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Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb |
Date: |
Thu, 22 Aug 2013 13:15:59 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 |
Il 22/08/2013 12:28, Bharata B Rao ha scritto:
> On Thu, Aug 22, 2013 at 12:00:48PM +0200, Paolo Bonzini wrote:
>> Il 22/08/2013 11:55, Bharata B Rao ha scritto:
>>> This was the first apporach I had. I used to abort when writes to pipe
>>> fail. But there were concerns raised about handling the failures gracefully
>>> and hence we ended up doing all that error handling of completing the aio
>>> with -EIO, closing the pipe and making the disk inaccessible.
>>>
>>>>> Under what circumstances could it happen?
>>> Not very sure, I haven't seen that happening. I had to manually inject
>>> faults to test this error path and verify the graceful recovery.
>>
>> Looking at write(2), it looks like it is impossible
>>
>> EAGAIN or EWOULDBLOCK
>> can't happen, blocking file descriptor
>>
>> EBADF, EPIPE
>> shouldn't happen since the device is drained before
>> calling qemu_gluster_close.
>>
>> EDESTADDRREQ, EDQUOT, EFBIG, EIO, ENOSPC
>> cannot happen for pipes
>>
>> EFAULT
>> abort would be fine
>
> In the case where we have separate system and data disks and if error (EFAULT)
> happens for the data disk, don't we want to keep the VM up by gracefully
> disabling IO to the data disk ?
EFAULT means the buffer address is invalid, I/O error would be EIO, but...
> I remember this was one of the motivations to
> handle this failure.
... this write is on the pipe, not on a disk.
Paolo
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, (continued)
Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Stefan Hajnoczi, 2013/08/21
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Paolo Bonzini, 2013/08/21
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Stefan Hajnoczi, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Paolo Bonzini, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Paolo Bonzini, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Paolo Bonzini, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/22
- Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Paolo Bonzini, 2013/08/22
Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/23
Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Paolo Bonzini, 2013/08/23
Re: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb, Bharata B Rao, 2013/08/23