[PATCH] dm: v4 ioctl interface

From: Joe Thornber <thornber@sistina.com>

v4 of the ioctl interface.  Note there never was a v2 or a v3 except in an
unofficial EVMS way.

This works correctly with the 64-bit dev_t patches in -mm kernels.

There is now a config option to allow the user to select v1 or v4, it
defaults to v1.  dm-ioctl.[hc] just #includes dm-ioctl-v[14].[hc] depending
on the config option.

If you want to use v4 you will have to update your tools
(libdevmapper/lvm).  The latest tools at the time of writing are:

dmsetup + libdevmapper + replacement kernel patches for 2.4.20 & 2.4.21:

  ftp://ftp.sistina.com/pub/LVM2/device-mapper/device-mapper-testing-new-version4-interface.tgz

Updated LVM2 tools to work with the above:

  ftp://ftp.sistina.com/pub/LVM2/tools/LVM2.0-testing.tgz

drivers/md/Kconfig

@@ -145,5 +145,12 @@ config BLK_DEV_DM
 
 	  If unsure, say N.
 
+config DM_IOCTL_V4
+	bool "ioctl interface version 4"
+	depends on BLK_DEV_DM
+	---help---
+	  Recent tools use a new version of the ioctl interface, only
+          select this option if you intend using such tools.
+
 endmenu
 

