From: Robin Dong Date: Mon, 18 Jul 2011 03:27:43 +0000 (-0400) Subject: ext4: avoid wasted extent cache lookup if !PUNCH_OUT_EXT X-Git-Tag: v3.1-rc1~90^2~30 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=015861badd0db43d025bbb538f8fc62dfaf3f18d;p=platform%2Fkernel%2Flinux-3.10.git ext4: avoid wasted extent cache lookup if !PUNCH_OUT_EXT This patch avoids an extraneous lookup of the extent cache in ext4_ext_map_blocks() when the flag EXT4_GET_BLOCKS_PUNCH_OUT_EXT is absent. The existing logic was performing the lookup but not making use of the result. The patch simply reverses the order of evaluation in the condition. Since ext4_ext_in_cache() does not initialize newex on misses, bypassing its invocation does not introduce any new issue in this regard. Signed-off-by: Robin Dong Signed-off-by: "Theodore Ts'o" Reviewed-by: Lukas Czerner Reviewed-by: Eric Gouriou --- diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 3d8c5f50..b8acfab 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3320,8 +3320,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags); /* check in cache */ - if (ext4_ext_in_cache(inode, map->m_lblk, &newex) && - ((flags & EXT4_GET_BLOCKS_PUNCH_OUT_EXT) == 0)) { + if (!(flags & EXT4_GET_BLOCKS_PUNCH_OUT_EXT) && + ext4_ext_in_cache(inode, map->m_lblk, &newex)) { if (!newex.ee_start_lo && !newex.ee_start_hi) { if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) { /*