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>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 10eca02..dca18b3 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -574,7 +574,7 @@
 static inline int check_nid_range(struct f2fs_sb_info *sbi, nid_t nid)
 {
 	WARN_ON((nid >= NM_I(sbi)->max_nid));
-	if (nid >= NM_I(sbi)->max_nid)
+	if (unlikely(nid >= NM_I(sbi)->max_nid))
 		return -EINVAL;
 	return 0;
 }
@@ -600,7 +600,7 @@
 	spin_lock(&sbi->stat_lock);
 	valid_block_count =
 		sbi->total_valid_block_count + (block_t)count;
-	if (valid_block_count > sbi->user_block_count) {
+	if (unlikely(valid_block_count > sbi->user_block_count)) {
 		spin_unlock(&sbi->stat_lock);
 		return false;
 	}
@@ -719,13 +719,13 @@
 	spin_lock(&sbi->stat_lock);
 
 	valid_block_count = sbi->total_valid_block_count + 1;
-	if (valid_block_count > sbi->user_block_count) {
+	if (unlikely(valid_block_count > sbi->user_block_count)) {
 		spin_unlock(&sbi->stat_lock);
 		return false;
 	}
 
 	valid_node_count = sbi->total_valid_node_count + 1;
-	if (valid_node_count > sbi->total_node_count) {
+	if (unlikely(valid_node_count > sbi->total_node_count)) {
 		spin_unlock(&sbi->stat_lock);
 		return false;
 	}