From e105b8bfc769b0545b6f0f395179d1e43cbee822 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 21 Apr 2008 10:51:07 -0700 Subject: 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 Cc: Tejun Heo Acked-by: Kay Sievers Reviewed-by: SL Baur Acked-by: Kay Sievers Acked-by: Mark Lord Acked-by: H. Peter Anvin Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- block/genhd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 9074f384b097..24e3fc9095fe 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -370,7 +370,10 @@ static struct kobject *base_probe(dev_t devt, int *part, void *data) static int __init genhd_device_init(void) { - int error = class_register(&block_class); + int error; + + block_class.dev_kobj = sysfs_dev_block_kobj; + error = class_register(&block_class); if (unlikely(error)) return error; bdev_map = kobj_map_init(base_probe, &block_class_lock); -- cgit v1.2.2