On Wed, May 19 2010 at 8:01am -0400,
Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
> On Wed, May 19, 2010 at 1:57 AM, Kiyoshi Ueda <k-ueda@xxxxxxxxxxxxx> wrote:
> > Also, your patch changes the queue configuration even when a table is
> > already active and used. (e.g. Loading bio-based table to a mapped_device
> > which is already active/used as request-based sets q->requst_fn in NULL.)
> > That could cause some critical problems.
>
> Yes, that is possible and I can add additional checks to prevent this.
> But this speaks to a more general problem with the existing DM code.
>
> dm_swap_table() has the negative check to prevent such table loads, e.g.:
> /* cannot change the device type, once a table is bound */
>
> This check should come during table_load, as part of
> dm_table_set_type(), rather than during table resume.
FYI, the following patch is the relevant portion of the v6 patch that
addresses the issue discussed above.
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 990cf17..62ebd94 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -782,6 +782,7 @@ int dm_table_set_type(struct dm_table *t)
{
unsigned i;
unsigned bio_based = 0, request_based = 0;
+ struct dm_table *live_table = NULL;
struct dm_target *tgt;
struct dm_dev_internal *dd;
struct list_head *devices;
@@ -803,7 +804,7 @@ int dm_table_set_type(struct dm_table *t)
if (bio_based) {
/* We must use this table as bio-based */
t->type = DM_TYPE_BIO_BASED;
- return 0;
+ goto finish;
}
BUG_ON(!request_based); /* No targets in this table */
@@ -831,6 +832,18 @@ int dm_table_set_type(struct dm_table *t)
t->type = DM_TYPE_REQUEST_BASED;
+finish:
+ /* cannot change the device type, once a table is bound */
+ live_table = dm_get_live_table(t->md);
+ if (live_table) {
+ if (dm_table_get_type(live_table) != dm_table_get_type(t)) {
+ DMWARN("can't change the device type after a table is bound");
+ dm_table_put(live_table);
+ return -EINVAL;
+ }
+ dm_table_put(live_table);
+ }
+
return 0;
}
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a47f0b8..923b662 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2470,13 +2470,6 @@ struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
goto out;
}
- /* cannot change the device type, once a table is bound */
- if (md->map &&
- (dm_table_get_type(md->map) != dm_table_get_type(table))) {
- DMWARN("can't change the device type after a table is bound");
- goto out;
- }
-
map = __bind(md, table, &limits);
out:
--
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