[RFC PATCH v3 0/3] introduce io_uring_cmd_import_fixed_vec

[RFC PATCH v3 0/3] introduce io_uring_cmd_import_fixed_vec

[Sidong Yang]

This patche series introduce io_uring_cmd_import_vec. With this function,
Multiple fixed buffer could be used in uring cmd. It's vectored version
for io_uring_cmd_import_fixed(). Also this patch series includes a usage
for new api for encoded read/write in btrfs by using uring cmd.

There was approximately 10 percent of performance improvements through benchmark.
The benchmark code is in
https://github.com/SidongYang/btrfs-encoded-io-test/blob/main/main.c

./main -l
Elapsed time: 0.598997 seconds
./main -l -f
Elapsed time: 0.540332 seconds

v2:
 - don't export iou_vc, use bvec for btrfs
 - use io_is_compat for checking compat
 - reduce allocation/free for import fixed vec

v3:
 - add iou_vec cache in io_uring_cmd and use it
 - also encoded write fixed supported

Sidong Yang (3):
  io-uring/cmd: add iou_vec field for io_uring_cmd
  io-uring/cmd: introduce io_uring_cmd_import_fixed_vec
  btrfs: ioctl: introduce btrfs_uring_import_iovec()

 fs/btrfs/ioctl.c             | 32 +++++++++++++++++++++--------
 include/linux/io_uring/cmd.h | 15 ++++++++++++++
 io_uring/io_uring.c          |  2 +-
 io_uring/opdef.c             |  1 +
 io_uring/uring_cmd.c         | 39 ++++++++++++++++++++++++++++++++++++
 io_uring/uring_cmd.h         |  3 +++
 6 files changed, 83 insertions(+), 9 deletions(-)

-- 
2.43.0

[RFC PATCH v3 1/3] io-uring/cmd: add iou_vec field for io_uring_cmd

[Sidong Yang]

This patch adds iou_vec field for io_uring_cmd. Also it needs to be
cleanup for cache. It could be used in uring cmd api that imports
multiple fixed buffers.

Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
---
 include/linux/io_uring/cmd.h |  1 +
 io_uring/io_uring.c          |  2 +-
 io_uring/opdef.c             |  1 +
 io_uring/uring_cmd.c         | 20 ++++++++++++++++++++
 io_uring/uring_cmd.h         |  3 +++
 5 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 598cacda4aa3..74b9f0aec229 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -22,6 +22,7 @@ struct io_uring_cmd {
 struct io_uring_cmd_data {
 	void			*op_data;
 	struct io_uring_sqe	sqes[2];
+	struct iou_vec		iou_vec;
 };
 
 static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 5ff30a7092ed..55334fa53abf 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -289,7 +289,7 @@ static void io_free_alloc_caches(struct io_ring_ctx *ctx)
 	io_alloc_cache_free(&ctx->apoll_cache, kfree);
 	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
 	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
-	io_alloc_cache_free(&ctx->uring_cache, kfree);
+	io_alloc_cache_free(&ctx->uring_cache, io_cmd_cache_free);
 	io_alloc_cache_free(&ctx->msg_cache, kfree);
 	io_futex_cache_free(ctx);
 	io_rsrc_cache_free(ctx);
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 7fd173197b1e..e275180c2077 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -755,6 +755,7 @@ const struct io_cold_def io_cold_defs[] = {
 	},
 	[IORING_OP_URING_CMD] = {
 		.name			= "URING_CMD",
+		.cleanup		= io_uring_cmd_cleanup,
 	},
 	[IORING_OP_SEND_ZC] = {
 		.name			= "SEND_ZC",
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index de39b602aa82..315c603cfdd4 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -28,6 +28,13 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (issue_flags & IO_URING_F_UNLOCKED)
 		return;
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+
+	io_alloc_cache_vec_kasan(&cache->iou_vec);
+	if (cache->iou_vec.nr > IO_VEC_CACHE_SOFT_CAP)
+		io_vec_free(&cache->iou_vec);
+
 	if (io_alloc_cache_put(&req->ctx->uring_cache, cache)) {
 		ioucmd->sqe = NULL;
 		req->async_data = NULL;
@@ -35,6 +42,11 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
 	}
 }
 
