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// SPDX-License-Identifier: GPL-2.0-or-later
/* 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>
*/
#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>
#include <linux/blkdev.h>
#include <linux/fs_context.h>
#include "mtdcore.h"
/*
* compare superblocks to see if they're equivalent
* - they are if the underlying MTD device is the same
*/
static int mtd_test_super(struct super_block *sb, struct fs_context *fc)
{
struct mtd_info *mtd = fc->sget_key;
if (sb->s_mtd == fc->sget_key) {
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;
}
/*
* 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 mtd_set_super(struct super_block *sb, struct fs_context *fc)
{
sb->s_mtd = fc->sget_key;
sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
sb->s_bdi = bdi_get(mtd_bdi);
return 0;
}
/*
* get a superblock on an MTD-backed filesystem
*/
static int mtd_get_sb(struct fs_context *fc,
struct mtd_info *mtd,
int (*fill_super)(struct super_block *,
struct fs_context *))
{
struct super_block *sb;
int ret;
fc->sget_key = mtd;
sb = sget_fc(fc, mtd_test_super, mtd_set_super);
if (IS_ERR(sb))
return PTR_ERR(sb);
if (sb->s_root) {
/* new mountpoint for an already mounted superblock */
pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
mtd->index, mtd->name);
put_mtd_device(mtd);
} else {
/* fresh new superblock */
pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
mtd->index, mtd->name);
ret = fill_super(sb, fc);
if (ret < 0)
goto error_sb;
sb->s_flags |= SB_ACTIVE;
}
BUG_ON(fc->root);
fc->root = dget(sb->s_root);
return 0;
error_sb:
deactivate_locked_super(sb);
return ret;
}
/*
* get a superblock on an MTD-backed filesystem by MTD device number
*/
static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
int (*fill_super)(struct super_block *,
struct fs_context *))
{
struct mtd_info *mtd;
mtd = get_mtd_device(NULL, mtdnr);
if (IS_ERR(mtd)) {
errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
return PTR_ERR(mtd);
}
return mtd_get_sb(fc, mtd, fill_super);
}
/**
* get_tree_mtd - Get a superblock based on a single MTD device
* @fc: The filesystem context holding the parameters
* @fill_super: Helper to initialise a new superblock
*/
int get_tree_mtd(struct fs_context *fc,
int (*fill_super)(struct super_block *sb,
struct fs_context *fc))
{
#ifdef CONFIG_BLOCK
dev_t dev;
int ret;
#endif
int mtdnr;
if (!fc->source)
return invalf(fc, "No source specified");
pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
/* 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 (fc->source[0] == 'm' &&
fc->source[1] == 't' &&
fc->source[2] == 'd') {
if (fc->source[3] == ':') {
struct mtd_info *mtd;
/* mount by MTD device name */
pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
fc->source + 4);
mtd = get_mtd_device_nm(fc->source + 4);
if (!IS_ERR(mtd))
return mtd_get_sb(fc, mtd, fill_super);
errorf(fc, "MTD: MTD device with name \"%s\" not found",
fc->source + 4);
} else if (isdigit(fc->source[3])) {
/* mount by MTD device number name */
char *endptr;
mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
if (!*endptr) {
/* It was a valid number */
pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
return mtd_get_sb_by_nr(fc, 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
*/
ret = lookup_bdev(fc->source, &dev);
if (ret) {
errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
return ret;
}
pr_debug("MTDSB: lookup_bdev() returned 0\n");
if (MAJOR(dev) == MTD_BLOCK_MAJOR)
return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);
#endif /* CONFIG_BLOCK */
if (!(fc->sb_flags & SB_SILENT))
errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
fc->source);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(get_tree_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);
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