1 files changed, 86 insertions, 131 deletions

diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
index e43fea896d1e..b7e3763c47f0 100644
--- a/drivers/mtd/mtdsuper.c
+++ b/drivers/mtd/mtdsuper.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /* MTD-based superblock management
  *
  * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved.
@@ -5,11 +6,6 @@
  *
  * 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>
@@ -19,159 +15,130 @@
 #include <linux/slab.h>
 #include <linux/major.h>
 #include <linux/backing-dev.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;
-}
-
-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
- *   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 = bdi_get(mtd_bdi);
-
-	return 0;
-}
+#include <linux/blkdev.h>
+#include <linux/fs_context.h>
+#include "mtdcore.h"
 
 /*
  * 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))
+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(fs_type, get_sb_mtd_compare, get_sb_mtd_set, flags, mtd);
+	sb = sget_dev(fc, MKDEV(MTD_BLOCK_MAJOR, mtd->index));
 	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);
+		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;
 	}
 
-	/* 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);
+	BUG_ON(fc->root);
+	fc->root = dget(sb->s_root);
+	return 0;
 
-out_error:
-	put_mtd_device(mtd);
-	return ERR_CAST(sb);
+error_sb:
+	deactivate_locked_super(sb);
+	return ret;
 }
 
 /*
  * 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))
+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)) {
-		pr_debug("MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
-		return ERR_CAST(mtd);
+		errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
+		return PTR_ERR(mtd);
 	}
 
-	return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
+	return mtd_get_sb(fc, mtd, fill_super);
 }
 
-/*
- * set up an MTD-based superblock
+/**
+ * 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
  */
-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))
+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;
+	dev_t dev;
+	int ret;
 #endif
 	int mtdnr;
 
-	if (!dev_name)
-		return ERR_PTR(-EINVAL);
+	if (!fc->source)
+		return invalf(fc, "No source specified");
 
-	pr_debug("MTDSB: dev_name \"%s\"\n", dev_name);
+	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 (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
-		if (dev_name[3] == ':') {
+	 * 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",
-			      dev_name + 4);
+				 fc->source + 4);
 
-			mtd = get_mtd_device_nm(dev_name + 4);
+			mtd = get_mtd_device_nm(fc->source + 4);
 			if (!IS_ERR(mtd))
-				return mount_mtd_aux(
-					fs_type, flags,
-					dev_name, data, mtd,
-					fill_super);
+				return mtd_get_sb(fc, mtd, fill_super);
 
-			printk(KERN_NOTICE "MTD:"
-			       " MTD device with name \"%s\" not found.\n",
-			       dev_name + 4);
+			errorf(fc, "MTD: MTD device with name \"%s\" not found",
+			       fc->source + 4);
 
-		} else if (isdigit(dev_name[3])) {
+		} else if (isdigit(fc->source[3])) {
 			/* mount by MTD device number name */
 			char *endptr;
 
-			mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
+			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 mount_mtd_nr(fs_type, flags,
-						     dev_name, data,
-						     mtdnr, fill_super);
+				pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr);
+				return mtd_get_sb_by_nr(fc, mtdnr, fill_super);
 			}
 		}
 	}
@@ -180,36 +147,24 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
 	/* 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);
+	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");
 
-	ret = -EINVAL;
-
-	major = MAJOR(bdev->bd_dev);
-	mtdnr = MINOR(bdev->bd_dev);
-	bdput(bdev);
+	if (MAJOR(dev) == MTD_BLOCK_MAJOR)
+		return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super);
 
-	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);
+	if (!(fc->sb_flags & SB_SILENT))
+		errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"",
+		       fc->source);
+	return -EINVAL;
 }
-
-EXPORT_SYMBOL_GPL(mount_mtd);
+EXPORT_SYMBOL_GPL(get_tree_mtd);
 
 /*
  * destroy an MTD-based superblock