2 * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 /** @addtogroup lwext4
34 * @brief Block cache allocator.
37 #ifndef EXT4_BCACHE_H_
38 #define EXT4_BCACHE_H_
44 #include "ext4_config.h"
51 #define EXT4_BLOCK_ZERO() \
52 {.uptodate = 0, .dirty = 0, .lb_id = 0, .data = 0}
54 /**@brief Single block descriptor*/
56 /**@brief Uptodate flag*/
59 /**@brief Dirty flag*/
62 /**@brief Logical block ID*/
68 /**@brief Data buffer.*/
72 /**@brief Single block descriptor*/
77 /**@brief Logical block address*/
80 /**@brief Data buffer.*/
83 /**@brief LRU priority. (unused) */
89 /**@brief Reference count table*/
92 /**@brief LBA tree node*/
93 RB_ENTRY(ext4_buf) lba_node;
95 /**@brief LRU tree node*/
96 RB_ENTRY(ext4_buf) lru_node;
98 /**@brief Dirty list node*/
99 SLIST_ENTRY(ext4_buf) dirty_node;
102 /**@brief Block cache descriptor*/
105 /**@brief Item count in block cache*/
108 /**@brief Item size in block cache*/
111 /**@brief Last recently used counter*/
114 /**@brief Writeback free delay mode*/
117 /**@brief Currently referenced datablocks*/
120 /**@brief Maximum referenced datablocks*/
121 uint32_t max_ref_blocks;
123 /**@brief A tree holding all bufs*/
124 RB_HEAD(ext4_buf_lba, ext4_buf) lba_root;
126 /**@brief A tree holding unreferenced bufs*/
127 RB_HEAD(ext4_buf_lru, ext4_buf) lru_root;
129 /**@brief A singly-linked list holding dirty buffers*/
130 SLIST_HEAD(ext4_buf_dirty, ext4_buf) dirty_list;
133 enum bcache_state_bits {
138 #define ext4_bcache_set_flag(buf, b) \
139 (buf)->flags |= 1 << (b)
141 #define ext4_bcache_clear_flag(buf, b) \
142 (buf)->flags &= ~(1 << (b))
144 #define ext4_bcache_test_flag(buf, b) \
145 (((buf)->flags & (1 << (b))) >> (b))
147 /**@brief Static initializer of block cache structure.*/
148 #define EXT4_BCACHE_STATIC_INSTANCE(__name, __cnt, __itemsize) \
149 static struct ext4_bcache __name = { \
151 .itemsize = __itemsize, \
155 /**@brief Dynamic initialization of block cache.
156 * @param bc block cache descriptor
157 * @param cnt items count in block cache
158 * @param itemsize single item size (in bytes)
159 * @return standard error code*/
160 int ext4_bcache_init_dynamic(struct ext4_bcache *bc, uint32_t cnt,
163 /**@brief Dynamic de-initialization of block cache.
164 * @param bc block cache descriptor
165 * @return standard error code*/
166 int ext4_bcache_fini_dynamic(struct ext4_bcache *bc);
168 /**@brief Get a buffer with the lowest LRU counter in bcache.
169 * @param bc block cache descriptor
170 * @return buffer with the lowest LRU counter*/
171 struct ext4_buf *ext4_buf_lowest_lru(struct ext4_bcache *bc);
173 /**@brief Drop unreferenced buffer from bcache.
174 * @param bc block cache descriptor
175 * @param buf buffer*/
176 void ext4_bcache_drop_buf(struct ext4_bcache *bc, struct ext4_buf *buf);
178 /**@brief Allocate block from block cache memory.
179 * Unreferenced block allocation is based on LRU
180 * (Last Recently Used) algorithm.
181 * @param bc block cache descriptor
182 * @param b block to alloc
183 * @param is_new block is new (needs to be read)
184 * @return standard error code*/
185 int ext4_bcache_alloc(struct ext4_bcache *bc, struct ext4_block *b,
188 /**@brief Free block from cache memory (decrement reference counter).
189 * @param bc block cache descriptor
190 * @param b block to free
191 * @param cache writeback mode
192 * @return standard error code*/
193 int ext4_bcache_free(struct ext4_bcache *bc, struct ext4_block *b,
196 /**@brief Return a full status of block cache.
197 * @param bc block cache descriptor
198 * @return full status*/
199 bool ext4_bcache_is_full(struct ext4_bcache *bc);
205 #endif /* EXT4_BCACHE_H_ */