From: Milan Broz <mbroz@redhat.com>
Date: Fri, 10 Oct 2008 12:37:08 +0000 (+0100)
Subject: dm crypt: avoid unnecessary wait when splitting bio
X-Git-Tag: v2.6.28-rc1~729^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=933f01d43326fb12a978a8e0bb062c28a2de4d5a;p=pandora-kernel.git

dm crypt: avoid unnecessary wait when splitting bio

Don't wait between submitting crypt requests for a bio unless
we are short of memory.

There are two situations when we must split an encrypted bio:
  1) there are no free pages;
  2) the new bio would violate underlying device restrictions
(e.g. max hw segments).

In case (2) we do not need to wait.

Add output variable to crypt_alloc_buffer() to distinguish between
these cases.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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