linux/drivers/md/md-bitmap.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
 *
 * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
 */
#ifndef BITMAP_H
#define BITMAP_H 1

#define BITMAP_MAGIC 0x6d746962

/*
 * version 3 is host-endian order, this is deprecated and not used for new
 * array
 */
#define BITMAP_MAJOR_LO		3
#define BITMAP_MAJOR_HOSTENDIAN	3
/* version 4 is little-endian order, the default value */
#define BITMAP_MAJOR_HI		4
/* version 5 is only used for cluster */
#define BITMAP_MAJOR_CLUSTERED	5
/* version 6 is only used for lockless bitmap */
#define BITMAP_MAJOR_LOCKLESS	6

/* use these for bitmap->flags and bitmap->sb->state bit-fields */
enum bitmap_state {
	BITMAP_STALE	   = 1, /* the bitmap file is out of date or had -EIO */
	BITMAP_WRITE_ERROR = 2, /* A write error has occurred */
	BITMAP_FIRST_USE   = 3, /* llbitmap is just created */
	BITMAP_CLEAN       = 4, /* llbitmap is created with assume_clean */
	BITMAP_DAEMON_BUSY = 5, /* llbitmap daemon is not finished after daemon_sleep */
	BITMAP_HOSTENDIAN  =15,
};

/* the superblock at the front of the bitmap file -- little endian */
typedef struct bitmap_super_s {
	__le32 magic;        /*  0  BITMAP_MAGIC */
	__le32 version;      /*  4  the bitmap major for now, could change... */
	__u8  uuid[16];      /*  8  128 bit uuid - must match md device uuid */
	__le64 events;       /* 24  event counter for the bitmap (1)*/
	__le64 events_cleared;/*32  event counter when last bit cleared (2) */
	__le64 sync_size;    /* 40  the size of the md device's sync range(3) */
	__le32 state;        /* 48  bitmap state information */
	__le32 chunksize;    /* 52  the bitmap chunk size in bytes */
	__le32 daemon_sleep; /* 56  seconds between disk flushes */
	__le32 write_behind; /* 60  number of outstanding write-behind writes */
	__le32 sectors_reserved; /* 64 number of 512-byte sectors that are
				  * reserved for the bitmap. */
	__le32 nodes;        /* 68 the maximum number of nodes in cluster. */
	__u8 cluster_name[64]; /* 72 cluster name to which this md belongs */
	__u8  pad[256 - 136]; /* set to zero */
} bitmap_super_t;

/* notes:
 * (1) This event counter is updated before the eventcounter in the md superblock
 *    When a bitmap is loaded, it is only accepted if this event counter is equal
 *    to, or one greater than, the event counter in the superblock.
 * (2) This event counter is updated when the other one is *if*and*only*if* the
 *    array is not degraded.  As bits are not cleared when the array is degraded,
 *    this represents the last time that any bits were cleared.
 *    If a device is being added that has an event count with this value or
 *    higher, it is accepted as conforming to the bitmap.
 * (3)This is the number of sectors represented by the bitmap, and is the range that
 *    resync happens across.  For raid1 and raid5/6 it is the size of individual
 *    devices.  For raid10 it is the size of the array.
 */

struct md_bitmap_stats {
	u64		events_cleared;
	int		behind_writes;
	bool		behind_wait;

	unsigned long	missing_pages;
	unsigned long	file_pages;
	unsigned long	sync_size;
	unsigned long	pages;
	struct file	*file;
};

typedef void (md_bitmap_fn)(struct mddev *mddev, sector_t offset,
			    unsigned long sectors);

struct bitmap_operations {
	struct md_submodule_head head;

	bool (*enabled)(void *data, bool flush);
	int (*create)(struct mddev *mddev);
	int (*resize)(struct mddev *mddev, sector_t blocks, int chunksize);

	int (*load)(struct mddev *mddev);
	void (*destroy)(struct mddev *mddev);
	void (*flush)(struct mddev *mddev);
	void (*write_all)(struct mddev *mddev);
	void (*dirty_bits)(struct mddev *mddev, unsigned long s,
			   unsigned long e);
	void (*unplug)(struct mddev *mddev, bool sync);
	void (*daemon_work)(struct mddev *mddev);

	void (*start_behind_write)(struct mddev *mddev);
	void (*end_behind_write)(struct mddev *mddev);
	void (*wait_behind_writes)(struct mddev *mddev);

	md_bitmap_fn *start_write;
	md_bitmap_fn *end_write;
	md_bitmap_fn *start_discard;
	md_bitmap_fn *end_discard;

	sector_t (*skip_sync_blocks)(struct mddev *mddev, sector_t offset);
	bool (*blocks_synced)(struct mddev *mddev, sector_t offset);
	bool (*start_sync)(struct mddev *mddev, sector_t offset,
			   sector_t *blocks, bool degraded);
	void (*end_sync)(struct mddev *mddev, sector_t offset, sector_t *blocks);
	void (*cond_end_sync)(struct mddev *mddev, sector_t sector, bool force);
	void (*close_sync)(struct mddev *mddev);

	void (*update_sb)(void *data);
	int (*get_stats)(void *data, struct md_bitmap_stats *stats);

	void (*sync_with_cluster)(struct mddev *mddev,
				  sector_t old_lo, sector_t old_hi,
				  sector_t new_lo, sector_t new_hi);
	void *(*get_from_slot)(struct mddev *mddev, int slot);
	int (*copy_from_slot)(struct mddev *mddev, int slot, sector_t *lo,
			      sector_t *hi, bool clear_bits);
	void (*set_pages)(void *data, unsigned long pages);
	void (*free)(void *data);

	struct attribute_group *group;
};

/* the bitmap API */
static inline bool md_bitmap_registered(struct mddev *mddev)
{
	return mddev->bitmap_ops != NULL;
}

static inline bool md_bitmap_enabled(struct mddev *mddev, bool flush)
{
	/* bitmap_ops must be registered before creating bitmap. */
	if (!md_bitmap_registered(mddev))
		return false;

	if (!mddev->bitmap)
		return false;

	return mddev->bitmap_ops->enabled(mddev->bitmap, flush);
}

static inline bool md_bitmap_start_sync(struct mddev *mddev, sector_t offset,
					sector_t *blocks, bool degraded)
{
	/* always resync if no bitmap */
	if (!md_bitmap_enabled(mddev, false)) {
		*blocks = 1024;
		return true;
	}

	return mddev->bitmap_ops->start_sync(mddev, offset, blocks, degraded);
}

static inline void md_bitmap_end_sync(struct mddev *mddev, sector_t offset,
				      sector_t *blocks)
{
	if (!md_bitmap_enabled(mddev, false)) {
		*blocks = 1024;
		return;
	}

	mddev->bitmap_ops->end_sync(mddev, offset, blocks);
}

#ifdef CONFIG_MD_BITMAP
int md_bitmap_init(void);
void md_bitmap_exit(void);
#else
static inline int md_bitmap_init(void)
{
	return 0;
}
static inline void md_bitmap_exit(void)
{
}
#endif

#ifdef CONFIG_MD_LLBITMAP
int md_llbitmap_init(void);
void md_llbitmap_exit(void);
#else
static inline int md_llbitmap_init(void)
{
	return 0;
}
static inline void md_llbitmap_exit(void)
{
}
#endif

#endif