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)
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;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2fe3017..9836324 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -140,6 +140,8 @@
/* Protect queue and type against concurrent access. */
struct mutex type_lock;
+ struct target_type *immutable_target_type;
+
struct gendisk *disk;
char name[16];
@@ -2096,6 +2098,8 @@
write_lock_irqsave(&md->map_lock, flags);
old_map = md->map;
md->map = t;
+ md->immutable_target_type = dm_table_get_immutable_target_type(t);
+
dm_table_set_restrictions(t, q, limits);
if (merge_is_optional)
set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
@@ -2166,6 +2170,11 @@
return md->type;
}
+struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
+{
+ return md->immutable_target_type;
+}
+
/*
* Fully initialize a request-based queue (->elevator, ->request_fn, etc).
*/
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 6745dbd..b7dacd5 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -60,6 +60,7 @@
int dm_table_any_congested(struct dm_table *t, int bdi_bits);
int dm_table_any_busy_target(struct dm_table *t);
unsigned dm_table_get_type(struct dm_table *t);
+struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
bool dm_table_request_based(struct dm_table *t);
bool dm_table_supports_discards(struct dm_table *t);
int dm_table_alloc_md_mempools(struct dm_table *t);
@@ -72,6 +73,7 @@
void dm_unlock_md_type(struct mapped_device *md);
void dm_set_md_type(struct mapped_device *md, unsigned type);
unsigned dm_get_md_type(struct mapped_device *md);
+struct target_type *dm_get_immutable_target_type(struct mapped_device *md);
int dm_setup_md_queue(struct mapped_device *md);