On Mon, Apr 22, 2019 at 04:44:09PM +0100, fdmanana@xxxxxxxxxx wrote:
> From: Filipe Manana <fdmanana@xxxxxxxx>
> --- a/fs/btrfs/send.c
> +++ b/fs/btrfs/send.c
> @@ -6869,9 +6869,23 @@ 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,
> + "Can not run send because a balance operation is in progress");
> + ret = -EAGAIN;
> + goto out;
> + }
> + fs_info->send_in_progress++;
> + mutex_unlock(&fs_info->balance_mutex);
This would be better in a helper that hides that the balance mutex from
send.
eg.
if (!btrfs_send_can_start(fs_info)
return -EAGAIN;
> +
> 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);
btrfs_send_end();
> if (ret < 0)
> goto out;
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index db934ceae9c1..8145b62e3912 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -4203,6 +4203,14 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
> get_raid_name(meta_index), get_raid_name(data_index));
> }
>
> + if (fs_info->send_in_progress) {
> + btrfs_warn_rl(fs_info,
> +"Can not run balance while send operations are in progress (%d in progress)",
> + fs_info->send_in_progress);
> + ret = -EAGAIN;
> + goto out;
> + }
Similar here.
As the operation compatibility is done on the filesystem level, it would
be better to hide all the logic in helpers, now that there's more than
the per-subvolume send_in_progress.
