Commit 565dbe72 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet

docs: fs: proc.rst: convert a new chapter to ReST

A new chapter was added to proc.rst. Adjust the markups
to avoid this warning:

	Documentation/filesystems/proc.rst:2194: WARNING: Inconsistent literal block quoting.

And to properly mark the code-blocks there.

Fixes: 37e7647a ("docs: proc: add documentation for "hidepid=4" and "subset=pid" options and new mount behavior")
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/de67ec04a2e735f4450eb3ce966f7d80b9438244.1592895969.git.mchehab+huawei@kernel.orgSigned-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 985098a0
......@@ -2179,46 +2179,44 @@ subset=pid hides all top level files and directories in the procfs that
are not related to tasks.
5 Filesystem behavior
----------------------------
---------------------------
Originally, before the advent of pid namepsace, procfs was a global file
system. It means that there was only one procfs instance in the system.
When pid namespace was added, a separate procfs instance was mounted in
each pid namespace. So, procfs mount options are global among all
mountpoints within the same namespace.
::
mountpoints within the same namespace::
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=2 0 0
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=2 0 0
# strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
+++ exited with 0 +++
# strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
+++ exited with 0 +++
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=2 0 0
proc /tmp/proc proc rw,relatime,hidepid=2 0 0
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=2 0 0
proc /tmp/proc proc rw,relatime,hidepid=2 0 0
and only after remounting procfs mount options will change at all
mountpoints.
mountpoints::
# mount -o remount,hidepid=1 -t proc proc /tmp/proc
# mount -o remount,hidepid=1 -t proc proc /tmp/proc
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=1 0 0
proc /tmp/proc proc rw,relatime,hidepid=1 0 0
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=1 0 0
proc /tmp/proc proc rw,relatime,hidepid=1 0 0
This behavior is different from the behavior of other filesystems.
The new procfs behavior is more like other filesystems. Each procfs mount
creates a new procfs instance. Mount options affect own procfs instance.
It means that it became possible to have several procfs instances
displaying tasks with different filtering options in one pid namespace.
displaying tasks with different filtering options in one pid namespace::
# mount -o hidepid=invisible -t proc proc /proc
# mount -o hidepid=noaccess -t proc proc /tmp/proc
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=invisible 0 0
proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0
# mount -o hidepid=invisible -t proc proc /proc
# mount -o hidepid=noaccess -t proc proc /tmp/proc
# grep ^proc /proc/mounts
proc /proc proc rw,relatime,hidepid=invisible 0 0
proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0
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