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dm table: add immutable feature

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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>
This commit is contained in:
Alasdair G Kergon
2011-10-31 20:19:04 +00:00
parent cc6cbe141a
commit 36a0456fbf
6 changed files with 52 additions and 2 deletions
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21
drivers/md/dm-table.c
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@@ -54,6 +54,7 @@ struct dm_table {
sector_t *highs;
struct dm_target *targets;
struct target_type *immutable_target_type;
unsigned integrity_supported:1;
unsigned singleton:1;
@@ -780,6 +781,21 @@ int dm_table_add_target(struct dm_table *t, const char *type,
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 @@ unsigned dm_table_get_type(struct dm_table *t)
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;