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Diffstat (limited to 'include/linux/raid/raid5.h')
| -rw-r--r-- | include/linux/raid/raid5.h | 402 |
1 files changed, 0 insertions, 402 deletions
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h deleted file mode 100644 index 3b267279245..00000000000 --- a/include/linux/raid/raid5.h +++ /dev/null @@ -1,402 +0,0 @@ -#ifndef _RAID5_H -#define _RAID5_H - -#include <linux/raid/md.h> -#include <linux/raid/xor.h> - -/* - * - * Each stripe contains one buffer per disc. Each buffer can be in - * one of a number of states stored in "flags". Changes between - * these states happen *almost* exclusively under a per-stripe - * spinlock. Some very specific changes can happen in bi_end_io, and - * these are not protected by the spin lock. - * - * 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.(RECONSTRUCT_WRITE) - * 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 distingush 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 is - * protected by the device_lock. The write and written lists are - * protected by the stripe lock. The device_lock, which can be - * claimed while the stipe lock is held, 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 on the inactive_list never have their stripe_lock held. - * - 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()) - * lockstripe clrSTRIPE_HANDLE ... - * (lockdev check-buffers unlockdev) .. - * change-state .. - * record io/ops needed unlockstripe 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. - * - * Stripe operations are performed outside the stripe lock, - * 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 sh->lock - * 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, /* 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 raid5_private_data *raid_conf; - sector_t sector; /* sector of this row */ - int pd_idx; /* parity disk index */ - unsigned long state; /* state flags */ - atomic_t count; /* nr of active thread/requests */ - spinlock_t lock; - int bm_seq; /* sequence number for bitmap flushes */ - int disks; /* disks in stripe */ - enum check_states check_state; - enum reconstruct_states reconstruct_state; - /* stripe_operations - * @target - STRIPE_OP_COMPUTE_BLK target - */ - struct stripe_operations { - int target; - u32 zero_sum_result; - } ops; - struct r5dev { - struct bio req; - struct bio_vec vec; - struct page *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. It is only valid under spin_lock(sh->lock); - */ -struct stripe_head_state { - int syncing, expanding, expanded; - int locked, uptodate, to_read, to_write, failed, written; - int to_fill, compute, req_compute, non_overwrite; - int failed_num; - unsigned long ops_request; -}; - -/* r6_state - extra state data only relevant to r6 */ -struct r6_state { - int p_failed, q_failed, qd_idx, failed_num[2]; -}; - -/* Flags */ -#define R5_UPTODATE 0 /* page contains current data */ -#define R5_LOCKED 1 /* IO has been submitted on "req" */ -#define R5_OVERWRITE 2 /* towrite covers whole page */ -/* and some that are internal to handle_stripe */ -#define R5_Insync 3 /* rdev && rdev->in_sync at start */ -#define R5_Wantread 4 /* want to schedule a read */ -#define R5_Wantwrite 5 -#define R5_Overlap 7 /* There is a pending overlapping request on this block */ -#define R5_ReadError 8 /* seen a read error here recently */ -#define R5_ReWrite 9 /* have tried to over-write the readerror */ - -#define R5_Expanded 10 /* This block now has post-expand data */ -#define R5_Wantcompute 11 /* compute_block in progress treat as - * uptodate - */ -#define R5_Wantfill 12 /* dev->toread contains a bio that needs - * filling - */ -#define R5_Wantdrain 13 /* dev->towrite needs to be drained */ -/* - * Write method - */ -#define RECONSTRUCT_WRITE 1 -#define READ_MODIFY_WRITE 2 -/* not a write method, but a compute_parity mode */ -#define CHECK_PARITY 3 - -/* - * Stripe state - */ -#define STRIPE_HANDLE 2 -#define STRIPE_SYNCING 3 -#define STRIPE_INSYNC 4 -#define STRIPE_PREREAD_ACTIVE 5 -#define STRIPE_DELAYED 6 -#define STRIPE_DEGRADED 7 -#define STRIPE_BIT_DELAY 8 -#define STRIPE_EXPANDING 9 -#define STRIPE_EXPAND_SOURCE 10 -#define STRIPE_EXPAND_READY 11 -#define STRIPE_IO_STARTED 12 /* do not count towards 'bypass_count' */ -#define STRIPE_FULL_WRITE 13 /* all blocks are set to be overwritten */ -#define STRIPE_BIOFILL_RUN 14 -#define STRIPE_COMPUTE_RUN 15 -/* - * Operation request flags - */ -#define STRIPE_OP_BIOFILL 0 -#define STRIPE_OP_COMPUTE_BLK 1 -#define STRIPE_OP_PREXOR 2 -#define STRIPE_OP_BIODRAIN 3 -#define STRIPE_OP_POSTXOR 4 -#define STRIPE_OP_CHECK 5 - -/* - * 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 leave nothing locked. - */ - - -struct disk_info { - mdk_rdev_t *rdev; -}; - -struct raid5_private_data { - struct hlist_head *stripe_hashtbl; - mddev_t *mddev; - struct disk_info *spare; - int chunk_size, level, algorithm; - int max_degraded; - int raid_disks; - int max_nr_stripes; - - /* used during an expand */ - sector_t expand_progress; /* MaxSector when no expand happening */ - sector_t expand_lo; /* from here up to expand_progress it out-of-bounds - * as we haven't flushed the metadata yet - */ - int previous_raid_disks; - - 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 */ - 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][20]; - struct kmem_cache *slab_cache; /* for allocating stripes */ - - 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. - */ - - struct page *spare_page; /* Used when checking P/Q in raid6 */ - - /* - * Free stripes pool - */ - atomic_t active_stripes; - struct list_head inactive_list; - wait_queue_head_t wait_for_stripe; - wait_queue_head_t wait_for_overlap; - int inactive_blocked; /* release of inactive stripes blocked, - * waiting for 25% to be free - */ - int pool_size; /* number of disks in stripeheads in pool */ - spinlock_t device_lock; - struct disk_info *disks; -}; - -typedef struct raid5_private_data raid5_conf_t; - -#define mddev_to_conf(mddev) ((raid5_conf_t *) mddev->private) - -/* - * Our supported algorithms - */ -#define ALGORITHM_LEFT_ASYMMETRIC 0 -#define ALGORITHM_RIGHT_ASYMMETRIC 1 -#define ALGORITHM_LEFT_SYMMETRIC 2 -#define ALGORITHM_RIGHT_SYMMETRIC 3 - -#endif |