[PATCH] dm-verity: avoid double increment of &use_bh_wq_enabled

verity_parse_opt_args is called twice, first with the only_modifier_opts,
first with only_modifier_opts == true and then with only_modifier_opts ==
false. Thus, the static branch &use_bh_wq_enabled was incremented twice
and the destructor verity_dtr would only decrement it once.

Fix tihs bug by only incrementing it on the first call, on the second
call, when v->use_bh_wq is true, do nothing.

Signed-off-by: Mikulas Patocka <[email protected]>
Assisted-by: Claude:claude-opus-4-6
Cc: [email protected]
Fixes: df326e7a0699 ("dm verity: allow optional args to alter primary args handling")

---
 drivers/md/dm-verity-target.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6/drivers/md/dm-verity-target.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-verity-target.c	2026-07-01 13:24:34.000000000 +0200
+++ linux-2.6/drivers/md/dm-verity-target.c	2026-07-01 13:31:00.000000000 +0200
@@ -1262,6 +1262,8 @@ static int verity_parse_opt_args(struct
 			continue;
 
 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
+			if (v->use_bh_wq)
+				continue;
 			v->use_bh_wq = true;
 			static_branch_inc(&use_bh_wq_enabled);
 			continue;