+void io_uring_cmd_cleanup(struct io_kiocb *req)
+{
+	io_req_uring_cleanup(req, 0);
+}
+
 bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
 				   struct io_uring_task *tctx, bool cancel_all)
 {
@@ -339,3 +351,11 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 }
 EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
 #endif
+
+void io_cmd_cache_free(const void *entry)
+{
+	struct io_uring_cmd_data *cache = (struct io_uring_cmd_data *)entry;
+
+	io_vec_free(&cache->iou_vec);
+	kfree(cache);
+}
diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
index f6837ee0955b..d2b9c1522e22 100644
--- a/io_uring/uring_cmd.h
+++ b/io_uring/uring_cmd.h
@@ -1,7 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <linux/io_uring_types.h>
 
 int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
 int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_uring_cmd_cleanup(struct io_kiocb *req);
 
 bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
 				   struct io_uring_task *tctx, bool cancel_all);
+void io_cmd_cache_free(const void *entry);
-- 
2.43.0

Re: [RFC PATCH v3 1/3] io-uring/cmd: add iou_vec field for io_uring_cmd

[Pavel Begunkov]

On 3/15/25 17:23, Sidong Yang wrote:
> This patch adds iou_vec field for io_uring_cmd. Also it needs to be
> cleanup for cache. It could be used in uring cmd api that imports
> multiple fixed buffers.

Sidong, I think you accidentially erased my authorship over the
patch. The only difference I see is that you rebased it and dropped
prep patches by placing iou_vec into struct io_uring_cmd_data. And
the prep patch was mandatory, once something is exported there is
a good chance it gets [ab]used, and iou_vec is not ready for it.


> Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
> ---
>   include/linux/io_uring/cmd.h |  1 +
>   io_uring/io_uring.c          |  2 +-
>   io_uring/opdef.c             |  1 +
>   io_uring/uring_cmd.c         | 20 ++++++++++++++++++++
>   io_uring/uring_cmd.h         |  3 +++
>   5 files changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
> index 598cacda4aa3..74b9f0aec229 100644
> --- a/include/linux/io_uring/cmd.h
> +++ b/include/linux/io_uring/cmd.h
> @@ -22,6 +22,7 @@ struct io_uring_cmd {
>   struct io_uring_cmd_data {
>   	void			*op_data;
>   	struct io_uring_sqe	sqes[2];
> +	struct iou_vec		iou_vec;
>   };
>   
>   static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index 5ff30a7092ed..55334fa53abf 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -289,7 +289,7 @@ static void io_free_alloc_caches(struct io_ring_ctx *ctx)
>   	io_alloc_cache_free(&ctx->apoll_cache, kfree);
>   	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
>   	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
> -	io_alloc_cache_free(&ctx->uring_cache, kfree);
> +	io_alloc_cache_free(&ctx->uring_cache, io_cmd_cache_free);
>   	io_alloc_cache_free(&ctx->msg_cache, kfree);
>   	io_futex_cache_free(ctx);
>   	io_rsrc_cache_free(ctx);
> diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> index 7fd173197b1e..e275180c2077 100644
> --- a/io_uring/opdef.c
> +++ b/io_uring/opdef.c
> @@ -755,6 +755,7 @@ const struct io_cold_def io_cold_defs[] = {
>   	},
>   	[IORING_OP_URING_CMD] = {
>   		.name			= "URING_CMD",
> +		.cleanup		= io_uring_cmd_cleanup,
>   	},
>   	[IORING_OP_SEND_ZC] = {
>   		.name			= "SEND_ZC",
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index de39b602aa82..315c603cfdd4 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -28,6 +28,13 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
>   
>   	if (issue_flags & IO_URING_F_UNLOCKED)
>   		return;
> +
> +	req->flags &= ~REQ_F_NEED_CLEANUP;
> +
> +	io_alloc_cache_vec_kasan(&cache->iou_vec);
> +	if (cache->iou_vec.nr > IO_VEC_CACHE_SOFT_CAP)
> +		io_vec_free(&cache->iou_vec);
> +
>   	if (io_alloc_cache_put(&req->ctx->uring_cache, cache)) {
>   		ioucmd->sqe = NULL;
>   		req->async_data = NULL;
> @@ -35,6 +42,11 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
>   	}
>   }
>   
> +void io_uring_cmd_cleanup(struct io_kiocb *req)
> +{
> +	io_req_uring_cleanup(req, 0);
> +}
> +
>   bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
>   				   struct io_uring_task *tctx, bool cancel_all)
>   {
> @@ -339,3 +351,11 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>   }
>   EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
>   #endif
> +
> +void io_cmd_cache_free(const void *entry)
> +{
> +	struct io_uring_cmd_data *cache = (struct io_uring_cmd_data *)entry;
> +
> +	io_vec_free(&cache->iou_vec);
> +	kfree(cache);
> +}
> diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
> index f6837ee0955b..d2b9c1522e22 100644
> --- a/io_uring/uring_cmd.h
> +++ b/io_uring/uring_cmd.h
> @@ -1,7 +1,10 @@
>   // SPDX-License-Identifier: GPL-2.0
> +#include <linux/io_uring_types.h>
>   
>   int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
>   int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
> +void io_uring_cmd_cleanup(struct io_kiocb *req);
>   
>   bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
>   				   struct io_uring_task *tctx, bool cancel_all);
> +void io_cmd_cache_free(const void *entry);

