Allow the memory_backed option to be set via a module parameter. Currently memory-backed null_blk devices can only be created using configfs. Having a module parameter makes it easier to create these devices. This patch was originally submitted by Akinobu Mita in 2020 but received no response. I modified the original patch to apply cleanly and reworded the documentation from the original patch. Originally-by: Akinobu Mita <akinobu.mita@xxxxxxxxx> Signed-off-by: Vincent Fu <vincent.fu@xxxxxxxxxxx> --- Documentation/block/null_blk.rst | 8 ++++++++ drivers/block/null_blk/main.c | 5 +++++ 2 files changed, 13 insertions(+) diff --git a/Documentation/block/null_blk.rst b/Documentation/block/null_blk.rst index edbbab2f1..618a491fa 100644 --- a/Documentation/block/null_blk.rst +++ b/Documentation/block/null_blk.rst @@ -72,6 +72,14 @@ submit_queues=[1..nr_cpus]: Default: 1 hw_queue_depth=[0..qdepth]: Default: 64 The hardware queue depth of the device. +memory_backed=[0/1]: Default: 0 + Whether or not to use a memory buffer to respond to IO requests + + = ============================================= + 0 Transfer no data in response to IO requests + 1 Use a memory buffer to respond to IO requests + = ============================================= + Multi-queue specific parameters ------------------------------- diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c index 539cfeac2..e97623c55 100644 --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -203,6 +203,10 @@ static int g_hw_queue_depth = 64; module_param_named(hw_queue_depth, g_hw_queue_depth, int, 0444); MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64"); +static bool g_memory_backed; +module_param_named(memory_backed, g_memory_backed, bool, 0444); +MODULE_PARM_DESC(memory_backed, "Create a memory-backed block device. Default: false"); + static bool g_use_per_node_hctx; module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, 0444); MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false"); @@ -656,6 +660,7 @@ static struct nullb_device *null_alloc_dev(void) dev->irqmode = g_irqmode; dev->hw_queue_depth = g_hw_queue_depth; dev->blocking = g_blocking; + dev->memory_backed = g_memory_backed; dev->use_per_node_hctx = g_use_per_node_hctx; dev->zoned = g_zoned; dev->zone_size = g_zone_size; -- 2.25.1
