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Date: Wed, 20 Jan 2010 17:29:25 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block: prevent multiwrite_merge from creating
	too large iovecs
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To: Christoph Hellwig <hch@lst.de>
Cc: qemu-devel@nongnu.org

Am 20.01.2010 17:24, schrieb Christoph Hellwig:
> On Wed, Jan 20, 2010 at 12:37:51PM +0100, Kevin Wolf wrote:
>> Am 19.01.2010 22:15, schrieb Christoph Hellwig:
>>> If we go over the maximum number of iovecs support by syscall we get
>>> back EINVAL from the kernel which translate to I/O errors for the guest.
>>>
>>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>>
>> Is this really enough? We don't check for IOV_MAX in any other place, so
>> can't we get a too big request directly from virtio-blk?
> 
> Currently the virtqueue is limited to 1024 iovecs, but I plan to put in
> some better infrastructure to deal with the queue limit.  For now this
> patch fixes an issue that we see with real life setups.

Ok, if you're planning to replace it by something real, I'm not opposed
to using this as a quick fix for the meantime. However, it needs an
#ifdef for the mingw build breakage at least.

Kevin