btrfs: Remove redundant tree argument from extent_readpages

This function is called only from btrfs_readpage and is already passed
the mapping. Simplify its signature by moving the code obtaining
reference to the extent tree in the function. No functional changes.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -4126,9 +4126,8 @@ int extent_writepages(struct extent_io_tree *tree,
 	return ret;
 }
 
-int extent_readpages(struct extent_io_tree *tree,
-		     struct address_space *mapping,
-		     struct list_head *pages, unsigned nr_pages)
+int extent_readpages(struct address_space *mapping, struct list_head *pages,
+		     unsigned nr_pages)
 {
 	struct bio *bio = NULL;
 	unsigned page_idx;
@@ -4136,6 +4135,7 @@ int extent_readpages(struct extent_io_tree *tree,
 	struct page *pagepool[16];
 	struct page *page;
 	struct extent_map *em_cached = NULL;
+	struct extent_io_tree *tree = &BTRFS_I(mapping->host)->io_tree;
 	int nr = 0;
 	u64 prev_em_start = (u64)-1;
 

fs/btrfs/extent_io.h

@@ -416,9 +416,8 @@ int extent_writepages(struct extent_io_tree *tree,
 		      struct writeback_control *wbc);
 int btree_write_cache_pages(struct address_space *mapping,
 			    struct writeback_control *wbc);
-int extent_readpages(struct extent_io_tree *tree,
-		     struct address_space *mapping,
-		     struct list_head *pages, unsigned nr_pages);
+int extent_readpages(struct address_space *mapping, struct list_head *pages,
+		     unsigned nr_pages);
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		__u64 start, __u64 len);
 void set_page_extent_mapped(struct page *page);

fs/btrfs/inode.c

@@ -8907,10 +8907,9 @@ static int
 btrfs_readpages(struct file *file, struct address_space *mapping,
 		struct list_head *pages, unsigned nr_pages)
 {
-	struct extent_io_tree *tree;
-	tree = &BTRFS_I(mapping->host)->io_tree;
-	return extent_readpages(tree, mapping, pages, nr_pages);
+	return extent_readpages(mapping, pages, nr_pages);
 }
+
 static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
 {
 	int ret = try_release_extent_mapping(page, gfp_flags);