btrfs: drop unused argument from extent_io_tree_init

all callers pass GFP_NOFS, but the GFP mask argument is not used in the
function; GFP_ATOMIC is passed to radix tree initialization and it's the
only correct one, since we're using the preload/insert mechanism of
radix tree.
Let's drop the gfp mask from btrfs function, this will not change
behaviour.

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 25e4b8f..3ce80f7 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1080,7 +1080,7 @@
 	root->log_transid = 0;
 	root->last_log_commit = 0;
 	extent_io_tree_init(&root->dirty_log_pages,
-			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+			     fs_info->btree_inode->i_mapping);
 
 	memset(&root->root_key, 0, sizeof(root->root_key));
 	memset(&root->root_item, 0, sizeof(root->root_item));
@@ -1712,8 +1712,7 @@
 
 	RB_CLEAR_NODE(&BTRFS_I(fs_info->btree_inode)->rb_node);
 	extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
-			     fs_info->btree_inode->i_mapping,
-			     GFP_NOFS);
+			     fs_info->btree_inode->i_mapping);
 	extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
 			     GFP_NOFS);
 
@@ -1729,9 +1728,9 @@
 	fs_info->block_group_cache_tree = RB_ROOT;
 
 	extent_io_tree_init(&fs_info->freed_extents[0],
-			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+			     fs_info->btree_inode->i_mapping);
 	extent_io_tree_init(&fs_info->freed_extents[1],
-			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+			     fs_info->btree_inode->i_mapping);
 	fs_info->pinned_extents = &fs_info->freed_extents[0];
 	fs_info->do_barriers = 1;