[PATCH 0/2] nvme-passthru with vectored-io

[PATCH 0/2] nvme-passthru with vectored-io

[Kanchan Joshi]

NVMe passthru takes a single buffer pointer.
This enables using multiple buffers for passthru, similiar to
readv/writev.

First patch is prep, while second one adds vectored-io abililty to
NVME_IOCTL_IO64_CMD.

Kanchan Joshi (2):
  block: introduce and export blk_rq_map_user_vec
  nvme: add vectored-io support for user passthru

 block/blk-map.c                 | 19 +++++++++++++++++++
 drivers/nvme/host/ioctl.c       |  9 ++++++---
 include/linux/blk-mq.h          |  2 ++
 include/uapi/linux/nvme_ioctl.h |  4 ++++
 4 files changed, 31 insertions(+), 3 deletions(-)

-- 
2.25.1

[PATCH 1/2] block: introduce and export blk_rq_map_user_vec

[Kanchan Joshi]

Similiar to blk_rq_map_user except that it operates on iovec.
This is a prep patch.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 block/blk-map.c        | 19 +++++++++++++++++++
 include/linux/blk-mq.h |  2 ++
 2 files changed, 21 insertions(+)

diff --git a/block/blk-map.c b/block/blk-map.c
index 4526adde0156..7fe45df3e580 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -577,6 +577,25 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
 }
 EXPORT_SYMBOL(blk_rq_map_user);
 
+int blk_rq_map_user_vec(struct request_queue *q, struct request *rq,
+		    struct rq_map_data *map_data, void __user *uvec,
+		    unsigned long nr_vecs, gfp_t gfp_mask)
+{
+	struct iovec fast_iov[UIO_FASTIOV];
+	struct iovec *iov = fast_iov;
+	struct iov_iter iter;
+	int ret;
+
+	ret = import_iovec(rq_data_dir(rq), uvec, nr_vecs, UIO_FASTIOV, &iov, &iter);
+	if (unlikely(ret < 0))
+		return ret;
+	ret = blk_rq_map_user_iov(q, rq, NULL, &iter, gfp_mask);
+	kfree(iov);
+
+	return ret;
+}
+EXPORT_SYMBOL(blk_rq_map_user_vec);
+
 /**
  * blk_rq_unmap_user - unmap a request with user data
  * @bio:	       start of bio list
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index d319ffa59354..0fda666d2230 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -966,6 +966,8 @@ struct rq_map_data {
 
 int blk_rq_map_user(struct request_queue *, struct request *,
 		struct rq_map_data *, void __user *, unsigned long, gfp_t);
+int blk_rq_map_user_vec(struct request_queue *, struct request *,
+		struct rq_map_data *, void __user *, unsigned long, gfp_t);
 int blk_rq_map_user_iov(struct request_queue *, struct request *,
 		struct rq_map_data *, const struct iov_iter *, gfp_t);
 int blk_rq_unmap_user(struct bio *);
-- 
2.25.1

Re: [PATCH 1/2] block: introduce and export blk_rq_map_user_vec

[Christoph Hellwig]

On Thu, Jan 27, 2022 at 01:55:35PM +0530, Kanchan Joshi wrote:
> Similiar to blk_rq_map_user except that it operates on iovec.
> This is a prep patch.
> 
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
> ---
>  block/blk-map.c        | 19 +++++++++++++++++++
>  include/linux/blk-mq.h |  2 ++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/block/blk-map.c b/block/blk-map.c
> index 4526adde0156..7fe45df3e580 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -577,6 +577,25 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
>  }
>  EXPORT_SYMBOL(blk_rq_map_user);
>  
> +int blk_rq_map_user_vec(struct request_queue *q, struct request *rq,
> +		    struct rq_map_data *map_data, void __user *uvec,
> +		    unsigned long nr_vecs, gfp_t gfp_mask)
> +{
> +	struct iovec fast_iov[UIO_FASTIOV];
> +	struct iovec *iov = fast_iov;
> +	struct iov_iter iter;
> +	int ret;
> +
> +	ret = import_iovec(rq_data_dir(rq), uvec, nr_vecs, UIO_FASTIOV, &iov, &iter);
> +	if (unlikely(ret < 0))
> +		return ret;
> +	ret = blk_rq_map_user_iov(q, rq, NULL, &iter, gfp_mask);
> +	kfree(iov);
> +
> +	return ret;

I see very little point in adding this function vs just open coding it.

Also please don't add overly long lines.

