Initial import

1 files changed, 1958 insertions, 0 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
new file mode 100644
index 000000000..720ceeb7f
--- /dev/null
+++ b/drivers/md/dm-ioctl.c
@@ -0,0 +1,1958 @@
+/*
+ * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ * Copyright (C) 2004 - 2006 Red Hat, Inc. All rights reserved.
+ *
+ * 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/slab.h>
+#include <linux/dm-ioctl.h>
+#include <linux/hdreg.h>
+#include <linux/compat.h>
+
+#include <asm/uaccess.h>
+
+#define DM_MSG_PREFIX "ioctl"
+#define DM_DRIVER_EMAIL "dm-devel@redhat.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;
+};
+
+/*
+ * A dummy definition to make RCU happy.
+ * struct dm_table should never be dereferenced in this file.
+ */
+struct dm_table {
+	int undefined__;
+};
+
+struct vers_iter {
+    size_t param_size;
+    struct dm_target_versions *vers, *old_vers;
+    char *end;
+    uint32_t flags;
+};
+
+
+#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];
+
+static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
+
+/*
+ * Guards access to both hash tables.
+ */
+static DECLARE_RWSEM(_hash_lock);
+
+/*
+ * Protects use of mdptr to obtain hash cell name and uuid from mapped device.
+ */
+static DEFINE_MUTEX(dm_hash_cells_mutex);
+
+static void init_buckets(struct list_head *buckets)
+{
+	unsigned int i;
+
+	for (i = 0; i < NUM_BUCKETS; i++)
+		INIT_LIST_HEAD(buckets + i);
+}
+
+static int dm_hash_init(void)
+{
+	init_buckets(_name_buckets);
+	init_buckets(_uuid_buckets);
+	return 0;
+}
+
+static void dm_hash_exit(void)
+{
+	dm_hash_remove_all(false, false, false);
+}
+
+/*-----------------------------------------------------------------
+ * 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 hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each_entry (hc, _name_buckets + h, name_list)
+		if (!strcmp(hc->name, str)) {
+			dm_get(hc->md);
+			return hc;
+		}
+
+	return NULL;
+}
+
+static struct hash_cell *__get_uuid_cell(const char *str)
+{
+	struct hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each_entry (hc, _uuid_buckets + h, uuid_list)
+		if (!strcmp(hc->uuid, str)) {
+			dm_get(hc->md);
+			return hc;
+		}
+
+	return NULL;
+}
+
+static struct hash_cell *__get_dev_cell(uint64_t dev)
+{
+	struct mapped_device *md;
+	struct hash_cell *hc;
+
+	md = dm_get_md(huge_decode_dev(dev));
+	if (!md)
+		return NULL;
+
+	hc = dm_get_mdptr(md);
+	if (!hc) {
+		dm_put(md);
+		return NULL;
+	}
+
+	return hc;
+}
+
+/*-----------------------------------------------------------------
+ * Inserting, removing and renaming a device.
+ *---------------------------------------------------------------*/
+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, GFP_KERNEL);
+	if (!hc->name) {
+		kfree(hc);
+		return NULL;
+	}
+
+	if (!uuid)
+		hc->uuid = NULL;
+
+	else {
+		hc->uuid = kstrdup(uuid, GFP_KERNEL);
+		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);
+	}
+}
+
+/*
+ * The kdev_t and uuid of a device can never change once it is
+ * initially inserted.
+ */
+static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
+{
+	struct hash_cell *cell, *hc;
+
+	/*
+	 * 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);
+	hc = __get_name_cell(name);
+	if (hc) {
+		dm_put(hc->md);
+		goto bad;
+	}
+
+	list_add(&cell->name_list, _name_buckets + hash_str(name));
+
+	if (uuid) {
+		hc = __get_uuid_cell(uuid);
+		if (hc) {
+			list_del(&cell->name_list);
+			dm_put(hc->md);
+			goto bad;
+		}
+		list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
+	}
+	dm_get(md);
+	mutex_lock(&dm_hash_cells_mutex);
+	dm_set_mdptr(md, cell);
+	mutex_unlock(&dm_hash_cells_mutex);
+	up_write(&_hash_lock);
+
+	return 0;
+
+ bad:
+	up_write(&_hash_lock);
+	free_cell(cell);
+	return -EBUSY;
+}
+
+static struct dm_table *__hash_remove(struct hash_cell *hc)
+{
+	struct dm_table *table;
+	int srcu_idx;
+
+	/* remove from the dev hash */
+	list_del(&hc->uuid_list);
+	list_del(&hc->name_list);
+	mutex_lock(&dm_hash_cells_mutex);
+	dm_set_mdptr(hc->md, NULL);
+	mutex_unlock(&dm_hash_cells_mutex);
+
+	table = dm_get_live_table(hc->md, &srcu_idx);
+	if (table)
+		dm_table_event(table);
+	dm_put_live_table(hc->md, srcu_idx);
+
+	table = NULL;
+	if (hc->new_map)
+		table = hc->new_map;
+	dm_put(hc->md);
+	free_cell(hc);
+
+	return table;
+}
+
+static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
+{
+	int i, dev_skipped;
+	struct hash_cell *hc;
+	struct mapped_device *md;
+	struct dm_table *t;
+
+retry:
+	dev_skipped = 0;
+
+	down_write(&_hash_lock);
+
+	for (i = 0; i < NUM_BUCKETS; i++) {
+		list_for_each_entry(hc, _name_buckets + i, name_list) {
+			md = hc->md;
+			dm_get(md);
+
+			if (keep_open_devices &&
+			    dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
+				dm_put(md);
+				dev_skipped++;
+				continue;
+			}
+
+			t = __hash_remove(hc);
+
+			up_write(&_hash_lock);
+
+			if (t) {
+				dm_sync_table(md);
+				dm_table_destroy(t);
+			}
+			dm_put(md);
+			if (likely(keep_open_devices))
+				dm_destroy(md);
+			else
+				dm_destroy_immediate(md);
+
+			/*
+			 * Some mapped devices may be using other mapped
+			 * devices, so repeat until we make no further
+			 * progress.  If a new mapped device is created
+			 * here it will also get removed.
