[PATCH v9 07/11] io_uring: inline read/write attributes and PI

[Anuj Gupta]

Add the ability to place attributes inline within SQE.
Carve a new field that can accommodate 16 attribute flags:
	__u16 attr_inline_flags;

Currently ATTR_FLAG_PI is defined, and future flags can be or-ed to specify
the attributes that are placed inline.

When ATTR_FLAG_PI is passed, application should also setup SQE128 ring
and place PI information (i.e., struct io_uring_attr_pi) in the first
32b of second SQE.

Signed-off-by: Anuj Gupta <anuj20.g at samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k at samsung.com>
---
 include/uapi/linux/io_uring.h | 13 +++++++++++-
 io_uring/io_uring.c           |  6 +++++-
 io_uring/rw.c                 | 38 ++++++++++++++++++++++++++++++++---
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 2e6808f6ba28..9c290c16e543 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -93,9 +93,11 @@ struct io_uring_sqe {
 			__u16	__pad3[1];
 		};
 		struct {
+			/* used when extra attribute is passed inline SQE/SQE128 */
+			__u16	attr_inline_flags;
 			/* number of elements in the attribute vector */
 			__u8	nr_attr_indirect;
-			__u8	__pad4[3];
+			__u8	__pad4[1];
 		};
 	};
 	union {
@@ -126,6 +128,8 @@ struct io_uring_attr_vec {
 	__u64			addr;
 };
 
+/* sqe->attr_inline_flags */
+#define ATTR_FLAG_PI	(1U << ATTR_TYPE_PI)
 /* PI attribute information */
 struct io_uring_attr_pi {
 		__u16	flags;
@@ -136,6 +140,13 @@ struct io_uring_attr_pi {
 		__u64	rsvd;
 };
 
+/* Second half of SQE128 for IORING_OP_READ/WRITE */
+struct io_uring_sqe_ext {
+	/* if sqe->attr_inline_flags has ATTR_PI, first 32 bytes are for PI */
+	struct io_uring_attr_pi	rw_pi;
+	__u64			rsvd1[4];
+};
+
 /*
  * If sqe->file_index is set to this for opcodes that instantiate a new
  * direct descriptor (like openat/openat2/accept), then io_uring will allocate
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index e32dd118d7c8..3f975befe82e 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3866,8 +3866,9 @@ 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, __u16,  attr_inline_flags);
 	BUILD_BUG_SQE_ELEM(46, __u16,  __pad3[0]);
-	BUILD_BUG_SQE_ELEM(44, __u8,   nr_attr_indirect);
+	BUILD_BUG_SQE_ELEM(46, __u8,   nr_attr_indirect);
 	BUILD_BUG_SQE_ELEM(48, __u64,  addr3);
 	BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
 	BUILD_BUG_SQE_ELEM(56, __u64,  __pad2);
@@ -3894,6 +3895,9 @@ static int __init io_uring_init(void)
 	/* top 8bits are for internal use */
 	BUILD_BUG_ON((IORING_URING_CMD_MASK & 0xff000000) != 0);
 
+	BUILD_BUG_ON(sizeof(struct io_uring_sqe_ext) !=
+		     sizeof(struct io_uring_sqe));
+
 	io_uring_optable_init();
 
 	/*
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 93d7451b9370..d2d403ca6eb3 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -269,6 +269,11 @@ static inline void io_meta_restore(struct io_async_rw *io)
 	iov_iter_restore(&io->meta.iter, &io->meta_state.iter_meta);
 }
 
+static inline const void *io_uring_sqe_ext(const struct io_uring_sqe *sqe)
+{
+	return (sqe + 1);
+}
+
 static int io_prep_rw_pi(struct io_kiocb *req, struct io_rw *rw, int ddir,
 			 const struct io_uring_attr_pi *pi_attr)
 {
@@ -343,11 +348,34 @@ static int io_prep_attr_vec(struct io_kiocb *req, struct io_rw *rw, int ddir,
 	return 0;
 }
 
+static int io_prep_inline_attr(struct io_kiocb *req, struct io_rw *rw,
+			       const struct io_uring_sqe *sqe, int ddir,
+			       u16 attr_flags)
+{
+	const struct io_uring_sqe_ext *sqe_ext;
+	const struct io_uring_attr_pi *pi_attr;
+
+	if (!(attr_flags & ATTR_FLAG_PI))
+		return -EINVAL;
+
+	if (!(req->ctx->flags & IORING_SETUP_SQE128))
+		return -EINVAL;
+
+	sqe_ext = io_uring_sqe_ext(sqe);
+	if (READ_ONCE(sqe_ext->rsvd1[0]) || READ_ONCE(sqe_ext->rsvd1[1])
+	    || READ_ONCE(sqe_ext->rsvd1[2]) || READ_ONCE(sqe_ext->rsvd1[3]))
+		return -EINVAL;
+
+	pi_attr = &sqe_ext->rw_pi;
+	return io_prep_rw_pi(req, rw, ddir, pi_attr);
+}
+
 static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		      int ddir, bool do_import)
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	unsigned ioprio;
+	u16 attr_flags;
 	u8 nr_attr_indirect;
 	int ret;
 
@@ -376,12 +404,16 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (unlikely(ret))
 		return ret;
 
+	attr_flags = READ_ONCE(sqe->attr_inline_flags);
 	nr_attr_indirect = READ_ONCE(sqe->nr_attr_indirect);
-	if (nr_attr_indirect) {
+	if (attr_flags) {
+		if (READ_ONCE(sqe->__pad4[0]) || nr_attr_indirect)
+			return -EINVAL;
+		ret = io_prep_inline_attr(req, rw, sqe, ddir, attr_flags);
+	} else if (nr_attr_indirect) {
 		u64 attr_vec_usr_addr = READ_ONCE(sqe->attr_vec_addr);
 
-		if (READ_ONCE(sqe->__pad4[0]) || READ_ONCE(sqe->__pad4[1]) ||
-		    READ_ONCE(sqe->__pad4[2]))
+		if (READ_ONCE(sqe->__pad4[0]))
 			return -EINVAL;
 
 		ret = io_prep_attr_vec(req, rw, ddir, attr_vec_usr_addr,
-- 
2.25.1