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 distinguish 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 llist_node release_list; 201 struct r5conf *raid_conf; 202 short generation; /* increments with every 203 * reshape */ 204 sector_t sector; /* sector of this row */ 205 short pd_idx; /* parity disk index */ 206 short qd_idx; /* 'Q' disk index for raid6 */ 207 short ddf_layout;/* use DDF ordering to calculate Q */ 208 short hash_lock_index; 209 unsigned long state; /* state flags */ 210 atomic_t count; /* nr of active thread/requests */ 211 int bm_seq; /* sequence number for bitmap flushes */ 212 int disks; /* disks in stripe */ 213 int overwrite_disks; /* total overwrite disks in stripe, 214 * this is only checked when stripe 215 * has STRIPE_BATCH_READY 216 */ 217 enum check_states check_state; 218 enum reconstruct_states reconstruct_state; 219 spinlock_t stripe_lock; 220 int cpu; 221 struct r5worker_group *group; 222 223 struct stripe_head *batch_head; /* protected by stripe lock */ 224 spinlock_t batch_lock; /* only header's lock is useful */ 225 struct list_head batch_list; /* protected by head's batch lock*/ 226 /** 227 * struct stripe_operations 228 * @target - STRIPE_OP_COMPUTE_BLK target 229 * @target2 - 2nd compute target in the raid6 case 230 * @zero_sum_result - P and Q verification flags 231 * @request - async service request flags for raid_run_ops 232 */ 233 struct stripe_operations { 234 int target, target2; 235 enum sum_check_flags zero_sum_result; 236 } ops; 237 struct r5dev { 238 /* rreq and rvec are used for the replacement device when 239 * writing data to both devices. 240 */ 241 struct bio req, rreq; 242 struct bio_vec vec, rvec; 243 struct page *page, *orig_page; 244 struct bio *toread, *read, *towrite, *written; 245 sector_t sector; /* sector of this page */ 246 unsigned long flags; 247 } dev[1]; /* allocated with extra space depending of RAID geometry */ 248 }; 249 250 /* stripe_head_state - collects and tracks the dynamic state of a stripe_head 251 * for handle_stripe. 252 */ 253 struct stripe_head_state { 254 /* 'syncing' means that we need to read all devices, either 255 * to check/correct parity, or to reconstruct a missing device. 256 * 'replacing' means we are replacing one or more drives and 257 * the source is valid at this point so we don't need to 258 * read all devices, just the replacement targets. 259 */ 260 int syncing, expanding, expanded, replacing; 261 int locked, uptodate, to_read, to_write, failed, written; 262 int to_fill, compute, req_compute, non_overwrite; 263 int failed_num[2]; 264 int p_failed, q_failed; 265 int dec_preread_active; 266 unsigned long ops_request; 267 268 struct bio_list return_bi; 269 struct md_rdev *blocked_rdev; 270 int handle_bad_blocks; 271 }; 272 273 /* Flags for struct r5dev.flags */ 274 enum r5dev_flags { 275 R5_UPTODATE, /* page contains current data */ 276 R5_LOCKED, /* IO has been submitted on "req" */ 277 R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */ 278 R5_OVERWRITE, /* towrite covers whole page */ 279 /* and some that are internal to handle_stripe */ 280 R5_Insync, /* rdev && rdev->in_sync at start */ 281 R5_Wantread, /* want to schedule a read */ 282 R5_Wantwrite, 283 R5_Overlap, /* There is a pending overlapping request 284 * on this block */ 285 R5_ReadNoMerge, /* prevent bio from merging in block-layer */ 286 R5_ReadError, /* seen a read error here recently */ 287 R5_ReWrite, /* have tried to over-write the readerror */ 288 289 R5_Expanded, /* This block now has post-expand data */ 290 R5_Wantcompute, /* compute_block in progress treat as 291 * uptodate 292 */ 293 R5_Wantfill, /* dev->toread