include/linux/raid/bitmap.h - kernel/msm - Gitiles

 /*
  * 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_MAJOR_LO 3
 /* version 4 insists the bitmap is in little-endian order
  * with version 3, it is host-endian which is non-portable
  */
 #define BITMAP_MAJOR_HI 4
 #define	BITMAP_MAJOR_HOSTENDIAN 3

 #define BITMAP_MINOR 39

 /*
  * in-memory bitmap:
  *
  * Use 16 bit block counters to track pending writes to each "chunk".
  * The 2 high order bits are special-purpose, the first is a flag indicating
  * whether a resync is needed.  The second is a flag indicating whether a
  * resync is active.
  * This means that the counter is actually 14 bits:
  *
  * +--------+--------+------------------------------------------------+
  * | resync | resync |               counter                          |
  * | needed | active |                                                |
  * |  (0-1) |  (0-1) |              (0-16383)                         |
  * +--------+--------+------------------------------------------------+
  *
  * The "resync needed" bit is set when:
  *    a '1' bit is read from storage at startup.
  *    a write request fails on some drives
  *    a resync is aborted on a chunk with 'resync active' set
  * It is cleared (and resync-active set) when a resync starts across all drives
  * of the chunk.
  *
  *
  * The "resync active" bit is set when:
  *    a resync is started on all drives, and resync_needed is set.
  *       resync_needed will be cleared (as long as resync_active wasn't already set).
  * It is cleared when a resync completes.
  *
  * The counter counts pending write requests, plus the on-disk bit.
  * When the counter is '1' and the resync bits are clear, the on-disk
  * bit can be cleared aswell, thus setting the counter to 0.
  * When we set a bit, or in the counter (to start a write), if the fields is
  * 0, we first set the disk bit and set the counter to 1.
  *
  * If the counter is 0, the on-disk bit is clear and the stipe is clean
  * Anything that dirties the stipe pushes the counter to 2 (at least)
  * and sets the on-disk bit (lazily).
  * If a periodic sweep find the counter at 2, it is decremented to 1.
  * If the sweep find the counter at 1, the on-disk bit is cleared and the
  * counter goes to zero.
  *
  * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
  * counters as a fallback when "page" memory cannot be allocated:
  *
  * Normal case (page memory allocated):
  *
  *     page pointer (32-bit)
  *
  *     [ ] ------+
  *               |
  *               +-------> [   ][   ]..[   ] (4096 byte page == 2048 counters)
  *                          c1   c2    c2048
  *
  * Hijacked case (page memory allocation failed):
  *
  *     hijacked page pointer (32-bit)
  *
  *     [		  ][		  ] (no page memory allocated)
  *      counter #1 (16-bit) counter #2 (16-bit)
  *
  */

 #ifdef __KERNEL__

 #define PAGE_BITS (PAGE_SIZE << 3)
 #define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)

 typedef __u16 bitmap_counter_t;
 #define COUNTER_BITS 16
 #define COUNTER_BIT_SHIFT 4
 #define COUNTER_BYTE_RATIO (COUNTER_BITS / 8)
 #define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3)

 #define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1)))
 #define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2)))
 #define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1)
 #define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK)
 #define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK)
 #define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX)

 /* how many counters per page? */
 #define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS)
 /* same, except a shift value for more efficient bitops */
 #define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT)
 /* same, except a mask value for more efficient bitops */
 #define PAGE_COUNTER_MASK  (PAGE_COUNTER_RATIO - 1)

 #define BITMAP_BLOCK_SIZE 512
 #define BITMAP_BLOCK_SHIFT 9

 /* how many blocks per chunk? (this is variable) */
 #define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->chunksize >> BITMAP_BLOCK_SHIFT)
 #define CHUNK_BLOCK_SHIFT(bitmap) ((bitmap)->chunkshift - BITMAP_BLOCK_SHIFT)
 #define CHUNK_BLOCK_MASK(bitmap) (CHUNK_BLOCK_RATIO(bitmap) - 1)

 /* when hijacked, the counters and bits represent even larger "chunks" */
 /* there will be 1024 chunks represented by each counter in the page pointers */
 #define PAGEPTR_BLOCK_RATIO(bitmap) \
 			(CHUNK_BLOCK_RATIO(bitmap) << PAGE_COUNTER_SHIFT >> 1)
 #define PAGEPTR_BLOCK_SHIFT(bitmap) \
 			(CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1)
 #define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1)

 /*
  * on-disk bitmap:
  *
  * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
  * file a page at a time. There's a superblock at the start of the file.
  */

 /* map chunks (bits) to file pages - offset by the size of the superblock */
 #define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3))

