v4.19.13 snapshot.
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
new file mode 100644
index 0000000..8474c22
--- /dev/null
+++ b/drivers/md/raid5.h
@@ -0,0 +1,769 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#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*/
+
+ union {
+ struct r5l_io_unit *log_io;
+ struct ppl_io_unit *ppl_io;
+ };
+
+ struct list_head log_list;
+ sector_t log_start; /* first meta block on the journal */
+ struct list_head r5c; /* for r5c_cache->stripe_in_journal */
+
+ struct page *ppl_page; /* partial parity of this stripe */
+ /**
+ * 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;
+ u32 log_checksum;
+ unsigned short write_hint;
+ } 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 injournal, just_cached;
+ int failed_num[2];
+ int p_failed, q_failed;
+ int dec_preread_active;
+ unsigned long ops_request;
+
+ struct md_rdev *blocked_rdev;
+ int handle_bad_blocks;
+ int log_failed;
+ int waiting_extra_page;
+};
+
+/* 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 */
+ R5_InJournal, /* data being written is in the journal device.
+ * if R5_InJournal is set for parity pd_idx, all the
+ * data and parity being written are in the journal
+ * device
+ */
+ R5_OrigPageUPTDODATE, /* with write back cache, we read old data into
+ * dev->orig_page for prexor. When this flag is
+ * set, orig_page contains latest data in the
+ * raid disk.
+ */
+};
+
+/*
+ * 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.
+ */
+ STRIPE_LOG_TRAPPED, /* trapped into log (see raid5-cache.c)
+ * this bit is used in two scenarios:
+ *
+ * 1. write-out phase
+ * set in first entry of r5l_write_stripe
+ * clear in second entry of r5l_write_stripe
+ * used to bypass logic in handle_stripe
+ *
+ * 2. caching phase
+ * set in r5c_try_caching_write()
+ * clear when journal write is done
+ * used to initiate r5c_cache_data()
+ * also used to bypass logic in handle_stripe
+ */
+ STRIPE_R5C_CACHING, /* the stripe is in caching phase
+ * see more detail in the raid5-cache.c
+ */
+ STRIPE_R5C_PARTIAL_STRIPE, /* in r5c cache (to-be/being handled or
+ * in conf->r5c_partial_stripe_list)
+ */
+ STRIPE_R5C_FULL_STRIPE, /* in r5c cache (to-be/being handled or
+ * in conf->r5c_full_stripe_list)
+ */
+ STRIPE_R5C_PREFLUSH, /* need to flush journal device */
+};
+
+#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,
+ STRIPE_OP_PARTIAL_PARITY,
+};
+
+/*
+ * 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.
+ */
+
+/* Note: disk_info.rdev can be set to NULL asynchronously by raid5_remove_disk.
+ * There are three safe ways to access disk_info.rdev.
+ * 1/ when holding mddev->reconfig_mutex
+ * 2/ when resync/recovery/reshape is known to be happening - i.e. in code that
+ * is called as part of performing resync/recovery/reshape.
+ * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
+ * and if it is non-NULL, increment rdev->nr_pending before dropping the RCU
+ * lock.
+ * When .rdev is set to NULL, the nr_pending count checked again and if
+ * it has been incremented, the pointer is put back in .rdev.
+ */
+
+struct disk_info {
+ struct md_rdev *rdev, *replacement;
+ struct page *extra_page; /* extra page to use in prexor */
+};
+
+/*
+ * Stripe cache
+ */
+
+#define NR_STRIPES 256
+#define STRIPE_SIZE PAGE_SIZE
+#define STRIPE_SHIFT (PAGE_SHIFT - 9)
+#define STRIPE_SECTORS (STRIPE_SIZE>>9)
+#define IO_THRESHOLD 1
+#define BYPASS_THRESHOLD 1
+#define NR_HASH (PAGE_SIZE / sizeof(struct hlist_head))
+#define HASH_MASK (NR_HASH - 1)
+#define MAX_STRIPE_BATCH 8
+
+/* bio's attached to a stripe+device for I/O are linked together in bi_sector
+ * order without overlap. There may be several bio's per stripe+device, and
+ * a bio could span several devices.
