[PATCH v2 1/4] io_uring: add REQ_F_IOPOLL

[Caleb Sander Mateos <csander@purestorage.com>]

A subsequent commit will allow uring_cmds to commands that don't
implement ->uring_cmd_iopoll() to be issued to IORING_SETUP_IOPOLL
io_urings. This means the ctx's IORING_SETUP_IOPOLL flag isn't
sufficient to determine whether a given request needs to be iopolled.
Introduce a request flag REQ_F_IOPOLL set in ->issue() if a request
needs to be iopolled to completion. Set the flag in io_rw_init_file()
and io_uring_cmd() for requests issued to IORING_SETUP_IOPOLL ctxs. Use
the request flag instead of IORING_SETUP_IOPOLL in places dealing with a
specific request.

A future possibility would be to add an option to enable/disable iopoll
in the io_uring SQE instead of determining it from IORING_SETUP_IOPOLL.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 include/linux/io_uring_types.h |  3 +++
 io_uring/io_uring.c            |  9 ++++-----
 io_uring/rw.c                  | 11 ++++++-----
 io_uring/uring_cmd.c           |  5 +++--
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 3e4a82a6f817..4563e1fafdf0 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -541,10 +541,11 @@ enum {
 	REQ_F_BUFFERS_COMMIT_BIT,
 	REQ_F_BUF_NODE_BIT,
 	REQ_F_HAS_METADATA_BIT,
 	REQ_F_IMPORT_BUFFER_BIT,
 	REQ_F_SQE_COPIED_BIT,
+	REW_F_IOPOLL_BIT,
 
 	/* not a real bit, just to check we're not overflowing the space */
 	__REQ_F_LAST_BIT,
 };
 
@@ -632,10 +633,12 @@ enum {
 	 * For SEND_ZC, whether to import buffers (i.e. the first issue).
 	 */
 	REQ_F_IMPORT_BUFFER	= IO_REQ_FLAG(REQ_F_IMPORT_BUFFER_BIT),
 	/* ->sqe_copy() has been called, if necessary */
 	REQ_F_SQE_COPIED	= IO_REQ_FLAG(REQ_F_SQE_COPIED_BIT),
+	/* request must be iopolled to completion (set in ->issue()) */
+	REQ_F_IOPOLL		= IO_REQ_FLAG(REW_F_IOPOLL_BIT),
 };
 
 struct io_tw_req {
 	struct io_kiocb *req;
 };
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ccab8562d273..43059f6e10e0 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -354,11 +354,10 @@ static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
 }
 
 static void io_prep_async_work(struct io_kiocb *req)
 {
 	const struct io_issue_def *def = &io_issue_defs[req->opcode];
-	struct io_ring_ctx *ctx = req->ctx;
 
 	if (!(req->flags & REQ_F_CREDS)) {
 		req->flags |= REQ_F_CREDS;
 		req->creds = get_current_cred();
 	}
@@ -376,11 +375,11 @@ static void io_prep_async_work(struct io_kiocb *req)
 
 		/* don't serialize this request if the fs doesn't need it */
 		if (should_hash && (req->file->f_flags & O_DIRECT) &&
 		    (req->file->f_op->fop_flags & FOP_DIO_PARALLEL_WRITE))
 			should_hash = false;
-		if (should_hash || (ctx->flags & IORING_SETUP_IOPOLL))
+		if (should_hash || (req->flags & REQ_F_IOPOLL))
 			io_wq_hash_work(&req->work, file_inode(req->file));
 	} else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
 		if (def->unbound_nonreg_file)
 			atomic_or(IO_WQ_WORK_UNBOUND, &req->work.flags);
 	}
@@ -1417,11 +1416,11 @@ 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->flags & REQ_F_IOPOLL) && def->iopoll_queue)
 			io_iopoll_req_issued(req, issue_flags);
 	}
 	return ret;
 }
 
@@ -1433,11 +1432,11 @@ int io_poll_issue(struct io_kiocb *req, io_tw_token_t tw)
 	int ret;
 
 	io_tw_lock(req->ctx, tw);
 
 	WARN_ON_ONCE(!req->file);
-	if (WARN_ON_ONCE(req->ctx->flags & IORING_SETUP_IOPOLL))
+	if (WARN_ON_ONCE(req->flags & REQ_F_IOPOLL))
 		return -EFAULT;
 
 	ret = __io_issue_sqe(req, issue_flags, &io_issue_defs[req->opcode]);
 