drivers/md/dm-ioctl-v1.c

+/*
+ * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/miscdevice.h>
+#include <linux/dm-ioctl.h>
+#include <linux/init.h>
+#include <linux/wait.h>
+#include <linux/blk.h>
+#include <linux/slab.h>
+#include <linux/devfs_fs_kernel.h>
+
+#include <asm/uaccess.h>
+
+#define DM_DRIVER_EMAIL "dm@uk.sistina.com"
+
+/*-----------------------------------------------------------------
+ * The ioctl interface needs to be able to look up devices by
+ * name or uuid.
+ *---------------------------------------------------------------*/
+struct hash_cell {
+	struct list_head name_list;
+	struct list_head uuid_list;
+
+	char *name;
+	char *uuid;
+	struct mapped_device *md;
+};
+
+#define NUM_BUCKETS 64
+#define MASK_BUCKETS (NUM_BUCKETS - 1)
+static struct list_head _name_buckets[NUM_BUCKETS];
+static struct list_head _uuid_buckets[NUM_BUCKETS];
+
+void dm_hash_remove_all(void);
+
+/*
+ * Guards access to all three tables.
+ */
+static DECLARE_RWSEM(_hash_lock);
+
+static void init_buckets(struct list_head *buckets)
+{
+	unsigned int i;
+
+	for (i = 0; i < NUM_BUCKETS; i++)
+		INIT_LIST_HEAD(buckets + i);
+}
+
+int dm_hash_init(void)
+{
+	init_buckets(_name_buckets);
+	init_buckets(_uuid_buckets);
+	devfs_mk_dir(DM_DIR);
+	return 0;
+}
+
+void dm_hash_exit(void)
+{
+	dm_hash_remove_all();
+	devfs_remove(DM_DIR);
+}
+
+/*-----------------------------------------------------------------
+ * Hash function:
+ * We're not really concerned with the str hash function being
+ * fast since it's only used by the ioctl interface.
+ *---------------------------------------------------------------*/
+static unsigned int hash_str(const char *str)
+{
+	const unsigned int hash_mult = 2654435387U;
+	unsigned int h = 0;
+
+	while (*str)
+		h = (h + (unsigned int) *str++) * hash_mult;
+
+	return h & MASK_BUCKETS;
+}
+
+/*-----------------------------------------------------------------
+ * Code for looking up a device by name
+ *---------------------------------------------------------------*/
+static struct hash_cell *__get_name_cell(const char *str)
+{
+	struct list_head *tmp;
+	struct hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each (tmp, _name_buckets + h) {
+		hc = list_entry(tmp, struct hash_cell, name_list);
+		if (!strcmp(hc->name, str))
+			return hc;
+	}
+
+	return NULL;
+}
+
+static struct hash_cell *__get_uuid_cell(const char *str)
+{
+	struct list_head *tmp;
+	struct hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each (tmp, _uuid_buckets + h) {
+		hc = list_entry(tmp, struct hash_cell, uuid_list);
+		if (!strcmp(hc->uuid, str))
+			return hc;
+	}
+
+	return NULL;
+}
+
+/*-----------------------------------------------------------------
+ * Inserting, removing and renaming a device.
+ *---------------------------------------------------------------*/
+static inline char *kstrdup(const char *str)
+{
+	char *r = kmalloc(strlen(str) + 1, GFP_KERNEL);
+	if (r)
+		strcpy(r, str);
+	return r;
+}
+
+static struct hash_cell *alloc_cell(const char *name, const char *uuid,
+				    struct mapped_device *md)
+{
+	struct hash_cell *hc;
+
+	hc = kmalloc(sizeof(*hc), GFP_KERNEL);
+	if (!hc)
+		return NULL;
+
+	hc->name = kstrdup(name);
+	if (!hc->name) {
+		kfree(hc);
+		return NULL;
+	}
+
+	if (!uuid)
+		hc->uuid = NULL;
+
+	else {
+		hc->uuid = kstrdup(uuid);
+		if (!hc->uuid) {
+			kfree(hc->name);
+			kfree(hc);
+			return NULL;
+		}
+	}
+
+	INIT_LIST_HEAD(&hc->name_list);
+	INIT_LIST_HEAD(&hc->uuid_list);
+	hc->md = md;
+	return hc;
+}
+
+static void free_cell(struct hash_cell *hc)
+{
+	if (hc) {
+		kfree(hc->name);
+		kfree(hc->uuid);
+		kfree(hc);
+	}
+}
+
+/*
+ * devfs stuff.
+ */
+static int register_with_devfs(struct hash_cell *hc)
+{
+	struct gendisk *disk = dm_disk(hc->md);
+
+	devfs_mk_bdev(MKDEV(disk->major, disk->first_minor),
+		       S_IFBLK | S_IRUSR | S_IWUSR | S_IRGRP,
+		       DM_DIR "/%s", hc->name);
+	return 0;
+}
+
+static int unregister_with_devfs(struct hash_cell *hc)
+{
+	devfs_remove(DM_DIR"/%s", hc->name);
+	return 0;
+}
+
+/*
+ * The kdev_t and uuid of a device can never change once it is
+ * initially inserted.
+ */
+int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
+{
+	struct hash_cell *cell;
+
+	/*
+	 * Allocate the new cells.
+	 */
+	cell = alloc_cell(name, uuid, md);
+	if (!cell)
+		return -ENOMEM;
+
+	/*
+	 * Insert the cell into all three hash tables.
+	 */
+	down_write(&_hash_lock);
+	if (__get_name_cell(name))
+		goto bad;
+
+	list_add(&cell->name_list, _name_buckets + hash_str(name));
+
+	if (uuid) {
+		if (__get_uuid_cell(uuid)) {
+			list_del(&cell->name_list);
+			goto bad;
+		}
+		list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
+	}
+	register_with_devfs(cell);
+	dm_get(md);
+	up_write(&_hash_lock);
+
+	return 0;
+
+ bad:
+	up_write(&_hash_lock);
+	free_cell(cell);
+	return -EBUSY;
+}
+
+void __hash_remove(struct hash_cell *hc)
+{
+	/* remove from the dev hash */
+	list_del(&hc->uuid_list);
+	list_del(&hc->name_list);
+	unregister_with_devfs(hc);
+	dm_put(hc->md);
+	free_cell(hc);
+}
+
+void dm_hash_remove_all(void)
+{
+	int i;
+	struct hash_cell *hc;
+	struct list_head *tmp, *n;
+
+	down_write(&_hash_lock);
+	for (i = 0; i < NUM_BUCKETS; i++) {
+		list_for_each_safe (tmp, n, _name_buckets + i) {
+			hc = list_entry(tmp, struct hash_cell, name_list);
+			__hash_remove(hc);
+		}
+	}
+	up_write(&_hash_lock);
+}
+
+int dm_hash_rename(const char *old, const char *new)
+{
+	char *new_name, *old_name;
+	struct hash_cell *hc;
+
+	/*
+	 * duplicate new.
+	 */
+	new_name = kstrdup(new);
+	if (!new_name)
+		return -ENOMEM;
+
+	down_write(&_hash_lock);
+
+	/*
+	 * Is new free ?
+	 */
+	hc = __get_name_cell(new);
+	if (hc) {
+		DMWARN("asked to rename to an already existing name %s -> %s",
+		       old, new);
+		up_write(&_hash_lock);
+		kfree(new_name);
+		return -EBUSY;
+	}
+
+	/*
+	 * Is there such a device as 'old' ?
+	 */
+	hc = __get_name_cell(old);
+	if (!hc) {
+		DMWARN("asked to rename a non existent device %s -> %s",
+		       old, new);
+		up_write(&_hash_lock);
+		kfree(new_name);
+		return -ENXIO;
+	}
+
+	/*
+	 * rename and move the name cell.
+	 */
+	unregister_with_devfs(hc);
+
+	list_del(&hc->name_list);
+	old_name = hc->name;
+	hc->name = new_name;
+	list_add(&hc->name_list, _name_buckets + hash_str(new_name));
+
+	/* rename the device node in devfs */
+	register_with_devfs(hc);
+
+	up_write(&_hash_lock);
+	kfree(old_name);
+	return 0;
+}
+
+
+/*-----------------------------------------------------------------
+ * Implementation of the ioctl commands
+ *---------------------------------------------------------------*/
+
+/*
+ * All the ioctl commands get dispatched to functions with this
+ * prototype.
+ */
+typedef int (*ioctl_fn)(struct dm_ioctl *param, struct dm_ioctl *user);
+
+/*
+ * Check a string doesn't overrun the chunk of
+ * memory we copied from userland.
+ */
+static int valid_str(char *str, void *begin, void *end)
+{
+	while (((void *) str >= begin) && ((void *) str < end))
+		if (!*str++)
+			return 0;
+
+	return -EINVAL;
+}
+
+static int next_target(struct dm_target_spec *last, uint32_t next,
+		       void *begin, void *end,
+		       struct dm_target_spec **spec, char **params)
+{
+	*spec = (struct dm_target_spec *)
+	    ((unsigned char *) last + next);
+	*params = (char *) (*spec + 1);
+
+	if (*spec < (last + 1) || ((void *) *spec > end))
+		return -EINVAL;
+
+	return valid_str(*params, begin, end);
+}
+
+static int populate_table(struct dm_table *table, struct dm_ioctl *args)
+{
+	int r, first = 1;
+	unsigned int i = 0;
+	struct dm_target_spec *spec;
+	char *params;
+	void *begin, *end;
+
+	if (!args->target_count) {
+		DMWARN("populate_table: no targets specified");
+		return -EINVAL;
+	}
+
+	begin = (void *) args;
+	end = begin + args->data_size;
+
+	for (i = 0; i < args->target_count; i++) {
+
+		if (first)
+			r = next_target((struct dm_target_spec *) args,
+					args->data_start,
+					begin, end, &spec, &params);
+		else
+			r = next_target(spec, spec->next, begin, end,
+					&spec, &params);
+
+		if (r) {
+			DMWARN("unable to find target");
+			return -EINVAL;
+		}
+
+		r = dm_table_add_target(table, spec->target_type,
+					(sector_t) spec->sector_start,
+					(sector_t) spec->length,
+					params);
+		if (r) {
+			DMWARN("internal error adding target to table");
+			return -EINVAL;
+		}
+
+		first = 0;
+	}
+
+	return dm_table_complete(table);
+}
+
+/*
+ * Round up the ptr to the next 'align' boundary.  Obviously
+ * 'align' must be a power of 2.
+ */
+static inline void *align_ptr(void *ptr, unsigned int align)
+{
+	align--;
+	return (void *) (((unsigned long) (ptr + align)) & ~align);
+}
+
+/*
+ * Copies a dm_ioctl and an optional additional payload to
+ * userland.
+ */
+static int results_to_user(struct dm_ioctl *user, struct dm_ioctl *param,
+			   void *data, uint32_t len)
+{
+	int r;
+	void *ptr = NULL;
+
+	if (data) {
+		ptr = align_ptr(user + 1, sizeof(unsigned long));
+		param->data_start = ptr - (void *) user;
+	}
+
+	/*
+	 * The version number has already been filled in, so we
+	 * just copy later fields.
+	 */
+	r = copy_to_user(&user->data_size, &param->data_size,
+			 sizeof(*param) - sizeof(param->version));
+	if (r)
+		return -EFAULT;
+
+	if (data) {
+		if (param->data_start + len > param->data_size)
+			return -ENOSPC;
+
+		if (copy_to_user(ptr, data, len))
+			r = -EFAULT;
+	}
+
+	return r;
+}
+
+/*
+ * Fills in a dm_ioctl structure, ready for sending back to
+ * userland.
+ */
+static int __info(struct mapped_device *md, struct dm_ioctl *param)
+{
+	struct dm_table *table;
+	struct block_device *bdev;
+	struct gendisk *disk = dm_disk(md);
+
+	param->flags = DM_EXISTS_FLAG;
+	if (dm_suspended(md))
+		param->flags |= DM_SUSPEND_FLAG;
+
+	bdev = bdget_disk(disk, 0);
+	if (!bdev)
+		return -ENXIO;
+
+	param->dev = bdev->bd_dev;
+	param->open_count = bdev->bd_openers;
+	bdput(bdev);
+
+	if (disk->policy)
+		param->flags |= DM_READONLY_FLAG;
+
+	table = dm_get_table(md);
+	param->target_count = dm_table_get_num_targets(table);
+	dm_table_put(table);
+
+	return 0;
+}
+
+/*
+ * Always use UUID for lookups if it's present, otherwise use name.
+ */
+static inline struct mapped_device *find_device(struct dm_ioctl *param)
+{
+	struct hash_cell *hc;
+	struct mapped_device *md = NULL;
+
+	down_read(&_hash_lock);
+	hc = *param->uuid ? __get_uuid_cell(param->uuid) :
+		__get_name_cell(param->name);
+	if (hc) {
+		md = hc->md;
+
+		/*
+		 * Sneakily write in both the name and the uuid
+		 * while we have the cell.
+		 */
+		strlcpy(param->name, hc->name, sizeof(param->name));
+		if (hc->uuid)
+			strlcpy(param->uuid, hc->uuid, sizeof(param->uuid));
+		else
+			param->uuid[0] = '\0';
+
+		dm_get(md);
+	}
+	up_read(&_hash_lock);
+
+	return md;
+}
+
+#define ALIGNMENT sizeof(int)
+static void *_align(void *ptr, unsigned int a)
+{
+	register unsigned long align = --a;
+
+	return (void *) (((unsigned long) ptr + align) & ~align);
+}
+
+/*
+ * Copies device info back to user space, used by
+ * the create and info ioctls.
+ */
+static int info(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	struct mapped_device *md;
+
+	param->flags = 0;
+
+	md = find_device(param);
+	if (!md)
+		/*
+		 * Device not found - returns cleared exists flag.
+		 */
+		goto out;
+
+	__info(md, param);
+	dm_put(md);
+
+      out:
+	return results_to_user(user, param, NULL, 0);
+}
+
+static inline int get_mode(struct dm_ioctl *param)
+{
+	int mode = FMODE_READ | FMODE_WRITE;
+
+	if (param->flags & DM_READONLY_FLAG)
+		mode = FMODE_READ;
+
+	return mode;
+}
+
+static int check_name(const char *name)
+{
+	if (name[0] == '/') {
+		DMWARN("invalid device name");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int create(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	int r;
+	struct dm_table *t;
+	struct mapped_device *md;
+
+	r = check_name(param->name);
+	if (r)
+		return r;
+
+	r = dm_table_create(&t, get_mode(param));
+	if (r)
+		return r;
+
+	r = populate_table(t, param);
+	if (r) {
+		dm_table_put(t);
+		return r;
+	}
+
+	if (param->flags & DM_PERSISTENT_DEV_FLAG)
+		r = dm_create_with_minor(minor(to_kdev_t(param->dev)), &md);
+	else
+		r = dm_create(&md);
+
+	if (r) {
+		dm_table_put(t);
+		return r;
+	}
+
+	/* suspend the device */
