPLUG_LIST, 322 STRIPE_DISCARD, 323 }; 324 325 /* 326 * Operation request flags 327 */ 328 enum { 329 STRIPE_OP_BIOFILL, 330 STRIPE_OP_COMPUTE_BLK, 331 STRIPE_OP_PREXOR, 332 STRIPE_OP_BIODRAIN, 333 STRIPE_OP_RECONSTRUCT, 334 STRIPE_OP_CHECK, 335 }; 336 /* 337 * Plugging: 338 * 339 * To improve write throughput, we need to delay the handling of some 340 * stripes until there has been a chance that several write requests 341 * for the one stripe have all been collected. 342 * In particular, any write request that would require pre-reading 343 * is put on a "delayed" queue until there are no stripes currently 344 * in a pre-read phase. Further, if the "delayed" queue is empty when 345 * a stripe is put on it then we "plug" the queue and do not process it 346 * until an unplug call is made. (the unplug_io_fn() is called). 347 * 348 * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add 349 * it to the count of prereading stripes. 350 * When write is initiated, or the stripe refcnt == 0 (just in case) we 351 * clear the PREREAD_ACTIVE flag and decrement the count 352 * Whenever the 'handle' queue is empty and the device is not plugged, we 353 * move any strips from delayed to handle and clear the DELAYED flag and set 354 * PREREAD_ACTIVE. 355 * In stripe_handle, if we find pre-reading is necessary, we do it if 356 * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue. 357 * HANDLE gets cleared if stripe_handle leaves nothing locked. 358 */ 359 360 361 struct disk_info { 362 struct md_rdev *rdev, *replacement; 363 }; 364 365 struct r5conf { 366 struct hlist_head *stripe_hashtbl; 367 struct mddev *mddev; 368 int chunk_sectors; 369 int level, algorithm; 370 int max_degraded; 371 int raid_disks; 372 int max_nr_stripes; 373 374 /* reshape_progress is the leading edge of a 'reshape' 375 * It has value MaxSector when no reshape is happening 376 * If delta_disks < 0, it is the last sector we started work on, 377 * else is it the next sector to work on. 378 */ 379 sector_t reshape_progress; 380 /* reshape_safe is the trailing edge of a reshape. We know that 381 * before (or after) this address, all reshape has completed. 382 */ 383 sector_t reshape_safe; 384 int previous_raid_disks; 385 int prev_chunk_sectors; 386 int prev_algo; 387 short generation; /* increments with every reshape */ 388 unsigned long reshape_checkpoint; /* Time we last updated 389 * metadata */ 390 long long min_offset_diff; /* minimum difference between 391 * data_offset and 392 * new_data_offset across all 393 * devices. May be negative, 394 * but is closest to zero. 395 */ 396 397 struct list_head handle_list; /* stripes needing handling */ 398 struct list_head hold_list; /* preread ready stripes */ 399 struct list_head delayed_list; /* stripes that have plugged requests */ 400 struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */ 401 struct bio *retry_read_aligned; /* currently retrying aligned bios */ 402 struct bio *retry_read_aligned_list; /* aligned bios retry list */ 403 atomic_t preread_active_stripes; /* stripes with scheduled io */ 404 atomic_t active_aligned_reads; 405 atomic_t pending_full_writes; /* full write backlog */ 406 int bypass_count; /* bypassed prereads */ 407 int bypass_threshold; /* preread nice */ 408 struct list_head *last_hold; /* detect hold_list promotions */ 409 410 atomic_t reshape_stripes; /* stripes with pending writes for reshape */ 411 /* unfortunately we need two cache names as we temporarily have 412 * two caches. 413 */ 414 int active_name; 415 char cache_name[2][32]; 416 struct kmem_cache *slab_cache; /* for allocating stripes */ 417 418 int seq_flush, seq_write; 419 int quiesce; 420 421 int fullsync; /* set to 1 if a full sync is needed, 422 * (fresh device added). 