Merge "Revert "init: do_mounts: Add a dummy definition for dm_table_put""

Boot time creation of mapped devices

===================================

It is possible to configure a device mapper device to act as the root

device for your system in two ways.

The first is to build an initial ramdisk which boots to a minimal

userspace which configures the device, then pivot_root(8) in to it.

For simple device mapper configurations, it is possible to boot directly

using the following kernel command line:

dm="<name> <uuid> <ro>,table line 1,...,table line n"

name = the name to associate with the device

	after boot, udev, if used, will use that name to label

	the device node.

uuid = may be 'none' or the UUID desired for the device.

ro = may be "ro" or "rw".  If "ro", the device and device table will be

	marked read-only.

Each table line may be as normal when using the dmsetup tool except for

two variations:

1. Any use of commas will be interpreted as a newline

2. Quotation marks cannot be escaped and cannot be used without

   terminating the dm= argument.

Unless renamed by udev, the device node created will be dm-0 as the

first minor number for the device-mapper is used during early creation.

Example

=======

- Booting to a linear array made up of user-mode linux block devices:

  dm="lroot none 0, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" \

  root=/dev/dm-0

Will boot to a rw dm-linear target of 8192 sectors split across two

block devices identified by their major:minor numbers.  After boot, udev

will rename this target to /dev/mapper/lroot (depending on the rules).

No uuid was assigned.

	BLACKFIN Blackfin architecture is enabled.

	CLK	Common clock infrastructure is enabled.

	CMA	Contiguous Memory Area support is enabled.

	DM	Device mapper support is enabled.

	DRM	Direct Rendering Management support is enabled.

	DYNAMIC_DEBUG Build in debug messages and enable them at runtime

	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled

	dis_ucode_ldr	[X86] Disable the microcode loader.

	dm=		[DM] Allows early creation of a device-mapper device.

			See Documentation/device-mapper/boot.txt.

	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,

			this option disables the debugging code at boot.

	dm_hash_exit();

}

/**

 * dm_ioctl_export - Permanently export a mapped device via the ioctl interface

 * @md: Pointer to mapped_device

 * @name: Buffer (size DM_NAME_LEN) for name

 * @uuid: Buffer (size DM_UUID_LEN) for uuid or NULL if not desired

 */

int dm_ioctl_export(struct mapped_device *md, const char *name,

		    const char *uuid)

{

	int r = 0;

	struct hash_cell *hc;

	if (!md) {

		r = -ENXIO;

		goto out;

	}

	/* The name and uuid can only be set once. */

	mutex_lock(&dm_hash_cells_mutex);

	hc = dm_get_mdptr(md);

	mutex_unlock(&dm_hash_cells_mutex);

	if (hc) {

		DMERR("%s: already exported", dm_device_name(md));

		r = -ENXIO;

		goto out;

	}

	r = dm_hash_insert(name, uuid, md);

	if (r) {

		DMERR("%s: could not bind to '%s'", dm_device_name(md), name);

		goto out;

	}

	/* Let udev know we've changed. */

	dm_kobject_uevent(md, KOBJ_CHANGE, dm_get_event_nr(md));

out:

	return r;

}

/**

 * dm_copy_name_and_uuid - Copy mapped device name & uuid into supplied buffers

 * @md: Pointer to mapped_device

#include <linux/vmalloc.h>

#include <linux/blkdev.h>

#include <linux/namei.h>

#include <linux/mount.h>

#include <linux/ctype.h>

#include <linux/string.h>

#include <linux/slab.h>

void dm_set_mdptr(struct mapped_device *md, void *ptr);

void *dm_get_mdptr(struct mapped_device *md);

/*

 * Export the device via the ioctl interface (uses mdptr).

 */

int dm_ioctl_export(struct mapped_device *md, const char *name,

		    const char *uuid);

/*

 * A device can still be used while suspended, but I/O is deferred.

 */