2 * Copyright (C) Nelson Integration, LLC 2016
3 * Author: Eric Nelson<eric@nelint.com>
5 * SPDX-License-Identifier: GPL-2.0+
12 #include <linux/ctype.h>
13 #include <linux/list.h>
15 struct block_cache_node {
25 static LIST_HEAD(block_cache);
27 static struct block_cache_stats _stats = {
28 .max_blocks_per_entry = 2,
32 static struct block_cache_node *cache_find(int iftype, int devnum,
33 lbaint_t start, lbaint_t blkcnt,
36 struct block_cache_node *node;
38 list_for_each_entry(node, &block_cache, lh)
39 if ((node->iftype == iftype) &&
40 (node->devnum == devnum) &&
41 (node->blksz == blksz) &&
42 (node->start <= start) &&
43 (node->start + node->blkcnt >= start + blkcnt)) {
44 if (block_cache.next != &node->lh) {
45 /* maintain MRU ordering */
47 list_add(&node->lh, &block_cache);
54 int blkcache_read(int iftype, int devnum,
55 lbaint_t start, lbaint_t blkcnt,
56 unsigned long blksz, void *buffer)
58 struct block_cache_node *node = cache_find(iftype, devnum, start,
61 const char *src = node->cache + (start - node->start) * blksz;
62 memcpy(buffer, src, blksz * blkcnt);
63 debug("hit: start " LBAF ", count " LBAFU "\n",
69 debug("miss: start " LBAF ", count " LBAFU "\n",
75 void blkcache_fill(int iftype, int devnum,
76 lbaint_t start, lbaint_t blkcnt,
77 unsigned long blksz, void const *buffer)
80 struct block_cache_node *node;
82 /* don't cache big stuff */
83 if (blkcnt > _stats.max_blocks_per_entry)
86 if (_stats.max_entries == 0)
89 bytes = blksz * blkcnt;
90 if (_stats.max_entries <= _stats.entries) {
92 node = (struct block_cache_node *)block_cache.prev;
95 debug("drop: start " LBAF ", count " LBAFU "\n",
96 node->start, node->blkcnt);
97 if (node->blkcnt * node->blksz < bytes) {
102 node = malloc(sizeof(*node));
109 node->cache = malloc(bytes);
116 debug("fill: start " LBAF ", count " LBAFU "\n",
119 node->iftype = iftype;
120 node->devnum = devnum;
122 node->blkcnt = blkcnt;
124 memcpy(node->cache, buffer, bytes);
125 list_add(&node->lh, &block_cache);
129 void blkcache_invalidate(int iftype, int devnum)
131 struct list_head *entry, *n;
132 struct block_cache_node *node;
134 list_for_each_safe(entry, n, &block_cache) {
135 node = (struct block_cache_node *)entry;
136 if ((node->iftype == iftype) &&
137 (node->devnum == devnum)) {
146 void blkcache_configure(unsigned blocks, unsigned entries)
148 struct block_cache_node *node;
149 if ((blocks != _stats.max_blocks_per_entry) ||
150 (entries != _stats.max_entries)) {
151 /* invalidate cache */
152 while (!list_empty(&block_cache)) {
153 node = (struct block_cache_node *)block_cache.next;
161 _stats.max_blocks_per_entry = blocks;
162 _stats.max_entries = entries;
168 void blkcache_stats(struct block_cache_stats *stats)
170 memcpy(stats, &_stats, sizeof(*stats));