+			 */
+			goto retry;
+		}
+	}
+
+	up_write(&_hash_lock);
+
+	if (dev_skipped)
+		DMWARN("remove_all left %d open device(s)", dev_skipped);
+}
+
+/*
+ * Set the uuid of a hash_cell that isn't already set.
+ */
+static void __set_cell_uuid(struct hash_cell *hc, char *new_uuid)
+{
+	mutex_lock(&dm_hash_cells_mutex);
+	hc->uuid = new_uuid;
+	mutex_unlock(&dm_hash_cells_mutex);
+
+	list_add(&hc->uuid_list, _uuid_buckets + hash_str(new_uuid));
+}
+
+/*
+ * Changes the name of a hash_cell and returns the old name for
+ * the caller to free.
+ */
+static char *__change_cell_name(struct hash_cell *hc, char *new_name)
+{
+	char *old_name;
+
+	/*
+	 * Rename and move the name cell.
+	 */
+	list_del(&hc->name_list);
+	old_name = hc->name;
+
+	mutex_lock(&dm_hash_cells_mutex);
+	hc->name = new_name;
+	mutex_unlock(&dm_hash_cells_mutex);
+
+	list_add(&hc->name_list, _name_buckets + hash_str(new_name));
+
+	return old_name;
+}
+
+static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
+					    const char *new)
+{
+	char *new_data, *old_name = NULL;
+	struct hash_cell *hc;
+	struct dm_table *table;
+	struct mapped_device *md;
+	unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
+	int srcu_idx;
+
+	/*
+	 * duplicate new.
+	 */
+	new_data = kstrdup(new, GFP_KERNEL);
+	if (!new_data)
+		return ERR_PTR(-ENOMEM);
+
+	down_write(&_hash_lock);
+
+	/*
+	 * Is new free ?
+	 */
+	if (change_uuid)
+		hc = __get_uuid_cell(new);
+	else
+		hc = __get_name_cell(new);
+
+	if (hc) {
+		DMWARN("Unable to change %s on mapped device %s to one that "
+		       "already exists: %s",
+		       change_uuid ? "uuid" : "name",
+		       param->name, new);
+		dm_put(hc->md);
+		up_write(&_hash_lock);
+		kfree(new_data);
+		return ERR_PTR(-EBUSY);
+	}
+
+	/*
+	 * Is there such a device as 'old' ?
+	 */
+	hc = __get_name_cell(param->name);
+	if (!hc) {
+		DMWARN("Unable to rename non-existent device, %s to %s%s",
+		       param->name, change_uuid ? "uuid " : "", new);
+		up_write(&_hash_lock);
+		kfree(new_data);
+		return ERR_PTR(-ENXIO);
+	}
+
+	/*
+	 * Does this device already have a uuid?
+	 */
+	if (change_uuid && hc->uuid) {
+		DMWARN("Unable to change uuid of mapped device %s to %s "
+		       "because uuid is already set to %s",
+		       param->name, new, hc->uuid);
+		dm_put(hc->md);
+		up_write(&_hash_lock);
+		kfree(new_data);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (change_uuid)
+		__set_cell_uuid(hc, new_data);
+	else
+		old_name = __change_cell_name(hc, new_data);
+
+	/*
+	 * Wake up any dm event waiters.
