Re: [PATCH v2 3/4] xen-blkback: check the number of iovecs beforeallocating a bios

From: Roger Pau Monné
Date: Tue Jun 25 2013 - 04:03:48 EST


On 24/06/13 15:28, Konrad Rzeszutek Wilk wrote:
> On Sat, Jun 22, 2013 at 09:59:17AM +0200, Roger Pau Monne wrote:
>> With the introduction of indirect segments we can receive requests
>> with a number of segments bigger than the maximum number of allowed
>> iovecs in a bios, so make sure that blkback doesn't try to allocate a
>> bios with more iovecs than BIO_MAX_PAGES
>
> Shouldn't we just gate the feature-indirect-descriptor value to
> take this into account?
>
> What happens if the nseg is > BIO_MAX_PAGES? Do we "lose" the request
> for the remaining segments?

No, we just allocate several bios in order to send the request to the
underlying device.
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