dm exception store: introduce registry

Move exception stores into a registry.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Jonathan Brassow 2009-04-02 19:55:31 +01:00 committed by Alasdair G Kergon
parent 7513c2a761
commit 493df71c64
6 changed files with 307 additions and 49 deletions

View File

@ -14,6 +14,168 @@
#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);
int dm_exception_store_create(const char *type_name,
struct dm_exception_store **store)
{
int r = 0;
struct dm_exception_store_type *type;
struct dm_exception_store *tmp_store;
tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
if (!tmp_store)
return -ENOMEM;
type = get_type(type_name);
if (!type) {
kfree(tmp_store);
return -EINVAL;
}
tmp_store->type = type;
r = type->ctr(tmp_store, 0, NULL);
if (r) {
put_type(type);
kfree(tmp_store);
return r;
}
*store = tmp_store;
return 0;
}
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;

View File

@ -39,6 +39,9 @@ struct dm_snap_exception {
*/
struct dm_exception_store;
struct dm_exception_store_type {
const char *name;
struct module *module;
int (*ctr) (struct dm_exception_store *store,
unsigned argc, char **argv);
@ -85,10 +88,13 @@ struct dm_exception_store_type {
void (*fraction_full) (struct dm_exception_store *store,
sector_t *numerator,
sector_t *denominator);
/* For internal device-mapper use only. */
struct list_head list;
};
struct dm_exception_store {
struct dm_exception_store_type type;
struct dm_exception_store_type *type;
struct dm_snapshot *snap;
@ -138,6 +144,13 @@ static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
# endif
int dm_exception_store_type_register(struct dm_exception_store_type *type);
int dm_exception_store_type_unregister(struct dm_exception_store_type *type);
int dm_exception_store_create(const char *type_name,
struct dm_exception_store **store);
void dm_exception_store_destroy(struct dm_exception_store *store);
int dm_exception_store_init(void);
void dm_exception_store_exit(void);
@ -150,8 +163,4 @@ void dm_persistent_snapshot_exit(void);
int dm_transient_snapshot_init(void);
void dm_transient_snapshot_exit(void);
int dm_create_persistent(struct dm_exception_store *store);
int dm_create_transient(struct dm_exception_store *store);
#endif /* _LINUX_DM_EXCEPTION_STORE */

View File

@ -478,7 +478,7 @@ static void persistent_fraction_full(struct dm_exception_store *store,
*denominator = get_dev_size(store->snap->cow->bdev);
}
static void persistent_destroy(struct dm_exception_store *store)
static void persistent_dtr(struct dm_exception_store *store)
{
struct pstore *ps = get_info(store);
@ -656,7 +656,8 @@ static void persistent_drop_snapshot(struct dm_exception_store *store)
DMWARN("write header failed");
}
int dm_create_persistent(struct dm_exception_store *store)
static int persistent_ctr(struct dm_exception_store *store,
unsigned argc, char **argv)
{
struct pstore *ps;
@ -683,23 +684,69 @@ int dm_create_persistent(struct dm_exception_store *store)
return -ENOMEM;
}
store->type.dtr = persistent_destroy;
store->type.read_metadata = persistent_read_metadata;
store->type.prepare_exception = persistent_prepare_exception;
store->type.commit_exception = persistent_commit_exception;
store->type.drop_snapshot = persistent_drop_snapshot;
store->type.fraction_full = persistent_fraction_full;
store->context = ps;
return 0;
}
static int persistent_status(struct dm_exception_store *store,
status_type_t status, char *result,
unsigned int maxlen)
{
int sz = 0;
return sz;
}
static struct dm_exception_store_type _persistent_type = {
.name = "persistent",
.module = THIS_MODULE,
.ctr = persistent_ctr,
.dtr = persistent_dtr,
.read_metadata = persistent_read_metadata,
.prepare_exception = persistent_prepare_exception,
.commit_exception = persistent_commit_exception,
.drop_snapshot = persistent_drop_snapshot,
.fraction_full = persistent_fraction_full,
.status = persistent_status,
};
static struct dm_exception_store_type _persistent_compat_type = {
.name = "P",
.module = THIS_MODULE,
.ctr = persistent_ctr,
.dtr = persistent_dtr,
.read_metadata = persistent_read_metadata,
.prepare_exception = persistent_prepare_exception,
.commit_exception = persistent_commit_exception,
.drop_snapshot = persistent_drop_snapshot,
.fraction_full = persistent_fraction_full,
.status = persistent_status,
};
int dm_persistent_snapshot_init(void)
{
return 0;
int r;
r = dm_exception_store_type_register(&_persistent_type);
if (r) {
DMERR("Unable to register persistent exception store type");
return r;
}
r = dm_exception_store_type_register(&_persistent_compat_type);
if (r) {
DMERR("Unable to register old-style persistent exception "
"store type");
dm_exception_store_type_unregister(&_persistent_type);
return r;
}
return r;
}
void dm_persistent_snapshot_exit(void)
{
dm_exception_store_type_unregister(&_persistent_type);
dm_exception_store_type_unregister(&_persistent_compat_type);
}

