fs: dlm: handle -EBUSY first in lock arg validation

commit 44637ca upstream.

During lock arg validation, first check for -EBUSY cases, then for
-EINVAL cases. The -EINVAL checks look at lkb state variables
which are not stable when an lkb is busy and would cause an
-EBUSY result, e.g. lkb->lkb_grmode.

Cc: stable@vger.kernel.org
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/dlm/lock.c

@@ -2864,17 +2864,9 @@ static int set_unlock_args(uint32_t flags, void *astarg, struct dlm_args *args)
 static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 			      struct dlm_args *args)
 {
-	int rv = -EINVAL;
+	int rv = -EBUSY;
 
 	if (args->flags & DLM_LKF_CONVERT) {
-		if (lkb->lkb_flags & DLM_IFL_MSTCPY)
-			goto out;
-
-		if (args->flags & DLM_LKF_QUECVT &&
-		    !__quecvt_compat_matrix[lkb->lkb_grmode+1][args->mode+1])
-			goto out;
-
-		rv = -EBUSY;
 		if (lkb->lkb_status != DLM_LKSTS_GRANTED)
 			goto out;
 
@@ -2884,6 +2876,14 @@ static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 
 		if (is_overlap(lkb))
 			goto out;
+
+		rv = -EINVAL;
+		if (lkb->lkb_flags & DLM_IFL_MSTCPY)
+			goto out;
+
+		if (args->flags & DLM_LKF_QUECVT &&
+		    !__quecvt_compat_matrix[lkb->lkb_grmode+1][args->mode+1])
+			goto out;
 	}
 
 	lkb->lkb_exflags = args->flags;