dm: allow error target to replace bio-based and request-based targets
It may be useful to switch a request-based table to the "error" target.
Enhance the DM core to allow a hybrid target_type which is capable of
handling either bios (via .map) or requests (via .map_rq).
Add a request-based map function (.map_rq) to the "error" target_type;
making it DM's first hybrid target. Train dm_table_set_type() to prefer
the mapped device's established type (request-based or bio-based). If
the mapped device doesn't have an established type default to making the
table with the hybrid target(s) bio-based.
Tested 'dmsetup wipe_table' to work on both bio-based and request-based
devices.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index f221812..f309477 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -860,14 +860,17 @@
static int dm_table_set_type(struct dm_table *t)
{
unsigned i;
- unsigned bio_based = 0, request_based = 0;
+ unsigned bio_based = 0, request_based = 0, hybrid = 0;
struct dm_target *tgt;
struct dm_dev_internal *dd;
struct list_head *devices;
+ unsigned live_md_type;
for (i = 0; i < t->num_targets; i++) {
tgt = t->targets + i;
- if (dm_target_request_based(tgt))
+ if (dm_target_hybrid(tgt))
+ hybrid = 1;
+ else if (dm_target_request_based(tgt))
request_based = 1;
else
bio_based = 1;
@@ -879,6 +882,21 @@
}
}
+ if (hybrid && !bio_based && !request_based) {
+ /*
+ * The targets can work either way.
+ * Determine the type from the live device.
+ * Default to bio-based if device is new.
+ */
+ dm_lock_md_type(t->md);
+ live_md_type = dm_get_md_type(t->md);
+ dm_unlock_md_type(t->md);
+ if (live_md_type == DM_TYPE_REQUEST_BASED)
+ request_based = 1;
+ else
+ bio_based = 1;
+ }
+
if (bio_based) {
/* We must use this table as bio-based */
t->type = DM_TYPE_BIO_BASED;