Re: [PATCH 1/2] block: introduce and export blk_rq_map_user_vec

[Kanchan Joshi]

On Thu, Jan 27, 2022 at 2:57 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Thu, Jan 27, 2022 at 01:55:35PM +0530, Kanchan Joshi wrote:
> > Similiar to blk_rq_map_user except that it operates on iovec.
> > This is a prep patch.
> >
> > Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> > Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
> > ---
> >  block/blk-map.c        | 19 +++++++++++++++++++
> >  include/linux/blk-mq.h |  2 ++
> >  2 files changed, 21 insertions(+)
> >
> > diff --git a/block/blk-map.c b/block/blk-map.c
> > index 4526adde0156..7fe45df3e580 100644
> > --- a/block/blk-map.c
> > +++ b/block/blk-map.c
> > @@ -577,6 +577,25 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
> >  }
> >  EXPORT_SYMBOL(blk_rq_map_user);
> >
> > +int blk_rq_map_user_vec(struct request_queue *q, struct request *rq,
> > +                 struct rq_map_data *map_data, void __user *uvec,
> > +                 unsigned long nr_vecs, gfp_t gfp_mask)
> > +{
> > +     struct iovec fast_iov[UIO_FASTIOV];
> > +     struct iovec *iov = fast_iov;
> > +     struct iov_iter iter;
> > +     int ret;
> > +
> > +     ret = import_iovec(rq_data_dir(rq), uvec, nr_vecs, UIO_FASTIOV, &iov, &iter);
> > +     if (unlikely(ret < 0))
> > +             return ret;
> > +     ret = blk_rq_map_user_iov(q, rq, NULL, &iter, gfp_mask);
> > +     kfree(iov);
> > +
> > +     return ret;
>
> I see very little point in adding this function vs just open coding it.

Fine, I will kill this and open-code in nvme instead.


-- 
Kanchan

Re: [PATCH 1/2] block: introduce and export blk_rq_map_user_vec

[Chaitanya Kulkarni]

On 1/27/22 12:25 AM, Kanchan Joshi wrote:
> External email: Use caution opening links or attachments
> 
> 
> Similiar to blk_rq_map_user except that it operates on iovec.
> This is a prep patch.
> 
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
> ---

Did you run checkpatch.pl ?

[PATCH 2/2] nvme: add vectored-io support for user passthru

[Kanchan Joshi]

wire up support for passthru that takes an array of buffers (using
iovec). Enable it for NVME_IOCTL_IO64_CMD; same ioctl code to be used
with following differences -

1. NVME_IOVEC to be set as cmd.flags
2. cmd.addr, base addr of user iovec array
3. cmd.data_len, count of iovec array elements

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
---
 drivers/nvme/host/ioctl.c       | 9 ++++++---
 include/uapi/linux/nvme_ioctl.h | 4 ++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 22314962842d..3a896443e110 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -65,6 +65,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	struct bio *bio = NULL;
 	void *meta = NULL;
 	int ret;
+	u8 cmd_flags = cmd->common.flags;
 
 	req = nvme_alloc_request(q, cmd, 0);
 	if (IS_ERR(req))
@@ -75,7 +76,11 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	nvme_req(req)->flags |= NVME_REQ_USERCMD;
 
 	if (ubuffer && bufflen) {
-		ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
+		if (!(cmd_flags & NVME_IOVEC))
+			ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
+				GFP_KERNEL);
+		else
+			ret = blk_rq_map_user_vec(q, req, NULL, ubuffer, bufflen,
 				GFP_KERNEL);
 		if (ret)
 			goto out;
@@ -246,8 +251,6 @@ static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		return -EACCES;
 	if (copy_from_user(&cmd, ucmd, sizeof(cmd)))
 		return -EFAULT;
-	if (cmd.flags)
-		return -EINVAL;
 	if (!nvme_validate_passthru_nsid(ctrl, ns, cmd.nsid))
 		return -EINVAL;
 
diff --git a/include/uapi/linux/nvme_ioctl.h b/include/uapi/linux/nvme_ioctl.h
index d99b5a772698..d4999e3930f8 100644
--- a/include/uapi/linux/nvme_ioctl.h
+++ b/include/uapi/linux/nvme_ioctl.h
@@ -9,6 +9,10 @@
 
 #include <linux/types.h>
 
+enum nvme_ioc_flags {
+	NVME_IOVEC	= 1 << 0 /* vectored io */
+};
+
 struct nvme_user_io {
 	__u8	opcode;
 	__u8	flags;
-- 
2.25.1

Re: [PATCH 2/2] nvme: add vectored-io support for user passthru

[Christoph Hellwig]

On Thu, Jan 27, 2022 at 01:55:36PM +0530, Kanchan Joshi wrote:
> wire up support for passthru that takes an array of buffers (using
> iovec). Enable it for NVME_IOCTL_IO64_CMD; same ioctl code to be used
> with following differences -

Flags overloading for a completely different ABI is a bad idea.
Please add a separate ioctl instead.

Re: [PATCH 2/2] nvme: add vectored-io support for user passthru

[Kanchan Joshi]

On Thu, Jan 27, 2022 at 2:59 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Thu, Jan 27, 2022 at 01:55:36PM +0530, Kanchan Joshi wrote:
> > wire up support for passthru that takes an array of buffers (using
> > iovec). Enable it for NVME_IOCTL_IO64_CMD; same ioctl code to be used
> > with following differences -
>
> Flags overloading for a completely different ABI is a bad idea.
> Please add a separate ioctl instead.

Hope "NVME_IOCTL_IO64_VEC_CMD" sounds fine for the new one?

-- 
Kanchan

Re: [PATCH 2/2] nvme: add vectored-io support for user passthru

[Chaitanya Kulkarni]

Flags overloading for a completely different ABI is a bad idea.
>> Please add a separate ioctl instead.
> 
> Hope "NVME_IOCTL_IO64_VEC_CMD" sounds fine for the new one?
> 

sounds reasonable to me..

> --
> Kanchan
>