From 188a212df1f3a2d7ea9bb0fc0ab4173042c23470 Mon Sep 17 00:00:00 2001
From: Heinz Mauelshagen <heinzm@redhat.com>
Date: Sat, 2 Dec 2017 01:03:59 +0100
Subject: [PATCH] dm raid: add component device size checks to avoid runtime
 failure
Git-commit: 188a212df1f3a2d7ea9bb0fc0ab4173042c23470
Patch-mainline: v4.16-rc1
References: bsc#1093023

Check all component data device sizes versus calculated size.
Reject if device(s) are too small.  Otherwise, MD will fail the
operation by accessing beyond the end of the data device.

An example use-case is that growing bitmap won't fit any more and the MD
runtime will report an error when DM raid should catch this earlier.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/dm-raid.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index ff75324133fb..2bb0ac7c3fba 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1580,6 +1580,24 @@ static sector_t __rdev_sectors(struct raid_set *rs)
 	return 0;
 }
 
+/* Check that calculated dev_sectors fits all component devices. */
+static int _check_data_dev_sectors(struct raid_set *rs)
+{
+	sector_t ds = ~0;
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, &rs->md)
+		if (!test_bit(Journal, &rdev->flags) && rdev->bdev) {
+			ds = min(ds, to_sector(i_size_read(rdev->bdev->bd_inode)));
+			if (ds < rs->md.dev_sectors) {
+				rs->ti->error = "Component device(s) too small";
+				return -EINVAL;
+			}
+		}
+
+	return 0;
+}
+
 /* Calculate the sectors per device and per array used for @rs */
 static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
 {
@@ -1629,7 +1647,7 @@ static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
 	mddev->array_sectors = array_sectors;
 	mddev->dev_sectors = dev_sectors;
 
-	return 0;
+	return _check_data_dev_sectors(rs);
 bad:
 	rs->ti->error = "Target length not divisible by number of data devices";
 	return -EINVAL;
-- 
2.16.3