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.

Reviewed-by: Hannes Reinecke <h...@suse.de>
Signed-off-by: Nitesh Shetty <nj.she...@samsung.com>
Signed-off-by: Kanchan Joshi <josh...@samsung.com>
Signed-off-by: Anuj Gupta <anuj2...@samsung.com>
---
 Documentation/ABI/stable/sysfs-block | 23 ++++++++++++++++++
 block/blk-settings.c                 | 24 +++++++++++++++++++
 block/blk-sysfs.c                    | 36 ++++++++++++++++++++++++++++
 include/linux/blkdev.h               | 13 ++++++++++
 4 files changed, 96 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-block 
b/Documentation/ABI/stable/sysfs-block
index c57e5b7cb532..1728b5ceabcb 100644
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -155,6 +155,29 @@ Description:
                last zone of the device which may be smaller.
 
 
+What:          /sys/block/<disk>/queue/copy_max_bytes
+Date:          August 2023
+Contact:       linux-bl...@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:          August 2023
+Contact:       linux-bl...@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-bl...@vger.kernel.org
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 0046b447268f..7c6aaa4df565 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -59,6 +59,8 @@ void blk_set_default_limits(struct queue_limits *lim)
        lim->zoned = BLK_ZONED_NONE;
        lim->zone_write_granularity = 0;
        lim->dma_alignment = 511;
+       lim->max_copy_hw_sectors = 0;
+       lim->max_copy_sectors = 0;
 }
 
 /**
@@ -82,6 +84,8 @@ void blk_set_stacking_limits(struct queue_limits *lim)
        lim->max_dev_sectors = UINT_MAX;
        lim->max_write_zeroes_sectors = UINT_MAX;
        lim->max_zone_append_sectors = UINT_MAX;
+       lim->max_copy_hw_sectors = UINT_MAX;
+       lim->max_copy_sectors = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_set_stacking_limits);
 
@@ -183,6 +187,22 @@ 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)
+{
+       if (max_copy_sectors > (COPY_MAX_BYTES >> SECTOR_SHIFT))
+               max_copy_sectors = COPY_MAX_BYTES >> SECTOR_SHIFT;
+
+       q->limits.max_copy_hw_sectors = max_copy_sectors;
+       q->limits.max_copy_sectors = max_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
@@ -578,6 +598,10 @@ 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 63e481262336..4840e21adefa 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -199,6 +199,37 @@ 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;
+       ssize_t ret = queue_var_store(&max_copy, page, count);
+
+       if (ret < 0)
+               return ret;
+
+       if (max_copy & (queue_logical_block_size(q) - 1))
+               return -EINVAL;
+
+       max_copy >>= SECTOR_SHIFT;
+       q->limits.max_copy_sectors = min_t(unsigned int, max_copy,
+                                          q->limits.max_copy_hw_sectors);
+
+       return count;
+}
+
 static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
 {
        return queue_var_show(0, page);
@@ -517,6 +548,9 @@ 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");
@@ -633,6 +667,8 @@ 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 e2418c7c16c5..6ab3b0d60315 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -309,6 +309,9 @@ struct queue_limits {
        unsigned int            discard_alignment;
        unsigned int            zone_write_granularity;
 
+       unsigned int            max_copy_hw_sectors;
+       unsigned int            max_copy_sectors;
+
        unsigned short          max_segments;
        unsigned short          max_integrity_segments;
        unsigned short          max_discard_segments;
@@ -892,6 +895,8 @@ extern void blk_queue_chunk_sectors(struct request_queue *, 
unsigned int);
 extern void blk_queue_max_segments(struct request_queue *, unsigned short);
 extern void blk_queue_max_discard_segments(struct request_queue *,
                unsigned short);
+extern void blk_queue_max_copy_hw_sectors(struct request_queue *q,
+                                         unsigned int max_copy_sectors);
 void blk_queue_max_secure_erase_sectors(struct request_queue *q,
                unsigned int max_sectors);
 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
@@ -1211,6 +1216,14 @@ 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 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)
 {
-- 
2.35.1.500.gb896f729e2

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