-- 
Pavel Begunkov

Re: [RFC PATCH v3 1/3] io-uring/cmd: add iou_vec field for io_uring_cmd

[Sidong Yang]

On Sun, Mar 16, 2025 at 07:24:32AM +0000, Pavel Begunkov wrote:
> On 3/15/25 17:23, Sidong Yang wrote:
> > This patch adds iou_vec field for io_uring_cmd. Also it needs to be
> > cleanup for cache. It could be used in uring cmd api that imports
> > multiple fixed buffers.
> 
> Sidong, I think you accidentially erased my authorship over the
> patch. The only difference I see is that you rebased it and dropped
> prep patches by placing iou_vec into struct io_uring_cmd_data. And
> the prep patch was mandatory, once something is exported there is
> a good chance it gets [ab]used, and iou_vec is not ready for it.

Yes, First I thought it's not mandatory for this function. But it seems that
it's needed. I see that your patch hides all fields in io_uring_cmd_data but
op_data needed to be accessable for btrfs cmd. And I'll take a look for the
code referencing sqes in io_uring_cmd_data. Let me add the commit for next
version v4.

Thanks,
Sidong

> 
> 
> > Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
> > ---
> >   include/linux/io_uring/cmd.h |  1 +
> >   io_uring/io_uring.c          |  2 +-
> >   io_uring/opdef.c             |  1 +
> >   io_uring/uring_cmd.c         | 20 ++++++++++++++++++++
> >   io_uring/uring_cmd.h         |  3 +++
> >   5 files changed, 26 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
> > index 598cacda4aa3..74b9f0aec229 100644
> > --- a/include/linux/io_uring/cmd.h
> > +++ b/include/linux/io_uring/cmd.h
> > @@ -22,6 +22,7 @@ struct io_uring_cmd {
> >   struct io_uring_cmd_data {
> >   	void			*op_data;
> >   	struct io_uring_sqe	sqes[2];
> > +	struct iou_vec		iou_vec;
> >   };
> >   static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
> > diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> > index 5ff30a7092ed..55334fa53abf 100644
> > --- a/io_uring/io_uring.c
> > +++ b/io_uring/io_uring.c
> > @@ -289,7 +289,7 @@ static void io_free_alloc_caches(struct io_ring_ctx *ctx)
> >   	io_alloc_cache_free(&ctx->apoll_cache, kfree);
> >   	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
> >   	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
> > -	io_alloc_cache_free(&ctx->uring_cache, kfree);
> > +	io_alloc_cache_free(&ctx->uring_cache, io_cmd_cache_free);
> >   	io_alloc_cache_free(&ctx->msg_cache, kfree);
> >   	io_futex_cache_free(ctx);
> >   	io_rsrc_cache_free(ctx);
> > diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> > index 7fd173197b1e..e275180c2077 100644
> > --- a/io_uring/opdef.c
> > +++ b/io_uring/opdef.c
> > @@ -755,6 +755,7 @@ const struct io_cold_def io_cold_defs[] = {
> >   	},
> >   	[IORING_OP_URING_CMD] = {
> >   		.name			= "URING_CMD",
> > +		.cleanup		= io_uring_cmd_cleanup,
> >   	},
> >   	[IORING_OP_SEND_ZC] = {
> >   		.name			= "SEND_ZC",
> > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> > index de39b602aa82..315c603cfdd4 100644
> > --- a/io_uring/uring_cmd.c
> > +++ b/io_uring/uring_cmd.c
> > @@ -28,6 +28,13 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
> >   	if (issue_flags & IO_URING_F_UNLOCKED)
> >   		return;
> > +
> > +	req->flags &= ~REQ_F_NEED_CLEANUP;
> > +
> > +	io_alloc_cache_vec_kasan(&cache->iou_vec);
> > +	if (cache->iou_vec.nr > IO_VEC_CACHE_SOFT_CAP)
> > +		io_vec_free(&cache->iou_vec);
> > +
> >   	if (io_alloc_cache_put(&req->ctx->uring_cache, cache)) {
> >   		ioucmd->sqe = NULL;
> >   		req->async_data = NULL;
> > @@ -35,6 +42,11 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
> >   	}
> >   }
> > +void io_uring_cmd_cleanup(struct io_kiocb *req)
> > +{
> > +	io_req_uring_cleanup(req, 0);
> > +}
> > +
> >   bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
> >   				   struct io_uring_task *tctx, bool cancel_all)
> >   {
> > @@ -339,3 +351,11 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
> >   }
> >   EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
> >   #endif
> > +
> > +void io_cmd_cache_free(const void *entry)
> > +{
> > +	struct io_uring_cmd_data *cache = (struct io_uring_cmd_data *)entry;
> > +
> > +	io_vec_free(&cache->iou_vec);
> > +	kfree(cache);
> > +}
> > diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
> > index f6837ee0955b..d2b9c1522e22 100644
> > --- a/io_uring/uring_cmd.h
> > +++ b/io_uring/uring_cmd.h
> > @@ -1,7 +1,10 @@
> >   // SPDX-License-Identifier: GPL-2.0
> > +#include <linux/io_uring_types.h>
> >   int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
> >   int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
> > +void io_uring_cmd_cleanup(struct io_kiocb *req);
> >   bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
> >   				   struct io_uring_task *tctx, bool cancel_all);
> > +void io_cmd_cache_free(const void *entry);
> 
> -- 
> Pavel Begunkov
> 

Re: [RFC PATCH v3 1/3] io-uring/cmd: add iou_vec field for io_uring_cmd

[Sidong Yang]

