dm table: add always writeable feature
Add a target feature flag DM_TARGET_ALWAYS_WRITEABLE to indicate that a target
does not support read-only mode.
The initial implementation of the thin provisioning target uses 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 2ec3482..9917141 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -774,6 +774,12 @@
t->singleton = 1;
}
+ if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {
+ DMERR("%s: target type %s may not be included in read-only tables",
+ dm_device_name(t->md), type);
+ return -EINVAL;
+ }
+
tgt->table = t;
tgt->begin = start;
tgt->len = len;