View File

@ -23,7 +23,7 @@ struct transient_c {
sector_t next_free;
};
static void transient_destroy(struct dm_exception_store *store)
static void transient_dtr(struct dm_exception_store *store)
{
kfree(store->context);
}
@ -67,17 +67,11 @@ static void transient_fraction_full(struct dm_exception_store *store,
*denominator = get_dev_size(store->snap->cow->bdev);
}
int dm_create_transient(struct dm_exception_store *store)
static int transient_ctr(struct dm_exception_store *store,
unsigned argc, char **argv)
{
struct transient_c *tc;
store->type.dtr = transient_destroy;
store->type.read_metadata = transient_read_metadata;
store->type.prepare_exception = transient_prepare_exception;
store->type.commit_exception = transient_commit_exception;
store->type.drop_snapshot = NULL;
store->type.fraction_full = transient_fraction_full;
tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
if (!tc)
return -ENOMEM;
@ -88,11 +82,62 @@ int dm_create_transient(struct dm_exception_store *store)
return 0;
}
static int transient_status(struct dm_exception_store *store,
status_type_t status, char *result,
unsigned maxlen)
{
int sz = 0;
return sz;
}
static struct dm_exception_store_type _transient_type = {
.name = "transient",
.module = THIS_MODULE,
.ctr = transient_ctr,
.dtr = transient_dtr,
.read_metadata = transient_read_metadata,
.prepare_exception = transient_prepare_exception,
.commit_exception = transient_commit_exception,
.fraction_full = transient_fraction_full,
.status = transient_status,
};
static struct dm_exception_store_type _transient_compat_type = {
.name = "N",
.module = THIS_MODULE,
.ctr = transient_ctr,
.dtr = transient_dtr,
.read_metadata = transient_read_metadata,
.prepare_exception = transient_prepare_exception,
.commit_exception = transient_commit_exception,
.fraction_full = transient_fraction_full,
.status = transient_status,
};
int dm_transient_snapshot_init(void)
{
return 0;
int r;
r = dm_exception_store_type_register(&_transient_type);
if (r) {
DMWARN("Unable to register transient exception store type");
return r;
}
r = dm_exception_store_type_register(&_transient_compat_type);
if (r) {
DMWARN("Unable to register old-style transient "
"exception store type");
dm_exception_store_type_unregister(&_transient_type);
return r;
}
return r;
}
void dm_transient_snapshot_exit(void)
{
dm_exception_store_type_unregister(&_transient_type);
dm_exception_store_type_unregister(&_transient_compat_type);
}

View File

@ -610,8 +610,6 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
if (r)
goto bad3;
s->type = persistent;
s->valid = 1;
s->active = 0;
atomic_set(&s->pending_exceptions_count, 0);
@ -626,19 +624,15 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad3;
}
s->store.snap = s;
if (persistent == 'P')
r = dm_create_persistent(&s->store);
else
r = dm_create_transient(&s->store);
r = dm_exception_store_create(argv[2], &s->store);
if (r) {
ti->error = "Couldn't create exception store";
r = -EINVAL;
goto bad4;
}
s->store->snap = s;
r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client);
if (r) {
ti->error = "Could not create kcopyd client";
@ -665,7 +659,8 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
spin_lock_init(&s->tracked_chunk_lock);
/* Metadata must only be loaded into one table at once */
r = s->store.type.read_metadata(&s->store, dm_add_exception, (void *)s);
r = s->store->type->read_metadata(s->store, dm_add_exception,
(void *)s);
if (r < 0) {
ti->error = "Failed to read snapshot metadata";
goto bad_load_and_register;
@ -700,7 +695,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
dm_kcopyd_client_destroy(s->kcopyd_client);
bad5:
s->store.type.dtr(&s->store);
s->store->type->dtr(s->store);
bad4:
exit_exception_table(&s->pending, pending_cache);
@ -725,7 +720,7 @@ static void __free_exceptions(struct dm_snapshot *s)
exit_exception_table(&s->pending, pending_cache);
exit_exception_table(&s->complete, exception_cache);
s->store.type.dtr(&s->store);
s->store->type->dtr(s->store);
}
static void snapshot_dtr(struct dm_target *ti)
@ -820,8 +815,8 @@ static void __invalidate_snapshot(struct dm_snapshot *s, int err)
else if (err == -ENOMEM)
DMERR("Invalidating snapshot: Unable to allocate exception.");
if (s->store.type.drop_snapshot)
s->store.type.drop_snapshot(&s->store);
if (s->store->type->drop_snapshot)
s->store->type->drop_snapshot(s->store);
s->valid = 0;
@ -943,8 +938,8 @@ static void copy_callback(int read_err, unsigned long write_err, void *context)
else
/* Update the metadata if we are persistent */
s->store.type.commit_exception(&s->store, &pe->e,
commit_callback, pe);
s->store->type->commit_exception(s->store, &pe->e,
commit_callback, pe);
}
/*
@ -1010,7 +1005,7 @@ __find_pending_exception(struct dm_snapshot *s,
atomic_set(&pe->ref_count, 0);
pe->started = 0;
if (s->store.type.prepare_exception(&s->store, &pe->e)) {
if (s->store->type->prepare_exception(s->store, &pe->e)) {
free_pending_exception(pe);
return NULL;
}
@ -1149,11 +1144,11 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
if (!snap->valid)
snprintf(result, maxlen, "Invalid");
else {
if (snap->store.type.fraction_full) {
if (snap->store->type->fraction_full) {
sector_t numerator, denominator;
snap->store.type.fraction_full(&snap->store,
&numerator,
&denominator);
snap->store->type->fraction_full(snap->store,
&numerator,
&denominator);
snprintf(result, maxlen, "%llu/%llu",
(unsigned long long)numerator,
(unsigned long long)denominator);
@ -1169,9 +1164,9 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
* to make private copies if the output is to
* make sense.
*/
snprintf(result, maxlen, "%s %s %c %llu",
snprintf(result, maxlen, "%s %s %s %llu",
snap->origin->name, snap->cow->name,
snap->type,
snap->store->type->name,
(unsigned long long)snap->chunk_size);
break;
}

View File

@ -61,7 +61,7 @@ struct dm_snapshot {
spinlock_t pe_lock;
/* The on disk metadata handler */
struct dm_exception_store store;
struct dm_exception_store *store;
struct dm_kcopyd_client *kcopyd_client;