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95d402f0 MP |
1 | /* |
2 | * Copyright (C) 2009-2011 Red Hat, Inc. | |
3 | * | |
4 | * Author: Mikulas Patocka <mpatocka@redhat.com> | |
5 | * | |
6 | * This file is released under the GPL. | |
7 | */ | |
8 | ||
9 | #ifndef DM_BUFIO_H | |
10 | #define DM_BUFIO_H | |
11 | ||
12 | #include <linux/blkdev.h> | |
13 | #include <linux/types.h> | |
14 | ||
15 | /*----------------------------------------------------------------*/ | |
16 | ||
17 | struct dm_bufio_client; | |
18 | struct dm_buffer; | |
19 | ||
20 | /* | |
21 | * Create a buffered IO cache on a given device | |
22 | */ | |
23 | struct dm_bufio_client * | |
24 | dm_bufio_client_create(struct block_device *bdev, unsigned block_size, | |
25 | unsigned reserved_buffers, unsigned aux_size, | |
26 | void (*alloc_callback)(struct dm_buffer *), | |
27 | void (*write_callback)(struct dm_buffer *)); | |
28 | ||
29 | /* | |
30 | * Release a buffered IO cache. | |
31 | */ | |
32 | void dm_bufio_client_destroy(struct dm_bufio_client *c); | |
33 | ||
34 | /* | |
35 | * WARNING: to avoid deadlocks, these conditions are observed: | |
36 | * | |
37 | * - At most one thread can hold at most "reserved_buffers" simultaneously. | |
38 | * - Each other threads can hold at most one buffer. | |
39 | * - Threads which call only dm_bufio_get can hold unlimited number of | |
40 | * buffers. | |
41 | */ | |
42 | ||
43 | /* | |
44 | * Read a given block from disk. Returns pointer to data. Returns a | |
45 | * pointer to dm_buffer that can be used to release the buffer or to make | |
46 | * it dirty. | |
47 | */ | |
48 | void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, | |
49 | struct dm_buffer **bp); | |
50 | ||
51 | /* | |
52 | * Like dm_bufio_read, but return buffer from cache, don't read | |
53 | * it. If the buffer is not in the cache, return NULL. | |
54 | */ | |
55 | void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, | |
56 | struct dm_buffer **bp); | |
57 | ||
58 | /* | |
59 | * Like dm_bufio_read, but don't read anything from the disk. It is | |
60 | * expected that the caller initializes the buffer and marks it dirty. | |
61 | */ | |
62 | void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, | |
63 | struct dm_buffer **bp); | |
64 | ||
a66cc28f MP |
65 | /* |
66 | * Prefetch the specified blocks to the cache. | |
67 | * The function starts to read the blocks and returns without waiting for | |
68 | * I/O to finish. | |
69 | */ | |
70 | void dm_bufio_prefetch(struct dm_bufio_client *c, | |
71 | sector_t block, unsigned n_blocks); | |
72 | ||
95d402f0 MP |
73 | /* |
74 | * Release a reference obtained with dm_bufio_{read,get,new}. The data | |
75 | * pointer and dm_buffer pointer is no longer valid after this call. | |
76 | */ | |
77 | void dm_bufio_release(struct dm_buffer *b); | |
78 | ||
79 | /* | |
80 | * Mark a buffer dirty. It should be called after the buffer is modified. | |
81 | * | |
82 | * In case of memory pressure, the buffer may be written after | |
83 | * dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So | |
84 | * dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but | |
85 | * the actual writing may occur earlier. | |
86 | */ | |
87 | void dm_bufio_mark_buffer_dirty(struct dm_buffer *b); | |
88 | ||
89 | /* | |
90 | * Initiate writing of dirty buffers, without waiting for completion. | |
91 | */ | |
92 | void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c); | |
93 | ||
94 | /* | |
95 | * Write all dirty buffers. Guarantees that all dirty buffers created prior | |
96 | * to this call are on disk when this call exits. | |
97 | */ | |
98 | int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c); | |
99 | ||
100 | /* | |
101 | * Send an empty write barrier to the device to flush hardware disk cache. | |
102 | */ | |
103 | int dm_bufio_issue_flush(struct dm_bufio_client *c); | |
104 | ||
105 | /* | |
106 | * Like dm_bufio_release but also move the buffer to the new | |
107 | * block. dm_bufio_write_dirty_buffers is needed to commit the new block. | |
108 | */ | |
109 | void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block); | |
110 | ||
55494bf2 MP |
111 | /* |
112 | * Free the given buffer. | |
113 | * This is just a hint, if the buffer is in use or dirty, this function | |
114 | * does nothing. | |
115 | */ | |
116 | void dm_bufio_forget(struct dm_bufio_client *c, sector_t block); | |
117 | ||
55b082e6 MP |
118 | /* |
119 | * Set the minimum number of buffers before cleanup happens. | |
120 | */ | |
121 | void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n); | |
122 | ||
95d402f0 MP |
123 | unsigned dm_bufio_get_block_size(struct dm_bufio_client *c); |
124 | sector_t dm_bufio_get_device_size(struct dm_bufio_client *c); | |
125 | sector_t dm_bufio_get_block_number(struct dm_buffer *b); | |
126 | void *dm_bufio_get_block_data(struct dm_buffer *b); | |
127 | void *dm_bufio_get_aux_data(struct dm_buffer *b); | |
128 | struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b); | |
129 | ||
130 | /*----------------------------------------------------------------*/ | |
131 | ||
132 | #endif |