1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2009-2011 Red Hat, Inc.
4 *
5 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 *
7 * This file is released under the GPL.
8 */
9
10#ifndef _LINUX_DM_BUFIO_H
11#define _LINUX_DM_BUFIO_H
12
13#include <linux/blkdev.h>
14#include <linux/types.h>
15
16/*----------------------------------------------------------------*/
17
18struct dm_bufio_client;
19struct dm_buffer;
20
21/*
22 * Flags for dm_bufio_client_create
23 */
24#define DM_BUFIO_CLIENT_NO_SLEEP 0x1
25
26/*
27 * Create a buffered IO cache on a given device
28 */
29struct dm_bufio_client *
30dm_bufio_client_create(struct block_device *bdev, unsigned int block_size,
31 unsigned int reserved_buffers, unsigned int aux_size,
32 void (*alloc_callback)(struct dm_buffer *),
33 void (*write_callback)(struct dm_buffer *),
34 unsigned int flags);
35
36/*
37 * Release a buffered IO cache.
38 */
39void dm_bufio_client_destroy(struct dm_bufio_client *c);
40
41void dm_bufio_client_reset(struct dm_bufio_client *c);
42
43/*
44 * Set the sector range.
45 * When this function is called, there must be no I/O in progress on the bufio
46 * client.
47 */
48void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start);
49
50/*
51 * WARNING: to avoid deadlocks, these conditions are observed:
52 *
53 * - At most one thread can hold at most "reserved_buffers" simultaneously.
54 * - Each other threads can hold at most one buffer.
55 * - Threads which call only dm_bufio_get can hold unlimited number of
56 * buffers.
57 */
58
59/*
60 * Read a given block from disk. Returns pointer to data. Returns a
61 * pointer to dm_buffer that can be used to release the buffer or to make
62 * it dirty.
63 */
64void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
65 struct dm_buffer **bp);
66
67/*
68 * Like dm_bufio_read, but return buffer from cache, don't read
69 * it. If the buffer is not in the cache, return NULL.
70 */
71void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
72 struct dm_buffer **bp);
73
74/*
75 * Like dm_bufio_read, but don't read anything from the disk. It is
76 * expected that the caller initializes the buffer and marks it dirty.
77 */
78void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
79 struct dm_buffer **bp);
80
81/*
82 * Prefetch the specified blocks to the cache.
83 * The function starts to read the blocks and returns without waiting for
84 * I/O to finish.
85 */
86void dm_bufio_prefetch(struct dm_bufio_client *c,
87 sector_t block, unsigned int n_blocks);
88
89/*
90 * Release a reference obtained with dm_bufio_{read,get,new}. The data
91 * pointer and dm_buffer pointer is no longer valid after this call.
92 */
93void dm_bufio_release(struct dm_buffer *b);
94
95/*
96 * Mark a buffer dirty. It should be called after the buffer is modified.
97 *
98 * In case of memory pressure, the buffer may be written after
99 * dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So
100 * dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but
101 * the actual writing may occur earlier.
102 */
103void dm_bufio_mark_buffer_dirty(struct dm_buffer *b);
104
105/*
106 * Mark a part of the buffer dirty.
107 *
108 * The specified part of the buffer is scheduled to be written. dm-bufio may
109 * write the specified part of the buffer or it may write a larger superset.
110 */
111void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
112 unsigned int start, unsigned int end);
113
114/*
115 * Initiate writing of dirty buffers, without waiting for completion.
116 */
117void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c);
118
119/*
120 * Write all dirty buffers. Guarantees that all dirty buffers created prior
121 * to this call are on disk when this call exits.
122 */
123int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c);
124
125/*
126 * Send an empty write barrier to the device to flush hardware disk cache.
127 */
128int dm_bufio_issue_flush(struct dm_bufio_client *c);
129
130/*
131 * Send a discard request to the underlying device.
132 */
133int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count);
134
135/*
136 * Free the given buffer.
137 * This is just a hint, if the buffer is in use or dirty, this function
138 * does nothing.
139 */
140void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);
141
142/*
143 * Free the given range of buffers.
144 * This is just a hint, if the buffer is in use or dirty, this function
145 * does nothing.
146 */
147void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks);
148
149/*
150 * Set the minimum number of buffers before cleanup happens.
151 */
152void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n);
153
154unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c);
155sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
156struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c);
157sector_t dm_bufio_get_block_number(struct dm_buffer *b);
158void *dm_bufio_get_block_data(struct dm_buffer *b);
159void *dm_bufio_get_aux_data(struct dm_buffer *b);
160struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b);
161
162/*----------------------------------------------------------------*/
163
164#endif
165

source code of linux/include/linux/dm-bufio.h