raid1.h 5.1 KB
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#ifndef _RAID1_H
#define _RAID1_H

struct mirror_info {
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	struct md_rdev	*rdev;
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	sector_t	head_position;
};

/*
 * memory pools need a pointer to the mddev, so they can force an unplug
 * when memory is tight, and a count of the number of drives that the
 * pool was allocated for, so they know how much to allocate and free.
 * mddev->raid_disks cannot be used, as it can change while a pool is active
 * These two datums are stored in a kmalloced struct.
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 * The 'raid_disks' here is twice the raid_disks in r1conf.
 * This allows space for each 'real' device can have a replacement in the
 * second half of the array.
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 */

struct pool_info {
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	struct mddev *mddev;
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	int	raid_disks;
};

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struct r1conf {
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	struct mddev		*mddev;
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	struct mirror_info	*mirrors;	/* twice 'raid_disks' to
						 * allow for replacements.
						 */
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	int			raid_disks;
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	/* When choose the best device for a read (read_balance())
	 * we try to keep sequential reads one the same device
	 * using 'last_used' and 'next_seq_sect'
	 */
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	int			last_used;
	sector_t		next_seq_sect;
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	/* During resync, read_balancing is only allowed on the part
	 * of the array that has been resynced.  'next_resync' tells us
	 * where that is.
	 */
	sector_t		next_resync;

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	spinlock_t		device_lock;

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	/* list of 'struct r1bio' that need to be processed by raid1d,
	 * whether to retry a read, writeout a resync or recovery
	 * block, or anything else.
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	 */
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	struct list_head	retry_list;
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	/* queue pending writes to be submitted on unplug */
	struct bio_list		pending_bio_list;
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	int			pending_count;
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	/* for use when syncing mirrors:
	 * We don't allow both normal IO and resync/recovery IO at
	 * the same time - resync/recovery can only happen when there
	 * is no other IO.  So when either is active, the other has to wait.
	 * See more details description in raid1.c near raise_barrier().
	 */
	wait_queue_head_t	wait_barrier;
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	spinlock_t		resync_lock;
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	int			nr_pending;
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	int			nr_waiting;
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	int			nr_queued;
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	int			barrier;
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	/* Set to 1 if a full sync is needed, (fresh device added).
	 * Cleared when a sync completes.
	 */
	int			fullsync;
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	/* When the same as mddev->recovery_disabled we don't allow
	 * recovery to be attempted as we expect a read error.
	 */
	int			recovery_disabled;
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	/* poolinfo contains information about the content of the
	 * mempools - it changes when the array grows or shrinks
	 */
	struct pool_info	*poolinfo;
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	mempool_t		*r1bio_pool;
	mempool_t		*r1buf_pool;
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	/* temporary buffer to synchronous IO when attempting to repair
	 * a read error.
	 */
	struct page		*tmppage;


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	/* When taking over an array from a different personality, we store
	 * the new thread here until we fully activate the array.
	 */
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	struct md_thread	*thread;
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};

/*
 * this is our 'private' RAID1 bio.
 *
 * it contains information about what kind of IO operations were started
 * for this RAID1 operation, and about their status:
 */

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struct r1bio {
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	atomic_t		remaining; /* 'have we finished' count,
					    * used from IRQ handlers
					    */
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	atomic_t		behind_remaining; /* number of write-behind ios remaining
						 * in this BehindIO request
						 */
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	sector_t		sector;
	int			sectors;
	unsigned long		state;
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	struct mddev		*mddev;
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	/*
	 * original bio going to /dev/mdx
	 */
	struct bio		*master_bio;
	/*
	 * if the IO is in READ direction, then this is where we read
	 */
	int			read_disk;

	struct list_head	retry_list;
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	/* Next two are only valid when R1BIO_BehindIO is set */
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	struct bio_vec		*behind_bvecs;
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	int			behind_page_count;
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	/*
	 * if the IO is in WRITE direction, then multiple bios are used.
	 * We choose the number when they are allocated.
	 */
	struct bio		*bios[0];
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	/* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
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};

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/* when we get a read error on a read-only array, we redirect to another
 * device without failing the first device, or trying to over-write to
 * correct the read error.  To keep track of bad blocks on a per-bio
 * level, we store IO_BLOCKED in the appropriate 'bios' pointer
 */
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#define IO_BLOCKED ((struct bio *)1)
/* When we successfully write to a known bad-block, we need to remove the
 * bad-block marking which must be done from process context.  So we record
 * the success by setting bios[n] to IO_MADE_GOOD
 */
#define IO_MADE_GOOD ((struct bio *)2)

#define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
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/* bits for r1bio.state */
#define	R1BIO_Uptodate	0
#define	R1BIO_IsSync	1
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#define	R1BIO_Degraded	2
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#define	R1BIO_BehindIO	3
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/* Set ReadError on bios that experience a readerror so that
 * raid1d knows what to do with them.
 */
#define R1BIO_ReadError 4
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/* For write-behind requests, we call bi_end_io when
 * the last non-write-behind device completes, providing
 * any write was successful.  Otherwise we call when
 * any write-behind write succeeds, otherwise we call
 * with failure when last write completes (and all failed).
 * Record that bi_end_io was called with this flag...
 */
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#define	R1BIO_Returned 6
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/* If a write for this request means we can clear some
 * known-bad-block records, we set this flag
 */
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#define	R1BIO_MadeGood 7
#define	R1BIO_WriteError 8
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extern int md_raid1_congested(struct mddev *mddev, int bits);
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#endif
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