[PATCH 0/3] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL

[PATCH 0/3] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL

[Caleb Sander Mateos]

Currently, creating an io_uring with IORING_SETUP_IOPOLL requires all
requests issued to it to support iopoll. This prevents, for example,
using ublk zero-copy together with IORING_SETUP_IOPOLL, as ublk
zero-copy buffer registrations are performed using a uring_cmd. There's
no technical reason why these non-iopoll uring_cmds can't be supported.
They will either complete synchronously or via an external mechanism
that calls io_uring_cmd_done(), so they don't need to be polled.

Allow uring_cmd requests to be issued to IORING_SETUP_IOPOLL io_urings
even if their files don't implement ->uring_cmd_iopoll().

The first commit fixes a few bugs where IORING_OP_URING_CMD128 isn't
treated as IORING_OP_URING_CMD with iopoll and provided buffers.

The last commit removes an unnecessary IO_URING_F_IOPOLL check in
nvme_dev_uring_cmd() as NVMe admin passthru commands can be issued to
IORING_SETUP_IOPOLL io_urings now.

Caleb Sander Mateos (3):
  io_uring: add IORING_OP_URING_CMD128 to opcode checks
  io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL
  nvme: remove nvme_dev_uring_cmd() IO_URING_F_IOPOLL check

 drivers/nvme/host/ioctl.c |  4 ----
 io_uring/io_uring.c       |  4 +++-
 io_uring/io_uring.h       |  6 ++++++
 io_uring/kbuf.c           |  2 +-
 io_uring/rw.c             |  4 ++--
 io_uring/uring_cmd.c      | 11 +++++------
 6 files changed, 17 insertions(+), 14 deletions(-)

-- 
2.45.2

[PATCH 1/3] io_uring: add IORING_OP_URING_CMD128 to opcode checks

[Caleb Sander Mateos]

io_should_commit(), io_uring_classic_poll(), and io_do_iopoll() compare
struct io_kiocb's opcode against IORING_OP_URING_CMD to implement
special treatment for uring_cmds. The recently added opcode
IORING_OP_URING_CMD128 is meant to be equivalent to IORING_OP_URING_CMD,
so treat it the same way in these functions.

Fixes: 1cba30bf9fdd ("io_uring: add support for IORING_SETUP_SQE_MIXED")
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 io_uring/io_uring.h | 6 ++++++
 io_uring/kbuf.c     | 2 +-
 io_uring/rw.c       | 4 ++--
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index 503663d6fd6d..0fa844faf287 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -528,10 +528,16 @@ static inline bool io_file_can_poll(struct io_kiocb *req)
 		return true;
 	}
 	return false;
 }
 
+static inline bool io_is_uring_cmd(const struct io_kiocb *req)
+{
+	return req->opcode == IORING_OP_URING_CMD ||
+	       req->opcode == IORING_OP_URING_CMD128;
+}
+
 static inline ktime_t io_get_time(struct io_ring_ctx *ctx)
 {
 	if (ctx->clockid == CLOCK_MONOTONIC)
 		return ktime_get();
 
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 67d4fe576473..dae5b4ab3819 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -169,11 +169,11 @@ static bool io_should_commit(struct io_kiocb *req, unsigned int issue_flags)
 	*/
 	if (issue_flags & IO_URING_F_UNLOCKED)
 		return true;
 
 	/* uring_cmd commits kbuf upfront, no need to auto-commit */
-	if (!io_file_can_poll(req) && req->opcode != IORING_OP_URING_CMD)
+	if (!io_file_can_poll(req) && !io_is_uring_cmd(req))
 		return true;
 	return false;
 }
 
 static struct io_br_sel io_ring_buffer_select(struct io_kiocb *req, size_t *len,
diff --git a/io_uring/rw.c b/io_uring/rw.c
index b3971171c342..1a5f262734e8 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -1252,11 +1252,11 @@ void io_rw_fail(struct io_kiocb *req)
 static int io_uring_classic_poll(struct io_kiocb *req, struct io_comp_batch *iob,
 				unsigned int poll_flags)
 {
 	struct file *file = req->file;
 
-	if (req->opcode == IORING_OP_URING_CMD) {
+	if (io_is_uring_cmd(req)) {
 		struct io_uring_cmd *ioucmd;
 
 		ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
 		return file->f_op->uring_cmd_iopoll(ioucmd, iob, poll_flags);
 	} else {
@@ -1378,11 +1378,11 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
 			continue;
 		list_del(&req->iopoll_node);
 		wq_list_add_tail(&req->comp_list, &ctx->submit_state.compl_reqs);
 		nr_events++;
 		req->cqe.flags = io_put_kbuf(req, req->cqe.res, NULL);
-		if (req->opcode != IORING_OP_URING_CMD)
+		if (!io_is_uring_cmd(req))
 			io_req_rw_cleanup(req, 0);
 	}
 	if (nr_events)
 		__io_submit_flush_completions(ctx);
 	return nr_events;
-- 
2.45.2

[PATCH 2/3] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL

[Caleb Sander Mateos]

Currently, creating an io_uring with IORING_SETUP_IOPOLL requires all
requests issued to it to support iopoll. This prevents, for example,
using ublk zero-copy together with IORING_SETUP_IOPOLL, as ublk
zero-copy buffer registrations are performed using a uring_cmd. There's
no technical reason why these non-iopoll uring_cmds can't be supported.
They will either complete synchronously or via an external mechanism
that calls io_uring_cmd_done(), so they don't need to be polled.

