f2fs: test before set/clear bits

If the bit is already set, we don't need to reset it, and vice versa.
Because we don't need to make the caches dirty for that.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -1003,6 +1003,7 @@ enum {
 
 static inline void set_inode_flag(struct f2fs_inode_info *fi, int flag)
 {
+	if (!test_bit(flag, &fi->flags))
 		set_bit(flag, &fi->flags);
 }
 
@@ -1013,6 +1014,7 @@ static inline int is_inode_flag_set(struct f2fs_inode_info *fi, int flag)
 
 static inline void clear_inode_flag(struct f2fs_inode_info *fi, int flag)
 {
+	if (test_bit(flag, &fi->flags))
 		clear_bit(flag, &fi->flags);
 }