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

		part_shift = 0;
		if (max_part > 0)
		if (max_part > 0) {
		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)
		return -EINVAL;

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