+	r = dm_suspend(md);
+	if (r) {
+		DMWARN("suspend failed");
+		dm_table_put(t);
+		dm_put(md);
+		return r;
+	}
+	/* swap in the table */
+	r = dm_swap_table(md, t);
+	if (r) {
+		DMWARN("table swap failed");
+		dm_table_put(t);
+		dm_put(md);
+		return r;
+	}
+
+	/* resume the device */
+	r = dm_resume(md);
+	if (r) {
+		DMWARN("resume failed");
+		dm_table_put(t);
+		dm_put(md);
+		return r;
+	}
+
+	dm_table_put(t);	/* md will have grabbed its own reference */
+
+	set_disk_ro(dm_disk(md), (param->flags & DM_READONLY_FLAG) ? 1 : 0);
+	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
+	dm_put(md);
+
+	return r ? r : info(param, user);
+}
+
+/*
+ * Build up the status struct for each target
+ */
+static int __status(struct mapped_device *md, struct dm_ioctl *param,
+		    char *outbuf, size_t *len)
+{
+	unsigned int i, num_targets;
+	struct dm_target_spec *spec;
+	char *outptr;
+	status_type_t type;
+	struct dm_table *table = dm_get_table(md);
+
+	if (param->flags & DM_STATUS_TABLE_FLAG)
+		type = STATUSTYPE_TABLE;
+	else
+		type = STATUSTYPE_INFO;
+
+	outptr = outbuf;
+
+	/* Get all the target info */
+	num_targets = dm_table_get_num_targets(table);
+	for (i = 0; i < num_targets; i++) {
+		struct dm_target *ti = dm_table_get_target(table, i);
+
+		if (outptr - outbuf +
+		    sizeof(struct dm_target_spec) > param->data_size) {
+			dm_table_put(table);
+			return -ENOMEM;
+		}
+
+		spec = (struct dm_target_spec *) outptr;
+
+		spec->status = 0;
+		spec->sector_start = ti->begin;
+		spec->length = ti->len;
+		strlcpy(spec->target_type, ti->type->name,
+			sizeof(spec->target_type));
+
+		outptr += sizeof(struct dm_target_spec);
+
+		/* Get the status/table string from the target driver */
+		if (ti->type->status)
+			ti->type->status(ti, type, outptr,
+					 outbuf + param->data_size - outptr);
+		else
+			outptr[0] = '\0';
+
+		outptr += strlen(outptr) + 1;
+		_align(outptr, ALIGNMENT);
+		spec->next = outptr - outbuf;
+	}
+
+	param->target_count = num_targets;
+	*len = outptr - outbuf;
+	dm_table_put(table);
+
+	return 0;
+}
+
+/*
+ * Return the status of a device as a text string for each
+ * target.
+ */
+static int get_status(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	struct mapped_device *md;
+	size_t len = 0;
+	int ret;
+	char *outbuf = NULL;
+
+	md = find_device(param);
+	if (!md)
+		/*
+		 * Device not found - returns cleared exists flag.
+		 */
+		goto out;
+
+	/* We haven't a clue how long the resultant data will be so
+	   just allocate as much as userland has allowed us and make sure
+	   we don't overun it */
+	outbuf = kmalloc(param->data_size, GFP_KERNEL);
+	if (!outbuf)
+		goto out;
+	/*
+	 * Get the status of all targets
+	 */
+	__status(md, param, outbuf, &len);
+
+	/*
+	 * Setup the basic dm_ioctl structure.
+	 */
+	__info(md, param);
+
+      out:
+	if (md)
+		dm_put(md);
+
+	ret = results_to_user(user, param, outbuf, len);
+
+	if (outbuf)
+		kfree(outbuf);
+
+	return ret;
+}
+
+/*
+ * Wait for a device to report an event
+ */
+static int wait_device_event(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	struct mapped_device *md;
+	DECLARE_WAITQUEUE(wq, current);
+
+	md = find_device(param);
+	if (!md)
+		/*
+		 * Device not found - returns cleared exists flag.
+		 */
+		goto out;
+
+	/*
+	 * Setup the basic dm_ioctl structure.
+	 */
+	__info(md, param);
+
+	/*
+	 * Wait for a notification event
+	 */
+	set_current_state(TASK_INTERRUPTIBLE);
+ 	if (!dm_add_wait_queue(md, &wq, dm_get_event_nr(md))) {
+ 		schedule();
+ 		dm_remove_wait_queue(md, &wq);
+ 	}
+  	set_current_state(TASK_RUNNING);
+ 	dm_put(md);
+
+      out:
+	return results_to_user(user, param, NULL, 0);
+}
+
+/*
+ * Retrieves a list of devices used by a particular dm device.
+ */
+static int dep(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	int r;
+	unsigned int count;
+	struct mapped_device *md;
+	struct list_head *tmp;
+	size_t len = 0;
+	struct dm_target_deps *deps = NULL;
+	struct dm_table *table;
+
+	md = find_device(param);
+	if (!md)
+		goto out;
+	table = dm_get_table(md);
+
+	/*
+	 * Setup the basic dm_ioctl structure.
+	 */
+	__info(md, param);
+
+	/*
+	 * Count the devices.
+	 */
+	count = 0;
+	list_for_each(tmp, dm_table_get_devices(table))
+	    count++;
+
+	/*
+	 * Allocate a kernel space version of the dm_target_status
+	 * struct.
+	 */
+	if (array_too_big(sizeof(*deps), sizeof(*deps->dev), count)) {
+		dm_table_put(table);
+		dm_put(md);
+		return -ENOMEM;
+	}
+
+	len = sizeof(*deps) + (sizeof(*deps->dev) * count);
+	deps = kmalloc(len, GFP_KERNEL);
+	if (!deps) {
+		dm_table_put(table);
+		dm_put(md);
+		return -ENOMEM;
+	}
+
+	/*
+	 * Fill in the devices.
+	 */
+	deps->count = count;
+	count = 0;
+	list_for_each(tmp, dm_table_get_devices(table)) {
+		struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
+		deps->dev[count++] = dd->bdev->bd_dev;
+	}
+	dm_table_put(table);
+	dm_put(md);
+
+      out:
+	r = results_to_user(user, param, deps, len);
+
+	kfree(deps);
+	return r;
+}
+
+static int remove(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	struct hash_cell *hc;
+
+	down_write(&_hash_lock);
+	hc = *param->uuid ? __get_uuid_cell(param->uuid) :
+		__get_name_cell(param->name);
+	if (!hc) {
+		DMWARN("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -EINVAL;
+	}
+
+	/*
+	 * You may ask the interface to drop its reference to an
+	 * in use device.  This is no different to unlinking a
+	 * file that someone still has open.  The device will not
+	 * actually be destroyed until the last opener closes it.
+	 * The name and uuid of the device (both are interface
+	 * properties) will be available for reuse immediately.
+	 *
+	 * You don't want to drop a _suspended_ device from the
+	 * interface, since that will leave you with no way of
+	 * resuming it.
+	 */
+	if (dm_suspended(hc->md)) {
+		DMWARN("refusing to remove a suspended device.");
+		up_write(&_hash_lock);
+		return -EPERM;
+	}
+
+	__hash_remove(hc);
+	up_write(&_hash_lock);
+	return 0;
+}
+
+static int remove_all(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	dm_hash_remove_all();
+	return 0;
+}
+
+static int suspend(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	int r;
+	struct mapped_device *md;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	if (param->flags & DM_SUSPEND_FLAG)
+		r = dm_suspend(md);
+	else
+		r = dm_resume(md);
+
+	dm_put(md);
+	return r;
+}
+
+static int reload(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	int r;
+	struct mapped_device *md;
+	struct dm_table *t;
+
+	r = dm_table_create(&t, get_mode(param));
+	if (r)
+		return r;
+
+	r = populate_table(t, param);
+	if (r) {
+		dm_table_put(t);
+		return r;
+	}
+
+	md = find_device(param);
+	if (!md) {
+		dm_table_put(t);
+		return -ENXIO;
+	}
+
+	r = dm_swap_table(md, t);
+	if (r) {
+		dm_put(md);
+		dm_table_put(t);
+		return r;
+	}
+	dm_table_put(t);	/* md will have taken its own reference */
+
+	set_disk_ro(dm_disk(md), (param->flags & DM_READONLY_FLAG) ? 1 : 0);
+	dm_put(md);
+
+	r = info(param, user);
+	return r;
+}
+
+static int rename(struct dm_ioctl *param, struct dm_ioctl *user)
+{
+	int r;
+	char *new_name = (char *) param + param->data_start;
+
+	if (valid_str(new_name, (void *) param,
+		      (void *) param + param->data_size)) {
+		DMWARN("Invalid new logical volume name supplied.");
+		return -EINVAL;
+	}
+
+	r = check_name(new_name);
+	if (r)
+		return r;
+
+	return dm_hash_rename(param->name, new_name);
+}
+
+
+/*-----------------------------------------------------------------
+ * Implementation of open/close/ioctl on the special char
+ * device.
+ *---------------------------------------------------------------*/
+static ioctl_fn lookup_ioctl(unsigned int cmd)
+{
+	static struct {
+		int cmd;
+		ioctl_fn fn;
+	} _ioctls[] = {
+		{DM_VERSION_CMD, NULL},	/* version is dealt with elsewhere */
+		{DM_REMOVE_ALL_CMD, remove_all},
+		{DM_DEV_CREATE_CMD, create},
+		{DM_DEV_REMOVE_CMD, remove},
+		{DM_DEV_RELOAD_CMD, reload},
+		{DM_DEV_RENAME_CMD, rename},
+		{DM_DEV_SUSPEND_CMD, suspend},
+		{DM_DEV_DEPS_CMD, dep},
+		{DM_DEV_STATUS_CMD, info},
+		{DM_TARGET_STATUS_CMD, get_status},
+		{DM_TARGET_WAIT_CMD, wait_device_event},
+	};
+
+	return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
+}
+
+/*
+ * As well as checking the version compatibility this always
+ * copies the kernel interface version out.
+ */
+static int check_version(unsigned int cmd, struct dm_ioctl *user)
+{
+	uint32_t version[3];
+	int r = 0;
+
+	if (copy_from_user(version, user->version, sizeof(version)))
+		return -EFAULT;
+
+	if ((DM_VERSION_MAJOR != version[0]) ||
+	    (DM_VERSION_MINOR < version[1])) {
+		DMWARN("ioctl interface mismatch: "
+		       "kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
+		       DM_VERSION_MAJOR, DM_VERSION_MINOR,
+		       DM_VERSION_PATCHLEVEL,
+		       version[0], version[1], version[2], cmd);
+		r = -EINVAL;
+	}
+
+	/*
+	 * Fill in the kernel version.
+	 */
+	version[0] = DM_VERSION_MAJOR;
+	version[1] = DM_VERSION_MINOR;
+	version[2] = DM_VERSION_PATCHLEVEL;
+	if (copy_to_user(user->version, version, sizeof(version)))
+		return -EFAULT;
+
+	return r;
+}
+
+static void free_params(struct dm_ioctl *param)
+{
+	vfree(param);
+}
+
+static int copy_params(struct dm_ioctl *user, struct dm_ioctl **param)
+{
+	struct dm_ioctl tmp, *dmi;
+
+	if (copy_from_user(&tmp, user, sizeof(tmp)))
+		return -EFAULT;
+
+	if (tmp.data_size < sizeof(tmp))
+		return -EINVAL;
+
+	dmi = (struct dm_ioctl *) vmalloc(tmp.data_size);
+	if (!dmi)
+		return -ENOMEM;
+
+	if (copy_from_user(dmi, user, tmp.data_size)) {
+		vfree(dmi);
+		return -EFAULT;
+	}
+
+	*param = dmi;
+	return 0;
+}
+
+static int validate_params(uint cmd, struct dm_ioctl *param)
+{
+	/* Ignores parameters */
+	if (cmd == DM_REMOVE_ALL_CMD)
+		return 0;
+
+	/* Unless creating, either name of uuid but not both */
+	if (cmd != DM_DEV_CREATE_CMD) {
+		if ((!*param->uuid && !*param->name) ||
+		    (*param->uuid && *param->name)) {
+			DMWARN("one of name or uuid must be supplied");
+			return -EINVAL;
+		}
+	}
+
+	/* Ensure strings are terminated */
+	param->name[DM_NAME_LEN - 1] = '\0';
+	param->uuid[DM_UUID_LEN - 1] = '\0';
+
+	return 0;
+}
+
+static int ctl_ioctl(struct inode *inode, struct file *file,
+		     uint command, ulong u)
+{
+	int r = 0;
+	unsigned int cmd;
+	struct dm_ioctl *param;
+	struct dm_ioctl *user = (struct dm_ioctl *) u;
+	ioctl_fn fn = NULL;
+
+	/* only root can play with this */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (_IOC_TYPE(command) != DM_IOCTL)
+		return -ENOTTY;
+
+	cmd = _IOC_NR(command);
+
+	/*
+	 * Check the interface version passed in.  This also
+	 * writes out the kernels interface version.
+	 */
+	r = check_version(cmd, user);
+	if (r)
+		return r;
+
+	/*
+	 * Nothing more to do for the version command.
+	 */
+	if (cmd == DM_VERSION_CMD)
+		return 0;
+
+	fn = lookup_ioctl(cmd);
+	if (!fn) {
+		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
+		return -ENOTTY;
+	}
+
+	/*
+	 * Copy the parameters into kernel space.
+	 */
+	r = copy_params(user, &param);
+	if (r)
+		return r;
+
+	r = validate_params(cmd, param);
+	if (r) {
+		free_params(param);
+		return r;
+	}
+
+	r = fn(param, user);
+	free_params(param);
+	return r;
+}
+
+static struct file_operations _ctl_fops = {
+	.ioctl	 = ctl_ioctl,
+	.owner	 = THIS_MODULE,
+};
+
+static struct miscdevice _dm_misc = {
+	.minor		= MISC_DYNAMIC_MINOR,
+	.name		= DM_NAME,
+	.devfs_name	= "mapper/control",
+	.fops		= &_ctl_fops
+};
+
+/*
+ * Create misc character device and link to DM_DIR/control.
+ */
+int __init dm_interface_init(void)
+{
+	int r;
+
+	r = dm_hash_init();
+	if (r)
+		return r;
+
+	r = misc_register(&_dm_misc);
+	if (r) {
+		DMERR("misc_register failed for control device");
+		dm_hash_exit();
+		return r;
+	}
+
+	DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
+	       DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
+	       DM_DRIVER_EMAIL);
+	return 0;
+
+	if (misc_deregister(&_dm_misc) < 0)
+		DMERR("misc_deregister failed for control device");
+	dm_hash_exit();
+	return r;
+}
+
+void dm_interface_exit(void)
+{
+	if (misc_deregister(&_dm_misc) < 0)
+		DMERR("misc_deregister failed for control device");
+	dm_hash_exit();
+}

