12874c5fdSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
2acaebfd8SDavid Howells /* MTD-based superblock management
3acaebfd8SDavid Howells *
4acaebfd8SDavid Howells * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
5a1452a37SDavid Woodhouse * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
6a1452a37SDavid Woodhouse *
7acaebfd8SDavid Howells * Written by: David Howells <dhowells@redhat.com>
8acaebfd8SDavid Howells * David Woodhouse <dwmw2@infradead.org>
9acaebfd8SDavid Howells */
10acaebfd8SDavid Howells
11acaebfd8SDavid Howells #include <linux/mtd/super.h>
12acaebfd8SDavid Howells #include <linux/namei.h>
13f3bcc017SPaul Gortmaker #include <linux/export.h>
14acaebfd8SDavid Howells #include <linux/ctype.h>
156de94002SJörn Engel #include <linux/slab.h>
16f83c3838SEzequiel Garcia #include <linux/major.h>
17fa06052dSJan Kara #include <linux/backing-dev.h>
18ccdf7741SChristoph Hellwig #include <linux/blkdev.h>
190f071004SDavid Howells #include <linux/fs_context.h>
200f071004SDavid Howells #include "mtdcore.h"
210f071004SDavid Howells
220f071004SDavid Howells /*
230f071004SDavid Howells * get a superblock on an MTD-backed filesystem
240f071004SDavid Howells */
mtd_get_sb(struct fs_context * fc,struct mtd_info * mtd,int (* fill_super)(struct super_block *,struct fs_context *))250f071004SDavid Howells static int mtd_get_sb(struct fs_context *fc,
260f071004SDavid Howells struct mtd_info *mtd,
270f071004SDavid Howells int (*fill_super)(struct super_block *,
280f071004SDavid Howells struct fs_context *))
290f071004SDavid Howells {
300f071004SDavid Howells struct super_block *sb;
310f071004SDavid Howells int ret;
320f071004SDavid Howells
33*ec952aa2SChristian Brauner sb = sget_dev(fc, MKDEV(MTD_BLOCK_MAJOR, mtd->index));
340f071004SDavid Howells if (IS_ERR(sb))
350f071004SDavid Howells return PTR_ERR(sb);
360f071004SDavid Howells
370f071004SDavid Howells if (sb->s_root) {
380f071004SDavid Howells /* new mountpoint for an already mounted superblock */
390f071004SDavid Howells pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
400f071004SDavid Howells mtd->index, mtd->name);
410f071004SDavid Howells put_mtd_device(mtd);
420f071004SDavid Howells } else {
430f071004SDavid Howells /* fresh new superblock */
440f071004SDavid Howells pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
450f071004SDavid Howells mtd->index, mtd->name);
460f071004SDavid Howells
47*ec952aa2SChristian Brauner /*
48*ec952aa2SChristian Brauner * Would usually have been set with @sb_lock held but in
49*ec952aa2SChristian Brauner * contrast to sb->s_bdev that's checked with only
50*ec952aa2SChristian Brauner * @sb_lock held, nothing checks sb->s_mtd without also
51*ec952aa2SChristian Brauner * holding sb->s_umount and we're holding sb->s_umount
52*ec952aa2SChristian Brauner * here.
53*ec952aa2SChristian Brauner */
54*ec952aa2SChristian Brauner sb->s_mtd = mtd;
55*ec952aa2SChristian Brauner sb->s_bdi = bdi_get(mtd_bdi);
56*ec952aa2SChristian Brauner
570f071004SDavid Howells ret = fill_super(sb, fc);
580f071004SDavid Howells if (ret < 0)
590f071004SDavid Howells goto error_sb;
600f071004SDavid Howells
610f071004SDavid Howells sb->s_flags |= SB_ACTIVE;
620f071004SDavid Howells }
630f071004SDavid Howells
640f071004SDavid Howells BUG_ON(fc->root);
650f071004SDavid Howells fc->root = dget(sb->s_root);
660f071004SDavid Howells return 0;
670f071004SDavid Howells
680f071004SDavid Howells error_sb:
690f071004SDavid Howells deactivate_locked_super(sb);
700f071004SDavid Howells return ret;
710f071004SDavid Howells }
720f071004SDavid Howells
730f071004SDavid Howells /*
740f071004SDavid Howells * get a superblock on an MTD-backed filesystem by MTD device number
750f071004SDavid Howells */
mtd_get_sb_by_nr(struct fs_context * fc,int mtdnr,int (* fill_super)(struct super_block *,struct fs_context *))760f071004SDavid Howells static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
770f071004SDavid Howells int (*fill_super)(struct super_block *,
780f071004SDavid Howells struct fs_context *))
790f071004SDavid Howells {
800f071004SDavid Howells struct mtd_info *mtd;
810f071004SDavid Howells
820f071004SDavid Howells mtd = get_mtd_device(NULL, mtdnr);
830f071004SDavid Howells if (IS_ERR(mtd)) {
840f071004SDavid Howells errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
850f071004SDavid Howells return PTR_ERR(mtd);
860f071004SDavid Howells }
870f071004SDavid Howells
880f071004SDavid Howells return mtd_get_sb(fc, mtd, fill_super);
890f071004SDavid Howells }
900f071004SDavid Howells
910f071004SDavid Howells /**
920f071004SDavid Howells * get_tree_mtd - Get a superblock based on a single MTD device
930f071004SDavid Howells * @fc: The filesystem context holding the parameters
940f071004SDavid Howells * @fill_super: Helper to initialise a new superblock
950f071004SDavid Howells */
get_tree_mtd(struct fs_context * fc,int (* fill_super)(struct super_block * sb,struct fs_context * fc))960f071004SDavid Howells int get_tree_mtd(struct fs_context *fc,
970f071004SDavid Howells int (*fill_super)(struct super_block *sb,
980f071004SDavid Howells struct fs_context *fc))
990f071004SDavid Howells {
1000f071004SDavid Howells #ifdef CONFIG_BLOCK
1014e7b5671SChristoph Hellwig dev_t dev;
1024e7b5671SChristoph Hellwig int ret;
1030f071004SDavid Howells #endif
1040f071004SDavid Howells int mtdnr;
1050f071004SDavid Howells
1060f071004SDavid Howells if (!fc->source)
1070f071004SDavid Howells return invalf(fc, "No source specified");
1080f071004SDavid Howells
1090f071004SDavid Howells pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
1100f071004SDavid Howells
1110f071004SDavid Howells /* the preferred way of mounting in future; especially when
1120f071004SDavid Howells * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
1130f071004SDavid Howells * by name, so that we don't require block device support to be present
1140f071004SDavid Howells * in the kernel.
