diff options
Diffstat (limited to 'drivers/mtd/mtdsuper.c')
| -rw-r--r-- | drivers/mtd/mtdsuper.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c new file mode 100644 index 000000000..c3e209837 --- /dev/null +++ b/drivers/mtd/mtdsuper.c @@ -0,0 +1,206 @@ +// 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/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 + struct block_device *bdev; + int ret, major; +#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 + */ + bdev = lookup_bdev(fc->source); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret); + return ret; + } + pr_debug("MTDSB: lookup_bdev() returned 0\n"); + + major = MAJOR(bdev->bd_dev); + mtdnr = MINOR(bdev->bd_dev); + bdput(bdev); + + if (major == MTD_BLOCK_MAJOR) + return mtd_get_sb_by_nr(fc, mtdnr, 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); |