Many but not all storage controllers require serialization of zoned writes.
Introduce a new request queue limit member variable
(driver_preserves_write_order) that allows block drivers to indicate that
the order of write commands is preserved and hence that serialization of
writes per zone is not required.
Make disk_set_zoned() set 'use_zone_write_lock' only if the block device
has zones and if the block driver does not preserve the order of write
requests.
Cc: Damien Le Moal <dlemoal@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
block/blk-settings.c | 7 +++++++
include/linux/blkdev.h | 10 ++++++++++
2 files changed, 17 insertions(+)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 0046b447268f..3a7748af1bef 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -56,6 +56,8 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->alignment_offset = 0;
lim->io_opt = 0;
lim->misaligned = 0;
+ lim->driver_preserves_write_order = false;
+ lim->use_zone_write_lock = false;
lim->zoned = BLK_ZONED_NONE;
lim->zone_write_granularity = 0;
lim->dma_alignment = 511;
@@ -685,6 +687,9 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
b->max_secure_erase_sectors);
t->zone_write_granularity = max(t->zone_write_granularity,
b->zone_write_granularity);
+ /* Request-based stacking drivers do not reorder requests. */
+ t->driver_preserves_write_order = b->driver_preserves_write_order;
+ t->use_zone_write_lock = b->use_zone_write_lock;
t->zoned = max(t->zoned, b->zoned);
return ret;
}
@@ -949,6 +954,8 @@ void disk_set_zoned(struct gendisk *disk, enum blk_zoned_model model)
}
q->limits.zoned = model;
+ q->limits.use_zone_write_lock = model != BLK_ZONED_NONE &&
+ !q->limits.driver_preserves_write_order;
if (model != BLK_ZONED_NONE) {
/*
* Set the zone write granularity to the device logical block
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 2f5371b8482c..2c090a28ec78 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -316,6 +316,16 @@ struct queue_limits {
unsigned char misaligned;
unsigned char discard_misaligned;
unsigned char raid_partial_stripes_expensive;
+ /*
+ * Whether or not the block driver preserves the order of write
+ * requests. Set by the block driver.
+ */
+ bool driver_preserves_write_order;
+ /*
+ * Whether or not zone write locking should be used. Set by
+ * disk_set_zoned().
+ */
+ bool use_zone_write_lock;
enum blk_zoned_model zoned;
/*
