[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block |
Date: |
Mon, 12 Feb 2018 15:32:28 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 12/02/2018 15:30, Kevin Wolf wrote:
>>> We shouldn't be adding new instances of BLOCK_OP_* at all. I couldn't
>>> find the time yet to remove the existing ones, but any new protections
>>> should be using the permission system.
>> I agree. But does this include not fixing bugs wherever clients are
>> using the old op blockers?
> I'm not saying that we shouldn't fix the bug, just that we should fix it
> properly with the best infrastructure we have.
>
> The old op blockers are "fixing" the problem at the symptom level, and
> you have to check for each high-level operation if it does something
> problematic internally. You have to repeat this analysis every time you
> add a new operation or modifiy an existing one (which noone ever does).
> The risk that this breaks sooner or later is pretty high.
>
> The new permission system, on the other hand, directly addresses the
> root cause, and any new feature that uses dirty bitmaps will then
> automatically get the protection, too.
>
> So in fact, I would say that the bug isn't really fixed (but at best
> papered over) until we add a proper fix on the permission level.
Okay, we are in agreement about this and you expressed very well why I
(at the gut feeling level) didn't like the old op blockers. But you
bypassed the real question, which is: should I send a pull request for
these two patches or not? :)
Paolo
- [Qemu-block] [PATCH 0/2] scsi: add block job opblockers for scsi-block, Paolo Bonzini, 2018/02/07
- [Qemu-block] [PATCH 1/2] scsi: add unrealize method for SCSI devices, Paolo Bonzini, 2018/02/07
- [Qemu-block] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Paolo Bonzini, 2018/02/07
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Fam Zheng, 2018/02/07
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Paolo Bonzini, 2018/02/08
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Kevin Wolf, 2018/02/12
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Paolo Bonzini, 2018/02/12
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Kevin Wolf, 2018/02/12
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block,
Paolo Bonzini <=
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Kevin Wolf, 2018/02/12
- Re: [Qemu-block] [Qemu-devel] [PATCH 2/2] scsi: add block job opblockers for scsi-block, Paolo Bonzini, 2018/02/12