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#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
|