md/raid1: Fix assembling of arrays containing Replacements.

commit 02b898f2f04e418094f0093a3ad0b415bcdbe8eb upstream.

setup_conf in raid1.c uses conf->raid_disks before assigning
a value.  It is used when including 'Replacement' devices.

The consequence is that assembling an array which contains a
replacement will misbehave and either not include the replacement, or
not include the device being replaced.

Though this doesn't lead directly to data corruption, it could lead to
reduced data safety.

So use mddev->raid_disks, which is initialised, instead.

Bug was introduced by commit c19d57980b38a5bb613a898937a1cf85f422fb9b
      md/raid1: recognise replacements when assembling arrays.

in 3.3, so fix is suitable for 3.3.y thru 3.6.y.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 611b5f79761826f8843ede2384c47ccbd0a87be1..05bb49e13648267d21a02efb698db165d0180026 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2699,7 +2699,7 @@ static struct r1conf *setup_conf(struct mddev *mddev)
                    || disk_idx < 0)
                        continue;
                if (test_bit(Replacement, &rdev->flags))
-                       disk = conf->mirrors + conf->raid_disks + disk_idx;
+                       disk = conf->mirrors + mddev->raid_disks + disk_idx;
                else
                        disk = conf->mirrors + disk_idx;