Best to disable WRITE SAME support for all targets and then require each
target to opt-in by setting 'num_write_same_requests' in the dm_target
structure.
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-table.c | 30 ++++++++++++++++++++++++++++++
include/linux/device-mapper.h | 6 ++++++
2 files changed, 36 insertions(+), 0 deletions(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 4c145fa..1ae337b 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1423,6 +1423,33 @@ static bool dm_table_all_devices_attribute(struct dm_table *t,
return 1;
}
+static int device_write_same_capable(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data)
+{
+ struct request_queue *q = bdev_get_queue(dev->bdev);
+
+ return q && q->limits.max_write_same_sectors;
+}
+
+static bool dm_table_supports_write_same(struct dm_table *t)
+{
+ struct dm_target *ti;
+ unsigned i = 0;
+
+ while (i < dm_table_get_num_targets(t)) {
+ ti = dm_table_get_target(t, i++);
+
+ if (!ti->num_write_same_requests)
+ continue;
+
+ if (!ti->type->iterate_devices ||
+ !ti->type->iterate_devices(ti, device_write_same_capable, NULL))
+ return 1;
+ }
+
+ return 0;
+}
+
void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
struct queue_limits *limits)
{
@@ -1454,6 +1481,9 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
else
queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);
+ if (!dm_table_supports_write_same(t))
+ q->limits.max_write_same_sectors = 0;
+
dm_table_set_integrity(t);
/*
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 2d65c70..072b72f 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -211,6 +211,12 @@ struct dm_target {
unsigned num_discard_requests;
/*
+ * The number of WRITE SAME requests that will be submitted to the target.
+ * The request number can be accessed with dm_bio_get_target_request_nr.
+ */
+ unsigned num_write_same_requests;
+
+ /*
* The minimum number of extra bytes allocated in each bio for the
* target to use. dm_per_bio_data returns the data location.
*/
--
1.7.1
--
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