423 * Cleared when a sync completes. 424 */ 425 int recovery_disabled; 426 /* per cpu variables */ 427 struct raid5_percpu { 428 struct page *spare_page; /* Used when checking P/Q in raid6 */ 429 void *scribble; /* space for constructing buffer 430 * lists and performing address 431 * conversions 432 */ 433 } __percpu *percpu; 434 size_t scribble_len; /* size of scribble region must be 435 * associated with conf to handle 436 * cpu hotplug while reshaping 437 */ 438 #ifdef CONFIG_HOTPLUG_CPU 439 struct notifier_block cpu_notify; 440 #endif 441 442 /* 443 * Free stripes pool 444 */ 445 atomic_t active_stripes; 446 struct list_head inactive_list; 447 wait_queue_head_t wait_for_stripe; 448 wait_queue_head_t wait_for_overlap; 449 int inactive_blocked; /* release of inactive stripes blocked, 450 * waiting for 25% to be free 451 */ 452 int pool_size; /* number of disks in stripeheads in pool */ 453 spinlock_t device_lock; 454 struct disk_info *disks; 455 456 /* When taking over an array from a different personality, we store 457 * the new thread here until we fully activate the array. 458 */ 459 struct md_thread *thread; 460 }; 461 462 /* 463 * Our supported algorithms 464 */ 465 #define ALGORITHM_LEFT_ASYMMETRIC 0 /* Rotating Parity N with Data Restart */ 466 #define ALGORITHM_RIGHT_ASYMMETRIC 1 /* Rotating Parity 0 with Data Restart */ 467 #define ALGORITHM_LEFT_SYMMETRIC 2 /* Rotating Parity N with Data Continuation */ 468 #define ALGORITHM_RIGHT_SYMMETRIC 3 /* Rotating Parity 0 with Data Continuation */ 469 470 /* Define non-rotating (raid4) algorithms. These allow 471 * conversion of raid4 to raid5. 472 */ 473 #define ALGORITHM_PARITY_0 4 /* P or P,Q are initial devices */ 474 #define ALGORITHM_PARITY_N 5 /* P or P,Q are final devices. */ 475 476 /* DDF RAID6 layouts differ from md/raid6 layouts in two ways. 477 * Firstly, the exact positioning of the parity block is slightly 478 * different between the 'LEFT_*' modes of md and the "_N_*" modes 479 * of DDF. 480 * Secondly, or order of datablocks over which the Q syndrome is computed 481 * is different. 482 * Consequently we have different layouts for DDF/raid6 than md/raid6. 483 * These layouts are from the DDFv1.2 spec. 484 * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but 485 * leaves RLQ=3 as 'Vendor Specific' 486 */ 487 488 #define ALGORITHM_ROTATING_ZERO_RESTART 8 /* DDF PRL=6 RLQ=1 */ 489 #define ALGORITHM_ROTATING_N_RESTART 9 /* DDF PRL=6 RLQ=2 */ 490 #define ALGORITHM_ROTATING_N_CONTINUE 10 /*DDF PRL=6 RLQ=3 */ 491 492 493 /* For every RAID5 algorithm we define a RAID6 algorithm 494 * with exactly the same layout for data and parity, and 495 * with the Q block always on the last device (N-1). 496 * This allows trivial conversion from RAID5 to RAID6 497 */ 498 #define ALGORITHM_LEFT_ASYMMETRIC_6 16 499 #define ALGORITHM_RIGHT_ASYMMETRIC_6 17 500 #define ALGORITHM_LEFT_SYMMETRIC_6 18 501 #define ALGORITHM_RIGHT_SYMMETRIC_6 19 502 #define ALGORITHM_PARITY_0_6 20 503 #define ALGORITHM_PARITY_N_6 ALGORITHM_PARITY_N 504 505 static inline int algorithm_valid_raid5(int layout) 506 { 507 return (layout >= 0) && 508 (layout <= 5); 509 } 510 static inline int algorithm_valid_raid6(int layout) 511 { 512 return (layout >= 0 && layout <= 5) 513 || 514 (layout >= 8 && layout <= 10) 515 || 516 (layout >= 16 && layout <= 20); 517 } 518 519 static inline int algorithm_is_DDF(int layout) 520 { 521 return layout >= 8 && layout <= 10; 522 } 523 524 extern int md_raid5_congested(struct mddev *mddev, int bits); 525 extern void md_raid5_kick_device(struct r5conf *conf); 526 extern int raid5_set_cache_size(struct mddev *mddev, int size); 527 #endif 528