| #ifndef _RAID5_H |
| #define _RAID5_H |
| |
| #include <linux/raid/xor.h> |
| #include <linux/dmaengine.h> |
| |
| /* |
| * |
| * Each stripe contains one buffer per device. Each buffer can be in |
| * one of a number of states stored in "flags". Changes between |
| * these states happen *almost* exclusively under the protection of the |
| * STRIPE_ACTIVE flag. Some very specific changes can happen in bi_end_io, and |
| * these are not protected by STRIPE_ACTIVE. |
| * |
| * The flag bits that are used to represent these states are: |
| * R5_UPTODATE and R5_LOCKED |
| * |
| * State Empty == !UPTODATE, !LOCK |
| * We have no data, and there is no active request |
| * State Want == !UPTODATE, LOCK |
| * A read request is being submitted for this block |
| * State Dirty == UPTODATE, LOCK |
| * Some new data is in this buffer, and it is being written out |
| * State Clean == UPTODATE, !LOCK |
| * We have valid data which is the same as on disc |
| * |
| * The possible state transitions are: |
| * |
| * Empty -> Want - on read or write to get old data for parity calc |
| * Empty -> Dirty - on compute_parity to satisfy write/sync request. |
| * Empty -> Clean - on compute_block when computing a block for failed drive |
| * Want -> Empty - on failed read |
| * Want -> Clean - on successful completion of read request |
| * Dirty -> Clean - on successful completion of write request |
| * Dirty -> Clean - on failed write |
| * Clean -> Dirty - on compute_parity to satisfy write/sync (RECONSTRUCT or RMW) |
| * |
| * The Want->Empty, Want->Clean, Dirty->Clean, transitions |
| * all happen in b_end_io at interrupt time. |
| * Each sets the Uptodate bit before releasing the Lock bit. |
| * This leaves one multi-stage transition: |
| * Want->Dirty->Clean |
| * This is safe because thinking that a Clean buffer is actually dirty |
| * will at worst delay some action, and the stripe will be scheduled |
| * for attention after the transition is complete. |
| * |
| * There is one possibility that is not covered by these states. That |
| * is if one drive has failed and there is a spare being rebuilt. We |
| * can't distinguish between a clean block that has been generated |
| * from parity calculations, and a clean block that has been |
| * successfully written to the spare ( or to parity when resyncing). |
| * To distinguish these states we have a stripe bit STRIPE_INSYNC that |
| * is set whenever a write is scheduled to the spare, or to the parity |
| * disc if there is no spare. A sync request clears this bit, and |
| * when we find it set with no buffers locked, we know the sync is |
| * complete. |
| * |
| * Buffers for the md device that arrive via make_request are attached |
| * to the appropriate stripe in one of two lists linked on b_reqnext. |
| * One list (bh_read) for read requests, one (bh_write) for write. |
| * There should never be more than one buffer on the two lists |
| * together, but we are not guaranteed of that so we allow for more. |
| * |
| * If a buffer is on the read list when the associated cache buffer is |
| * Uptodate, the data is copied into the read buffer and it's b_end_io |
| * routine is called. This may happen in the end_request routine only |
| * if the buffer has just successfully been read. end_request should |
| * remove the buffers from the list and then set the Uptodate bit on |
| * the buffer. Other threads may do this only if they first check |
| * that the Uptodate bit is set. Once they have checked that they may |
| * take buffers off the read queue. |
| * |
| * When a buffer on the write list is committed for write it is copied |
| * into the cache buffer, which is then marked dirty, and moved onto a |
| * third list, the written list (bh_written). Once both the parity |
| * block and the cached buffer are successfully written, any buffer on |
| * a written list can be returned with b_end_io. |
| * |
| * The write list and read list both act as fifos. The read list, |
| * write list and written list are protected by the device_lock. |
