[PATCHv12 07/12] io_uring: enable per-io write streams

Keith Busch
2024-12-06T22:30:05Z

From: Keith Busch <kbusch@kernel.org>

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

__u8 write_stream;

The __u8 type matches the size the filesystems and block layer support.

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: Keith Busch <kbusch@kernel.org>
---
include/uapi/linux/io_uring.h | 4 ++++
io_uring/io_uring.c | 2 ++
io_uring/rw.c | 1 +
3 files changed, 7 insertions(+)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 38f0d6b10eaf7..986a480e3b9c2 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -92,6 +92,10 @@ struct io_uring_sqe {
__u16 addr_len;
__u16 __pad3[1];
};
+ struct {
+ __u8 write_stream;
+ __u8 __pad4[3];
+ };
};
union {
struct {
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index a8cbe674e5d63..978d0617d7af8 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(44, __s32, splice_fd_in);
BUILD_BUG_SQE_ELEM(44, __u32, file_index);
BUILD_BUG_SQE_ELEM(44, __u16, addr_len);
+ BUILD_BUG_SQE_ELEM(44, __u8, write_stream);
+ BUILD_BUG_SQE_ELEM(45, __u8, __pad4[0]);
BUILD_BUG_SQE_ELEM(46, __u16, __pad3[0]);
BUILD_BUG_SQE_ELEM(48, __u64, addr3);
BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 04e4467ab0ee8..b8aa2dfcbf48c 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -322,6 +322,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
}
rw->kiocb.dio_complete = NULL;
rw->kiocb.ki_flags = 0;
+ rw->kiocb.ki_write_stream = READ_ONCE(sqe->write_stream);

rw->addr = READ_ONCE(sqe->addr);
rw->len = READ_ONCE(sqe->len);
--
2.43.5