Re: [PATCH] null_blk: allow REQ_OP_ZONE_RESET_ALL to configure

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 10/6/22 14:05, Chaitanya Kulkarni wrote:
> For a Zoned Block Device zone reset all is emulated if underlaying
> device doesn't support REQ_OP_ZONE_RESET_ALL operation. In null_blk
> Zoned mode there is no way to test zone reset all emulation present in
> the block layer since we enable it by default :-
> 
> blkdev_zone_mgmt()
>  blkdev_zone_reset_all_emulation() <---
>  blkdev_zone_reset_all()
> 
> Add a module parameter zone_reset_all to enable or disable
> REQ_OP_ZONE_RESET_ALL, enable it by default to retain the existing
> behaviour.
> 
> Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
> ---
> # git log -1 
> commit 8ca0bd53a9c9e2f58c4fc9e38e3f5f82d26d3851 (HEAD -> for-next)
> Author: Chaitanya Kulkarni <kch@nvidia.com>
> Date:   Wed Oct 5 21:57:00 2022 -0700
> 
>     null_blk: allow REQ_OP_ZONE_RESET_ALL to configure
>     
>     For a Zoned Block Device zone reset all is emulated if underlaying
>     device doesn't support REQ_OP_ZONE_RESET_ALL operation. In null_blk
>     Zoned mode there is no way to test zone reset all emulation present in
>     the block layer since we enable it by default :-
>     
>     blkdev_zone_mgmt()
>      blkdev_zone_reset_all_emulation() <---
>      blkdev_zone_reset_all()
>     
>     Add a module parameter zone_reset_all to enable or disable
>     REQ_OP_ZONE_RESET_ALL, enable it by default to retain the existing
>     behaviour.
>     
>     Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
> # ./compile_nullb.sh 
> + umount /mnt/nullb0
> umount: /mnt/nullb0: not mounted.
> + rmdir 'config/nullb/nullb*'
> rmdir: failed to remove 'config/nullb/nullb*': No such file or directory
> + dmesg -c
> + modprobe -r null_blk
> + lsmod
> + grep null_blk
> ++ nproc
> + make -j 48 M=drivers/block modules
> + HOST=drivers/block/null_blk/
> ++ uname -r
> + HOST_DEST=/lib/modules/6.0.0-rc7blk+/kernel/drivers/block/null_blk/
> + cp drivers/block/null_blk//null_blk.ko /lib/modules/6.0.0-rc7blk+/kernel/drivers/block/null_blk//
> + ls -lrth /lib/modules/6.0.0-rc7blk+/kernel/drivers/block/null_blk//null_blk.ko
> -rw-r--r--. 1 root root 1.2M Oct  5 21:57 /lib/modules/6.0.0-rc7blk+/kernel/drivers/block/null_blk//null_blk.ko
> + sleep 1
> + dmesg -c
> # modprobe null_blk gb=1 zoned=1 zone_size=128 <---
> # lsblk
> NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
> sda       8:0    0   50G  0 disk 
> ├─sda1    8:1    0    1G  0 part /boot
> └─sda2    8:2    0   49G  0 part /home
> sdb       8:16   0  100G  0 disk /mnt/data
> sr0      11:0    1 1024M  0 rom  
> nullb0  250:0    0    1G  0 disk 
> zram0   251:0    0    8G  0 disk [SWAP]
> vda     252:0    0  512M  0 disk 
> nvme0n1 259:0    0    1G  0 disk 
> # blkzone reset /dev/nullb0
> # dmesg  -c
> [  397.079221] null_blk: disk nullb0 created
> [  397.079226] null_blk: module loaded
> [  406.626500] blkdev_zone_reset_all 237 <---
> # modprobe -r null_blk
> # 
> # 
> # 
> # modprobe null_blk gb=1 zoned=1 zone_size=128 zone_reset_all=0 <---
> # lsblk
> NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
> sda       8:0    0   50G  0 disk 
> ├─sda1    8:1    0    1G  0 part /boot
> └─sda2    8:2    0   49G  0 part /home
> sdb       8:16   0  100G  0 disk /mnt/data
> sr0      11:0    1 1024M  0 rom  
> nullb0  250:0    0    1G  0 disk 
> zram0   251:0    0    8G  0 disk [SWAP]
> vda     252:0    0  512M  0 disk 
> nvme0n1 259:0    0    1G  0 disk 
> # blkzone reset /dev/nullb0
> # dmesg  -c
> [  425.456187] null_blk: disk nullb0 created
> [  425.456192] null_blk: module loaded
> [  438.419529] blkdev_zone_reset_all_emulated 197 <---
> # modprobe -r null_blk
> # 
> ---
>  drivers/block/null_blk/main.c     | 5 +++++
>  drivers/block/null_blk/null_blk.h | 1 +
>  drivers/block/null_blk/zoned.c    | 3 ++-
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 8b7f42024f14..a0572e6c28ce 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -260,6 +260,10 @@ static unsigned int g_zone_max_active;
>  module_param_named(zone_max_active, g_zone_max_active, uint, 0444);
>  MODULE_PARM_DESC(zone_max_active, "Maximum number of active zones when block device is zoned. Default: 0 (no limit)");
>  
> +static bool g_zone_reset_all = true;
> +module_param_named(zone_reset_all, g_zone_reset_all, bool, 0444);

Nit: Why read-only ? You can make it writable without any issue, no ?

> +MODULE_PARM_DESC(zone_reset_all, "Allow REQ_OP_ZONE_RESET_ALL. Default: true");
> +
>  static struct nullb_device *null_alloc_dev(void);
>  static void null_free_dev(struct nullb_device *dev);
>  static void null_del_dev(struct nullb *nullb);
> @@ -715,6 +719,7 @@ static struct nullb_device *null_alloc_dev(void)
>  	dev->zone_nr_conv = g_zone_nr_conv;
>  	dev->zone_max_open = g_zone_max_open;
>  	dev->zone_max_active = g_zone_max_active;
> +	dev->zone_reset_all = g_zone_reset_all;
>  	dev->virt_boundary = g_virt_boundary;
>  	dev->no_sched = g_no_sched;
>  	dev->shared_tag_bitmap = g_shared_tag_bitmap;
> diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
> index e692c2a7369e..e7efe8de4ebf 100644
> --- a/drivers/block/null_blk/null_blk.h
> +++ b/drivers/block/null_blk/null_blk.h
> @@ -115,6 +115,7 @@ struct nullb_device {
>  	bool discard; /* if support discard */
>  	bool write_zeroes; /* if support write_zeroes */
>  	bool zoned; /* if device is zoned */
> +	bool zone_reset_all; /* if support REQ_OP_ZONE_RESET_ALL */
>  	bool virt_boundary; /* virtual boundary on/off for the device */
>  	bool no_sched; /* no IO scheduler for the device */
>  	bool shared_tag_bitmap; /* use hostwide shared tags */
> diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
> index 55a69e48ef8b..7310d1c3f9ec 100644
> --- a/drivers/block/null_blk/zoned.c
> +++ b/drivers/block/null_blk/zoned.c
> @@ -160,7 +160,8 @@ int null_register_zoned_dev(struct nullb *nullb)
>  	struct request_queue *q = nullb->q;
>  
>  	disk_set_zoned(nullb->disk, BLK_ZONED_HM);
> -	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
> +	if (dev->zone_reset_all)
> +		blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
>  	blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
>  
>  	if (queue_is_mq(q)) {

-- 
Damien Le Moal
Western Digital Research