dm table: add immutable feature
Introduce DM_TARGET_IMMUTABLE to indicate that the target type cannot be mixed
with any other target type, and once loaded into a device, it cannot be
replaced with a table containing a different type.
The thin provisioning pool device will use this.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 9917141..8e91321 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -54,6 +54,7 @@
sector_t *highs;
struct dm_target *targets;
+ struct target_type *immutable_target_type;
unsigned integrity_supported:1;
unsigned singleton:1;
@@ -780,6 +781,21 @@
return -EINVAL;
}
+ if (t->immutable_target_type) {
+ if (t->immutable_target_type != tgt->type) {
+ DMERR("%s: immutable target type %s cannot be mixed with other target types",
+ dm_device_name(t->md), t->immutable_target_type->name);
+ return -EINVAL;
+ }
+ } else if (dm_target_is_immutable(tgt->type)) {
+ if (t->num_targets) {
+ DMERR("%s: immutable target type %s cannot be mixed with other target types",
+ dm_device_name(t->md), tgt->type->name);
+ return -EINVAL;
+ }
+ t->immutable_target_type = tgt->type;
+ }
+
tgt->table = t;
tgt->begin = start;
tgt->len = len;
@@ -937,6 +953,11 @@
return t->type;
}
+struct target_type *dm_table_get_immutable_target_type(struct dm_table *t)
+{
+ return t->immutable_target_type;
+}
+
bool dm_table_request_based(struct dm_table *t)
{
return dm_table_get_type(t) == DM_TYPE_REQUEST_BASED;