block: introduce max_write_streams queue limit

Drivers with hardware that support write streams need a way to export how
many are available so applications can generically query this.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
[hch: renamed hints to streams, removed stacking]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-4-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 11545c9e2e93f2a15637cef6309d875c4ce8e385..8bbe1eca28df670813ae2dc4f230f3dd8836b91e 100644 (file)
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -547,6 +547,13 @@ Description:
                [RO] Maximum size in bytes of a single element in a DMA
                scatter/gather list.
 
+What:          /sys/block/<disk>/queue/max_write_streams
+Date:          November 2024
+Contact:       linux-block@vger.kernel.org
+Description:
+               [RO] Maximum number of write streams supported, 0 if not
+               supported. If supported, valid values are 1 through
+               max_write_streams, inclusive.
 
 What:          /sys/block/<disk>/queue/max_segments
 Date:          March 2010

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 01e0ead1327871fe84518d61e9aff64e6b796fb1..5934150d4204b2affea9c02d1046c16477487187 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -134,6 +134,7 @@ QUEUE_SYSFS_LIMIT_SHOW(max_segments)
 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(logical_block_size)
 QUEUE_SYSFS_LIMIT_SHOW(physical_block_size)
 QUEUE_SYSFS_LIMIT_SHOW(chunk_sectors)
@@ -488,6 +489,7 @@ QUEUE_LIM_RO_ENTRY(queue_max_hw_sectors, "max_hw_sectors_kb");
 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_RW_ENTRY(elv_iosched, "scheduler");
 
 QUEUE_LIM_RO_ENTRY(queue_logical_block_size, "logical_block_size");
@@ -642,6 +644,7 @@ static struct attribute *queue_attrs[] = {
        &queue_max_discard_segments_entry.attr,
        &queue_max_integrity_segments_entry.attr,
        &queue_max_segment_size_entry.attr,
+       &queue_max_write_streams_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 94323f303b37dc9da0d1590349a4e86ff89a4220..13e1426ad38da135d90fcdea57e479a0e35229c0 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -404,6 +404,8 @@ struct queue_limits {
        unsigned short          max_integrity_segments;
        unsigned short          max_discard_segments;
 
+       unsigned short          max_write_streams;
+
        unsigned int            max_open_zones;
        unsigned int            max_active_zones;
 
@@ -1270,6 +1272,13 @@ static inline unsigned int bdev_max_segments(struct block_device *bdev)
        return queue_max_segments(bdev_get_queue(bdev));
 }
 
+static inline unsigned short bdev_max_write_streams(struct block_device *bdev)
+{
+       if (bdev_is_partition(bdev))
+               return 0;
+       return bdev_limits(bdev)->max_write_streams;
+}
+
 static inline unsigned queue_logical_block_size(const struct request_queue *q)
 {
        return q->limits.logical_block_size;