From: NeilBrown <neilb@suse.de>
Date: Wed, 16 Feb 2011 02:58:51 +0000 (+1100)
Subject: md: correctly handle probe of an 'mdp' device.
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=8f5f02c460b7ca74ce55ce126ce0c1e58a3f923d;p=openwrt%2Fstaging%2Fblogic.git

md: correctly handle probe of an 'mdp' device.

'mdp' devices are md devices with preallocated device numbers
for partitions. As such it is possible to mknod and open a partition
before opening the whole device.

this causes  md_probe() to be called with a device number of a
partition, which in-turn calls mddev_find with such a number.

However mddev_find expects the number of a 'whole device' and
does the wrong thing with partition numbers.

So add code to mddev_find to remove the 'partition' part of
a device number and just work with the 'whole device'.

This patch addresses https://bugzilla.kernel.org/show_bug.cgi?id=28652

Reported-by: hkmaly@bigfoot.com
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: <stable@kernel.org>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 6818ff4aa8d6..330addfe9b77 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -553,6 +553,9 @@ static mddev_t * mddev_find(dev_t unit)
 {
 	mddev_t *mddev, *new = NULL;
 
+	if (unit && MAJOR(unit) != MD_MAJOR)
+		unit &= ~((1<<MdpMinorShift)-1);
+
  retry:
 	spin_lock(&all_mddevs_lock);