From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Date: Tue, 6 Jan 2009 03:05:07 +0000 (+0000)
Subject: dm request: extend target interface
X-Git-Tag: v2.6.29-rc1~492^2~8
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d76345da6ed3927c9cbf5d3f7a7021e8bba7374;p=pandora-kernel.git

dm request: extend target interface

This patch adds the following target interfaces for request-based dm.

  map_rq    : for mapping a request

  rq_end_io : for finishing a request

  busy      : for avoiding performance regression from bio-based dm.
              Target can tell dm core not to map requests now, and
              that may help requests in the block layer queue to be
              bigger by I/O merging.
              In bio-based dm, this behavior is done by device
              drivers managing the block layer queue.
              But in request-based dm, dm core has to do that
              since dm core manages the block layer queue.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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