summaryrefslogtreecommitdiff
path: root/include/linux/dm-bufio.h
blob: 681656a1c03d0a86429622822fcab8af827e0d4c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2009-2011 Red Hat, Inc.
 *
 * Author: Mikulas Patocka <mpatocka@redhat.com>
 *
 * This file is released under the GPL.
 */

#ifndef _LINUX_DM_BUFIO_H
#define _LINUX_DM_BUFIO_H

#include <linux/blkdev.h>
#include <linux/types.h>

/*----------------------------------------------------------------*/

struct dm_bufio_client;
struct dm_buffer;

/*
 * Flags for dm_bufio_client_create
 */
#define DM_BUFIO_CLIENT_NO_SLEEP 0x1

/*
 * Create a buffered IO cache on a given device
 */
struct dm_bufio_client *
dm_bufio_client_create(struct block_device *bdev, unsigned int block_size,
		       unsigned int reserved_buffers, unsigned int aux_size,
		       void (*alloc_callback)(struct dm_buffer *),
		       void (*write_callback)(struct dm_buffer *),
		       unsigned int flags);

/*
 * Release a buffered IO cache.
 */
void dm_bufio_client_destroy(struct dm_bufio_client *c);

/*
 * Set the sector range.
 * When this function is called, there must be no I/O in progress on the bufio
 * client.
 */
void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start);

/*
 * 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 int 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);

/*
 * Mark a part of the buffer dirty.
 *
 * The specified part of the buffer is scheduled to be written. dm-bufio may
 * write the specified part of the buffer or it may write a larger superset.
 */
void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
					unsigned int start, unsigned int end);

/*
 * 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);

/*
 * Send a discard request to the underlying device.
 */
int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count);

/*
 * 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);

/*
 * Free the given range of buffers.
 * This is just a hint, if the buffer is in use or dirty, this function
 * does nothing.
 */
void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks);

/*
 * Set the minimum number of buffers before cleanup happens.
 */
void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n);

unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
struct dm_io_client *dm_bufio_get_dm_io_client(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