drivers/md/dm-ioctl-v4.c

+/*
+ * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/miscdevice.h>
+#include <linux/init.h>
+#include <linux/wait.h>
+#include <linux/blk.h>
+#include <linux/slab.h>
+#include <linux/devfs_fs_kernel.h>
+
+#include <asm/uaccess.h>
+
+#define DM_DRIVER_EMAIL "dm@uk.sistina.com"
+
+/*-----------------------------------------------------------------
+ * The ioctl interface needs to be able to look up devices by
+ * name or uuid.
+ *---------------------------------------------------------------*/
+struct hash_cell {
+	struct list_head name_list;
+	struct list_head uuid_list;
+
+	char *name;
+	char *uuid;
+	struct mapped_device *md;
+	struct dm_table *new_map;
+};
+
+#define NUM_BUCKETS 64
+#define MASK_BUCKETS (NUM_BUCKETS - 1)
+static struct list_head _name_buckets[NUM_BUCKETS];
+static struct list_head _uuid_buckets[NUM_BUCKETS];
+
+void dm_hash_remove_all(void);
+
+/*
+ * Guards access to both hash tables.
+ */
+static DECLARE_RWSEM(_hash_lock);
+
+static void init_buckets(struct list_head *buckets)
+{
+	unsigned int i;
+
+	for (i = 0; i < NUM_BUCKETS; i++)
+		INIT_LIST_HEAD(buckets + i);
+}
+
+int dm_hash_init(void)
+{
+	init_buckets(_name_buckets);
+	init_buckets(_uuid_buckets);
+	devfs_mk_dir(DM_DIR);
+	return 0;
+}
+
+void dm_hash_exit(void)
+{
+	dm_hash_remove_all();
+	devfs_remove(DM_DIR);
+}
+
+/*-----------------------------------------------------------------
+ * Hash function:
+ * We're not really concerned with the str hash function being
+ * fast since it's only used by the ioctl interface.
+ *---------------------------------------------------------------*/
+static unsigned int hash_str(const char *str)
+{
+	const unsigned int hash_mult = 2654435387U;
+	unsigned int h = 0;
+
+	while (*str)
+		h = (h + (unsigned int) *str++) * hash_mult;
+
+	return h & MASK_BUCKETS;
+}
+
+/*-----------------------------------------------------------------
+ * Code for looking up a device by name
+ *---------------------------------------------------------------*/
+static struct hash_cell *__get_name_cell(const char *str)
+{
+	struct list_head *tmp;
+	struct hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each (tmp, _name_buckets + h) {
+		hc = list_entry(tmp, struct hash_cell, name_list);
+		if (!strcmp(hc->name, str))
+			return hc;
+	}
+
+	return NULL;
+}
+
+static struct hash_cell *__get_uuid_cell(const char *str)
+{
+	struct list_head *tmp;
+	struct hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each (tmp, _uuid_buckets + h) {
+		hc = list_entry(tmp, struct hash_cell, uuid_list);
+		if (!strcmp(hc->uuid, str))
+			return hc;
+	}
+
+	return NULL;
+}
+
+/*-----------------------------------------------------------------
+ * Inserting, removing and renaming a device.
+ *---------------------------------------------------------------*/
+static inline char *kstrdup(const char *str)
+{
+	char *r = kmalloc(strlen(str) + 1, GFP_KERNEL);
+	if (r)
+		strcpy(r, str);
+	return r;
+}
+
+static struct hash_cell *alloc_cell(const char *name, const char *uuid,
+				    struct mapped_device *md)
+{
+	struct hash_cell *hc;
+
+	hc = kmalloc(sizeof(*hc), GFP_KERNEL);
+	if (!hc)
+		return NULL;
+
+	hc->name = kstrdup(name);
+	if (!hc->name) {
+		kfree(hc);
+		return NULL;
+	}
+
+	if (!uuid)
+		hc->uuid = NULL;
+
+	else {
+		hc->uuid = kstrdup(uuid);
+		if (!hc->uuid) {
+			kfree(hc->name);
+			kfree(hc);
+			return NULL;
+		}
+	}
+
+	INIT_LIST_HEAD(&hc->name_list);
+	INIT_LIST_HEAD(&hc->uuid_list);
+	hc->md = md;
+	hc->new_map = NULL;
+	return hc;
+}
+
+static void free_cell(struct hash_cell *hc)
+{
+	if (hc) {
+		kfree(hc->name);
+		kfree(hc->uuid);
+		kfree(hc);
+	}
+}
+
+/*
+ * devfs stuff.
+ */
+static int register_with_devfs(struct hash_cell *hc)
+{
+	struct gendisk *disk = dm_disk(hc->md);
+
+	devfs_mk_bdev(MKDEV(disk->major, disk->first_minor),
+		      S_IFBLK | S_IRUSR | S_IWUSR | S_IRGRP,
+		      DM_DIR "/%s", hc->name);
+	return 0;
+}
+
+static int unregister_with_devfs(struct hash_cell *hc)
+{
+	devfs_remove(DM_DIR"/%s", hc->name);
+	return 0;
+}
+
+/*
+ * The kdev_t and uuid of a device can never change once it is
+ * initially inserted.
+ */
+int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
+{
+	struct hash_cell *cell;
+
+	/*
+	 * Allocate the new cells.
+	 */
+	cell = alloc_cell(name, uuid, md);
+	if (!cell)
+		return -ENOMEM;
+
+	/*
+	 * Insert the cell into both hash tables.
+	 */
+	down_write(&_hash_lock);
+	if (__get_name_cell(name))
+		goto bad;
+
+	list_add(&cell->name_list, _name_buckets + hash_str(name));
+
+	if (uuid) {
+		if (__get_uuid_cell(uuid)) {
+			list_del(&cell->name_list);
+			goto bad;
+		}
+		list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
+	}
+	register_with_devfs(cell);
+	dm_get(md);
+	up_write(&_hash_lock);
+
+	return 0;
+
+ bad:
+	up_write(&_hash_lock);
+	free_cell(cell);
+	return -EBUSY;
+}
+
+void __hash_remove(struct hash_cell *hc)
+{
+	/* remove from the dev hash */
+	list_del(&hc->uuid_list);
+	list_del(&hc->name_list);
+	unregister_with_devfs(hc);
+	dm_put(hc->md);
+	if (hc->new_map)
+		dm_table_put(hc->new_map);
+	free_cell(hc);
+}
+
+void dm_hash_remove_all(void)
+{
+	int i;
+	struct hash_cell *hc;
+	struct list_head *tmp, *n;
+
+	down_write(&_hash_lock);
+	for (i = 0; i < NUM_BUCKETS; i++) {
+		list_for_each_safe (tmp, n, _name_buckets + i) {
+			hc = list_entry(tmp, struct hash_cell, name_list);
+			__hash_remove(hc);
+		}
+	}
+	up_write(&_hash_lock);
+}
+
+int dm_hash_rename(const char *old, const char *new)
+{
+	char *new_name, *old_name;
+	struct hash_cell *hc;
+
+	/*
+	 * duplicate new.
+	 */
+	new_name = kstrdup(new);
+	if (!new_name)
+		return -ENOMEM;
+
+	down_write(&_hash_lock);
+
+	/*
+	 * Is new free ?
+	 */
+	hc = __get_name_cell(new);
+	if (hc) {
+		DMWARN("asked to rename to an already existing name %s -> %s",
+		       old, new);
+		up_write(&_hash_lock);
+		kfree(new_name);
+		return -EBUSY;
+	}
+
+	/*
+	 * Is there such a device as 'old' ?
+	 */
+	hc = __get_name_cell(old);
+	if (!hc) {
+		DMWARN("asked to rename a non existent device %s -> %s",
+		       old, new);
+		up_write(&_hash_lock);
+		kfree(new_name);
+		return -ENXIO;
+	}
+
+	/*
+	 * rename and move the name cell.
+	 */
+	unregister_with_devfs(hc);
+
+	list_del(&hc->name_list);
+	old_name = hc->name;
+	hc->name = new_name;
+	list_add(&hc->name_list, _name_buckets + hash_str(new_name));
+
+	/* rename the device node in devfs */
+	register_with_devfs(hc);
+
+	up_write(&_hash_lock);
+	kfree(old_name);
+	return 0;
+}
+
+/*-----------------------------------------------------------------
+ * Implementation of the ioctl commands
+ *---------------------------------------------------------------*/
+/*
+ * All the ioctl commands get dispatched to functions with this
+ * prototype.
+ */
+typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
+
+static int remove_all(struct dm_ioctl *param, size_t param_size)
+{
+	dm_hash_remove_all();
+	param->data_size = 0;
+	return 0;
+}
+
+/*
+ * Round up the ptr to an 8-byte boundary.
+ */
+#define ALIGN_MASK 7
+static inline void *align_ptr(void *ptr)
+{
+	return (void *) (((size_t) (ptr + ALIGN_MASK)) & ~ALIGN_MASK);
+}
+
+/*
+ * Retrieves the data payload buffer from an already allocated
+ * struct dm_ioctl.
+ */
+static void *get_result_buffer(struct dm_ioctl *param, size_t param_size,
+			       size_t *len)
+{
+	param->data_start = align_ptr(param + 1) - (void *) param;
+
+	if (param->data_start < param_size)
+		*len = param_size - param->data_start;
+	else
+		*len = 0;
+
+	return ((void *) param) + param->data_start;
+}
+
+static int list_devices(struct dm_ioctl *param, size_t param_size)
+{
+	unsigned int i;
+	struct hash_cell *hc;
+	size_t len, needed = 0;
+	struct gendisk *disk;
+	struct dm_name_list *nl, *old_nl = NULL;
+
+	down_write(&_hash_lock);
+
+	/*
+	 * Loop through all the devices working out how much
+	 * space we need.
+	 */
+	for (i = 0; i < NUM_BUCKETS; i++) {
+		list_for_each_entry (hc, _name_buckets + i, name_list) {
+			needed += sizeof(struct dm_name_list);
+			needed += strlen(hc->name);
+			needed += ALIGN_MASK;
+		}
+	}
+
+	/*
+	 * Grab our output buffer.
+	 */
+	nl = get_result_buffer(param, param_size, &len);
+	if (len < needed) {
+		param->flags |= DM_BUFFER_FULL_FLAG;
+		goto out;
+	}
+	param->data_size = param->data_start + needed;
+
+	nl->dev = 0;	/* Flags no data */
+
+	/*
+	 * Now loop through filling out the names.
+	 */
+	for (i = 0; i < NUM_BUCKETS; i++) {
+		list_for_each_entry (hc, _name_buckets + i, name_list) {
+			if (old_nl)
+				old_nl->next = (uint32_t) ((void *) nl -
+							   (void *) old_nl);
+			disk = dm_disk(hc->md);
+			nl->dev = MKDEV(disk->major, disk->first_minor);
+			nl->next = 0;
+			strcpy(nl->name, hc->name);
+
+			old_nl = nl;
+			nl = align_ptr(((void *) ++nl) + strlen(hc->name) + 1);
+		}
+	}
+
+ out:
+	up_write(&_hash_lock);
+	return 0;
+}
+
+static int check_name(const char *name)
+{
+	if (strchr(name, '/')) {
+		DMWARN("invalid device name");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Fills in a dm_ioctl structure, ready for sending back to
+ * userland.
+ */
+static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
+{
+	struct gendisk *disk = dm_disk(md);
+	struct dm_table *table;
+	struct block_device *bdev;
+
+	param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
+			  DM_ACTIVE_PRESENT_FLAG);
+
+	if (dm_suspended(md))
+		param->flags |= DM_SUSPEND_FLAG;
+
+	bdev = bdget_disk(disk, 0);
+	if (!bdev)
+		return -ENXIO;
+
+	param->dev = MKDEV(disk->major, disk->first_minor);
+
+	/*
+	 * Yes, this will be out of date by the time it gets back
+	 * to userland, but it is still very useful ofr
+	 * debugging.
+	 */
+	param->open_count = bdev->bd_openers;
+	bdput(bdev);
+
+	if (disk->policy)
+		param->flags |= DM_READONLY_FLAG;
+
+	param->event_nr = dm_get_event_nr(md);
+
+	table = dm_get_table(md);
+	if (table) {
+		param->flags |= DM_ACTIVE_PRESENT_FLAG;
+		param->target_count = dm_table_get_num_targets(table);
+		dm_table_put(table);
+	} else
+		param->target_count = 0;
+
+	return 0;
+}
+
+static int dev_create(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	struct mapped_device *md;
+
+	r = check_name(param->name);
+	if (r)
+		return r;
+
+	if (param->flags & DM_PERSISTENT_DEV_FLAG)
+		r = dm_create_with_minor(minor(to_kdev_t(param->dev)), &md);
+	else
+		r = dm_create(&md);
+
+	if (r)
+		return r;
+
+	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
+	if (r) {
+		dm_put(md);
+		return r;
+	}
+
+	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+	r = __dev_status(md, param);
+	dm_put(md);
+
+	return r;
+}
+
+/*
+ * Always use UUID for lookups if it's present, otherwise use name.
+ */
+static inline struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
+{
+	return *param->uuid ?
+	    __get_uuid_cell(param->uuid) : __get_name_cell(param->name);
+}
+
+static inline struct mapped_device *find_device(struct dm_ioctl *param)
+{
+	struct hash_cell *hc;
+	struct mapped_device *md = NULL;
+
+	down_read(&_hash_lock);
+	hc = __find_device_hash_cell(param);
+	if (hc) {
+		md = hc->md;
+
+		/*
+		 * Sneakily write in both the name and the uuid
+		 * while we have the cell.
+		 */
+		strncpy(param->name, hc->name, sizeof(param->name));
+		if (hc->uuid)
+			strncpy(param->uuid, hc->uuid, sizeof(param->uuid)-1);
+		else
+			param->uuid[0] = '\0';
+
+		if (hc->new_map)
+			param->flags |= DM_INACTIVE_PRESENT_FLAG;
+		else
+			param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+		dm_get(md);
+	}
+	up_read(&_hash_lock);
+
+	return md;
+}
+
+static int dev_remove(struct dm_ioctl *param, size_t param_size)
+{
+	struct hash_cell *hc;
+
+	down_write(&_hash_lock);
+	hc = __find_device_hash_cell(param);
+
+	if (!hc) {
+		DMWARN("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	__hash_remove(hc);
+	up_write(&_hash_lock);
+	param->data_size = 0;
+	return 0;
+}
+
+/*
+ * Check a string doesn't overrun the chunk of
+ * memory we copied from userland.
+ */
+static int invalid_str(char *str, void *end)
+{
+	while ((void *) str < end)
+		if (!*str++)
+			return 0;
+
+	return -EINVAL;
+}
+
+static int dev_rename(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	char *new_name = (char *) param + param->data_start;
+
+	if (new_name < (char *) (param + 1) ||
+	    invalid_str(new_name, (void *) param + param_size)) {
+		DMWARN("Invalid new logical volume name supplied.");
+		return -EINVAL;
+	}
+
+	r = check_name(new_name);
+	if (r)
+		return r;
+
+	param->data_size = 0;
+	return dm_hash_rename(param->name, new_name);
+}
+
+static int suspend(struct dm_ioctl *param)
+{
+	int r = 0;
+	struct mapped_device *md;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	if (!dm_suspended(md))
+		r = dm_suspend(md);
+
+	if (!r)
+		r = __dev_status(md, param);
+
+	dm_put(md);
+	return r;
+}
+
+static int resume(struct dm_ioctl *param)
+{
+	int r = 0;
+	struct hash_cell *hc;
+	struct mapped_device *md;
+	struct dm_table *new_map;
+
+	down_write(&_hash_lock);
+
+	hc = __find_device_hash_cell(param);
+	if (!hc) {
+		DMWARN("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	md = hc->md;
+	dm_get(md);
+
+	new_map = hc->new_map;
+	hc->new_map = NULL;
