[linux-block.git] / drivers / mtd / mtdsuper.c

// 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);
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
acaebfd8 DH	2	/* MTD-based superblock management
	3	*
	4	* Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
a1452a37 DW	5	* Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
a1452a37 DW	6	*
acaebfd8 DH	7	* Written by: David Howells <dhowells@redhat.com>
acaebfd8 DH	8	* David Woodhouse <dwmw2@infradead.org>
acaebfd8 DH	9	*/
	10
	11	#include <linux/mtd/super.h>
	12	#include <linux/namei.h>
f3bcc017	13	#include <linux/export.h>
acaebfd8	14	#include <linux/ctype.h>
6de94002	15	#include <linux/slab.h>
f83c3838	16	#include <linux/major.h>
fa06052d	17	#include <linux/backing-dev.h>
ccdf7741	18	#include <linux/blkdev.h>
0f071004 DH	19	#include <linux/fs_context.h>
	20	#include "mtdcore.h"
	21
	22	/*
	23	* compare superblocks to see if they're equivalent
	24	* - they are if the underlying MTD device is the same
	25	*/
	26	static int mtd_test_super(struct super_block sb, struct fs_context fc)
	27	{
	28	struct mtd_info *mtd = fc->sget_key;
	29
	30	if (sb->s_mtd == fc->sget_key) {
	31	pr_debug("MTDSB: Match on device %d (\"%s\")\n",
	32	mtd->index, mtd->name);
	33	return 1;
	34	}
	35
	36	pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
	37	sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
	38	return 0;
	39	}
	40
	41	/*
	42	* mark the superblock by the MTD device it is using
	43	* - set the device number to be the correct MTD block device for pesuperstence
	44	* of NFS exports
	45	*/
	46	static int mtd_set_super(struct super_block sb, struct fs_context fc)
	47	{
	48	sb->s_mtd = fc->sget_key;
	49	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
	50	sb->s_bdi = bdi_get(mtd_bdi);
	51	return 0;
	52	}
	53
	54	/*
	55	* get a superblock on an MTD-backed filesystem
	56	*/
	57	static int mtd_get_sb(struct fs_context *fc,
	58	struct mtd_info *mtd,
	59	int (fill_super)(struct super_block ,
	60	struct fs_context *))
	61	{
	62	struct super_block *sb;
	63	int ret;
	64
	65	fc->sget_key = mtd;
	66	sb = sget_fc(fc, mtd_test_super, mtd_set_super);
	67	if (IS_ERR(sb))
	68	return PTR_ERR(sb);
	69
	70	if (sb->s_root) {
	71	/* new mountpoint for an already mounted superblock */
	72	pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
	73	mtd->index, mtd->name);
	74	put_mtd_device(mtd);
	75	} else {
	76	/* fresh new superblock */
	77	pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
	78	mtd->index, mtd->name);
	79
	80	ret = fill_super(sb, fc);
	81	if (ret < 0)
	82	goto error_sb;
83
84	sb->s_flags \|= SB_ACTIVE;
85	}
86
87	BUG_ON(fc->root);
88	fc->root = dget(sb->s_root);
89	return 0;
90
91	error_sb:
92	deactivate_locked_super(sb);
93	return ret;
94	}
95
96	/*
97	* get a superblock on an MTD-backed filesystem by MTD device number
98	*/
99	static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
100	int (fill_super)(struct super_block ,
101	struct fs_context *))
102	{
103	struct mtd_info *mtd;
104
105	mtd = get_mtd_device(NULL, mtdnr);
106	if (IS_ERR(mtd)) {
107	errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
108	return PTR_ERR(mtd);
109	}
110
111	return mtd_get_sb(fc, mtd, fill_super);
112	}
113
114	/**
115	* get_tree_mtd - Get a superblock based on a single MTD device
116	* @fc: The filesystem context holding the parameters
117	* @fill_super: Helper to initialise a new superblock
118	*/
119	int get_tree_mtd(struct fs_context *fc,
120	int (fill_super)(struct super_block sb,
121	struct fs_context *fc))
122	{
123	#ifdef CONFIG_BLOCK
4e7b5671 CH	124	dev_t dev;
4e7b5671 CH	125	int ret;
0f071004 DH	126	#endif
	127	int mtdnr;
	128
	129	if (!fc->source)
	130	return invalf(fc, "No source specified");
	131
	132	pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
	133
	134	/* the preferred way of mounting in future; especially when
	135	* CONFIG_BLOCK=n - we specify the underlying MTD device by number or
	136	* by name, so that we don't require block device support to be present
	137	* in the kernel.
	138	*/
	139	if (fc->source[0] == 'm' &&
	140	fc->source[1] == 't' &&
	141	fc->source[2] == 'd') {
	142	if (fc->source[3] == ':') {
	143	struct mtd_info *mtd;
	144
	145	/* mount by MTD device name */
	146	pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
	147	fc->source + 4);
	148
	149	mtd = get_mtd_device_nm(fc->source + 4);
	150	if (!IS_ERR(mtd))
	151	return mtd_get_sb(fc, mtd, fill_super);
	152
	153	errorf(fc, "MTD: MTD device with name \"%s\" not found",
	154	fc->source + 4);
	155
	156	} else if (isdigit(fc->source[3])) {
	157	/* mount by MTD device number name */
	158	char *endptr;
	159
	160	mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
	161	if (!*endptr) {
	162	/* It was a valid number */
	163	pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
	164	return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
	165	}
	166	}
	167	}
	168
	169	#ifdef CONFIG_BLOCK
	170	/* try the old way - the hack where we allowed users to mount
	171	* /dev/mtdblock$(n) but didn't actually _use_ the blockdev
	172	*/
4e7b5671 CH	173	ret = lookup_bdev(fc->source, &dev);
4e7b5671 CH	174	if (ret) {
0f071004 DH	175	errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
	176	return ret;
	177	}
	178	pr_debug("MTDSB: lookup_bdev() returned 0\n");
	179
4e7b5671 CH	180	if (MAJOR(dev) == MTD_BLOCK_MAJOR)
4e7b5671 CH	181	return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);
0f071004 DH	182
	183	#endif /* CONFIG_BLOCK */
	184
	185	if (!(fc->sb_flags & SB_SILENT))
	186	errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
	187	fc->source);
	188	return -EINVAL;
	189	}
	190	EXPORT_SYMBOL_GPL(get_tree_mtd);
acaebfd8	191
acaebfd8 DH	192	/*
	193	* destroy an MTD-based superblock
	194	*/
	195	void kill_mtd_super(struct super_block *sb)
	196	{
	197	generic_shutdown_super(sb);
	198	put_mtd_device(sb->s_mtd);
	199	sb->s_mtd = NULL;
	200	}
	201
	202	EXPORT_SYMBOL_GPL(kill_mtd_super);