f2fs: add unlikely() macro for compiler optimization

As we know, some of our branch condition will rarely be true. So we could add
'unlikely' to let compiler optimize these code, by this way we could drop
unneeded 'jump' assemble code to improve performance.

change log:
 o add *unlikely* as many as possible across the whole source files at once
   suggested by Jaegeuk Kim.

Suggested-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

1 files changed, 16 insertions, 10 deletions

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 38f4a2245085..6b2106685b7a 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -82,13 +82,12 @@ static int f2fs_write_meta_page(struct page *page,
 	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 
 	/* Should not write any meta pages, if any IO error was occurred */
-	if (wbc->for_reclaim || sbi->por_doing ||
-			is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ERROR_FLAG)) {
-		dec_page_count(sbi, F2FS_DIRTY_META);
-		wbc->pages_skipped++;
-		set_page_dirty(page);
-		return AOP_WRITEPAGE_ACTIVATE;
-	}
+	if (unlikely(sbi->por_doing ||
+			is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ERROR_FLAG)))
+		goto redirty_out;
+
+	if (wbc->for_reclaim)
+		goto redirty_out;
 
 	wait_on_page_writeback(page);
 
@@ -96,6 +95,12 @@ static int f2fs_write_meta_page(struct page *page,
 	dec_page_count(sbi, F2FS_DIRTY_META);
 	unlock_page(page);
 	return 0;
+
+redirty_out:
+	dec_page_count(sbi, F2FS_DIRTY_META);
+	wbc->pages_skipped++;
+	set_page_dirty(page);
+	return AOP_WRITEPAGE_ACTIVATE;
 }
 
 static int f2fs_write_meta_pages(struct address_space *mapping,
@@ -137,7 +142,7 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
 		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 				PAGECACHE_TAG_DIRTY,
 				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
-		if (nr_pages == 0)
+		if (unlikely(nr_pages == 0))
 			break;
 
 		for (i = 0; i < nr_pages; i++) {
@@ -150,7 +155,8 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
 				unlock_page(page);
 				break;
 			}
-			if (nwritten++ >= nr_to_write)
+			nwritten++;
+			if (unlikely(nwritten >= nr_to_write))
 				break;
 		}
 		pagevec_release(&pvec);
@@ -200,7 +206,7 @@ int acquire_orphan_inode(struct f2fs_sb_info *sbi)
 	max_orphans = (sbi->blocks_per_seg - 2 - NR_CURSEG_TYPE)
 				* F2FS_ORPHANS_PER_BLOCK;
 	mutex_lock(&sbi->orphan_inode_mutex);
-	if (sbi->n_orphans >= max_orphans)
+	if (unlikely(sbi->n_orphans >= max_orphans))
 		err = -ENOSPC;
 	else
 		sbi->n_orphans++;