 #endif

 /*
  * bitmap structures:
  */

 #define BITMAP_MAGIC 0x6d746962

 /* use these for bitmap->flags and bitmap->sb->state bit-fields */
 enum bitmap_state {
 	BITMAP_ACTIVE = 0x001, /* the bitmap is in use */
 	BITMAP_STALE  = 0x002,  /* the bitmap file is out of date or had -EIO */
 	BITMAP_HOSTENDIAN = 0x8000,
 };

 /* the superblock at the front of the bitmap file -- little endian */
 typedef struct bitmap_super_s {
 	__u32 magic;        /*  0  BITMAP_MAGIC */
 	__u32 version;      /*  4  the bitmap major for now, could change... */
 	__u8  uuid[16];     /*  8  128 bit uuid - must match md device uuid */
 	__u64 events;       /* 24  event counter for the bitmap (1)*/
 	__u64 events_cleared;/*32  event counter when last bit cleared (2) */
 	__u64 sync_size;    /* 40  the size of the md device's sync range(3) */
 	__u32 state;        /* 48  bitmap state information */
 	__u32 chunksize;    /* 52  the bitmap chunk size in bytes */
 	__u32 daemon_sleep; /* 56  seconds between disk flushes */
 	__u32 write_behind; /* 60  number of outstanding write-behind writes */

 	__u8  pad[256 - 64]; /* 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.
  */

 #ifdef __KERNEL__

 /* the in-memory bitmap is represented by bitmap_pages */
 struct bitmap_page {
 	/*
 	 * map points to the actual memory page
 	 */
 	char *map;
 	/*
 	 * in emergencies (when map cannot be alloced), hijack the map
 	 * pointer and use it as two counters itself
 	 */
 	unsigned int hijacked:1;
 	/*
 	 * count of dirty bits on the page
 	 */
 	unsigned int  count:31;
 };

 /* keep track of bitmap file pages that have pending writes on them */
 struct page_list {
 	struct list_head list;
 	struct page *page;
 };

 /* the main bitmap structure - one per mddev */
 struct bitmap {
 	struct bitmap_page *bp;
 	unsigned long pages; /* total number of pages in the bitmap */
 	unsigned long missing_pages; /* number of pages not yet allocated */

 	mddev_t *mddev; /* the md device that the bitmap is for */

 	int counter_bits; /* how many bits per block counter */

 	/* bitmap chunksize -- how much data does each bit represent? */
 	unsigned long chunksize;
 	unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */
 	unsigned long chunks; /* total number of data chunks for the array */

 	/* We hold a count on the chunk currently being synced, and drop
 	 * it when the last block is started.  If the resync is aborted
 	 * midway, we need to be able to drop that count, so we remember
 	 * the counted chunk..
 	 */
 	unsigned long syncchunk;

 	__u64	events_cleared;

 	/* bitmap spinlock */
 	spinlock_t lock;

 	long offset; /* offset from superblock if file is NULL */
 	struct file *file; /* backing disk file */
 	struct page *sb_page; /* cached copy of the bitmap file superblock */
 	struct page **filemap; /* list of cache pages for the file */
 	unsigned long *filemap_attr; /* attributes associated w/ filemap pages */
 	unsigned long file_pages; /* number of pages in the file */

 	unsigned long flags;

 	unsigned long max_write_behind; /* write-behind mode */
 	atomic_t behind_writes;

 	/*
 	 * the bitmap daemon - periodically wakes up and sweeps the bitmap
 	 * file, cleaning up bits and flushing out pages to disk as necessary
 	 */
 	unsigned long daemon_lastrun; /* jiffies of last run */
 	unsigned long daemon_sleep; /* how many seconds between updates? */

 	/*
 	 * bitmap_writeback_daemon waits for file-pages that have been written,
 	 * as there is no way to get a call-back when a page write completes.
 	 */
 	mdk_thread_t *writeback_daemon;
 	spinlock_t write_lock;
 	wait_queue_head_t write_wait;
 	struct list_head complete_pages;
 	mempool_t *write_pool;
 };

 /* the bitmap API */

 /* these are used only by md/bitmap */
 int  bitmap_create(mddev_t *mddev);
 void bitmap_flush(mddev_t *mddev);
 void bitmap_destroy(mddev_t *mddev);
 int  bitmap_active(struct bitmap *bitmap);

 char *file_path(struct file *file, char *buf, int count);
 void bitmap_print_sb(struct bitmap *bitmap);
 int bitmap_update_sb(struct bitmap *bitmap);

 int  bitmap_setallbits(struct bitmap *bitmap);
 void bitmap_write_all(struct bitmap *bitmap);

 /* these are exported */
 int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
 			unsigned long sectors, int behind);
 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
 			unsigned long sectors, int success, int behind);
 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int degraded);
 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted);
 void bitmap_close_sync(struct bitmap *bitmap);

 int bitmap_unplug(struct bitmap *bitmap);
 int bitmap_daemon_work(struct bitmap *bitmap);
 #endif