contains a bio that needs 294 * filling 295 */ 296 R5_Wantdrain, /* dev->towrite needs to be drained */ 297 R5_WantFUA, /* Write should be FUA */ 298 R5_SyncIO, /* The IO is sync */ 299 R5_WriteError, /* got a write error - need to record it */ 300 R5_MadeGood, /* A bad block has been fixed by writing to it */ 301 R5_ReadRepl, /* Will/did read from replacement rather than orig */ 302 R5_MadeGoodRepl,/* A bad block on the replacement device has been 303 * fixed by writing to it */ 304 R5_NeedReplace, /* This device has a replacement which is not 305 * up-to-date at this stripe. */ 306 R5_WantReplace, /* We need to update the replacement, we have read 307 * data in, and now is a good time to write it out. 308 */ 309 R5_Discard, /* Discard the stripe */ 310 R5_SkipCopy, /* Don't copy data from bio to stripe cache */ 311 }; 312 313 /* 314 * Stripe state 315 */ 316 enum { 317 STRIPE_ACTIVE, 318 STRIPE_HANDLE, 319 STRIPE_SYNC_REQUESTED, 320 STRIPE_SYNCING, 321 STRIPE_INSYNC, 322 STRIPE_REPLACED, 323 STRIPE_PREREAD_ACTIVE, 324 STRIPE_DELAYED, 325 STRIPE_DEGRADED, 326 STRIPE_BIT_DELAY, 327 STRIPE_EXPANDING, 328 STRIPE_EXPAND_SOURCE, 329 STRIPE_EXPAND_READY, 330 STRIPE_IO_STARTED, /* do not count towards 'bypass_count' */ 331 STRIPE_FULL_WRITE, /* all blocks are set to be overwritten */ 332 STRIPE_BIOFILL_RUN, 333 STRIPE_COMPUTE_RUN, 334 STRIPE_OPS_REQ_PENDING, 335 STRIPE_ON_UNPLUG_LIST, 336 STRIPE_DISCARD, 337 STRIPE_ON_RELEASE_LIST, 338 STRIPE_BATCH_READY, 339 STRIPE_BATCH_ERR, 340 STRIPE_BITMAP_PENDING, /* Being added to bitmap, don't add 341 * to batch yet. 342 */ 343 }; 344 345 #define STRIPE_EXPAND_SYNC_FLAGS \ 346 ((1 << STRIPE_EXPAND_SOURCE) |\ 347 (1 << STRIPE_EXPAND_READY) |\ 348 (1 << STRIPE_EXPANDING) |\ 349 (1 << STRIPE_SYNC_REQUESTED)) 350 /* 351 * Operation request flags 352 */ 353 enum { 354 STRIPE_OP_BIOFILL, 355 STRIPE_OP_COMPUTE_BLK, 356 STRIPE_OP_PREXOR, 357 STRIPE_OP_BIODRAIN, 358 STRIPE_OP_RECONSTRUCT, 359 STRIPE_OP_CHECK, 360 }; 361 362 /* 363 * RAID parity calculation preferences 364 */ 365 enum { 366 PARITY_DISABLE_RMW = 0, 367 PARITY_ENABLE_RMW, 368 PARITY_PREFER_RMW, 369 }; 370 371 /* 372 * Pages requested from set_syndrome_sources() 373 */ 374 enum { 375 SYNDROME_SRC_ALL, 376 SYNDROME_SRC_WANT_DRAIN, 377 SYNDROME_SRC_WRITTEN, 378 }; 379 /* 380 * Plugging: 381 * 382 * To improve write throughput, we need to delay the handling of some 383 * stripes until there has been a chance that several write requests 384 * for the one stripe have all been collected. 385 * In particular, any write request that would require pre-reading 386 * is put on a "delayed" queue until there are no stripes currently 387 * in a pre-read phase. Further, if the "delayed" queue is empty when 388 * a stripe is put on it then we "plug" the queue and do not process it 389 * until an unplug call is made. (the unplug_io_fn() is called). 390 * 391 * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add 392 * it to the count of prereading stripes. 393 * When write is initiated, or the stripe refcnt == 0 (just in case) we 394 * clear the PREREAD_ACTIVE flag and decrement the count 395 * Whenever the 'handle' queue is empty and the device is not plugged, we 396 * move any strips from delayed to handle and clear the DELAYED flag and set 397 * PREREAD_ACTIVE. 398 * In stripe_handle, if we find pre-reading is necessary, we do it if 399 * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue. 400 * HANDLE gets cleared if stripe_handle leaves nothing locked. 401 */ 402 403 struct disk_info { 404 struct md_rdev *rdev, *replacement; 405 }; 406 407 /* NOTE NR_STRIPE_HASH_LOCKS must remain below 64. 