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

- 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>

diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst
index 7afb58dff43bd0c00600a316ffa27b74243812fe..14e298d84c8a6f4ac9614bb381fc281eea4502f6 100644 (file)
--- a/Documentation/filesystems/index.rst
+++ b/Documentation/filesystems/index.rst
@@ -35,6 +35,7 @@ algorithms work.
    seq_file
    sharedsubtree
    sysfs-pci
+   sysfs-tagging
 
    automount-support
 

diff --git a/Documentation/filesystems/sysfs-tagging.rst b/Documentation/filesystems/sysfs-tagging.rst
new file mode 100644 (file)
index 0000000..8888a05
--- /dev/null
+++ b/Documentation/filesystems/sysfs-tagging.rst
@@ -0,0 +1,48 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Sysfs tagging
+=============
+
+(Taken almost verbatim from Eric Biederman's netns tagging patch
+commit msg)
+
+The problem.  Network devices show up in sysfs and with the network
+namespace active multiple devices with the same name can show up in
+the same directory, ouch!
+
+To avoid that problem and allow existing applications in network
+namespaces to see the same interface that is currently presented in
+sysfs, sysfs now has tagging directory support.
+
+By using the network namespace pointers as tags to separate out the
+the sysfs directory entries we ensure that we don't have conflicts
+in the directories and applications only see a limited set of
+the network devices.
+
+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,
+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
+belongs.
+
+Each sysfs superblock's kernfs_super_info contains an array
+``void *ns[KOBJ_NS_TYPES]``.  When a task in a tagging namespace
+kobj_nstype first mounts sysfs, a new superblock is created.  It
+will be differentiated from other sysfs mounts by having its
+``s_fs_info->ns[kobj_nstype]`` set to the new namespace.  Note that
+through bind mounting and mounts propagation, a task can easily view
+the contents of other namespaces' sysfs mounts.  Therefore, when a
+namespace exits, it will call kobj_ns_exit() to invalidate any
+kernfs_node->ns pointers pointing to it.
+
+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
+
+  - current_ns() which returns current's namespace
+  - netlink_ns() which returns a socket's namespace
+  - initial_ns() which returns the initial namesapce
+
+- call kobj_ns_exit() when an individual tag is no longer valid

diff --git a/Documentation/filesystems/sysfs-tagging.txt b/Documentation/filesystems/sysfs-tagging.txt
deleted file mode 100644 (file)
index c7c8e64..0000000
--- a/Documentation/filesystems/sysfs-tagging.txt
+++ /dev/null
@@ -1,42 +0,0 @@
-Sysfs tagging
--------------
-
-(Taken almost verbatim from Eric Biederman's netns tagging patch
-commit msg)
-
-The problem.  Network devices show up in sysfs and with the network
-namespace active multiple devices with the same name can show up in
-the same directory, ouch!
-
-To avoid that problem and allow existing applications in network
-namespaces to see the same interface that is currently presented in
-sysfs, sysfs now has tagging directory support.
-
-By using the network namespace pointers as tags to separate out the
-the sysfs directory entries we ensure that we don't have conflicts
-in the directories and applications only see a limited set of
-the network devices.
-
-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,
-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
-belongs.
-
-Each sysfs superblock's kernfs_super_info contains an array void
-*ns[KOBJ_NS_TYPES].  When a task in a tagging namespace
-kobj_nstype first mounts sysfs, a new superblock is created.  It
-will be differentiated from other sysfs mounts by having its
-s_fs_info->ns[kobj_nstype] set to the new namespace.  Note that
-through bind mounting and mounts propagation, a task can easily view
-the contents of other namespaces' sysfs mounts.  Therefore, when a
-namespace exits, it will call kobj_ns_exit() to invalidate any
-kernfs_node->ns pointers pointing to it.
-
-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
-  - current_ns() which returns current's namespace
-  - netlink_ns() which returns a socket's namespace
-  - initial_ns() which returns the initial namesapce
-- call kobj_ns_exit() when an individual tag is no longer valid