MD RAID10: Prep for DM RAID10 device replacement capability

MD RAID10:  Fix a couple potential kernel panics if RAID10 is used by dm-raid

When device-mapper uses the RAID10 personality through dm-raid.c, there is no
'gendisk' structure in mddev and some sysfs information is also not populated.

This patch avoids touching those non-existent structures.

Signed-off-by: Jonathan Brassow <jbrassow@rehdat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index feab588adb50..85e6786653ea 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2044,8 +2044,14 @@ EXPORT_SYMBOL(md_integrity_register);
 /* Disable data integrity if non-capable/non-matching disk is being added */
 void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
 {
-        struct blk_integrity *bi_rdev = bdev_get_integrity(rdev->bdev);
-        struct blk_integrity *bi_mddev = blk_get_integrity(mddev->gendisk);
+        struct blk_integrity *bi_rdev;
+        struct blk_integrity *bi_mddev;
+
+        if (!mddev->gendisk)
+                return;
+
+        bi_rdev = bdev_get_integrity(rdev->bdev);
+        bi_mddev = blk_get_integrity(mddev->gendisk);
 
         if (!bi_mddev) /* nothing to do */
                 return;