| /* |
| * 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_WRITE_ERROR = 0x004, /* A write error has occurred */ |
| BITMAP_HOSTENDIAN = 0x8000, |
| }; |
| |
| /* 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 */ |
| |
| __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? */ |
| |
| atomic_t pending_writes; /* pending writes to the bitmap file */ |
| wait_queue_head_t write_wait; |
| |
| }; |
| |
| /* 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); |
| |
| 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, 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 |