nilfs2: optimize rec_len functions

This is a similar change to those in ext2/ext3 codebase (commit
40a063f6691ce937 and a4ae3094869f18e2, 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>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index fdcd1bc7f61f..3a65e5aa2d76 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -326,17 +326,21 @@ static inline unsigned nilfs_rec_len_from_disk(__le16 dlen)
 {
         unsigned len = le16_to_cpu(dlen);
 
+#if !defined(__KERNEL__) || (PAGE_CACHE_SIZE >= 65536)
         if (len == NILFS_MAX_REC_LEN)
                 return 1 << 16;
+#endif
         return len;
 }
 
 static inline __le16 nilfs_rec_len_to_disk(unsigned len)
 {
+#if !defined(__KERNEL__) || (PAGE_CACHE_SIZE >= 65536)
         if (len == (1 << 16))
                 return cpu_to_le16(NILFS_MAX_REC_LEN);
         else if (len > (1 << 16))
                 BUG();
+#endif
         return cpu_to_le16(len);
 }