0006-block-add-no_part_scan-module-parameter.patch

From afe073973e6e402938790ca3b1b37d24422d36ba Mon Sep 17 00:00:00 2001
From: Rusty Bird <rustybird@openmailbox.org>
Date: Mon, 11 Jul 2016 13:05:38 +0000
Subject: [PATCH] block: add no_part_scan module parameter

Define a boolean module parameter named "no_part_scan" defaulting to N,
which, if set to Y, always causes the GENHD_FL_NO_PART_SCAN flag to be
added to subsequently created block devices, thereby disabling the
kernel's various partition table parsers for them.

The parameter's current value can be changed at any time by writing to
the /sys/module/block/parameters/no_part_scan file.
---
 block/genhd.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 06b642b23a07..15769cadd687 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -784,6 +784,15 @@ static void register_disk(struct device *parent, struct gendisk *disk,
 	return ret;
 }
 
+/* copied (not moved) from far down below, to have fewer patch hunks */
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX     "block."
+
+/* partition scanning policy */
+static bool disk_no_part_scan = 0;
+module_param_named(no_part_scan, disk_no_part_scan, bool, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(no_part_scan, "When adding block devices, always mark them as not to be scanned for partitions");
+
 /**
  * device_add_disk - add disk information to kernel list
  * @parent: parent device for the disk
@@ -812,6 +821,9 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
 	 */
 	elevator_init_mq(disk->queue);
 
+	if (disk_no_part_scan)
+		disk->flags |= GENHD_FL_NO_PART;
+
 	/* Mark bdev as having a submit_bio, if needed */
 	if (disk->fops->submit_bio)
 		bdev_set_flag(disk->part0, BD_HAS_SUBMIT_BIO);
-- 
2.25.4