// 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" /* * 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; 	sb = sget_dev(fc, MKDEV(MTD_BLOCK_MAJOR, mtd->index));	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); 		/*		 * Would usually have been set with @sb_lock held but in		 * contrast to sb->s_bdev that's checked with only		 * @sb_lock held, nothing checks sb->s_mtd without also		 * holding sb->s_umount and we're holding sb->s_umount		 * here.		 */		sb->s_mtd = mtd;		sb->s_bdi = bdi_get(mtd_bdi); 		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 */			unsigned int mtdnr_val; 			if (kstrtouint(fc->source + 3, 0, &mtdnr_val) == 0) {				mtdnr = mtdnr_val;				/* It was a valid number */				pr_debug("MTDSB: mtd%%d, mtdnr %u\n", mtdnr_val);				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);