Merge branch 'unix-Show-number-of-scm-files-in-fdinfo'

Kirill Tkhai says:

====================
unix: Show number of scm files in fdinfo

v2: Pass correct argument to locked in patch [2/2].

Unix sockets like a block box. You never know what is pending there:
there may be a file descriptor holding a mount or a block device,
or there may be whole universes with namespaces, sockets with receive
queues full of sockets etc.

The patchset makes number of pending scm files be visible in fdinfo.
This may be useful to determine, that socket should be investigated
or which task should be killed to put a reference counter on a resourse.

$cat /proc/[pid]/fdinfo/[unix_sk_fd] | grep scm_fds
scm_fds: 1
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Signed-off-by: David S. Miller <davem@davemloft.net>