Commit d0985394 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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block: Revert "[SCSI] genhd: add a new attribute "alias" in gendisk" 

This reverts commit a72c5e5e.

The commit introduced alias for block devices which is intended to be
used during logging although actual usage hasn't been committed yet.
This approach adds very limited benefit (raw log might be easier to
follow) which can be trivially implemented in userland but has a lot
of problems.

It is much worse than netif renames because it doesn't rename the
actual device but just adds conveninence name which isn't used
universally or enforced.  Everything internal including device lookup
and sysfs still uses the internal name and nothing prevents two
devices from using conflicting alias - ie. sda can have sdb as its
alias.

This has been nacked by people working on device driver core, block
layer and kernel-userland interface and shouldn't have been
upstreamed.  Revert it.

 http://thread.gmane.org/gmane.linux.kernel/1155104
 http://thread.gmane.org/gmane.linux.scsi/68632
 http://thread.gmane.org/gmane.linux.scsi/69776



Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
 Acked-by: default avatarKay Sievers <kay.sievers@vrfy.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Nao Nishijima <nao.nishijima.xt@hitachi.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1ea6b8f4

Documentation/ABI/testing/sysfs-block

+0 −13
Original line number Diff line number Diff line
@@ -206,16 +206,3 @@ Description: 
		when a discarded area is read the discard_zeroes_data

		parameter will be set to one. Otherwise it will be 0 and

		the result of reading a discarded area is undefined.
 
What:		/sys/block/<disk>/alias

Date:		Aug 2011

Contact:	Nao Nishijima <nao.nishijima.xt@hitachi.com>

Description:

		A raw device name of a disk does not always point a same disk

		each boot-up time. Therefore, users have to use persistent

		device names, which udev creates when the kernel finds a disk,

		instead of raw device name. However, kernel doesn't show those

		persistent names on its messages (e.g. dmesg).

		This file can store an alias of the disk and it would be

		appeared in kernel messages if it is set. A disk can have an

		alias which length is up to 255bytes. Users can use alphabets,

		numbers, "-" and "_" in alias name. This file is writeonce.

block/genhd.c

+0 −71
Original line number Diff line number Diff line
@@ -19,7 +19,6 @@ 
#include <linux/mutex.h>

#include <linux/idr.h>

#include <linux/log2.h>

#include <linux/ctype.h>



#include "blk.h"
@@ -916,74 +915,6 @@ static int __init genhd_device_init(void) 


subsys_initcall(genhd_device_init);



static ssize_t alias_show(struct device *dev,

			       struct device_attribute *attr, char *buf)

{

	struct gendisk *disk = dev_to_disk(dev);

	ssize_t ret = 0;



	if (disk->alias)

		ret = snprintf(buf, ALIAS_LEN, "%s\n", disk->alias);

	return ret;

}



static ssize_t alias_store(struct device *dev, struct device_attribute *attr,

			   const char *buf, size_t count)

{

	struct gendisk *disk = dev_to_disk(dev);

	char *alias;

	char *envp[] = { NULL, NULL };

	unsigned char c;

	int i;

	ssize_t ret = count;



	if (!count)

		return -EINVAL;



	if (count >= ALIAS_LEN) {

		printk(KERN_ERR "alias: alias is too long\n");

		return -EINVAL;

	}



	/* Validation check */

	for (i = 0; i < count; i++) {

		c = buf[i];

		if (i == count - 1 && c == '\n')

			break;

		if (!isalnum(c) && c != '_' && c != '-') {

			printk(KERN_ERR "alias: invalid alias\n");

			return -EINVAL;

		}

	}



	if (disk->alias) {

		printk(KERN_INFO "alias: %s is already assigned (%s)\n",

		       disk->disk_name, disk->alias);

		return -EINVAL;

	}



	alias = kasprintf(GFP_KERNEL, "%s", buf);

	if (!alias)

		return -ENOMEM;



	if (alias[count - 1] == '\n')

		alias[count - 1] = '\0';



	envp[0] = kasprintf(GFP_KERNEL, "ALIAS=%s", alias);

	if (!envp[0]) {

		kfree(alias);

		return -ENOMEM;

	}



	disk->alias = alias;

	printk(KERN_INFO "alias: assigned %s to %s\n", alias, disk->disk_name);



	kobject_uevent_env(&dev->kobj, KOBJ_ADD, envp);



	kfree(envp[0]);

	return ret;

}



static ssize_t disk_range_show(struct device *dev,

			       struct device_attribute *attr, char *buf)

{
@@ -1043,7 +974,6 @@ static ssize_t disk_discard_alignment_show(struct device *dev, 
	return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));

}



static DEVICE_ATTR(alias, S_IRUGO|S_IWUSR, alias_show, alias_store);

static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);

static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);

static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
@@ -1066,7 +996,6 @@ static struct device_attribute dev_attr_fail_timeout = 
#endif



static struct attribute *disk_attrs[] = {

	&dev_attr_alias.attr,

	&dev_attr_range.attr,

	&dev_attr_ext_range.attr,

	&dev_attr_removable.attr,

include/linux/genhd.h

+0 −4
Original line number Diff line number Diff line
@@ -21,8 +21,6 @@ 
#define dev_to_part(device)	container_of((device), struct hd_struct, __dev)

#define disk_to_dev(disk)	(&(disk)->part0.__dev)

#define part_to_dev(part)	(&((part)->__dev))

#define alias_name(disk)	((disk)->alias ? (disk)->alias : \

						 (disk)->disk_name)



extern struct device_type part_type;

extern struct kobject *block_depr;
@@ -60,7 +58,6 @@ enum { 


#define DISK_MAX_PARTS			256

#define DISK_NAME_LEN			32

#define ALIAS_LEN			256



#include <linux/major.h>

#include <linux/device.h>
@@ -166,7 +163,6 @@ struct gendisk { 
                                         * disks that can't be partitioned. */



	char disk_name[DISK_NAME_LEN];	/* name of major driver */

	char *alias;			/* alias name of disk */

	char *(*devnode)(struct gendisk *gd, mode_t *mode);



	unsigned int events;		/* supported events */

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