1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright (C) Nelson Integration, LLC 2016 4 * Author: Eric Nelson<eric@nelint.com> 5 * 6 */ 7 #include <config.h> 8 #include <common.h> 9 #include <malloc.h> 10 #include <part.h> 11 #include <linux/ctype.h> 12 #include <linux/list.h> 13 14 struct block_cache_node { 15 struct list_head lh; 16 int iftype; 17 int devnum; 18 lbaint_t start; 19 lbaint_t blkcnt; 20 unsigned long blksz; 21 char *cache; 22 }; 23 24 static LIST_HEAD(block_cache); 25 26 static struct block_cache_stats _stats = { 27 .max_blocks_per_entry = 2, 28 .max_entries = 32 29 }; 30 31 static struct block_cache_node *cache_find(int iftype, int devnum, 32 lbaint_t start, lbaint_t blkcnt, 33 unsigned long blksz) 34 { 35 struct block_cache_node *node; 36 37 list_for_each_entry(node, &block_cache, lh) 38 if ((node->iftype == iftype) && 39 (node->devnum == devnum) && 40 (node->blksz == blksz) && 41 (node->start <= start) && 42 (node->start + node->blkcnt >= start + blkcnt)) { 43 if (block_cache.next != &node->lh) { 44 /* maintain MRU ordering */ 45 list_del(&node->lh); 46 list_add(&node->lh, &block_cache); 47 } 48 return node; 49 } 50 return 0; 51 } 52 53 int blkcache_read(int iftype, int devnum, 54 lbaint_t start, lbaint_t blkcnt, 55 unsigned long blksz, void *buffer) 56 { 57 struct block_cache_node *node = cache_find(iftype, devnum, start, 58 blkcnt, blksz); 59 if (node) { 60 const char *src = node->cache + (start - node->start) * blksz; 61 memcpy(buffer, src, blksz * blkcnt); 62 debug("hit: start " LBAF ", count " LBAFU "\n", 63 start, blkcnt); 64 ++_stats.hits; 65 return 1; 66 } 67 68 debug("miss: start " LBAF ", count " LBAFU "\n", 69 start, blkcnt); 70 ++_stats.misses; 71 return 0; 72 } 73 74 void blkcache_fill(int iftype, int devnum, 75 lbaint_t start, lbaint_t blkcnt, 76 unsigned long blksz, void const *buffer) 77 { 78 lbaint_t bytes; 79 struct block_cache_node *node; 80 81 /* don't cache big stuff */ 82 if (blkcnt > _stats.max_blocks_per_entry) 83 return; 84 85 if (_stats.max_entries == 0) 86 return; 87 88 bytes = blksz * blkcnt; 89 if (_stats.max_entries <= _stats.entries) { 90 /* pop LRU */ 91 node = (struct block_cache_node *)block_cache.prev; 92 list_del(&node->lh); 93 _stats.entries--; 94 debug("drop: start " LBAF ", count " LBAFU "\n", 95 node->start, node->blkcnt); 96 if (node->blkcnt * node->blksz < bytes) { 97 free(node->cache); 98 node->cache = 0; 99 } 100 } else { 101 node = malloc(sizeof(*node)); 102 if (!node) 103 return; 104 node->cache = 0; 105 } 106 107 if (!node->cache) { 108 node->cache = malloc(bytes); 109 if (!node->cache) { 110 free(node); 111 return; 112 } 113 } 114 115 debug("fill: start " LBAF ", count " LBAFU "\n", 116 start, blkcnt); 117 118 node->iftype = iftype; 119 node->devnum = devnum; 120 node->start = start; 121 node->blkcnt = blkcnt; 122 node->blksz = blksz; 123 memcpy(node->cache, buffer, bytes); 124 list_add(&node->lh, &block_cache); 125 _stats.entries++; 126 } 127 128 void blkcache_invalidate(int iftype, int devnum) 129 { 130 struct list_head *entry, *n; 131 struct block_cache_node *node; 132 133 list_for_each_safe(entry, n, &block_cache) { 134 node = (struct block_cache_node *)entry; 135 if ((node->iftype == iftype) && 136 (node->devnum == devnum)) { 137 list_del(entry); 138 free(node->cache); 139 free(node); 140 --_stats.entries; 141 } 142 } 143 } 144 145 void blkcache_configure(unsigned blocks, unsigned entries) 146 { 147 struct block_cache_node *node; 148 if ((blocks != _stats.max_blocks_per_entry) || 149 (entries != _stats.max_entries)) { 150 /* invalidate cache */ 151 while (!list_empty(&block_cache)) { 152 node = (struct block_cache_node *)block_cache.next; 153 list_del(&node->lh); 154 free(node->cache); 155 free(node); 156 } 157 _stats.entries = 0; 158 } 159 160 _stats.max_blocks_per_entry = blocks; 161 _stats.max_entries = entries; 162 163 _stats.hits = 0; 164 _stats.misses = 0; 165 } 166 167 void blkcache_stats(struct block_cache_stats *stats) 168 { 169 memcpy(stats, &_stats, sizeof(*stats)); 170 _stats.hits = 0; 171 _stats.misses = 0; 172 } 173