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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;
}
/*-----------------------------------------------------------------
* 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 mapped_device *md;
void *mdptr = NULL;
if (*param->uuid)
return __get_uuid_cell(param->uuid);
if (*param->name)
return __get_name_cell(param->name);
md = dm_get_md(huge_decode_dev(param->dev));
if (!md)
goto out;
mdptr = dm_get_mdptr(md);
if (!mdptr)
dm_put(md);
out:
return mdptr;
}
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;
/*
* 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;
}
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;
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", indata,
indata + 1, indata + 2, indata + 3);
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);