 #endif
	/*
	* 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_MAJOR_LO 3
	/* version 4 insists the bitmap is in little-endian order
	* with version 3, it is host-endian which is non-portable
	*/
	#define BITMAP_MAJOR_HI 4
	#define BITMAP_MAJOR_HOSTENDIAN 3

	#define BITMAP_MINOR 39

	/*
	* in-memory bitmap:
	*
	* Use 16 bit block counters to track pending writes to each "chunk".
	* The 2 high order bits are special-purpose, the first is a flag indicating
	* whether a resync is needed. The second is a flag indicating whether a
	* resync is active.
	* This means that the counter is actually 14 bits:
	*
	* +--------+--------+------------------------------------------------+
	* \| resync \| resync \| counter \|
	* \| needed \| active \| \|
	* \| (0-1) \| (0-1) \| (0-16383) \|
	* +--------+--------+------------------------------------------------+
	*
	* The "resync needed" bit is set when:
	* a '1' bit is read from storage at startup.
	* a write request fails on some drives
	* a resync is aborted on a chunk with 'resync active' set
	* It is cleared (and resync-active set) when a resync starts across all drives
	* of the chunk.
	*
	*
	* The "resync active" bit is set when:
	* a resync is started on all drives, and resync_needed is set.
	* resync_needed will be cleared (as long as resync_active wasn't already set).
	* It is cleared when a resync completes.
	*
	* The counter counts pending write requests, plus the on-disk bit.
	* When the counter is '1' and the resync bits are clear, the on-disk
	* bit can be cleared aswell, thus setting the counter to 0.
	* When we set a bit, or in the counter (to start a write), if the fields is
	* 0, we first set the disk bit and set the counter to 1.
	*
	* If the counter is 0, the on-disk bit is clear and the stipe is clean
	* Anything that dirties the stipe pushes the counter to 2 (at least)
	* and sets the on-disk bit (lazily).
	* If a periodic sweep find the counter at 2, it is decremented to 1.
	* If the sweep find the counter at 1, the on-disk bit is cleared and the
	* counter goes to zero.
	*
	* Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
	* counters as a fallback when "page" memory cannot be allocated:
	*
	* Normal case (page memory allocated):
	*
	* page pointer (32-bit)
	*
	* [ ] ------+
	* \|
	* +-------> [ ][ ]..[ ] (4096 byte page == 2048 counters)
	* c1 c2 c2048
	*
	* Hijacked case (page memory allocation failed):
	*
	* hijacked page pointer (32-bit)
	*
	* [ ][ ] (no page memory allocated)
	* counter #1 (16-bit) counter #2 (16-bit)
	*
	*/

	#ifdef __KERNEL__

	#define PAGE_BITS (PAGE_SIZE << 3)
	#define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)

	typedef __u16 bitmap_counter_t;
	#define COUNTER_BITS 16
	#define COUNTER_BIT_SHIFT 4
	#define COUNTER_BYTE_RATIO (COUNTER_BITS / 8)
	#define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3)

	#define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1)))
	#define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2)))
	#define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1)
	#define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK)
	#define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK)
	#define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX)

	/* how many counters per page? */
	#define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS)
	/* same, except a shift value for more efficient bitops */
	#define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT)
	/* same, except a mask value for more efficient bitops */
	#define PAGE_COUNTER_MASK (PAGE_COUNTER_RATIO - 1)

	#define BITMAP_BLOCK_SIZE 512
	#define BITMAP_BLOCK_SHIFT 9

	/* how many blocks per chunk? (this is variable) */
	#define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->chunksize >> BITMAP_BLOCK_SHIFT)
	#define CHUNK_BLOCK_SHIFT(bitmap) ((bitmap)->chunkshift - BITMAP_BLOCK_SHIFT)
	#define CHUNK_BLOCK_MASK(bitmap) (CHUNK_BLOCK_RATIO(bitmap) - 1)

	/* when hijacked, the counters and bits represent even larger "chunks" */
	/* there will be 1024 chunks represented by each counter in the page pointers */
	#define PAGEPTR_BLOCK_RATIO(bitmap) \
	(CHUNK_BLOCK_RATIO(bitmap) << PAGE_COUNTER_SHIFT >> 1)
	#define PAGEPTR_BLOCK_SHIFT(bitmap) \
	(CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1)
	#define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1)

	/*
	* on-disk bitmap:
	*
	* Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
	* file a page at a time. There's a superblock at the start of the file.
	*/

	/* map chunks (bits) to file pages - offset by the size of the superblock */
	#define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3))

