http://www.ousob.com --- Legacy Redefined OuSob - File: /wwwroot/clipx/usr/include/linux/raid/bitmap.h

/* * 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