linux-imx

/* MTD-based superblock management

 *

 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.

 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>

 *

 * Written by:  David Howells <dhowells@redhat.com>

 *              David Woodhouse <dwmw2@infradead.org>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */

​

#include <linux/mtd/super.h>

#include <linux/namei.h>

#include <linux/export.h>

#include <linux/ctype.h>

#include <linux/slab.h>

#include <linux/major.h>

#include <linux/backing-dev.h>

​

/*

 * compare superblocks to see if they're equivalent

 * - they are if the underlying MTD device is the same

 */

static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)

{

    struct mtd_info *mtd = _mtd;

​

    if (sb->s_mtd == mtd) {

        pr_debug("MTDSB: Match on device %d (\"%s\")\n",

              mtd->index, mtd->name);

        return 1;

    }

​

    pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",

          sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);

    return 0;

}

​

extern struct backing_dev_info *mtd_bdi;

​

/*

 * mark the superblock by the MTD device it is using

 * - set the device number to be the correct MTD block device for pesuperstence

 *   of NFS exports

 */

static int get_sb_mtd_set(struct super_block *sb, void *_mtd)

{

    struct mtd_info *mtd = _mtd;

​

    sb->s_mtd = mtd;

    sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);

    sb->s_bdi = bdi_get(mtd_bdi);

​

    return 0;

}

​

/*

 * get a superblock on an MTD-backed filesystem

 */

static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,

              const char *dev_name, void *data,

              struct mtd_info *mtd,

              int (*fill_super)(struct super_block *, void *, int))

{

    struct super_block *sb;

    int ret;

​

    sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);

    if (IS_ERR(sb))

        goto out_error;

​

    if (sb->s_root)

        goto already_mounted;

​

    /* fresh new superblock */

    pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",

          mtd->index, mtd->name);

​

    ret = fill_super(sb, data, flags & SB_SILENT ? 1 : 0);

    if (ret < 0) {

        deactivate_locked_super(sb);

        return ERR_PTR(ret);

    }

​

    /* go */

    sb->s_flags |= SB_ACTIVE;

    return dget(sb->s_root);

​

    /* new mountpoint for an already mounted superblock */