[PATCH] fs: Optimize unixbench's file copy test

[zenghongling]

The iomap_set_range_uptodate function checks if the file is a private
mapping,and if it is, it needs to do something about it.UnixBench's
file copy tests are mostly share mapping, such a check would reduce
file copy scores, so we added the unlikely macro for optimization.
and the score of file copy can be improved after branch optimization.
As follows:

./Run -c 8 -i 3 fstime fsbuffer fsdisk

Before the optimization
System Benchmarks Partial Index              BASELINE       RESULT    INDEX
File Copy 1024 bufsize 2000 maxblocks          3960.0     689276.0   1740.6
File Copy 256 bufsize 500 maxblocks            1655.0     204133.0   1233.4
File Copy 4096 bufsize 8000 maxblocks          5800.0    1526945.0   2632.7
                                                                   ========
System Benchmarks Index Score (Partial Only)                         1781.3

After the optimization
System Benchmarks Partial Index              BASELINE       RESULT    INDEX
File Copy 1024 bufsize 2000 maxblocks          3960.0     741524.0   1872.5
File Copy 256 bufsize 500 maxblocks            1655.0     208334.0   1258.8
File Copy 4096 bufsize 8000 maxblocks          5800.0    1641660.0   2830.4
                                                                   ========
System Benchmarks Index Score (Partial Only)                         1882.6

Signed-off-by: zenghongling <zenghongling@xxxxxxxxxx>
---
 fs/iomap/buffered-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 53cd7b2..35a50c2 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -148,7 +148,7 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
 	if (PageError(page))
 		return;
 
-	if (page_has_private(page))
+	if (unlikely(page_has_private(page)))
 		iomap_iop_set_range_uptodate(page, off, len);
 	else
 		SetPageUptodate(page);
-- 
2.1.0