dm-ioctl.c

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/*
 * 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 "[email protected]"

/*-----------------------------------------------------------------
 * 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(int keep_open_devices);

/*
 * 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(0);
}

/*-----------------------------------------------------------------
 * 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 void __hash_remove(struct hash_cell *hc)
{
    struct dm_table *table;

    /* 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);
    if (table) {
        dm_table_event(table);
        dm_table_put(table);
    }

    if (hc->new_map)
        dm_table_destroy(hc->new_map);
    dm_put(hc->md);
    free_cell(hc);
}

static void dm_hash_remove_all(int keep_open_devices)
{
    int i, dev_skipped;
    struct hash_cell *hc;
    struct mapped_device *md;

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)) {
                dm_put(md);
                dev_skipped++;
                continue;
            }

            __hash_remove(hc);

            up_write(&_hash_lock);

            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;

    /*
     * 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);
    if (table) {
        dm_table_event(table);
        dm_table_put(table);
    }

    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;
}

/*-----------------------------------------------------------------
 * 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(1);
    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_table_put, because dm_table_destroy
 * waits for this dm_table_put and could be called under this lock.
 */
static struct dm_table *dm_get_inactive_table(struct mapped_device *md)
{
    struct hash_cell *hc;
    struct dm_table *table = NULL;

    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;
    if (table)
        dm_table_get(table);

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)
{
    return (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) ?
        dm_get_inactive_table(md) : dm_get_live_table(md);
}

/*
 * 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;

    param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
              DM_ACTIVE_PRESENT_FLAG);

    if (dm_suspended_md(md))
        param->flags |= DM_SUSPEND_FLAG;

    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);
    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);
        }
        dm_table_put(table);

        param->flags |= DM_ACTIVE_PRESENT_FLAG;
    }

    if (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) {
        table = dm_get_inactive_table(md);
        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_table_put(table);
        }
    }
}

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;

    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);
    if (r) {
        DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
        up_write(&_hash_lock);
        dm_put(md);
        return r;
    }

    __hash_remove(hc);
    up_write(&_hash_lock);

    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) ||
        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_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;
    }

    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);

        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;
            if (ti->type->status(ti, type, status_flags, 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 = 0;
    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.
     */
    __dev_status(md, param);

    table = dm_get_live_or_inactive_table(md, param);
    if (table) {
        retrieve_status(table, param, param_size);
        dm_table_put(table);
    }

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;
    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 out;

    r = populate_table(t, param, param_size);
    if (r) {
        dm_table_destroy(t);
        goto out;
    }

    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);
        dm_table_destroy(t);
        r = -EINVAL;
        goto out;
    }

    /* Protect md->type and md->queue against concurrent table loads. */
    dm_lock_md_type(md);
    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));
    else if (dm_get_md_type(md) != dm_table_get_type(t)) {
        DMWARN("can't change device type after initial table load.");
        dm_table_destroy(t);
        dm_unlock_md_type(md);
        r = -EINVAL;
        goto out;
    }

    /* 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.");
        dm_table_destroy(t);
        dm_unlock_md_type(md);
        goto out;
    }
    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.");
        dm_table_destroy(t);
        up_write(&_hash_lock);
        r = -ENXIO;
        goto out;
    }

    if (hc->new_map)
        dm_table_destroy(hc->new_map);
    hc->new_map = t;
    up_write(&_hash_lock);

    param->flags |= DM_INACTIVE_PRESENT_FLAG;
    __dev_status(md, param);

out:
    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;

    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) {
        dm_table_destroy(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);
    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;

    md = find_device(param);
    if (!md)
        return -ENXIO;

    __dev_status(md, param);

    table = dm_get_live_or_inactive_table(md, param);
    if (table) {
        retrieve_deps(table, param, param_size);
        dm_table_put(table);
    }

    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;

    md = find_device(param);
    if (!md)
        return -ENXIO;

    __dev_status(md, param);

    table = dm_get_live_or_inactive_table(md, param);
    if (table) {
        retrieve_status(table, param, param_size);
        dm_table_put(table);
    }

    dm_put(md);

    return 0;
}

/*
 * 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;

    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;
    }

    table = dm_get_live_table(md);
    if (!table)
        goto out_argv;

    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_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},
        {DM_DEV_SET_GEOMETRY_CMD, dev_set_geometry}
    };

    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 int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param)
{
    struct dm_ioctl tmp, *dmi;
    int secure_data;

    if (copy_from_user(&tmp, user, sizeof(tmp) - sizeof(tmp.data)))
        return -EFAULT;

    if (tmp.data_size < (sizeof(tmp) - sizeof(tmp.data)))
        return -EINVAL;

    secure_data = tmp.flags & DM_SECURE_DATA_FLAG;

    dmi = vmalloc(tmp.data_size);
    if (!dmi) {
        if (secure_data && clear_user(user, tmp.data_size))
            return -EFAULT;
        return -ENOMEM;
    }

    if (copy_from_user(dmi, user, tmp.data_size))
        goto bad;

    /* Wipe the user buffer so we do not return it to userspace */
    if (secure_data && clear_user(user, tmp.data_size))
        goto bad;

    *param = dmi;
    return 0;

bad:
    if (secure_data)
        memset(dmi, 0, tmp.data_size);
    vfree(dmi);
    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;

    /* 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 wipe_buffer;
    unsigned int cmd;
    struct dm_ioctl *uninitialized_var(param);
    ioctl_fn fn = NULL;
    size_t input_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);

    current->flags &= ~PF_MEMALLOC;

    if (r)
        return r;

    input_param_size = param->data_size;
    wipe_buffer = param->flags & DM_SECURE_DATA_FLAG;

    r = validate_params(cmd, param);
    if (r)
        goto out;

    param->data_size = sizeof(*param);
    r = fn(param, input_param_size);

    /*
     * Copy the results back to userland.
     */
    if (!r && copy_to_user(user, param, param->data_size))
        r = -EFAULT;

out:
    if (wipe_buffer)
        memset(param, 0, input_param_size);

    vfree(param);
    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();
}

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;
}