408 * This is because we sometimes take all the spinlocks 409 * and creating that much locking depth can cause 410 * problems. 411 */ 412 #define NR_STRIPE_HASH_LOCKS 8 413 #define STRIPE_HASH_LOCKS_MASK (NR_STRIPE_HASH_LOCKS - 1) 414 415 struct r5worker { 416 struct work_struct work; 417 struct r5worker_group *group; 418 struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS]; 419 bool working; 420 }; 421 422 struct r5worker_group { 423 struct list_head handle_list; 424 struct r5conf *conf; 425 struct r5worker *workers; 426 int stripes_cnt; 427 }; 428 429 struct r5conf { 430 struct hlist_head *stripe_hashtbl; 431 /* only protect corresponding hash list and inactive_list */ 432 spinlock_t hash_locks[NR_STRIPE_HASH_LOCKS]; 433 struct mddev *mddev; 434 int chunk_sectors; 435 int level, algorithm, rmw_level; 436 int max_degraded; 437 int raid_disks; 438 int max_nr_stripes; 439 int min_nr_stripes; 440 441 /* reshape_progress is the leading edge of a 'reshape' 442 * It has value MaxSector when no reshape is happening 443 * If delta_disks < 0, it is the last sector we started work on, 444 * else is it the next sector to work on. 445 */ 446 sector_t reshape_progress; 447 /* reshape_safe is the trailing edge of a reshape. We know that 448 * before (or after) this address, all reshape has completed. 449 */ 450 sector_t reshape_safe; 451 int previous_raid_disks; 452 int prev_chunk_sectors; 453 int prev_algo; 454 short generation; /* increments with every reshape */ 455 seqcount_t gen_lock; /* lock against generation changes */ 456 unsigned long reshape_checkpoint; /* Time we last updated 457 * metadata */ 458 long long min_offset_diff; /* minimum difference between 459 * data_offset and 460 * new_data_offset across all 461 * devices. May be negative, 462 * but is closest to zero. 463 */ 464 465 struct list_head handle_list; /* stripes needing handling */ 466 struct list_head hold_list; /* preread ready stripes */ 467 struct list_head delayed_list; /* stripes that have plugged requests */ 468 struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */ 469 struct bio *retry_read_aligned; /* currently retrying aligned bios */ 470 struct bio *retry_read_aligned_list; /* aligned bios retry list */ 471 atomic_t preread_active_stripes; /* stripes with scheduled io */ 472 atomic_t active_aligned_reads; 473 atomic_t pending_full_writes; /* full write backlog */ 474 int bypass_count; /* bypassed prereads */ 475 int bypass_threshold; /* preread nice */ 476 int skip_copy; /* Don't copy data from bio to stripe cache */ 477 struct list_head *last_hold; /* detect hold_list promotions */ 478 479 /* bios to have bi_end_io called after metadata is synced */ 480 struct bio_list return_bi; 481 482 atomic_t reshape_stripes; /* stripes with pending writes for reshape */ 483 /* unfortunately we need two cache names as we temporarily have 484 * two caches. 485 */ 486 int active_name; 487 char cache_name[2][32]; 488 struct kmem_cache *slab_cache; /* for allocating stripes */ 489 struct mutex cache_size_mutex; /* Protect changes to cache size */ 490 491 int seq_flush, seq_write; 492 int quiesce; 493 494 int fullsync; /* set to 1 if a full sync is needed, 495 * (fresh device added). 496 * Cleared when a sync completes. 