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Commit e52eec13 authored by Andi Kleen's avatar Andi Kleen Committed by Greg Kroah-Hartman
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SYSFS: Allow boot time switching between deprecated and modern sysfs layout 



I have some systems which need legacy sysfs due to old tools that are
making assumptions that a directory can never be a symlink to another
directory, and it's a big hazzle to compile separate kernels for them.

This patch turns CONFIG_SYSFS_DEPRECATED into a run time option
that can be switched on/off the kernel command line. This way
the same binary can be used in both cases with just a option
on the command line.

The old CONFIG_SYSFS_DEPRECATED_V2 option is still there to set
the default. I kept the weird name to not break existing
config files.

Also the compat code can be still completely disabled by undefining
CONFIG_SYSFS_DEPRECATED_SWITCH -- just the optimizer takes
care of this now instead of lots of ifdefs. This makes the code
look nicer.

v2: This is an updated version on top of Kay's patch to only
handle the block devices. I tested it on my old systems
and that seems to work.

Cc: axboe@kernel.dk
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 39aba963

Documentation/kernel-parameters.txt

+9 −0
Original line number Diff line number Diff line
@@ -2365,6 +2365,15 @@ and is between 256 and 4096 characters. It is defined in the file 


	switches=	[HW,M68k]



	sysfs.deprecated=0|1 [KNL]

			Enable/disable old style sysfs layout for old udev

			on older distributions. When this option is enabled

			very new udev will not work anymore. When this option

			is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)

			in older udev will not work anymore.

			Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in

			the kernel configuration.



	sysrq_always_enabled

			[KNL]

			Ignore sysrq setting - this boot parameter will

block/genhd.c

+2 −5
Original line number Diff line number Diff line
@@ -22,9 +22,7 @@ 
#include "blk.h"



static DEFINE_MUTEX(block_class_lock);

#ifndef CONFIG_SYSFS_DEPRECATED

struct kobject *block_depr;

#endif



/* for extended dynamic devt allocation, currently only one major is used */

#define MAX_EXT_DEVT		(1 << MINORBITS)
@@ -803,10 +801,9 @@ static int __init genhd_device_init(void) 


	register_blkdev(BLOCK_EXT_MAJOR, "blkext");



#ifndef CONFIG_SYSFS_DEPRECATED

	/* create top-level block dir */

	if (!sysfs_deprecated)

		block_depr = kobject_create_and_add("block", NULL);

#endif

	return 0;

}

drivers/base/class.c

+2 −2
Original line number Diff line number Diff line
@@ -184,9 +184,9 @@ int __class_register(struct class *cls, struct lock_class_key *key) 
	if (!cls->dev_kobj)

		cls->dev_kobj = sysfs_dev_char_kobj;



#if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)

#if defined(CONFIG_BLOCK)

	/* let the block class directory show up in the root of sysfs */

	if (cls != &block_class)

	if (!sysfs_deprecated || cls != &block_class)

		cp->class_subsys.kobj.kset = class_kset;

#else

	cp->class_subsys.kobj.kset = class_kset;

drivers/base/core.c

+17 −9
Original line number Diff line number Diff line
@@ -26,6 +26,19 @@ 
#include "base.h"

#include "power/power.h"



#ifdef CONFIG_SYSFS_DEPRECATED

#ifdef CONFIG_SYSFS_DEPRECATED_V2

long sysfs_deprecated = 1;

#else

long sysfs_deprecated = 0;

#endif

static __init int sysfs_deprecated_setup(char *arg)

{

	return strict_strtol(arg, 10, &sysfs_deprecated);

}

early_param("sysfs.deprecated", sysfs_deprecated_setup);

#endif



int (*platform_notify)(struct device *dev) = NULL;

int (*platform_notify_remove)(struct device *dev) = NULL;

static struct kobject *dev_kobj;
@@ -617,14 +630,13 @@ static struct kobject *get_device_parent(struct device *dev, 
		struct kobject *parent_kobj;

		struct kobject *k;



#ifdef CONFIG_SYSFS_DEPRECATED

		/* block disks show up in /sys/block */

		if (dev->class == &block_class) {

		if (sysfs_deprecated && dev->class == &block_class) {

			if (parent && parent->class == &block_class)

				return &parent->kobj;

			return &block_class.p->class_subsys.kobj;

		}

#endif



		/*

		 * If we have no parent, we live in "virtual".

		 * Class-devices with a non class-device as parent, live
@@ -707,11 +719,9 @@ static int device_add_class_symlinks(struct device *dev) 
			goto out_subsys;

	}



#ifdef CONFIG_SYSFS_DEPRECATED

	/* /sys/block has directories and does not need symlinks */

	if (dev->class == &block_class)

	if (sysfs_deprecated && dev->class == &block_class)

		return 0;

#endif



	/* link in the class directory pointing to the device */

	error = sysfs_create_link(&dev->class->p->class_subsys.kobj,
@@ -738,10 +748,8 @@ static void device_remove_class_symlinks(struct device *dev) 
	if (dev->parent && device_is_not_partition(dev))

		sysfs_remove_link(&dev->kobj, "device");

	sysfs_remove_link(&dev->kobj, "subsystem");

#ifdef CONFIG_SYSFS_DEPRECATED

	if (dev->class == &block_class)

	if (sysfs_deprecated && dev->class == &block_class)

		return;

#endif

	sysfs_delete_link(&dev->class->p->class_subsys.kobj, &dev->kobj, dev_name(dev));

}

fs/partitions/check.c

+9 −10
Original line number Diff line number Diff line
@@ -513,14 +513,14 @@ void register_disk(struct gendisk *disk) 


	if (device_add(ddev))

		return;

#ifndef CONFIG_SYSFS_DEPRECATED

	if (!sysfs_deprecated) {

		err = sysfs_create_link(block_depr, &ddev->kobj,

					kobject_name(&ddev->kobj));

		if (err) {

			device_del(ddev);

			return;

		}

#endif

	}

	disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);

	disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
@@ -737,8 +737,7 @@ void del_gendisk(struct gendisk *disk) 
	kobject_put(disk->part0.holder_dir);

	kobject_put(disk->slave_dir);

	disk->driverfs_dev = NULL;

#ifndef CONFIG_SYSFS_DEPRECATED

	if (!sysfs_deprecated)

		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));

#endif

	device_del(disk_to_dev(disk));

}