diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7eb2913..bf0751d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -800,6 +800,7 @@ struct btrfs_fs_info {
 	struct mutex cleaner_mutex;
 	struct mutex chunk_mutex;
 	struct mutex volume_mutex;
+	struct rw_semaphore bg_delete_sem;
 
 	/*
 	 * this is taken to make sure we don't set block groups ro after
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 60ce119..f8609fd 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2683,6 +2683,7 @@ int open_ctree(struct super_block *sb,
 	init_rwsem(&fs_info->commit_root_sem);
 	init_rwsem(&fs_info->cleanup_work_sem);
 	init_rwsem(&fs_info->subvol_sem);
+	init_rwsem(&fs_info->bg_delete_sem);
 	sema_init(&fs_info->uuid_tree_rescan_sem, 1);
 
 	btrfs_init_dev_replace_locks(fs_info);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index df8d756..50b440e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4111,6 +4111,7 @@ int btrfs_alloc_data_chunk_ondemand(struct inode *inode, u64 bytes)
 	int ret = 0;
 	int need_commit = 2;
 	int have_pinned_space;
+	int have_bg_delete_sem = 0;
 
 	/* make sure bytes are sectorsize aligned */
 	bytes = ALIGN(bytes, root->sectorsize);
@@ -4121,8 +4122,11 @@ int btrfs_alloc_data_chunk_ondemand(struct inode *inode, u64 bytes)
 	}
 
 	data_sinfo = fs_info->data_sinfo;
-	if (!data_sinfo)
+	if (!data_sinfo) {
+		down_read(&root->fs_info->bg_delete_sem);
+		have_bg_delete_sem = 1;
 		goto alloc;
+	}
 
 again:
 	/* make sure we have enough space to handle the data first */
@@ -4135,6 +4139,19 @@ again:
 		struct btrfs_trans_handle *trans;
 
 		/*
+		 * We may need to allocate new chunk, so we should block
+		 * btrfs_delete_unused_bgs()
+		 */
+		if (!have_bg_delete_sem) {
+			spin_unlock(&data_sinfo->lock);
+			down_read(&root->fs_info->bg_delete_sem);
+			have_bg_delete_sem = 1;
+			spin_lock(&data_sinfo->lock);
+			if (used + bytes <= data_sinfo->total_bytes)
+				goto done;
+		}
+
+		/*
 		 * if we don't have enough free bytes in this space then we need
 		 * to alloc a new chunk.
 		 */
@@ -4156,17 +4173,20 @@ alloc:
 			 * the fs.
 			 */
 			trans = btrfs_join_transaction(root);
-			if (IS_ERR(trans))
+			if (IS_ERR(trans)) {
+				up_read(&root->fs_info->bg_delete_sem);
 				return PTR_ERR(trans);
+			}
 
 			ret = do_chunk_alloc(trans, root->fs_info->extent_root,
 					     alloc_target,
 					     CHUNK_ALLOC_NO_FORCE);
 			btrfs_end_transaction(trans, root);
 			if (ret < 0) {
-				if (ret != -ENOSPC)
+				if (ret != -ENOSPC) {
+					up_read(&root->fs_info->bg_delete_sem);
 					return ret;
-				else {
+				} else {
 					have_pinned_space = 1;
 					goto commit_trans;
 				}
@@ -4200,15 +4220,19 @@ commit_trans:
 			}
 
 			trans = btrfs_join_transaction(root);
-			if (IS_ERR(trans))
+			if (IS_ERR(trans)) {
+				up_read(&root->fs_info->bg_delete_sem);
 				return PTR_ERR(trans);
+			}
 			if (have_pinned_space >= 0 ||
 			    test_bit(BTRFS_TRANS_HAVE_FREE_BGS,
 				     &trans->transaction->flags) ||
 			    need_commit > 0) {
 				ret = btrfs_commit_transaction(trans, root);
-				if (ret)
+				if (ret) {
+					up_read(&root->fs_info->bg_delete_sem);
 					return ret;
+				}
 				/*
 				 * The cleaner kthread might still be doing iput
 				 * operations. Wait for it to finish so that
@@ -4225,13 +4249,19 @@ commit_trans:
 		trace_btrfs_space_reservation(root->fs_info,
 					      "space_info:enospc",
 					      data_sinfo->flags, bytes, 1);
+		up_read(&root->fs_info->bg_delete_sem);
 		return -ENOSPC;
 	}
+
+done:
 	data_sinfo->bytes_may_use += bytes;
 	trace_btrfs_space_reservation(root->fs_info, "space_info",
 				      data_sinfo->flags, bytes, 1);
 	spin_unlock(&data_sinfo->lock);
 
+	if (have_bg_delete_sem)
+		up_read(&root->fs_info->bg_delete_sem);
+
 	return ret;
 }
 
@@ -10594,6 +10624,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 		spin_unlock(&fs_info->unused_bgs_lock);
 
 		mutex_lock(&fs_info->delete_unused_bgs_mutex);
+		down_write(&root->fs_info->bg_delete_sem);
 
 		/* Don't want to race with allocators so take the groups_sem */
 		down_write(&space_info->groups_sem);
@@ -10721,6 +10752,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 end_trans:
 		btrfs_end_transaction(trans, root);
 next:
+		up_write(&root->fs_info->bg_delete_sem);
 		mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 		btrfs_put_block_group(block_group);
 		spin_lock(&fs_info->unused_bgs_lock);
