Initial import

1 files changed, 220 insertions, 0 deletions

diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
new file mode 100644
index 000000000..20c02a3b7
--- /dev/null
+++ b/drivers/mtd/mtdsuper.c
@@ -0,0 +1,220 @@
+/* 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>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#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>
+
+/*
+ * compare superblocks to see if they're equivalent
+ * - they are if the underlying MTD device is the same
+ */
+static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
+{
+	struct mtd_info *mtd = _mtd;
+
+	if (sb->s_mtd == mtd) {
+		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 get_sb_mtd_set(struct super_block *sb, void *_mtd)
+{
+	struct mtd_info *mtd = _mtd;
+
+	sb->s_mtd = mtd;
+	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
+	sb->s_bdi = mtd->backing_dev_info;
+	return 0;
+}
+
+/*
+ * get a superblock on an MTD-backed filesystem
+ */
+static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
+			  const char *dev_name, void *data,
+			  struct mtd_info *mtd,
+			  int (*fill_super)(struct super_block *, void *, int))
+{
+	struct super_block *sb;
+	int ret;
+
+	sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
+	if (IS_ERR(sb))
+		goto out_error;
+
+	if (sb->s_root)
+		goto already_mounted;
+
+	/* fresh new superblock */
+	pr_debug("MTDSB: New superblock for device %d (\"%s\")\n",
+	      mtd->index, mtd->name);
+
+	ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
+	if (ret < 0) {
+		deactivate_locked_super(sb);
+		return ERR_PTR(ret);
+	}
+
+	/* go */
+	sb->s_flags |= MS_ACTIVE;
+	return dget(sb->s_root);
+
+	/* new mountpoint for an already mounted superblock */
+already_mounted:
+	pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n",
+	      mtd->index, mtd->name);
+	put_mtd_device(mtd);
+	return dget(sb->s_root);
+
+out_error:
+	put_mtd_device(mtd);
+	return ERR_CAST(sb);
+}
+
+/*
+ * get a superblock on an MTD-backed filesystem by MTD device number
+ */
+static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
+			 const char *dev_name, void *data, int mtdnr,
+			 int (*fill_super)(struct super_block *, void *, int))
+{
+	struct mtd_info *mtd;
+
+	mtd = get_mtd_device(NULL, mtdnr);
+	if (IS_ERR(mtd)) {
+		pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
+		return ERR_CAST(mtd);
+	}
+
+	return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
+}
+
+/*
+ * set up an MTD-based superblock
+ */
+struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
+	       const char *dev_name, void *data,
+	       int (*fill_super)(struct super_block *, void *, int))
+{
+#ifdef CONFIG_BLOCK
+	struct block_device *bdev;
+	int ret, major;
+#endif
+	int mtdnr;
+
+	if (!dev_name)
+		return ERR_PTR(-EINVAL);
+
+	pr_debug("MTDSB: dev_name \"%s\"\n", dev_name);
+
+	/* 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 (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
+		if (dev_name[3] == ':') {
+			struct mtd_info *mtd;
+
+			/* mount by MTD device name */
+			pr_debug("MTDSB: mtd:%%s, name \"%s\"\n",
+			      dev_name + 4);
+
+			mtd = get_mtd_device_nm(dev_name + 4);
+			if (!IS_ERR(mtd))
+				return mount_mtd_aux(
+					fs_type, flags,
+					dev_name, data, mtd,
+					fill_super);
+
+			printk(KERN_NOTICE "MTD:"
+			       " MTD device with name \"%s\" not found.\n",
+			       dev_name + 4);
+
+		} else if (isdigit(dev_name[3])) {
+			/* mount by MTD device number name */
+			char *endptr;
+
+			mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
+			if (!*endptr) {
+				/* It was a valid number */
+				pr_debug("MTDSB: mtd%%d, mtdnr %d\n",
+				      mtdnr);
+				return mount_mtd_nr(fs_type, flags,
+						     dev_name, data,
+						     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(dev_name);
+	if (IS_ERR(bdev)) {
+		ret = PTR_ERR(bdev);
+		pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
+		return ERR_PTR(ret);
+	}
+	pr_debug("MTDSB: lookup_bdev() returned 0\n");
+
+	ret = -EINVAL;
+
+	major = MAJOR(bdev->bd_dev);
+	mtdnr = MINOR(bdev->bd_dev);
+	bdput(bdev);
+
+	if (major != MTD_BLOCK_MAJOR)
+		goto not_an_MTD_device;
+
+	return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
+
+not_an_MTD_device:
+#endif /* CONFIG_BLOCK */
+
+	if (!(flags & MS_SILENT))
+		printk(KERN_NOTICE
+		       "MTD: Attempt to mount non-MTD device \"%s\"\n",
+		       dev_name);
+	return ERR_PTR(-EINVAL);
+}
+
+EXPORT_SYMBOL_GPL(mount_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);