 	WARN_ON_ONCE(ret == IOU_ISSUE_SKIP_COMPLETE);
@@ -1531,11 +1530,11 @@ void io_wq_submit_work(struct io_wq_work *work)
 		 * We can get EAGAIN for iopolled IO even though we're
 		 * forcing a sync submission from here, since we can't
 		 * wait for request slots on the block side.
 		 */
 		if (!needs_poll) {
-			if (!(req->ctx->flags & IORING_SETUP_IOPOLL))
+			if (!(req->flags & REQ_F_IOPOLL))
 				break;
 			if (io_wq_worker_stopped())
 				break;
 			cond_resched();
 			continue;
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 1a5f262734e8..3bdb9914e673 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -502,11 +502,11 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
 	struct io_ring_ctx *ctx = req->ctx;
 
 	if (!S_ISBLK(mode) && !S_ISREG(mode))
 		return false;
 	if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
-	    !(ctx->flags & IORING_SETUP_IOPOLL)))
+	    !(req->flags & REQ_F_IOPOLL)))
 		return false;
 	/*
 	 * If ref is dying, we might be running poll reap from the exit work.
 	 * Don't attempt to reissue from that path, just let it fail with
 	 * -EAGAIN.
@@ -638,11 +638,11 @@ static inline void io_rw_done(struct io_kiocb *req, ssize_t ret)
 			ret = -EINTR;
 			break;
 		}
 	}
 
-	if (req->ctx->flags & IORING_SETUP_IOPOLL)
+	if (req->flags & REQ_F_IOPOLL)
 		io_complete_rw_iopoll(&rw->kiocb, ret);
 	else
 		io_complete_rw(&rw->kiocb, ret);
 }
 
@@ -652,11 +652,11 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret,
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	unsigned final_ret = io_fixup_rw_res(req, ret);
 
 	if (ret >= 0 && req->flags & REQ_F_CUR_POS)
 		req->file->f_pos = rw->kiocb.ki_pos;
-	if (ret >= 0 && !(req->ctx->flags & IORING_SETUP_IOPOLL)) {
+	if (ret >= 0 && !(req->flags & REQ_F_IOPOLL)) {
 		u32 cflags = 0;
 
 		__io_complete_rw_common(req, ret);
 		/*
 		 * Safe to call io_end from here as we're inline
@@ -874,10 +874,11 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode, int rw_type)
 		req->flags |= REQ_F_NOWAIT;
 
 	if (ctx->flags & IORING_SETUP_IOPOLL) {
 		if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll)
 			return -EOPNOTSUPP;
+		req->flags |= REQ_F_IOPOLL;
 		kiocb->private = NULL;
 		kiocb->ki_flags |= IOCB_HIPRI;
 		req->iopoll_completed = 0;
 		if (ctx->flags & IORING_SETUP_HYBRID_IOPOLL) {
 			/* make sure every req only blocks once*/
@@ -961,11 +962,11 @@ static int __io_read(struct io_kiocb *req, struct io_br_sel *sel,
 	if (ret == -EAGAIN) {
 		/* If we can poll, just do that. */
 		if (io_file_can_poll(req))
 			return -EAGAIN;
 		/* IOPOLL retry should happen for io-wq threads */
-		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
+		if (!force_nonblock && !(req->flags & REQ_F_IOPOLL))
 			goto done;
 		/* no retry on NONBLOCK nor RWF_NOWAIT */
 		if (req->flags & REQ_F_NOWAIT)
 			goto done;
 		ret = 0;
@@ -1186,11 +1187,11 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
 	/* no retry on NONBLOCK nor RWF_NOWAIT */
 	if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
 		goto done;
 	if (!force_nonblock || ret2 != -EAGAIN) {
 		/* IOPOLL retry should happen for io-wq threads */
-		if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
+		if (ret2 == -EAGAIN && (req->flags & REQ_F_IOPOLL))
 			goto ret_eagain;
 
 		if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
 			trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
 						req->cqe.res, ret2);
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index ee7b49f47cb5..b651c63f6e20 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -108,11 +108,11 @@ 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)
+	if (req->flags & REQ_F_IOPOLL)
 		return;
 
 	if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) {
 		cmd->flags |= IORING_URING_CMD_CANCELABLE;
 		io_ring_submit_lock(ctx, issue_flags);
@@ -165,11 +165,11 @@ 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->flags & REQ_F_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;
@@ -258,10 +258,11 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
 	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;
+		req->flags |= REQ_F_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