To test the REQ_OP_WRITE_ZEROES command and fatal signal handling in
the code path starting from blkdev_issue_zeroout(), add a new module
parameter when null_blk module is loaded in non-memory-backed mode.
Disable REQ_OP_WRITE_ZEROES by default to retain the existing behavior.
without this patch :-
linux-block (for-next) # modprobe null_blk
linux-block (for-next) # blkdiscard -z -o 0 -l 40960 /dev/nullb0
linux-block (for-next) # dmesg -c
[24977.282226] null_blk: null_process_cmd 1337 WRITE
with this patch :-
linux-block (for-next) # modprobe null_blk write_zeroes=1
linux-block (for-next) # blkdiscard -z -o 0 -l 40960 /dev/nullb0
linux-block (for-next) # dmesg -c
[25009.164341] null_blk: null_process_cmd 1337 WRITE_ZEROES
Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
---
drivers/block/null_blk/main.c | 14 ++++++++++++--
drivers/block/null_blk/null_blk.h | 1 +
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 71c39bcd872c..b454f6e6c60a 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -221,6 +221,10 @@ static bool g_discard;
module_param_named(discard, g_discard, bool, 0444);
MODULE_PARM_DESC(discard, "Support discard operations (requires memory-backed null_blk device). Default: false");
+static bool g_write_zeroes;
+module_param_named(write_zeroes, g_write_zeroes, bool, 0444);
+MODULE_PARM_DESC(write_zeroes, "Support write-zeroes operations (requires non-memory-backed null_blk device). Default: false");
+
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)");
@@ -742,6 +746,7 @@ static struct nullb_device *null_alloc_dev(void)
dev->blocking = g_blocking;
dev->memory_backed = g_memory_backed;
dev->discard = g_discard;
+ dev->write_zeroes = g_write_zeroes;
dev->cache_size = g_cache_size;
dev->mbps = g_mbps;
dev->use_per_node_hctx = g_use_per_node_hctx;
@@ -1684,8 +1689,13 @@ static void null_del_dev(struct nullb *nullb)
dev->nullb = NULL;
}
-static void null_config_discard(struct nullb *nullb, struct queue_limits *lim)
+static void null_config_discard_write_zeroes(struct nullb *nullb,
+ struct queue_limits *lim)
{
+ /* REQ_OP_WRITE_ZEROES only supported in non memory backed mode */
+ if (!nullb->dev->memory_backed && nullb->dev->write_zeroes)
+ lim->max_write_zeroes_sectors = UINT_MAX >> 9;
+
if (nullb->dev->discard == false)
return;
@@ -1891,7 +1901,7 @@ static int null_add_dev(struct nullb_device *dev)
if (dev->virt_boundary)
lim.virt_boundary_mask = PAGE_SIZE - 1;
- null_config_discard(nullb, &lim);
+ null_config_discard_write_zeroes(nullb, &lim);
if (dev->zoned) {
rv = null_init_zoned_dev(dev, &lim);
if (rv)
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 477b97746823..8518b4bf2530 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -99,6 +99,7 @@ struct nullb_device {
bool power; /* power on/off the device */
bool memory_backed; /* if data is stored in memory */
bool discard; /* if support discard */
+ bool write_zeroes; /* if support write_zeroes */
bool zoned; /* if device is zoned */
bool virt_boundary; /* virtual boundary on/off for the device */
bool no_sched; /* no IO scheduler for the device */
--
2.40.0
