* 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 {
atomic_t count; /* nr of active thread/requests */
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 */
};
+
+/* 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;
+};
+
+/* 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_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_Wantprexor 13 /* distinguish blocks ready for rmw from
+ * other "towrites"
+ */
/*
* Write method
*/
#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 */
+/*
+ * 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:
* 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 delayed 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.
+ * 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.
mddev_t *mddev;
struct disk_info *spare;
int chunk_size, level, algorithm;
- int raid_disks, working_disks, failed_disks;
+ 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 */
- char cache_name[20];
- kmem_cache_t *slab_cache; /* for allocating stripes */
+ 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;
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;
};
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff