dm table: fix regression from improper dm_dev_internal.count refcount_t conversion

Multiple refcounts are needed if the device was already added.  The
micro-optimization of setting the refcount to 1 on first added (rather
than fall thru to a common refcount_inc) lost sight of the fact that the
refcount_inc is also needed for the case when the device already exists
and the mode need not be upgraded.

Fixes: 2a0b4682e0 ("dm: convert dm_dev_internal.count from atomic_t to refcount_t")
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 88130b5d95f909ead8441dec7f3fb5d80a7914c7..aaffd0c0ee9a76c71f23f9bb1074ec8057b8c6f7 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -453,14 +453,15 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 
                refcount_set(&dd->count, 1);
                list_add(&dd->list, &t->devices);
+               goto out;
 
        } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
                r = upgrade_mode(dd, mode, t->md);
                if (r)
                        return r;
-               refcount_inc(&dd->count);
        }
-
+       refcount_inc(&dd->count);
+out:
        *result = dd->dm_dev;
        return 0;
 }