From 934447a603b22d98f45a679115d8402e1efdd0f7 Mon Sep 17 00:00:00 2001
From: Dylan Yudaken <dylany@fb.com>
Date: Thu, 21 Jul 2022 06:13:25 -0700
Subject: [PATCH] io_uring: do not recycle buffer in READV
Git-commit: 934447a603b22d98f45a679115d8402e1efdd0f7
Patch-mainline: v5.19-rc8
References: bsc#1205205
READV cannot recycle buffers as it would lose some of the data required to
reimport that buffer.
Reported-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Fixes: b66e65f41426 ("io_uring: never call io_buffer_select() for a buffer re-select")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220721131325.624788-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
fs/io_uring.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2b7bb62c7805..e8e769be9ed0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1737,6 +1737,14 @@ static void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
(req->flags & REQ_F_PARTIAL_IO))
return;
+ /*
+ * READV uses fields in `struct io_rw` (len/addr) to stash the selected
+ * buffer data. However if that buffer is recycled the original request
+ * data stored in addr is lost. Therefore forbid recycling for now.
+ */
+ if (req->opcode == IORING_OP_READV)
+ return;
+
/*
* We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
* the flag and hence ensure that bl->head doesn't get incremented.
--
2.35.3