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>
diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index dccbfb0..8912a36 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -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;
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index aed1f11..3137715 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -39,6 +39,9 @@
*/
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 @@
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 @@
# 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 @@
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 */
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 0bbbe3b..e85b7a1 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -478,7 +478,7 @@
*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 @@
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 @@
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);
}
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index b558176..51bc4a7 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -23,7 +23,7 @@
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 @@
*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 @@
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);
}
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index dabd58e..be698f3 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -610,8 +610,6 @@
if (r)
goto bad3;
- s->type = persistent;
-
s->valid = 1;
s->active = 0;
atomic_set(&s->pending_exceptions_count, 0);
@@ -626,19 +624,15 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
* 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;
}
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index d9e62b4..627be0f 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -61,7 +61,7 @@
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;