A target, like the upcoming thin provisioning target, may want to allow
discards even if the underlying devices do not support them natively.
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-table.c | 4 ++++
include/linux/device-mapper.h | 6 ++++++
2 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index cb8380c..75b0430 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1354,6 +1354,10 @@ bool dm_table_supports_discards(struct dm_table *t)
while (i < dm_table_get_num_targets(t)) {
ti = dm_table_get_target(t, i++);
+ /* target supports discards even if underlying devices cannot */
+ if (ti->discards_supported)
+ return 1;
+
if (ti->type->iterate_devices &&
ti->type->iterate_devices(ti, device_discard_capable, NULL))
return 1;
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 32a4423..c9e7ff5 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -191,6 +191,12 @@ struct dm_target {
/* Used to provide an error string from the ctr */
char *error;
+
+ /*
+ * Enable discards even if the table's underlying devices
+ * do not have native discard support.
+ */
+ unsigned discards_supported:1;
};
/* Each target can link one of these into the table */
--
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