On Sun, Mar 16, 2025 at 05:02:19PM +0900, Sidong Yang wrote:
> On Sun, Mar 16, 2025 at 07:24:32AM +0000, Pavel Begunkov wrote:
> > On 3/15/25 17:23, Sidong Yang wrote:
> > > This patch adds iou_vec field for io_uring_cmd. Also it needs to be
> > > cleanup for cache. It could be used in uring cmd api that imports
> > > multiple fixed buffers.
> > 
> > Sidong, I think you accidentially erased my authorship over the
> > patch. The only difference I see is that you rebased it and dropped
> > prep patches by placing iou_vec into struct io_uring_cmd_data. And
> > the prep patch was mandatory, once something is exported there is
> > a good chance it gets [ab]used, and iou_vec is not ready for it.
> 
> Yes, First I thought it's not mandatory for this function. But it seems that
> it's needed. I see that your patch hides all fields in io_uring_cmd_data but
> op_data needed to be accessable for btrfs cmd. And I'll take a look for the
> code referencing sqes in io_uring_cmd_data. Let me add the commit for next
> version v4.

I've just realized that your commit don't need to be modified. It's okay to
cast async_data to io_uring_cmd_data. 

Thanks,
Sidong
> 
> Thanks,
> Sidong
> 
> > 
> > 
> > > Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
> > > ---
> > >   include/linux/io_uring/cmd.h |  1 +
> > >   io_uring/io_uring.c          |  2 +-
> > >   io_uring/opdef.c             |  1 +
> > >   io_uring/uring_cmd.c         | 20 ++++++++++++++++++++
> > >   io_uring/uring_cmd.h         |  3 +++
> > >   5 files changed, 26 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
> > > index 598cacda4aa3..74b9f0aec229 100644
> > > --- a/include/linux/io_uring/cmd.h
> > > +++ b/include/linux/io_uring/cmd.h
> > > @@ -22,6 +22,7 @@ struct io_uring_cmd {
> > >   struct io_uring_cmd_data {
> > >   	void			*op_data;
> > >   	struct io_uring_sqe	sqes[2];
> > > +	struct iou_vec		iou_vec;
> > >   };
> > >   static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
> > > diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> > > index 5ff30a7092ed..55334fa53abf 100644
> > > --- a/io_uring/io_uring.c
> > > +++ b/io_uring/io_uring.c
> > > @@ -289,7 +289,7 @@ static void io_free_alloc_caches(struct io_ring_ctx *ctx)
> > >   	io_alloc_cache_free(&ctx->apoll_cache, kfree);
> > >   	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
> > >   	io_alloc_cache_free(&ctx->rw_cache, io_rw_cache_free);
> > > -	io_alloc_cache_free(&ctx->uring_cache, kfree);
> > > +	io_alloc_cache_free(&ctx->uring_cache, io_cmd_cache_free);
> > >   	io_alloc_cache_free(&ctx->msg_cache, kfree);