+	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+	up_write(&_hash_lock);
+
+	/* Do we need to load a new map ? */
+	if (new_map) {
+		/* Suspend if it isn't already suspended */
+		if (!dm_suspended(md))
+			dm_suspend(md);
+
+		r = dm_swap_table(md, new_map);
+		if (r) {
+			dm_put(md);
+			dm_table_put(new_map);
+			return r;
+		}
+
+		if (dm_table_get_mode(new_map) & FMODE_WRITE)
+			set_disk_ro(dm_disk(md), 0);
+		else
+			set_disk_ro(dm_disk(md), 1);
+
+		dm_table_put(new_map);
+	}
+
+	if (dm_suspended(md))
+		r = dm_resume(md);
+
+	if (!r)
+		r = __dev_status(md, param);
+
+	dm_put(md);
+	return r;
+}
+
+/*
+ * Set or unset the suspension state of a device.
+ * If the device already is in the requested state we just return its status.
+ */
+static int dev_suspend(struct dm_ioctl *param, size_t param_size)
+{
+	if (param->flags & DM_SUSPEND_FLAG)
+		return suspend(param);
+
+	return resume(param);
+}
+
+/*
+ * Copies device info back to user space, used by
+ * the create and info ioctls.
+ */
+static int dev_status(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	struct mapped_device *md;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	r = __dev_status(md, param);
+	dm_put(md);
+	return r;
+}
+
+/*
+ * Wait for a device to report an event
+ */
+static int dev_wait(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	struct mapped_device *md;
+	DECLARE_WAITQUEUE(wq, current);
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	/*
+	 * Wait for a notification event
+	 */
+	set_current_state(TASK_INTERRUPTIBLE);
+	if (!dm_add_wait_queue(md, &wq, param->event_nr)) {
+		schedule();
+		dm_remove_wait_queue(md, &wq);
+	}
+ 	set_current_state(TASK_RUNNING);
+
+	/*
+	 * The userland program is going to want to know what
+	 * changed to trigger the event, so we may as well tell
+	 * him and save an ioctl.
+	 */
+	r = __dev_status(md, param);
+
+	dm_put(md);
+	return r;
+}
+
+static inline int get_mode(struct dm_ioctl *param)
+{
+	int mode = FMODE_READ | FMODE_WRITE;
+
+	if (param->flags & DM_READONLY_FLAG)
+		mode = FMODE_READ;
+
+	return mode;
+}
+
+static int next_target(struct dm_target_spec *last, uint32_t next, void *end,
+		       struct dm_target_spec **spec, char **target_params)
+{
+	*spec = (struct dm_target_spec *) ((unsigned char *) last + next);
+	*target_params = (char *) (*spec + 1);
+
+	if (*spec < (last + 1))
+		return -EINVAL;
+
+	return invalid_str(*target_params, end);
+}
+
+static int populate_table(struct dm_table *table,
+			  struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	unsigned int i = 0;
+	struct dm_target_spec *spec = (struct dm_target_spec *) param;
+	uint32_t next = param->data_start;
+	void *end = (void *) param + param_size;
+	char *target_params;
+
+	if (!param->target_count) {
+		DMWARN("populate_table: no targets specified");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < param->target_count; i++) {
+
+		r = next_target(spec, next, end, &spec, &target_params);
+		if (r) {
+			DMWARN("unable to find target");
+			return r;
+		}
+
+		r = dm_table_add_target(table, spec->target_type,
+					(sector_t) spec->sector_start,
+					(sector_t) spec->length,
+					target_params);
+		if (r) {
+			DMWARN("error adding target to table");
+			return r;
+		}
+
+		next = spec->next;
+	}
+
+	return dm_table_complete(table);
+}
+
+static int table_load(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	struct hash_cell *hc;
+	struct dm_table *t;
+
+	r = dm_table_create(&t, get_mode(param));
+	if (r)
+		return r;
+
+	r = populate_table(t, param, param_size);
+	if (r) {
+		dm_table_put(t);
+		return r;
+	}
+
+	down_write(&_hash_lock);
+	hc = __find_device_hash_cell(param);
+	if (!hc) {
+		DMWARN("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	hc->new_map = t;
+	param->flags |= DM_INACTIVE_PRESENT_FLAG;
+
+	r = __dev_status(hc->md, param);
+	up_write(&_hash_lock);
+	return r;
+}
+
+static int table_clear(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	struct hash_cell *hc;
+
+	down_write(&_hash_lock);
+
+	hc = __find_device_hash_cell(param);
+	if (!hc) {
+		DMWARN("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	if (hc->new_map) {
+		dm_table_put(hc->new_map);
+		hc->new_map = NULL;
+	}
+
+	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+	r = __dev_status(hc->md, param);
+	up_write(&_hash_lock);
+	return r;
+}
+
+/*
+ * Retrieves a list of devices used by a particular dm device.
+ */
+static void retrieve_deps(struct dm_table *table,
+			  struct dm_ioctl *param, size_t param_size)
+{
+	unsigned int count = 0;
+	struct list_head *tmp;
+	size_t len, needed;
+	struct dm_target_deps *deps;
+
+	deps = get_result_buffer(param, param_size, &len);
+
+	/*
+	 * Count the devices.
+	 */
+	list_for_each(tmp, dm_table_get_devices(table))
+		count++;
+
+	/*
+	 * Check we have enough space.
+	 */
+	needed = sizeof(*deps) + (sizeof(*deps->dev) * count);
+	if (len < needed) {
+		param->flags |= DM_BUFFER_FULL_FLAG;
+		return;
+	}
+
+	/*
+	 * Fill in the devices.
+	 */
+	deps->count = count;
+	count = 0;
+	list_for_each(tmp, dm_table_get_devices(table)) {
+		struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
+		deps->dev[count++] = dd->bdev->bd_dev;
+	}
+
+	param->data_size = param->data_start + needed;
+}
+
+static int table_deps(struct dm_ioctl *param, size_t param_size)
+{
+	int r = 0;
+	struct mapped_device *md;
+	struct dm_table *table;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	r = __dev_status(md, param);
+	if (r)
+		goto out;
+
+	table = dm_get_table(md);
+	if (table) {
+		retrieve_deps(table, param, param_size);
+		dm_table_put(table);
+	}
+
+ out:
+	dm_put(md);
+	return r;
+}
+
+/*
+ * Build up the status struct for each target
+ */
+static void retrieve_status(struct dm_table *table,
+			    struct dm_ioctl *param, size_t param_size)
+{
+	unsigned int i, num_targets;
+	struct dm_target_spec *spec;
+	char *outbuf, *outptr;
+	status_type_t type;
+	size_t remaining, len, used = 0;
+
+	outptr = outbuf = get_result_buffer(param, param_size, &len);
+
+	if (param->flags & DM_STATUS_TABLE_FLAG)
+		type = STATUSTYPE_TABLE;
+	else
+		type = STATUSTYPE_INFO;
+
+	/* Get all the target info */
+	num_targets = dm_table_get_num_targets(table);
+	for (i = 0; i < num_targets; i++) {
+		struct dm_target *ti = dm_table_get_target(table, i);
+
+		remaining = len - (outptr - outbuf);
+		if (remaining < sizeof(struct dm_target_spec)) {
+			param->flags |= DM_BUFFER_FULL_FLAG;
+			break;
+		}
+
+		spec = (struct dm_target_spec *) outptr;
+
+		spec->status = 0;
+		spec->sector_start = ti->begin;
+		spec->length = ti->len;
+		strncpy(spec->target_type, ti->type->name,
+			sizeof(spec->target_type));
+
+		outptr += sizeof(struct dm_target_spec);
+		remaining = len - (outptr - outbuf);
+
+		/* Get the status/table string from the target driver */
+		if (ti->type->status) {
+			if (ti->type->status(ti, type, outptr, remaining)) {
+				param->flags |= DM_BUFFER_FULL_FLAG;
+				break;
+			}
+		} else
+			outptr[0] = '\0';
+
+		outptr += strlen(outptr) + 1;
+		used = param->data_start + (outptr - outbuf);
+
+		align_ptr(outptr);
+		spec->next = outptr - outbuf;
+	}
+
+	if (used)
+		param->data_size = used;
+
+	param->target_count = num_targets;
+}
+
+/*
+ * Return the status of a device as a text string for each
+ * target.
+ */
+static int table_status(struct dm_ioctl *param, size_t param_size)
+{
+	int r;
+	struct mapped_device *md;
+	struct dm_table *table;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	r = __dev_status(md, param);
+	if (r)
+		goto out;
+
+	table = dm_get_table(md);
+	if (table) {
+		retrieve_status(table, param, param_size);
+		dm_table_put(table);
+	}
+
+ out:
+	dm_put(md);
+	return r;
+}
+
+/*-----------------------------------------------------------------
+ * Implementation of open/close/ioctl on the special char
+ * device.
+ *---------------------------------------------------------------*/
+static ioctl_fn lookup_ioctl(unsigned int cmd)
+{
+	static struct {
+		int cmd;
+		ioctl_fn fn;
+	} _ioctls[] = {
+		{DM_VERSION_CMD, NULL},	/* version is dealt with elsewhere */
+		{DM_REMOVE_ALL_CMD, remove_all},
+		{DM_LIST_DEVICES_CMD, list_devices},
+
+		{DM_DEV_CREATE_CMD, dev_create},
+		{DM_DEV_REMOVE_CMD, dev_remove},
+		{DM_DEV_RENAME_CMD, dev_rename},
+		{DM_DEV_SUSPEND_CMD, dev_suspend},
+		{DM_DEV_STATUS_CMD, dev_status},
+		{DM_DEV_WAIT_CMD, dev_wait},
+
+		{DM_TABLE_LOAD_CMD, table_load},
+		{DM_TABLE_CLEAR_CMD, table_clear},
+		{DM_TABLE_DEPS_CMD, table_deps},
+		{DM_TABLE_STATUS_CMD, table_status}
+	};
+
+	return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
+}
+
+/*
+ * As well as checking the version compatibility this always
+ * copies the kernel interface version out.
+ */
+static int check_version(unsigned int cmd, struct dm_ioctl *user)
+{
+	uint32_t version[3];
+	int r = 0;
+
+	if (copy_from_user(version, user->version, sizeof(version)))
+		return -EFAULT;
+
+	if ((DM_VERSION_MAJOR != version[0]) ||
+	    (DM_VERSION_MINOR < version[1])) {
+		DMWARN("ioctl interface mismatch: "
+		       "kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
+		       DM_VERSION_MAJOR, DM_VERSION_MINOR,
+		       DM_VERSION_PATCHLEVEL,
+		       version[0], version[1], version[2], cmd);
+		r = -EINVAL;
+	}
+
+	/*
+	 * Fill in the kernel version.
+	 */
+	version[0] = DM_VERSION_MAJOR;
+	version[1] = DM_VERSION_MINOR;
+	version[2] = DM_VERSION_PATCHLEVEL;
+	if (copy_to_user(user->version, version, sizeof(version)))
+		return -EFAULT;
+
+	return r;
+}
+
+static void free_params(struct dm_ioctl *param)
+{
+	vfree(param);
+}
+
+static int copy_params(struct dm_ioctl *user, struct dm_ioctl **param)
+{
+	struct dm_ioctl tmp, *dmi;
+
+	if (copy_from_user(&tmp, user, sizeof(tmp)))
+		return -EFAULT;
+
+	if (tmp.data_size < sizeof(tmp))
+		return -EINVAL;
+
+	dmi = (struct dm_ioctl *) vmalloc(tmp.data_size);
+	if (!dmi)
+		return -ENOMEM;
+
+	if (copy_from_user(dmi, user, tmp.data_size)) {
+		vfree(dmi);
+		return -EFAULT;
+	}
+
+	*param = dmi;
+	return 0;
+}
+
+static int validate_params(uint cmd, struct dm_ioctl *param)
+{
+	/* Always clear this flag */
+	param->flags &= ~DM_BUFFER_FULL_FLAG;
+
+	/* Ignores parameters */
+	if (cmd == DM_REMOVE_ALL_CMD || cmd == DM_LIST_DEVICES_CMD)
+		return 0;
+
+	/* Unless creating, either name or uuid but not both */
+	if (cmd != DM_DEV_CREATE_CMD) {
+		if ((!*param->uuid && !*param->name) ||
+		    (*param->uuid && *param->name)) {
+			DMWARN("one of name or uuid must be supplied, cmd(%u)",
+			       cmd);
+			return -EINVAL;
+		}
+	}
+
+	/* Ensure strings are terminated */
+	param->name[DM_NAME_LEN - 1] = '\0';
+	param->uuid[DM_UUID_LEN - 1] = '\0';
+
+	return 0;
+}
+
+static int ctl_ioctl(struct inode *inode, struct file *file,
+		     uint command, ulong u)
+{
+	int r = 0;
+	unsigned int cmd;
+	struct dm_ioctl *param;
+	struct dm_ioctl *user = (struct dm_ioctl *) u;
+	ioctl_fn fn = NULL;
+	size_t param_size;
+
+	/* only root can play with this */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (_IOC_TYPE(command) != DM_IOCTL)
+		return -ENOTTY;
+
+	cmd = _IOC_NR(command);
+
+	/*
+	 * Check the interface version passed in.  This also
+	 * writes out the kernel's interface version.
+	 */
+	r = check_version(cmd, user);
+	if (r)
+		return r;
+
+	/*
+	 * Nothing more to do for the version command.
+	 */
+	if (cmd == DM_VERSION_CMD)
+		return 0;
+
+	fn = lookup_ioctl(cmd);
+	if (!fn) {
+		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
+		return -ENOTTY;
+	}
+
+	/*
+	 * Trying to avoid low memory issues when a device is
+	 * suspended.
+	 */
+	current->flags |= PF_MEMALLOC;
+
+	/*
+	 * Copy the parameters into kernel space.
+	 */
+	r = copy_params(user, &param);
+	if (r) {
+		current->flags &= ~PF_MEMALLOC;
+		return r;
+	}
+
+	/*
+	 * FIXME: eventually we will remove the PF_MEMALLOC flag
+	 * here.  However the tools still do nasty things like
+	 * 'load' while a device is suspended.
+	 */
+
+	r = validate_params(cmd, param);
+	if (r)
+		goto out;
+
+	param_size = param->data_size;
+	param->data_size = sizeof(*param);
+	r = fn(param, param_size);
+
+	/*
+	 * Copy the results back to userland.
+	 */
+	if (!r && copy_to_user(user, param, param->data_size))
+		r = -EFAULT;
+
+ out:
+	free_params(param);
+	current->flags &= ~PF_MEMALLOC;
+	return r;
+}
+
+static struct file_operations _ctl_fops = {
+	.ioctl	 = ctl_ioctl,
+	.owner	 = THIS_MODULE,
+};
+
+static struct miscdevice _dm_misc = {
+	.minor 		= MISC_DYNAMIC_MINOR,
+	.name  		= DM_NAME,
+	.devfs_name 	= "mapper/control",
+	.fops  		= &_ctl_fops
+};
+
+/*
+ * Create misc character device and link to DM_DIR/control.
+ */
+int __init dm_interface_init(void)
+{
+	int r;
+
+	r = dm_hash_init();
+	if (r)
+		return r;
+
+	r = misc_register(&_dm_misc);
+	if (r) {
+		DMERR("misc_register failed for control device");
+		dm_hash_exit();
+		return r;
+	}
+
+	DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
+	       DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
+	       DM_DRIVER_EMAIL);
+	return 0;
+}
+
+void dm_interface_exit(void)
+{
+	if (misc_deregister(&_dm_misc) < 0)
+		DMERR("misc_deregister failed for control device");
+
+	dm_hash_exit();
+}

