[PATCH 2/9] io_uring: support user sqe ext flags

[Ming Lei <ming.lei@redhat.com>]

sqe->flags is u8, and now we have used 7 bits, so take the last one for
extending purpose.

If bit7(IOSQE_HAS_EXT_FLAGS_BIT) is 1, it means this sqe carries ext flags
from the last byte(.ext_flags), or bit23~bit16 of sqe->uring_cmd_flags for
IORING_OP_URING_CMD.

io_slot_flags() return value is converted to `ULL` because the affected bits
are beyond 32bit now.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/io_uring_types.h |  6 ++++--
 include/uapi/linux/io_uring.h  | 13 +++++++++++++
 io_uring/filetable.h           |  2 +-
 io_uring/io_uring.c            | 14 +++++++++++++-
 io_uring/uring_cmd.c           |  3 ++-
 5 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 3e72fa52f1e3..67347e5d06ec 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -435,6 +435,7 @@ struct io_tw_state {
 };
 
 enum {
+	/* 1st byte is from sqe->flags, and 2nd is from sqe ext_flags */
 	REQ_F_FIXED_FILE_BIT	= IOSQE_FIXED_FILE_BIT,
 	REQ_F_IO_DRAIN_BIT	= IOSQE_IO_DRAIN_BIT,
 	REQ_F_LINK_BIT		= IOSQE_IO_LINK_BIT,
@@ -442,9 +443,10 @@ enum {
 	REQ_F_FORCE_ASYNC_BIT	= IOSQE_ASYNC_BIT,
 	REQ_F_BUFFER_SELECT_BIT	= IOSQE_BUFFER_SELECT_BIT,
 	REQ_F_CQE_SKIP_BIT	= IOSQE_CQE_SKIP_SUCCESS_BIT,
+	REQ_F_SQE_EXT_FLAGS_BIT	= IOSQE_HAS_EXT_FLAGS_BIT,
 
-	/* first byte is taken by user flags, shift it to not overlap */
-	REQ_F_FAIL_BIT		= 8,
+	/* first 2 bytes are taken by user flags, shift it to not overlap */
+	REQ_F_FAIL_BIT		= 16,
 	REQ_F_INFLIGHT_BIT,
 	REQ_F_CUR_POS_BIT,
 	REQ_F_NOWAIT_BIT,
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index a7f847543a7f..4847d7cf1ac9 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -98,6 +98,10 @@ struct io_uring_sqe {
 			__u64	__pad2[1];
 		};
 		__u64	optval;
+		struct {
+			__u8	__pad4[15];
+			__u8	ext_flags;
+		};
 		/*
 		 * If the ring is initialized with IORING_SETUP_SQE128, then
 		 * this field is used for 80 bytes of arbitrary command data
@@ -123,6 +127,7 @@ enum io_uring_sqe_flags_bit {
 	IOSQE_ASYNC_BIT,
 	IOSQE_BUFFER_SELECT_BIT,
 	IOSQE_CQE_SKIP_SUCCESS_BIT,
+	IOSQE_HAS_EXT_FLAGS_BIT,
 };
 
 /*
@@ -142,6 +147,11 @@ enum io_uring_sqe_flags_bit {
 #define IOSQE_BUFFER_SELECT	(1U << IOSQE_BUFFER_SELECT_BIT)
 /* don't post CQE if request succeeded */
 #define IOSQE_CQE_SKIP_SUCCESS	(1U << IOSQE_CQE_SKIP_SUCCESS_BIT)
+/*
+ * sqe ext flags carried in the last byte, or bit23~bit16 of
+ * sqe->uring_cmd_flags for IORING_URING_CMD.
+ */
+#define IOSQE_HAS_EXT_FLAGS	(1U << IOSQE_HAS_EXT_FLAGS_BIT)
 
 /*
  * io_uring_setup() flags
@@ -263,11 +273,14 @@ enum io_uring_op {
 
 /*
  * sqe->uring_cmd_flags		top 8bits aren't available for userspace
+ * bit31 ~ bit24		kernel internal usage
+ * bit23 ~ bit16		sqe ext flags
  * IORING_URING_CMD_FIXED	use registered buffer; pass this flag
  *				along with setting sqe->buf_index.
  */
 #define IORING_URING_CMD_FIXED	(1U << 0)
 #define IORING_URING_CMD_MASK	IORING_URING_CMD_FIXED
+#define IORING_URING_CMD_EXT_MASK	0x00ff0000
 
 
 /*
diff --git a/io_uring/filetable.h b/io_uring/filetable.h
index b2435c4dca1f..d25247c9b9f5 100644
--- a/io_uring/filetable.h
+++ b/io_uring/filetable.h
@@ -43,7 +43,7 @@ io_fixed_file_slot(struct io_file_table *table, unsigned i)
 #define FFS_ISREG		0x2UL
 #define FFS_MASK		~(FFS_NOWAIT|FFS_ISREG)
 
-static inline unsigned int io_slot_flags(struct io_fixed_file *slot)
+static inline unsigned long io_slot_flags(struct io_fixed_file *slot)
 {
 	return (slot->file_ptr & ~FFS_MASK) << REQ_F_SUPPORT_NOWAIT_BIT;
 }
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 8df9ad010803..6d4def11aebf 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -109,7 +109,8 @@
 			  IOSQE_IO_HARDLINK | IOSQE_ASYNC)
 
 #define SQE_VALID_FLAGS	(SQE_COMMON_FLAGS | IOSQE_BUFFER_SELECT | \
-			IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS)
+			IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS | \
+			IOSQE_HAS_EXT_FLAGS)
 
 #define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \
 				REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS | \
@@ -2080,6 +2081,17 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		/* enforce forwards compatibility on users */
 		if (sqe_flags & ~SQE_VALID_FLAGS)
 			return io_init_fail_req(req, -EINVAL);
+		if (sqe_flags & IOSQE_HAS_EXT_FLAGS) {
+			u32 sqe_ext_flags;
+
+			if (opcode != IORING_OP_URING_CMD)
+				sqe_ext_flags = READ_ONCE(sqe->ext_flags);
+			else
+				sqe_ext_flags = (READ_ONCE(sqe->uring_cmd_flags)
+					& IORING_URING_CMD_EXT_MASK) >> 16;
+			req->flags |= sqe_ext_flags << 8;
+		}
+
 		if (sqe_flags & IOSQE_BUFFER_SELECT) {
 			if (!def->buffer_select)
 				return io_init_fail_req(req, -EOPNOTSUPP);
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 334d31dd6628..43b71f29e7b3 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -202,7 +202,8 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (sqe->__pad1)
 		return -EINVAL;
 
-	ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags);
+	ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags) &
+		~IORING_URING_CMD_EXT_MASK;
 	if (ioucmd->flags & ~IORING_URING_CMD_MASK)
 		return -EINVAL;
 
-- 
2.42.0