]> err.no Git - linux-2.6/commit
sysfs: add /sys/dev/{char,block} to lookup sysfs path by major:minor
authorDan Williams <dan.j.williams@intel.com>
Mon, 21 Apr 2008 17:51:07 +0000 (10:51 -0700)
committerGreg Kroah-Hartman <gregkh@suse.de>
Tue, 22 Jul 2008 04:54:40 +0000 (21:54 -0700)
commite105b8bfc769b0545b6f0f395179d1e43cbee822
tree23a1f0839547829c4ca6e89cd40adf285eb9feb6
parent93ded9b8fd42abe2c3607097963d8de6ad9117eb
sysfs: add /sys/dev/{char,block} to lookup sysfs path by major:minor

Why?:
There are occasions where userspace would like to access sysfs
attributes for a device but it may not know how sysfs has named the
device or the path.  For example what is the sysfs path for
/dev/disk/by-id/ata-ST3160827AS_5MT004CK?  With this change a call to
stat(2) returns the major:minor then userspace can see that
/sys/dev/block/8:32 links to /sys/block/sdc.

What are the alternatives?:
1/ Add an ioctl to return the path: Doable, but sysfs is meant to reduce
   the need to proliferate ioctl interfaces into the kernel, so this
   seems counter productive.

2/ Use udev to create these symlinks: Also doable, but it adds a
   udev dependency to utilities that might be running in a limited
   environment like an initramfs.

3/ Do a full-tree search of sysfs.

[kay.sievers@vrfy.org: fix duplicate registrations]
[kay.sievers@vrfy.org: cleanup suggestions]

Cc: Neil Brown <neilb@suse.de>
Cc: Tejun Heo <htejun@gmail.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Reviewed-by: SL Baur <steve@xemacs.org>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: Mark Lord <lkml@rtr.ca>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Documentation/ABI/testing/sysfs-dev [new file with mode: 0644]
Documentation/filesystems/sysfs.txt
block/genhd.c
drivers/base/class.c
drivers/base/core.c
drivers/usb/core/devio.c
include/linux/device.h