dm raid: reject too many write_mostly devices

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 0eceee802571..a38298589db8 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1025,7 +1025,7 @@ static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
 {
         int value, raid10_format = ALGORITHM_RAID10_DEFAULT;
         unsigned raid10_copies = 2;
-        unsigned i;
+        unsigned i, write_mostly = 0;
         unsigned region_size = 0;
         sector_t max_io_len;
         const char *arg, *key;
@@ -1179,6 +1179,7 @@ static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
                                 return -EINVAL;
                         }
 
+                        write_mostly++;
                         set_bit(WriteMostly, &rs->dev[value].rdev.flags);
                         set_bit(__CTR_FLAG_WRITE_MOSTLY, &rs->ctr_flags);
                 } else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND))) {
@@ -1303,6 +1304,11 @@ static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
                 return -EINVAL;
         }
 
+        if (write_mostly >= rs->md.raid_disks) {
+                rs->ti->error = "Can't set all raid1 devices to write_mostly";
+                return -EINVAL;
+        }
+
         if (validate_region_size(rs, region_size))
                 return -EINVAL;