295 lines
6.5 KiB
C
295 lines
6.5 KiB
C
/*
|
|
* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
|
|
* Copyright (C) 2006-2008 Red Hat GmbH
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#include "dm-exception-store.h"
|
|
|
|
#include <linux/ctype.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/vmalloc.h>
|
|
#include <linux/slab.h>
|
|
|
|
#define DM_MSG_PREFIX "snapshot exception stores"
|
|
|
|
static LIST_HEAD(_exception_store_types);
|
|
static DEFINE_SPINLOCK(_lock);
|
|
|
|
static struct dm_exception_store_type *__find_exception_store_type(const char *name)
|
|
{
|
|
struct dm_exception_store_type *type;
|
|
|
|
list_for_each_entry(type, &_exception_store_types, list)
|
|
if (!strcmp(name, type->name))
|
|
return type;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct dm_exception_store_type *_get_exception_store_type(const char *name)
|
|
{
|
|
struct dm_exception_store_type *type;
|
|
|
|
spin_lock(&_lock);
|
|
|
|
type = __find_exception_store_type(name);
|
|
|
|
if (type && !try_module_get(type->module))
|
|
type = NULL;
|
|
|
|
spin_unlock(&_lock);
|
|
|
|
return type;
|
|
}
|
|
|
|
/*
|
|
* get_type
|
|
* @type_name
|
|
*
|
|
* Attempt to retrieve the dm_exception_store_type by name. If not already
|
|
* available, attempt to load the appropriate module.
|
|
*
|
|
* Exstore modules are named "dm-exstore-" followed by the 'type_name'.
|
|
* Modules may contain multiple types.
|
|
* This function will first try the module "dm-exstore-<type_name>",
|
|
* then truncate 'type_name' on the last '-' and try again.
|
|
*
|
|
* For example, if type_name was "clustered-shared", it would search
|
|
* 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.
|
|
*
|
|
* 'dm-exception-store-<type_name>' is too long of a name in my
|
|
* opinion, which is why I've chosen to have the files
|
|
* containing exception store implementations be 'dm-exstore-<type_name>'.
|
|
* If you want your module to be autoloaded, you will follow this
|
|
* naming convention.
|
|
*
|
|
* Returns: dm_exception_store_type* on success, NULL on failure
|
|
*/
|
|
static struct dm_exception_store_type *get_type(const char *type_name)
|
|
{
|
|
char *p, *type_name_dup;
|
|
struct dm_exception_store_type *type;
|
|
|
|
type = _get_exception_store_type(type_name);
|
|
if (type)
|
|
return type;
|
|
|
|
type_name_dup = kstrdup(type_name, GFP_KERNEL);
|
|
if (!type_name_dup) {
|
|
DMERR("No memory left to attempt load for \"%s\"", type_name);
|
|
return NULL;
|
|
}
|
|
|
|
while (request_module("dm-exstore-%s", type_name_dup) ||
|
|
!(type = _get_exception_store_type(type_name))) {
|
|
p = strrchr(type_name_dup, '-');
|
|
if (!p)
|
|
break;
|
|
p[0] = '\0';
|
|
}
|
|
|
|
if (!type)
|
|
DMWARN("Module for exstore type \"%s\" not found.", type_name);
|
|
|
|
kfree(type_name_dup);
|
|
|
|
return type;
|
|
}
|
|
|
|
static void put_type(struct dm_exception_store_type *type)
|
|
{
|
|
spin_lock(&_lock);
|
|
module_put(type->module);
|
|
spin_unlock(&_lock);
|
|
}
|
|
|
|
int dm_exception_store_type_register(struct dm_exception_store_type *type)
|
|
{
|
|
int r = 0;
|
|
|
|
spin_lock(&_lock);
|
|
if (!__find_exception_store_type(type->name))
|
|
list_add(&type->list, &_exception_store_types);
|
|
else
|
|
r = -EEXIST;
|
|
spin_unlock(&_lock);
|
|
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(dm_exception_store_type_register);
|
|
|
|
int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
|
|
{
|
|
spin_lock(&_lock);
|
|
|
|
if (!__find_exception_store_type(type->name)) {
|
|
spin_unlock(&_lock);
|
|
return -EINVAL;
|
|
}
|
|
|
|
list_del(&type->list);
|
|
|
|
spin_unlock(&_lock);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(dm_exception_store_type_unregister);
