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authorRobin Dong <hao.bigrat@gmail.com>2011-07-17 23:27:43 -0400
committerTheodore Ts'o <tytso@mit.edu>2011-07-17 23:27:43 -0400
commit015861badd0db43d025bbb538f8fc62dfaf3f18d (patch)
treee1e7f6ea3f4cd41ecc030f07a4a454141dd2e158 /fs/ext4
parentc6a0371cbefade85376bbc326d18451860632dce (diff)
downloadblackbird-op-linux-015861badd0db43d025bbb538f8fc62dfaf3f18d.tar.gz
blackbird-op-linux-015861badd0db43d025bbb538f8fc62dfaf3f18d.zip
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 <sanbai@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Eric Gouriou <egouriou@google.com>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/extents.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 3d8c5f50ba33..b8acfab00224 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) {
/*
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