project-edgeos/sys-kernel/lakitu-kernel-5_15/files/0001-FEATURE-PATCH-dm-verity-dev-wait.patch

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 426299ceb33d..0fa4f55728df 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -16,6 +16,7 @@
 #include "dm-verity.h"
 #include "dm-verity-fec.h"
 #include "dm-verity-verify-sig.h"
+#include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/reboot.h>
 
@@ -48,6 +49,11 @@ struct dm_verity_prefetch_work {
 	unsigned n_blocks;
 };
 
+/* Controls whether verity_get_device will wait forever for a device. */
+static int dev_wait;
+module_param(dev_wait, int, 0444);
+MODULE_PARM_DESC(dev_wait, "Wait forever for a backing device");
+
 /*
  * Auxiliary structure appended to each dm-bufio buffer. If the value
  * hash_verified is nonzero, hash of the block has been verified.
@@ -1034,6 +1040,26 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
 	return r;
 }
 
+static int verity_get_device(struct dm_target *ti, const char *devname,
+			     struct dm_dev **dm_dev)
+{
+	do {
+		/* Try the normal path first since if everything is ready, it
+		 * will be the fastest.
+		 */
+		if (!dm_get_device(ti, devname,
+				   dm_table_get_mode(ti->table), dm_dev))
+			return 0;
+
+		if (!dev_wait)
+			break;
+
+		/* No need to be too aggressive since this is a slow path. */
+		msleep(500);
+	} while (dev_wait && (driver_probe_done() != 0 || *dm_dev == NULL));
+	return -1;
+}
+
 /*
  * Target parameters:
  *	<version>	The current format is version 1.
@@ -1093,13 +1119,13 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	}
 	v->version = num;
 
-	r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
+	r = verity_get_device(ti, argv[1], &v->data_dev);
 	if (r) {
 		ti->error = "Data device lookup failed";
 		goto bad;
 	}
 
-	r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
+	r = verity_get_device(ti, argv[2], &v->hash_dev);
 	if (r) {
 		ti->error = "Hash device lookup failed";
 		goto bad;