/* SPDX-License-Identifier: GPL-2.0 */#ifndef _RAID5_H#define _RAID5_H #include <linux/raid/xor.h>#include <linux/dmaengine.h>#include <linux/local_lock.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 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 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 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,}; #define DEFAULT_STRIPE_SIZE	4096struct 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; #if PAGE_SIZE != DEFAULT_STRIPE_SIZE	/* These pages will be used by bios in dev[i] */	struct page	**pages;	int	nr_pages;	/* page array size */	int	stripes_per_page;#endif	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;		unsigned int    offset;     /* offset of the 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[]; /* allocated depending of RAID geometry ("disks" member) */}; /* 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_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_ON_UNPLUG_LIST,	STRIPE_DISCARD,	STRIPE_ON_RELEASE_LIST,	STRIPE_BATCH_READY,	STRIPE_BATCH_ERR,	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;	struct md_rdev	*replacement;	struct page	*extra_page; /* extra page to use in prexor */}; /* * Stripe cache */ #define NR_STRIPES		256 #if PAGE_SIZE == DEFAULT_STRIPE_SIZE#define STRIPE_SIZE		PAGE_SIZE#define STRIPE_SHIFT		(PAGE_SHIFT - 9)#define STRIPE_SECTORS		(STRIPE_SIZE>>9)#endif #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 /* 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

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