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nilfs2: optimize rec_len functions

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This is a similar change to those in ext2/ext3 codebase (commit
40a063f669 and a4ae309486, respectively).

The addition of 64k block capability in the rec_len_from_disk and
rec_len_to_disk functions added a bit of math overhead which slows
down file create workloads needlessly when the architecture cannot
even support 64k blocks.  This will cut the corner.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi 2011-02-04 01:19:38 +09:00
parent 4138ec2382
commit ae191838b0
2 changed files with 5 additions and 0 deletions
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1
fs/nilfs2/ioctl.c
View File

@ -28,6 +28,7 @@
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/compat.h> /* compat_ptr() */ #include <linux/compat.h> /* compat_ptr() */
#include <linux/mount.h> /* mnt_want_write(), mnt_drop_write() */ #include <linux/mount.h> /* mnt_want_write(), mnt_drop_write() */
#include <linux/buffer_head.h>
#include <linux/nilfs2_fs.h> #include <linux/nilfs2_fs.h>
#include "nilfs.h" #include "nilfs.h"
#include "segment.h" #include "segment.h"

4
include/linux/nilfs2_fs.h
View File

@ -326,17 +326,21 @@ static inline unsigned nilfs_rec_len_from_disk(__le16 dlen)
{ {
unsigned len = le16_to_cpu(dlen); unsigned len = le16_to_cpu(dlen);
#if !defined(__KERNEL__) || (PAGE_CACHE_SIZE >= 65536)
if (len == NILFS_MAX_REC_LEN) if (len == NILFS_MAX_REC_LEN)
return 1 << 16; return 1 << 16;
#endif
return len; return len;
} }
static inline __le16 nilfs_rec_len_to_disk(unsigned len) static inline __le16 nilfs_rec_len_to_disk(unsigned len)
{ {
#if !defined(__KERNEL__) || (PAGE_CACHE_SIZE >= 65536)
if (len == (1 << 16)) if (len == (1 << 16))
return cpu_to_le16(NILFS_MAX_REC_LEN); return cpu_to_le16(NILFS_MAX_REC_LEN);
else if (len > (1 << 16)) else if (len > (1 << 16))
BUG(); BUG();
#endif
return cpu_to_le16(len); return cpu_to_le16(len);
} }