+ * When walking this list for a particular stripe+device, we must never proceed
+ * beyond a bio that extends past this device, as the next bio might no longer
+ * be valid.
+ * This function is used to determine the 'next' bio in the list, given the
+ * sector of the current stripe+device
+ */
+static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
+{
+ int sectors = bio_sectors(bio);
+
+ if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
+ return bio->bi_next;
+ else
+ return NULL;
+}
+
+/* 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 list_head loprio_list;
+ struct r5conf *conf;
+ struct r5worker *workers;
+ int stripes_cnt;
+};
+
+/*
+ * r5c journal modes of the array: write-back or write-through.
+ * write-through mode has identical behavior as existing log only
+ * implementation.
+ */
+enum r5c_journal_mode {
+ R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
+ R5C_JOURNAL_MODE_WRITE_BACK = 1,
+};
+
+enum r5_cache_state {
+ R5_INACTIVE_BLOCKED, /* release of inactive stripes blocked,
+ * waiting for 25% to be free
+ */
+ R5_ALLOC_MORE, /* It might help to allocate another
+ * stripe.
+ */
+ R5_DID_ALLOC, /* A stripe was allocated, don't allocate
+ * more until at least one has been
+ * released. This avoids flooding
+ * the cache.
+ */
+ R5C_LOG_TIGHT, /* log device space tight, need to
+ * prioritize stripes at last_checkpoint
+ */
+ R5C_LOG_CRITICAL, /* log device is running out of space,
+ * only process stripes that are already
+ * occupying the log
+ */
+ R5C_EXTRA_PAGE_IN_USE, /* a stripe is using disk_info.extra_page
+ * for prexor
+ */
+};
+
+#define PENDING_IO_MAX 512
+#define PENDING_IO_ONE_FLUSH 128
+struct r5pending_data {
+ struct list_head sibling;
+ sector_t sector; /* stripe sector */
+ struct bio_list bios;
+};
+
+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 loprio_list; /* low priority stripes */
+ 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 */
+ unsigned int retry_read_offset; /* sector offset into retry_read_aligned */
+ 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;
+ int scribble_disks;
+ int scribble_sectors;
+ struct hlist_node node;
+
+ /*
+ * Free stripes pool
+ */
+ atomic_t active_stripes;
+ struct list_head inactive_list[NR_STRIPE_HASH_LOCKS];
+
+ atomic_t r5c_cached_full_stripes;
+ struct list_head r5c_full_stripe_list;
+ atomic_t r5c_cached_partial_stripes;
+ struct list_head r5c_partial_stripe_list;
+ atomic_t r5c_flushing_full_stripes;
+ atomic_t r5c_flushing_partial_stripes;
+
+ atomic_t empty_inactive_list_nr;
+ struct llist_head released_stripes;
+ wait_queue_head_t wait_for_quiescent;
+ wait_queue_head_t wait_for_stripe;
+ wait_queue_head_t wait_for_overlap;
+ unsigned long cache_state;
+ struct shrinker shrinker;
+ int pool_size; /* number of disks in stripeheads in pool */
+ spinlock_t device_lock;
+ struct disk_info *disks;
+ struct bio_set bio_split;
+
+ /* 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;
+ struct r5l_log *log;
+ void *log_private;
+
+ spinlock_t pending_bios_lock;
+ bool batch_bio_dispatch;
+ struct r5pending_data *pending_data;
+ struct list_head free_list;
+ struct list_head pending_list;
+ int pending_data_cnt;
+ struct r5pending_data *next_pending_data;
+};
+
+
+/*
+ * 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);
+extern sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous);
+extern void raid5_release_stripe(struct stripe_head *sh);
+extern sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
+ int previous, int *dd_idx,
+ struct stripe_head *sh);
+extern struct stripe_head *
+raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
+ int previous, int noblock, int noquiesce);
+extern int raid5_calc_degraded(struct r5conf *conf);
+extern int r5c_journal_mode_set(struct mddev *mddev, int journal_mode);
+#endif