4 files changed, 31 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 31198499f175..02a29516dacf 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -793,6 +793,7 @@ enum {
 	/*
 	 * Indicate that balance has been set up from the ioctl and is in the
 	 * main phase. The fs_info::balance_ctl is initialized.
+	 * Set and cleared while holding fs_info::balance_mutex.
 	 */
 	BTRFS_FS_BALANCE_RUNNING,
 
@@ -1175,6 +1176,12 @@ struct btrfs_fs_info {
 
 	struct crypto_shash *csum_shash;
 
+	/*
+	 * Number of send operations in progress.
+	 * Updated while holding fs_info::balance_mutex.
+	 */
+	int send_in_progress;
+
 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 	spinlock_t ref_verify_lock;
 	struct rb_root block_tree;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6c7dc24d4031..41a2bd2e0c56 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2809,6 +2809,8 @@ int open_ctree(struct super_block *sb,
 	spin_lock_init(&fs_info->swapfile_pins_lock);
 	fs_info->swapfile_pins = RB_ROOT;
 
+	fs_info->send_in_progress = 0;
+
 	ret = btrfs_alloc_stripe_hash_table(fs_info);
 	if (ret) {
 		err = ret;
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 49edcc709a99..69b59bf75882 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -6929,9 +6929,23 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 	if (ret)
 		goto out;
 
+	mutex_lock(&fs_info->balance_mutex);
+	if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
+		mutex_unlock(&fs_info->balance_mutex);
+		btrfs_warn_rl(fs_info,
+		"cannot run send because a balance operation is in progress");
+		ret = -EAGAIN;
+		goto out;
+	}
+	fs_info->send_in_progress++;
+	mutex_unlock(&fs_info->balance_mutex);
+
 	current->journal_info = BTRFS_SEND_TRANS_STUB;
 	ret = send_subvol(sctx);
 	current->journal_info = NULL;
+	mutex_lock(&fs_info->balance_mutex);
+	fs_info->send_in_progress--;
+	mutex_unlock(&fs_info->balance_mutex);
 	if (ret < 0)
 		goto out;
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9e5167a0e406..41813813f840 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4161,6 +4161,14 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
 				btrfs_bg_type_to_raid_name(data_target));
 	}
 
+	if (fs_info->send_in_progress) {
+		btrfs_warn_rl(fs_info,
+"cannot run balance while send operations are in progress (%d in progress)",
+			      fs_info->send_in_progress);
+		ret = -EAGAIN;
+		goto out;
+	}
+
 	ret = insert_balance_item(fs_info, bctl);
 	if (ret && ret != -EEXIST)
 		goto out;