| * The device_lock is only for list manipulations and will only be |
| * held for a very short time. It can be claimed from interrupts. |
| * |
| * |
| * Stripes in the stripe cache can be on one of two lists (or on |
| * neither). The "inactive_list" contains stripes which are not |
| * currently being used for any request. They can freely be reused |
| * for another stripe. The "handle_list" contains stripes that need |
| * to be handled in some way. Both of these are fifo queues. Each |
| * stripe is also (potentially) linked to a hash bucket in the hash |
| * table so that it can be found by sector number. Stripes that are |
| * not hashed must be on the inactive_list, and will normally be at |
| * the front. All stripes start life this way. |
| * |
| * The inactive_list, handle_list and hash bucket lists are all protected by the |
| * device_lock. |
| * - stripes have a reference counter. If count==0, they are on a list. |
| * - If a stripe might need handling, STRIPE_HANDLE is set. |
| * - When refcount reaches zero, then if STRIPE_HANDLE it is put on |
| * handle_list else inactive_list |
| * |
| * This, combined with the fact that STRIPE_HANDLE is only ever |
| * cleared while a stripe has a non-zero count means that if the |
| * refcount is 0 and STRIPE_HANDLE is set, then it is on the |
| * handle_list and if recount is 0 and STRIPE_HANDLE is not set, then |
| * the stripe is on inactive_list. |
| * |
| * The possible transitions are: |
| * activate an unhashed/inactive stripe (get_active_stripe()) |
| * lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev |
| * activate a hashed, possibly active stripe (get_active_stripe()) |
| * lockdev check-hash if(!cnt++)unlink-stripe unlockdev |
| * attach a request to an active stripe (add_stripe_bh()) |
| * lockdev attach-buffer unlockdev |
| * handle a stripe (handle_stripe()) |
| * setSTRIPE_ACTIVE, clrSTRIPE_HANDLE ... |
| * (lockdev check-buffers unlockdev) .. |
| * change-state .. |
| * record io/ops needed clearSTRIPE_ACTIVE schedule io/ops |
| * release an active stripe (release_stripe()) |
| * lockdev if (!--cnt) { if STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev |
| * |
| * The refcount counts each thread that have activated the stripe, |
| * plus raid5d if it is handling it, plus one for each active request |
| * on a cached buffer, and plus one if the stripe is undergoing stripe |
| * operations. |
| * |
| * The stripe operations are: |
| * -copying data between the stripe cache and user application buffers |
| * -computing blocks to save a disk access, or to recover a missing block |
| * -updating the parity on a write operation (reconstruct write and |
| * read-modify-write) |
| * -checking parity correctness |
| * -running i/o to disk |
| * These operations are carried out by raid5_run_ops which uses the async_tx |
| * api to (optionally) offload operations to dedicated hardware engines. |
| * When requesting an operation handle_stripe sets the pending bit for the |
| * operation and increments the count. raid5_run_ops is then run whenever |
| * the count is non-zero. |
| * There are some critical dependencies between the operations that prevent some |
| * from being requested while another is in flight. |
| * 1/ Parity check operations destroy the in cache version of the parity block, |
| * so we prevent parity dependent operations like writes and compute_blocks |
| * from starting while a check is in progress. Some dma engines can perform |
| * the check without damaging the parity block, in these cases the parity |
| * block is re-marked up to date (assuming the check was successful) and is |
| * not re-read from disk. |
| * 2/ When a write operation is requested we immediately lock the affected |
| * blocks, and mark them as not up to date. This causes new read requests |
| * to be held off, as well as parity checks and compute block operations. |
| * 3/ Once a compute block operation has been requested handle_stripe treats |
| * that block as if it is up to date. raid5_run_ops guaruntees that any |
