[PATCH V4 7/8] null_blk: add param to set max write-zeroes sects

[Chaitanya Kulkarni]

Instead of hardcoding value for the maximum write-zeroes sector to
UINT_MAX >> 9, allow user to set the value with newly added module
parameter max_write_zeroes_sectors.

Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
---
 drivers/block/null_blk/main.c     | 10 +++++++++-
 drivers/block/null_blk/null_blk.h |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 2f787807cf63..8b7f42024f14 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -224,6 +224,10 @@ static bool g_write_zeroes;
 module_param_named(write_zeroes, g_write_zeroes, bool, 0444);
 MODULE_PARM_DESC(write_zeroes, "Support write-zeores operations. Default: false");
 
+static unsigned int g_max_write_zeroes_sectors = UINT_MAX >> 9;
+module_param_named(max_write_zeroes_sectors, g_max_write_zeroes_sectors, uint, 0444);
+MODULE_PARM_DESC(max_write_zeroes_sectors, "Maximum size of a REQ_OP_WRITE_ZEROES command (in 512B sectors).");
+
 static unsigned long g_cache_size;
 module_param_named(cache_size, g_cache_size, ulong, 0444);
 MODULE_PARM_DESC(mbps, "Cache size in MiB for memory-backed device. Default: 0 (none)");
@@ -425,6 +429,7 @@ NULLB_DEVICE_ATTR(queue_mode, uint, NULL);
 NULLB_DEVICE_ATTR(blocksize, uint, NULL);
 NULLB_DEVICE_ATTR(max_sectors, uint, NULL);
 NULLB_DEVICE_ATTR(max_discard_sectors, uint, NULL);
+NULLB_DEVICE_ATTR(max_write_zeroes_sectors, uint, NULL);
 NULLB_DEVICE_ATTR(irqmode, uint, NULL);
 NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL);
 NULLB_DEVICE_ATTR(index, uint, NULL);
@@ -550,6 +555,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
 	&nullb_device_attr_blocksize,
 	&nullb_device_attr_max_sectors,
 	&nullb_device_attr_max_discard_sectors,
+	&nullb_device_attr_max_write_zeroes_sectors,
 	&nullb_device_attr_irqmode,
 	&nullb_device_attr_hw_queue_depth,
 	&nullb_device_attr_index,
@@ -693,6 +699,7 @@ static struct nullb_device *null_alloc_dev(void)
 	dev->blocksize = g_bs;
 	dev->max_sectors = g_max_sectors;
 	dev->max_discard_sectors = g_max_discard_sectors;
+	dev->max_write_zeroes_sectors = g_max_write_zeroes_sectors;
 	dev->irqmode = g_irqmode;
 	dev->hw_queue_depth = g_hw_queue_depth;
 	dev->blocking = g_blocking;
@@ -1865,7 +1872,8 @@ static void null_config_write_zeroes(struct nullb *nullb)
 {
 	if (!nullb->dev->write_zeroes)
 		return;
-	blk_queue_max_write_zeroes_sectors(nullb->q, UINT_MAX >> 9);
+	blk_queue_max_write_zeroes_sectors(nullb->q,
+			nullb->dev->max_write_zeroes_sectors);
 }
 
 static const struct block_device_operations null_bio_ops = {
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 09940211326d..e692c2a7369e 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -103,6 +103,7 @@ struct nullb_device {
 	unsigned int blocksize; /* block size */
 	unsigned int max_sectors; /* Max sectors per command */
 	unsigned int max_discard_sectors; /* Max discard sectors per command */
+	unsigned int max_write_zeroes_sectors; /* Max write-zeroes sectors per command */
 	unsigned int irqmode; /* IRQ completion handler */
 	unsigned int hw_queue_depth; /* queue depth */
 	unsigned int index; /* index of the disk, only valid with a disk */
-- 
2.29.0