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3ff195b011
The problem. When implementing a network namespace I need to be able to have multiple network devices with the same name. Currently this is a problem for /sys/class/net/*, /sys/devices/virtual/net/*, and potentially a few other directories of the form /sys/ ... /net/*. What this patch does is to add an additional tag field to the sysfs dirent structure. For directories that should show different contents depending on the context such as /sys/class/net/, and /sys/devices/virtual/net/ this tag field is used to specify the context in which those directories should be visible. Effectively this is the same as creating multiple distinct directories with the same name but internally to sysfs the result is nicer. I am calling the concept of a single directory that looks like multiple directories all at the same path in the filesystem tagged directories. For the networking namespace the set of directories whose contents I need to filter with tags can depend on the presence or absence of hotplug hardware or which modules are currently loaded. Which means I need a simple race free way to setup those directories as tagged. To achieve a reace free design all tagged directories are created and managed by sysfs itself. Users of this interface: - define a type in the sysfs_tag_type enumeration. - call sysfs_register_ns_types with the type and it's operations - sysfs_exit_ns when an individual tag is no longer valid - Implement mount_ns() which returns the ns of the calling process so we can attach it to a sysfs superblock. - Implement ktype.namespace() which returns the ns of a syfs kobject. Everything else is left up to sysfs and the driver layer. For the network namespace mount_ns and namespace() are essentially one line functions, and look to remain that. Tags are currently represented a const void * pointers as that is both generic, prevides enough information for equality comparisons, and is trivial to create for current users, as it is just the existing namespace pointer. The work needed in sysfs is more extensive. At each directory or symlink creating I need to check if the directory it is being created in is a tagged directory and if so generate the appropriate tag to place on the sysfs_dirent. Likewise at each symlink or directory removal I need to check if the sysfs directory it is being removed from is a tagged directory and if so figure out which tag goes along with the name I am deleting. Currently only directories which hold kobjects, and symlinks are supported. There is not enough information in the current file attribute interfaces to give us anything to discriminate on which makes it useless, and there are no potential users which makes it an uninteresting problem to solve. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Benjamin Thery <benjamin.thery@bull.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
338 lines
8.5 KiB
C
338 lines
8.5 KiB
C
/*
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* sysfs.h - definitions for the device driver filesystem
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*
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* Copyright (c) 2001,2002 Patrick Mochel
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* Copyright (c) 2004 Silicon Graphics, Inc.
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#ifndef _SYSFS_H_
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#define _SYSFS_H_
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/list.h>
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#include <linux/lockdep.h>
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#include <asm/atomic.h>
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struct kobject;
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struct module;
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enum kobj_ns_type;
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/* FIXME
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* The *owner field is no longer used.
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* x86 tree has been cleaned up. The owner
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* attribute is still left for other arches.
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*/
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struct attribute {
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const char *name;
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struct module *owner;
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mode_t mode;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lock_class_key *key;
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struct lock_class_key skey;
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#endif
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};
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/**
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* sysfs_attr_init - initialize a dynamically allocated sysfs attribute
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* @attr: struct attribute to initialize
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*
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* Initialize a dynamically allocated struct attribute so we can
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* make lockdep happy. This is a new requirement for attributes
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* and initially this is only needed when lockdep is enabled.
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* Lockdep gives a nice error when your attribute is added to
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* sysfs if you don't have this.
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*/
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define sysfs_attr_init(attr) \
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do { \
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static struct lock_class_key __key; \
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\
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(attr)->key = &__key; \
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} while(0)
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#else
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#define sysfs_attr_init(attr) do {} while(0)
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#endif
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struct attribute_group {
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const char *name;
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mode_t (*is_visible)(struct kobject *,
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struct attribute *, int);
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struct attribute **attrs;
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};
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/**
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* Use these macros to make defining attributes easier. See include/linux/device.h
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* for examples..
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*/
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#define __ATTR(_name,_mode,_show,_store) { \
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.attr = {.name = __stringify(_name), .mode = _mode }, \
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.show = _show, \
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.store = _store, \
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}
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#define __ATTR_RO(_name) { \
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.attr = { .name = __stringify(_name), .mode = 0444 }, \
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.show = _name##_show, \
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}
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#define __ATTR_NULL { .attr = { .name = NULL } }
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#define attr_name(_attr) (_attr).attr.name
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struct vm_area_struct;
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struct bin_attribute {
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struct attribute attr;
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size_t size;
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void *private;
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ssize_t (*read)(struct kobject *, struct bin_attribute *,
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char *, loff_t, size_t);
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ssize_t (*write)(struct kobject *, struct bin_attribute *,
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char *, loff_t, size_t);
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int (*mmap)(struct kobject *, struct bin_attribute *attr,
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struct vm_area_struct *vma);
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};
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/**
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* sysfs_bin_attr_init - initialize a dynamically allocated bin_attribute
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* @attr: struct bin_attribute to initialize
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*
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* Initialize a dynamically allocated struct bin_attribute so we
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* can make lockdep happy. This is a new requirement for
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* attributes and initially this is only needed when lockdep is
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* enabled. Lockdep gives a nice error when your attribute is
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* added to sysfs if you don't have this.
