On Mon, 20 Sep 2021 07:43:52 +0100 Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > On Sat, Sep 18, 2021 at 09:07:54AM +0200, Greg KH wrote: > > > Honestly, I wasn't particularly enthusiastic about it in the first > > > place; it feels like something that should be done in user space. > > > I wouldn't have included it if I didn't have to make a writable > > > copy of the buffer anyway, in order to trim a trailing newline. > > > > > > I can certainly remove the re-check logic. The end result will > > > be an API that is slightly less "user friendly" in return for > > > saving a bit of pointer arithmetic and a 5-byte memcpy(). > > > > Just use the kernel block device name and that way you do not have > > to parse anything as it is unique and no paths are having to be > > followed. > > > > That's the way that other LED apis are working, right? > > The "kernel block device name" is the a block device special path > that a normal VFS path lookup is done on. This is the preferred block > device API used by everyone. And yes, this includes resolving > symlinks. The only other API is by dev_t, but it is highly > discouraged and should really not grow any new users. Christoph, /sys/class/block lists block devices' kernel object names. I don't understand why can't blk API provide a function returns a block device given such name as seen in /sys/class/block directory. Can you elaborate on this? It seems really strange to me to not be able to do cd /sys/class/leds/<LED> echo blkdev >trigger echo sda1 >block_device and instead having to do (as the last command) echo /dev/sda1 >block_device And whas should we show when /dev/sda1 is paried to the trigger, and userspace reads the block_device sysfs file? Should we show the full path which was given when pairing, even if it may not be valid anymore? (Such as when the device file is removed from /dev.) Marek
