diff options
Diffstat (limited to 'drivers/block/blkcache.c')
-rw-r--r-- | drivers/block/blkcache.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/drivers/block/blkcache.c b/drivers/block/blkcache.c new file mode 100644 index 0000000..46a6059 --- /dev/null +++ b/drivers/block/blkcache.c @@ -0,0 +1,173 @@ +/* + * Copyright (C) Nelson Integration, LLC 2016 + * Author: Eric Nelson<eric@nelint.com> + * + * SPDX-License-Identifier: GPL-2.0+ + * + */ +#include <config.h> +#include <common.h> +#include <malloc.h> +#include <part.h> +#include <linux/ctype.h> +#include <linux/list.h> + +struct block_cache_node { + struct list_head lh; + int iftype; + int devnum; + lbaint_t start; + lbaint_t blkcnt; + unsigned long blksz; + char *cache; +}; + +static LIST_HEAD(block_cache); + +static struct block_cache_stats _stats = { + .max_blocks_per_entry = 2, + .max_entries = 32 +}; + +static struct block_cache_node *cache_find(int iftype, int devnum, + lbaint_t start, lbaint_t blkcnt, + unsigned long blksz) +{ + struct block_cache_node *node; + + list_for_each_entry(node, &block_cache, lh) + if ((node->iftype == iftype) && + (node->devnum == devnum) && + (node->blksz == blksz) && + (node->start <= start) && + (node->start + node->blkcnt >= start + blkcnt)) { + if (block_cache.next != &node->lh) { + /* maintain MRU ordering */ + list_del(&node->lh); + list_add(&node->lh, &block_cache); + } + return node; + } + return 0; +} + +int blkcache_read(int iftype, int devnum, + lbaint_t start, lbaint_t blkcnt, + unsigned long blksz, void *buffer) +{ + struct block_cache_node *node = cache_find(iftype, devnum, start, + blkcnt, blksz); + if (node) { + const char *src = node->cache + (start - node->start) * blksz; + memcpy(buffer, src, blksz * blkcnt); + debug("hit: start " LBAF ", count " LBAFU "\n", + start, blkcnt); + ++_stats.hits; + return 1; + } + + debug("miss: start " LBAF ", count " LBAFU "\n", + start, blkcnt); + ++_stats.misses; + return 0; +} + +void blkcache_fill(int iftype, int devnum, + lbaint_t start, lbaint_t blkcnt, + unsigned long blksz, void const *buffer) +{ + lbaint_t bytes; + struct block_cache_node *node; + + /* don't cache big stuff */ + if (blkcnt > _stats.max_blocks_per_entry) + return; + + if (_stats.max_entries == 0) + return; + + bytes = blksz * blkcnt; + if (_stats.max_entries <= _stats.entries) { + /* pop LRU */ + node = (struct block_cache_node *)block_cache.prev; + list_del(&node->lh); + _stats.entries--; + debug("drop: start " LBAF ", count " LBAFU "\n", + node->start, node->blkcnt); + if (node->blkcnt * node->blksz < bytes) { + free(node->cache); + node->cache = 0; + } + } else { + node = malloc(sizeof(*node)); + if (!node) + return; + node->cache = 0; + } + + if (!node->cache) { + node->cache = malloc(bytes); + if (!node->cache) { + free(node); + return; + } + } + + debug("fill: start " LBAF ", count " LBAFU "\n", + start, blkcnt); + + node->iftype = iftype; + node->devnum = devnum; + node->start = start; + node->blkcnt = blkcnt; + node->blksz = blksz; + memcpy(node->cache, buffer, bytes); + list_add(&node->lh, &block_cache); + _stats.entries++; +} + +void blkcache_invalidate(int iftype, int devnum) +{ + struct list_head *entry, *n; + struct block_cache_node *node; + + list_for_each_safe(entry, n, &block_cache) { + node = (struct block_cache_node *)entry; + if ((node->iftype == iftype) && + (node->devnum == devnum)) { + list_del(entry); + free(node->cache); + free(node); + --_stats.entries; + } + } +} + +void blkcache_configure(unsigned blocks, unsigned entries) +{ + struct block_cache_node *node; + if ((blocks != _stats.max_blocks_per_entry) || + (entries != _stats.max_entries)) { + /* invalidate cache */ + while (!list_empty(&block_cache)) { + node = (struct block_cache_node *)block_cache.next; + list_del(&node->lh); + free(node->cache); + free(node); + } + _stats.entries = 0; + } + + _stats.max_blocks_per_entry = blocks; + _stats.max_entries = entries; + + _stats.hits = 0; + _stats.misses = 0; +} + +void blkcache_stats(struct block_cache_stats *stats) +{ + memcpy(stats, &_stats, sizeof(*stats)); + _stats.hits = 0; + _stats.misses = 0; +} |