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*/
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#define sysfs_bin_attr_init(bin_attr) sysfs_attr_init(&(bin_attr)->attr)
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struct sysfs_ops {
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ssize_t (*show)(struct kobject *, struct attribute *,char *);
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ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t);
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};
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struct sysfs_dirent;
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#ifdef CONFIG_SYSFS
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int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
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void *data, struct module *owner);
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int __must_check sysfs_create_dir(struct kobject *kobj);
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void sysfs_remove_dir(struct kobject *kobj);
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int __must_check sysfs_rename_dir(struct kobject *kobj, const char *new_name);
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int __must_check sysfs_move_dir(struct kobject *kobj,
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struct kobject *new_parent_kobj);
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int __must_check sysfs_create_file(struct kobject *kobj,
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const struct attribute *attr);
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int __must_check sysfs_create_files(struct kobject *kobj,
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const struct attribute **attr);
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int __must_check sysfs_chmod_file(struct kobject *kobj, struct attribute *attr,
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mode_t mode);
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void sysfs_remove_file(struct kobject *kobj, const struct attribute *attr);
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void sysfs_remove_files(struct kobject *kobj, const struct attribute **attr);
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int __must_check sysfs_create_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr);
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void sysfs_remove_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr);
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int __must_check sysfs_create_link(struct kobject *kobj, struct kobject *target,
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const char *name);
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int __must_check sysfs_create_link_nowarn(struct kobject *kobj,
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struct kobject *target,
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const char *name);
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void sysfs_remove_link(struct kobject *kobj, const char *name);
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int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
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const char *old_name, const char *new_name);
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int __must_check sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp);
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int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_remove_group(struct kobject *kobj,
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const struct attribute_group *grp);
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int sysfs_add_file_to_group(struct kobject *kobj,
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const struct attribute *attr, const char *group);
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void sysfs_remove_file_from_group(struct kobject *kobj,
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const struct attribute *attr, const char *group);
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void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
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void sysfs_notify_dirent(struct sysfs_dirent *sd);
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struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
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const void *ns,
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const unsigned char *name);
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struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
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void sysfs_put(struct sysfs_dirent *sd);
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void sysfs_printk_last_file(void);
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void sysfs_exit_ns(enum kobj_ns_type type, const void *tag);
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int __must_check sysfs_init(void);
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#else /* CONFIG_SYSFS */
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static inline int sysfs_schedule_callback(struct kobject *kobj,
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void (*func)(void *), void *data, struct module *owner)
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{
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return -ENOSYS;
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}
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static inline int sysfs_create_dir(struct kobject *kobj)
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{
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return 0;
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}
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static inline void sysfs_remove_dir(struct kobject *kobj)
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{
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}
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static inline int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
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{
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return 0;
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}
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static inline int sysfs_move_dir(struct kobject *kobj,
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struct kobject *new_parent_kobj)
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{
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return 0;
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}
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static inline int sysfs_create_file(struct kobject *kobj,
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const struct attribute *attr)
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{
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return 0;
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}
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static inline int sysfs_create_files(struct kobject *kobj,
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const struct attribute **attr)
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{
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return 0;
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}
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static inline int sysfs_chmod_file(struct kobject *kobj,
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struct attribute *attr, mode_t mode)
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{
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return 0;
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}
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static inline void sysfs_remove_file(struct kobject *kobj,
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const struct attribute *attr)
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{
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}
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static inline void sysfs_remove_files(struct kobject *kobj,
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const struct attribute **attr)
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{
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}
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static inline int sysfs_create_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr)
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{
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return 0;
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}
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static inline void sysfs_remove_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr)
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{
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}
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static inline int sysfs_create_link(struct kobject *kobj,
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struct kobject *target, const char *name)
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{
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return 0;
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}
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static inline int sysfs_create_link_nowarn(struct kobject *kobj,
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struct kobject *target,
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const char *name)
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{
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return 0;
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}
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static inline void sysfs_remove_link(struct kobject *kobj, const char *name)
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{
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}
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static inline int sysfs_rename_link(struct kobject *k, struct kobject *t,
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const char *old_name, const char *new_name)
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{
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return 0;
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}
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static inline int sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline void sysfs_remove_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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}
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static inline int sysfs_add_file_to_group(struct kobject *kobj,
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const struct attribute *attr, const char *group)
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{
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return 0;
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}
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static inline void sysfs_remove_file_from_group(struct kobject *kobj,
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const struct attribute *attr, const char *group)
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{
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}
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static inline void sysfs_notify(struct kobject *kobj, const char *dir,
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const char *attr)
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{
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}
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static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
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{
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}
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static inline
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struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
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const void *ns,
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const unsigned char *name)
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{
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return NULL;
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}
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static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
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{
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return NULL;
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}
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static inline void sysfs_put(struct sysfs_dirent *sd)
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{
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}
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static inline void sysfs_exit_ns(enum kobj_ns_type type, const void *tag)
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{
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}
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static inline int __must_check sysfs_init(void)
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{
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return 0;
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}
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static inline void sysfs_printk_last_file(void)
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{
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}
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#endif /* CONFIG_SYSFS */
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#endif /* _SYSFS_H_ */
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