497 */ 498 int recovery_disabled; 499 /* per cpu variables */ 500 struct raid5_percpu { 501 struct page *spare_page; /* Used when checking P/Q in raid6 */ 502 struct flex_array *scribble; /* space for constructing buffer 503 * lists and performing address 504 * conversions 505 */ 506 } __percpu *percpu; 507 #ifdef CONFIG_HOTPLUG_CPU 508 struct notifier_block cpu_notify; 509 #endif 510 511 /* 512 * Free stripes pool 513 */ 514 atomic_t active_stripes; 515 struct list_head inactive_list[NR_STRIPE_HASH_LOCKS]; 516 atomic_t empty_inactive_list_nr; 517 struct llist_head released_stripes; 518 wait_queue_head_t wait_for_quiescent; 519 wait_queue_head_t wait_for_stripe[NR_STRIPE_HASH_LOCKS]; 520 wait_queue_head_t wait_for_overlap; 521 unsigned long cache_state; 522 #define R5_INACTIVE_BLOCKED 1 /* release of inactive stripes blocked, 523 * waiting for 25% to be free 524 */ 525 #define R5_ALLOC_MORE 2 /* It might help to allocate another 526 * stripe. 527 */ 528 #define R5_DID_ALLOC 4 /* A stripe was allocated, don't allocate 529 * more until at least one has been 530 * released. This avoids flooding 531 * the cache. 532 */ 533 struct shrinker shrinker; 534 int pool_size; /* number of disks in stripeheads in pool */ 535 spinlock_t device_lock; 536 struct disk_info *disks; 537 538 /* When taking over an array from a different personality, we store 539 * the new thread here until we fully activate the array. 540 */ 541 struct md_thread *thread; 542 struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS]; 543 struct r5worker_group *worker_groups; 544 int group_cnt; 545 int worker_cnt_per_group; 546 }; 547 548 549 /* 550 * Our supported algorithms 551 */ 552 #define ALGORITHM_LEFT_ASYMMETRIC 0 /* Rotating Parity N with Data Restart */ 553 #define ALGORITHM_RIGHT_ASYMMETRIC 1 /* Rotating Parity 0 with Data Restart */ 554 #define ALGORITHM_LEFT_SYMMETRIC 2 /* Rotating Parity N with Data Continuation */ 555 #define ALGORITHM_RIGHT_SYMMETRIC 3 /* Rotating Parity 0 with Data Continuation */ 556 557 /* Define non-rotating (raid4) algorithms. These allow 558 * conversion of raid4 to raid5. 559 */ 560 #define ALGORITHM_PARITY_0 4 /* P or P,Q are initial devices */ 561 #define ALGORITHM_PARITY_N 5 /* P or P,Q are final devices. */ 562 563 /* DDF RAID6 layouts differ from md/raid6 layouts in two ways. 564 * Firstly, the exact positioning of the parity block is slightly 565 * different between the 'LEFT_*' modes of md and the "_N_*" modes 566 * of DDF. 567 * Secondly, or order of datablocks over which the Q syndrome is computed 568 * is different. 569 * Consequently we have different layouts for DDF/raid6 than md/raid6. 570 * These layouts are from the DDFv1.2 spec. 571 * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but 572 * leaves RLQ=3 as 'Vendor Specific' 573 */ 574 575 #define ALGORITHM_ROTATING_ZERO_RESTART 8 /* DDF PRL=6 RLQ=1 */ 576 #define ALGORITHM_ROTATING_N_RESTART 9 /* DDF PRL=6 RLQ=2 */ 577 #define ALGORITHM_ROTATING_N_CONTINUE 10 /*DDF PRL=6 RLQ=3 */ 578 579 /* For every RAID5 algorithm we define a RAID6 algorithm 580 * with exactly the same layout for data and parity, and 581 * with the Q block always on the last device (N-1). 582 * This allows trivial conversion from RAID5 to RAID6 583 */ 584 #define ALGORITHM_LEFT_ASYMMETRIC_6 16 585 #define ALGORITHM_RIGHT_ASYMMETRIC_6 17 586 #define ALGORITHM_LEFT_SYMMETRIC_6 18 587 #define ALGORITHM_RIGHT_SYMMETRIC_6 19 588 #define ALGORITHM_PARITY_0_6 20 589 #define ALGORITHM_PARITY_N_6 ALGORITHM_PARITY_N 590 591 static inline int algorithm_valid_raid5(int layout) 592 { 593 return (layout >= 0) && 594 (layout <= 5); 595 } 596 static inline int algorithm_valid_raid6(int layout) 597 { 598 return (layout >= 0 && layout <= 5) 599 || 600 (layout >= 8 && layout <= 10) 601 || 602 (layout >= 16 && layout <= 20); 603 } 604 605 static inline int algorithm_is_DDF(int layout) 606 { 607 return layout >= 8 && layout <= 10; 608 } 609 610 extern void md_raid5_kick_device(struct r5conf *conf); 611 extern int raid5_set_cache_size(struct mddev *mddev, int size); 612 #endif 613