btrfs: balance: print to system log when balance ends or is paused

Print a kernel log message when the balance ends, either for cancel or
completed or if it is paused.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -4287,6 +4287,13 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
 	ret = __btrfs_balance(fs_info);
 
 	mutex_lock(&fs_info->balance_mutex);
+	if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req))
+		btrfs_info(fs_info, "balance: paused");
+	else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req))
+		btrfs_info(fs_info, "balance: canceled");
+	else
+		btrfs_info(fs_info, "balance: ended with status: %d", ret);
+
 	clear_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags);
 
 	if (bargs) {