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/*
* Copyright (C) 2009-2011 Red Hat, Inc.
*
* Author: Mikulas Patocka <mpatocka@redhat.com>
*
* This file is released under the GPL.
*/
#ifndef DM_BUFIO_H
#define DM_BUFIO_H
#include <linux/blkdev.h>
#include <linux/types.h>
/*----------------------------------------------------------------*/
struct dm_bufio_client;
struct dm_buffer;
/*
* Create a buffered IO cache on a given device
*/
struct dm_bufio_client *
dm_bufio_client_create(struct block_device *bdev, unsigned block_size,
unsigned reserved_buffers, unsigned aux_size,
void (*alloc_callback)(struct dm_buffer *),
void (*write_callback)(struct dm_buffer *));
/*
* Release a buffered IO cache.
*/
void dm_bufio_client_destroy(struct dm_bufio_client *c);
/*
* WARNING: to avoid deadlocks, these conditions are observed:
*
* - At most one thread can hold at most "reserved_buffers" simultaneously.
* - Each other threads can hold at most one buffer.
* - Threads which call only dm_bufio_get can hold unlimited number of
* buffers.
*/
/*
* Read a given block from disk. Returns pointer to data. Returns a
* pointer to dm_buffer that can be used to release the buffer or to make
* it dirty.
*/
void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
struct dm_buffer **bp);
/*
* Like dm_bufio_read, but return buffer from cache, don't read
* it. If the buffer is not in the cache, return NULL.
*/
void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
struct dm_buffer **bp);
/*
* Like dm_bufio_read, but don't read anything from the disk. It is
* expected that the caller initializes the buffer and marks it dirty.
*/
void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
struct dm_buffer **bp);
/*
* Prefetch the specified blocks to the cache.
* The function starts to read the blocks and returns without waiting for
* I/O to finish.
*/
void dm_bufio_prefetch(struct dm_bufio_client *c,
sector_t block, unsigned n_blocks);
/*
* Release a reference obtained with dm_bufio_{read,get,new}. The data
* pointer and dm_buffer pointer is no longer valid after this call.
*/
void dm_bufio_release(struct dm_buffer *b);
/*
* Mark a buffer dirty. It should be called after the buffer is modified.
*
* In case of memory pressure, the buffer may be written after
* dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So
* dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but
* the actual writing may occur earlier.
*/
void dm_bufio_mark_buffer_dirty(struct dm_buffer *b);
/*
* Initiate writing of dirty buffers, without waiting for completion.
*/
void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c);
/*
* Write all dirty buffers. Guarantees that all dirty buffers created prior
* to this call are on disk when this call exits.
*/
int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c);
/*
* Send an empty write barrier to the device to flush hardware disk cache.
*/
int dm_bufio_issue_flush(struct dm_bufio_client *c);
/*
* Like dm_bufio_release but also move the buffer to the new
* block. dm_bufio_write_dirty_buffers is needed to commit the new block.
*/
void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block);
/*
* Free the given buffer.
* This is just a hint, if the buffer is in use or dirty, this function
* does nothing.
*/
void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);
/*
* Set the minimum number of buffers before cleanup happens.
*/
void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n);
unsigned dm_bufio_get_block_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_block_number(struct dm_buffer *b);
void *dm_bufio_get_block_data(struct dm_buffer *b);
void *dm_bufio_get_aux_data(struct dm_buffer *b);
struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b);
/*----------------------------------------------------------------*/
#endif
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