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Date: Fri, 21 Apr 2017 12:46:22 +0100
From: Roger Pau Monne <roger.pau@citrix.com>
To: Christoph Hellwig <hch@infradead.org>
CC: NeilBrown <neilb@suse.com>, Jens Axboe <axboe@kernel.dk>,
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Subject: Re: [PATCH 08/11] xen-blkfront: remove bio splitting.
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On Fri, Apr 21, 2017 at 04:36:20AM -0700, Christoph Hellwig wrote:
> Btw, I really don't understand why this code even looks at bios over
> just requeueing the request.  Can someone explain that bit to me?

This was done because Linux could migrate from a host supporting indirect
descriptors to a host not supporting them, and so the maximum number of
segments per request could change, and the requests already on the queue might
need to be split.

Roger.