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-Tag: firefly_0821_release~10186^2~391
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=62ead775d1932164b7113618800d87aed9fa0ac5;p=firefly-linux-kernel-4.4.55.git

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

commit 8f5f02c460b7ca74ce55ce126ce0c1e58a3f923d upstream.

'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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 68bfb68af5ad..697a2c7bff2c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -305,6 +305,9 @@ 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);