f2fs: move ext_lock out of struct extent_info

Move ext_lock out of struct extent_info, then in the following patches we can
use variables with struct extent_info type as a parameter to pass pure data.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index f8da399..c3caa3c 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -277,7 +277,6 @@
 #define F2FS_MIN_EXTENT_LEN	16	/* minimum extent length */
 
 struct extent_info {
-	rwlock_t ext_lock;	/* rwlock for consistency */
 	unsigned int fofs;	/* start offset in a file */
 	u32 blk_addr;		/* start block address of the extent */
 	unsigned int len;	/* length of the extent */
@@ -309,6 +308,7 @@
 	nid_t i_xattr_nid;		/* node id that contains xattrs */
 	unsigned long long xattr_ver;	/* cp version of xattr modification */
 	struct extent_info ext;		/* in-memory extent cache entry */
+	rwlock_t ext_lock;		/* rwlock for single extent cache */
 	struct inode_entry *dirty_dir;	/* the pointer of dirty dir */
 
 	struct radix_tree_root inmem_root;	/* radix tree for inmem pages */
@@ -319,21 +319,17 @@
 static inline void get_extent_info(struct extent_info *ext,
 					struct f2fs_extent i_ext)
 {
-	write_lock(&ext->ext_lock);
 	ext->fofs = le32_to_cpu(i_ext.fofs);
 	ext->blk_addr = le32_to_cpu(i_ext.blk_addr);
 	ext->len = le32_to_cpu(i_ext.len);
-	write_unlock(&ext->ext_lock);
 }
 
 static inline void set_raw_extent(struct extent_info *ext,
 					struct f2fs_extent *i_ext)
 {
-	read_lock(&ext->ext_lock);
 	i_ext->fofs = cpu_to_le32(ext->fofs);
 	i_ext->blk_addr = cpu_to_le32(ext->blk_addr);
 	i_ext->len = cpu_to_le32(ext->len);
-	read_unlock(&ext->ext_lock);
 }
 
 struct f2fs_nm_info {