From: Roger Pau Monne <roger.pau@citrix.com>
Date: Mon, 12 Aug 2013 10:53:43 +0000 (+0200)
Subject: xen-blkfront: improve aproximation of required grants per request
X-Git-Tag: v3.13-rc1~100^2~38
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c47206e25f28232ff979994c32758c82841d81cd;p=pandora-kernel.git

xen-blkfront: improve aproximation of required grants per request

Improve the calculation of required grants to process a request by
using nr_phys_segments instead of always assuming a request is going
to use all posible segments.

nr_phys_segments contains the number of scatter-gather DMA addr+len
pairs, which is basically what we put at every granted page.
for_each_sg iterates over the DMA addr+len pairs and uses a grant
page for each of them.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

Reading git-diff-tree failed