dm: allow bio-based table to be upgraded to bio-based with DAX support

Allow table type DM_TYPE_BIO_BASED to extend with DM_TYPE_DAX_BIO_BASED
since DM_TYPE_DAX_BIO_BASED supports bio-based requests.

This is needed to allow a snapshot of an LV with DAX support to be
removed.  One of the intermediate table reloads that lvm2 does switches
from DM_TYPE_BIO_BASED to DM_TYPE_DAX_BIO_BASED.  No known reason to
disallow this so...

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 96df89a31f42..966eb4b61aed 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1267,6 +1267,15 @@ static int populate_table(struct dm_table *table,
         return dm_table_complete(table);
 }
 
+static bool is_valid_type(unsigned cur, unsigned new)
+{
+        if (cur == new ||
+            (cur == DM_TYPE_BIO_BASED && new == DM_TYPE_DAX_BIO_BASED))
+                return true;
+
+        return false;
+}
+
 static int table_load(struct dm_ioctl *param, size_t param_size)
 {
         int r;
@@ -1309,7 +1318,7 @@ static int table_load(struct dm_ioctl *param, size_t param_size)
                         DMWARN("unable to set up device queue for new table.");
                         goto err_unlock_md_type;
                 }
-        } else if (dm_get_md_type(md) != dm_table_get_type(t)) {
+        } else if (!is_valid_type(dm_get_md_type(md), dm_table_get_type(t))) {
                 DMWARN("can't change device type after initial table load.");
                 r = -EINVAL;
                 goto err_unlock_md_type;