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Re: [Qemu-block] Broken aarch64 by qcow2: skip writing zero buffers to e
Re: [Qemu-block] Broken aarch64 by qcow2: skip writing zero buffers to empty COW areas [v2]
Wed, 21 Aug 2019 15:49:23 +0000
On 21/8/2019 5:14 PM, Lukáš Doktor wrote:
> Hello guys,
> First attempt was rejected due to zip attachment, let's try it again with
> just Avocado-vt debug.log and serial console log files attached.
> I bisected a regression on aarch64 all the way to this commit: "qcow2: skip
> writing zero buffers to empty COW areas"
> c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. Would you please have a look at it?
> My reproducer is running kickstart installation of RHEL-8 from DVD on aarch64
> gicv3 machine, which never finishes since this commit, where anaconda
> complains about package installation, occasionally there are also XFS
> metadata corruption messages on serial console:
this looks scary :( I doubt that it can have anything to do with aarch64
but rather a really tricky timing (or, possibly, a broken environment
like broken fallocate() on a host? who knows..)
Is it always the same machine you observe this issue on? Did you try
I just wonder if it's worth to try to reproduce it on my machine
(and I don't have aarch64 on hand now). I can probably come up with
some torture test that will continuously write to qcow2 with random
offsets/sizes and verify the result.
If you could kindly reproduce it again then we can probably start with
enabling qemu traces by appending
" -trace bdrv* -trace qcow2* -trace file=/some_huge_partition/qemu.log"
to the command line.
Beware that it's going to produce a huge amount of logs.
Also, the corrupted image and the serial log will be required for