[PATCH v2 2/4] io_uring/cmd: introduce IORING_URING_CMD_REISSUE flag

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

Add a flag IORING_URING_CMD_REISSUE that ->uring_cmd() implementations
can use to tell whether this is the first or subsequent issue of the
uring_cmd. This will allow ->uring_cmd() implementations to store
information in the io_uring_cmd's pdu across issues.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 include/linux/io_uring/cmd.h | 2 ++
 io_uring/uring_cmd.c         | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 53408124c1e5..29892f54e0ac 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -6,10 +6,12 @@
 #include <linux/io_uring_types.h>
 #include <linux/blk-mq.h>
 
 /* only top 8 bits of sqe->uring_cmd_flags for kernel internal use */
 #define IORING_URING_CMD_CANCELABLE	(1U << 30)
+/* io_uring_cmd is being issued again */
+#define IORING_URING_CMD_REISSUE	(1U << 31)
 
 struct io_uring_cmd {
 	struct file	*file;
 	const struct io_uring_sqe *sqe;
 	/* callback to defer completions to task context */
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index b228b84a510f..58964a2f8582 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -259,11 +259,15 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
 			req->iopoll_start = ktime_get_ns();
 		}
 	}
 
 	ret = file->f_op->uring_cmd(ioucmd, issue_flags);
-	if (ret == -EAGAIN || ret == -EIOCBQUEUED)
+	if (ret == -EAGAIN) {
+		ioucmd->flags |= IORING_URING_CMD_REISSUE;
+		return ret;
+	}
+	if (ret == -EIOCBQUEUED)
 		return ret;
 	if (ret < 0)
 		req_set_fail(req);
 	io_req_uring_cleanup(req, issue_flags);
 	io_req_set_res(req, ret, 0);
-- 
2.45.2