btrfs: Remove tree argument from extent_writepages

It can be directly referenced from the passed address_space so do that.
No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 20bb056..af2f040 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4109,14 +4109,13 @@ int extent_write_locked_range(struct inode *inode, u64 start, u64 end,
 	return ret;
 }
 
-int extent_writepages(struct extent_io_tree *tree,
-		      struct address_space *mapping,
+int extent_writepages(struct address_space *mapping,
 		      struct writeback_control *wbc)
 {
 	int ret = 0;
 	struct extent_page_data epd = {
 		.bio = NULL,
-		.tree = tree,
+		.tree = &BTRFS_I(mapping->host)->io_tree,
 		.extent_locked = 0,
 		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
 	};