diff options
Diffstat (limited to 'drivers/mtd/mtdsuper.c')
| -rw-r--r-- | drivers/mtd/mtdsuper.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c new file mode 100644 index 000000000..d58a61c09 --- /dev/null +++ b/drivers/mtd/mtdsuper.c @@ -0,0 +1,224 @@ +/* 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 */ +already_mounted: + pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n", + mtd->index, mtd->name); + put_mtd_device(mtd); + return dget(sb->s_root); + +out_error: + put_mtd_device(mtd); + return ERR_CAST(sb); +} + +/* + * get a superblock on an MTD-backed filesystem by MTD device number + */ +static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags, + const char *dev_name, void *data, int mtdnr, + int (*fill_super)(struct super_block *, void *, int)) +{ + struct mtd_info *mtd; + + mtd = get_mtd_device(NULL, mtdnr); + if (IS_ERR(mtd)) { + pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr); + return ERR_CAST(mtd); + } + + return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super); +} + +/* + * set up an MTD-based superblock + */ +struct dentry *mount_mtd(struct file_system_type *fs_type, int flags, + const char *dev_name, void *data, + int (*fill_super)(struct super_block *, void *, int)) +{ +#ifdef CONFIG_BLOCK + struct block_device *bdev; + int ret, major; +#endif + int mtdnr; + + if (!dev_name) + return ERR_PTR(-EINVAL); + + pr_debug("MTDSB: dev_name \"%s\"\n", dev_name); + + /* the preferred way of mounting in future; especially when + * CONFIG_BLOCK=n - we specify the underlying MTD device by number or + * by name, so that we don't require block device support to be present + * in the kernel. */ + if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') { + if (dev_name[3] == ':') { + struct mtd_info *mtd; + + /* mount by MTD device name */ + pr_debug("MTDSB: mtd:%%s, name \"%s\"\n", + dev_name + 4); + + mtd = get_mtd_device_nm(dev_name + 4); + if (!IS_ERR(mtd)) + return mount_mtd_aux( + fs_type, flags, + dev_name, data, mtd, + fill_super); + + printk(KERN_NOTICE "MTD:" + " MTD device with name \"%s\" not found.\n", + dev_name + 4); + + } else if (isdigit(dev_name[3])) { + /* mount by MTD device number name */ + char *endptr; + + mtdnr = simple_strtoul(dev_name + 3, &endptr, 0); + if (!*endptr) { + /* It was a valid number */ + pr_debug("MTDSB: mtd%%d, mtdnr %d\n", + mtdnr); + return mount_mtd_nr(fs_type, flags, + dev_name, data, + mtdnr, fill_super); + } + } + } + +#ifdef CONFIG_BLOCK + /* try the old way - the hack where we allowed users to mount + * /dev/mtdblock$(n) but didn't actually _use_ the blockdev + */ + bdev = lookup_bdev(dev_name); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + pr_debug("MTDSB: lookup_bdev() returned %d\n", ret); + return ERR_PTR(ret); + } + pr_debug("MTDSB: lookup_bdev() returned 0\n"); + + ret = -EINVAL; + + major = MAJOR(bdev->bd_dev); + mtdnr = MINOR(bdev->bd_dev); + bdput(bdev); + + if (major != MTD_BLOCK_MAJOR) + goto not_an_MTD_device; + + return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super); + +not_an_MTD_device: +#endif /* CONFIG_BLOCK */ + + if (!(flags & SB_SILENT)) + printk(KERN_NOTICE + "MTD: Attempt to mount non-MTD device \"%s\"\n", + dev_name); + return ERR_PTR(-EINVAL); +} + +EXPORT_SYMBOL_GPL(mount_mtd); + +/* + * destroy an MTD-based superblock + */ +void kill_mtd_super(struct super_block *sb) +{ + generic_shutdown_super(sb); + put_mtd_device(sb->s_mtd); + sb->s_mtd = NULL; +} + +EXPORT_SYMBOL_GPL(kill_mtd_super); |