On Tue, Mar 07, 2017 at 06:42:51AM +0100, Adam Borowski wrote:
> If your filesystem has, eg, data:raid0 metadata:raid1, and you run "btrfs
> balance -dconvert=raid1", the meta.target field will be uninitialized.
> That's otherwise ok, as it's unused except for this warning.
>
> Thus, let's use the existing set of raid levels for the comparison.
>
> As a side effect, non-convert balances will now nag about data>metadata.
>
> Signed-off-by: Adam Borowski <kilobyte@xxxxxxxxxx>
> ---
> To reproduce:
> dd if=/dev/zero bs=1048576 count=1 seek=4095 of=ra
> dd if=/dev/zero bs=1048576 count=1 seek=4095 of=rb
> mkfs.btrfs ra rb # defaults to -draid0 -mraid1
> losetup -f ra
> losetup -f rb
> mount /dev/loop0 /mnt/vol1
> btrfs balance start -dconvert=raid1 /mnt/vol1
>
> fs/btrfs/volumes.c | 5 +++++
> 1 file changed, 5 insertions(+)
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 3645af2749f8..c016db81ba43 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -3846,6 +3846,11 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
> }
> } while (read_seqretry(&fs_info->profiles_lock, seq));
>
> + /* if we're not converting, the target field is uninitialized */
> + if (!(bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT))
> + bctl->meta.target = fs_info->avail_metadata_alloc_bits;
> + if (!(bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT))
> + bctl->data.target = fs_info->avail_data_alloc_bits;
This looks good, but this also brings another side effect, @bctl would
also be kept in balance_item which will be used to resume balance in
case of crash, so it may see a different bctl->meta.target.
So would you please use local varibles for meta.target and data.target?
Thanks,
-liubo
> if (btrfs_get_num_tolerated_disk_barrier_failures(bctl->meta.target) <
> btrfs_get_num_tolerated_disk_barrier_failures(bctl->data.target)) {
> btrfs_warn(fs_info,
> --
> 2.11.0
>
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