From: Milan Broz <mbroz@redhat.com>
Date: Thu, 12 Jul 2007 16:28:00 +0000 (+0100)
Subject: dm snapshot: fix invalidation deadlock
X-Git-Tag: v2.6.23-rc1~1094
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fcac03abd325e4f7a4cc8fe05fea2793b1c8eb75;p=pandora-kernel.git

dm snapshot: fix invalidation deadlock

Process persistent exception store metadata IOs in a separate thread.

A snapshot may become invalid while inside generic_make_request().
A synchronous write is then needed to update the metadata while still
inside that function.  Since the introduction of
md-dm-reduce-stack-usage-with-stacked-block-devices.patch this has to
be performed by a separate thread to avoid deadlock.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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