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![Al Viro](/assets/img/avatar_default.png)
* new refcount in struct net, controlling actual freeing of the memory * new method in kobj_ns_type_operations (->drop_ns()) * ->current_ns() semantics change - it's supposed to be followed by corresponding ->drop_ns(). For struct net in case of CONFIG_NET_NS it bumps the new refcount; net_drop_ns() decrements it and calls net_free() if the last reference has been dropped. Method renamed to ->grab_current_ns(). * old net_free() callers call net_drop_ns() instead. * sysfs_exit_ns() is gone, along with a large part of callchain leading to it; now that the references stored in ->ns[...] stay valid we do not need to hunt them down and replace them with NULL. That fixes problems in sysfs_lookup() and sysfs_readdir(), along with getting rid of sb->s_instances abuse. Note that struct net *shutdown* logics has not changed - net_cleanup() is called exactly when it used to be called. The only thing postponed by having a sysfs instance refering to that struct net is actual freeing of memory occupied by struct net. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
201 lines
4.5 KiB
C
201 lines
4.5 KiB
C
/*
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* fs/sysfs/symlink.c - operations for initializing and mounting sysfs
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*
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* Copyright (c) 2001-3 Patrick Mochel
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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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* This file is released under the GPLv2.
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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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#define DEBUG
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include "sysfs.h"
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static struct vfsmount *sysfs_mnt;
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struct kmem_cache *sysfs_dir_cachep;
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static const struct super_operations sysfs_ops = {
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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.evict_inode = sysfs_evict_inode,
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};
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struct sysfs_dirent sysfs_root = {
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.s_name = "",
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.s_count = ATOMIC_INIT(1),
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.s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
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.s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
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.s_ino = 1,
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};
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static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct inode *inode;
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struct dentry *root;
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = SYSFS_MAGIC;
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sb->s_op = &sysfs_ops;
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sb->s_time_gran = 1;
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/* get root inode, initialize and unlock it */
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mutex_lock(&sysfs_mutex);
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inode = sysfs_get_inode(sb, &sysfs_root);
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mutex_unlock(&sysfs_mutex);
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if (!inode) {
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pr_debug("sysfs: could not get root inode\n");
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return -ENOMEM;
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}
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/* instantiate and link root dentry */
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root = d_alloc_root(inode);
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if (!root) {
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pr_debug("%s: could not get root dentry!\n",__func__);
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iput(inode);
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return -ENOMEM;
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}
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root->d_fsdata = &sysfs_root;
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sb->s_root = root;
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return 0;
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}
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static int sysfs_test_super(struct super_block *sb, void *data)
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{
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struct sysfs_super_info *sb_info = sysfs_info(sb);
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struct sysfs_super_info *info = data;
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enum kobj_ns_type type;
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int found = 1;
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for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
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if (sb_info->ns[type] != info->ns[type])
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found = 0;
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}
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return found;
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}
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static int sysfs_set_super(struct super_block *sb, void *data)
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{
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int error;
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error = set_anon_super(sb, data);
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if (!error)
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sb->s_fs_info = data;
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return error;
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}
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static void free_sysfs_super_info(struct sysfs_super_info *info)
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{
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int type;
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for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
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kobj_ns_drop(type, info->ns[type]);
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kfree(info);
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}
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static struct dentry *sysfs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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struct sysfs_super_info *info;
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enum kobj_ns_type type;
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struct super_block *sb;
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int error;
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info = kzalloc(sizeof(*info), GFP_KERNEL);
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if (!info)
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return ERR_PTR(-ENOMEM);
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for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
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info->ns[type] = kobj_ns_grab_current(type);
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sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
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if (IS_ERR(sb) || sb->s_fs_info != info)
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free_sysfs_super_info(info);
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if (IS_ERR(sb))
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return ERR_CAST(sb);
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if (!sb->s_root) {
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sb->s_flags = flags;
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error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
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if (error) {
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deactivate_locked_super(sb);
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return ERR_PTR(error);
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}
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sb->s_flags |= MS_ACTIVE;
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}
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return dget(sb->s_root);
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}
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static void sysfs_kill_sb(struct super_block *sb)
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{
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struct sysfs_super_info *info = sysfs_info(sb);
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/* Remove the superblock from fs_supers/s_instances
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* so we can't find it, before freeing sysfs_super_info.
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*/
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kill_anon_super(sb);
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free_sysfs_super_info(info);
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}
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static struct file_system_type sysfs_fs_type = {
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.name = "sysfs",
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.mount = sysfs_mount,
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.kill_sb = sysfs_kill_sb,
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};
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int __init sysfs_init(void)
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{
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int err = -ENOMEM;
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sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
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sizeof(struct sysfs_dirent),
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0, 0, NULL);
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if (!sysfs_dir_cachep)
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goto out;
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err = sysfs_inode_init();
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if (err)
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goto out_err;
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err = register_filesystem(&sysfs_fs_type);
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if (!err) {
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sysfs_mnt = kern_mount(&sysfs_fs_type);
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if (IS_ERR(sysfs_mnt)) {
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printk(KERN_ERR "sysfs: could not mount!\n");
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err = PTR_ERR(sysfs_mnt);
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sysfs_mnt = NULL;
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unregister_filesystem(&sysfs_fs_type);
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goto out_err;
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}
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} else
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goto out_err;
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out:
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return err;
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out_err:
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kmem_cache_destroy(sysfs_dir_cachep);
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sysfs_dir_cachep = NULL;
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goto out;
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}
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#undef sysfs_get
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struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
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{
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return __sysfs_get(sd);
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}
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EXPORT_SYMBOL_GPL(sysfs_get);
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#undef sysfs_put
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void sysfs_put(struct sysfs_dirent *sd)
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{
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__sysfs_put(sd);
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}
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EXPORT_SYMBOL_GPL(sysfs_put);
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