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Commit 0f071004 authored by David Howells's avatar David Howells Committed by Al Viro
Browse files

mtd: Provide fs_context-aware mount_mtd() replacement 



Provide a function, get_tree_mtd(), to replace mount_mtd(), using an
fs_context struct to hold the parameters.

Signed-off-by: default avatarDavid 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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent fe62c3a4

drivers/mtd/mtdcore.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

drivers/mtd/mtdsuper.c

+177 −2
Original line number Diff line number Diff line
@@ -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

include/linux/mtd/super.h

+3 −0
Original line number Diff line number Diff line
@@ -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));