All callers pass btree_get_extent, which needs to be exported.
Signed-off-by: David Sterba <dsterba@suse.com>
  * extents on the btree inode are pretty simple, there's one extent
  * that covers the entire device
  */
-static struct extent_map *btree_get_extent(struct btrfs_inode *inode,
+struct extent_map *btree_get_extent(struct btrfs_inode *inode,
                struct page *page, size_t pg_offset, u64 start, u64 len,
                int create)
 {
        io_tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
        while (1) {
                ret = read_extent_buffer_pages(io_tree, eb, WAIT_COMPLETE,
-                                              btree_get_extent, mirror_num);
+                                              mirror_num);
                if (!ret) {
                        if (!verify_parent_transid(io_tree, eb,
                                                   parent_transid, 0))
        if (IS_ERR(buf))
                return;
        read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
-                                buf, WAIT_NONE, btree_get_extent, 0);
+                                buf, WAIT_NONE, 0);
        free_extent_buffer(buf);
 }
 
        set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags);
 
        ret = read_extent_buffer_pages(io_tree, buf, WAIT_PAGE_LOCK,
-                                      btree_get_extent, mirror_num);
+                                      mirror_num);
        if (ret) {
                free_extent_buffer(buf);
                return ret;
 
                                     u64 objectid);
 int btree_lock_page_hook(struct page *page, void *data,
                                void (*flush_fn)(void *));
+struct extent_map *btree_get_extent(struct btrfs_inode *inode,
+               struct page *page, size_t pg_offset, u64 start, u64 len,
+               int create);
 int btrfs_get_num_tolerated_disk_barrier_failures(u64 flags);
 int __init btrfs_end_io_wq_init(void);
 void btrfs_end_io_wq_exit(void);
 
 #include "locking.h"
 #include "rcu-string.h"
 #include "backref.h"
+#include "disk-io.h"
 
 static struct kmem_cache *extent_state_cache;
 static struct kmem_cache *extent_buffer_cache;
 }
 
 int read_extent_buffer_pages(struct extent_io_tree *tree,
-                            struct extent_buffer *eb, int wait,
-                            get_extent_t *get_extent, int mirror_num)
+                            struct extent_buffer *eb, int wait, int mirror_num)
 {
        unsigned long i;
        struct page *page;
 
                        ClearPageError(page);
                        err = __extent_read_full_page(tree, page,
-                                                     get_extent, &bio,
+                                                     btree_get_extent, &bio,
                                                      mirror_num, &bio_flags,
                                                      REQ_META);
                        if (err) {
 
 #define WAIT_PAGE_LOCK 2
 int read_extent_buffer_pages(struct extent_io_tree *tree,
                             struct extent_buffer *eb, int wait,
-                            get_extent_t *get_extent, int mirror_num);
+                            int mirror_num);
 void wait_on_extent_buffer_writeback(struct extent_buffer *eb);
 
 static inline unsigned long num_extent_pages(u64 start, u64 len)