| * operation that is dependent on the compute block result is initiated after |
| * the compute block completes. |
| */ |
| |
| /* |
| * Operations state - intermediate states that are visible outside of |
| * STRIPE_ACTIVE. |
| * In general _idle indicates nothing is running, _run indicates a data |
| * processing operation is active, and _result means the data processing result |
| * is stable and can be acted upon. For simple operations like biofill and |
| * compute that only have an _idle and _run state they are indicated with |
| * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN) |
| */ |
| /** |
| * enum check_states - handles syncing / repairing a stripe |
| * @check_state_idle - check operations are quiesced |
| * @check_state_run - check operation is running |
| * @check_state_result - set outside lock when check result is valid |
| * @check_state_compute_run - check failed and we are repairing |
| * @check_state_compute_result - set outside lock when compute result is valid |
| */ |
| enum check_states { |
| check_state_idle = 0, |
| check_state_run, /* xor parity check */ |
| check_state_run_q, /* q-parity check */ |
| check_state_run_pq, /* pq dual parity check */ |
| check_state_check_result, |
| check_state_compute_run, /* parity repair */ |
| check_state_compute_result, |
| }; |
| |
| /** |
| * enum reconstruct_states - handles writing or expanding a stripe |
| */ |
| enum reconstruct_states { |
| reconstruct_state_idle = 0, |
| reconstruct_state_prexor_drain_run, /* prexor-write */ |
| reconstruct_state_drain_run, /* write */ |
| reconstruct_state_run, /* expand */ |
| reconstruct_state_prexor_drain_result, |
| reconstruct_state_drain_result, |
| reconstruct_state_result, |
| }; |
| |
| struct stripe_head { |
| struct hlist_node hash; |
| struct list_head lru; /* inactive_list or handle_list */ |
| struct llist_node release_list; |
| struct r5conf *raid_conf; |
| short generation; /* increments with every |
| * reshape */ |
| sector_t sector; /* sector of this row */ |
| short pd_idx; /* parity disk index */ |
| short qd_idx; /* 'Q' disk index for raid6 */ |
| short ddf_layout;/* use DDF ordering to calculate Q */ |
| short hash_lock_index; |
| unsigned long state; /* state flags */ |
| atomic_t count; /* nr of active thread/requests */ |
| int bm_seq; /* sequence number for bitmap flushes */ |
| int disks; /* disks in stripe */ |
| int overwrite_disks; /* total overwrite disks in stripe, |
| * this is only checked when stripe |
| * has STRIPE_BATCH_READY |
| */ |
| enum check_states check_state; |
| enum reconstruct_states reconstruct_state; |
| spinlock_t stripe_lock; |
| int cpu; |
| struct r5worker_group *group; |
| |
| struct stripe_head *batch_head; /* protected by stripe lock */ |
| spinlock_t batch_lock; /* only header's lock is useful */ |
| struct list_head batch_list; /* protected by head's batch lock*/ |
| /** |
| * struct stripe_operations |
| * @target - STRIPE_OP_COMPUTE_BLK target |
| * @target2 - 2nd compute target in the raid6 case |
| * @zero_sum_result - P and Q verification flags |
| * @request - async service request flags for raid_run_ops |
| */ |
| struct stripe_operations { |
| int target, target2; |
| enum sum_check_flags zero_sum_result; |
| } ops; |
| struct r5dev { |
| /* rreq and rvec are used for the replacement device when |
| * writing data to both devices. |
| */ |
| struct bio req, rreq; |
| struct bio_vec vec, rvec; |
| struct page *page, *orig_page; |
| struct bio *toread, *read, *towrite, *written; |
| sector_t sector; /* sector of this page */ |
| unsigned long flags; |
| } dev[1]; /* allocated with extra space depending of RAID geometry */ |
| }; |
| |
| /* stripe_head_state - collects and tracks the dynamic state of a stripe_head |
| * for handle_stripe. |
| */ |
| struct stripe_head_state { |
| /* 'syncing' means that we need to read all devices, either |
| * to check/correct parity, or to reconstruct a missing device. |
| * 'replacing' means we are replacing one or more drives and |
| * the source is valid at this point so we don't need to |
