dm thin: do not expose non-zero discard limits if discards disabled
Fix issue where the block layer would stack the discard limits of the
pool's data device even if the "ignore_discard" pool feature was
specified.
The pool and thin device(s) still had discards disabled because the
QUEUE_FLAG_DISCARD request_queue flag wasn't set. But to avoid user
confusion when "ignore_discard" is used: both the pool device and the
thin device(s) have zeroes for all discard limits.
Also, always set discard_zeroes_data_unsupported in targets because they
should never advertise the 'discard_zeroes_data' capability (even if the
pool's data device supports it).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ed06342..2c0cf51 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2095,6 +2095,7 @@
* them down to the data device. The thin device's discard
* processing will cause mappings to be removed from the btree.
*/
+ ti->discard_zeroes_data_unsupported = true;
if (pf.discard_enabled && pf.discard_passdown) {
ti->num_discard_bios = 1;
@@ -2104,7 +2105,6 @@
* thin devices' discard limits consistent).
*/
ti->discards_supported = true;
- ti->discard_zeroes_data_unsupported = true;
}
ti->private = pt;
@@ -2689,8 +2689,16 @@
* They get transferred to the live pool in bind_control_target()
* called from pool_preresume().
*/
- if (!pt->adjusted_pf.discard_enabled)
+ if (!pt->adjusted_pf.discard_enabled) {
+ /*
+ * Must explicitly disallow stacking discard limits otherwise the
+ * block layer will stack them if pool's data device has support.
+ * QUEUE_FLAG_DISCARD wouldn't be set but there is no way for the
+ * user to see that, so make sure to set all discard limits to 0.
+ */
+ limits->discard_granularity = 0;
return;
+ }
disable_passdown_if_not_supported(pt);
@@ -2826,10 +2834,10 @@
ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook);
/* In case the pool supports discards, pass them on. */
+ ti->discard_zeroes_data_unsupported = true;
if (tc->pool->pf.discard_enabled) {
ti->discards_supported = true;
ti->num_discard_bios = 1;
- ti->discard_zeroes_data_unsupported = true;
/* Discard bios must be split on a block boundary */
ti->split_discard_bios = true;
}