--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1052,6 +1052,10 @@ struct btrfs_fs_info {
 	struct btrfs_work qgroup_rescan_work;
 	bool qgroup_rescan_running;	/* protected by qgroup_rescan_lock */
 
+	/* relocation recovery items */
+	bool relocation_recovery_started;
+	struct completion relocation_recovery_completion;
+
 	/* filesystem state */
 	unsigned long fs_state;
 
@@ -3671,7 +3675,8 @@ int btrfs_init_reloc_root(struct btrfs_t
 			  struct btrfs_root *root);
 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
 			    struct btrfs_root *root);
-int btrfs_recover_relocation(struct btrfs_root *root);
+int btrfs_recover_relocation(struct btrfs_fs_info *fs_info);
+void btrfs_wait_for_relocation_completion(struct btrfs_fs_info *fs_info);
 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len);
 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *root, struct extent_buffer *buf,
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2999,7 +2999,7 @@ retry_root_backup:
 			goto fail_qgroup;
 
 		mutex_lock(&fs_info->cleaner_mutex);
-		ret = btrfs_recover_relocation(tree_root);
+		ret = btrfs_recover_relocation(fs_info);
 		mutex_unlock(&fs_info->cleaner_mutex);
 		if (ret < 0) {
 			btrfs_warn(fs_info, "failed to recover relocation: %d",
@@ -3017,7 +3017,8 @@ retry_root_backup:
 	if (IS_ERR(fs_info->fs_root)) {
 		err = PTR_ERR(fs_info->fs_root);
 		btrfs_warn(fs_info, "failed to read fs tree: %d", err);
-		goto fail_qgroup;
+		close_ctree(fs_info);
+		return err;
 	}
 
 	if (sb_rdonly(sb))
@@ -3778,6 +3779,8 @@ void close_ctree(struct btrfs_fs_info *f
 	/* wait for the qgroup rescan worker to stop */
 	btrfs_qgroup_wait_for_completion(fs_info, false);
 
+	btrfs_wait_for_relocation_completion(fs_info);
+
 	/* wait for the uuid_scan task to finish */
 	down(&fs_info->uuid_tree_rescan_sem);
 	/* avoid complains from lockdep et al., set sem back to initial state */
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -22,6 +22,7 @@
 #include <linux/blkdev.h>
 #include <linux/rbtree.h>
 #include <linux/slab.h>
+#include <linux/kthread.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -4492,14 +4493,61 @@ static noinline_for_stack int mark_garba
 }
 
 /*
- * recover relocation interrupted by system crash.
- *
  * this function resumes merging reloc trees with corresponding fs trees.
  * this is important for keeping the sharing of tree blocks
  */
-int btrfs_recover_relocation(struct btrfs_root *root)
+static int
+btrfs_resume_relocation(void *data)
 {
-	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_fs_info *fs_info = data;
+	struct btrfs_trans_handle *trans;
+	struct reloc_control *rc = fs_info->reloc_ctl;
+	int err, ret;
+
+	btrfs_info(fs_info, "resuming relocation");
+
+	BUG_ON(!rc);
+
+	mutex_lock(&fs_info->cleaner_mutex);
+
+	merge_reloc_roots(rc);
+
+	unset_reloc_control(rc);
+
+	trans = btrfs_join_transaction(rc->extent_root);
+	if (IS_ERR(trans))
+		err = PTR_ERR(trans);
+	else {
+		ret = btrfs_commit_transaction(trans);
+		if (ret < 0)
+			err = ret;
+	}
+
+	kfree(rc);
+
+	if (err == 0) {
+		struct btrfs_root *fs_root;
+
+		/* cleanup orphan inode in data relocation tree */
+		fs_root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
+		if (IS_ERR(fs_root))
+			err = PTR_ERR(fs_root);
+		else
+			err = btrfs_orphan_cleanup(fs_root);
+	}
+	mutex_unlock(&fs_info->cleaner_mutex);
+	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+	complete_all(&fs_info->relocation_recovery_completion);
+	return err;
+}
+
+/*
+ * recover relocation interrupted by system crash.
+ * this function locates the relocation trees
+ */
+int btrfs_recover_relocation(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_root *tree_root = fs_info->tree_root;
 	LIST_HEAD(reloc_roots);
 	struct btrfs_key key;
 	struct btrfs_root *fs_root;
@@ -4508,9 +4556,12 @@ int btrfs_recover_relocation(struct btrf
 	struct extent_buffer *leaf;
 	struct reloc_control *rc = NULL;
 	struct btrfs_trans_handle *trans;
+	struct task_struct *tsk;
 	int ret;
 	int err = 0;
 
