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
67void *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 */
74void *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 */
81void *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 */
89void dm_bufio_prefetch(struct dm_bufio_client *c,
90		       sector_t block, unsigned int n_blocks);
91
92void 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 */
100void 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 */
110void 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 */
118void 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 */
124void 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 */
130int 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 */
135int dm_bufio_issue_flush(struct dm_bufio_client *c);
136
137/*
138 * Send a discard request to the underlying device.
139 */
140int 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 */
147void 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 */
154void 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 */
159void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n);
160
161unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c);
162sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
163struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c);
164sector_t dm_bufio_get_block_number(struct dm_buffer *b);
165void *dm_bufio_get_block_data(struct dm_buffer *b);
166void *dm_bufio_get_aux_data(struct dm_buffer *b);
167struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b);
168
169/*----------------------------------------------------------------*/
170
171#endif
172