| * read all devices, just the replacement targets. |
| */ |
| int syncing, expanding, expanded, replacing; |
| int locked, uptodate, to_read, to_write, failed, written; |
| int to_fill, compute, req_compute, non_overwrite; |
| int failed_num[2]; |
| int p_failed, q_failed; |
| int dec_preread_active; |
| unsigned long ops_request; |
| |
| struct bio *return_bi; |
| struct md_rdev *blocked_rdev; |
| int handle_bad_blocks; |
| }; |
| |
| /* Flags for struct r5dev.flags */ |
| enum r5dev_flags { |
| R5_UPTODATE, /* page contains current data */ |
| R5_LOCKED, /* IO has been submitted on "req" */ |
| R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */ |
| R5_OVERWRITE, /* towrite covers whole page */ |
| /* and some that are internal to handle_stripe */ |
| R5_Insync, /* rdev && rdev->in_sync at start */ |
| R5_Wantread, /* want to schedule a read */ |
| R5_Wantwrite, |
| R5_Overlap, /* There is a pending overlapping request |
| * on this block */ |
| R5_ReadNoMerge, /* prevent bio from merging in block-layer */ |
| R5_ReadError, /* seen a read error here recently */ |
| R5_ReWrite, /* have tried to over-write the readerror */ |
| |
| R5_Expanded, /* This block now has post-expand data */ |
| R5_Wantcompute, /* compute_block in progress treat as |
| * uptodate |
| */ |
| R5_Wantfill, /* dev->toread contains a bio that needs |
| * filling |
| */ |
| R5_Wantdrain, /* dev->towrite needs to be drained */ |
| R5_WantFUA, /* Write should be FUA */ |
| R5_SyncIO, /* The IO is sync */ |
| R5_WriteError, /* got a write error - need to record it */ |
| R5_MadeGood, /* A bad block has been fixed by writing to it */ |
| R5_ReadRepl, /* Will/did read from replacement rather than orig */ |
| R5_MadeGoodRepl,/* A bad block on the replacement device has been |
| * fixed by writing to it */ |
| R5_NeedReplace, /* This device has a replacement which is not |
| * up-to-date at this stripe. */ |
| R5_WantReplace, /* We need to update the replacement, we have read |
| * data in, and now is a good time to write it out. |
| */ |
| R5_Discard, /* Discard the stripe */ |
| R5_SkipCopy, /* Don't copy data from bio to stripe cache */ |
| }; |
| |
| /* |
| * Stripe state |
| */ |
| enum { |
| STRIPE_ACTIVE, |
| STRIPE_HANDLE, |
| STRIPE_SYNC_REQUESTED, |
| STRIPE_SYNCING, |
| STRIPE_INSYNC, |
| STRIPE_REPLACED, |
| STRIPE_PREREAD_ACTIVE, |
| STRIPE_DELAYED, |
| STRIPE_DEGRADED, |
| STRIPE_BIT_DELAY, |
| STRIPE_EXPANDING, |
| STRIPE_EXPAND_SOURCE, |
| STRIPE_EXPAND_READY, |
| STRIPE_IO_STARTED, /* do not count towards 'bypass_count' */ |
| STRIPE_FULL_WRITE, /* all blocks are set to be overwritten */ |
| STRIPE_BIOFILL_RUN, |
| STRIPE_COMPUTE_RUN, |
| STRIPE_OPS_REQ_PENDING, |
| STRIPE_ON_UNPLUG_LIST, |
| STRIPE_DISCARD, |
| STRIPE_ON_RELEASE_LIST, |
| STRIPE_BATCH_READY, |
| STRIPE_BATCH_ERR, |
| STRIPE_BITMAP_PENDING, /* Being added to bitmap, don't add |
| * to batch yet. |
| */ |
| }; |
| |
| #define STRIPE_EXPAND_SYNC_FLAGS \ |
| ((1 << STRIPE_EXPAND_SOURCE) |\ |
| (1 << STRIPE_EXPAND_READY) |\ |
| (1 << STRIPE_EXPANDING) |\ |
| (1 << STRIPE_SYNC_REQUESTED)) |
| /* |
| * Operation request flags |
| */ |
| enum { |
| STRIPE_OP_BIOFILL, |
| STRIPE_OP_COMPUTE_BLK, |
| STRIPE_OP_PREXOR, |
| STRIPE_OP_BIODRAIN, |
| STRIPE_OP_RECONSTRUCT, |
| STRIPE_OP_CHECK, |
| }; |
| |
| /* |
| * RAID parity calculation preferences |
| */ |
| enum { |
| PARITY_DISABLE_RMW = 0, |
| PARITY_ENABLE_RMW, |
| PARITY_PREFER_RMW, |
| }; |
| |
| /* |
| * Pages requested from set_syndrome_sources() |
| */ |
| enum { |
| SYNDROME_SRC_ALL, |
| SYNDROME_SRC_WANT_DRAIN, |
| SYNDROME_SRC_WRITTEN, |
| }; |
| /* |
| * Plugging: |
| * |
| * To improve write throughput, we need to delay the handling of some |
| * stripes until there has been a chance that several write requests |
| * for the one stripe have all been collected. |
| * In particular, any write request that would require pre-reading |
| * is put on a "delayed" queue until there are no stripes currently |
| * in a pre-read phase. Further, if the "delayed" queue is empty when |
