root/fs/sysfs/mount.c

DEFINITIONS

1. sysfs_fill_super
2. sysfs_get_sb
3. sysfs_init

/*
 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 *
 * This file is released under the GPLv2.
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#define DEBUG 

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>

#include "sysfs.h"

/* Random magic number */
#define SYSFS_MAGIC 0x62656572

static struct vfsmount *sysfs_mount;
struct super_block * sysfs_sb = NULL;
struct kmem_cache *sysfs_dir_cachep;

static const struct super_operations sysfs_ops = {
        .statfs         = simple_statfs,
        .drop_inode     = generic_delete_inode,
};

struct sysfs_dirent sysfs_root = {
        .s_name         = "",
        .s_count        = ATOMIC_INIT(1),
        .s_flags        = SYSFS_DIR,
        .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
        .s_ino          = 1,
};

static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
{
        struct inode *inode;
        struct dentry *root;

        sb->s_blocksize = PAGE_CACHE_SIZE;
        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
        sb->s_magic = SYSFS_MAGIC;
        sb->s_op = &sysfs_ops;
        sb->s_time_gran = 1;
        sysfs_sb = sb;

        /* get root inode, initialize and unlock it */
        inode = sysfs_get_inode(&sysfs_root);
        if (!inode) {
                pr_debug("sysfs: could not get root inode\n");
                return -ENOMEM;
        }

        /* instantiate and link root dentry */
        root = d_alloc_root(inode);
        if (!root) {
                pr_debug("%s: could not get root dentry!\n",__func__);
                iput(inode);
                return -ENOMEM;
        }
        root->d_fsdata = &sysfs_root;
        sb->s_root = root;
        return 0;
}

static int sysfs_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
        return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
}

static struct file_system_type sysfs_fs_type = {
        .name           = "sysfs",
        .get_sb         = sysfs_get_sb,
        .kill_sb        = kill_anon_super,
};

int __init sysfs_init(void)
{
        int err = -ENOMEM;

        sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
                                              sizeof(struct sysfs_dirent),
                                              0, 0, NULL);
        if (!sysfs_dir_cachep)
                goto out;

        err = sysfs_inode_init();
        if (err)
                goto out_err;

        err = register_filesystem(&sysfs_fs_type);
        if (!err) {
                sysfs_mount = kern_mount(&sysfs_fs_type);
                if (IS_ERR(sysfs_mount)) {
                        printk(KERN_ERR "sysfs: could not mount!\n");
                        err = PTR_ERR(sysfs_mount);
                        sysfs_mount = NULL;
                        unregister_filesystem(&sysfs_fs_type);
                        goto out_err;
                }
        } else
                goto out_err;
out:
        return err;
out_err:
        kmem_cache_destroy(sysfs_dir_cachep);
        sysfs_dir_cachep = NULL;
        goto out;
}