275 lines
9.7 KiB
C
275 lines
9.7 KiB
C
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/*
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* bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
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*
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* additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
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*/
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#ifndef BITMAP_H
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#define BITMAP_H 1
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#define BITMAP_MAJOR_LO 3
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/* version 4 insists the bitmap is in little-endian order
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* with version 3, it is host-endian which is non-portable
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* Version 5 is currently set only for clustered devices
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*/
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#define BITMAP_MAJOR_HI 4
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#define BITMAP_MAJOR_CLUSTERED 5
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#define BITMAP_MAJOR_HOSTENDIAN 3
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/*
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* in-memory bitmap:
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*
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* Use 16 bit block counters to track pending writes to each "chunk".
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* The 2 high order bits are special-purpose, the first is a flag indicating
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* whether a resync is needed. The second is a flag indicating whether a
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* resync is active.
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* This means that the counter is actually 14 bits:
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*
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* +--------+--------+------------------------------------------------+
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* | resync | resync | counter |
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* | needed | active | |
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* | (0-1) | (0-1) | (0-16383) |
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* +--------+--------+------------------------------------------------+
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*
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* The "resync needed" bit is set when:
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* a '1' bit is read from storage at startup.
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* a write request fails on some drives
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* a resync is aborted on a chunk with 'resync active' set
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* It is cleared (and resync-active set) when a resync starts across all drives
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* of the chunk.
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*
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*
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* The "resync active" bit is set when:
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* a resync is started on all drives, and resync_needed is set.
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* resync_needed will be cleared (as long as resync_active wasn't already set).
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* It is cleared when a resync completes.
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*
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* The counter counts pending write requests, plus the on-disk bit.
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* When the counter is '1' and the resync bits are clear, the on-disk
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* bit can be cleared as well, thus setting the counter to 0.
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* When we set a bit, or in the counter (to start a write), if the fields is
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* 0, we first set the disk bit and set the counter to 1.
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*
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* If the counter is 0, the on-disk bit is clear and the stripe is clean
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* Anything that dirties the stripe pushes the counter to 2 (at least)
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* and sets the on-disk bit (lazily).
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* If a periodic sweep find the counter at 2, it is decremented to 1.
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* If the sweep find the counter at 1, the on-disk bit is cleared and the
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* counter goes to zero.
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*
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* Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
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* counters as a fallback when "page" memory cannot be allocated:
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*
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* Normal case (page memory allocated):
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*
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* page pointer (32-bit)
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*
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* [ ] ------+
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* |
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* +-------> [ ][ ]..[ ] (4096 byte page == 2048 counters)
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* c1 c2 c2048
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*
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* Hijacked case (page memory allocation failed):
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*
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* hijacked page pointer (32-bit)
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*
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* [ ][ ] (no page memory allocated)
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* counter #1 (16-bit) counter #2 (16-bit)
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*
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*/
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#ifdef __KERNEL__
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#define PAGE_BITS (PAGE_SIZE << 3)
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#define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)
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typedef __u16 bitmap_counter_t;
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#define COUNTER_BITS 16
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#define COUNTER_BIT_SHIFT 4
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#define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3)
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#define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1)))
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#define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2)))
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#define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1)
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#define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK)
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#define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK)
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#define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX)
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/* how many counters per page? */
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#define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS)
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/* same, except a shift value for more efficient bitops */
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#define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT)
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/* same, except a mask value for more efficient bitops */
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#define PAGE_COUNTER_MASK (PAGE_COUNTER_RATIO - 1)
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#define BITMAP_BLOCK_SHIFT 9
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#endif
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/*
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* bitmap structures:
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*/
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#define BITMAP_MAGIC 0x6d746962
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/* use these for bitmap->flags and bitmap->sb->state bit-fields */
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enum bitmap_state {
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BITMAP_STALE = 1, /* the bitmap file is out of date or had -EIO */
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BITMAP_WRITE_ERROR = 2, /* A write error has occurred */
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BITMAP_HOSTENDIAN =15,
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};
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/* the superblock at the front of the bitmap file -- little endian */
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typedef struct bitmap_super_s {
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__le32 magic; /* 0 BITMAP_MAGIC */
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__le32 version; /* 4 the bitmap major for now, could change... */
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__u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */
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__le64 events; /* 24 event counter for the bitmap (1)*/
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__le64 events_cleared;/*32 event counter when last bit cleared (2) */
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__le64 sync_size; /* 40 the size of the md device's sync range(3) */
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__le32 state; /* 48 bitmap state information */
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__le32 chunksize; /* 52 the bitmap chunk size in bytes */
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__le32 daemon_sleep; /* 56 seconds between disk flushes */
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__le32 write_behind; /* 60 number of outstanding write-behind writes */
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__le32 sectors_reserved; /* 64 number of 512-byte sectors that are
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* reserved for the bitmap. */
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__le32 nodes; /* 68 the maximum number of nodes in cluster. */
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__u8 cluster_name[64]; /* 72 cluster name to which this md belongs */
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__u8 pad[256 - 136]; /* set to zero */
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} bitmap_super_t;
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/* notes:
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* (1) This event counter is updated before the eventcounter in the md superblock
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* When a bitmap is loaded, it is only accepted if this event counter is equal
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* to, or one greater than, the event counter in the superblock.
