block: introduce a write_stream_granularity queue limit

Export the granularity that write streams should be discarded with,
as it is essential for making good use of them.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-5-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
index 8bbe1eca28df670813ae2dc4f230f3dd8836b91e..4ba771b56b3b5952cec4f1856c5ce5931a71d3bc 100644 (file)
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -555,6 +555,14 @@ Description:
                supported. If supported, valid values are 1 through
                max_write_streams, inclusive.
 
+What:          /sys/block/<disk>/queue/write_stream_granularity
+Date:          November 2024
+Contact:       linux-block@vger.kernel.org
+Description:
+               [RO] Granularity of a write stream in bytes.  The granularity
+               of a write stream is the size that should be discarded or
+               overwritten together to avoid write amplification in the device.
+
 What:          /sys/block/<disk>/queue/max_segments
 Date:          March 2010
 Contact:       linux-block@vger.kernel.org

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 5934150d4204b2affea9c02d1046c16477487187..386374ff655b9cb0e735c95c6d6aed27e7486108 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -135,6 +135,7 @@ QUEUE_SYSFS_LIMIT_SHOW(max_discard_segments)
 QUEUE_SYSFS_LIMIT_SHOW(max_integrity_segments)
 QUEUE_SYSFS_LIMIT_SHOW(max_segment_size)
 QUEUE_SYSFS_LIMIT_SHOW(max_write_streams)
+QUEUE_SYSFS_LIMIT_SHOW(write_stream_granularity)
 QUEUE_SYSFS_LIMIT_SHOW(logical_block_size)
 QUEUE_SYSFS_LIMIT_SHOW(physical_block_size)
 QUEUE_SYSFS_LIMIT_SHOW(chunk_sectors)
@@ -490,6 +491,7 @@ QUEUE_LIM_RO_ENTRY(queue_max_segments, "max_segments");
 QUEUE_LIM_RO_ENTRY(queue_max_integrity_segments, "max_integrity_segments");
 QUEUE_LIM_RO_ENTRY(queue_max_segment_size, "max_segment_size");
 QUEUE_LIM_RO_ENTRY(queue_max_write_streams, "max_write_streams");
+QUEUE_LIM_RO_ENTRY(queue_write_stream_granularity, "write_stream_granularity");
 QUEUE_RW_ENTRY(elv_iosched, "scheduler");
 
 QUEUE_LIM_RO_ENTRY(queue_logical_block_size, "logical_block_size");
@@ -645,6 +647,7 @@ static struct attribute *queue_attrs[] = {
        &queue_max_integrity_segments_entry.attr,
        &queue_max_segment_size_entry.attr,
        &queue_max_write_streams_entry.attr,
+       &queue_write_stream_granularity_entry.attr,
        &queue_hw_sector_size_entry.attr,
        &queue_logical_block_size_entry.attr,
        &queue_physical_block_size_entry.attr,

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 13e1426ad38da135d90fcdea57e479a0e35229c0..52b7a27c46e8a857adb8fd3554b636e744468531 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -405,6 +405,7 @@ struct queue_limits {
        unsigned short          max_discard_segments;
 
        unsigned short          max_write_streams;
+       unsigned int            write_stream_granularity;
 
        unsigned int            max_open_zones;
        unsigned int            max_active_zones;