[PATCH v2 3/9] io_uring: use inflight_entry list for iopoll'ing

[Pavel Begunkov <asml.silence@xxxxxxxxx>]

req->inflight_entry is used to track requests that grabbed files_struct.
Let's share it with iopoll list, because the only iopoll'ed ops are
reads and writes, which don't need a file table.

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
 fs/io_uring.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 03bb8a69d09c..1ad6d47a6223 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -650,6 +650,10 @@ struct io_kiocb {
 
 	struct list_head	link_list;
 
+	/*
+	 * 1. used with ctx->iopoll_list with reads/writes
+	 * 2. to track reqs with ->files (see io_op_def::file_table)
+	 */
 	struct list_head	inflight_entry;
 
 	struct percpu_ref	*fixed_file_refs;
@@ -1942,8 +1946,8 @@ static void io_iopoll_queue(struct list_head *again)
 	struct io_kiocb *req;
 
 	do {
-		req = list_first_entry(again, struct io_kiocb, list);
-		list_del(&req->list);
+		req = list_first_entry(again, struct io_kiocb, inflight_entry);
+		list_del(&req->inflight_entry);
 		if (!io_rw_reissue(req, -EAGAIN))
 			io_complete_rw_common(&req->rw.kiocb, -EAGAIN, NULL);
 	} while (!list_empty(again));
@@ -1966,13 +1970,13 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 	while (!list_empty(done)) {
 		int cflags = 0;
 
-		req = list_first_entry(done, struct io_kiocb, list);
+		req = list_first_entry(done, struct io_kiocb, inflight_entry);
 		if (READ_ONCE(req->result) == -EAGAIN) {
 			req->iopoll_completed = 0;
-			list_move_tail(&req->list, &again);
+			list_move_tail(&req->inflight_entry, &again);
 			continue;
 		}
-		list_del(&req->list);
+		list_del(&req->inflight_entry);
 
 		if (req->flags & REQ_F_BUFFER_SELECTED)
 			cflags = io_put_kbuf(req);
@@ -2008,7 +2012,7 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 	spin = !ctx->poll_multi_file && *nr_events < min;
 
 	ret = 0;
-	list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, list) {
+	list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, inflight_entry) {
 		struct kiocb *kiocb = &req->rw.kiocb;
 
 		/*
@@ -2017,7 +2021,7 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 		 * and complete those lists first, if we have entries there.
 		 */
 		if (READ_ONCE(req->iopoll_completed)) {
-			list_move_tail(&req->list, &done);
+			list_move_tail(&req->inflight_entry, &done);
 			continue;
 		}
 		if (!list_empty(&done))
@@ -2029,7 +2033,7 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 
 		/* iopoll may have completed current req */
 		if (READ_ONCE(req->iopoll_completed))
-			list_move_tail(&req->list, &done);
+			list_move_tail(&req->inflight_entry, &done);
 
 		if (ret && spin)
 			spin = false;
@@ -2296,7 +2300,7 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
 		struct io_kiocb *list_req;
 
 		list_req = list_first_entry(&ctx->iopoll_list, struct io_kiocb,
-						list);
+						inflight_entry);
 		if (list_req->file != req->file)
 			ctx->poll_multi_file = true;
 	}
@@ -2306,9 +2310,9 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
 	 * it to the front so we find it first.
 	 */
 	if (READ_ONCE(req->iopoll_completed))
-		list_add(&req->list, &ctx->iopoll_list);
+		list_add(&req->inflight_entry, &ctx->iopoll_list);
 	else
-		list_add_tail(&req->list, &ctx->iopoll_list);
+		list_add_tail(&req->inflight_entry, &ctx->iopoll_list);
 
 	if ((ctx->flags & IORING_SETUP_SQPOLL) &&
 	    wq_has_sleeper(&ctx->sqo_wait))
-- 
2.24.0