bug#29038: df hangs on fifos/named pipes

[Stephane Chazelas]

2017-10-30 09:53:01 -0700, Pádraig Brady:
[...]
> I pushed my change with the comments fixed up.
> 
> I thought about O_NONBLOCK and O_PATH but thought these might not
> induce or wait for the auto mount to occur.
[...]

Note that:

df /dev/watchdog

as root still causes the system to reboot on Linux. Not a POSIX
conformance issue as the behaviour is unspecified for device
files without a mounted file system on, but still not ideal.

The point is that opening files has or can have side effects and
df is not *meant* to open files.

I would think that automounting directories assuming we do want
it to happen should be enough unless someone can come up with a
realistic use case where non-directory files are being
automounted (and assuming that's possible).

-- 
Stephane