Re: [PATCH v4 0/6] Chunk level degradable check

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2017年07月12日 23:24, David Sterba wrote:
> On Wed, Jun 28, 2017 at 01:43:29PM +0800, Qu Wenruo wrote:
>> The patchset can be fetched from my github repo:
>> https://github.com/adam900710/linux/tree/degradable
>>
>> The patchset is based on David's for-4.13-part1 branch.
>>
>> Btrfs currently uses num_tolerated_disk_barrier_failures to do global
>> check for tolerated missing device.
>>
>> Although the one-size-fit-all solution is quite safe, it's too strict
>> if data and metadata has different duplication level.
>>
>> For example, if one use Single data and RAID1 metadata for 2 disks, it
>> means any missing device will make the fs unable to be degraded
>> mounted.
>>
>> But in fact, some times all single chunks may be in the existing
>> device and in that case, we should allow it to be rw degraded mounted.
>>
>> Such case can be easily reproduced using the following script:
>>   # mkfs.btrfs -f -m raid1 -d sing /dev/sdb /dev/sdc
>>   # wipefs -f /dev/sdc
>>   # mount /dev/sdb -o degraded,rw
> 
> I've seen wider testing coverage in replies to the previous patchset
> iterations. Can we have that added to fstests?

I'm completely OK to add fstests test case.
While the concern is still the same: we need better wrapper to detect 
chunk layout.

Or we can only have static test case to test chunk-level degradable check.

Thanks,
Qu

> 
> I'm going to add this patchset to the devel queue (ie. not a separate
> for-next branch anymore).
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