drivers/md/dm-ioctl.c

 /*
- * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ * Copyright (C) 2003 Sistina Software (UK) Limited.
  *
  * This file is released under the GPL.
  */
 
-#include "dm.h"
-
-#include <linux/module.h>
-#include <linux/vmalloc.h>
-#include <linux/miscdevice.h>
 #include <linux/dm-ioctl.h>
-#include <linux/init.h>
-#include <linux/wait.h>
-#include <linux/slab.h>
-#include <linux/devfs_fs_kernel.h>
-
-#include <asm/uaccess.h>
-
-#define DM_DRIVER_EMAIL "dm@uk.sistina.com"
-
-/*-----------------------------------------------------------------
- * The ioctl interface needs to be able to look up devices by
- * name or uuid.
- *---------------------------------------------------------------*/
-struct hash_cell {
-	struct list_head name_list;
-	struct list_head uuid_list;
-
-	char *name;
-	char *uuid;
-	struct mapped_device *md;
-};
-
-#define NUM_BUCKETS 64
-#define MASK_BUCKETS (NUM_BUCKETS - 1)
-static struct list_head _name_buckets[NUM_BUCKETS];
-static struct list_head _uuid_buckets[NUM_BUCKETS];
-
-void dm_hash_remove_all(void);
-
-/*
- * Guards access to all three tables.
- */
-static DECLARE_RWSEM(_hash_lock);
-
-static void init_buckets(struct list_head *buckets)
-{
-	unsigned int i;
-
-	for (i = 0; i < NUM_BUCKETS; i++)
-		INIT_LIST_HEAD(buckets + i);
-}
-
-int dm_hash_init(void)
-{
-	init_buckets(_name_buckets);
-	init_buckets(_uuid_buckets);
-	devfs_mk_dir(DM_DIR);
-	return 0;
-}
-
-void dm_hash_exit(void)
-{
-	dm_hash_remove_all();
-	devfs_remove(DM_DIR);
-}
-
-/*-----------------------------------------------------------------
- * Hash function:
- * We're not really concerned with the str hash function being
- * fast since it's only used by the ioctl interface.
- *---------------------------------------------------------------*/
-static unsigned int hash_str(const char *str)
-{
-	const unsigned int hash_mult = 2654435387U;
-	unsigned int h = 0;
-
-	while (*str)
-		h = (h + (unsigned int) *str++) * hash_mult;
-
-	return h & MASK_BUCKETS;
-}
-
-/*-----------------------------------------------------------------
- * Code for looking up a device by name
- *---------------------------------------------------------------*/
-static struct hash_cell *__get_name_cell(const char *str)
-{
-	struct list_head *tmp;
-	struct hash_cell *hc;
-	unsigned int h = hash_str(str);
-
-	list_for_each (tmp, _name_buckets + h) {
-		hc = list_entry(tmp, struct hash_cell, name_list);
-		if (!strcmp(hc->name, str))
-			return hc;
-	}
-
-	return NULL;
-}
-
-static struct hash_cell *__get_uuid_cell(const char *str)
-{
-	struct list_head *tmp;
-	struct hash_cell *hc;
-	unsigned int h = hash_str(str);
-
-	list_for_each (tmp, _uuid_buckets + h) {
-		hc = list_entry(tmp, struct hash_cell, uuid_list);
-		if (!strcmp(hc->uuid, str))
-			return hc;
-	}
-
-	return NULL;
-}
-
-/*-----------------------------------------------------------------
- * Inserting, removing and renaming a device.
- *---------------------------------------------------------------*/
-static inline char *kstrdup(const char *str)
-{
-	char *r = kmalloc(strlen(str) + 1, GFP_KERNEL);
-	if (r)
-		strcpy(r, str);
-	return r;
-}
-
-static struct hash_cell *alloc_cell(const char *name, const char *uuid,
-				    struct mapped_device *md)
-{
-	struct hash_cell *hc;
-
-	hc = kmalloc(sizeof(*hc), GFP_KERNEL);
-	if (!hc)
-		return NULL;
-
-	hc->name = kstrdup(name);
-	if (!hc->name) {
-		kfree(hc);
-		return NULL;
-	}
-
-	if (!uuid)
-		hc->uuid = NULL;
-
-	else {
-		hc->uuid = kstrdup(uuid);
-		if (!hc->uuid) {
-			kfree(hc->name);
-			kfree(hc);
-			return NULL;
-		}
-	}
-
-	INIT_LIST_HEAD(&hc->name_list);
-	INIT_LIST_HEAD(&hc->uuid_list);
-	hc->md = md;
-	return hc;
-}
-
-static void free_cell(struct hash_cell *hc)
-{
-	if (hc) {
-		kfree(hc->name);
-		kfree(hc->uuid);
-		kfree(hc);
-	}
-}
-
-/*
- * devfs stuff.
- */
-static int register_with_devfs(struct hash_cell *hc)
-{
-	struct gendisk *disk = dm_disk(hc->md);
-
-	devfs_mk_bdev(MKDEV(disk->major, disk->first_minor),
-		       S_IFBLK | S_IRUSR | S_IWUSR | S_IRGRP,
-		       DM_DIR "/%s", hc->name);
-	return 0;
-}
-
-static int unregister_with_devfs(struct hash_cell *hc)
-{
-	devfs_remove(DM_DIR"/%s", hc->name);
-	return 0;
-}
-
-/*
- * The kdev_t and uuid of a device can never change once it is
- * initially inserted.
- */
-int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
-{
-	struct hash_cell *cell;
-
-	/*
-	 * Allocate the new cells.
-	 */
-	cell = alloc_cell(name, uuid, md);
-	if (!cell)
-		return -ENOMEM;
-
-	/*
-	 * Insert the cell into all three hash tables.
-	 */
-	down_write(&_hash_lock);
-	if (__get_name_cell(name))
-		goto bad;
-
-	list_add(&cell->name_list, _name_buckets + hash_str(name));
-
-	if (uuid) {
-		if (__get_uuid_cell(uuid)) {
-			list_del(&cell->name_list);
-			goto bad;
-		}
-		list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
-	}
-	register_with_devfs(cell);
-	dm_get(md);
-	up_write(&_hash_lock);
-
-	return 0;
-
- bad:
-	up_write(&_hash_lock);
-	free_cell(cell);
-	return -EBUSY;
-}
-
-void __hash_remove(struct hash_cell *hc)
-{
-	/* remove from the dev hash */
-	list_del(&hc->uuid_list);
-	list_del(&hc->name_list);
-	unregister_with_devfs(hc);
-	dm_put(hc->md);
-	free_cell(hc);
-}
-
-void dm_hash_remove_all(void)
-{
-	int i;
-	struct hash_cell *hc;
-	struct list_head *tmp, *n;
-
-	down_write(&_hash_lock);
-	for (i = 0; i < NUM_BUCKETS; i++) {
-		list_for_each_safe (tmp, n, _name_buckets + i) {
-			hc = list_entry(tmp, struct hash_cell, name_list);
-			__hash_remove(hc);
-		}
-	}
-	up_write(&_hash_lock);
-}
-
-int dm_hash_rename(const char *old, const char *new)
-{
-	char *new_name, *old_name;
-	struct hash_cell *hc;
-
-	/*
-	 * duplicate new.
-	 */
-	new_name = kstrdup(new);
-	if (!new_name)
-		return -ENOMEM;
-
-	down_write(&_hash_lock);
-
-	/*
-	 * Is new free ?
-	 */
-	hc = __get_name_cell(new);
-	if (hc) {
-		DMWARN("asked to rename to an already existing name %s -> %s",
-		       old, new);
-		up_write(&_hash_lock);
-		kfree(new_name);
-		return -EBUSY;
-	}
-
-	/*
-	 * Is there such a device as 'old' ?
-	 */
-	hc = __get_name_cell(old);
-	if (!hc) {
-		DMWARN("asked to rename a non existent device %s -> %s",
-		       old, new);
-		up_write(&_hash_lock);
-		kfree(new_name);
-		return -ENXIO;
-	}
-
-	/*
-	 * rename and move the name cell.
-	 */
-	unregister_with_devfs(hc);
-
-	list_del(&hc->name_list);
-	old_name = hc->name;
-	hc->name = new_name;
-	list_add(&hc->name_list, _name_buckets + hash_str(new_name));
-
-	/* rename the device node in devfs */
-	register_with_devfs(hc);
-
-	up_write(&_hash_lock);
-	kfree(old_name);
-	return 0;
-}
-
-
-/*-----------------------------------------------------------------
- * Implementation of the ioctl commands
- *---------------------------------------------------------------*/
-
-/*
- * All the ioctl commands get dispatched to functions with this
- * prototype.
- */
-typedef int (*ioctl_fn)(struct dm_ioctl *param, struct dm_ioctl *user);
-
-/*
- * Check a string doesn't overrun the chunk of
- * memory we copied from userland.
- */
-static int valid_str(char *str, void *begin, void *end)
-{
-	while (((void *) str >= begin) && ((void *) str < end))
-		if (!*str++)
-			return 0;
-
-	return -EINVAL;
-}
-
-static int next_target(struct dm_target_spec *last, uint32_t next,
-		       void *begin, void *end,
-		       struct dm_target_spec **spec, char **params)
-{
-	*spec = (struct dm_target_spec *)
-	    ((unsigned char *) last + next);
-	*params = (char *) (*spec + 1);
-
-	if (*spec < (last + 1) || ((void *) *spec > end))
-		return -EINVAL;
-
-	return valid_str(*params, begin, end);
-}
-
-static int populate_table(struct dm_table *table, struct dm_ioctl *args)
-{
-	int r, first = 1;
-	unsigned int i = 0;
-	struct dm_target_spec *spec;
-	char *params;
-	void *begin, *end;
-
-	if (!args->target_count) {
-		DMWARN("populate_table: no targets specified");
-		return -EINVAL;
-	}
-
-	begin = (void *) args;
-	end = begin + args->data_size;
-
-	for (i = 0; i < args->target_count; i++) {
-
-		if (first)
-			r = next_target((struct dm_target_spec *) args,
-					args->data_start,
-					begin, end, &spec, &params);
-		else
-			r = next_target(spec, spec->next, begin, end,
-					&spec, &params);
-
-		if (r) {
-			DMWARN("unable to find target");
-			return -EINVAL;
-		}
-
-		r = dm_table_add_target(table, spec->target_type,
-					(sector_t) spec->sector_start,
-					(sector_t) spec->length,
-					params);
-		if (r) {
-			DMWARN("internal error adding target to table");
-			return -EINVAL;
-		}
-
-		first = 0;
-	}
-
-	return dm_table_complete(table);
-}
-
-/*
- * Round up the ptr to the next 'align' boundary.  Obviously
- * 'align' must be a power of 2.
- */
-static inline void *align_ptr(void *ptr, unsigned int align)
-{
-	align--;
-	return (void *) (((unsigned long) (ptr + align)) & ~align);
-}
-
-/*
- * Copies a dm_ioctl and an optional additional payload to
- * userland.
- */
-static int results_to_user(struct dm_ioctl *user, struct dm_ioctl *param,
-			   void *data, uint32_t len)
-{
-	int r;
-	void *ptr = NULL;
-
-	if (data) {
-		ptr = align_ptr(user + 1, sizeof(unsigned long));
-		param->data_start = ptr - (void *) user;
-	}
-
-	/*
-	 * The version number has already been filled in, so we
-	 * just copy later fields.
-	 */
-	r = copy_to_user(&user->data_size, &param->data_size,
-			 sizeof(*param) - sizeof(param->version));
-	if (r)
-		return -EFAULT;
-
-	if (data) {
-		if (param->data_start + len > param->data_size)
-			return -ENOSPC;
-
-		if (copy_to_user(ptr, data, len))
-			r = -EFAULT;
-	}
-
-	return r;
-}
-
-/*
- * Fills in a dm_ioctl structure, ready for sending back to
- * userland.
- */
-static int __info(struct mapped_device *md, struct dm_ioctl *param)
-{
-	struct dm_table *table;
-	struct block_device *bdev;
-	struct gendisk *disk = dm_disk(md);
-
-	param->flags = DM_EXISTS_FLAG;
-	if (dm_suspended(md))
-		param->flags |= DM_SUSPEND_FLAG;
-
-	bdev = bdget_disk(disk, 0);
-	if (!bdev)
-		return -ENXIO;
-
-	param->dev = bdev->bd_dev;
-	param->open_count = bdev->bd_openers;
-	bdput(bdev);
-
-	if (disk->policy)
-		param->flags |= DM_READONLY_FLAG;
-
-	table = dm_get_table(md);
-	param->target_count = dm_table_get_num_targets(table);
-	dm_table_put(table);
-
-	return 0;
-}
-
-/*
- * Always use UUID for lookups if it's present, otherwise use name.
- */
-static inline struct mapped_device *find_device(struct dm_ioctl *param)
-{
-	struct hash_cell *hc;
-	struct mapped_device *md = NULL;
-
-	down_read(&_hash_lock);
-	hc = *param->uuid ? __get_uuid_cell(param->uuid) :
-		__get_name_cell(param->name);
-	if (hc) {
-		md = hc->md;
-
-		/*
-		 * Sneakily write in both the name and the uuid
-		 * while we have the cell.
-		 */
-		strlcpy(param->name, hc->name, sizeof(param->name));
-		if (hc->uuid)
-			strlcpy(param->uuid, hc->uuid, sizeof(param->uuid));
-		else
-			param->uuid[0] = '\0';
-
-		dm_get(md);
-	}
-	up_read(&_hash_lock);
-
-	return md;
-}
-
-#define ALIGNMENT sizeof(int)
-static void *_align(void *ptr, unsigned int a)
-{
-	register unsigned long align = --a;
-
-	return (void *) (((unsigned long) ptr + align) & ~align);
-}
-
-/*
- * Copies device info back to user space, used by
- * the create and info ioctls.
- */
-static int info(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	struct mapped_device *md;
-
-	param->flags = 0;
-
-	md = find_device(param);
-	if (!md)
-		/*
-		 * Device not found - returns cleared exists flag.
-		 */
-		goto out;
-
-	__info(md, param);
-	dm_put(md);
-
-      out:
-	return results_to_user(user, param, NULL, 0);
-}
-
-static inline int get_mode(struct dm_ioctl *param)
-{
-	int mode = FMODE_READ | FMODE_WRITE;
-
-	if (param->flags & DM_READONLY_FLAG)
-		mode = FMODE_READ;
-
-	return mode;
-}
-
-static int check_name(const char *name)
-{
-	if (name[0] == '/') {
-		DMWARN("invalid device name");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-static int create(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	int r;
-	struct dm_table *t;
-	struct mapped_device *md;
-
-	r = check_name(param->name);
-	if (r)
-		return r;
-
-	r = dm_table_create(&t, get_mode(param));
-	if (r)
-		return r;
-
-	r = populate_table(t, param);
-	if (r) {
-		dm_table_put(t);
-		return r;
-	}
-
-	if (param->flags & DM_PERSISTENT_DEV_FLAG)
-		r = dm_create_with_minor(minor(to_kdev_t(param->dev)), t, &md);
-	else
-		r = dm_create(t, &md);
-
-	if (r) {
-		dm_table_put(t);
-		return r;
-	}
-	dm_table_put(t);	/* md will have grabbed its own reference */
-
-	set_disk_ro(dm_disk(md), (param->flags & DM_READONLY_FLAG) ? 1 : 0);
-	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
-	dm_put(md);
-
-	return r ? r : info(param, user);
-}
-
-/*
- * Build up the status struct for each target
- */
-static int __status(struct mapped_device *md, struct dm_ioctl *param,
-		    char *outbuf, size_t *len)
-{
-	unsigned int i, num_targets;
-	struct dm_target_spec *spec;
-	char *outptr;
-	status_type_t type;
-	struct dm_table *table = dm_get_table(md);
-
-	if (param->flags & DM_STATUS_TABLE_FLAG)
-		type = STATUSTYPE_TABLE;
-	else
-		type = STATUSTYPE_INFO;
-
-	outptr = outbuf;
-
-	/* Get all the target info */
-	num_targets = dm_table_get_num_targets(table);
-	for (i = 0; i < num_targets; i++) {
-		struct dm_target *ti = dm_table_get_target(table, i);
-
-		if (outptr - outbuf +
-		    sizeof(struct dm_target_spec) > param->data_size) {
-			dm_table_put(table);
-			return -ENOMEM;
-		}
-
-		spec = (struct dm_target_spec *) outptr;
-
-		spec->status = 0;
-		spec->sector_start = ti->begin;
-		spec->length = ti->len;
-		strlcpy(spec->target_type, ti->type->name,
-			sizeof(spec->target_type));
-
-		outptr += sizeof(struct dm_target_spec);
-
-		/* Get the status/table string from the target driver */
-		if (ti->type->status)
-			ti->type->status(ti, type, outptr,
-					 outbuf + param->data_size - outptr);
-		else
-			outptr[0] = '\0';
-
-		outptr += strlen(outptr) + 1;
-		_align(outptr, ALIGNMENT);
-		spec->next = outptr - outbuf;
-	}
-
-	param->target_count = num_targets;
-	*len = outptr - outbuf;
-	dm_table_put(table);
-
-	return 0;
-}
-
-/*
- * Return the status of a device as a text string for each
- * target.
- */
-static int get_status(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	struct mapped_device *md;
-	size_t len = 0;
-	int ret;
-	char *outbuf = NULL;
-
-	md = find_device(param);
-	if (!md)
-		/*
-		 * Device not found - returns cleared exists flag.
-		 */
-		goto out;
-
-	/* We haven't a clue how long the resultant data will be so
-	   just allocate as much as userland has allowed us and make sure
-	   we don't overun it */
-	outbuf = kmalloc(param->data_size, GFP_KERNEL);
-	if (!outbuf)
-		goto out;
-	/*
-	 * Get the status of all targets
-	 */
-	__status(md, param, outbuf, &len);
-
-	/*
-	 * Setup the basic dm_ioctl structure.
-	 */
-	__info(md, param);
-
-      out:
-	if (md)
-		dm_put(md);
-
-	ret = results_to_user(user, param, outbuf, len);
-
-	if (outbuf)
-		kfree(outbuf);
-
-	return ret;
-}
-
-/*
- * Wait for a device to report an event
- */
-static int wait_device_event(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	struct mapped_device *md;
-	DECLARE_WAITQUEUE(wq, current);
-
-	md = find_device(param);
-	if (!md)
-		/*
-		 * Device not found - returns cleared exists flag.
-		 */
-		goto out;
-
-	/*
-	 * Setup the basic dm_ioctl structure.
-	 */
-	__info(md, param);
-
-	/*
-	 * Wait for a notification event
-	 */
-	set_current_state(TASK_INTERRUPTIBLE);
- 	if (!dm_add_wait_queue(md, &wq, dm_get_event_nr(md))) {
- 		schedule();
- 		dm_remove_wait_queue(md, &wq);
- 	}
-  	set_current_state(TASK_RUNNING);
- 	dm_put(md);
-
-      out:
-	return results_to_user(user, param, NULL, 0);
-}
-
-/*
- * Retrieves a list of devices used by a particular dm device.
- */
-static int dep(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	int r;
-	unsigned int count;
-	struct mapped_device *md;
-	struct list_head *tmp;
-	size_t len = 0;
-	struct dm_target_deps *deps = NULL;
-	struct dm_table *table;
-
-	md = find_device(param);
-	if (!md)
-		goto out;
-	table = dm_get_table(md);
-
-	/*
-	 * Setup the basic dm_ioctl structure.
-	 */
-	__info(md, param);
-
-	/*
-	 * Count the devices.
-	 */
-	count = 0;
-	list_for_each(tmp, dm_table_get_devices(table))
-	    count++;
-
-	/*
-	 * Allocate a kernel space version of the dm_target_status
-	 * struct.
-	 */
-	if (array_too_big(sizeof(*deps), sizeof(*deps->dev), count)) {
-		dm_table_put(table);
-		dm_put(md);
-		return -ENOMEM;
-	}
-
-	len = sizeof(*deps) + (sizeof(*deps->dev) * count);
-	deps = kmalloc(len, GFP_KERNEL);
-	if (!deps) {
-		dm_table_put(table);
-		dm_put(md);
-		return -ENOMEM;
-	}
-
-	/*
-	 * Fill in the devices.
-	 */
-	deps->count = count;
-	count = 0;
-	list_for_each(tmp, dm_table_get_devices(table)) {
-		struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
-		deps->dev[count++] = dd->bdev->bd_dev;
-	}
-	dm_table_put(table);
-	dm_put(md);
-
-      out:
-	r = results_to_user(user, param, deps, len);
-
-	kfree(deps);
-	return r;
-}
-
-static int remove(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	struct hash_cell *hc;
-
-	down_write(&_hash_lock);
-	hc = *param->uuid ? __get_uuid_cell(param->uuid) :
-		__get_name_cell(param->name);
-	if (!hc) {
-		DMWARN("device doesn't appear to be in the dev hash table.");
-		up_write(&_hash_lock);
-		return -EINVAL;
-	}
-
-	/*
-	 * You may ask the interface to drop its reference to an
-	 * in use device.  This is no different to unlinking a
-	 * file that someone still has open.  The device will not
-	 * actually be destroyed until the last opener closes it.
-	 * The name and uuid of the device (both are interface
-	 * properties) will be available for reuse immediately.
-	 *
-	 * You don't want to drop a _suspended_ device from the
-	 * interface, since that will leave you with no way of
-	 * resuming it.
-	 */
-	if (dm_suspended(hc->md)) {
-		DMWARN("refusing to remove a suspended device.");
-		up_write(&_hash_lock);
-		return -EPERM;
-	}
-
-	__hash_remove(hc);
-	up_write(&_hash_lock);
-	return 0;
-}
-
-static int remove_all(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	dm_hash_remove_all();
-	return 0;
-}
-
-static int suspend(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	int r;
-	struct mapped_device *md;
-
-	md = find_device(param);
-	if (!md)
-		return -ENXIO;
-
-	if (param->flags & DM_SUSPEND_FLAG)
-		r = dm_suspend(md);
-	else
-		r = dm_resume(md);
-
-	dm_put(md);
-	return r;
-}
-
-static int reload(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	int r;
-	struct mapped_device *md;
-	struct dm_table *t;
-
-	r = dm_table_create(&t, get_mode(param));
-	if (r)
-		return r;
-
-	r = populate_table(t, param);
-	if (r) {
-		dm_table_put(t);
-		return r;
-	}
-
-	md = find_device(param);
-	if (!md) {
-		dm_table_put(t);
-		return -ENXIO;
-	}
-
-	r = dm_swap_table(md, t);
-	if (r) {
-		dm_put(md);
-		dm_table_put(t);
-		return r;
-	}
-	dm_table_put(t);	/* md will have taken its own reference */
-
-	set_disk_ro(dm_disk(md), (param->flags & DM_READONLY_FLAG) ? 1 : 0);
-	dm_put(md);
-
-	r = info(param, user);
-	return r;
-}
-
-static int rename(struct dm_ioctl *param, struct dm_ioctl *user)
-{
-	int r;
-	char *new_name = (char *) param + param->data_start;
-
-	if (valid_str(new_name, (void *) param,
-		      (void *) param + param->data_size)) {
-		DMWARN("Invalid new logical volume name supplied.");
-		return -EINVAL;
-	}
-
-	r = check_name(new_name);
-	if (r)
-		return r;
-
-	return dm_hash_rename(param->name, new_name);
-}
-
-
-/*-----------------------------------------------------------------
- * Implementation of open/close/ioctl on the special char
- * device.
- *---------------------------------------------------------------*/
-static ioctl_fn lookup_ioctl(unsigned int cmd)
-{
-	static struct {
-		int cmd;
-		ioctl_fn fn;
-	} _ioctls[] = {
-		{DM_VERSION_CMD, NULL},	/* version is dealt with elsewhere */
-		{DM_REMOVE_ALL_CMD, remove_all},
-		{DM_DEV_CREATE_CMD, create},
-		{DM_DEV_REMOVE_CMD, remove},
-		{DM_DEV_RELOAD_CMD, reload},
-		{DM_DEV_RENAME_CMD, rename},
-		{DM_DEV_SUSPEND_CMD, suspend},
-		{DM_DEV_DEPS_CMD, dep},
-		{DM_DEV_STATUS_CMD, info},
-		{DM_TARGET_STATUS_CMD, get_status},
-		{DM_TARGET_WAIT_CMD, wait_device_event},
-	};
-
-	return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
-}
-
-/*
- * As well as checking the version compatibility this always
- * copies the kernel interface version out.
- */
-static int check_version(unsigned int cmd, struct dm_ioctl *user)
-{
-	uint32_t version[3];
-	int r = 0;
-
-	if (copy_from_user(version, user->version, sizeof(version)))
-		return -EFAULT;
-
-	if ((DM_VERSION_MAJOR != version[0]) ||
-	    (DM_VERSION_MINOR < version[1])) {
-		DMWARN("ioctl interface mismatch: "
-		       "kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
-		       DM_VERSION_MAJOR, DM_VERSION_MINOR,
-		       DM_VERSION_PATCHLEVEL,
-		       version[0], version[1], version[2], cmd);
-		r = -EINVAL;
-	}
-
-	/*
-	 * Fill in the kernel version.
-	 */
-	version[0] = DM_VERSION_MAJOR;
-	version[1] = DM_VERSION_MINOR;
-	version[2] = DM_VERSION_PATCHLEVEL;
-	if (copy_to_user(user->version, version, sizeof(version)))
-		return -EFAULT;
-
-	return r;
-}
-
-static void free_params(struct dm_ioctl *param)
-{
-	vfree(param);
-}
-
-static int copy_params(struct dm_ioctl *user, struct dm_ioctl **param)
-{
-	struct dm_ioctl tmp, *dmi;
-
-	if (copy_from_user(&tmp, user, sizeof(tmp)))
-		return -EFAULT;
-
-	if (tmp.data_size < sizeof(tmp))
-		return -EINVAL;
-
-	dmi = (struct dm_ioctl *) vmalloc(tmp.data_size);
-	if (!dmi)
-		return -ENOMEM;
-
-	if (copy_from_user(dmi, user, tmp.data_size)) {
-		vfree(dmi);
-		return -EFAULT;
-	}
-
-	*param = dmi;
-	return 0;
-}
-
-static int validate_params(uint cmd, struct dm_ioctl *param)
-{
-	/* Ignores parameters */
-	if (cmd == DM_REMOVE_ALL_CMD)
-		return 0;
-
-	/* Unless creating, either name of uuid but not both */
-	if (cmd != DM_DEV_CREATE_CMD) {
-		if ((!*param->uuid && !*param->name) ||
-		    (*param->uuid && *param->name)) {
-			DMWARN("one of name or uuid must be supplied");
-			return -EINVAL;
-		}
-	}
-
-	/* Ensure strings are terminated */
-	param->name[DM_NAME_LEN - 1] = '\0';
-	param->uuid[DM_UUID_LEN - 1] = '\0';
-
-	return 0;
-}
-
-static int ctl_ioctl(struct inode *inode, struct file *file,
-		     uint command, ulong u)
-{
-	int r = 0;
-	unsigned int cmd;
-	struct dm_ioctl *param;
-	struct dm_ioctl *user = (struct dm_ioctl *) u;
-	ioctl_fn fn = NULL;
-
-	/* only root can play with this */
-	if (!capable(CAP_SYS_ADMIN))
-		return -EACCES;
-
-	if (_IOC_TYPE(command) != DM_IOCTL)
-		return -ENOTTY;
-
-	cmd = _IOC_NR(command);
-
-	/*
-	 * Check the interface version passed in.  This also
-	 * writes out the kernels interface version.
-	 */
-	r = check_version(cmd, user);
-	if (r)
-		return r;
-
-	/*
-	 * Nothing more to do for the version command.
-	 */
-	if (cmd == DM_VERSION_CMD)
-		return 0;
-
-	fn = lookup_ioctl(cmd);
-	if (!fn) {
-		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
-		return -ENOTTY;
-	}
-
-	/*
-	 * Copy the parameters into kernel space.
-	 */
-	r = copy_params(user, &param);
-	if (r)
-		return r;
-
-	r = validate_params(cmd, param);
-	if (r) {
-		free_params(param);
-		return r;
-	}
-
-	r = fn(param, user);
-	free_params(param);
-	return r;
-}
-
-static struct file_operations _ctl_fops = {
-	.ioctl	 = ctl_ioctl,
-	.owner	 = THIS_MODULE,
-};
-
-static struct miscdevice _dm_misc = {
-	.minor		= MISC_DYNAMIC_MINOR,
-	.name		= DM_NAME,
-	.devfs_name	= "mapper/control",
-	.fops		= &_ctl_fops
-};
-
-/*
- * Create misc character device and link to DM_DIR/control.
- */
-int __init dm_interface_init(void)
-{
-	int r;
-
-	r = dm_hash_init();
-	if (r)
-		return r;
-
-	r = misc_register(&_dm_misc);
-	if (r) {
-		DMERR("misc_register failed for control device");
-		dm_hash_exit();
-		return r;
-	}
-
-	DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
-	       DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
-	       DM_DRIVER_EMAIL);
-	return 0;
-
-	if (misc_deregister(&_dm_misc) < 0)
-		DMERR("misc_deregister failed for control device");
-	dm_hash_exit();
-	return r;
-}
 
