[Ocfs2-devel] [PATCH] ocfs2: optimize ocfs2_check_dir_entry() with unlikely() annotations
Tao Ma
tm at tao.ma
Mon Jan 24 07:23:30 PST 2011
From: Tao Ma <boyu.mt at taobao.com>
In cad3f00, ext4_check_dir_entry was modified by adding some unlikely.
Ted described it as "This function gets called a lot for large
directories, and the answer is almost always 'no, no, there's no problem'.
This means using unlikely() is a good thing."
ext3 added the similar change in commit a4ae309.
So change it accordingly in ocfs2.
Cc: Joel Becker <jlbec at evilplan.org>
Signed-off-by: Tao Ma <boyu.mt at taobao.com>
---
fs/ocfs2/dir.c | 12 +++++++-----
1 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index d417b3f..41b356f 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -322,21 +322,23 @@ static int ocfs2_check_dir_entry(struct inode * dir,
const char *error_msg = NULL;
const int rlen = le16_to_cpu(de->rec_len);
- if (rlen < OCFS2_DIR_REC_LEN(1))
+ if (unlikely(rlen < OCFS2_DIR_REC_LEN(1)))
error_msg = "rec_len is smaller than minimal";
- else if (rlen % 4 != 0)
+ else if (unlikely(rlen % 4 != 0))
error_msg = "rec_len % 4 != 0";
- else if (rlen < OCFS2_DIR_REC_LEN(de->name_len))
+ else if (unlikely(rlen < OCFS2_DIR_REC_LEN(de->name_len)))
error_msg = "rec_len is too small for name_len";
- else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
+ else if (unlikely(
+ ((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize))
error_msg = "directory entry across blocks";
- if (error_msg != NULL)
+ if (unlikely(error_msg != NULL))
mlog(ML_ERROR, "bad entry in directory #%llu: %s - "
"offset=%lu, inode=%llu, rec_len=%d, name_len=%d\n",
(unsigned long long)OCFS2_I(dir)->ip_blkno, error_msg,
offset, (unsigned long long)le64_to_cpu(de->inode), rlen,
de->name_len);
+
return error_msg == NULL ? 1 : 0;
}
--
1.7.1
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