+	 */
+	table = dm_get_live_table(hc->md, &srcu_idx);
+	if (table)
+		dm_table_event(table);
+	dm_put_live_table(hc->md, srcu_idx);
+
+	if (!dm_kobject_uevent(hc->md, KOBJ_CHANGE, param->event_nr))
+		param->flags |= DM_UEVENT_GENERATED_FLAG;
+
+	md = hc->md;
+	up_write(&_hash_lock);
+	kfree(old_name);
+
+	return md;
+}
+
+void dm_deferred_remove(void)
+{
+	dm_hash_remove_all(true, false, true);
+}
+
+/*-----------------------------------------------------------------
+ * 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(true, !!(param->flags & DM_DEFERRED_REMOVE), false);
+	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) + 1;
+			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 = huge_encode_dev(disk_devt(disk));
+			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 void list_version_get_needed(struct target_type *tt, void *needed_param)
+{
+    size_t *needed = needed_param;
+
+    *needed += sizeof(struct dm_target_versions);
+    *needed += strlen(tt->name);
+    *needed += ALIGN_MASK;
+}
+
+static void list_version_get_info(struct target_type *tt, void *param)
+{
+    struct vers_iter *info = param;
+
+    /* Check space - it might have changed since the first iteration */
+    if ((char *)info->vers + sizeof(tt->version) + strlen(tt->name) + 1 >
+	info->end) {
+
+	info->flags = DM_BUFFER_FULL_FLAG;
+	return;
+    }
+
+    if (info->old_vers)
+	info->old_vers->next = (uint32_t) ((void *)info->vers -
+					   (void *)info->old_vers);
+    info->vers->version[0] = tt->version[0];
+    info->vers->version[1] = tt->version[1];
+    info->vers->version[2] = tt->version[2];
+    info->vers->next = 0;
+    strcpy(info->vers->name, tt->name);
+
+    info->old_vers = info->vers;
+    info->vers = align_ptr(((void *) ++info->vers) + strlen(tt->name) + 1);
+}
+
+static int list_versions(struct dm_ioctl *param, size_t param_size)
+{
+	size_t len, needed = 0;
+	struct dm_target_versions *vers;
+	struct vers_iter iter_info;
+
+	/*
+	 * Loop through all the devices working out how much
+	 * space we need.
+	 */
+	dm_target_iterate(list_version_get_needed, &needed);
+
+	/*
+	 * Grab our output buffer.
+	 */
+	vers = 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;
+
+	iter_info.param_size = param_size;
+	iter_info.old_vers = NULL;
+	iter_info.vers = vers;
+	iter_info.flags = 0;
+	iter_info.end = (char *)vers+len;
+
+	/*
+	 * Now loop through filling out the names & versions.
+	 */
+	dm_target_iterate(list_version_get_info, &iter_info);
+	param->flags |= iter_info.flags;
+
+ out:
+	return 0;
+}
+
+static int check_name(const char *name)
+{
+	if (strchr(name, '/')) {
+		DMWARN("invalid device name");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * On successful return, the caller must not attempt to acquire
+ * _hash_lock without first calling dm_put_live_table, because dm_table_destroy
+ * waits for this dm_put_live_table and could be called under this lock.
+ */
+static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *srcu_idx)
+{
+	struct hash_cell *hc;
+	struct dm_table *table = NULL;
+
+	/* increment rcu count, we don't care about the table pointer */
+	dm_get_live_table(md, srcu_idx);
+
+	down_read(&_hash_lock);
+	hc = dm_get_mdptr(md);
+	if (!hc || hc->md != md) {
+		DMWARN("device has been removed from the dev hash table.");
+		goto out;
+	}
+
+	table = hc->new_map;
+
+out:
+	up_read(&_hash_lock);
+
+	return table;
+}
+
+static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md,
+						      struct dm_ioctl *param,
+						      int *srcu_idx)
+{
+	return (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) ?
+		dm_get_inactive_table(md, srcu_idx) : dm_get_live_table(md, srcu_idx);
+}
+
+/*
+ * Fills in a dm_ioctl structure, ready for sending back to
+ * userland.
+ */
+static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
+{
+	struct gendisk *disk = dm_disk(md);
+	struct dm_table *table;
+	int srcu_idx;
+
+	param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
+			  DM_ACTIVE_PRESENT_FLAG | DM_INTERNAL_SUSPEND_FLAG);
+
+	if (dm_suspended_md(md))
+		param->flags |= DM_SUSPEND_FLAG;
+
+	if (dm_suspended_internally_md(md))
+		param->flags |= DM_INTERNAL_SUSPEND_FLAG;
+
+	if (dm_test_deferred_remove_flag(md))
+		param->flags |= DM_DEFERRED_REMOVE;
+
+	param->dev = huge_encode_dev(disk_devt(disk));
+
+	/*
+	 * Yes, this will be out of date by the time it gets back
+	 * to userland, but it is still very useful for
+	 * debugging.
+	 */
+	param->open_count = dm_open_count(md);
+
+	param->event_nr = dm_get_event_nr(md);
+	param->target_count = 0;
+
+	table = dm_get_live_table(md, &srcu_idx);
+	if (table) {
+		if (!(param->flags & DM_QUERY_INACTIVE_TABLE_FLAG)) {
+			if (get_disk_ro(disk))
+				param->flags |= DM_READONLY_FLAG;
+			param->target_count = dm_table_get_num_targets(table);
+		}
+
+		param->flags |= DM_ACTIVE_PRESENT_FLAG;
+	}
+	dm_put_live_table(md, srcu_idx);
+
+	if (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) {
+		int srcu_idx;
+		table = dm_get_inactive_table(md, &srcu_idx);
+		if (table) {
+			if (!(dm_table_get_mode(table) & FMODE_WRITE))
+				param->flags |= DM_READONLY_FLAG;
+			param->target_count = dm_table_get_num_targets(table);
+		}
+		dm_put_live_table(md, srcu_idx);
+	}
+}
+
+static int dev_create(struct dm_ioctl *param, size_t param_size)
+{
+	int r, m = DM_ANY_MINOR;
+	struct mapped_device *md;
+
+	r = check_name(param->name);
+	if (r)
+		return r;
+
+	if (param->flags & DM_PERSISTENT_DEV_FLAG)
+		m = MINOR(huge_decode_dev(param->dev));
+
+	r = dm_create(m, &md);
+	if (r)
+		return r;
+
+	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
+	if (r) {
+		dm_put(md);
+		dm_destroy(md);
+		return r;
+	}
+
+	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+	__dev_status(md, param);
+
+	dm_put(md);
+
+	return 0;
+}
+
+/*
+ * Always use UUID for lookups if it's present, otherwise use name or dev.
