From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: [PATCH v5 01/11] block: make generic_make_request
	handle	arbitrarily sized bios
Date: Fri, 7 Aug 2015 09:30:01 +0200
Message-ID: <20150807073001.GA17485@lst.de>
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	<1438581502.26596.24.camel@hasee> <20150804113626.GA12682@lst.de>
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To: Ming Lin <mlin-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Neil Brown <neilb-l3A5Bk7waGM@public.gmane.org>, Ming Lei <ming.lei-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>, Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Lars Ellenberg <drbd-dev-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org>, Philip Kelleher <pjk1939-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Kent Overstreet <kent.overstreet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Nitin Gupta <ngupta-KNmc09w0p+Ednm+yROfE0A@public.gmane.org>, Ming Lin <ming.l-Vzezgt5dB6uUEJcrhfAQsw@public.gmane.org>, Oleg Drokin <oleg.drokin-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>, Andreas Dilger <andreas.dilger-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Geoff Levand <geoff-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Jiri Kosina <jkosina-AlSwsSmVLrQ@public.gmane.org>, lkml <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Jim Paris <jim-XrPbb/hENzg@public.gmane.org>, Minchan Kim <minchan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Dongsu Park <dpark-VwIFZPTo/vqsTnJN9+BGXg@public.gmane.org>, drbd-user-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org
List-Id: dm-devel.ids

I'm for solution 3:

 - keep blk_bio_{discard,write_same}_split, but ensure we never built
   a > 4GB bio in blkdev_issue_{discard,write_same}.

Note that this isn't special casing, we can't build > 4GB bios for
data either, it's just implemented as a side effect right now instead
of checked explicitly.