	#endif

	/*
	* bitmap structures:
	*/

	#define BITMAP_MAGIC 0x6d746962

	/* use these for bitmap->flags and bitmap->sb->state bit-fields */
	enum bitmap_state {
	BITMAP_ACTIVE = 0x001, /* the bitmap is in use */
	BITMAP_STALE = 0x002, /* the bitmap file is out of date or had -EIO */
	BITMAP_HOSTENDIAN = 0x8000,
	};

	/* the superblock at the front of the bitmap file -- little endian */
	typedef struct bitmap_super_s {
	__u32 magic; /* 0 BITMAP_MAGIC */
	__u32 version; /* 4 the bitmap major for now, could change... */
	__u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */
	__u64 events; /* 24 event counter for the bitmap (1)*/
	__u64 events_cleared;/32 event counter when last bit cleared (2) /
	__u64 sync_size; /* 40 the size of the md device's sync range(3) */
	__u32 state; /* 48 bitmap state information */
	__u32 chunksize; /* 52 the bitmap chunk size in bytes */
	__u32 daemon_sleep; /* 56 seconds between disk flushes */
	__u32 write_behind; /* 60 number of outstanding write-behind writes */

	__u8 pad[256 - 64]; /* 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 ifandonlyif* 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.
	*/

	#ifdef __KERNEL__

	/* the in-memory bitmap is represented by bitmap_pages */
	struct bitmap_page {
	/*
	* map points to the actual memory page
	*/
	char *map;
	/*
	* in emergencies (when map cannot be alloced), hijack the map
	* pointer and use it as two counters itself
	*/
	unsigned int hijacked:1;
	/*
	* count of dirty bits on the page
	*/
	unsigned int count:31;
	};

	/* keep track of bitmap file pages that have pending writes on them */
	struct page_list {
	struct list_head list;
	struct page *page;
	};

	/* the main bitmap structure - one per mddev */
	struct bitmap {
	struct bitmap_page *bp;
	unsigned long pages; /* total number of pages in the bitmap */
	unsigned long missing_pages; /* number of pages not yet allocated */

	mddev_t mddev; / the md device that the bitmap is for */

	int counter_bits; /* how many bits per block counter */

	/* bitmap chunksize -- how much data does each bit represent? */
	unsigned long chunksize;
	unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */
	unsigned long chunks; /* total number of data chunks for the array */

	/* We hold a count on the chunk currently being synced, and drop
	* it when the last block is started. If the resync is aborted
	* midway, we need to be able to drop that count, so we remember
	* the counted chunk..
	*/
	unsigned long syncchunk;

	__u64 events_cleared;

	/* bitmap spinlock */
	spinlock_t lock;

	long offset; /* offset from superblock if file is NULL */
	struct file file; / backing disk file */
	struct page sb_page; / cached copy of the bitmap file superblock */
	struct page *filemap; / list of cache pages for the file */
	unsigned long filemap_attr; / attributes associated w/ filemap pages */
	unsigned long file_pages; /* number of pages in the file */

	unsigned long flags;

	unsigned long max_write_behind; /* write-behind mode */
	atomic_t behind_writes;

	/*
	* the bitmap daemon - periodically wakes up and sweeps the bitmap
	* file, cleaning up bits and flushing out pages to disk as necessary
	*/
	unsigned long daemon_lastrun; /* jiffies of last run */
	unsigned long daemon_sleep; /* how many seconds between updates? */

	/*
	* bitmap_writeback_daemon waits for file-pages that have been written,
	* as there is no way to get a call-back when a page write completes.
	*/
	mdk_thread_t *writeback_daemon;
	spinlock_t write_lock;
	wait_queue_head_t write_wait;
	struct list_head complete_pages;
	mempool_t *write_pool;
	};

	/* the bitmap API */

	/* these are used only by md/bitmap */
	int bitmap_create(mddev_t *mddev);
	void bitmap_flush(mddev_t *mddev);
	void bitmap_destroy(mddev_t *mddev);
	int bitmap_active(struct bitmap *bitmap);

	char file_path(struct file file, char *buf, int count);
	void bitmap_print_sb(struct bitmap *bitmap);
	int bitmap_update_sb(struct bitmap *bitmap);

	int bitmap_setallbits(struct bitmap *bitmap);
	void bitmap_write_all(struct bitmap *bitmap);

	/* these are exported */
	int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
	unsigned long sectors, int behind);
	void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
	unsigned long sectors, int success, int behind);
	int bitmap_start_sync(struct bitmap bitmap, sector_t offset, int blocks, int degraded);
	void bitmap_end_sync(struct bitmap bitmap, sector_t offset, int blocks, int aborted);
	void bitmap_close_sync(struct bitmap *bitmap);

	int bitmap_unplug(struct bitmap *bitmap);
	int bitmap_daemon_work(struct bitmap *bitmap);
	#endif

	#endif