/* SPDX-License-Identifier: GPL-2.0 */ /* * bitmap.h: Copyright (C) Peter T. Breuer ([email protected]) 2003 * * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc. */ #ifndef BITMAP_H #define BITMAP_H … #define BITMAP_MAJOR_LO … /* version 4 insists the bitmap is in little-endian order * with version 3, it is host-endian which is non-portable * Version 5 is currently set only for clustered devices */ #define BITMAP_MAJOR_HI … #define BITMAP_MAJOR_CLUSTERED … #define BITMAP_MAJOR_HOSTENDIAN … /* * 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 stripe is clean * Anything that dirties the stripe 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 … #define PAGE_BIT_SHIFT … bitmap_counter_t; #define COUNTER_BITS … #define COUNTER_BIT_SHIFT … #define COUNTER_BYTE_SHIFT … #define NEEDED_MASK … #define RESYNC_MASK … #define COUNTER_MAX … #define NEEDED(x) … #define RESYNC(x) … #define COUNTER(x) … /* how many counters per page? */ #define PAGE_COUNTER_RATIO … /* same, except a shift value for more efficient bitops */ #define PAGE_COUNTER_SHIFT … /* same, except a mask value for more efficient bitops */ #define PAGE_COUNTER_MASK … #define BITMAP_BLOCK_SHIFT … #endif /* * bitmap structures: */ #define BITMAP_MAGIC … /* use these for bitmap->flags and bitmap->sb->state bit-fields */ enum bitmap_state { … }; /* the superblock at the front of the bitmap file -- little endian */ 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 { … }; /* the main bitmap structure - one per mddev */ struct bitmap { … }; /* the bitmap API */ /* these are used only by md/bitmap */ struct bitmap *md_bitmap_create(struct mddev *mddev, int slot); int md_bitmap_load(struct mddev *mddev); void md_bitmap_flush(struct mddev *mddev); void md_bitmap_destroy(struct mddev *mddev); void md_bitmap_print_sb(struct bitmap *bitmap); void md_bitmap_update_sb(struct bitmap *bitmap); void md_bitmap_status(struct seq_file *seq, struct bitmap *bitmap); int md_bitmap_setallbits(struct bitmap *bitmap); void md_bitmap_write_all(struct bitmap *bitmap); void md_bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e); /* these are exported */ int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind); void md_bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int success, int behind); int md_bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded); void md_bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted); void md_bitmap_close_sync(struct bitmap *bitmap); void md_bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force); void md_bitmap_sync_with_cluster(struct mddev *mddev, sector_t old_lo, sector_t old_hi, sector_t new_lo, sector_t new_hi); void md_bitmap_unplug(struct bitmap *bitmap); void md_bitmap_unplug_async(struct bitmap *bitmap); void md_bitmap_daemon_work(struct mddev *mddev); int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, int chunksize, int init); struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot); int md_bitmap_copy_from_slot(struct mddev *mddev, int slot, sector_t *lo, sector_t *hi, bool clear_bits); void md_bitmap_free(struct bitmap *bitmap); void md_bitmap_wait_behind_writes(struct mddev *mddev); static inline bool md_bitmap_enabled(struct bitmap *bitmap) { … } #endif #endif
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