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
18 struct dm_bufio_client;
19 struct 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 */
29 struct dm_bufio_client *
30 dm_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 */
39 void dm_bufio_client_destroy(struct dm_bufio_client *c);
40
41 void 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 */
48 void 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 */
64 void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
65 struct dm_buffer **bp);
66
67 void *dm_bufio_read_with_ioprio(struct dm_bufio_client *c, sector_t block,
68 struct dm_buffer **bp, unsigned short ioprio);
69
70 /*
71 * Like dm_bufio_read, but return buffer from cache, don't read
72 * it. If the buffer is not in the cache, return NULL.
73 */
74 void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
75 struct dm_buffer **bp);
76
77 /*
78 * Like dm_bufio_read, but don't read anything from the disk. It is
79 * expected that the caller initializes the buffer and marks it dirty.
80 */
81 void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
82 struct dm_buffer **bp);
83
84 /*
85 * Prefetch the specified blocks to the cache.
86 * The function starts to read the blocks and returns without waiting for
87 * I/O to finish.
88 */
89 void dm_bufio_prefetch(struct dm_bufio_client *c,
90 sector_t block, unsigned int n_blocks);
91
92 void dm_bufio_prefetch_with_ioprio(struct dm_bufio_client *c,
93 sector_t block, unsigned int n_blocks,
94 unsigned short ioprio);
95
96 /*
97 * Release a reference obtained with dm_bufio_{read,get,new}. The data
98 * pointer and dm_buffer pointer is no longer valid after this call.
99 */
100 void dm_bufio_release(struct dm_buffer *b);
101
102 /*
103 * Mark a buffer dirty. It should be called after the buffer is modified.
104 *
105 * In case of memory pressure, the buffer may be written after
106 * dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So
107 * dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but
108 * the actual writing may occur earlier.
109 */
110 void dm_bufio_mark_buffer_dirty(struct dm_buffer *b);
111
112 /*
113 * Mark a part of the buffer dirty.
114 *
115 * The specified part of the buffer is scheduled to be written. dm-bufio may
116 * write the specified part of the buffer or it may write a larger superset.
117 */
118 void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
119 unsigned int start, unsigned int end);
120
121 /*
122 * Initiate writing of dirty buffers, without waiting for completion.
123 */
124 void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c);
125
126 /*
127 * Write all dirty buffers. Guarantees that all dirty buffers created prior
128 * to this call are on disk when this call exits.
129 */
130 int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c);
131
132 /*
133 * Send an empty write barrier to the device to flush hardware disk cache.
134 */
135 int dm_bufio_issue_flush(struct dm_bufio_client *c);
136
137 /*
138 * Send a discard request to the underlying device.
139 */
140 int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count);
141
142 /*
143 * Free the given buffer.
144 * This is just a hint, if the buffer is in use or dirty, this function
145 * does nothing.
146 */
147 void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);
148
149 /*
150 * Free the given range of buffers.
151 * This is just a hint, if the buffer is in use or dirty, this function
152 * does nothing.
153 */
154 void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks);
155
156 /*
157 * Set the minimum number of buffers before cleanup happens.
158 */
159 void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n);
160
161 unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c);
162 sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
163 struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c);
164 sector_t dm_bufio_get_block_number(struct dm_buffer *b);
165 void *dm_bufio_get_block_data(struct dm_buffer *b);
166 void *dm_bufio_get_aux_data(struct dm_buffer *b);
167 struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b);
168
169 /*----------------------------------------------------------------*/
170
171 #endif
172
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