Re: [PATCH for-next] null_blk: add configfs variable shared_tags

[Chaitanya Kulkarni <chaitanyak@xxxxxxxxxx>]

On 1/15/24 19:39, Shin'ichiro Kawasaki wrote:
> Allow setting shared_tags through configfs, which could only be set as a
> module parameter. For that purpose, delay tag_set initialization from
> null_init() to null_add_dev(). Introduce the flag tag_set_initialized to
> manage the initialization status of tag_set.
>
> The following parameters can not be set through configfs yet:
>
>      timeout
>      requeue
>      init_hctx
>
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@xxxxxxx>
> ---
> This patch will allow running the blktests test cases block/010 and block/022
> using the built-in null_blk driver. Corresponding blktests side changes are
> drafted here [1].
>
> [1] https://github.com/kawasaki/blktests/tree/shared_tags
>
>   drivers/block/null_blk/main.c     | 38 ++++++++++++++++---------------
>   drivers/block/null_blk/null_blk.h |  1 +
>   2 files changed, 21 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 36755f263e8e..c3361e521564 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -69,6 +69,7 @@ static LIST_HEAD(nullb_list);
>   static struct mutex lock;
>   static int null_major;
>   static DEFINE_IDA(nullb_indexes);
> +static bool tag_set_initialized = false;

explicit initializing global bool to false really needed ?
unless I did something see [1].

-ck

[1]
nvme (nvme-6.8) # git diff drivers/block/null_blk/
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 9f7695f00c2d..12686aeaae38 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -68,6 +68,8 @@ struct nullb_page {
  static LIST_HEAD(nullb_list);
  static struct mutex lock;
  static int null_major;
+static bool abcd;
+static bool abcd_init = false;
  static DEFINE_IDA(nullb_indexes);
  static struct blk_mq_tag_set tag_set;

@@ -2280,6 +2282,7 @@ static int __init null_init(void)
         unsigned int i;
         struct nullb *nullb;

+       pr_info("%s %d abcd %d abcd_init %d\n", __func__, __LINE__, 
abcd, abcd_init);
         if (g_bs > PAGE_SIZE) {
                 pr_warn("invalid block size\n");
                 pr_warn("defaults block size to %lu\n", PAGE_SIZE);
nvme (nvme-6.8) # makej M=drivers/block/ clean
   CLEAN   drivers/block/Module.symvers
nvme (nvme-6.8) # makej M=drivers/block/
   CC [M]  drivers/block/floppy.o
   CC [M]  drivers/block/brd.o
   CC [M]  drivers/block/loop.o
   CC [M]  drivers/block/nbd.o
   CC [M]  drivers/block/virtio_blk.o
   CC [M]  drivers/block/xen-blkback/blkback.o
   CC [M]  drivers/block/xen-blkfront.o
   CC [M]  drivers/block/rbd.o
   CC [M]  drivers/block/xen-blkback/xenbus.o
   CC [M]  drivers/block/zram/zcomp.o
   CC [M]  drivers/block/mtip32xx/mtip32xx.o
   CC [M]  drivers/block/drbd/drbd_bitmap.o
   CC [M]  drivers/block/drbd/drbd_buildtag.o
   CC [M]  drivers/block/zram/zram_drv.o
   CC [M]  drivers/block/drbd/drbd_proc.o
   CC [M]  drivers/block/drbd/drbd_worker.o
   CC [M]  drivers/block/drbd/drbd_receiver.o
   CC [M]  drivers/block/null_blk/main.o
   CC [M]  drivers/block/drbd/drbd_req.o
   CC [M]  drivers/block/null_blk/trace.o
   CC [M]  drivers/block/drbd/drbd_actlog.o
   CC [M]  drivers/block/drbd/drbd_main.o
   CC [M]  drivers/block/null_blk/zoned.o
   CC [M]  drivers/block/drbd/drbd_strings.o
   CC [M]  drivers/block/drbd/drbd_nl.o
   CC [M]  drivers/block/drbd/drbd_interval.o
   CC [M]  drivers/block/drbd/drbd_state.o
   CC [M]  drivers/block/drbd/drbd_nla.o
   CC [M]  drivers/block/drbd/drbd_debugfs.o
   LD [M]  drivers/block/zram/zram.o
   LD [M]  drivers/block/xen-blkback/xen-blkback.o
   LD [M]  drivers/block/null_blk/null_blk.o
   LD [M]  drivers/block/drbd/drbd.o
   MODPOST drivers/block/Module.symvers
   CC [M]  drivers/block/floppy.mod.o
   CC [M]  drivers/block/brd.mod.o
   CC [M]  drivers/block/loop.mod.o
   CC [M]  drivers/block/nbd.mod.o
   CC [M]  drivers/block/virtio_blk.mod.o
   CC [M]  drivers/block/xen-blkfront.mod.o
   CC [M]  drivers/block/xen-blkback/xen-blkback.mod.o
   CC [M]  drivers/block/drbd/drbd.mod.o
   CC [M]  drivers/block/rbd.mod.o
   CC [M]  drivers/block/mtip32xx/mtip32xx.mod.o
   CC [M]  drivers/block/zram/zram.mod.o
   CC [M]  drivers/block/null_blk/null_blk.mod.o
   LD [M]  drivers/block/brd.ko
   LD [M]  drivers/block/xen-blkback/xen-blkback.ko
   LD [M]  drivers/block/drbd/drbd.ko
   LD [M]  drivers/block/loop.ko
   LD [M]  drivers/block/floppy.ko
   LD [M]  drivers/block/virtio_blk.ko
   LD [M]  drivers/block/null_blk/null_blk.ko
   LD [M]  drivers/block/rbd.ko
   LD [M]  drivers/block/mtip32xx/mtip32xx.ko
   LD [M]  drivers/block/zram/zram.ko
   LD [M]  drivers/block/nbd.ko
   LD [M]  drivers/block/xen-blkfront.ko
nvme (nvme-6.8) # insmod drivers/block/null_blk/null_blk.ko
nvme (nvme-6.8) # dmesg  -c
[23228.355423] null_blk: null_init 2285 abcd 0 abcd_init 0
[23228.357571] null_blk: disk nullb0 created
[23228.357574] null_blk: module loaded
nvme (nvme-6.8) #