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authorMike Snitzer <snitzer@redhat.com>2012-12-21 20:23:36 +0000
committerAlasdair G Kergon <agk@redhat.com>2012-12-21 20:23:36 +0000
commitd54eaa5a0fde0a202e4e91f200f818edcef15bee (patch)
treebb40893166dc8cd1d0f84c8087d021b66774a007
parent9c5091f2eeeffe5eca2ffe8a1bc28d312c8a5083 (diff)
downloadlinux-stericsson-d54eaa5a0fde0a202e4e91f200f818edcef15bee.tar.gz
dm: prepare to support WRITE SAME
Allow targets to opt in to WRITE SAME support by setting 'num_write_same_requests' in the dm_target structure. A dm device will only advertise WRITE SAME support if all its targets and all its underlying devices support it. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-table.c30
-rw-r--r--include/linux/device-mapper.h5
2 files changed, 34 insertions, 1 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index fa2955790031..6be58b696377 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1414,6 +1414,33 @@ static bool dm_table_all_devices_attribute(struct dm_table *t,
return 1;
}
+static int device_not_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)
+ return false;
+
+ if (!ti->type->iterate_devices ||
+ !ti->type->iterate_devices(ti, device_not_write_same_capable, NULL))
+ return false;
+ }
+
+ return true;
+}
+
void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
struct queue_limits *limits)
{
@@ -1445,7 +1472,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
else
queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);
- q->limits.max_write_same_sectors = 0;
+ 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 38d27a10aa5d..d1f6cd8486f2 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -205,6 +205,11 @@ struct dm_target {
*/
unsigned num_discard_requests;
+ /*
+ * The number of WRITE SAME requests that will be submitted to the target.
+ */
+ unsigned num_write_same_requests;
+
/* target specific data */
void *private;