Commit 5988ce23 authored May 28, 2011 by Namhyung Kim Committed by Jens Axboe May 28, 2011

nbd: adjust 'max_part' according to part_shift



The 'max_part' parameter determines how many partitions are supported
on each nbd device. However the actual number can be changed to the
power of 2 minus 1 form during the module initialization as
alloc_disk() is called with (1 << part_shift) for some reason.

So adjust 'max_part' also at least for consistency with loop and brd.
It is exported via sysfs already, and a user should check this value
after module loading if [s]he wants to use that number correctly
(i.e. fdisk or something).

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Laurent Vivier <Laurent.Vivier@bull.net>
Cc: Paul Clements <Paul.Clements@steeleye.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

parent 3b271082

drivers/block/nbd.c

+12 −1

Original line number	Original line	Diff line number	Diff line
	@@ -754,9 +754,20 @@ static int __init nbd_init(void)
	return -ENOMEM;		return -ENOMEM;

	part_shift = 0;		part_shift = 0;
	if (max_part > 0)		if (max_part > 0) {
	part_shift = fls(max_part);		part_shift = fls(max_part);

			/*
			* Adjust max_part according to part_shift as it is exported
			* to user space so that user can know the max number of
			* partition kernel should be able to manage.
			*
			* Note that -1 is required because partition 0 is reserved
			* for the whole disk.
			*/
			max_part = (1UL << part_shift) - 1;
			}

	if ((1UL << part_shift) > DISK_MAX_PARTS)		if ((1UL << part_shift) > DISK_MAX_PARTS)
	return -EINVAL;		return -EINVAL;