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* (2) This event counter is updated when the other one is *if*and*only*if* the
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* array is not degraded. As bits are not cleared when the array is degraded,
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* this represents the last time that any bits were cleared.
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* If a device is being added that has an event count with this value or
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* higher, it is accepted as conforming to the bitmap.
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* (3)This is the number of sectors represented by the bitmap, and is the range that
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* resync happens across. For raid1 and raid5/6 it is the size of individual
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* devices. For raid10 it is the size of the array.
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*/
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#ifdef __KERNEL__
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/* the in-memory bitmap is represented by bitmap_pages */
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struct bitmap_page {
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/*
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* map points to the actual memory page
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*/
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char *map;
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/*
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* in emergencies (when map cannot be alloced), hijack the map
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* pointer and use it as two counters itself
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*/
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unsigned int hijacked:1;
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/*
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* If any counter in this page is '1' or '2' - and so could be
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* cleared then that page is marked as 'pending'
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*/
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unsigned int pending:1;
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/*
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* count of dirty bits on the page
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*/
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unsigned int count:30;
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};
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/* the main bitmap structure - one per mddev */
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struct bitmap {
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struct bitmap_counts {
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spinlock_t lock;
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struct bitmap_page *bp;
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unsigned long pages; /* total number of pages
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* in the bitmap */
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unsigned long missing_pages; /* number of pages
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* not yet allocated */
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unsigned long chunkshift; /* chunksize = 2^chunkshift
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* (for bitops) */
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unsigned long chunks; /* Total number of data
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* chunks for the array */
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} counts;
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struct mddev *mddev; /* the md device that the bitmap is for */
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__u64 events_cleared;
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int need_sync;
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struct bitmap_storage {
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struct file *file; /* backing disk file */
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struct page *sb_page; /* cached copy of the bitmap
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* file superblock */
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struct page **filemap; /* list of cache pages for
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* the file */
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unsigned long *filemap_attr; /* attributes associated
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* w/ filemap pages */
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unsigned long file_pages; /* number of pages in the file*/
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unsigned long bytes; /* total bytes in the bitmap */
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} storage;
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unsigned long flags;
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int allclean;
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atomic_t behind_writes;
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unsigned long behind_writes_used; /* highest actual value at runtime */
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/*
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* the bitmap daemon - periodically wakes up and sweeps the bitmap
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* file, cleaning up bits and flushing out pages to disk as necessary
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*/
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unsigned long daemon_lastrun; /* jiffies of last run */
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unsigned long last_end_sync; /* when we lasted called end_sync to
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* update bitmap with resync progress */
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atomic_t pending_writes; /* pending writes to the bitmap file */
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wait_queue_head_t write_wait;
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wait_queue_head_t overflow_wait;
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wait_queue_head_t behind_wait;
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struct kernfs_node *sysfs_can_clear;
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int cluster_slot; /* Slot offset for clustered env */
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};
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/* the bitmap API */
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/* these are used only by md/bitmap */
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struct bitmap *bitmap_create(struct mddev *mddev, int slot);
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int bitmap_load(struct mddev *mddev);
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void bitmap_flush(struct mddev *mddev);
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void bitmap_destroy(struct mddev *mddev);
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void bitmap_print_sb(struct bitmap *bitmap);
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void bitmap_update_sb(struct bitmap *bitmap);
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void bitmap_status(struct seq_file *seq, struct bitmap *bitmap);
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int bitmap_setallbits(struct bitmap *bitmap);
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void bitmap_write_all(struct bitmap *bitmap);
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void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
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/* these are exported */
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int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
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unsigned long sectors, int behind);
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void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
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unsigned long sectors, int success, int behind);
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int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);
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void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);
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void bitmap_close_sync(struct bitmap *bitmap);
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void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force);
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void bitmap_sync_with_cluster(struct mddev *mddev,
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sector_t old_lo, sector_t old_hi,
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sector_t new_lo, sector_t new_hi);
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void bitmap_unplug(struct bitmap *bitmap);
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void bitmap_daemon_work(struct mddev *mddev);
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int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
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int chunksize, int init);
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int bitmap_copy_from_slot(struct mddev *mddev, int slot,
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sector_t *lo, sector_t *hi, bool clear_bits);
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#endif
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#endif
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