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-rw-r--r--drivers/mtd/mtdsuper.c179
1 files changed, 179 insertions, 0 deletions
diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
new file mode 100644
index 0000000000..b7e3763c47
--- /dev/null
+++ b/drivers/mtd/mtdsuper.c
@@ -0,0 +1,179 @@
+// 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 */
+ 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);