dm-snap: simplify the origin_dev == cow_dev check in snapshot_ctr

Use the block_device acquired in dm_get_device for the check instead
of doing an extra lookup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@kernel.org>
Link: https://lore.kernel.org/r/20230531125535.676098-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 9c49f53..7832974 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1241,7 +1241,6 @@ 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 int args_used, num_flush_bios = 1;
        fmode_t origin_mode = FMODE_READ;
 
@@ -1279,24 +1278,21 @@ 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";
                goto bad_cow;
        }
+       if (s->cow->bdev && s->cow->bdev == s->origin->bdev) {
+               ti->error = "COW device cannot be the same as origin device";
+               r = -EINVAL;
+               goto bad_store;
+       }
 
        r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store);
        if (r) {