btrfs-progs: add trans_lock to fs_info

This exists in the kernel, and is touched by ctree.c, add it to the
btrfs_fs_info to make syncing ctree.c more straightforward.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

kernel-shared/ctree.h

@@ -328,6 +328,8 @@ struct btrfs_fs_info {
 	struct extent_io_tree extent_ins;
 	struct extent_io_tree *excluded_extents;
 
+	spinlock_t trans_lock;
+
 	struct rb_root block_group_cache_tree;
 	/* logical->physical extent mapping */
 	struct btrfs_mapping_tree mapping_tree;

kernel-shared/disk-io.c

@@ -878,6 +878,8 @@ struct btrfs_fs_info *btrfs_new_fs_info(int writable, u64 sb_bytenr)
 	INIT_LIST_HEAD(&fs_info->space_info);
 	INIT_LIST_HEAD(&fs_info->recow_ebs);
 
+	spin_lock_init(&fs_info->trans_lock);
+
 	if (!writable)
 		fs_info->readonly = 1;