[PATCH] block: add GENHD_FL_UNPARTITIONABLE

[Tejun Heo <tj@kernel.org>]

There are cases where suppressing partition scan is useful - e.g. for
lo devices and pseudo SATA devices which advertise to be a disk but
get upset on partition scan (some port multiplier control devices show
such behavior).

This patch adds GENHD_FL_UNPARTITIONABLE which suppresses partition
scan regardless of the number of possible partitions.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
---
 include/linux/genhd.h |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 02fa469..a6f9329 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -128,6 +128,7 @@ struct hd_struct {
 #define GENHD_FL_EXT_DEVT			64 /* allow extended devt */
 #define GENHD_FL_NATIVE_CAPACITY		128
 #define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE	256
+#define GENHD_FL_UNPARTITIONABLE		512
 
 enum {
 	DISK_EVENT_MEDIA_CHANGE			= 1 << 0, /* media changed */
@@ -236,7 +237,8 @@ static inline int disk_max_parts(struct gendisk *disk)
 
 static inline bool disk_partitionable(struct gendisk *disk)
 {
-	return disk_max_parts(disk) > 1;
+	return disk_max_parts(disk) > 1 &&
+		!(disk->flags & GENHD_FL_UNPARTITIONABLE);
 }
 
 static inline dev_t disk_devt(struct gendisk *disk)