+	WARN_ON(!rwsem_is_locked(&fs_info->sb->s_umount));
+
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
@@ -4521,8 +4572,7 @@ int btrfs_recover_relocation(struct btrf
 	key.offset = (u64)-1;
 
 	while (1) {
-		ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,
-					path, 0, 0);
+		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 		if (ret < 0) {
 			err = ret;
 			goto out;
@@ -4540,7 +4590,7 @@ int btrfs_recover_relocation(struct btrf
 		    key.type != BTRFS_ROOT_ITEM_KEY)
 			break;
 
-		reloc_root = btrfs_read_fs_root(root, &key);
+		reloc_root = btrfs_read_fs_root(tree_root, &key);
 		if (IS_ERR(reloc_root)) {
 			err = PTR_ERR(reloc_root);
 			goto out;
@@ -4620,16 +4670,21 @@ int btrfs_recover_relocation(struct btrf
 	if (err)
 		goto out_free;
 
-	merge_reloc_roots(rc);
-
-	unset_reloc_control(rc);
-
-	trans = btrfs_join_transaction(rc->extent_root);
-	if (IS_ERR(trans)) {
-		err = PTR_ERR(trans);
+	tsk = kthread_run(btrfs_resume_relocation, fs_info,
+			  "relocation-recovery");
+	if (IS_ERR(tsk)) {
+		err = PTR_ERR(tsk);
 		goto out_free;
 	}
-	err = btrfs_commit_transaction(trans);
+
+	fs_info->relocation_recovery_started = true;
+
+	/* protected from racing with resume thread by the cleaner_mutex */
+	init_completion(&fs_info->relocation_recovery_completion);
+
+	set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
+	return 0;
+
 out_free:
 	kfree(rc);
 out:
@@ -4649,6 +4704,13 @@ out:
 	return err;
 }
 
+void
+btrfs_wait_for_relocation_completion(struct btrfs_fs_info *fs_info)
+{
+	if (fs_info->relocation_recovery_started)
+		wait_for_completion(&fs_info->relocation_recovery_completion);
+}
+
 /*
  * helper to add ordered checksum for data relocation.
  *
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1767,7 +1767,6 @@ static inline void btrfs_remount_cleanup
 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
-	struct btrfs_root *root = fs_info->tree_root;
 	unsigned old_flags = sb->s_flags;
 	unsigned long old_opts = fs_info->mount_opt;
 	unsigned long old_compress_type = fs_info->compress_type;
@@ -1834,6 +1833,8 @@ static int btrfs_remount(struct super_bl
 		btrfs_scrub_cancel(fs_info);
 		btrfs_pause_balance(fs_info);
 
+		btrfs_wait_for_relocation_completion(fs_info);
+
 		ret = btrfs_commit_super(fs_info);
 		if (ret)
 			goto restore;
@@ -1867,7 +1868,7 @@ static int btrfs_remount(struct super_bl
 
 		/* recover relocation */
 		mutex_lock(&fs_info->cleaner_mutex);
-		ret = btrfs_recover_relocation(root);
+		ret = btrfs_recover_relocation(fs_info);
 		mutex_unlock(&fs_info->cleaner_mutex);
 		if (ret)
 			goto restore;
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4034,6 +4034,12 @@ static int balance_kthread(void *data)
 	struct btrfs_fs_info *fs_info = data;
 	int ret = 0;
 
+	if (fs_info->relocation_recovery_started) {
+		btrfs_info(fs_info,
+			   "waiting for relocation recovery before resuming balance");
+		wait_for_completion(&fs_info->relocation_recovery_completion);
+	}
+
 	mutex_lock(&fs_info->volume_mutex);
 	mutex_lock(&fs_info->balance_mutex);
 