+ */
+static struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
+{
+	struct hash_cell *hc = NULL;
+
+	if (*param->uuid) {
+		if (*param->name || param->dev)
+			return NULL;
+
+		hc = __get_uuid_cell(param->uuid);
+		if (!hc)
+			return NULL;
+	} else if (*param->name) {
+		if (param->dev)
+			return NULL;
+
+		hc = __get_name_cell(param->name);
+		if (!hc)
+			return NULL;
+	} else if (param->dev) {
+		hc = __get_dev_cell(param->dev);
+		if (!hc)
+			return NULL;
+	} else
+		return NULL;
+
+	/*
+	 * 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';
+
+	if (hc->new_map)
+		param->flags |= DM_INACTIVE_PRESENT_FLAG;
+	else
+		param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+	return hc;
+}
+
+static 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;
+	up_read(&_hash_lock);
+
+	return md;
+}
+
+static int dev_remove(struct dm_ioctl *param, size_t param_size)
+{
+	struct hash_cell *hc;
+	struct mapped_device *md;
+	int r;
+	struct dm_table *t;
+
+	down_write(&_hash_lock);
+	hc = __find_device_hash_cell(param);
+
+	if (!hc) {
+		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	md = hc->md;
+
+	/*
+	 * Ensure the device is not open and nothing further can open it.
+	 */
+	r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE), false);
+	if (r) {
+		if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
+			up_write(&_hash_lock);
+			dm_put(md);
+			return 0;
+		}
+		DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
+		up_write(&_hash_lock);
+		dm_put(md);
+		return r;
+	}
+
+	t = __hash_remove(hc);
+	up_write(&_hash_lock);
+
+	if (t) {
+		dm_sync_table(md);
+		dm_table_destroy(t);
+	}
+
+	param->flags &= ~DM_DEFERRED_REMOVE;
+
+	if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr))
+		param->flags |= DM_UEVENT_GENERATED_FLAG;
+
+	dm_put(md);
+	dm_destroy(md);
+	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_data = (char *) param + param->data_start;
+	struct mapped_device *md;
+	unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
+
+	if (new_data < param->data ||
+	    invalid_str(new_data, (void *) param + param_size) || !*new_data ||
+	    strlen(new_data) > (change_uuid ? DM_UUID_LEN - 1 : DM_NAME_LEN - 1)) {
+		DMWARN("Invalid new mapped device name or uuid string supplied.");
+		return -EINVAL;
+	}
+
+	if (!change_uuid) {
+		r = check_name(new_data);
+		if (r)
+			return r;
+	}
+
+	md = dm_hash_rename(param, new_data);
+	if (IS_ERR(md))
+		return PTR_ERR(md);
+
+	__dev_status(md, param);
+	dm_put(md);
+
+	return 0;
+}
+
+static int dev_set_geometry(struct dm_ioctl *param, size_t param_size)
+{
+	int r = -EINVAL, x;
+	struct mapped_device *md;
+	struct hd_geometry geometry;
+	unsigned long indata[4];
+	char *geostr = (char *) param + param->data_start;
+	char dummy;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	if (geostr < param->data ||
+	    invalid_str(geostr, (void *) param + param_size)) {
+		DMWARN("Invalid geometry supplied.");
+		goto out;
+	}
+
+	x = sscanf(geostr, "%lu %lu %lu %lu%c", indata,
+		   indata + 1, indata + 2, indata + 3, &dummy);
+
+	if (x != 4) {
+		DMWARN("Unable to interpret geometry settings.");
+		goto out;
+	}
+
+	if (indata[0] > 65535 || indata[1] > 255 ||
+	    indata[2] > 255 || indata[3] > ULONG_MAX) {
+		DMWARN("Geometry exceeds range limits.");
+		goto out;
+	}
+
+	geometry.cylinders = indata[0];
+	geometry.heads = indata[1];
+	geometry.sectors = indata[2];
+	geometry.start = indata[3];
+
+	r = dm_set_geometry(md, &geometry);
+
+	param->data_size = 0;
+
+out:
+	dm_put(md);
+	return r;
+}
+
+static int do_suspend(struct dm_ioctl *param)
+{
+	int r = 0;
+	unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
+	struct mapped_device *md;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	if (param->flags & DM_SKIP_LOCKFS_FLAG)
+		suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
+	if (param->flags & DM_NOFLUSH_FLAG)
+		suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
+
+	if (!dm_suspended_md(md)) {
+		r = dm_suspend(md, suspend_flags);
