Re: [PATCH -V14 0/11] Generic name to handle and open by handlesyscalls

[Miklos Szeredi]

On Wed, 7 Jul 2010, J. Bruce Fields wrote:
> On Wed, Jul 07, 2010 at 12:57:26PM +1000, Neil Brown wrote:
> > The trouble with /proc/mounts is that it is somewhat clumsy to parse
> > (remember to handle \0ctal escapes) and doesn't include major/minor number
> > which is the primary key for identifying filesystems in Linux
> > (see /sys/class/bdi/MAJOR:MINOR which is e.g. the best place to configure
> > read-ahead for a filesystem).
> > 
> > So /proc/mounts could work (and would probably be better than a new syscall)
> > but I would really rather see something sane in /sys for
> > inspecting/configuring filesystems (rather than each filesystem doing their
> > own independent thing in /sys/fs).
> 
> If you use sys or proc, is it possible to get the uuid from a file
> descriptor or pathname without races?

You can do stat/fstat to find out the device number (which is unique,
but not persistent) then look for the major:minor calculated from
st_dev in /proc/self/mountinfo.

Thanks,
Miklos
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