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>
89 lines
1.8 KiB
C
89 lines
1.8 KiB
C
/*
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* fs/sysfs/group.c - Operations for adding/removing multiple files at once.
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*
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* Copyright (c) 2003 Patrick Mochel
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* Copyright (c) 2003 Open Source Development Lab
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*
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* This file is released undert the GPL v2.
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*
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*/
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/dcache.h>
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#include <linux/namei.h>
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#include <linux/err.h>
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#include <linux/fs.h>
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#include <asm/semaphore.h>
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#include "sysfs.h"
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static void remove_files(struct dentry * dir,
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const struct attribute_group * grp)
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{
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struct attribute *const* attr;
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for (attr = grp->attrs; *attr; attr++)
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sysfs_hash_and_remove(dir,(*attr)->name);
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}
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static int create_files(struct dentry * dir,
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const struct attribute_group * grp)
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{
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struct attribute *const* attr;
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int error = 0;
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for (attr = grp->attrs; *attr && !error; attr++) {
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error = sysfs_add_file(dir, *attr, SYSFS_KOBJ_ATTR);
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}
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if (error)
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remove_files(dir,grp);
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return error;
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}
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int sysfs_create_group(struct kobject * kobj,
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const struct attribute_group * grp)
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{
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struct dentry * dir;
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int error;
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BUG_ON(!kobj || !kobj->dentry);
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if (grp->name) {
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error = sysfs_create_subdir(kobj,grp->name,&dir);
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if (error)
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return error;
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} else
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dir = kobj->dentry;
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dir = dget(dir);
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if ((error = create_files(dir,grp))) {
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if (grp->name)
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sysfs_remove_subdir(dir);
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}
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dput(dir);
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return error;
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}
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void sysfs_remove_group(struct kobject * kobj,
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const struct attribute_group * grp)
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{
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struct dentry * dir;
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if (grp->name)
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dir = lookup_one_len(grp->name, kobj->dentry,
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strlen(grp->name));
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else
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dir = dget(kobj->dentry);
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remove_files(dir,grp);
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if (grp->name)
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sysfs_remove_subdir(dir);
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/* release the ref. taken in this routine */
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dput(dir);
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}
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EXPORT_SYMBOL_GPL(sysfs_create_group);
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EXPORT_SYMBOL_GPL(sysfs_remove_group);
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