1150f071004SDavid Howells */
1160f071004SDavid Howells if (fc->source[0] == 'm' &&
1170f071004SDavid Howells fc->source[1] == 't' &&
1180f071004SDavid Howells fc->source[2] == 'd') {
1190f071004SDavid Howells if (fc->source[3] == ':') {
1200f071004SDavid Howells struct mtd_info *mtd;
1210f071004SDavid Howells
1220f071004SDavid Howells /* mount by MTD device name */
1230f071004SDavid Howells pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
1240f071004SDavid Howells fc->source + 4);
1250f071004SDavid Howells
1260f071004SDavid Howells mtd = get_mtd_device_nm(fc->source + 4);
1270f071004SDavid Howells if (!IS_ERR(mtd))
1280f071004SDavid Howells return mtd_get_sb(fc, mtd, fill_super);
1290f071004SDavid Howells
1300f071004SDavid Howells errorf(fc, "MTD: MTD device with name \"%s\" not found",
1310f071004SDavid Howells fc->source + 4);
1320f071004SDavid Howells
1330f071004SDavid Howells } else if (isdigit(fc->source[3])) {
1340f071004SDavid Howells /* mount by MTD device number name */
1350f071004SDavid Howells char *endptr;
1360f071004SDavid Howells
1370f071004SDavid Howells mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
1380f071004SDavid Howells if (!*endptr) {
1390f071004SDavid Howells /* It was a valid number */
1400f071004SDavid Howells pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
1410f071004SDavid Howells return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
1420f071004SDavid Howells }
1430f071004SDavid Howells }
1440f071004SDavid Howells }
1450f071004SDavid Howells
1460f071004SDavid Howells #ifdef CONFIG_BLOCK
1470f071004SDavid Howells /* try the old way - the hack where we allowed users to mount
1480f071004SDavid Howells * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
1490f071004SDavid Howells */
1504e7b5671SChristoph Hellwig ret = lookup_bdev(fc->source, &dev);
1514e7b5671SChristoph Hellwig if (ret) {
1520f071004SDavid Howells errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
1530f071004SDavid Howells return ret;
1540f071004SDavid Howells }
1550f071004SDavid Howells pr_debug("MTDSB: lookup_bdev() returned 0\n");
1560f071004SDavid Howells
1574e7b5671SChristoph Hellwig if (MAJOR(dev) == MTD_BLOCK_MAJOR)
1584e7b5671SChristoph Hellwig return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);
1590f071004SDavid Howells
1600f071004SDavid Howells #endif /* CONFIG_BLOCK */
1610f071004SDavid Howells
1620f071004SDavid Howells if (!(fc->sb_flags & SB_SILENT))
1630f071004SDavid Howells errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
1640f071004SDavid Howells fc->source);
1650f071004SDavid Howells return -EINVAL;
1660f071004SDavid Howells }
1670f071004SDavid Howells EXPORT_SYMBOL_GPL(get_tree_mtd);
168acaebfd8SDavid Howells
169acaebfd8SDavid Howells /*
170acaebfd8SDavid Howells * destroy an MTD-based superblock
171acaebfd8SDavid Howells */
kill_mtd_super(struct super_block * sb)172acaebfd8SDavid Howells void kill_mtd_super(struct super_block *sb)
173acaebfd8SDavid Howells {
174acaebfd8SDavid Howells generic_shutdown_super(sb);
175acaebfd8SDavid Howells put_mtd_device(sb->s_mtd);
176acaebfd8SDavid Howells sb->s_mtd = NULL;
177acaebfd8SDavid Howells }
178acaebfd8SDavid Howells
179acaebfd8SDavid Howells EXPORT_SYMBOL_GPL(kill_mtd_super);
180