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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