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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - drivers/md/dm-bufio.h
2 * Copyright (C) 2009-2011 Red Hat, Inc.
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 * This file is released under the GPL.
12 #include <linux/blkdev.h>
13 #include <linux/types.h>
15 /*----------------------------------------------------------------*/
17 struct dm_bufio_client
;
21 * Create a buffered IO cache on a given device
23 struct dm_bufio_client
*
24 dm_bufio_client_create(struct block_device
*bdev
, unsigned block_size
,
25 unsigned reserved_buffers
, unsigned aux_size
,
26 void (*alloc_callback
)(struct dm_buffer
*),
27 void (*write_callback
)(struct dm_buffer
*));
30 * Release a buffered IO cache.
32 void dm_bufio_client_destroy(struct dm_bufio_client
*c
);
35 * Set the sector range.
36 * When this function is called, there must be no I/O in progress on the bufio
39 void dm_bufio_set_sector_offset(struct dm_bufio_client
*c
, sector_t start
);
42 * WARNING: to avoid deadlocks, these conditions are observed:
44 * - At most one thread can hold at most "reserved_buffers" simultaneously.
45 * - Each other threads can hold at most one buffer.
46 * - Threads which call only dm_bufio_get can hold unlimited number of
51 * Read a given block from disk. Returns pointer to data. Returns a
52 * pointer to dm_buffer that can be used to release the buffer or to make
55 void *dm_bufio_read(struct dm_bufio_client
*c
, sector_t block
,
56 struct dm_buffer
**bp
);
59 * Like dm_bufio_read, but return buffer from cache, don't read
60 * it. If the buffer is not in the cache, return NULL.
62 void *dm_bufio_get(struct dm_bufio_client
*c
, sector_t block
,
63 struct dm_buffer
**bp
);
66 * Like dm_bufio_read, but don't read anything from the disk. It is
67 * expected that the caller initializes the buffer and marks it dirty.
69 void *dm_bufio_new(struct dm_bufio_client
*c
, sector_t block
,
70 struct dm_buffer
**bp
);
73 * Prefetch the specified blocks to the cache.
74 * The function starts to read the blocks and returns without waiting for
77 void dm_bufio_prefetch(struct dm_bufio_client
*c
,
78 sector_t block
, unsigned n_blocks
);
81 * Release a reference obtained with dm_bufio_{read,get,new}. The data
82 * pointer and dm_buffer pointer is no longer valid after this call.
84 void dm_bufio_release(struct dm_buffer
*b
);
87 * Mark a buffer dirty. It should be called after the buffer is modified.
89 * In case of memory pressure, the buffer may be written after
90 * dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So
91 * dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but
92 * the actual writing may occur earlier.
94 void dm_bufio_mark_buffer_dirty(struct dm_buffer
*b
);
97 * Initiate writing of dirty buffers, without waiting for completion.
99 void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client
*c
);
102 * Write all dirty buffers. Guarantees that all dirty buffers created prior
103 * to this call are on disk when this call exits.
105 int dm_bufio_write_dirty_buffers(struct dm_bufio_client
*c
);
108 * Send an empty write barrier to the device to flush hardware disk cache.
110 int dm_bufio_issue_flush(struct dm_bufio_client
*c
);
113 * Like dm_bufio_release but also move the buffer to the new
114 * block. dm_bufio_write_dirty_buffers is needed to commit the new block.
116 void dm_bufio_release_move(struct dm_buffer
*b
, sector_t new_block
);
119 * Free the given buffer.
120 * This is just a hint, if the buffer is in use or dirty, this function
123 void dm_bufio_forget(struct dm_bufio_client
*c
, sector_t block
);
126 * Set the minimum number of buffers before cleanup happens.
128 void dm_bufio_set_minimum_buffers(struct dm_bufio_client
*c
, unsigned n
);
130 unsigned dm_bufio_get_block_size(struct dm_bufio_client
*c
);
131 sector_t
dm_bufio_get_device_size(struct dm_bufio_client
*c
);
132 sector_t
dm_bufio_get_block_number(struct dm_buffer
*b
);
133 void *dm_bufio_get_block_data(struct dm_buffer
*b
);
134 void *dm_bufio_get_aux_data(struct dm_buffer
*b
);
135 struct dm_bufio_client
*dm_bufio_get_client(struct dm_buffer
*b
);
137 /*----------------------------------------------------------------*/