+		if (r)
+			goto out;
+	}
+
+	__dev_status(md, param);
+
+out:
+	dm_put(md);
+
+	return r;
+}
+
+static int do_resume(struct dm_ioctl *param)
+{
+	int r = 0;
+	unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
+	struct hash_cell *hc;
+	struct mapped_device *md;
+	struct dm_table *new_map, *old_map = NULL;
+
+	down_write(&_hash_lock);
+
+	hc = __find_device_hash_cell(param);
+	if (!hc) {
+		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	md = hc->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 (param->flags & DM_SKIP_LOCKFS_FLAG)
+			suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
+		if (param->flags & DM_NOFLUSH_FLAG)
+			suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
+		if (!dm_suspended_md(md))
+			dm_suspend(md, suspend_flags);
+
+		old_map = dm_swap_table(md, new_map);
+		if (IS_ERR(old_map)) {
+			dm_sync_table(md);
+			dm_table_destroy(new_map);
+			dm_put(md);
+			return PTR_ERR(old_map);
+		}
+
+		if (dm_table_get_mode(new_map) & FMODE_WRITE)
+			set_disk_ro(dm_disk(md), 0);
+		else
+			set_disk_ro(dm_disk(md), 1);
+	}
+
+	if (dm_suspended_md(md)) {
+		r = dm_resume(md);
+		if (!r && !dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr))
+			param->flags |= DM_UEVENT_GENERATED_FLAG;
+	}
+
+	/*
+	 * Since dm_swap_table synchronizes RCU, nobody should be in
+	 * read-side critical section already.
+	 */
+	if (old_map)
+		dm_table_destroy(old_map);
+
+	if (!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 do_suspend(param);
+
+	return do_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)
+{
+	struct mapped_device *md;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	__dev_status(md, param);
+	dm_put(md);
+
+	return 0;
+}
+
+/*
+ * 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;
+	unsigned status_flags = 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);
+		size_t l;
+
+		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);
+		if (remaining <= 0) {
+			param->flags |= DM_BUFFER_FULL_FLAG;
+			break;
+		}
+
+		/* Get the status/table string from the target driver */
+		if (ti->type->status) {
+			if (param->flags & DM_NOFLUSH_FLAG)
+				status_flags |= DM_STATUS_NOFLUSH_FLAG;
+			ti->type->status(ti, type, status_flags, outptr, remaining);
+		} else
+			outptr[0] = '\0';
+
+		l = strlen(outptr) + 1;
+		if (l == remaining) {
+			param->flags |= DM_BUFFER_FULL_FLAG;
+			break;
+		}
+
+		outptr += l;
+		used = param->data_start + (outptr - outbuf);
+
+		outptr = align_ptr(outptr);
+		spec->next = outptr - outbuf;
+	}
+
+	if (used)
+		param->data_size = used;
+
+	param->target_count = num_targets;
+}
+
+/*
+ * Wait for a device to report an event
+ */
+static int dev_wait(struct dm_ioctl *param, size_t param_size)
+{
+	int r = 0;
+	struct mapped_device *md;
+	struct dm_table *table;
+	int srcu_idx;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	/*
+	 * Wait for a notification event
+	 */
+	if (dm_wait_event(md, param->event_nr)) {
+		r = -ERESTARTSYS;
+		goto out;
+	}
+
+	/*
+	 * 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.
+	 */
+	__dev_status(md, param);
+
+	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
+	if (table)
+		retrieve_status(table, param, param_size);
+	dm_put_live_table(md, srcu_idx);
+
+out:
+	dm_put(md);
+
+	return r;
+}
+
+static inline fmode_t get_mode(struct dm_ioctl *param)
+{
+	fmode_t 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, *old_map = NULL;
+	struct mapped_device *md;
+	struct target_type *immutable_target_type;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	r = dm_table_create(&t, get_mode(param), param->target_count, md);
+	if (r)
+		goto err;
+
+	/* Protect md->type and md->queue against concurrent table loads. */
+	dm_lock_md_type(md);
+	r = populate_table(t, param, param_size);
+	if (r)
+		goto err_unlock_md_type;
+
+	immutable_target_type = dm_get_immutable_target_type(md);
+	if (immutable_target_type &&
+	    (immutable_target_type != dm_table_get_immutable_target_type(t))) {
