Commit 727dc612 authored by Dan Ehrenberg's avatar Dan Ehrenberg Committed by Brian Norris
Browse files

mtd: part: Create the master device node when partitioned 



For many use cases, it helps to have a device node for the entire
MTD device as well as device nodes for the individual partitions.
For example, this allows querying the entire device's properties.
A common idiom is to create an additional partition which spans
over the whole device.

This patch makes a config option, CONFIG_MTD_PARTITIONED_MASTER,
which makes the master partition present even when the device is
partitioned. This isn't turned on by default since it presents
a backwards-incompatible device numbering.

The patch also makes the parent of a partition device be the master,
if the config flag is set, now that the master is a full device.

Signed-off-by: default avatarDan Ehrenberg <dehrenberg@chromium.org>
Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
parent 9cd5196e

drivers/mtd/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -309,6 +309,19 @@ config MTD_SWAP 
	  The driver provides wear leveling by storing erase counter into the

	  OOB.



config MTD_PARTITIONED_MASTER

	bool "Retain master device when partitioned"

	default n

	depends on MTD

	help

	  For historical reasons, by default, either a master is present or

	  several partitions are present, but not both. The concern was that

	  data listed in multiple partitions was dangerous; however, SCSI does

	  this and it is frequently useful for applications. This config option

	  leaves the master in even if the device is partitioned. It also makes

	  the parent of the partition device be the master device, rather than

	  what lies behind the master.



source "drivers/mtd/chips/Kconfig"



source "drivers/mtd/maps/Kconfig"

drivers/mtd/mtdcore.c

+36 −16
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
#include <linux/gfp.h>

#include <linux/slab.h>

#include <linux/reboot.h>

#include <linux/kconfig.h>



#include <linux/mtd/mtd.h>

#include <linux/mtd/partitions.h>
@@ -501,6 +502,29 @@ out_error: 
	return ret;

}



static int mtd_add_device_partitions(struct mtd_info *mtd,

				     struct mtd_partition *real_parts,

				     int nbparts)

{

	int ret;



	if (nbparts == 0 || IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) {

		ret = add_mtd_device(mtd);

		if (ret == 1)

			return -ENODEV;

	}



	if (nbparts > 0) {

		ret = add_mtd_partitions(mtd, real_parts, nbparts);

		if (ret && IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))

			del_mtd_device(mtd);

		return ret;

	}



	return 0;

}





/**

 * mtd_device_parse_register - parse partitions and register an MTD device.

 *
@@ -523,7 +547,8 @@ out_error: 
 *   found this functions tries to fallback to information specified in

 *   @parts/@nr_parts.

 * * If any partitioning info was found, this function registers the found

 *   partitions.

 *   partitions. If the MTD_PARTITIONED_MASTER option is set, then the device

 *   as a whole is registered first.

 * * If no partitions were found this function just registers the MTD device

 *   @mtd and exits.

 *
@@ -534,27 +559,21 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types, 
			      const struct mtd_partition *parts,

			      int nr_parts)

{

	int err;

	struct mtd_partition *real_parts;

	int ret;

	struct mtd_partition *real_parts = NULL;



	err = parse_mtd_partitions(mtd, types, &real_parts, parser_data);

	if (err <= 0 && nr_parts && parts) {

	ret = parse_mtd_partitions(mtd, types, &real_parts, parser_data);

	if (ret <= 0 && nr_parts && parts) {

		real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,

				     GFP_KERNEL);

		if (!real_parts)

			err = -ENOMEM;

			ret = -ENOMEM;

		else

			err = nr_parts;

			ret = nr_parts;

	}



	if (err > 0) {

		err = add_mtd_partitions(mtd, real_parts, err);

		kfree(real_parts);

	} else if (err == 0) {

		err = add_mtd_device(mtd);

		if (err == 1)

			err = -ENODEV;

	}

	if (ret >= 0)

		ret = mtd_add_device_partitions(mtd, real_parts, ret);



	/*

	 * FIXME: some drivers unfortunately call this function more than once.
@@ -569,7 +588,8 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types, 
		register_reboot_notifier(&mtd->reboot_notifier);

	}



	return err;

	kfree(real_parts);

	return ret;

}

EXPORT_SYMBOL_GPL(mtd_device_parse_register);

drivers/mtd/mtdpart.c

+13 −5
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <linux/mtd/mtd.h>

#include <linux/mtd/partitions.h>

#include <linux/err.h>

#include <linux/kconfig.h>



#include "mtdcore.h"
@@ -379,10 +380,17 @@ static struct mtd_part *allocate_partition(struct mtd_info *master, 
	slave->mtd.name = name;

	slave->mtd.owner = master->owner;



	/* NOTE:  we don't arrange MTDs as a tree; it'd be error-prone

	 * to have the same data be in two different partitions.

	/* NOTE: Historically, we didn't arrange MTDs as a tree out of

	 * concern for showing the same data in multiple partitions.

	 * However, it is very useful to have the master node present,

	 * so the MTD_PARTITIONED_MASTER option allows that. The master

	 * will have device nodes etc only if this is set, so make the

	 * parent conditional on that option. Note, this is a way to

	 * distinguish between the master and the partition in sysfs.

	 */

	slave->mtd.dev.parent = master->dev.parent;

	slave->mtd.dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) ?

				&master->dev :

				master->dev.parent;



	slave->mtd._read = part_read;

	slave->mtd._write = part_write;
@@ -631,8 +639,8 @@ EXPORT_SYMBOL_GPL(mtd_del_partition); 
 * and registers slave MTD objects which are bound to the master according to

 * the partition definitions.

 *

 * We don't register the master, or expect the caller to have done so,

 * for reasons of data integrity.

 * For historical reasons, this function's caller only registers the master

 * if the MTD_PARTITIONED_MASTER config option is set.

 */



int add_mtd_partitions(struct mtd_info *master,

CRA Git | Maintained and supported by SUSTech CRA and CCSE