f2fs: maintain extent cache in separated file

This patch moves extent cache related code from data.c into extent_cache.c
since extent cache is independent feature, and its codes are not relate to
others in data.c, it's better for us to maintain them in separated place.

There is no functionality change, but several small coding style fixes
including:
* rename __drop_largest_extent to f2fs_drop_largest_extent for exporting;
* rename misspelled word 'untill' to 'until';
* remove unneeded 'return' in the end of f2fs_destroy_extent_tree().
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/Makefile

@@ -2,7 +2,7 @@ obj-$(CONFIG_F2FS_FS) += f2fs.o
 
 f2fs-y		:= dir.o file.o inode.o namei.o hash.o super.o inline.o
 f2fs-y		+= checkpoint.o gc.o data.o node.o segment.o recovery.o
-f2fs-y		+= shrinker.o
+f2fs-y		+= shrinker.o extent_cache.o
 f2fs-$(CONFIG_F2FS_STAT_FS) += debug.o
 f2fs-$(CONFIG_F2FS_FS_XATTR) += xattr.o
 f2fs-$(CONFIG_F2FS_FS_POSIX_ACL) += acl.o

fs/f2fs/f2fs.h

@@ -1766,20 +1766,12 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *);
 void set_data_blkaddr(struct dnode_of_data *);
 int reserve_new_block(struct dnode_of_data *);
 int f2fs_reserve_block(struct dnode_of_data *, pgoff_t);
-unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
-void f2fs_init_extent_tree(struct inode *, struct f2fs_extent *);
-unsigned int f2fs_destroy_extent_node(struct inode *);
-void f2fs_destroy_extent_tree(struct inode *);
-void f2fs_update_extent_cache(struct dnode_of_data *);
 struct page *get_read_data_page(struct inode *, pgoff_t, int);
 struct page *find_data_page(struct inode *, pgoff_t);
 struct page *get_lock_data_page(struct inode *, pgoff_t);
 struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
 int do_write_data_page(struct f2fs_io_info *);
 int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *, u64, u64);
-void init_extent_cache_info(struct f2fs_sb_info *);
-int __init create_extent_cache(void);
-void destroy_extent_cache(void);
 void f2fs_invalidate_page(struct page *, unsigned int, unsigned int);
 int f2fs_release_page(struct page *, gfp_t);
 
@@ -1976,6 +1968,20 @@ unsigned long f2fs_shrink_scan(struct shrinker *, struct shrink_control *);
 void f2fs_join_shrinker(struct f2fs_sb_info *);
 void f2fs_leave_shrinker(struct f2fs_sb_info *);
 
+/*
+ * extent_cache.c
+ */
+unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
+void f2fs_drop_largest_extent(struct inode *, pgoff_t);
+void f2fs_init_extent_tree(struct inode *, struct f2fs_extent *);
+unsigned int f2fs_destroy_extent_node(struct inode *);
+void f2fs_destroy_extent_tree(struct inode *);
+bool f2fs_lookup_extent_cache(struct inode *, pgoff_t, struct extent_info *);
+void f2fs_update_extent_cache(struct dnode_of_data *);
+void init_extent_cache_info(struct f2fs_sb_info *);
+int __init create_extent_cache(void);
+void destroy_extent_cache(void);
+
 /*
  * crypto support
  */