Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1416 insertions, 0 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
new file mode 100644
index 00000000000..ee3c869d970
--- /dev/null
+++ b/drivers/md/dm-ioctl.c
@@ -0,0 +1,1416 @@
+/*
+ * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ * Copyright (C) 2004 - 2005 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/devfs_fs_kernel.h>
+#include <linux/dm-ioctl.h>
+
+#include <asm/uaccess.h>
+
+#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;
+};
+
+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(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);
+}
+
+static int dm_hash_init(void)
+{
+	init_buckets(_name_buckets);
+	init_buckets(_uuid_buckets);
+	devfs_mk_dir(DM_DIR);
+	return 0;
+}
+
+static 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 hash_cell *hc;
+	unsigned int h = hash_str(str);
+
+	list_for_each_entry (hc, _name_buckets + h, name_list)
+		if (!strcmp(hc->name, str))
+			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))
+			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.
+ */
+static 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);
+	dm_set_mdptr(md, cell);
+	up_write(&_hash_lock);
+
+	return 0;
+
+ bad:
+	up_write(&_hash_lock);
+	free_cell(cell);
+	return -EBUSY;
+}
+
+static 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_set_mdptr(hc->md, NULL);
+	dm_put(hc->md);
+	if (hc->new_map)
+		dm_table_put(hc->new_map);
+	free_cell(hc);
+}
+
+static 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);
+}
+
+static 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) + 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(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 void list_version_get_needed(struct target_type *tt, void *needed_param)
+{
+    size_t *needed = needed_param;
+
+    *needed += strlen(tt->name);
+    *needed += sizeof(tt->version);
+    *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;
+}
+
+/*
+ * 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;
+
+	param->dev = huge_encode_dev(MKDEV(disk->major, disk->first_minor));
+
+	if (!(param->flags & DM_SKIP_BDGET_FLAG)) {
+		bdev = bdget_disk(disk, 0);
+		if (!bdev)
+			return -ENXIO;
+
+		/*
+		 * 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 = bdev->bd_openers;
+		bdput(bdev);
+	} else
+		param->open_count = -1;
+
+	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(huge_decode_dev(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 or dev.
+ */
+static inline struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
+{
+	if (*param->uuid)
+		return __get_uuid_cell(param->uuid);
+	else if (*param->name)
+		return __get_name_cell(param->name);
+	else
+		return dm_get_mdptr(huge_decode_dev(param->dev));
+}
+
+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;
+		dm_get(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;
+	}
+	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 do_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 do_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 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)
+{
+	int r;
+	struct mapped_device *md;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	r = __dev_status(md, param);
+	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);
+		if (remaining <= 0) {
+			param->flags |= DM_BUFFER_FULL_FLAG;
+			break;
+		}
+
+		/* 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);
+
+		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;
+	struct mapped_device *md;
+	struct dm_table *table;
+
+	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.
+	 */
+	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;
+}
+
+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), param->target_count);
+	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;
+	}
+
+	if (hc->new_map)
+		dm_table_put(hc->new_map);
+	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_dev *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->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;
+}
+
+/*
+ * 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;
+}
+
+/*
+ * 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;
+
+	md = find_device(param);
+	if (!md)
+		return -ENXIO;
+
+	r = __dev_status(md, param);
+	if (r)
+		goto out;
+
+	if (tmsg < (struct dm_target_msg *) (param + 1) ||
+	    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;
+	}
+
+	table = dm_get_table(md);
+	if (!table)
+		goto out_argv;
+
+	if (tmsg->sector >= dm_table_get_size(table)) {
+		DMWARN("Target message sector outside device.");
+		r = -EINVAL;
+		goto out_table;
+	}
+
+	ti = dm_table_find_target(table, tmsg->sector);
+	if (ti->type->message)
+		r = ti->type->message(ti, argc, argv);
+	else {
+		DMWARN("Target type does not support messages");
+		r = -EINVAL;
+	}
+
+ out_table:
+	dm_table_put(table);
+ out_argv:
+	kfree(argv);
+ out:
+	param->data_size = 0;
+	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},
+
+		{DM_LIST_VERSIONS_CMD, list_versions},
+
+		{DM_TARGET_MSG_CMD, target_message}
+	};
+
+	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 *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 *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 ||
+	    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(struct inode *inode, struct file *file,
+		     uint command, ulong u)
+{
+	int r = 0;
+	unsigned int cmd;
+	struct dm_ioctl *param;
+	struct dm_ioctl __user *user = (struct dm_ioctl __user *) 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();
+}