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

From 56ce69a0260413418c2845182aa93165c4a1ce42 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 26b31fcae217..75993c12e123 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -676,6 +676,15 @@ static void register_disk(struct device *parent, struct gendisk *disk,
 	}
 }
 
+/* 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
@@ -704,6 +713,9 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
 	if (register_queue)
 		elevator_init_mq(disk->queue);
 
+	if (disk_no_part_scan)
+		disk->flags |= GENHD_FL_NO_PART_SCAN;
+
 	/* minors == 0 indicates to use ext devt from part0 and should
 	 * be accompanied with EXT_DEVT flag.  Make sure all
 	 * parameters make sense.
-- 
2.21.0