Commit 5e71b7a6 authored by Olof Johansson's avatar Olof Johansson Committed by Chris Ball
Browse files

mmc: make number of mmcblk minors configurable 



The old limit of number of minor numbers per mmcblk device was hardcoded
at 8.  This isn't enough for some of the more elaborate partitioning
schemes, for example those used by Chrome OS.

Since there might be a bunch of systems out there with static /dev
contents that relies on the old numbering scheme, let's make it a
build-time option with the default set to the previous 8.

Also provide a boot/modprobe-time parameter to override the config
default: mmcblk.perdev_minors.

Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
Cc: Mandeep Baines <msb@chromium.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent 061c6c84

Documentation/devices.txt

+6 −0
Original line number Diff line number Diff line
@@ -2520,6 +2520,12 @@ Your cooperation is appreciated. 
		  8 = /dev/mmcblk1      Second SD/MMC card

		    ...



		The start of next SD/MMC card can be configured with

		CONFIG_MMC_BLOCK_MINORS, or overridden at boot/modprobe

		time using the mmcblk.perdev_minors option. That would

		bump the offset between each card to be the configured

		value instead of the default 8.



179 char	CCube DVXChip-based PCI products

		  0 = /dev/dvxirq0	First DVX device

		  1 = /dev/dvxirq1	Second DVX device

drivers/mmc/card/Kconfig

+17 −0
Original line number Diff line number Diff line
@@ -14,6 +14,23 @@ config MMC_BLOCK 
	  mount the filesystem. Almost everyone wishing MMC support

	  should say Y or M here.



config MMC_BLOCK_MINORS

	int "Number of minors per block device"

	range 4 256

	default 8

	help

	  Number of minors per block device. One is needed for every

	  partition on the disk (plus one for the whole disk).



	  Number of total MMC minors available is 256, so your number

	  of supported block devices will be limited to 256 divided

	  by this number.



	  Default is 8 to be backwards compatible with previous

	  hardwired device numbering.



	  If unsure, say 8 here.



config MMC_BLOCK_BOUNCE

	bool "Use bounce buffer for simple hosts"

	depends on MMC_BLOCK

drivers/mmc/card/block.c

+31 −12
Original line number Diff line number Diff line
@@ -43,15 +43,27 @@ 
#include "queue.h"



MODULE_ALIAS("mmc:block");

#ifdef MODULE_PARAM_PREFIX

#undef MODULE_PARAM_PREFIX

#endif

#define MODULE_PARAM_PREFIX "mmcblk."



static DEFINE_MUTEX(block_mutex);



/*

 * max 8 partitions per card

 * The defaults come from config options but can be overriden by module

 * or bootarg options.

 */

#define MMC_SHIFT	3

#define MMC_NUM_MINORS	(256 >> MMC_SHIFT)

static int perdev_minors = CONFIG_MMC_BLOCK_MINORS;



static DEFINE_MUTEX(block_mutex);

static DECLARE_BITMAP(dev_use, MMC_NUM_MINORS);

/*

 * We've only got one major, so number of mmcblk devices is

 * limited to 256 / number of minors per device.

 */

static int max_devices;



/* 256 minors, so at most 256 separate devices */

static DECLARE_BITMAP(dev_use, 256);



/*

 * There is one mmc_blk_data per slot.
@@ -67,6 +79,9 @@ struct mmc_blk_data { 


static DEFINE_MUTEX(open_lock);



module_param(perdev_minors, int, 0444);

MODULE_PARM_DESC(perdev_minors, "Minors numbers to allocate per device");



static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)

{

	struct mmc_blk_data *md;
@@ -88,10 +103,10 @@ static void mmc_blk_put(struct mmc_blk_data *md) 
	md->usage--;

	if (md->usage == 0) {

		int devmaj = MAJOR(disk_devt(md->disk));

		int devidx = MINOR(disk_devt(md->disk)) >> MMC_SHIFT;

		int devidx = MINOR(disk_devt(md->disk)) / perdev_minors;



		if (!devmaj)

			devidx = md->disk->first_minor >> MMC_SHIFT;

			devidx = md->disk->first_minor / perdev_minors;



		blk_cleanup_queue(md->queue.queue);
@@ -566,8 +581,8 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card) 
	struct mmc_blk_data *md;

	int devidx, ret;



	devidx = find_first_zero_bit(dev_use, MMC_NUM_MINORS);

	if (devidx >= MMC_NUM_MINORS)

	devidx = find_first_zero_bit(dev_use, max_devices);

	if (devidx >= max_devices)

		return ERR_PTR(-ENOSPC);

	__set_bit(devidx, dev_use);
@@ -584,7 +599,7 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card) 
	 */

	md->read_only = mmc_blk_readonly(card);



	md->disk = alloc_disk(1 << MMC_SHIFT);

	md->disk = alloc_disk(perdev_minors);

	if (md->disk == NULL) {

		ret = -ENOMEM;

		goto err_kfree;
@@ -601,7 +616,7 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card) 
	md->queue.data = md;



	md->disk->major	= MMC_BLOCK_MAJOR;

	md->disk->first_minor = devidx << MMC_SHIFT;

	md->disk->first_minor = devidx * perdev_minors;

	md->disk->fops = &mmc_bdops;

	md->disk->private_data = md;

	md->disk->queue = md->queue.queue;
@@ -670,7 +685,6 @@ static int mmc_blk_probe(struct mmc_card *card) 
{

	struct mmc_blk_data *md;

	int err;



	char cap_str[10];



	/*
@@ -760,6 +774,11 @@ static int __init mmc_blk_init(void) 
{

	int res;



	if (perdev_minors != CONFIG_MMC_BLOCK_MINORS)

		pr_info("mmcblk: using %d minors per device\n", perdev_minors);



	max_devices = 256 / perdev_minors;



	res = register_blkdev(MMC_BLOCK_MAJOR, "mmc");

	if (res)

		goto out;

CRA Git | Maintained and supported by SUSTech CRA and CCSE