4a67a1bc0b
sysfs_get_inode ultimately calls sysfs_count_nlink when the a directory inode is fectched. sysfs_count_nlink needs to be called under the sysfs_mutex to guard against the unlikely but possible scenario that the root directory is changing as we are counting the number entries in it, and just in general to be consistent. Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
133 lines
2.9 KiB
C
133 lines
2.9 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 "sysfs.h"
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static struct vfsmount *sysfs_mount;
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struct super_block * sysfs_sb = NULL;
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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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};
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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,
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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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sysfs_sb = sb;
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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(&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_get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data, struct vfsmount *mnt)
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{
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return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
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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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.get_sb = sysfs_get_sb,
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.kill_sb = kill_anon_super,
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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_mount = kern_mount(&sysfs_fs_type);
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if (IS_ERR(sysfs_mount)) {
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printk(KERN_ERR "sysfs: could not mount!\n");
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err = PTR_ERR(sysfs_mount);
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sysfs_mount = 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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