dm-ioctl.c

linux 内核源代码

/*
 * 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 <asm/uaccess.h>

#define DM_MSG_PREFIX "ioctl"
#define DM_DRIVER_EMAIL "[e-mail]"

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

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

static void dm_hash_remove_all(int keep_open_devices)
{
	int i, dev_skipped, dev_removed;
	struct hash_cell *hc;
	struct list_head *tmp, *n;

	down_write(&_hash_lock);

retry:
	dev_skipped = dev_removed = 0;
	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);

			if (keep_open_devices &&
			    dm_lock_for_deletion(hc->md)) {
				dev_skipped++;
				continue;
			}
			__hash_remove(hc);
			dev_removed = 1;
		}
	}

	/*
	 * Some mapped devices may be using other mapped devices, so if any
	 * still exist, repeat until we make no further progress.
	 */
	if (dev_skipped) {
		if (dev_removed)
			goto retry;

		DMWARN("remove_all left %d open device(s)", dev_skipped);
	}

	up_write(&_hash_lock);
}

static int dm_hash_rename(const char *old, const char *new)
{
	char *new_name, *old_name;
	struct hash_cell *hc;
	struct dm_table *table;

	/*
	 * duplicate new.
	 */
	new_name = kstrdup(new, GFP_KERNEL);
	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);
		dm_put(hc->md);
		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.
	 */
	list_del(&hc->name_list);
	old_name = hc->name;
	hc->name = new_name;
	list_add(&hc->name_list, _name_buckets + hash_str(new_name));

	/*
	 * Wake up any dm event waiters.
	 */
	table = dm_get_table(hc->md);
	if (table) {
		dm_table_event(table);
		dm_table_put(table);
	}

	dm_kobject_uevent(hc->md);

	dm_put(hc->md);
	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(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(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 += 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)