-void dm_interface_exit(void)
-{
-	if (misc_deregister(&_dm_misc) < 0)
-		DMERR("misc_deregister failed for control device");
-	dm_hash_exit();
-}
+#ifdef CONFIG_DM_IOCTL_V4
+#include "dm-ioctl-v4.c"
+#else
+#include "dm-ioctl-v1.c"
+#endif

drivers/md/dm.c

@@ -515,6 +515,11 @@ static int dm_request(request_queue_t *q, struct bio *bio)
 		down_read(&md->lock);
 	}
 
+	if (!md->map) {
+		bio_io_error(bio, bio->bi_size);
+		return 0;
+	}
+
 	__split_bio(md, bio);
 	up_read(&md->lock);
 	return 0;
@@ -671,6 +676,9 @@ static int __bind(struct mapped_device *md, struct dm_table *t)
 
 static void __unbind(struct mapped_device *md)
 {
+	if (!md->map)
+		return;
+
 	dm_table_event_callback(md->map, NULL, NULL);
 	dm_table_put(md->map);
 	md->map = NULL;
@@ -681,35 +689,26 @@ static void __unbind(struct mapped_device *md)
  * Constructor for a new device.
  */
 static int create_aux(unsigned int minor, int persistent,
-		      struct dm_table *table, struct mapped_device **result)
+		      struct mapped_device **result)
 {
-	int r;
 	struct mapped_device *md;
 
 	md = alloc_dev(minor, persistent);
 	if (!md)
 		return -ENXIO;
 
-	r = __bind(md, table);
-	if (r) {
-		free_dev(md);
-		return r;
-	}
-	dm_table_resume_targets(md->map);
-
 	*result = md;
 	return 0;
 }
 
-int dm_create(struct dm_table *table, struct mapped_device **result)
+int dm_create(struct mapped_device **result)
 {
-	return create_aux(0, 0, table, result);
+	return create_aux(0, 0, result);
 }
 
-int dm_create_with_minor(unsigned int minor,
-			 struct dm_table *table, struct mapped_device **result)
+int dm_create_with_minor(unsigned int minor, struct mapped_device **result)
 {
-	return create_aux(minor, 1, table, result);
+	return create_aux(minor, 1, result);
 }
 
 void dm_get(struct mapped_device *md)
@@ -720,7 +719,7 @@ void dm_get(struct mapped_device *md)
 void dm_put(struct mapped_device *md)
 {
 	if (atomic_dec_and_test(&md->holders)) {
-		if (!test_bit(DMF_SUSPENDED, &md->flags))
+		if (!test_bit(DMF_SUSPENDED, &md->flags) && md->map)
 			dm_table_suspend_targets(md->map);
 		__unbind(md);
 		free_dev(md);
@@ -810,7 +809,8 @@ int dm_suspend(struct mapped_device *md)
 	down_write(&md->lock);
 	remove_wait_queue(&md->wait, &wait);
 	set_bit(DMF_SUSPENDED, &md->flags);
-	dm_table_suspend_targets(md->map);
+	if (md->map)
+		dm_table_suspend_targets(md->map);
 	up_write(&md->lock);
 
 	return 0;
@@ -821,7 +821,8 @@ int dm_resume(struct mapped_device *md)
 	struct deferred_io *def;
 
 	down_write(&md->lock);
-	if (!test_bit(DMF_SUSPENDED, &md->flags) ||
+	if (!md->map ||
+	    !test_bit(DMF_SUSPENDED, &md->flags) ||
 	    !dm_table_get_size(md->map)) {
 		up_write(&md->lock);
 		return -EINVAL;
@@ -891,7 +892,8 @@ struct dm_table *dm_get_table(struct mapped_device *md)
 
 	down_read(&md->lock);
 	t = md->map;
-	dm_table_get(t);
+	if (t)
+		dm_table_get(t);
 	up_read(&md->lock);
 
 	return t;

drivers/md/dm.h

@@ -51,9 +51,8 @@ struct mapped_device;
  * Functions for manipulating a struct mapped_device.
  * Drop the reference with dm_put when you finish with the object.
  *---------------------------------------------------------------*/
-int dm_create(struct dm_table *table, struct mapped_device **md);
-int dm_create_with_minor(unsigned int minor, struct dm_table *table,
-			 struct mapped_device **md);
+int dm_create(struct mapped_device **md);
+int dm_create_with_minor(unsigned int minor, struct mapped_device **md);
 
 /*
  * Reference counting for md.

include/linux/dm-ioctl-v1.h

+/*
+ * Copyright (C) 2001 Sistina Software (UK) Limited.
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef _LINUX_DM_IOCTL_V1_H
+#define _LINUX_DM_IOCTL_V1_H
+
+#include <linux/types.h>
+
+#define DM_DIR "mapper"	/* Slashes not supported */
+#define DM_MAX_TYPE_NAME 16
+#define DM_NAME_LEN 128
+#define DM_UUID_LEN 129
+
+/*
+ * Implements a traditional ioctl interface to the device mapper.
+ */
+
+/*
+ * All ioctl arguments consist of a single chunk of memory, with
+ * this structure at the start.  If a uuid is specified any
+ * lookup (eg. for a DM_INFO) will be done on that, *not* the
+ * name.
+ */
+struct dm_ioctl {
+	/*
+	 * The version number is made up of three parts:
+	 * major - no backward or forward compatibility,
+	 * minor - only backwards compatible,
+	 * patch - both backwards and forwards compatible.
+	 *
+	 * All clients of the ioctl interface should fill in the
+	 * version number of the interface that they were
+	 * compiled with.
+	 *
+	 * All recognised ioctl commands (ie. those that don't
+	 * return -ENOTTY) fill out this field, even if the
+	 * command failed.
+	 */
+	uint32_t version[3];	/* in/out */
+	uint32_t data_size;	/* total size of data passed in
+				 * including this struct */
+
+	uint32_t data_start;	/* offset to start of data
+				 * relative to start of this struct */
+
+	uint32_t target_count;	/* in/out */
+	uint32_t open_count;	/* out */
+	uint32_t flags;		/* in/out */
+
+	__kernel_dev_t dev;	/* in/out */
+
+	char name[DM_NAME_LEN];	/* device name */
+	char uuid[DM_UUID_LEN];	/* unique identifier for
+				 * the block device */
+};
+
+/*
+ * Used to specify tables.  These structures appear after the
+ * dm_ioctl.
+ */
+struct dm_target_spec {
+	int32_t status;		/* used when reading from kernel only */
+	uint64_t sector_start;
+	uint32_t length;
+
+	/*
+	 * Offset in bytes (from the start of this struct) to
+	 * next target_spec.
+	 */
+	uint32_t next;
+
+	char target_type[DM_MAX_TYPE_NAME];
+
+	/*
+	 * Parameter string starts immediately after this object.
+	 * Be careful to add padding after string to ensure correct
+	 * alignment of subsequent dm_target_spec.
+	 */
+};
+
+/*
+ * Used to retrieve the target dependencies.
+ */
+struct dm_target_deps {
+	uint32_t count;
+
+	__kernel_dev_t dev[0];	/* out */
+};
+
+/*
+ * If you change this make sure you make the corresponding change
+ * to dm-ioctl.c:lookup_ioctl()
+ */
+enum {
+	/* Top level cmds */
+	DM_VERSION_CMD = 0,
+	DM_REMOVE_ALL_CMD,
+
+	/* device level cmds */
+	DM_DEV_CREATE_CMD,
+	DM_DEV_REMOVE_CMD,
+	DM_DEV_RELOAD_CMD,
+	DM_DEV_RENAME_CMD,
+	DM_DEV_SUSPEND_CMD,
+	DM_DEV_DEPS_CMD,
+	DM_DEV_STATUS_CMD,
+
+	/* target level cmds */
+	DM_TARGET_STATUS_CMD,
+	DM_TARGET_WAIT_CMD
+};
+
+#define DM_IOCTL 0xfd
+
+#define DM_VERSION       _IOWR(DM_IOCTL, DM_VERSION_CMD, struct dm_ioctl)
+#define DM_REMOVE_ALL    _IOWR(DM_IOCTL, DM_REMOVE_ALL_CMD, struct dm_ioctl)
+
+#define DM_DEV_CREATE    _IOWR(DM_IOCTL, DM_DEV_CREATE_CMD, struct dm_ioctl)
+#define DM_DEV_REMOVE    _IOWR(DM_IOCTL, DM_DEV_REMOVE_CMD, struct dm_ioctl)
+#define DM_DEV_RELOAD    _IOWR(DM_IOCTL, DM_DEV_RELOAD_CMD, struct dm_ioctl)
+#define DM_DEV_SUSPEND   _IOWR(DM_IOCTL, DM_DEV_SUSPEND_CMD, struct dm_ioctl)
+#define DM_DEV_RENAME    _IOWR(DM_IOCTL, DM_DEV_RENAME_CMD, struct dm_ioctl)
+#define DM_DEV_DEPS      _IOWR(DM_IOCTL, DM_DEV_DEPS_CMD, struct dm_ioctl)
+#define DM_DEV_STATUS    _IOWR(DM_IOCTL, DM_DEV_STATUS_CMD, struct dm_ioctl)
+
+#define DM_TARGET_STATUS _IOWR(DM_IOCTL, DM_TARGET_STATUS_CMD, struct dm_ioctl)
+#define DM_TARGET_WAIT   _IOWR(DM_IOCTL, DM_TARGET_WAIT_CMD, struct dm_ioctl)
+
+#define DM_VERSION_MAJOR	1
+#define DM_VERSION_MINOR	0
+#define DM_VERSION_PATCHLEVEL	6
+#define DM_VERSION_EXTRA	"-ioctl (2002-10-15)"
+
+/* Status bits */
+#define DM_READONLY_FLAG	0x00000001
+#define DM_SUSPEND_FLAG		0x00000002
+#define DM_EXISTS_FLAG		0x00000004
+#define DM_PERSISTENT_DEV_FLAG	0x00000008
+
+/*
+ * Flag passed into ioctl STATUS command to get table information
+ * rather than current status.
+ */
+#define DM_STATUS_TABLE_FLAG	0x00000010
+
+#endif				/* _LINUX_DM_IOCTL_H */

