Btrfs: remove unnecessary transaction commit before send

We will finish orphan cleanups during snapshot, so we don't
have to commit transaction here.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/send.c

@@ -4775,35 +4775,6 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 	 */
 	WARN_ON(send_root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE);
 
-	/*
-	 * If we just created this root we need to make sure that the orphan
-	 * cleanup has been done and committed since we search the commit root,
-	 * so check its commit root transid with our otransid and if they match
-	 * commit the transaction to make sure everything is updated.
-	 */
-	down_read(&send_root->fs_info->extent_commit_sem);
-	if (btrfs_header_generation(send_root->commit_root) ==
-	    btrfs_root_otransid(&send_root->root_item)) {
-		struct btrfs_trans_handle *trans;
-
-		up_read(&send_root->fs_info->extent_commit_sem);
-
-		trans = btrfs_attach_transaction_barrier(send_root);
-		if (IS_ERR(trans)) {
-			if (PTR_ERR(trans) != -ENOENT) {
-				ret = PTR_ERR(trans);
-				goto out;
-			}
-			/* ENOENT means theres no transaction */
-		} else {
-			ret = btrfs_commit_transaction(trans, send_root);
-			if (ret)
-				goto out;
-		}
-	} else {
-		up_read(&send_root->fs_info->extent_commit_sem);
-	}
-
 	/*
 	 * Userspace tools do the checks and warn the user if it's
 	 * not RO.