+		DMWARN("can't replace immutable target type %s",
+		       immutable_target_type->name);
+		r = -EINVAL;
+		goto err_unlock_md_type;
+	}
+
+	if (dm_get_md_type(md) == DM_TYPE_NONE) {
+		/* Initial table load: acquire type of table. */
+		dm_set_md_type(md, dm_table_get_type(t));
+
+		/* setup md->queue to reflect md's type (may block) */
+		r = dm_setup_md_queue(md);
+		if (r) {
+			DMWARN("unable to set up device queue for new table.");
+			goto err_unlock_md_type;
+		}
+	} else if (dm_get_md_type(md) != dm_table_get_type(t)) {
+		DMWARN("can't change device type after initial table load.");
+		r = -EINVAL;
+		goto err_unlock_md_type;
+	}
+
+	dm_unlock_md_type(md);
+
+	/* stage inactive table */
+	down_write(&_hash_lock);
+	hc = dm_get_mdptr(md);
+	if (!hc || hc->md != md) {
+		DMWARN("device has been removed from the dev hash table.");
+		up_write(&_hash_lock);
+		r = -ENXIO;
+		goto err_destroy_table;
+	}
+
+	if (hc->new_map)
+		old_map = hc->new_map;
+	hc->new_map = t;
+	up_write(&_hash_lock);
+
+	param->flags |= DM_INACTIVE_PRESENT_FLAG;
+	__dev_status(md, param);
+
+	if (old_map) {
+		dm_sync_table(md);
+		dm_table_destroy(old_map);
+	}
+
+	dm_put(md);
+
+	return 0;
+
+err_unlock_md_type:
+	dm_unlock_md_type(md);
+err_destroy_table:
+	dm_table_destroy(t);
+err:
+	dm_put(md);
+
+	return r;
+}
+
+static int table_clear(struct dm_ioctl *param, size_t param_size)
+{
+	struct hash_cell *hc;
+	struct mapped_device *md;
+	struct dm_table *old_map = NULL;
+
+	down_write(&_hash_lock);
+
+	hc = __find_device_hash_cell(param);
+	if (!hc) {
+		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
+		up_write(&_hash_lock);
+		return -ENXIO;
+	}
+
+	if (hc->new_map) {
+		old_map = hc->new_map;
+		hc->new_map = NULL;
+	}
+
+	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
+
+	__dev_status(hc->md, param);
+	md = hc->md;
+	up_write(&_hash_lock);
+	if (old_map) {
+		dm_sync_table(md);
+		dm_table_destroy(old_map);
+	}
+	dm_put(md);
+
+	return 0;
+}
+
+/*
+ * 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_dev_internal *dd;
+	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_entry (dd, dm_table_get_devices(table), list)
+		deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev);
+
+	param->data_size = param->data_start + needed;
+}
+
+static int table_deps(struct dm_ioctl *param, size_t param_size)
+{
+	struct mapped_device *md;
+	struct dm_table *table;
+	int srcu_idx;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	__dev_status(md, param);
+
+	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
+	if (table)
+		retrieve_deps(table, param, param_size);
+	dm_put_live_table(md, srcu_idx);
+
+	dm_put(md);
+
+	return 0;
+}
+
+/*
+ * 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)
+{
+	struct mapped_device *md;
+	struct dm_table *table;
+	int srcu_idx;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	__dev_status(md, param);
+
+	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
+	if (table)
+		retrieve_status(table, param, param_size);
+	dm_put_live_table(md, srcu_idx);
+
+	dm_put(md);
+
+	return 0;
+}
+
+/*
+ * Process device-mapper dependent messages.  Messages prefixed with '@'
+ * are processed by the DM core.  All others are delivered to the target.
+ * Returns a number <= 1 if message was processed by device mapper.
+ * Returns 2 if message should be delivered to the target.
+ */
+static int message_for_md(struct mapped_device *md, unsigned argc, char **argv,
+			  char *result, unsigned maxlen)
+{
+	int r;
+
+	if (**argv != '@')
+		return 2; /* no '@' prefix, deliver to target */
+
+	if (!strcasecmp(argv[0], "@cancel_deferred_remove")) {
+		if (argc != 1) {
+			DMERR("Invalid arguments for @cancel_deferred_remove");
+			return -EINVAL;
+		}
+		return dm_cancel_deferred_remove(md);
+	}
+
+	r = dm_stats_message(md, argc, argv, result, maxlen);
+	if (r < 2)
+		return r;
+
+	DMERR("Unsupported message sent to DM core: %s", argv[0]);
+	return -EINVAL;
+}
+
+/*
+ * Pass a message to the target that's at the supplied device offset.
