Btrfs: remove unused extent io tree ops V2

Nobody uses these io tree ops anymore so just remove them and clean up the code
a bit.  Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/extent_io.c

@@ -2646,6 +2646,8 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
 		}
 	}
 	while (cur <= end) {
+		unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
+
 		if (cur >= last_byte) {
 			char *userpage;
 			struct extent_state *cached = NULL;
@@ -2733,13 +2735,6 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
 			continue;
 		}
 
-		ret = 0;
-		if (tree->ops && tree->ops->readpage_io_hook) {
-			ret = tree->ops->readpage_io_hook(page, cur,
-							  cur + iosize - 1);
-		}
-		if (!ret) {
-			unsigned long pnr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
 		pnr -= page->index;
 		ret = submit_extent_page(READ, tree, page,
 					 sector, disk_io_size, pg_offset,
@@ -2750,9 +2745,7 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
 		if (!ret) {
 			nr++;
 			*bio_flags = this_bio_flag;
-			}
-		}
-		if (ret) {
+		} else {
 			SetPageError(page);
 			unlock_extent(tree, cur, cur + iosize - 1);
 		}
@@ -3441,16 +3434,10 @@ static int extent_write_cache_pages(struct extent_io_tree *tree,
 			 * swizzled back from swapper_space to tmpfs file
 			 * mapping
 			 */
-			if (tree->ops &&
-			    tree->ops->write_cache_pages_lock_hook) {
-				tree->ops->write_cache_pages_lock_hook(page,
-							       data, flush_fn);
-			} else {
 			if (!trylock_page(page)) {
 				flush_fn(data);
 				lock_page(page);
 			}
-			}
 
 			if (unlikely(page->mapping != mapping)) {
 				unlock_page(page);

fs/btrfs/extent_io.h

@@ -75,7 +75,6 @@ struct extent_io_ops {
 	int (*merge_bio_hook)(struct page *page, unsigned long offset,
 			      size_t size, struct bio *bio,
 			      unsigned long bio_flags);
-	int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
 	int (*readpage_io_failed_hook)(struct page *page, int failed_mirror);
 	int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end,
 				    struct extent_state *state, int mirror);
@@ -90,8 +89,6 @@ struct extent_io_ops {
 				  struct extent_state *other);
 	void (*split_extent_hook)(struct inode *inode,
 				  struct extent_state *orig, u64 split);
-	int (*write_cache_pages_lock_hook)(struct page *page, void *data,
-					   void (*flush_fn)(void *));
 };
 
 struct extent_io_tree {