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 | /* |
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 | */ |
71 | void *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 | */ |
78 | void *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 | */ |
86 | void 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 | */ |
93 | void 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 | */ |
103 | void 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 | */ |
111 | void 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 | */ |
117 | void 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 | */ |
123 | int 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 | */ |
128 | int dm_bufio_issue_flush(struct dm_bufio_client *c); |
129 | |
130 | /* |
131 | * Send a discard request to the underlying device. |
132 | */ |
133 | int 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 | */ |
140 | void 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 | */ |
147 | void 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 | */ |
152 | void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n); |
153 | |
154 | unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c); |
155 | sector_t dm_bufio_get_device_size(struct dm_bufio_client *c); |
156 | struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c); |
157 | sector_t dm_bufio_get_block_number(struct dm_buffer *b); |
158 | void *dm_bufio_get_block_data(struct dm_buffer *b); |
159 | void *dm_bufio_get_aux_data(struct dm_buffer *b); |
160 | struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b); |
161 | |
162 | /*----------------------------------------------------------------*/ |
163 | |
164 | #endif |
165 | |