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Re: [Qemu-devel] Fwd: qemu drive mirror assert fault
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] Fwd: qemu drive mirror assert fault |
Date: |
Tue, 05 May 2015 15:07:31 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 05/05/2015 15:03, Kevin Wolf wrote:
> > Yes, the SCSI command WRITE SAME with UNMAP = 1 (not coincidentially :))
> > calls discard too. Who knows what the guest used it for...
> >
> > However, write zeroes doesn't go through bdrv_co_discard, does it?
>
> Initially I expected that it does, but when I checked, it turned out
> that it uses a different path. The only thing I found that really uses
> discard is the call in qemu-img that I mentioned. But that can't be the
> cause of the corruption you're debugging.
I'm not seeing corruption; it's a crash in drive-mirror.
The question is how to treat discard:
1) mark sectors as dirty, discard on the destination as well (similar to
Fam's just-posted patches, but they do not discard on the destination)
2) keep marking sectors as not dirty, change util/hbitmap.c to avoid the
assertion failure. This loses the discard on the destination but no
need to change block/mirror.c
Both are valid approaches.
Paolo
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Fam Zheng, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Paolo Bonzini, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Fam Zheng, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Kevin Wolf, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Paolo Bonzini, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Paolo Bonzini, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Kevin Wolf, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault,
Paolo Bonzini <=
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Kevin Wolf, 2015/05/05
- Re: [Qemu-devel] Fwd: qemu drive mirror assert fault, Fam Zheng, 2015/05/05