diff options
Diffstat (limited to 'Documentation/filesystems/sysfs-tagging.txt')
| -rw-r--r-- | Documentation/filesystems/sysfs-tagging.txt | 42 |
1 files changed, 0 insertions, 42 deletions
diff --git a/Documentation/filesystems/sysfs-tagging.txt b/Documentation/filesystems/sysfs-tagging.txt deleted file mode 100644 index c7c8e6438958..000000000000 --- 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namespace - - initial_ns() which returns the initial namesapce -- call kobj_ns_exit() when an individual tag is no longer valid |