diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h
index b31c868019adada77b86e028974203f09251739e..b5eefeabf310d7cb3780d8559e0ab040e549f91c 100644
--- a/drivers/mtd/mtdcore.h
+++ b/drivers/mtd/mtdcore.h
@@ -5,6 +5,7 @@
*/
extern struct mutex mtd_table_mutex;
+extern struct backing_dev_info *mtd_bdi;
struct mtd_info *__mtd_next_device(int i);
int __must_check add_mtd_device(struct mtd_info *mtd);
diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
index 4f042a3653ce221ad1bb04fdc6379fcb01d4d9ea..3f9a3b7b12c503f70eef981f075021ce6caa3bac 100644
--- a/drivers/mtd/mtdsuper.c
+++ b/drivers/mtd/mtdsuper.c
@@ -15,6 +15,183 @@
#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);
/*
* compare superblocks to see if they're equivalent
@@ -35,8 +212,6 @@ static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
return 0;
}
-extern struct backing_dev_info *mtd_bdi;
-
/*
* mark the superblock by the MTD device it is using
* - set the device number to be the correct MTD block device for pesuperstence
diff --git a/include/linux/mtd/super.h b/include/linux/mtd/super.h
index 056c9932c723b3f804ad8af285e07ea4d52803c4..42db3f8e813631e8eeecb5f368188ff59543a683 100644
--- a/include/linux/mtd/super.h
+++ b/include/linux/mtd/super.h
@@ -14,6 +14,9 @@
#include <linux/fs.h>
#include <linux/mount.h>
+extern int get_tree_mtd(struct fs_context *fc,
+ int (*fill_super)(struct super_block *sb,
+ struct fs_context *fc));
extern 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));