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 {.lb_id = 0, .data = 0}
54 /**@brief Single block descriptor*/
56 /**@brief Logical block ID*/
62 /**@brief Data buffer.*/
68 /**@brief Single block descriptor*/
73 /**@brief Logical block address*/
76 /**@brief Data buffer.*/
79 /**@brief LRU priority. (unused) */
85 /**@brief Reference count table*/
88 /**@brief Whether or not buffer is on dirty list.*/
91 /**@brief LBA tree node*/
92 RB_ENTRY(ext4_buf) lba_node;
94 /**@brief LRU tree node*/
95 RB_ENTRY(ext4_buf) lru_node;
97 /**@brief Dirty list node*/
98 SLIST_ENTRY(ext4_buf) dirty_node;
100 /**@brief Callback routine after a disk-write operation.
101 * @param bc block cache descriptor
102 * @param buf buffer descriptor
103 * @param standard error code returned by bdev->bwrite()
104 * @param arg argument passed to this routine*/
105 void (*end_write)(struct ext4_bcache *bc,
106 struct ext4_buf *buf,
110 /**@brief argument passed to end_write() callback.*/
114 /**@brief Block cache descriptor*/
117 /**@brief Item count in block cache*/
120 /**@brief Item size in block cache*/
123 /**@brief Last recently used counter*/
126 /**@brief Currently referenced datablocks*/
129 /**@brief Maximum referenced datablocks*/
130 uint32_t max_ref_blocks;
132 /**@brief The blockdev binded to this block cache*/
133 struct ext4_blockdev *bdev;
135 /**@brief A tree holding all bufs*/
136 RB_HEAD(ext4_buf_lba, ext4_buf) lba_root;
138 /**@brief A tree holding unreferenced bufs*/
139 RB_HEAD(ext4_buf_lru, ext4_buf) lru_root;
141 /**@brief A singly-linked list holding dirty buffers*/
142 SLIST_HEAD(ext4_buf_dirty, ext4_buf) dirty_list;
145 /**@brief buffer state bits
147 * - BC♡UPTODATE: Buffer contains valid data.
148 * - BC_DIRTY: Buffer is dirty.
149 * - BC_FLUSH: Buffer will be immediately flushed,
150 * when no one references it.
152 enum bcache_state_bits {
158 #define ext4_bcache_set_flag(buf, b) \
159 (buf)->flags |= 1 << (b)
161 #define ext4_bcache_clear_flag(buf, b) \
162 (buf)->flags &= ~(1 << (b))
164 #define ext4_bcache_test_flag(buf, b) \
165 (((buf)->flags & (1 << (b))) >> (b))
167 static inline void ext4_bcache_set_dirty(struct ext4_buf *buf) {
168 ext4_bcache_set_flag(buf, BC_UPTODATE);
169 ext4_bcache_set_flag(buf, BC_DIRTY);
172 static inline void ext4_bcache_clear_dirty(struct ext4_buf *buf) {
173 ext4_bcache_clear_flag(buf, BC_UPTODATE);
174 ext4_bcache_clear_flag(buf, BC_DIRTY);
177 /**@brief Increment reference counter of buf by 1.*/
178 #define ext4_bcache_inc_ref(buf) ((buf)->refctr++)
180 /**@brief Decrement reference counter of buf by 1.*/
181 #define ext4_bcache_dec_ref(buf) ((buf)->refctr--)
183 /**@brief Static initializer of block cache structure.*/
184 #define EXT4_BCACHE_STATIC_INSTANCE(__name, __cnt, __itemsize) \
185 static struct ext4_bcache __name = { \
187 .itemsize = __itemsize, \
191 /**@brief Insert buffer to dirty cache list
192 * @param bc block cache descriptor
193 * @param buf buffer descriptor */
195 ext4_bcache_insert_dirty_node(struct ext4_bcache *bc, struct ext4_buf *buf) {
196 if (!buf->on_dirty_list) {
197 SLIST_INSERT_HEAD(&bc->dirty_list, buf, dirty_node);
198 buf->on_dirty_list = true;
202 /**@brief Remove buffer to dirty cache list
203 * @param bc block cache descriptor
204 * @param buf buffer descriptor */
206 ext4_bcache_remove_dirty_node(struct ext4_bcache *bc, struct ext4_buf *buf) {
207 if (buf->on_dirty_list) {
208 SLIST_REMOVE(&bc->dirty_list, buf, ext4_buf, dirty_node);
209 buf->on_dirty_list = false;
214 /**@brief Dynamic initialization of block cache.
215 * @param bc block cache descriptor
216 * @param cnt items count in block cache
217 * @param itemsize single item size (in bytes)
218 * @return standard error code*/
219 int ext4_bcache_init_dynamic(struct ext4_bcache *bc, uint32_t cnt,
222 /**@brief Do cleanup works on block cache.
223 * @param bc block cache descriptor.*/
224 void ext4_bcache_cleanup(struct ext4_bcache *bc);
226 /**@brief Dynamic de-initialization of block cache.
227 * @param bc block cache descriptor
228 * @return standard error code*/
229 int ext4_bcache_fini_dynamic(struct ext4_bcache *bc);
231 /**@brief Get a buffer with the lowest LRU counter in bcache.
232 * @param bc block cache descriptor
233 * @return buffer with the lowest LRU counter*/
234 struct ext4_buf *ext4_buf_lowest_lru(struct ext4_bcache *bc);
236 /**@brief Drop unreferenced buffer from bcache.
237 * @param bc block cache descriptor
238 * @param buf buffer*/
239 void ext4_bcache_drop_buf(struct ext4_bcache *bc, struct ext4_buf *buf);
241 /**@brief Allocate block from block cache memory.
242 * Unreferenced block allocation is based on LRU
243 * (Last Recently Used) algorithm.
244 * @param bc block cache descriptor
245 * @param b block to alloc
246 * @param is_new block is new (needs to be read)
247 * @return standard error code*/
248 int ext4_bcache_alloc(struct ext4_bcache *bc, struct ext4_block *b,
251 /**@brief Free block from cache memory (decrement reference counter).
252 * @param bc block cache descriptor
253 * @param b block to free
254 * @return standard error code*/
255 int ext4_bcache_free(struct ext4_bcache *bc, struct ext4_block *b);
257 /**@brief Return a full status of block cache.
258 * @param bc block cache descriptor
259 * @return full status*/
260 bool ext4_bcache_is_full(struct ext4_bcache *bc);
266 #endif /* EXT4_BCACHE_H_ */