[PATCH 03/15] io_uring: enable passing a per-io write stream

[Christoph Hellwig]

From: Kanchan Joshi <joshi.k at samsung.com>

Allow userspace to pass a per-I/O write stream in the SQE:

	__u16 write_stream;

Application can query the supported values from the statx
max_write_streams field.  Unsupported values are ignored by
file operations that do not support write streams or rejected
with an error by those that support them.

Signed-off-by: Kanchan Joshi <joshi.k at samsung.com>
Signed-off-by: Nitesh Shetty <nj.shetty at samsung.com>
Signed-off-by: Keith Busch <kbusch at kernel.org>
[hch: s/write_hints/write_streams/g]
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 include/uapi/linux/io_uring.h | 4 ++++
 io_uring/io_uring.c           | 2 ++
 io_uring/rw.c                 | 2 +-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index aac9a4f8fa9a..7a6a1b3726d3 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -98,6 +98,10 @@ struct io_uring_sqe {
 			__u64	addr3;
 			__u64	__pad2[1];
 		};
+		struct {
+			__u64	__pad4[1];
+			__u16	write_stream;
+		};
 		__u64	optval;
 		/*
 		 * If the ring is initialized with IORING_SETUP_SQE128, then
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index da8fd460977b..a54da2dd83a1 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3868,6 +3868,8 @@ static int __init io_uring_init(void)
 	BUILD_BUG_SQE_ELEM(46, __u16,  __pad3[0]);
 	BUILD_BUG_SQE_ELEM(48, __u64,  addr3);
 	BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
+	BUILD_BUG_SQE_ELEM(48, __u64,  __pad4);
+	BUILD_BUG_SQE_ELEM(56, __u16,  write_stream);
 	BUILD_BUG_SQE_ELEM(56, __u64,  __pad2);
 
 	BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
diff --git a/io_uring/rw.c b/io_uring/rw.c
index cce8bc2ecd3f..88a5b5f65a9b 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -279,7 +279,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		rw->kiocb.ki_ioprio = get_current_ioprio();
 	}
 	rw->kiocb.dio_complete = NULL;
-
+	rw->kiocb.ki_write_stream = READ_ONCE(sqe->write_stream);
 	rw->addr = READ_ONCE(sqe->addr);
 	rw->len = READ_ONCE(sqe->len);
 	rw->flags = READ_ONCE(sqe->rw_flags);
-- 
2.45.2