/* * 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 /* * 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 as well, 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_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_SHIFT 9 #endif /* * bitmap structures: */ #define BITMAP_MAGIC 0x6d746962 /* 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_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. */ 	__u8  pad[256 - 68]; /* 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;	/*	 * If any counter in this page is '1' or '2' - and so could be	 * cleared then that page is marked as 'pending'	 */	unsigned int pending:1;	/*	 * count of dirty bits on the page	 */	unsigned int  count:30;}; /* the main bitmap structure - one per mddev */struct bitmap { 	struct bitmap_counts {		spinlock_t lock;		struct bitmap_page *bp;		unsigned long pages;		/* total number of pages						 * in the bitmap */		unsigned long missing_pages;	/* number of pages						 * not yet allocated */		unsigned long chunkshift;	/* chunksize = 2^chunkshift						 * (for bitops) */		unsigned long chunks;		/* Total number of data						 * chunks for the array */	} counts; 	struct mddev *mddev; /* the md device that the bitmap is for */ 	__u64	events_cleared;	int need_sync; 	struct bitmap_storage {		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 bytes;		/* total bytes in the bitmap */	} storage; 	unsigned long flags; 	int allclean; 	atomic_t behind_writes;	unsigned long behind_writes_used; /* highest actual value at runtime */ 	/*	 * 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 last_end_sync; /* when we lasted called end_sync to				      * update bitmap with resync progress */ 	atomic_t pending_writes; /* pending writes to the bitmap file */	wait_queue_head_t write_wait;	wait_queue_head_t overflow_wait;	wait_queue_head_t behind_wait; 	struct sysfs_dirent *sysfs_can_clear;}; /* the bitmap API */ /* these are used only by md/bitmap */int  bitmap_create(struct mddev *mddev);int bitmap_load(struct mddev *mddev);void bitmap_flush(struct mddev *mddev);void bitmap_destroy(struct mddev *mddev); void bitmap_print_sb(struct bitmap *bitmap);void bitmap_update_sb(struct bitmap *bitmap);void bitmap_status(struct seq_file *seq, struct bitmap *bitmap); int  bitmap_setallbits(struct bitmap *bitmap);void bitmap_write_all(struct bitmap *bitmap); void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e); /* 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, sector_t *blocks, int degraded);void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);void bitmap_close_sync(struct bitmap *bitmap);void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector); void bitmap_unplug(struct bitmap *bitmap);void bitmap_daemon_work(struct mddev *mddev); int bitmap_resize(struct bitmap *bitmap, sector_t blocks,		  int chunksize, int init);#endif #endif