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1// SPDX-License-Identifier: GPL-2.0-or-later2/* MTD-based superblock management3 *4 * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.5 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>6 *7 * Written by: David Howells <dhowells@redhat.com>8 * David Woodhouse <dwmw2@infradead.org>9 */10 11#include <linux/mtd/super.h>12#include <linux/namei.h>13#include <linux/export.h>14#include <linux/ctype.h>15#include <linux/slab.h>16#include <linux/major.h>17#include <linux/backing-dev.h>18#include <linux/blkdev.h>19#include <linux/fs_context.h>20#include "mtdcore.h"21 22/*23 * get a superblock on an MTD-backed filesystem24 */25static int mtd_get_sb(struct fs_context *fc,26 struct mtd_info *mtd,27 int (*fill_super)(struct super_block *,28 struct fs_context *))29{30 struct super_block *sb;31 int ret;32 33 sb = sget_dev(fc, MKDEV(MTD_BLOCK_MAJOR, mtd->index));34 if (IS_ERR(sb))35 return PTR_ERR(sb);36 37 if (sb->s_root) {38 /* new mountpoint for an already mounted superblock */39 pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",40 mtd->index, mtd->name);41 put_mtd_device(mtd);42 } else {43 /* fresh new superblock */44 pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",45 mtd->index, mtd->name);46 47 /*48 * Would usually have been set with @sb_lock held but in49 * contrast to sb->s_bdev that's checked with only50 * @sb_lock held, nothing checks sb->s_mtd without also51 * holding sb->s_umount and we're holding sb->s_umount52 * here.53 */54 sb->s_mtd = mtd;55 sb->s_bdi = bdi_get(mtd_bdi);56 57 ret = fill_super(sb, fc);58 if (ret < 0)59 goto error_sb;60 61 sb->s_flags |= SB_ACTIVE;62 }63 64 BUG_ON(fc->root);65 fc->root = dget(sb->s_root);66 return 0;67 68error_sb:69 deactivate_locked_super(sb);70 return ret;71}72 73/*74 * get a superblock on an MTD-backed filesystem by MTD device number75 */76static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,77 int (*fill_super)(struct super_block *,78 struct fs_context *))79{80 struct mtd_info *mtd;81 82 mtd = get_mtd_device(NULL, mtdnr);83 if (IS_ERR(mtd)) {84 errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);85 return PTR_ERR(mtd);86 }87 88 return mtd_get_sb(fc, mtd, fill_super);89}90 91/**92 * get_tree_mtd - Get a superblock based on a single MTD device93 * @fc: The filesystem context holding the parameters94 * @fill_super: Helper to initialise a new superblock95 */96int get_tree_mtd(struct fs_context *fc,97 int (*fill_super)(struct super_block *sb,98 struct fs_context *fc))99{100#ifdef CONFIG_BLOCK101 dev_t dev;102 int ret;103#endif104 int mtdnr;105 106 if (!fc->source)107 return invalf(fc, "No source specified");108 109 pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);110 111 /* the preferred way of mounting in future; especially when112 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or113 * by name, so that we don't require block device support to be present114 * in the kernel.115 */116 if (fc->source[0] == 'm' &&117 fc->source[1] == 't' &&118 fc->source[2] == 'd') {119 if (fc->source[3] == ':') {120 struct mtd_info *mtd;121 122 /* mount by MTD device name */123 pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",124 fc->source + 4);125 126 mtd = get_mtd_device_nm(fc->source + 4);127 if (!IS_ERR(mtd))128 return mtd_get_sb(fc, mtd, fill_super);129 130 errorf(fc, "MTD: MTD device with name \"%s\" not found",131 fc->source + 4);132 133 } else if (isdigit(fc->source[3])) {134 /* mount by MTD device number name */135 char *endptr;136 137 mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);138 if (!*endptr) {139 /* It was a valid number */140 pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);141 return mtd_get_sb_by_nr(fc, mtdnr, fill_super);142 }143 }144 }145 146#ifdef CONFIG_BLOCK147 /* try the old way - the hack where we allowed users to mount148 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev149 */150 ret = lookup_bdev(fc->source, &dev);151 if (ret) {152 errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);153 return ret;154 }155 pr_debug("MTDSB: lookup_bdev() returned 0\n");156 157 if (MAJOR(dev) == MTD_BLOCK_MAJOR)158 return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);159 160#endif /* CONFIG_BLOCK */161 162 if (!(fc->sb_flags & SB_SILENT))163 errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",164 fc->source);165 return -EINVAL;166}167EXPORT_SYMBOL_GPL(get_tree_mtd);168 169/*170 * destroy an MTD-based superblock171 */172void kill_mtd_super(struct super_block *sb)173{174 generic_shutdown_super(sb);175 put_mtd_device(sb->s_mtd);176 sb->s_mtd = NULL;177}178 179EXPORT_SYMBOL_GPL(kill_mtd_super);180