gfs2: fix freeze error handling

After commit b77b4a4 ("gfs2: Rework freeze / thaw logic"),
the freeze error handling is broken because gfs2_do_thaw()
overwrites the 'error' variable, causing incorrect processing
of the original freeze error.

Fix this by calling gfs2_do_thaw() when gfs2_lock_fs_check_clean()
fails but ignoring its return value to preserve the original
freeze error for proper reporting.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: b77b4a4 ("gfs2: Rework freeze / thaw logic")
Cc: stable@vger.kernel.org # v6.5+
Signed-off-by: Alexey Velichayshiy <a.velichayshiy@ispras.ru>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Author: Alexey Velichayshiy

fs/gfs2/super.c

@@ -749,9 +749,7 @@ static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who,
 			break;
 		}
 
-		error = gfs2_do_thaw(sdp, who, freeze_owner);
-		if (error)
-			goto out;
+		(void)gfs2_do_thaw(sdp, who, freeze_owner);
 
 		if (error == -EBUSY)
 			fs_err(sdp, "waiting for recovery before freeze\n");