path: root/drivers/md/dm-ioctl.c

/*
 * 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;
};

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);

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;
}

/*-----------------------------------------------------------------
 * 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);
	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)
{
	struct dm_table *table;

	/* remove from the dev hash */
	list_del(&hc->uuid_list);
	list_del(&hc->name_list);
	dm_set_mdptr(hc->md, NULL);

	table = dm_get_table(hc->md);
	if (table