[PATCH v4 07/10] dm: Add support for copy offload.

[Nitesh Shetty]

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

Signed-off-by: Nitesh Shetty <nj.shetty at samsung.com>
---
 drivers/md/dm-table.c         | 45 +++++++++++++++++++++++++++++++++++
 drivers/md/dm.c               |  6 +++++
 include/linux/device-mapper.h |  5 ++++
 3 files changed, 56 insertions(+)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index a37c7b763643..b7574f179ed6 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1893,6 +1893,38 @@ 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_offload_supported)
+			return false;
+
+		/*
+		 * target provides copy support (as implied by setting 'copy_offload_supported')
+		 * and it relies on _all_ data devices having copy support.
+		 */
+		if (ti->copy_offload_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)
 {
@@ -1981,6 +2013,19 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 		q->limits.discard_misaligned = 0;
 	}
 
+	if (!dm_table_supports_copy(t)) {
+		blk_queue_flag_clear(QUEUE_FLAG_COPY, q);
+		/* Must also clear copy limits... */
+		q->limits.max_copy_sectors = 0;
+		q->limits.max_hw_copy_sectors = 0;
+		q->limits.max_copy_range_sectors = 0;
+		q->limits.max_hw_copy_range_sectors = 0;
+		q->limits.max_copy_nr_ranges = 0;
+		q->limits.max_hw_copy_nr_ranges = 0;
+	} else {
+		blk_queue_flag_set(QUEUE_FLAG_COPY, q);
+	}
+
 	if (!dm_table_supports_secure_erase(t))
 		q->limits.max_secure_erase_sectors = 0;
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7e3b5bdcf520..b995de127093 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1595,6 +1595,12 @@ static blk_status_t __split_and_process_bio(struct clone_info *ci)
 	else if (unlikely(ci->is_abnormal_io))
 		return __process_abnormal_io(ci, ti);
 
+	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;
+	}
 	/*
 	 * Only support bio polling for normal IO, and the target io is
 	 * exactly inside the dm_io instance (verified in dm_poll_dm_io)
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index c2a3758c4aaa..9304e640c9b9 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -362,6 +362,11 @@ struct dm_target {
 	 * after returning DM_MAPIO_SUBMITTED from its map function.
 	 */
 	bool accounts_remapped_io:1;
+
+	/*
+	 * copy offload is supported
+	 */
+	bool copy_offload_supported:1;
 };
 
 void *dm_per_bio_data(struct bio *bio, size_t data_size);
-- 
2.35.1.500.gb896f729e2