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-ioctl.c b/drivers/md/dm-ioctl.c
index 2e9a3ca..31c2dc2 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1215,6 +1215,7 @@
struct hash_cell *hc;
struct dm_table *t;
struct mapped_device *md;
+ struct target_type *immutable_target_type;
md = find_device(param);
if (!md)
@@ -1230,6 +1231,16 @@
goto out;
}
+ immutable_target_type = dm_get_immutable_target_type(md);
+ if (immutable_target_type &&
+ (immutable_target_type != dm_table_get_immutable_target_type(t))) {
+ DMWARN("can't replace immutable target type %s",
+ immutable_target_type->name);
+ dm_table_destroy(t);
+ r = -EINVAL;
+ goto out;
+ }
+
/* Protect md->type and md->queue against concurrent table loads. */
dm_lock_md_type(md);
if (dm_get_md_type(md) == DM_TYPE_NONE)