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docs: filesystems: convert sysfs-tagging.txt to ReST

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- Add a SPDX header;
- Adjust document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/45a01fa5edd5c6ee8fc0754fc74f7ef65a3e5581.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2020-04-27 23:17:18 +02:00 committed by Jonathan Corbet
parent 28bcadf0ae
commit ec4551f450
2 changed files with 15 additions and 8 deletions
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1
Documentation/filesystems/index.rst
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@ -35,6 +35,7 @@ algorithms work.
seq_file seq_file
sharedsubtree sharedsubtree
sysfs-pci sysfs-pci
sysfs-tagging
automount-support automount-support

22
Documentation/filesystems/sysfs-tagging.txt → Documentation/filesystems/sysfs-tagging.rst
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@ -1,5 +1,8 @@
.. SPDX-License-Identifier: GPL-2.0
=============
Sysfs tagging Sysfs tagging
------------- =============
(Taken almost verbatim from Eric Biederman's netns tagging patch (Taken almost verbatim from Eric Biederman's netns tagging patch
commit msg) commit msg)
@ -18,25 +21,28 @@ in the directories and applications only see a limited set of
the network devices. the network devices.
Each sysfs directory entry may be tagged with a namespace via the Each sysfs directory entry may be tagged with a namespace via the
void *ns member of its kernfs_node. If a directory entry is tagged, ``void *ns member`` of its ``kernfs_node``. If a directory entry is tagged,
then kernfs_node->flags will have a flag between KOBJ_NS_TYPE_NONE then ``kernfs_node->flags`` will have a flag between KOBJ_NS_TYPE_NONE
and KOBJ_NS_TYPES, and ns will point to the namespace to which it and KOBJ_NS_TYPES, and ns will point to the namespace to which it
belongs. belongs.
Each sysfs superblock's kernfs_super_info contains an array void Each sysfs superblock's kernfs_super_info contains an array
*ns[KOBJ_NS_TYPES]. When a task in a tagging namespace ``void *ns[KOBJ_NS_TYPES]``. When a task in a tagging namespace
kobj_nstype first mounts sysfs, a new superblock is created. It kobj_nstype first mounts sysfs, a new superblock is created. It
will be differentiated from other sysfs mounts by having its will be differentiated from other sysfs mounts by having its
s_fs_info->ns[kobj_nstype] set to the new namespace. Note that ``s_fs_info->ns[kobj_nstype]`` set to the new namespace. Note that
through bind mounting and mounts propagation, a task can easily view through bind mounting and mounts propagation, a task can easily view
the contents of other namespaces' sysfs mounts. Therefore, when a the contents of other namespaces' sysfs mounts. Therefore, when a
namespace exits, it will call kobj_ns_exit() to invalidate any namespace exits, it will call kobj_ns_exit() to invalidate any
kernfs_node->ns pointers pointing to it. kernfs_node->ns pointers pointing to it.
Users of this interface: Users of this interface:
- define a type in the kobj_ns_type enumeration.
- call kobj_ns_type_register() with its kobj_ns_type_operations which has - define a type in the ``kobj_ns_type`` enumeration.
- call kobj_ns_type_register() with its ``kobj_ns_type_operations`` which has
- current_ns() which returns current's namespace - current_ns() which returns current's namespace
- netlink_ns() which returns a socket's namespace - netlink_ns() which returns a socket's namespace
- initial_ns() which returns the initial namesapce - initial_ns() which returns the initial namesapce
- call kobj_ns_exit() when an individual tag is no longer valid - call kobj_ns_exit() when an individual tag is no longer valid