[PATCH] Trivial optimization of ll_rw_block()

The ll_rw_block() needs to get ref-count only if it submits a buffer().  This
patch avoids the needless get/put of ref-count.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/buffer.c b/fs/buffer.c
index 5e4a90e..62cfd17 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2867,22 +2867,22 @@ void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
                else if (test_set_buffer_locked(bh))
                        continue;
 
-               get_bh(bh);
                if (rw == WRITE || rw == SWRITE) {
                        if (test_clear_buffer_dirty(bh)) {
                                bh->b_end_io = end_buffer_write_sync;
+                               get_bh(bh);
                                submit_bh(WRITE, bh);
                                continue;
                        }
                } else {
                        if (!buffer_uptodate(bh)) {
                                bh->b_end_io = end_buffer_read_sync;
+                               get_bh(bh);
                                submit_bh(rw, bh);
                                continue;
                        }
                }
                unlock_buffer(bh);
-               put_bh(bh);
        }
 }