+ */
+static int target_message(struct dm_ioctl *param, size_t param_size)
+{
+	int r, argc;
+	char **argv;
+	struct mapped_device *md;
+	struct dm_table *table;
+	struct dm_target *ti;
+	struct dm_target_msg *tmsg = (void *) param + param->data_start;
+	size_t maxlen;
+	char *result = get_result_buffer(param, param_size, &maxlen);
+	int srcu_idx;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	if (tmsg < (struct dm_target_msg *) param->data ||
+	    invalid_str(tmsg->message, (void *) param + param_size)) {
+		DMWARN("Invalid target message parameters.");
+		r = -EINVAL;
+		goto out;
+	}
+
+	r = dm_split_args(&argc, &argv, tmsg->message);
+	if (r) {
+		DMWARN("Failed to split target message parameters");
+		goto out;
+	}
+
+	if (!argc) {
+		DMWARN("Empty message received.");
+		goto out_argv;
+	}
+
+	r = message_for_md(md, argc, argv, result, maxlen);
+	if (r <= 1)
+		goto out_argv;
+
+	table = dm_get_live_table(md, &srcu_idx);
+	if (!table)
+		goto out_table;
+
+	if (dm_deleting_md(md)) {
+		r = -ENXIO;
+		goto out_table;
+	}
+
+	ti = dm_table_find_target(table, tmsg->sector);
+	if (!dm_target_is_valid(ti)) {
+		DMWARN("Target message sector outside device.");
+		r = -EINVAL;
+	} else if (ti->type->message)
+		r = ti->type->message(ti, argc, argv);
+	else {
+		DMWARN("Target type does not support messages");
+		r = -EINVAL;
+	}
+
+ out_table:
+	dm_put_live_table(md, srcu_idx);
+ out_argv:
+	kfree(argv);
+ out:
+	if (r >= 0)
+		__dev_status(md, param);
+
+	if (r == 1) {
+		param->flags |= DM_DATA_OUT_FLAG;
+		if (dm_message_test_buffer_overflow(result, maxlen))
+			param->flags |= DM_BUFFER_FULL_FLAG;
+		else
+			param->data_size = param->data_start + strlen(result) + 1;
+		r = 0;
+	}
+
+	dm_put(md);
+	return r;
+}
+
+/*
+ * The ioctl parameter block consists of two parts, a dm_ioctl struct
+ * followed by a data buffer.  This flag is set if the second part,
+ * which has a variable size, is not used by the function processing
+ * the ioctl.
+ */
+#define IOCTL_FLAGS_NO_PARAMS	1
+
+/*-----------------------------------------------------------------
+ * Implementation of open/close/ioctl on the special char
+ * device.
+ *---------------------------------------------------------------*/
+static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
+{
+	static struct {
+		int cmd;
+		int flags;
+		ioctl_fn fn;
+	} _ioctls[] = {
+		{DM_VERSION_CMD, 0, NULL}, /* version is dealt with elsewhere */
+		{DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS, remove_all},
+		{DM_LIST_DEVICES_CMD, 0, list_devices},
+
+		{DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_create},
+		{DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_remove},
+		{DM_DEV_RENAME_CMD, 0, dev_rename},
+		{DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
+		{DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status},
+		{DM_DEV_WAIT_CMD, 0, dev_wait},
+
+		{DM_TABLE_LOAD_CMD, 0, table_load},
+		{DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear},
+		{DM_TABLE_DEPS_CMD, 0, table_deps},
+		{DM_TABLE_STATUS_CMD, 0, table_status},
+
+		{DM_LIST_VERSIONS_CMD, 0, list_versions},
+
+		{DM_TARGET_MSG_CMD, 0, target_message},
+		{DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry}
+	};
+
+	if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
+		return NULL;
+
+	*ioctl_flags = _ioctls[cmd].flags;
+	return _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 *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;
+}
+
+#define DM_PARAMS_KMALLOC	0x0001	/* Params alloced with kmalloc */
+#define DM_PARAMS_VMALLOC	0x0002	/* Params alloced with vmalloc */
+#define DM_WIPE_BUFFER		0x0010	/* Wipe input buffer before returning from ioctl */
+
+static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
+{
+	if (param_flags & DM_WIPE_BUFFER)
+		memset(param, 0, param_size);
+
+	if (param_flags & DM_PARAMS_KMALLOC)
+		kfree(param);
+	if (param_flags & DM_PARAMS_VMALLOC)
+		vfree(param);
+}
+
+static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
+		       int ioctl_flags,
+		       struct dm_ioctl **param, int *param_flags)
+{
+	struct dm_ioctl *dmi;
+	int secure_data;
+	const size_t minimum_data_size = sizeof(*param_kernel) - sizeof(param_kernel->data);
+
+	if (copy_from_user(param_kernel, user, minimum_data_size))
+		return -EFAULT;
+
+	if (param_kernel->data_size < minimum_data_size)
+		return -EINVAL;
+
+	secure_data = param_kernel->flags & DM_SECURE_DATA_FLAG;
+
+	*param_flags = secure_data ? DM_WIPE_BUFFER : 0;
+
+	if (ioctl_flags & IOCTL_FLAGS_NO_PARAMS) {
+		dmi = param_kernel;
+		dmi->data_size = minimum_data_size;
+		goto data_copied;
+	}
+
+	/*
+	 * Try to avoid low memory issues when a device is suspended.
+	 * Use kmalloc() rather than vmalloc() when we can.
+	 */
+	dmi = NULL;
+	if (param_kernel->data_size <= KMALLOC_MAX_SIZE) {
+		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
+		if (dmi)
+			*param_flags |= DM_PARAMS_KMALLOC;
+	}
+
+	if (!dmi) {
+		unsigned noio_flag;
+		noio_flag = memalloc_noio_save();
+		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
+		memalloc_noio_restore(noio_flag);
+		if (dmi)
+			*param_flags |= DM_PARAMS_VMALLOC;
+	}
+
+	if (!dmi) {
+		if (secure_data && clear_user(user, param_kernel->data_size))
+			return -EFAULT;
+		return -ENOMEM;
+	}
+
+	if (copy_from_user(dmi, user, param_kernel->data_size))
+		goto bad;
+
+data_copied:
+	/*
+	 * Abort if something changed the ioctl data while it was being copied.