include/linux/dm-ioctl-v4.h

+/*
+ * Copyright (C) 2001 - 2003 Sistina Software (UK) Limited.
+ *
+ * This file is released under the LGPL.
+ */
+
+#ifndef _LINUX_DM_IOCTL_V4_H
+#define _LINUX_DM_IOCTL_V4_H
+
+#include <linux/types.h>
+
+#define DM_DIR "mapper"		/* Slashes not supported */
+#define DM_MAX_TYPE_NAME 16
+#define DM_NAME_LEN 128
+#define DM_UUID_LEN 129
+
+/*
+ * A traditional ioctl interface for the device mapper.
+ *
+ * Each device can have two tables associated with it, an
+ * 'active' table which is the one currently used by io passing
+ * through the device, and an 'inactive' one which is a table
+ * that is being prepared as a replacement for the 'active' one.
+ *
+ * DM_VERSION:
+ * Just get the version information for the ioctl interface.
+ *
+ * DM_REMOVE_ALL:
+ * Remove all dm devices, destroy all tables.  Only really used
+ * for debug.
+ *
+ * DM_LIST_DEVICES:
+ * Get a list of all the dm device names.
+ *
+ * DM_DEV_CREATE:
+ * Create a new device, neither the 'active' or 'inactive' table
+ * slots will be filled.  The device will be in suspended state
+ * after creation, however any io to the device will get errored
+ * since it will be out-of-bounds.
+ *
+ * DM_DEV_REMOVE:
+ * Remove a device, destroy any tables.
+ *
+ * DM_DEV_RENAME:
+ * Rename a device.
+ *
+ * DM_SUSPEND:
+ * This performs both suspend and resume, depending which flag is
+ * passed in.
+ * Suspend: This command will not return until all pending io to
+ * the device has completed.  Further io will be deferred until
+ * the device is resumed.
+ * Resume: It is no longer an error to issue this command on an
+ * unsuspended device.  If a table is present in the 'inactive'
+ * slot, it will be moved to the active slot, then the old table
+ * from the active slot will be _destroyed_.  Finally the device
+ * is resumed.
+ *
+ * DM_DEV_STATUS:
+ * Retrieves the status for the table in the 'active' slot.
+ *
+ * DM_DEV_WAIT:
+ * Wait for a significant event to occur to the device.  This
+ * could either be caused by an event triggered by one of the
+ * targets of the table in the 'active' slot, or a table change.
+ *
+ * DM_TABLE_LOAD:
+ * Load a table into the 'inactive' slot for the device.  The
+ * device does _not_ need to be suspended prior to this command.
+ *
+ * DM_TABLE_CLEAR:
+ * Destroy any table in the 'inactive' slot (ie. abort).
+ *
+ * DM_TABLE_DEPS:
+ * Return a set of device dependencies for the 'active' table.
+ *
+ * DM_TABLE_STATUS:
+ * Return the targets status for the 'active' table.
+ */
+
+/*
+ * All ioctl arguments consist of a single chunk of memory, with
+ * this structure at the start.  If a uuid is specified any
+ * lookup (eg. for a DM_INFO) will be done on that, *not* the
+ * name.
+ */
+struct dm_ioctl {
+	/*
+	 * The version number is made up of three parts:
+	 * major - no backward or forward compatibility,
+	 * minor - only backwards compatible,
+	 * patch - both backwards and forwards compatible.
+	 *
+	 * All clients of the ioctl interface should fill in the
+	 * version number of the interface that they were
+	 * compiled with.
+	 *
+	 * All recognised ioctl commands (ie. those that don't
+	 * return -ENOTTY) fill out this field, even if the
+	 * command failed.
+	 */
+	uint32_t version[3];	/* in/out */
+	uint32_t data_size;	/* total size of data passed in
+				 * including this struct */
+
+	uint32_t data_start;	/* offset to start of data
+				 * relative to start of this struct */
+
+	uint32_t target_count;	/* in/out */
+	int32_t open_count;	/* out */
+	uint32_t flags;		/* in/out */
+	uint32_t event_nr;      	/* in/out */
+	uint32_t padding;
+
+	uint64_t dev;		/* in/out */
+
+	char name[DM_NAME_LEN];	/* device name */
+	char uuid[DM_UUID_LEN];	/* unique identifier for
+				 * the block device */
+};
+
+/*
+ * Used to specify tables.  These structures appear after the
+ * dm_ioctl.
+ */
+struct dm_target_spec {
+	uint64_t sector_start;
+	uint64_t length;
+	int32_t status;		/* used when reading from kernel only */
+
+	/*
+	 * Offset in bytes (from the start of this struct) to
+	 * next target_spec.
+	 */
+	uint32_t next;
+
+	char target_type[DM_MAX_TYPE_NAME];
+
+	/*
+	 * Parameter string starts immediately after this object.
+	 * Be careful to add padding after string to ensure correct
+	 * alignment of subsequent dm_target_spec.
+	 */
+};
+
+/*
+ * Used to retrieve the target dependencies.
+ */
+struct dm_target_deps {
+	uint32_t count;	/* Array size */
+	uint32_t padding;	/* unused */
+	uint64_t dev[0];	/* out */
+};
+
+/*
+ * Used to get a list of all dm devices.
+ */
+struct dm_name_list {
+	uint64_t dev;
+	uint32_t next;		/* offset to the next record from
+				   the _start_ of this */
+	char name[0];
+};
+
+/*
+ * If you change this make sure you make the corresponding change
+ * to dm-ioctl.c:lookup_ioctl()
+ */
+enum {
+	/* Top level cmds */
+	DM_VERSION_CMD = 0,
+	DM_REMOVE_ALL_CMD,
+	DM_LIST_DEVICES_CMD,
+
+	/* device level cmds */
+	DM_DEV_CREATE_CMD,
+	DM_DEV_REMOVE_CMD,
+	DM_DEV_RENAME_CMD,
+	DM_DEV_SUSPEND_CMD,
+	DM_DEV_STATUS_CMD,
+	DM_DEV_WAIT_CMD,
+
+	/* Table level cmds */
+	DM_TABLE_LOAD_CMD,
+	DM_TABLE_CLEAR_CMD,
+	DM_TABLE_DEPS_CMD,
+	DM_TABLE_STATUS_CMD,
+};
+
+#define DM_IOCTL 0xfd
+
+#define DM_VERSION       _IOWR(DM_IOCTL, DM_VERSION_CMD, struct dm_ioctl)
+#define DM_REMOVE_ALL    _IOWR(DM_IOCTL, DM_REMOVE_ALL_CMD, struct dm_ioctl)
+#define DM_LIST_DEVICES  _IOWR(DM_IOCTL, DM_LIST_DEVICES_CMD, struct dm_ioctl)
+
+#define DM_DEV_CREATE    _IOWR(DM_IOCTL, DM_DEV_CREATE_CMD, struct dm_ioctl)
+#define DM_DEV_REMOVE    _IOWR(DM_IOCTL, DM_DEV_REMOVE_CMD, struct dm_ioctl)
+#define DM_DEV_RENAME    _IOWR(DM_IOCTL, DM_DEV_RENAME_CMD, struct dm_ioctl)
+#define DM_DEV_SUSPEND   _IOWR(DM_IOCTL, DM_DEV_SUSPEND_CMD, struct dm_ioctl)
+#define DM_DEV_STATUS    _IOWR(DM_IOCTL, DM_DEV_STATUS_CMD, struct dm_ioctl)
+#define DM_DEV_WAIT      _IOWR(DM_IOCTL, DM_DEV_WAIT_CMD, struct dm_ioctl)
+
+#define DM_TABLE_LOAD    _IOWR(DM_IOCTL, DM_TABLE_LOAD_CMD, struct dm_ioctl)
+#define DM_TABLE_CLEAR   _IOWR(DM_IOCTL, DM_TABLE_CLEAR_CMD, struct dm_ioctl)
+#define DM_TABLE_DEPS    _IOWR(DM_IOCTL, DM_TABLE_DEPS_CMD, struct dm_ioctl)
+#define DM_TABLE_STATUS  _IOWR(DM_IOCTL, DM_TABLE_STATUS_CMD, struct dm_ioctl)
+
+#define DM_VERSION_MAJOR	4
+#define DM_VERSION_MINOR	0
+#define DM_VERSION_PATCHLEVEL	0
+#define DM_VERSION_EXTRA	"-ioctl (2003-06-04)"
+
+/* Status bits */
+#define DM_READONLY_FLAG	(1 << 0) /* In/Out */
+#define DM_SUSPEND_FLAG		(1 << 1) /* In/Out */
+#define DM_PERSISTENT_DEV_FLAG	(1 << 3) /* In */
+
+/*
+ * Flag passed into ioctl STATUS command to get table information
+ * rather than current status.
+ */
+#define DM_STATUS_TABLE_FLAG	(1 << 4) /* In */
+
+/*
+ * Flags that indicate whether a table is present in either of
+ * the two table slots that a device has.
+ */
+#define DM_ACTIVE_PRESENT_FLAG   (1 << 5) /* Out */
+#define DM_INACTIVE_PRESENT_FLAG (1 << 6) /* Out */
+
+/*
+ * Indicates that the buffer passed in wasn't big enough for the
+ * results.
+ */
+#define DM_BUFFER_FULL_FLAG	(1 << 8) /* Out */
+
+#endif				/* _LINUX_DM_IOCTL_H */

include/linux/dm-ioctl.h

 /*
- * Copyright (C) 2001 Sistina Software (UK) Limited.
+ * Copyright (C) 2003 Sistina Software (UK) Limited.
  *
  * This file is released under the LGPL.
  */
@@ -7,143 +7,12 @@
 #ifndef _LINUX_DM_IOCTL_H
 #define _LINUX_DM_IOCTL_H
 
-#include <linux/types.h>
+#include <linux/config.h>
 
-#define DM_DIR "mapper"	/* Slashes not supported */
-#define DM_MAX_TYPE_NAME 16
-#define DM_NAME_LEN 128
-#define DM_UUID_LEN 129
+#ifdef CONFIG_DM_IOCTL_V4
+#include "dm-ioctl-v4.h"
+#else
+#include "dm-ioctl-v1.h"
+#endif
 
-/*
- * Implements a traditional ioctl interface to the device mapper.
- */
-
-/*
- * All ioctl arguments consist of a single chunk of memory, with
- * this structure at the start.  If a uuid is specified any
- * lookup (eg. for a DM_INFO) will be done on that, *not* the
- * name.
- */
-struct dm_ioctl {
-	/*
-	 * The version number is made up of three parts:
-	 * major - no backward or forward compatibility,
-	 * minor - only backwards compatible,
-	 * patch - both backwards and forwards compatible.
-	 *
-	 * All clients of the ioctl interface should fill in the
-	 * version number of the interface that they were
-	 * compiled with.
-	 *
-	 * All recognised ioctl commands (ie. those that don't
-	 * return -ENOTTY) fill out this field, even if the
-	 * command failed.
-	 */
-	uint32_t version[3];	/* in/out */
-	uint32_t data_size;	/* total size of data passed in
-				 * including this struct */
-
-	uint32_t data_start;	/* offset to start of data
-				 * relative to start of this struct */
-
-	uint32_t target_count;	/* in/out */
-	uint32_t open_count;	/* out */
-	uint32_t flags;		/* in/out */
-
-	__kernel_dev_t dev;	/* in/out */
-
-	char name[DM_NAME_LEN];	/* device name */
-	char uuid[DM_UUID_LEN];	/* unique identifier for
-				 * the block device */
-};
-
-/*
- * Used to specify tables.  These structures appear after the
- * dm_ioctl.
- */
-struct dm_target_spec {
-	int32_t status;		/* used when reading from kernel only */
-	uint64_t sector_start;
-	uint32_t length;
-
-	/*
-	 * Offset in bytes (from the start of this struct) to
-	 * next target_spec.
-	 */
-	uint32_t next;
-
-	char target_type[DM_MAX_TYPE_NAME];
-
-	/*
-	 * Parameter string starts immediately after this object.
-	 * Be careful to add padding after string to ensure correct
-	 * alignment of subsequent dm_target_spec.
-	 */
-};
-
-/*
- * Used to retrieve the target dependencies.
- */
-struct dm_target_deps {
-	uint32_t count;
-
-	__kernel_dev_t dev[0];	/* out */
-};
-
-/*
- * If you change this make sure you make the corresponding change
- * to dm-ioctl.c:lookup_ioctl()
- */
-enum {
-	/* Top level cmds */
-	DM_VERSION_CMD = 0,
-	DM_REMOVE_ALL_CMD,
-
-	/* device level cmds */
-	DM_DEV_CREATE_CMD,
-	DM_DEV_REMOVE_CMD,
-	DM_DEV_RELOAD_CMD,
-	DM_DEV_RENAME_CMD,
-	DM_DEV_SUSPEND_CMD,
-	DM_DEV_DEPS_CMD,
-	DM_DEV_STATUS_CMD,
-
-	/* target level cmds */
-	DM_TARGET_STATUS_CMD,
-	DM_TARGET_WAIT_CMD
-};
-
-#define DM_IOCTL 0xfd
-
-#define DM_VERSION       _IOWR(DM_IOCTL, DM_VERSION_CMD, struct dm_ioctl)
-#define DM_REMOVE_ALL    _IOWR(DM_IOCTL, DM_REMOVE_ALL_CMD, struct dm_ioctl)
-
-#define DM_DEV_CREATE    _IOWR(DM_IOCTL, DM_DEV_CREATE_CMD, struct dm_ioctl)
-#define DM_DEV_REMOVE    _IOWR(DM_IOCTL, DM_DEV_REMOVE_CMD, struct dm_ioctl)
-#define DM_DEV_RELOAD    _IOWR(DM_IOCTL, DM_DEV_RELOAD_CMD, struct dm_ioctl)
-#define DM_DEV_SUSPEND   _IOWR(DM_IOCTL, DM_DEV_SUSPEND_CMD, struct dm_ioctl)
-#define DM_DEV_RENAME    _IOWR(DM_IOCTL, DM_DEV_RENAME_CMD, struct dm_ioctl)
-#define DM_DEV_DEPS      _IOWR(DM_IOCTL, DM_DEV_DEPS_CMD, struct dm_ioctl)
-#define DM_DEV_STATUS    _IOWR(DM_IOCTL, DM_DEV_STATUS_CMD, struct dm_ioctl)
-
-#define DM_TARGET_STATUS _IOWR(DM_IOCTL, DM_TARGET_STATUS_CMD, struct dm_ioctl)
-#define DM_TARGET_WAIT   _IOWR(DM_IOCTL, DM_TARGET_WAIT_CMD, struct dm_ioctl)
-
-#define DM_VERSION_MAJOR	1
-#define DM_VERSION_MINOR	0
-#define DM_VERSION_PATCHLEVEL	6
-#define DM_VERSION_EXTRA	"-ioctl (2002-10-15)"
-
-/* Status bits */
-#define DM_READONLY_FLAG	0x00000001
-#define DM_SUSPEND_FLAG		0x00000002
-#define DM_EXISTS_FLAG		0x00000004
-#define DM_PERSISTENT_DEV_FLAG	0x00000008
-
-/*
- * Flag passed into ioctl STATUS command to get table information
- * rather than current status.
- */
-#define DM_STATUS_TABLE_FLAG	0x00000010
-
-#endif				/* _LINUX_DM_IOCTL_H */
+#endif