From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?windows-1252?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>
Subject: Re: [PATCH 12/14] xen-blkback: safely unmap grants in
 case they are still in use
Date: Fri, 23 Jan 2015 15:41:43 +0100
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To: David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xenproject.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>, Jenny Herbert <jennifer.herbert@citrix.com>
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El 23/01/15 a les 13.02, David Vrabel ha escrit:
> On 19/01/15 15:51, David Vrabel wrote:
>> From: Jenny Herbert <jennifer.herbert@citrix.com>
>>
>> Use gnttab_unmap_refs_async() to wait until the mapped pages are no
>> longer in use before unmapping them.
>>
>> This allows blkback to use network storage which may retain refs to
>> pages in queued skbs after the block I/O has completed.
> 
> Roger, I'd appreciate a review of this blkback change.

Done. BTW, have you tested the patch setting:

# echo 128 > /sys/module/xen_blkback/parameters/max_persistent_grants

Without this some of the newly introduced code-paths would remain
untested (replace 128 with whatever you want, or even 0).

Roger.