FAILED: patch "[PATCH] io_uring/rw: fix cflags posting for single issue multishot" failed to apply to 6.11-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.11-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.11.y
git checkout FETCH_HEAD
git cherry-pick -x c9d952b9103b600ddafc5d1c0e2f2dbd30f0b805
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024101436-avalanche-approach-5c90@gregkh' --subject-prefix 'PATCH 6.11.y' HEAD^..

Possible dependencies:

c9d952b9103b ("io_uring/rw: fix cflags posting for single issue multishot read")
6733e678ba12 ("io_uring/kbuf: pass in 'len' argument for buffer commit")
ecd5c9b29643 ("io_uring/kbuf: add io_kbuf_commit() helper")
03e02e8f95fe ("io_uring/kbuf: use 'bl' directly rather than req->buf_list")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c9d952b9103b600ddafc5d1c0e2f2dbd30f0b805 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Sat, 5 Oct 2024 19:06:50 -0600
Subject: [PATCH] io_uring/rw: fix cflags posting for single issue multishot
 read

If multishot gets disabled, and hence the request will get terminated
rather than persist for more iterations, then posting the CQE with the
right cflags is still important. Most notably, the buffer reference
needs to be included.

Refactor the return of __io_read() a bit, so that the provided buffer
is always put correctly, and hence returned to the application.

Reported-by: Sharon Rosner <Sharon Rosner>
Link: https://github.com/axboe/liburing/issues/1257
Cc: stable@vger.kernel.org
Fixes: 2a975d426c82 ("io_uring/rw: don't allow multishot reads without NOWAIT support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/rw.c b/io_uring/rw.c
index f023ff49c688..93ad92605884 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -972,17 +972,21 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 		if (issue_flags & IO_URING_F_MULTISHOT)
 			return IOU_ISSUE_SKIP_COMPLETE;
 		return -EAGAIN;
-	}
-
-	/*
-	 * Any successful return value will keep the multishot read armed.
-	 */
-	if (ret > 0 && req->flags & REQ_F_APOLL_MULTISHOT) {
+	} else if (ret <= 0) {
+		io_kbuf_recycle(req, issue_flags);
+		if (ret < 0)
+			req_set_fail(req);
+	} else {
 		/*
-		 * Put our buffer and post a CQE. If we fail to post a CQE, then
+		 * Any successful return value will keep the multishot read
+		 * armed, if it's still set. Put our buffer and post a CQE. If
+		 * we fail to post a CQE, or multishot is no longer set, then
 		 * jump to the termination path. This request is then done.
 		 */
 		cflags = io_put_kbuf(req, ret, issue_flags);
+		if (!(req->flags & REQ_F_APOLL_MULTISHOT))
+			goto done;
+
 		rw->len = 0; /* similarly to above, reset len to 0 */
 
 		if (io_req_post_cqe(req, ret, cflags | IORING_CQE_F_MORE)) {
@@ -1003,6 +1007,7 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 	 * Either an error, or we've hit overflow posting the CQE. For any
 	 * multishot request, hitting overflow will terminate it.
 	 */
+done:
 	io_req_set_res(req, ret, cflags);
 	io_req_rw_cleanup(req, issue_flags);
 	if (issue_flags & IO_URING_F_MULTISHOT)