diff options
Diffstat (limited to 'include/linux/raid/raid5.h')
| -rw-r--r-- | include/linux/raid/raid5.h | 81 |
1 files changed, 78 insertions, 3 deletions
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h index b99d354f612..6fb9d94e6f2 100644 --- a/include/linux/raid/raid5.h +++ b/include/linux/raid/raid5.h @@ -116,13 +116,46 @@ * 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 needed unlockstripe schedule io + * 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. + * 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. */ struct stripe_head { @@ -136,11 +169,26 @@ struct stripe_head { spinlock_t lock; int bm_seq; /* sequence number for bitmap flushes */ int disks; /* disks in stripe */ + /* stripe_operations + * @pending - pending ops flags (set for request->issue->complete) + * @ack - submitted ops flags (set for issue->complete) + * @complete - completed ops flags (set for complete) + * @target - STRIPE_OP_COMPUTE_BLK target + * @count - raid5_runs_ops is set to run when this is non-zero + */ + struct stripe_operations { + unsigned long pending; + unsigned long ack; + unsigned long complete; + int target; + int count; + u32 zero_sum_result; + } ops; struct r5dev { struct bio req; struct bio_vec vec; struct page *page; - struct bio *toread, *towrite, *written; + 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 */ @@ -174,6 +222,15 @@ struct r6_state { #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_Wantprexor 13 /* distinguish blocks ready for rmw from + * other "towrites" + */ /* * Write method */ @@ -196,6 +253,24 @@ struct r6_state { #define STRIPE_EXPAND_SOURCE 10 #define STRIPE_EXPAND_READY 11 /* + * Operations flags (in issue order) + */ +#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 +#define STRIPE_OP_IO 6 + +/* modifiers to the base operations + * STRIPE_OP_MOD_REPAIR_PD - compute the parity block and write it back + * STRIPE_OP_MOD_DMA_CHECK - parity is not corrupted by the check + */ +#define STRIPE_OP_MOD_REPAIR_PD 7 +#define STRIPE_OP_MOD_DMA_CHECK 8 + +/* * Plugging: * * To improve write throughput, we need to delay the handling of some |