From baf07d60f5c5d5d0f0c9e844cde75691f1ceb3d1 Mon Sep 17 00:00:00 2001 From: Alberto Garcia Date: Mon, 11 May 2015 15:54:54 +0300 Subject: qcow2: simplify qcow2_cache_put() and qcow2_cache_entry_mark_dirty() Since all tables are now stored together, it is possible to obtain the position of a particular table directly from its address, so the operation becomes O(1). Signed-off-by: Alberto Garcia Reviewed-by: Stefan Hajnoczi Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf --- block/qcow2-cache.c | 32 +++++++++++++++----------------- 1 file changed, 15 insertions(+), 17 deletions(-) (limited to 'block/qcow2-cache.c') diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c index f0dfb69cc1..6e78c8ffba 100644 --- a/block/qcow2-cache.c +++ b/block/qcow2-cache.c @@ -49,6 +49,16 @@ static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs, return (uint8_t *) c->table_array + (size_t) table * s->cluster_size; } +static inline int qcow2_cache_get_table_idx(BlockDriverState *bs, + Qcow2Cache *c, void *table) +{ + BDRVQcowState *s = bs->opaque; + ptrdiff_t table_offset = (uint8_t *) table - (uint8_t *) c->table_array; + int idx = table_offset / s->cluster_size; + assert(idx >= 0 && idx < c->size && table_offset % s->cluster_size == 0); + return idx; +} + Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables) { BDRVQcowState *s = bs->opaque; @@ -337,16 +347,12 @@ int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset, int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table) { - int i; + int i = qcow2_cache_get_table_idx(bs, c, *table); - for (i = 0; i < c->size; i++) { - if (qcow2_cache_get_table_addr(bs, c, i) == *table) { - goto found; - } + if (c->entries[i].offset == 0) { + return -ENOENT; } - return -ENOENT; -found: c->entries[i].ref--; *table = NULL; @@ -357,15 +363,7 @@ found: void qcow2_cache_entry_mark_dirty(BlockDriverState *bs, Qcow2Cache *c, void *table) { - int i; - - for (i = 0; i < c->size; i++) { - if (qcow2_cache_get_table_addr(bs, c, i) == table) { - goto found; - } - } - abort(); - -found: + int i = qcow2_cache_get_table_idx(bs, c, table); + assert(c->entries[i].offset != 0); c->entries[i].dirty = true; } -- cgit v1.2.1