From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42632) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yvoqh-0004V1-6s for qemu-devel@nongnu.org; Fri, 22 May 2015 11:27:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yvoqf-0006ZC-Kl for qemu-devel@nongnu.org; Fri, 22 May 2015 11:26:59 -0400 From: Kevin Wolf Date: Fri, 22 May 2015 17:26:24 +0200 Message-Id: <1432308400-13958-7-git-send-email-kwolf@redhat.com> In-Reply-To: <1432308400-13958-1-git-send-email-kwolf@redhat.com> References: <1432308400-13958-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 06/22] qcow2: simplify qcow2_cache_put() and qcow2_cache_entry_mark_dirty() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: Alberto Garcia 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(-) diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c index f0dfb69..6e78c8f 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; } -- 1.8.3.1