io_uring: dont remove file from msg_ring reqs

We should not be messing with req->file outside of core paths. Clearing
it makes msg_ring non reentrant, i.e. luckily io_msg_send_fd() fails the
request on failed io_double_lock_ctx() but clearly was originally
intended to do retries instead.

Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e5ac9edadb574fe33f6d727cb8f14ce68262a684.1670384893.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -1799,7 +1799,7 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 		return ret;
 
 	/* If the op doesn't have a file, we're not polling for it */
-	if ((req->ctx->flags & IORING_SETUP_IOPOLL) && req->file)
+	if ((req->ctx->flags & IORING_SETUP_IOPOLL) && def->iopoll_queue)
 		io_iopoll_req_issued(req, issue_flags);
 
 	return 0;

io_uring/msg_ring.c

@@ -167,9 +167,5 @@ int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
 	if (ret < 0)
 		req_set_fail(req);
 	io_req_set_res(req, ret, 0);
-	/* put file to avoid an attempt to IOPOLL the req */
-	if (!(req->flags & REQ_F_FIXED_FILE))
-		io_put_file(req->file);
-	req->file = NULL;
 	return IOU_OK;
 }

io_uring/opdef.c

@@ -63,6 +63,7 @@ const struct io_op_def io_op_defs[] = {
 		.audit_skip		= 1,
 		.ioprio			= 1,
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= sizeof(struct io_async_rw),
 		.name			= "READV",
 		.prep			= io_prep_rw,
@@ -80,6 +81,7 @@ const struct io_op_def io_op_defs[] = {
 		.audit_skip		= 1,
 		.ioprio			= 1,
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= sizeof(struct io_async_rw),
 		.name			= "WRITEV",
 		.prep			= io_prep_rw,
@@ -103,6 +105,7 @@ const struct io_op_def io_op_defs[] = {
 		.audit_skip		= 1,
 		.ioprio			= 1,
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= sizeof(struct io_async_rw),
 		.name			= "READ_FIXED",
 		.prep			= io_prep_rw,
@@ -118,6 +121,7 @@ const struct io_op_def io_op_defs[] = {
 		.audit_skip		= 1,
 		.ioprio			= 1,
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= sizeof(struct io_async_rw),
 		.name			= "WRITE_FIXED",
 		.prep			= io_prep_rw,
@@ -277,6 +281,7 @@ const struct io_op_def io_op_defs[] = {
 		.audit_skip		= 1,
 		.ioprio			= 1,
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= sizeof(struct io_async_rw),
 		.name			= "READ",
 		.prep			= io_prep_rw,
@@ -292,6 +297,7 @@ const struct io_op_def io_op_defs[] = {
 		.audit_skip		= 1,
 		.ioprio			= 1,
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= sizeof(struct io_async_rw),
 		.name			= "WRITE",
 		.prep			= io_prep_rw,
@@ -481,6 +487,7 @@ const struct io_op_def io_op_defs[] = {
 		.plug			= 1,
 		.name			= "URING_CMD",
 		.iopoll			= 1,
+		.iopoll_queue		= 1,
 		.async_size		= uring_cmd_pdu_size(1),
 		.prep			= io_uring_cmd_prep,
 		.issue			= io_uring_cmd,

io_uring/opdef.h

@@ -25,6 +25,8 @@ struct io_op_def {
 	unsigned		ioprio : 1;
 	/* supports iopoll */
 	unsigned		iopoll : 1;
+	/* have to be put into the iopoll list */
+	unsigned		iopoll_queue : 1;
 	/* opcode specific path will handle ->async_data allocation if needed */
 	unsigned		manual_alloc : 1;
 	/* size of async data needed, if any */