Allow uring_cmd requests to be issued to IORING_SETUP_IOPOLL io_urings
even if their files don't implement ->uring_cmd_iopoll(). For these
uring_cmd requests, skip initializing struct io_kiocb's iopoll fields,
don't insert the request into iopoll_list, and take the
io_req_complete_defer() or io_req_task_work_add() path in
__io_uring_cmd_done() instead of setting the iopoll_completed flag. Also
allow io_uring_cmd_mark_cancelable() to be called on these uring_cmds.
Assert that io_uring_cmd_mark_cancelable() is only called on
non-IORING_SETUP_IOPOLL io_urings or uring_cmds to files that don't
implement ->uring_cmd_iopoll().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 io_uring/io_uring.c  |  4 +++-
 io_uring/uring_cmd.c | 11 +++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index c45af82dda3d..4e68a5168894 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1417,11 +1417,13 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (ret == IOU_ISSUE_SKIP_COMPLETE) {
 		ret = 0;
 
 		/* If the op doesn't have a file, we're not polling for it */
-		if ((req->ctx->flags & IORING_SETUP_IOPOLL) && def->iopoll_queue)
+		if ((req->ctx->flags & IORING_SETUP_IOPOLL) &&
+		    def->iopoll_queue && (!io_is_uring_cmd(req) ||
+					  req->file->f_op->uring_cmd_iopoll))
 			io_iopoll_req_issued(req, issue_flags);
 	}
 	return ret;
 }
 
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index ee7b49f47cb5..8df52e8f1c1b 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -108,12 +108,12 @@ void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
 	 * Doing cancelations on IOPOLL requests are not supported. Both
 	 * because they can't get canceled in the block stack, but also
 	 * because iopoll completion data overlaps with the hash_node used
 	 * for tracking.
 	 */
-	if (ctx->flags & IORING_SETUP_IOPOLL)
-		return;
+	WARN_ON_ONCE(ctx->flags & IORING_SETUP_IOPOLL &&
+		     req->file->f_op->uring_cmd_iopoll);
 
 	if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) {
 		cmd->flags |= IORING_URING_CMD_CANCELABLE;
 		io_ring_submit_lock(ctx, issue_flags);
 		hlist_add_head(&req->hash_node, &ctx->cancelable_uring_cmd);
@@ -165,11 +165,12 @@ void __io_uring_cmd_done(struct io_uring_cmd *ioucmd, s32 ret, u64 res2,
 		if (req->ctx->flags & IORING_SETUP_CQE_MIXED)
 			req->cqe.flags |= IORING_CQE_F_32;
 		io_req_set_cqe32_extra(req, res2, 0);
 	}
 	io_req_uring_cleanup(req, issue_flags);
-	if (req->ctx->flags & IORING_SETUP_IOPOLL) {
+	if (req->ctx->flags & IORING_SETUP_IOPOLL &&
+	    req->file->f_op->uring_cmd_iopoll) {
 		/* order with io_iopoll_req_issued() checking ->iopoll_complete */
 		smp_store_release(&req->iopoll_completed, 1);
 	} else if (issue_flags & IO_URING_F_COMPLETE_DEFER) {
 		if (WARN_ON_ONCE(issue_flags & IO_URING_F_UNLOCKED))
 			return;
@@ -255,13 +256,11 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
 		issue_flags |= IO_URING_F_SQE128;
 	if (ctx->flags & (IORING_SETUP_CQE32 | IORING_SETUP_CQE_MIXED))
 		issue_flags |= IO_URING_F_CQE32;
 	if (io_is_compat(ctx))
 		issue_flags |= IO_URING_F_COMPAT;
-	if (ctx->flags & IORING_SETUP_IOPOLL) {
-		if (!file->f_op->uring_cmd_iopoll)
-			return -EOPNOTSUPP;
+	if (ctx->flags & IORING_SETUP_IOPOLL && file->f_op->uring_cmd_iopoll) {
 		issue_flags |= IO_URING_F_IOPOLL;
 		req->iopoll_completed = 0;
 		if (ctx->flags & IORING_SETUP_HYBRID_IOPOLL) {
 			/* make sure every req only blocks once */
 			req->flags &= ~REQ_F_IOPOLL_STATE;
-- 
2.45.2

[PATCH 3/3] nvme: remove nvme_dev_uring_cmd() IO_URING_F_IOPOLL check

[Caleb Sander Mateos]

nvme_dev_uring_cmd() is part of struct file_operations nvme_dev_fops,
which doesn't implement ->uring_cmd_iopoll(). So it won't be called with
issue_flags that include IO_URING_F_IOPOLL. Drop the unnecessary
IO_URING_F_IOPOLL check in nvme_dev_uring_cmd().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 drivers/nvme/host/ioctl.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index fb62633ccbb0..fa489c1979db 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -783,14 +783,10 @@ int nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,
 int nvme_dev_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
 {
 	struct nvme_ctrl *ctrl = ioucmd->file->private_data;
 	int ret;
 
-	/* IOPOLL not supported yet */
-	if (issue_flags & IO_URING_F_IOPOLL)
-		return -EOPNOTSUPP;
-
 	ret = nvme_uring_cmd_checks(issue_flags);
 	if (ret)
 		return ret;
 
 	switch (ioucmd->cmd_op) {
-- 
2.45.2