From: Neil Brown <neilb@suse.de>
Date: Wed, 7 Jan 2009 07:55:39 +0000 (+0100)
Subject: block: fix bug in ptbl lookup cache
X-Git-Tag: v2.6.29-rc1~28^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54b0d127696aba2ef1ec5430301c968ab539fa0d;p=pandora-kernel.git

block: fix bug in ptbl lookup cache

Neil writes:

   Hi Jens,

    I've found a little bug for you.  It was introduced by
        a6f23657d3072bde6844055bbc2290e497f33fbc

        block: add one-hit cache for disk partition lookup

    and has the effect of killing my machine whenever I try to assemble
    an md array :-(
    One of the devices in the array has partitions, and mdadm always
    deletes partitions before putting a whole-device in an array (as it
    can cause confusion).  The next IO to that device locks the machine.
    I don't really understand exactly why it locks up, but it happens in
    disk_map_sector_rcu().  This patch fixes it.

Which is due to a missing clear of the (now) stale partition lookup
data. So clear that when we delete a partition.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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