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 #include "ext4_config.h"
38 #include "ext4_bcache.h"
39 #include "ext4_blockdev.h"
40 #include "ext4_debug.h"
41 #include "ext4_errno.h"
46 static int ext4_bcache_lba_compare(struct ext4_buf *a, struct ext4_buf *b)
50 else if (a->lba < b->lba)
55 static int ext4_bcache_lru_compare(struct ext4_buf *a, struct ext4_buf *b)
57 if (a->lru_id > b->lru_id)
59 else if (a->lru_id < b->lru_id)
64 RB_GENERATE_INTERNAL(ext4_buf_lba, ext4_buf, lba_node,
65 ext4_bcache_lba_compare, static inline)
66 RB_GENERATE_INTERNAL(ext4_buf_lru, ext4_buf, lru_node,
67 ext4_bcache_lru_compare, static inline)
69 int ext4_bcache_init_dynamic(struct ext4_bcache *bc, uint32_t cnt,
72 ext4_assert(bc && cnt && itemsize);
74 memset(bc, 0, sizeof(struct ext4_bcache));
77 bc->itemsize = itemsize;
79 bc->max_ref_blocks = 0;
84 int ext4_bcache_fini_dynamic(struct ext4_bcache *bc)
86 memset(bc, 0, sizeof(struct ext4_bcache));
92 * This is ext4_bcache, the module handling basic buffer-cache stuff.
94 * Buffers in a bcache are sorted by their LBA and stored in a
97 * Bcache also maintains another RB-Tree(lru_root) right now, where
98 * buffers are sorted by their LRU id.
100 * A singly-linked list is used to track those dirty buffers which are
101 * ready to be flushed. (Those buffers which are dirty but also referenced
102 * are not considered ready to be flushed.)
104 * When a buffer is not referenced, it will be stored in both lba_root
105 * and lru_root, while it will only be stored in lba_root when it is
109 static struct ext4_buf *
110 ext4_buf_alloc(struct ext4_bcache *bc, uint64_t lba)
113 struct ext4_buf *buf;
114 data = malloc(bc->itemsize);
118 buf = calloc(1, sizeof(struct ext4_buf));
129 static void ext4_buf_free(struct ext4_buf *buf)
135 static struct ext4_buf *
136 ext4_buf_lookup(struct ext4_bcache *bc, uint64_t lba)
138 struct ext4_buf tmp = {
142 return RB_FIND(ext4_buf_lba, &bc->lba_root, &tmp);
145 struct ext4_buf *ext4_buf_lowest_lru(struct ext4_bcache *bc)
147 return RB_MIN(ext4_buf_lru, &bc->lru_root);
150 void ext4_bcache_drop_buf(struct ext4_bcache *bc, struct ext4_buf *buf)
152 /*Cannot drop any referenced buffers.*/
153 ext4_assert(!buf->refctr);
155 RB_REMOVE(ext4_buf_lba, &bc->lba_root, buf);
156 RB_REMOVE(ext4_buf_lru, &bc->lru_root, buf);
158 /*Forcibly drop dirty buffer.*/
159 if (ext4_bcache_test_flag(buf, BC_DIRTY))
160 ext4_bcache_remove_dirty_node(bc, buf);
166 int ext4_bcache_alloc(struct ext4_bcache *bc, struct ext4_block *b,
169 /* Try to search the buffer with exaxt LBA. */
170 struct ext4_buf *buf = ext4_buf_lookup(bc, b->lb_id);
172 /* If buffer is not referenced. */
174 /* Assign new value to LRU id and increment LRU counter
176 buf->lru_id = ++bc->lru_ctr;
177 RB_REMOVE(ext4_buf_lru, &bc->lru_root, buf);
178 if (ext4_bcache_test_flag(buf, BC_DIRTY))
179 ext4_bcache_remove_dirty_node(bc, buf);
183 ext4_bcache_inc_ref(buf);
192 /* We need to allocate one buffer.*/
193 buf = ext4_buf_alloc(bc, b->lb_id);
197 RB_INSERT(ext4_buf_lba, &bc->lba_root, buf);
198 /* One more buffer in bcache now. :-) */
201 ext4_bcache_inc_ref(buf);
202 /* Assign new value to LRU id and increment LRU counter
204 buf->lru_id = ++bc->lru_ctr;
213 int ext4_bcache_free(struct ext4_bcache *bc, struct ext4_block *b)
215 struct ext4_buf *buf = b->buf;
217 ext4_assert(bc && b);
220 ext4_assert(b->lb_id);
222 /*Block should have a valid pointer to ext4_buf.*/
225 /*Check if someone don't try free unreferenced block cache.*/
226 ext4_assert(buf->refctr);
228 /*Just decrease reference counter*/
229 ext4_bcache_dec_ref(buf);
231 /* We are the last one touching this buffer, do the cleanups. */
233 RB_INSERT(ext4_buf_lru, &bc->lru_root, buf);
234 /* This buffer is ready to be flushed. */
235 if (ext4_bcache_test_flag(buf, BC_DIRTY)) {
236 if (bc->bdev->cache_write_back)
237 ext4_bcache_insert_dirty_node(bc, buf);
239 ext4_block_flush_buf(bc->bdev, buf);
242 /* The buffer is invalidated...drop it. */
243 if (!ext4_bcache_test_flag(buf, BC_UPTODATE))
244 ext4_bcache_drop_buf(bc, buf);
254 bool ext4_bcache_is_full(struct ext4_bcache *bc)
256 return (bc->cnt <= bc->ref_blocks);