dm snapshot: disallow the COW and origin devices from being identical

[pandora-kernel.git] / drivers / md / dm-snap.c

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 09c2b4f..6674ebf 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1055,6 +1055,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
        int i;
        int r = -EINVAL;
        char *origin_path, *cow_path;
+       dev_t origin_dev, cow_dev;
        unsigned args_used, num_flush_requests = 1;
        fmode_t origin_mode = FMODE_READ;
 
@@ -1085,11 +1086,19 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                ti->error = "Cannot get origin device";
                goto bad_origin;
        }
+       origin_dev = s->origin->bdev->bd_dev;
 
        cow_path = argv[0];
        argv++;
        argc--;
 
+       cow_dev = dm_get_dev_t(cow_path);
+       if (cow_dev && cow_dev == origin_dev) {
+               ti->error = "COW device cannot be the same as origin device";
+               r = -EINVAL;
+               goto bad_cow;
+       }
+
        r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow);
        if (r) {
                ti->error = "Cannot get COW device";