b592fcfe7f
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/*. What I want is a separate /sys/class/net directory in sysfs for each network namespace, and I want to name each of them /sys/class/net. I looked and the VFS actually allows that. All that is needed is for /sys/class/net to implement a follow link method to redirect lookups to the real directory you want. Implementing a follow link method that is sensitive to the current network namespace turns out to be 3 lines of code so it looks like a clean approach. Modifying sysfs so it doesn't get in my was is a bit trickier. I am calling the concept of multiple directories all at the same path in the filesystem shadow directories. With the directory entry really at that location the shadow master. The following patch modifies sysfs so it can handle a directory structure slightly different from the kobject tree so I can implement the shadow directories for handling /sys/class/net/. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
230 lines
5.2 KiB
C
230 lines
5.2 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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*
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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/list.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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struct nameidata;
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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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};
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struct attribute_group {
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const char * name;
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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, .owner = THIS_MODULE }, \
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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, .owner = THIS_MODULE }, \
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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 *, char *, loff_t, size_t);
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ssize_t (*write)(struct kobject *, 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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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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atomic_t s_count;
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struct list_head s_sibling;
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struct list_head s_children;
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void * s_element;
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int s_type;
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umode_t s_mode;
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struct dentry * s_dentry;
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struct iattr * s_iattr;
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atomic_t s_event;
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};
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#define SYSFS_ROOT 0x0001
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#define SYSFS_DIR 0x0002
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#define SYSFS_KOBJ_ATTR 0x0004
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#define SYSFS_KOBJ_BIN_ATTR 0x0008
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#define SYSFS_KOBJ_LINK 0x0020
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#define SYSFS_NOT_PINNED (SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
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#ifdef CONFIG_SYSFS
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extern int __must_check
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sysfs_create_dir(struct kobject *, struct dentry *);
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extern void
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sysfs_remove_dir(struct kobject *);
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extern int __must_check
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sysfs_rename_dir(struct kobject *, struct dentry *, const char *new_name);
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extern int __must_check
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sysfs_move_dir(struct kobject *, struct kobject *);
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extern int __must_check
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sysfs_create_file(struct kobject *, const struct attribute *);
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extern int __must_check
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sysfs_update_file(struct kobject *, const struct attribute *);
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extern int __must_check
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sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode);
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extern void
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sysfs_remove_file(struct kobject *, const struct attribute *);
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extern int __must_check
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sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name);
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extern void
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sysfs_remove_link(struct kobject *, const char * name);
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int __must_check sysfs_create_bin_file(struct kobject *kobj,
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struct bin_attribute *attr);
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void sysfs_remove_bin_file(struct kobject *kobj, struct bin_attribute *attr);
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int __must_check sysfs_create_group(struct kobject *,
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const struct attribute_group *);
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void sysfs_remove_group(struct kobject *, const struct attribute_group *);
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void sysfs_notify(struct kobject * k, char *dir, char *attr);
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extern int sysfs_make_shadowed_dir(struct kobject *kobj,
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void * (*follow_link)(struct dentry *, struct nameidata *));
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extern struct dentry *sysfs_create_shadow_dir(struct kobject *kobj);
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extern void sysfs_remove_shadow_dir(struct dentry *dir);
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extern int __must_check sysfs_init(void);
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#else /* CONFIG_SYSFS */
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static inline int sysfs_create_dir(struct kobject * k, struct dentry *shadow)
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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 * k)
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{
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;
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}
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static inline int sysfs_rename_dir(struct kobject * k,
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struct dentry *new_parent,
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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 * k, struct kobject * new_parent)
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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 * k, const struct attribute * a)
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{
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return 0;
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}
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static inline int sysfs_update_file(struct kobject * k, const struct attribute * a)
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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, 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 * k, const struct attribute * a)
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{
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;
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}
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static inline int sysfs_create_link(struct kobject * k, struct kobject * t, const char * n)
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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 * k, const char * name)
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{
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;
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}
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static inline int sysfs_create_bin_file(struct kobject * k, struct bin_attribute * a)
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{
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return 0;
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}
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static inline int sysfs_remove_bin_file(struct kobject * k, struct bin_attribute * a)
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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 * k, const struct attribute_group *g)
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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 * k, const struct attribute_group * g)
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{
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;
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}
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static inline void sysfs_notify(struct kobject * k, char *dir, char *attr)
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{
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}
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static inline int sysfs_make_shadowed_dir(struct kobject *kobj,
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void * (*follow_link)(struct dentry *, struct nameidata *))
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{
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return 0;
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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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#endif /* CONFIG_SYSFS */
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#endif /* _SYSFS_H_ */
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