> > >   	io_futex_cache_free(ctx);
> > >   	io_rsrc_cache_free(ctx);
> > > diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> > > index 7fd173197b1e..e275180c2077 100644
> > > --- a/io_uring/opdef.c
> > > +++ b/io_uring/opdef.c
> > > @@ -755,6 +755,7 @@ const struct io_cold_def io_cold_defs[] = {
> > >   	},
> > >   	[IORING_OP_URING_CMD] = {
> > >   		.name			= "URING_CMD",
> > > +		.cleanup		= io_uring_cmd_cleanup,
> > >   	},
> > >   	[IORING_OP_SEND_ZC] = {
> > >   		.name			= "SEND_ZC",
> > > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> > > index de39b602aa82..315c603cfdd4 100644
> > > --- a/io_uring/uring_cmd.c
> > > +++ b/io_uring/uring_cmd.c
> > > @@ -28,6 +28,13 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
> > >   	if (issue_flags & IO_URING_F_UNLOCKED)
> > >   		return;
> > > +
> > > +	req->flags &= ~REQ_F_NEED_CLEANUP;
> > > +
> > > +	io_alloc_cache_vec_kasan(&cache->iou_vec);
> > > +	if (cache->iou_vec.nr > IO_VEC_CACHE_SOFT_CAP)
> > > +		io_vec_free(&cache->iou_vec);
> > > +
> > >   	if (io_alloc_cache_put(&req->ctx->uring_cache, cache)) {
> > >   		ioucmd->sqe = NULL;
> > >   		req->async_data = NULL;
> > > @@ -35,6 +42,11 @@ static void io_req_uring_cleanup(struct io_kiocb *req, unsigned int issue_flags)
> > >   	}
> > >   }
> > > +void io_uring_cmd_cleanup(struct io_kiocb *req)
> > > +{
> > > +	io_req_uring_cleanup(req, 0);
> > > +}
> > > +
> > >   bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
> > >   				   struct io_uring_task *tctx, bool cancel_all)
> > >   {
> > > @@ -339,3 +351,11 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
> > >   }
> > >   EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
> > >   #endif
> > > +
> > > +void io_cmd_cache_free(const void *entry)
> > > +{
> > > +	struct io_uring_cmd_data *cache = (struct io_uring_cmd_data *)entry;
> > > +
> > > +	io_vec_free(&cache->iou_vec);
> > > +	kfree(cache);
> > > +}
> > > diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
> > > index f6837ee0955b..d2b9c1522e22 100644
> > > --- a/io_uring/uring_cmd.h
> > > +++ b/io_uring/uring_cmd.h
> > > @@ -1,7 +1,10 @@
> > >   // SPDX-License-Identifier: GPL-2.0
> > > +#include <linux/io_uring_types.h>
> > >   int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
> > >   int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
> > > +void io_uring_cmd_cleanup(struct io_kiocb *req);
> > >   bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
> > >   				   struct io_uring_task *tctx, bool cancel_all);
> > > +void io_cmd_cache_free(const void *entry);
> > 
> > -- 
> > Pavel Begunkov
> > 