| * a stripe is put on it then we "plug" the queue and do not process it |
| * until an unplug call is made. (the unplug_io_fn() is called). |
| * |
| * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add |
| * it to the count of prereading stripes. |
| * When write is initiated, or the stripe refcnt == 0 (just in case) we |
| * clear the PREREAD_ACTIVE flag and decrement the count |
| * Whenever the 'handle' queue is empty and the device is not plugged, we |
| * move any strips from delayed to handle and clear the DELAYED flag and set |
| * PREREAD_ACTIVE. |
| * In stripe_handle, if we find pre-reading is necessary, we do it if |
| * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue. |
| * HANDLE gets cleared if stripe_handle leaves nothing locked. |
| */ |
| |
| struct disk_info { |
| struct md_rdev *rdev, *replacement; |
| }; |
| |
| /* NOTE NR_STRIPE_HASH_LOCKS must remain below 64. |
| * This is because we sometimes take all the spinlocks |
| * and creating that much locking depth can cause |
| * problems. |
| */ |
| #define NR_STRIPE_HASH_LOCKS 8 |
| #define STRIPE_HASH_LOCKS_MASK (NR_STRIPE_HASH_LOCKS - 1) |
| |
| struct r5worker { |
| struct work_struct work; |
| struct r5worker_group *group; |
| struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS]; |
| bool working; |
| }; |
| |
| struct r5worker_group { |
| struct list_head handle_list; |
| struct r5conf *conf; |
| struct r5worker *workers; |
| int stripes_cnt; |
| }; |
| |
| struct r5conf { |
| struct hlist_head *stripe_hashtbl; |
| /* only protect corresponding hash list and inactive_list */ |
| spinlock_t hash_locks[NR_STRIPE_HASH_LOCKS]; |
| struct mddev *mddev; |
| int chunk_sectors; |
| int level, algorithm, rmw_level; |
| int max_degraded; |
| int raid_disks; |
| int max_nr_stripes; |
| int min_nr_stripes; |
| |
| /* reshape_progress is the leading edge of a 'reshape' |
| * It has value MaxSector when no reshape is happening |
| * If delta_disks < 0, it is the last sector we started work on, |
| * else is it the next sector to work on. |
| */ |
| sector_t reshape_progress; |
| /* reshape_safe is the trailing edge of a reshape. We know that |
| * before (or after) this address, all reshape has completed. |
| */ |
| sector_t reshape_safe; |
| int previous_raid_disks; |
| int prev_chunk_sectors; |
| int prev_algo; |
| short generation; /* increments with every reshape */ |
| seqcount_t gen_lock; /* lock against generation changes */ |
| unsigned long reshape_checkpoint; /* Time we last updated |
| * metadata */ |
| long long min_offset_diff; /* minimum difference between |
| * data_offset and |
| * new_data_offset across all |
| * devices. May be negative, |
| * but is closest to zero. |
| */ |
| |
| struct list_head handle_list; /* stripes needing handling */ |
| struct list_head hold_list; /* preread ready stripes */ |
| struct list_head delayed_list; /* stripes that have plugged requests */ |
| struct list_head bitmap_list; /* stripes delaying awaiting bitmap update */ |
| struct bio *retry_read_aligned; /* currently retrying aligned bios */ |
| struct bio *retry_read_aligned_list; /* aligned bios retry list */ |
| atomic_t preread_active_stripes; /* stripes with scheduled io */ |
| atomic_t active_aligned_reads; |
| atomic_t pending_full_writes; /* full write backlog */ |
| int bypass_count; /* bypassed prereads */ |
| int bypass_threshold; /* preread nice */ |
| int skip_copy; /* Don't copy data from bio to stripe cache */ |
| struct list_head *last_hold; /* detect hold_list promotions */ |
| |
| atomic_t reshape_stripes; /* stripes with pending writes for reshape */ |
| /* unfortunately we need two cache names as we temporarily have |
| * two caches. |
| */ |
| int active_name; |
| char cache_name[2][32]; |
| struct kmem_cache *slab_cache; /* for allocating stripes */ |
| struct mutex cache_size_mutex; /* Protect changes to cache size */ |
| |
| int seq_flush, seq_write; |
| int quiesce; |
| |
| int fullsync; /* set to 1 if a full sync is needed, |
| * (fresh device added). |