|
|
|
|
static int set_chunk_size(struct dm_exception_store *store,
|
|
const char *chunk_size_arg, char **error)
|
|
{
|
|
unsigned long chunk_size_ulong;
|
|
char *value;
|
|
|
|
chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
|
|
if (*chunk_size_arg == '\0' || *value != '\0' ||
|
|
chunk_size_ulong > UINT_MAX) {
|
|
*error = "Invalid chunk size";
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!chunk_size_ulong) {
|
|
store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
|
|
return 0;
|
|
}
|
|
|
|
return dm_exception_store_set_chunk_size(store,
|
|
(unsigned) chunk_size_ulong,
|
|
error);
|
|
}
|
|
|
|
int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
|
|
unsigned chunk_size,
|
|
char **error)
|
|
{
|
|
/* Check chunk_size is a power of 2 */
|
|
if (!is_power_of_2(chunk_size)) {
|
|
*error = "Chunk size is not a power of 2";
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Validate the chunk size against the device block size */
|
|
if (chunk_size %
|
|
(bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) ||
|
|
chunk_size %
|
|
(bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) {
|
|
*error = "Chunk size is not a multiple of device blocksize";
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
|
|
*error = "Chunk size is too high";
|
|
return -EINVAL;
|
|
}
|
|
|
|
store->chunk_size = chunk_size;
|
|
store->chunk_mask = chunk_size - 1;
|
|
store->chunk_shift = ffs(chunk_size) - 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
|
|
struct dm_snapshot *snap,
|
|
unsigned *args_used,
|
|
struct dm_exception_store **store)
|
|
{
|
|
int r = 0;
|
|
struct dm_exception_store_type *type = NULL;
|
|
struct dm_exception_store *tmp_store;
|
|
char persistent;
|
|
|
|
if (argc < 2) {
|
|
ti->error = "Insufficient exception store arguments";
|
|
return -EINVAL;
|
|
}
|
|
|
|
tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
|
|
if (!tmp_store) {
|
|
ti->error = "Exception store allocation failed";
|
|
return -ENOMEM;
|
|
}
|
|
|
|
persistent = toupper(*argv[0]);
|
|
if (persistent == 'P')
|
|
type = get_type("P");
|
|
else if (persistent == 'N')
|
|
type = get_type("N");
|
|
else {
|
|
ti->error = "Persistent flag is not P or N";
|
|
r = -EINVAL;
|
|
goto bad_type;
|
|
}
|
|
|
|
if (!type) {
|
|
ti->error = "Exception store type not recognised";
|
|
r = -EINVAL;
|
|
goto bad_type;
|
|
}
|
|
|
|
tmp_store->type = type;
|
|
tmp_store->snap = snap;
|
|
|
|
r = set_chunk_size(tmp_store, argv[1], &ti->error);
|
|
if (r)
|
|
goto bad;
|
|
|
|
r = type->ctr(tmp_store, 0, NULL);
|
|
if (r) {
|
|
ti->error = "Exception store type constructor failed";
|
|
goto bad;
|
|
}
|
|
|
|
*args_used = 2;
|
|
*store = tmp_store;
|
|
return 0;
|
|
|
|
bad:
|
|
put_type(type);
|
|
bad_type:
|
|
kfree(tmp_store);
|
|
return r;
|
|
}
|
|
EXPORT_SYMBOL(dm_exception_store_create);
|
|
|
|
void dm_exception_store_destroy(struct dm_exception_store *store)
|
|
{
|
|
store->type->dtr(store);
|
|
put_type(store->type);
|
|
kfree(store);
|
|
}
|
|
EXPORT_SYMBOL(dm_exception_store_destroy);
|
|
|
|
int dm_exception_store_init(void)
|
|
{
|
|
int r;
|
|
|
|
r = dm_transient_snapshot_init();
|
|
if (r) {
|
|
DMERR("Unable to register transient exception store type.");
|
|
goto transient_fail;
|
|
}
|
|
|
|
r = dm_persistent_snapshot_init();
|
|
if (r) {
|
|
DMERR("Unable to register persistent exception store type");
|
|
goto persistent_fail;
|
|
}
|
|
|
|
return 0;
|
|
|
|
persistent_fail:
|
|
dm_persistent_snapshot_exit();
|
|
transient_fail:
|
|
return r;
|
|
}
|
|
|
|
void dm_exception_store_exit(void)
|
|
{
|
|
dm_persistent_snapshot_exit();
|
|
dm_transient_snapshot_exit();
|
|
}
|