[dm-devel] [PATCH v2 08/10] dm: Add support for copy offload.

[Nitesh Shetty]

Before enabling copy for dm target, check if underlaying devices and
dm target support copy. Avoid split happening inside dm target.
Fail early if the request needs split, currently spliting copy
request is not supported

Signed-off-by: Nitesh Shetty <nj.shetty at samsung.com>
---
 drivers/md/dm-table.c         | 43 +++++++++++++++++++++++++++++++++++
 drivers/md/dm.c               |  6 +++++
 include/linux/device-mapper.h |  5 ++++
 3 files changed, 54 insertions(+)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index e43096cfe9e2..cb5cdaf1d8b9 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1903,6 +1903,39 @@ static bool dm_table_supports_nowait(struct dm_table *t)
 	return true;
 }
 
+static int device_not_copy_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 !blk_queue_copy(q);
+}
+
+static bool dm_table_supports_copy(struct dm_table *t)
+{
+	struct dm_target *ti;
+	unsigned int i;
+
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		ti = dm_table_get_target(t, i);
+
+		if (!ti->copy_supported)
+			return false;
+
+		/*
+		 * Either the target provides copy support (as implied by setting
+		 * 'copy_supported') or it relies on _all_ data devices having
+		 * discard support.
+		 */
+		if (!ti->copy_supported &&
+		    (!ti->type->iterate_devices ||
+		     ti->type->iterate_devices(ti, device_not_copy_capable, NULL)))
+			return false;
+	}
+
+	return true;
+}
+
 static int device_not_discard_capable(struct dm_target *ti, struct dm_dev *dev,
 				      sector_t start, sector_t len, void *data)
 {
@@ -2000,6 +2033,16 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	} else
 		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
 
+	if (!dm_table_supports_copy(t)) {
+		blk_queue_flag_clear(QUEUE_FLAG_COPY, q);
+		/* Must also clear discard limits... */
+		q->limits.max_copy_sectors = 0;
+		q->limits.max_copy_range_sectors = 0;
+		q->limits.max_copy_nr_ranges = 0;
+	} else {
+		blk_queue_flag_set(QUEUE_FLAG_COPY, q);
+	}
+
 	if (dm_table_supports_secure_erase(t))
 		blk_queue_flag_set(QUEUE_FLAG_SECERASE, q);
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index fa596b654c99..2a6d55722139 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1420,6 +1420,12 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 	if (__process_abnormal_io(ci, ti, &r))
 		return r;
 
+	if ((unlikely(op_is_copy(ci->bio->bi_opf)) &&
+				max_io_len(ti, ci->sector) < ci->sector_count)) {
+		DMERR("%s: Error IO size(%u) is greater than maximum target size(%llu)\n",
+				__func__, ci->sector_count, max_io_len(ti, ci->sector));
+		return -EIO;
+	}
 	len = min_t(sector_t, max_io_len(ti, ci->sector), ci->sector_count);
 
 	r = __clone_and_map_data_bio(ci, ti, ci->sector, &len);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index b26fecf6c8e8..acfd4018125a 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -362,6 +362,11 @@ struct dm_target {
 	 * zone append operations using regular writes.
 	 */
 	bool emulate_zone_append:1;
+
+	/*
+	 * copy offload is supported
+	 */
+	bool copy_supported:1;
 };
 
 void *dm_per_bio_data(struct bio *bio, size_t data_size);
-- 
2.30.0-rc0