| * Cleared when a sync completes. |
| */ |
| int recovery_disabled; |
| /* per cpu variables */ |
| struct raid5_percpu { |
| struct page *spare_page; /* Used when checking P/Q in raid6 */ |
| struct flex_array *scribble; /* space for constructing buffer |
| * lists and performing address |
| * conversions |
| */ |
| } __percpu *percpu; |
| #ifdef CONFIG_HOTPLUG_CPU |
| struct notifier_block cpu_notify; |
| #endif |
| |
| /* |
| * Free stripes pool |
| */ |
| atomic_t active_stripes; |
| struct list_head inactive_list[NR_STRIPE_HASH_LOCKS]; |
| atomic_t empty_inactive_list_nr; |
| struct llist_head released_stripes; |
| wait_queue_head_t wait_for_stripe; |
| wait_queue_head_t wait_for_overlap; |
| unsigned long cache_state; |
| #define R5_INACTIVE_BLOCKED 1 /* release of inactive stripes blocked, |
| * waiting for 25% to be free |
| */ |
| #define R5_ALLOC_MORE 2 /* It might help to allocate another |
| * stripe. |
| */ |
| #define R5_DID_ALLOC 4 /* A stripe was allocated, don't allocate |
| * more until at least one has been |
| * released. This avoids flooding |
| * the cache. |
| */ |
| struct shrinker shrinker; |
| int pool_size; /* number of disks in stripeheads in pool */ |
| spinlock_t device_lock; |
| struct disk_info *disks; |
| |
| /* When taking over an array from a different personality, we store |
| * the new thread here until we fully activate the array. |
| */ |
| struct md_thread *thread; |
| struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS]; |
| struct r5worker_group *worker_groups; |
| int group_cnt; |
| int worker_cnt_per_group; |
| }; |
| |
| |
| /* |
| * Our supported algorithms |
| */ |
| #define ALGORITHM_LEFT_ASYMMETRIC 0 /* Rotating Parity N with Data Restart */ |
| #define ALGORITHM_RIGHT_ASYMMETRIC 1 /* Rotating Parity 0 with Data Restart */ |
| #define ALGORITHM_LEFT_SYMMETRIC 2 /* Rotating Parity N with Data Continuation */ |
| #define ALGORITHM_RIGHT_SYMMETRIC 3 /* Rotating Parity 0 with Data Continuation */ |
| |
| /* Define non-rotating (raid4) algorithms. These allow |
| * conversion of raid4 to raid5. |
| */ |
| #define ALGORITHM_PARITY_0 4 /* P or P,Q are initial devices */ |
| #define ALGORITHM_PARITY_N 5 /* P or P,Q are final devices. */ |
| |
| /* DDF RAID6 layouts differ from md/raid6 layouts in two ways. |
| * Firstly, the exact positioning of the parity block is slightly |
| * different between the 'LEFT_*' modes of md and the "_N_*" modes |
| * of DDF. |
| * Secondly, or order of datablocks over which the Q syndrome is computed |
| * is different. |
| * Consequently we have different layouts for DDF/raid6 than md/raid6. |
| * These layouts are from the DDFv1.2 spec. |
| * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but |
| * leaves RLQ=3 as 'Vendor Specific' |
| */ |
| |
| #define ALGORITHM_ROTATING_ZERO_RESTART 8 /* DDF PRL=6 RLQ=1 */ |
| #define ALGORITHM_ROTATING_N_RESTART 9 /* DDF PRL=6 RLQ=2 */ |
| #define ALGORITHM_ROTATING_N_CONTINUE 10 /*DDF PRL=6 RLQ=3 */ |
| |
| /* For every RAID5 algorithm we define a RAID6 algorithm |
| * with exactly the same layout for data and parity, and |
| * with the Q block always on the last device (N-1). |
| * This allows trivial conversion from RAID5 to RAID6 |
| */ |
| #define ALGORITHM_LEFT_ASYMMETRIC_6 16 |
| #define ALGORITHM_RIGHT_ASYMMETRIC_6 17 |
| #define ALGORITHM_LEFT_SYMMETRIC_6 18 |
| #define ALGORITHM_RIGHT_SYMMETRIC_6 19 |
| #define ALGORITHM_PARITY_0_6 20 |
| #define ALGORITHM_PARITY_N_6 ALGORITHM_PARITY_N |
| |
| static inline int algorithm_valid_raid5(int layout) |
| { |
| return (layout >= 0) && |
| (layout <= 5); |
| } |
| static inline int algorithm_valid_raid6(int layout) |
| { |
| return (layout >= 0 && layout <= 5) |
| || |
| (layout >= 8 && layout <= 10) |
| || |
| (layout >= 16 && layout <= 20); |
| } |
| |
| static inline int algorithm_is_DDF(int layout) |
| { |
| return layout >= 8 && layout <= 10; |
| } |
| |
| extern void md_raid5_kick_device(struct r5conf *conf); |
| extern int raid5_set_cache_size(struct mddev *mddev, int size); |
| #endif |