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Date: Wed, 20 Jan 2010 08:56:23 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH] block: prevent multiwrite_merge from creating
	too large iovecs
References: <20100119211539.GA4383@lst.de>
In-Reply-To: <20100119211539.GA4383@lst.de>
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To: Christoph Hellwig <hch@lst.de>
Cc: qemu-devel@nongnu.org

On 01/19/2010 03:15 PM, Christoph Hellwig wrote:
> 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>
>    

Applied.  Thanks.

Regards,

Anthony Liguori
> Index: qemu/block.c
> ===================================================================
> --- qemu.orig/block.c	2010-01-19 22:10:19.797003226 +0100
> +++ qemu/block.c	2010-01-19 22:11:08.226005767 +0100
> @@ -1711,6 +1711,10 @@ static int multiwrite_merge(BlockDriverS
>               merge = bs->drv->bdrv_merge_requests(bs,&reqs[outidx],&reqs[i]);
>           }
>
> +        if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1>  IOV_MAX) {
> +            merge = 0;
> +        }
> +
>           if (merge) {
>               size_t size;
>               QEMUIOVector *qiov = qemu_mallocz(sizeof(*qiov));
>
>
>
>