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0f07100410
Provide a function, get_tree_mtd(), to replace mount_mtd(), using an fs_context struct to hold the parameters. Signed-off-by: David Howells <dhowells@redhat.com> cc: David Woodhouse <dwmw2@infradead.org> cc: Brian Norris <computersforpeace@gmail.com> cc: Boris Brezillon <bbrezillon@kernel.org> cc: Marek Vasut <marek.vasut@gmail.com> cc: Richard Weinberger <richard@nod.at> cc: linux-mtd@lists.infradead.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
396 lines
9.6 KiB
C
396 lines
9.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* MTD-based superblock management
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*
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* Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
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* Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
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*
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* Written by: David Howells <dhowells@redhat.com>
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* David Woodhouse <dwmw2@infradead.org>
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*/
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#include <linux/mtd/super.h>
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#include <linux/namei.h>
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#include <linux/export.h>
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#include <linux/ctype.h>
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#include <linux/slab.h>
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#include <linux/major.h>
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#include <linux/backing-dev.h>
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#include <linux/fs_context.h>
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#include "mtdcore.h"
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/*
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* compare superblocks to see if they're equivalent
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* - they are if the underlying MTD device is the same
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*/
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static int mtd_test_super(struct super_block *sb, struct fs_context *fc)
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{
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struct mtd_info *mtd = fc->sget_key;
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if (sb->s_mtd == fc->sget_key) {
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pr_debug("MTDSB: Match on device %d (\"%s\")\n",
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mtd->index, mtd->name);
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return 1;
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}
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pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
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sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
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return 0;
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}
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/*
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* mark the superblock by the MTD device it is using
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* - set the device number to be the correct MTD block device for pesuperstence
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* of NFS exports
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*/
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static int mtd_set_super(struct super_block *sb, struct fs_context *fc)
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{
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sb->s_mtd = fc->sget_key;
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sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
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sb->s_bdi = bdi_get(mtd_bdi);
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return 0;
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}
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/*
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* get a superblock on an MTD-backed filesystem
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*/
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static int mtd_get_sb(struct fs_context *fc,
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struct mtd_info *mtd,
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int (*fill_super)(struct super_block *,
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struct fs_context *))
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{
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struct super_block *sb;
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int ret;
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fc->sget_key = mtd;
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sb = sget_fc(fc, mtd_test_super, mtd_set_super);
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if (IS_ERR(sb))
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return PTR_ERR(sb);
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if (sb->s_root) {
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/* new mountpoint for an already mounted superblock */
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pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
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mtd->index, mtd->name);
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put_mtd_device(mtd);
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} else {
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/* fresh new superblock */
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pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
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mtd->index, mtd->name);
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ret = fill_super(sb, fc);
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if (ret < 0)
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goto error_sb;
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sb->s_flags |= SB_ACTIVE;
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}
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BUG_ON(fc->root);
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fc->root = dget(sb->s_root);
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return 0;
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error_sb:
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deactivate_locked_super(sb);
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return ret;
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}
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/*
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* get a superblock on an MTD-backed filesystem by MTD device number
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*/
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static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr,
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int (*fill_super)(struct super_block *,
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struct fs_context *))
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{
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struct mtd_info *mtd;
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mtd = get_mtd_device(NULL, mtdnr);
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if (IS_ERR(mtd)) {
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errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
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return PTR_ERR(mtd);
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}
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return mtd_get_sb(fc, mtd, fill_super);
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}
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/**
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* get_tree_mtd - Get a superblock based on a single MTD device
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* @fc: The filesystem context holding the parameters
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* @fill_super: Helper to initialise a new superblock
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*/
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int get_tree_mtd(struct fs_context *fc,
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int (*fill_super)(struct super_block *sb,
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struct fs_context *fc))
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{
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#ifdef CONFIG_BLOCK
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struct block_device *bdev;
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int ret, major;
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#endif
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int mtdnr;
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if (!fc->source)
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return invalf(fc, "No source specified");
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pr_debug("MTDSB: dev_name \"%s\"\n", fc->source);
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/* the preferred way of mounting in future; especially when
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* CONFIG_BLOCK=n - we specify the underlying MTD device by number or
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* by name, so that we don't require block device support to be present
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* in the kernel.