+	 */
+	if (dmi->data_size != param_kernel->data_size) {
+		DMERR("rejecting ioctl: data size modified while processing parameters");
+		goto bad;
+	}
+
+	/* Wipe the user buffer so we do not return it to userspace */
+	if (secure_data && clear_user(user, param_kernel->data_size))
+		goto bad;
+
+	*param = dmi;
+	return 0;
+
+bad:
+	free_params(dmi, param_kernel->data_size, *param_flags);
+
+	return -EFAULT;
+}
+
+static int validate_params(uint cmd, struct dm_ioctl *param)
+{
+	/* Always clear this flag */
+	param->flags &= ~DM_BUFFER_FULL_FLAG;
+	param->flags &= ~DM_UEVENT_GENERATED_FLAG;
+	param->flags &= ~DM_SECURE_DATA_FLAG;
+	param->flags &= ~DM_DATA_OUT_FLAG;
+
+	/* Ignores parameters */
+	if (cmd == DM_REMOVE_ALL_CMD ||
+	    cmd == DM_LIST_DEVICES_CMD ||
+	    cmd == DM_LIST_VERSIONS_CMD)
+		return 0;
+
+	if ((cmd == DM_DEV_CREATE_CMD)) {
+		if (!*param->name) {
+			DMWARN("name not supplied when creating device");
+			return -EINVAL;
+		}
+	} else if ((*param->uuid && *param->name)) {
+		DMWARN("only supply one of name or uuid, 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(uint command, struct dm_ioctl __user *user)
+{
+	int r = 0;
+	int ioctl_flags;
+	int param_flags;
+	unsigned int cmd;
+	struct dm_ioctl *uninitialized_var(param);
+	ioctl_fn fn = NULL;
+	size_t input_param_size;
+	struct dm_ioctl param_kernel;
+
+	/* 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, &ioctl_flags);
+	if (!fn) {
+		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
+		return -ENOTTY;
+	}
+
+	/*
+	 * Copy the parameters into kernel space.
+	 */
+	r = copy_params(user, &param_kernel, ioctl_flags, &param, &param_flags);
+
+	if (r)
+		return r;
+
+	input_param_size = param->data_size;
+	r = validate_params(cmd, param);
+	if (r)
+		goto out;
+
+	param->data_size = sizeof(*param);
+	r = fn(param, input_param_size);
+
+	if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&
+	    unlikely(ioctl_flags & IOCTL_FLAGS_NO_PARAMS))
+		DMERR("ioctl %d tried to output some data but has IOCTL_FLAGS_NO_PARAMS set", cmd);
+
+	/*
+	 * Copy the results back to userland.
+	 */
+	if (!r && copy_to_user(user, param, param->data_size))
+		r = -EFAULT;
+
+out:
+	free_params(param, input_param_size, param_flags);
+	return r;
+}
+
+static long dm_ctl_ioctl(struct file *file, uint command, ulong u)
+{
+	return (long)ctl_ioctl(command, (struct dm_ioctl __user *)u);
+}
+
+#ifdef CONFIG_COMPAT
+static long dm_compat_ctl_ioctl(struct file *file, uint command, ulong u)
+{
+	return (long)dm_ctl_ioctl(file, command, (ulong) compat_ptr(u));
+}
+#else
+#define dm_compat_ctl_ioctl NULL
+#endif
+
+static const struct file_operations _ctl_fops = {
+	.open = nonseekable_open,
+	.unlocked_ioctl	 = dm_ctl_ioctl,
+	.compat_ioctl = dm_compat_ctl_ioctl,
+	.owner	 = THIS_MODULE,
+	.llseek  = noop_llseek,
+};
+
+static struct miscdevice _dm_misc = {
+	.minor		= MAPPER_CTRL_MINOR,
+	.name  		= DM_NAME,
+	.nodename	= DM_DIR "/" DM_CONTROL_NODE,
+	.fops  		= &_ctl_fops
+};
+
+MODULE_ALIAS_MISCDEV(MAPPER_CTRL_MINOR);
+MODULE_ALIAS("devname:" DM_DIR "/" DM_CONTROL_NODE);
+
+/*
+ * 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();
+}
+
+/**
+ * dm_copy_name_and_uuid - Copy mapped device name & uuid into supplied buffers
+ * @md: Pointer to mapped_device
+ * @name: Buffer (size DM_NAME_LEN) for name
+ * @uuid: Buffer (size DM_UUID_LEN) for uuid or empty string if uuid not defined
+ */
+int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
+{
+	int r = 0;
+	struct hash_cell *hc;
+
+	if (!md)
+		return -ENXIO;
+
+	mutex_lock(&dm_hash_cells_mutex);
+	hc = dm_get_mdptr(md);
+	if (!hc || hc->md != md) {
+		r = -ENXIO;
+		goto out;
+	}
+
+	if (name)
+		strcpy(name, hc->name);
+	if (uuid)
+		strcpy(uuid, hc->uuid ? : "");
+
+out:
+	mutex_unlock(&dm_hash_cells_mutex);
+
+	return r;
+}