[PATCH v20 01/12] block: Introduce queue limits and sysfs for copy-offload support

[Nitesh Shetty <nj.shetty@samsung.com>]

Add device limits as sysfs entries,
	- copy_max_bytes (RW)
	- copy_max_hw_bytes (RO)

Above limits help to split the copy payload in block layer.
copy_max_bytes: maximum total length of copy in single payload.
copy_max_hw_bytes: Reflects the device supported maximum limit.

Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 Documentation/ABI/stable/sysfs-block | 23 +++++++++++++++
 block/blk-settings.c                 | 34 ++++++++++++++++++++--
 block/blk-sysfs.c                    | 43 ++++++++++++++++++++++++++++
 include/linux/blkdev.h               | 14 +++++++++
 4 files changed, 112 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
index 831f19a32e08..52d8a253bf8e 100644
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -165,6 +165,29 @@ Description:
 		last zone of the device which may be smaller.
 
 
+What:		/sys/block/<disk>/queue/copy_max_bytes
+Date:		May 2024
+Contact:	linux-block@vger.kernel.org
+Description:
+		[RW] This is the maximum number of bytes that the block layer
+		will allow for a copy request. This is always smaller or
+		equal to the maximum size allowed by the hardware, indicated by
+		'copy_max_hw_bytes'. An attempt to set a value higher than
+		'copy_max_hw_bytes' will truncate this to 'copy_max_hw_bytes'.
+		Writing '0' to this file will disable offloading copies for this
+		device, instead copy is done via emulation.
+
+
+What:		/sys/block/<disk>/queue/copy_max_hw_bytes
+Date:		May 2024
+Contact:	linux-block@vger.kernel.org
+Description:
+		[RO] This is the maximum number of bytes that the hardware
+		will allow for single data copy request.
+		A value of 0 means that the device does not support
+		copy offload.
+
+
 What:		/sys/block/<disk>/queue/crypto/
 Date:		February 2022
 Contact:	linux-block@vger.kernel.org
diff --git a/block/blk-settings.c b/block/blk-settings.c
index a7fe8e90240a..67010ed82422 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -52,6 +52,9 @@ void blk_set_stacking_limits(struct queue_limits *lim)
 	lim->max_write_zeroes_sectors = UINT_MAX;
 	lim->max_zone_append_sectors = UINT_MAX;
 	lim->max_user_discard_sectors = UINT_MAX;
+	lim->max_copy_hw_sectors = UINT_MAX;
+	lim->max_copy_sectors = UINT_MAX;
+	lim->max_user_copy_sectors = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_set_stacking_limits);
 
@@ -219,6 +222,9 @@ static int blk_validate_limits(struct queue_limits *lim)
 		lim->misaligned = 0;
 	}
 
+	lim->max_copy_sectors =
+		min(lim->max_copy_hw_sectors, lim->max_user_copy_sectors);
+
 	return blk_validate_zoned_limits(lim);
 }
 
@@ -231,10 +237,11 @@ int blk_set_default_limits(struct queue_limits *lim)
 {
 	/*
 	 * Most defaults are set by capping the bounds in blk_validate_limits,
-	 * but max_user_discard_sectors is special and needs an explicit
-	 * initialization to the max value here.
+	 * but max_user_discard_sectors and max_user_copy_sectors are special
+	 * and needs an explicit initialization to the max value here.
 	 */
 	lim->max_user_discard_sectors = UINT_MAX;
+	lim->max_user_copy_sectors = UINT_MAX;
 	return blk_validate_limits(lim);
 }
 
@@ -316,6 +323,25 @@ void blk_queue_max_discard_sectors(struct request_queue *q,
 }
 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
 
+/*
+ * blk_queue_max_copy_hw_sectors - set max sectors for a single copy payload
+ * @q:	the request queue for the device
+ * @max_copy_sectors: maximum number of sectors to copy
+ */
+void blk_queue_max_copy_hw_sectors(struct request_queue *q,
+				   unsigned int max_copy_sectors)
+{
+	struct queue_limits *lim = &q->limits;
+
+	if (max_copy_sectors > (BLK_COPY_MAX_BYTES >> SECTOR_SHIFT))
+		max_copy_sectors = BLK_COPY_MAX_BYTES >> SECTOR_SHIFT;
+
+	lim->max_copy_hw_sectors = max_copy_sectors;
+	lim->max_copy_sectors =
+		min(max_copy_sectors, lim->max_user_copy_sectors);
+}
+EXPORT_SYMBOL_GPL(blk_queue_max_copy_hw_sectors);
+
 /**
  * blk_queue_max_secure_erase_sectors - set max sectors for a secure erase
  * @q:  the request queue for the device
@@ -633,6 +659,10 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 	t->max_segment_size = min_not_zero(t->max_segment_size,
 					   b->max_segment_size);
 