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*/
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if (fc->source[0] == 'm' &&
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fc->source[1] == 't' &&
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fc->source[2] == 'd') {
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if (fc->source[3] == ':') {
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struct mtd_info *mtd;
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/* mount by MTD device name */
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pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
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fc->source + 4);
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mtd = get_mtd_device_nm(fc->source + 4);
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if (!IS_ERR(mtd))
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return mtd_get_sb(fc, mtd, fill_super);
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errorf(fc, "MTD: MTD device with name \"%s\" not found",
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fc->source + 4);
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} else if (isdigit(fc->source[3])) {
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/* mount by MTD device number name */
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char *endptr;
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mtdnr = simple_strtoul(fc->source + 3, &endptr, 0);
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if (!*endptr) {
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/* It was a valid number */
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pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
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return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
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}
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}
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}
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#ifdef CONFIG_BLOCK
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/* try the old way - the hack where we allowed users to mount
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* /dev/mtdblock$(n) but didn't actually _use_ the blockdev
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*/
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bdev = lookup_bdev(fc->source);
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if (IS_ERR(bdev)) {
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ret = PTR_ERR(bdev);
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errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret);
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return ret;
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}
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pr_debug("MTDSB: lookup_bdev() returned 0\n");
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major = MAJOR(bdev->bd_dev);
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mtdnr = MINOR(bdev->bd_dev);
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bdput(bdev);
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if (major == MTD_BLOCK_MAJOR)
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return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
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#endif /* CONFIG_BLOCK */
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if (!(fc->sb_flags & SB_SILENT))
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errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
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fc->source);
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return -EINVAL;
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}
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EXPORT_SYMBOL_GPL(get_tree_mtd);
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/*
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* compare superblocks to see if they're equivalent
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* - they are if the underlying MTD device is the same
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*/
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static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
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{
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struct mtd_info *mtd = _mtd;
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if (sb->s_mtd == mtd) {
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pr_debug("MTDSB: Match on device %d (\"%s\")\n",
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mtd->index, mtd->name);
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return 1;
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}
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pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
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sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
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return 0;
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}
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/*
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* mark the superblock by the MTD device it is using
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* - set the device number to be the correct MTD block device for pesuperstence
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* of NFS exports
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*/
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static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
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{
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struct mtd_info *mtd = _mtd;
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sb->s_mtd = mtd;
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sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
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sb->s_bdi = bdi_get(mtd_bdi);
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return 0;
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}
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/*
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* get a superblock on an MTD-backed filesystem
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*/
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static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
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const char *dev_name, void *data,
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struct mtd_info *mtd,
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int (*fill_super)(struct super_block *, void *, int))
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{
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struct super_block *sb;
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int ret;
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sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
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if (IS_ERR(sb))
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goto out_error;
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if (sb->s_root)
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goto already_mounted;
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/* fresh new superblock */
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pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
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mtd->index, mtd->name);
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ret = fill_super(sb, data, flags & SB_SILENT ? 1 : 0);
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if (ret < 0) {
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deactivate_locked_super(sb);
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return ERR_PTR(ret);
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}
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/* go */
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sb->s_flags |= SB_ACTIVE;
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return dget(sb->s_root);
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/* new mountpoint for an already mounted superblock */
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already_mounted:
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pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
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mtd->index, mtd->name);
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put_mtd_device(mtd);
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return dget(sb->s_root);
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out_error:
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put_mtd_device(mtd);
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return ERR_CAST(sb);
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}
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/*
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* get a superblock on an MTD-backed filesystem by MTD device number
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*/
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static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
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const char *dev_name, void *data, int mtdnr,
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int (*fill_super)(struct super_block *, void *, int))
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{
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struct mtd_info *mtd;
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mtd = get_mtd_device(NULL, mtdnr);
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if (IS_ERR(mtd)) {
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pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
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return ERR_CAST(mtd);
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}
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return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
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}
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/*
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* set up an MTD-based superblock
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*/
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struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
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const char *dev_name, void *data,
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int (*fill_super)(struct super_block *, void *, int))
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{
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#ifdef CONFIG_BLOCK
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struct block_device *bdev;
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int ret, major;
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#endif
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int mtdnr;
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if (!dev_name)
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return ERR_PTR(-EINVAL);
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pr_debug("MTDSB: dev_name \"%s\"\n", dev_name);
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/* the preferred way of mounting in future; especially when
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* CONFIG_BLOCK=n - we specify the underlying MTD device by number or
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* by name, so that we don't require block device support to be present
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* in the kernel. */
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if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
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if (dev_name[3] == ':') {
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struct mtd_info *mtd;
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/* mount by MTD device name */
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pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
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dev_name + 4);
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mtd = get_mtd_device_nm(dev_name + 4);
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if (!IS_ERR(mtd))
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return mount_mtd_aux(
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fs_type, flags,
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dev_name, data, mtd,
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fill_super);
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printk(KERN_NOTICE "MTD:"
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" MTD device with name \"%s\" not found.\n",
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dev_name + 4);
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} else if (isdigit(dev_name[3])) {
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/* mount by MTD device number name */
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char *endptr;
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mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
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if (!*endptr) {
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/* It was a valid number */
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pr_debug("MTDSB: mtd%%d, mtdnr %d\n",
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mtdnr);
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return mount_mtd_nr(fs_type, flags,
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dev_name, data,
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mtdnr, fill_super);
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}
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}
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}
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#ifdef CONFIG_BLOCK
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/* try the old way - the hack where we allowed users to mount
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* /dev/mtdblock$(n) but didn't actually _use_ the blockdev
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*/
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bdev = lookup_bdev(dev_name);
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if (IS_ERR(bdev)) {
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ret = PTR_ERR(bdev);
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pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
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return ERR_PTR(ret);
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}
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pr_debug("MTDSB: lookup_bdev() returned 0\n");
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ret = -EINVAL;
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major = MAJOR(bdev->bd_dev);
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mtdnr = MINOR(bdev->bd_dev);
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bdput(bdev);
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if (major != MTD_BLOCK_MAJOR)
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goto not_an_MTD_device;
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return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
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not_an_MTD_device:
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#endif /* CONFIG_BLOCK */
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if (!(flags & SB_SILENT))
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printk(KERN_NOTICE
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"MTD: Attempt to mount non-MTD device \"%s\"\n",
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dev_name);
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return ERR_PTR(-EINVAL);
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}
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EXPORT_SYMBOL_GPL(mount_mtd);
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/*
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* destroy an MTD-based superblock
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*/
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void kill_mtd_super(struct super_block *sb)
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{
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generic_shutdown_super(sb);
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put_mtd_device(sb->s_mtd);
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sb->s_mtd = NULL;
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}
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EXPORT_SYMBOL_GPL(kill_mtd_super);
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