btrfs: drop gfp_t from lock_extent

 lock_extent and unlock_extent are always called with GFP_NOFS, drop the
 argument and use GFP_NOFS consistently.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 73ccadc..69ef456 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -332,7 +332,7 @@
 		return 0;
 
 	lock_extent_bits(io_tree, eb->start, eb->start + eb->len - 1,
-			 0, &cached_state, GFP_NOFS);
+			 0, &cached_state);
 	if (extent_buffer_uptodate(io_tree, eb, cached_state) &&
 	    btrfs_header_generation(eb) == parent_transid) {
 		ret = 0;