+	t->max_copy_sectors = min(t->max_copy_sectors, b->max_copy_sectors);
+	t->max_copy_hw_sectors = min(t->max_copy_hw_sectors,
+				     b->max_copy_hw_sectors);
+
 	t->misaligned |= b->misaligned;
 
 	alignment = queue_limit_alignment_offset(b, start);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index f0f9314ab65c..805c2b6b0393 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -205,6 +205,44 @@ static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *pag
 	return queue_var_show(0, page);
 }
 
+static ssize_t queue_copy_hw_max_show(struct request_queue *q, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)
+		       q->limits.max_copy_hw_sectors << SECTOR_SHIFT);
+}
+
+static ssize_t queue_copy_max_show(struct request_queue *q, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)
+		       q->limits.max_copy_sectors << SECTOR_SHIFT);
+}
+
+static ssize_t queue_copy_max_store(struct request_queue *q, const char *page,
+				    size_t count)
+{
+	unsigned long max_copy_bytes;
+	struct queue_limits lim;
+	ssize_t ret;
+	int err;
+
+	ret = queue_var_store(&max_copy_bytes, page, count);
+	if (ret < 0)
+		return ret;
+
+	if (max_copy_bytes & (queue_logical_block_size(q) - 1))
+		return -EINVAL;
+
+	blk_mq_freeze_queue(q);
+	lim = queue_limits_start_update(q);
+	lim.max_user_copy_sectors = max_copy_bytes >> SECTOR_SHIFT;
+	err = queue_limits_commit_update(q, &lim);
+	blk_mq_unfreeze_queue(q);
+
+	if (err)
+		return err;
+	return count;
+}
+
 static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
 {
 	return queue_var_show(0, page);
@@ -505,6 +543,9 @@ QUEUE_RO_ENTRY(queue_nr_zones, "nr_zones");
 QUEUE_RO_ENTRY(queue_max_open_zones, "max_open_zones");
 QUEUE_RO_ENTRY(queue_max_active_zones, "max_active_zones");
 
+QUEUE_RO_ENTRY(queue_copy_hw_max, "copy_max_hw_bytes");
+QUEUE_RW_ENTRY(queue_copy_max, "copy_max_bytes");
+
 QUEUE_RW_ENTRY(queue_nomerges, "nomerges");
 QUEUE_RW_ENTRY(queue_rq_affinity, "rq_affinity");
 QUEUE_RW_ENTRY(queue_poll, "io_poll");
@@ -618,6 +659,8 @@ static struct attribute *queue_attrs[] = {
 	&queue_discard_max_entry.attr,
 	&queue_discard_max_hw_entry.attr,
 	&queue_discard_zeroes_data_entry.attr,
+	&queue_copy_hw_max_entry.attr,
+	&queue_copy_max_entry.attr,
 	&queue_write_same_max_entry.attr,
 	&queue_write_zeroes_max_entry.attr,
 	&queue_zone_append_max_entry.attr,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index aefdda9f4ec7..109d9f905c3c 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -309,6 +309,10 @@ struct queue_limits {
 	unsigned int		discard_alignment;
 	unsigned int		zone_write_granularity;
 
+	unsigned int		max_copy_hw_sectors;
+	unsigned int		max_copy_sectors;
+	unsigned int		max_user_copy_sectors;
+
 	unsigned short		max_segments;
 	unsigned short		max_integrity_segments;
 	unsigned short		max_discard_segments;
@@ -933,6 +937,8 @@ void blk_queue_max_secure_erase_sectors(struct request_queue *q,
 		unsigned int max_sectors);
 extern void blk_queue_max_discard_sectors(struct request_queue *q,
 		unsigned int max_discard_sectors);
+extern void blk_queue_max_copy_hw_sectors(struct request_queue *q,
+					  unsigned int max_copy_sectors);
 extern void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
 		unsigned int max_write_same_sectors);
 extern void blk_queue_logical_block_size(struct request_queue *, unsigned int);
@@ -1271,6 +1277,14 @@ static inline unsigned int bdev_discard_granularity(struct block_device *bdev)
 	return bdev_get_queue(bdev)->limits.discard_granularity;
 }
 
+/* maximum copy offload length, this is set to 128MB based on current testing */
+#define BLK_COPY_MAX_BYTES		(1 << 27)
+
+static inline unsigned int bdev_max_copy_sectors(struct block_device *bdev)
+{
+	return bdev_get_queue(bdev)->limits.max_copy_sectors;
+}
+
 static inline unsigned int
 bdev_max_secure_erase_sectors(struct block_device *bdev)
 {
-- 
2.17.1