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From:   "Andreas Hindborg (Samsung)" <nmi@metaspace.dk>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Hans Holmberg <Hans.Holmberg@wdc.com>,
        Aravind Ramesh <Aravind.Ramesh@wdc.com>,
        Jens Axboe <axboe@kernel.dk>,
        "open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        Matias Bjorling <Matias.Bjorling@wdc.com>,
        open list <linux-kernel@vger.kernel.org>,
        Damien Le Moal <dlemoal@kernel.org>, gost.dev@samsung.com,
        Minwoo Im <minwoo.im.dev@gmail.com>
Subject: Re: [PATCH v4 4/4] ublk: add zone append
Date:   Thu, 29 Jun 2023 11:17:07 +0200
In-reply-to: <ZJzwcG2gIxXh8HbE@ovpn-8-18.pek2.redhat.com>
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Ming Lei <ming.lei@redhat.com> writes:

> On Wed, Jun 28, 2023 at 09:06:49PM +0200, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@samsung.com>
>>=20
>> Add zone append feature to ublk. This feature uses the `addr` field of `=
struct
>> ublksrv_io_cmd`. Therefore ublk must be used with the user copy
>> feature (UBLK_F_USER_COPY) for zone append to be available. Without this
>> feature, ublk will fail zone append requests.
>
> Given zone append is a must, please fail to add device in case of zoned
> and !user_copy, then we can make fast IO code path clean.

I will squash the patches and reject zone support if not user copy is
enabled =F0=9F=91=8D