[RFC PATCH v3 2/3] io-uring/cmd: introduce io_uring_cmd_import_fixed_vec

[Sidong Yang]

io_uring_cmd_import_fixed_vec() could be used for using multiple
fixed buffer in uring_cmd callback.

Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
---
 include/linux/io_uring/cmd.h | 14 ++++++++++++++
 io_uring/uring_cmd.c         | 19 +++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 74b9f0aec229..2c7ae8474a56 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -45,6 +45,12 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 			      struct io_uring_cmd *ioucmd,
 			      unsigned int issue_flags);
 
+int io_uring_cmd_import_fixed_vec(struct io_uring_cmd *ioucmd,
+				  const struct iovec __user *uvec,
+				  unsigned long uvec_segs, int ddir,
+				  unsigned int issue_flags,
+				  struct iov_iter *iter);
+
 /*
  * Completes the request, i.e. posts an io_uring CQE and deallocates @ioucmd
  * and the corresponding io_uring request.
@@ -77,6 +83,14 @@ io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 {
 	return -EOPNOTSUPP;
 }
+int io_uring_cmd_import_fixed_vec(struct io_uring_cmd *ioucmd,
+				  const struct iovec __user *uvec,
+				  unsigned long uvec_segs, int ddir,
+				  unsigned int issue_flags,
+				  struct iov_iter *iter)
+{
+	return -EOPNOTSUPP;
+}
 static inline void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret,
 		u64 ret2, unsigned issue_flags)
 {
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 315c603cfdd4..e2bf9edca9df 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -267,6 +267,25 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 }
 EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
 
+int io_uring_cmd_import_fixed_vec(struct io_uring_cmd *ioucmd,
+				  const struct iovec __user *uvec,
+				  unsigned long uvec_segs, int ddir,
+				  unsigned int issue_flags,
+				  struct iov_iter *iter)
+{
+	struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
+	struct io_uring_cmd_data *cache = req->async_data;
+	int ret;
+
+	ret = io_prep_reg_iovec(req, &cache->iou_vec, uvec, uvec_segs);
+	if (ret)
+		return ret;
+
+	return io_import_reg_vec(ddir, iter, req, &cache->iou_vec,
+				 cache->iou_vec.nr, issue_flags);
+}
+EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed_vec);
+
 void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd)
 {
 	struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
-- 
2.43.0

[RFC PATCH v3 3/3] btrfs: ioctl: introduce btrfs_uring_import_iovec()

[Sidong Yang]

This patch introduces btrfs_uring_import_iovec(). In encoded read/write
with uring cmd, it uses import_iovec without supporting fixed buffer.
btrfs_using_import_iovec() could use fixed buffer if cmd flags has
IORING_URING_CMD_FIXED.

Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
---
 fs/btrfs/ioctl.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6c18bad53cd3..a7b52fd99059 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4802,6 +4802,28 @@ struct btrfs_uring_encoded_data {
 	struct iov_iter iter;
 };
 
+static int btrfs_uring_import_iovec(struct io_uring_cmd *cmd,
+				    unsigned int issue_flags, int rw)
+{
+	struct btrfs_uring_encoded_data *data =
+		io_uring_cmd_get_async_data(cmd)->op_data;
+	int ret;
+
+	if (cmd && (cmd->flags & IORING_URING_CMD_FIXED)) {
+		data->iov = NULL;
+		ret = io_uring_cmd_import_fixed_vec(cmd, data->args.iov,
+						    data->args.iovcnt,
+						    ITER_DEST, issue_flags,
+						    &data->iter);
+	} else {
+		data->iov = data->iovstack;
+		ret = import_iovec(rw, data->args.iov, data->args.iovcnt,
+				   ARRAY_SIZE(data->iovstack), &data->iov,
+				   &data->iter);
+	}
+	return ret;
+}
+
 static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue_flags)
 {
 	size_t copy_end_kernel = offsetofend(struct btrfs_ioctl_encoded_io_args, flags);
@@ -4874,10 +4896,7 @@ static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue
 			goto out_acct;
 		}
 
-		data->iov = data->iovstack;
-		ret = import_iovec(ITER_DEST, data->args.iov, data->args.iovcnt,
-				   ARRAY_SIZE(data->iovstack), &data->iov,
-				   &data->iter);
+		ret = btrfs_uring_import_iovec(cmd, issue_flags, ITER_DEST);
 		if (ret < 0)
 			goto out_acct;
 
@@ -5022,10 +5041,7 @@ static int btrfs_uring_encoded_write(struct io_uring_cmd *cmd, unsigned int issu
 		if (data->args.len > data->args.unencoded_len - data->args.unencoded_offset)
 			goto out_acct;
 
-		data->iov = data->iovstack;
-		ret = import_iovec(ITER_SOURCE, data->args.iov, data->args.iovcnt,
-				   ARRAY_SIZE(data->iovstack), &data->iov,
-				   &data->iter);
+		ret = btrfs_uring_import_iovec(cmd, issue_flags, ITER_SOURCE);
 		if (ret < 0)
 			goto out_acct;
 
-- 
2.43.0

Re: [RFC PATCH v3 0/3] introduce io_uring_cmd_import_fixed_vec

[Pavel Begunkov]

On 3/15/25 17:23, Sidong Yang wrote:
> This patche series introduce io_uring_cmd_import_vec. With this function,
> Multiple fixed buffer could be used in uring cmd. It's vectored version
> for io_uring_cmd_import_fixed(). Also this patch series includes a usage
> for new api for encoded read/write in btrfs by using uring cmd.
> 
> There was approximately 10 percent of performance improvements through benchmark.
> The benchmark code is in
> https://github.com/SidongYang/btrfs-encoded-io-test/blob/main/main.c
> 
> ./main -l
> Elapsed time: 0.598997 seconds
> ./main -l -f
> Elapsed time: 0.540332 seconds

It's probably precise, but it's usually hard to judge about
performance from such short runs. Mark, do we have some benchmark
for the io_uring cmd?

-- 
Pavel Begunkov