tag 15986 notabug thanks On 11/28/2013 03:34 PM, Philipp Thomas wrote: > Df in older coreutils showed the file of a loop mount whereas currently it > shows you the loop device. This is IMHO bogus as what good is that info? > > Is this a deliberate change or a side effect of other changes? I searched > ChangeLog but didn't find anything relating to it (at least in my eyes).
Hi Philipp, on systems where /etc/mtab is a regular file, 'mount' writes the name of the backing file into /etc/mtab. Nowadays, as /etc/mtab is a symlink to /proc/self/mounts, this information is not available to 'df' anymore. According to util-linux sources [1], such information is available in /sys/block/loopN/loop/backing_file (kernel >= 2.6.37 is required). Therefore, 'mount' makes this extra lookup in that file to display the name of the backing file. I don't think it's a good idea to add such functionality to 'df', as this is rather OS-dependent. Furthermore, OS-specific tools - in this case e.g. 'mount' from util-linux for the Linux platform - already display the name of the backing file. As it's therefore not a bug in 'df', I'm hereby marking this bug as done, but this should not prevent you or anybody else to continue discussion. [1] http://git.kernel.org/cgit/utils/util-linux/util-linux.git/tree/lib/loopdev.c#n518 Have a nice day, Berny