>
>>=20
>> Suggested-by: Ming Lei <ming.lei@redhat.com>
>> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
>> ---
>>  drivers/block/ublk_drv-zoned.c | 11 +++++++++
>>  drivers/block/ublk_drv.c       | 43 ++++++++++++++++++++++++++++++----
>>  drivers/block/ublk_drv.h       |  1 +
>>  include/uapi/linux/ublk_cmd.h  |  3 ++-
>>  4 files changed, 52 insertions(+), 6 deletions(-)
>>=20
>> diff --git a/drivers/block/ublk_drv-zoned.c b/drivers/block/ublk_drv-zon=
ed.c
>> index ea86bf4b3681..007e8fc7ff25 100644
>> --- a/drivers/block/ublk_drv-zoned.c
>> +++ b/drivers/block/ublk_drv-zoned.c
>> @@ -16,6 +16,16 @@ void ublk_set_nr_zones(struct ublk_device *ub)
>>  		ub->ub_disk->nr_zones =3D p->dev_sectors / p->chunk_sectors;
>>  }
>>=20=20
>> +int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
>> +{
>> +	const struct ublk_param_zoned *p =3D &ub->params.zoned;
>> +
>> +	if (! p->max_zone_append_sectors)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>>  void ublk_dev_param_zoned_apply(struct ublk_device *ub)
>>  {
>>  	const struct ublk_param_zoned *p =3D &ub->params.zoned;
>> @@ -23,6 +33,7 @@ void ublk_dev_param_zoned_apply(struct ublk_device *ub)
>>  	if (ub->dev_info.flags & UBLK_F_ZONED) {
>>  		disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
>>  		disk_set_max_open_zones(ub->ub_disk, p->max_open_zones);
>> +		blk_queue_max_zone_append_sectors(ub->ub_disk->queue, p->max_zone_app=
end_sectors);
>>  	}
>>  }
>>=20=20
>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
>> index 88fa39853c61..6a949669b47e 100644
>> --- a/drivers/block/ublk_drv.c
>> +++ b/drivers/block/ublk_drv.c
>> @@ -107,6 +107,11 @@ struct ublk_uring_cmd_pdu {
>>   */
>>  #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
>>=20=20
>> +/*
>> + * Set when IO is Zone Append
>> + */
>> +#define UBLK_IO_FLAG_ZONE_APPEND 0x10
>> +
>>  struct ublk_io {
>>  	/* userspace buffer address from io cmd */
>>  	__u64	addr;
>> @@ -230,6 +235,8 @@ static void ublk_dev_param_discard_apply(struct ublk=
_device *ub)
>>=20=20
>>  static int ublk_validate_params(const struct ublk_device *ub)
>>  {
>> +	int ret =3D 0;
>> +
>>  	/* basic param is the only one which must be set */
>>  	if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
>>  		const struct ublk_param_basic *p =3D &ub->params.basic;
>> @@ -260,6 +267,13 @@ static int ublk_validate_params(const struct ublk_d=
evice *ub)
>>  	if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
>>  		return -EINVAL;
>>=20=20
>> +	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
>> +	    (ub->params.types & UBLK_PARAM_TYPE_ZONED)) {
>> +		ret =3D ublk_dev_param_zoned_validate(ub);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>>  	return 0;
>>  }
>>=20=20
>> @@ -690,6 +704,11 @@ static blk_status_t ublk_setup_iod(struct ublk_queu=
e *ubq, struct request *req)
>>  			return BLK_STS_IOERR;
>>  		}
>>  	case REQ_OP_ZONE_APPEND:
>> +		if (!(ubq->dev->dev_info.flags & UBLK_F_USER_COPY))
>> +			return BLK_STS_IOERR;
>> +		ublk_op =3D UBLK_IO_OP_ZONE_APPEND;
>> +		io->flags |=3D UBLK_IO_FLAG_ZONE_APPEND;
>> +		break;
>>  	case REQ_OP_ZONE_RESET_ALL:
>>  	case REQ_OP_DRV_OUT:
>>  		/* We do not support zone append or reset_all yet */
>> @@ -1112,6 +1131,12 @@ static void ublk_commit_completion(struct ublk_de=
vice *ub,
>>  	/* find the io request and complete */
>>  	req =3D blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
>>=20=20
>> +	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED)) {
>> +		if (io->flags & UBLK_IO_FLAG_ZONE_APPEND)
>> +			req->__sector =3D ub_cmd->addr;
>> +		io->flags &=3D ~UBLK_IO_FLAG_ZONE_APPEND;
>> +	}
>> +
>>  	if (req && likely(!blk_should_fake_timeout(req->q)))
>>  		ublk_put_req_ref(ubq, req);
>>  }
>> @@ -1411,7 +1436,8 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd=
 *cmd,
>>  			^ (_IOC_NR(cmd_op) =3D=3D UBLK_IO_NEED_GET_DATA))
>>  		goto out;
>>=20=20
>> -	if (ublk_support_user_copy(ubq) && ub_cmd->addr) {
>> +	if (ublk_support_user_copy(ubq) &&
>> +	    !(io->flags & UBLK_IO_FLAG_ZONE_APPEND) && ub_cmd->addr) {
>>  		ret =3D -EINVAL;
>>  		goto out;
>>  	}
>> @@ -1534,11 +1560,14 @@ static inline bool ublk_check_ubuf_dir(const str=
uct request *req,
>>  		int ubuf_dir)
>>  {
>>  	/* copy ubuf to request pages */
>> -	if (req_op(req) =3D=3D REQ_OP_READ && ubuf_dir =3D=3D ITER_SOURCE)
>> +	if ((req_op(req) =3D=3D REQ_OP_READ || req_op(req) =3D=3D REQ_OP_DRV_I=
N) &&
>> +	    ubuf_dir =3D=3D ITER_SOURCE)
>>  		return true;
>>=20=20
>>  	/* copy request pages to ubuf */
>> -	if (req_op(req) =3D=3D REQ_OP_WRITE && ubuf_dir =3D=3D ITER_DEST)
>> +	if ((req_op(req) =3D=3D REQ_OP_WRITE ||
>> +	     req_op(req) =3D=3D REQ_OP_ZONE_APPEND) &&
>> +	    ubuf_dir =3D=3D ITER_DEST)
>>  		return true;
>>=20=20
>>  	return false;
>> @@ -1867,6 +1896,12 @@ static int ublk_ctrl_start_dev(struct ublk_device=
 *ub, struct io_uring_cmd *cmd)
>>  	ub->dev_info.ublksrv_pid =3D ublksrv_pid;
>>  	ub->ub_disk =3D disk;
>>=20=20
>> +	ub->dev_info.state =3D UBLK_S_DEV_LIVE;
>
> I guess the above line change isn't necessary?

It needs to go before the call to `ublk_revalidate_disk_zones()` because
that does IO to the disk in the form of a call to `report_zones()`. So I
can move it down a little bit.

Best regards,
Andreas