[PATCH 3/3] io_uring: add splice(2) support

[Pavel Begunkov]

Add support for splice(2). Nothing new, just reuse do_splice().

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
 fs/io_uring.c                 | 86 +++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h | 16 ++++++-
 2 files changed, 100 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e9e4aee0fb99..44ec9c63c41d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -74,6 +74,7 @@
 #include <linux/namei.h>
 #include <linux/fsnotify.h>
 #include <linux/fadvise.h>
+#include <linux/splice.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
@@ -373,6 +374,15 @@ struct io_rw {
 	u64				len;
 };
 
+struct io_splice {
+	struct file			*file_in;
+	struct file			*file_out;
+	loff_t __user			*off_in;
+	loff_t __user			*off_out;
+	u64				len;
+	unsigned int			flags;
+};
+
 struct io_connect {
 	struct file			*file;
 	struct sockaddr __user		*addr;
@@ -534,6 +544,7 @@ struct io_kiocb {
 		struct io_files_update	files_update;
 		struct io_fadvise	fadvise;
 		struct io_madvise	madvise;
+		struct io_splice	splice;
 	};
 
 	struct io_async_ctx		*io;
@@ -719,6 +730,11 @@ static const struct io_op_def io_op_defs[] = {
 		.needs_file		= 1,
 		.fd_non_neg		= 1,
 	},
+	[IORING_OP_SPLICE] = {
+		.needs_file		= 1,
+		.hash_reg_file		= 1,
+		.unbound_nonreg_file	= 1,
+	}
 };
 
 static void io_wq_submit_work(struct io_wq_work **workptr);
@@ -730,6 +746,10 @@ static void io_queue_linked_timeout(struct io_kiocb *req);
 static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 				 struct io_uring_files_update *ip,
 				 unsigned nr_args);
+static int io_get_file(struct io_submit_state *state,
+		       struct io_ring_ctx *ctx,
+		       int fd, struct file **out_file,
+		       bool fixed);
 
 static struct kmem_cache *req_cachep;
 
@@ -2322,6 +2342,61 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
 	return ret;
 }
 
+static int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_splice* sp = &req->splice;
+
+	sp->file_out = NULL;
+	sp->off_in = u64_to_user_ptr(READ_ONCE(sqe->off));
+	sp->off_out = u64_to_user_ptr(READ_ONCE(sqe->off_out));
+	sp->len = READ_ONCE(sqe->splice_len);
+	sp->flags = READ_ONCE(sqe->splice_flags);
+
+	if (unlikely(READ_ONCE(sqe->ioprio) || (sp->flags & ~SPLICE_F_ALL)))
+		return -EINVAL;
+
+	return io_get_file(NULL, req->ctx, READ_ONCE(sqe->fd_out),
+			   &sp->file_out, (sp->flags & IOSQE_SPLICE_FIXED_OUT));
+}
+
+static bool io_splice_punt(struct file *file)
+{
+	if (get_pipe_info(file))
+		return false;
+	if (!io_file_supports_async(file))
+		return true;
+	return !(file->f_mode & O_NONBLOCK);
+}
+
+static int io_splice(struct io_kiocb *req, struct io_kiocb **nxt,
+		     bool force_nonblock)
+{
+	struct io_splice* sp = &req->splice;
+	struct file *in = sp->file_in;
+	struct file *out = sp->file_out;
+	unsigned int flags = sp->flags;
+	long ret;
+
+	if (force_nonblock) {
+		if (io_splice_punt(in) || io_splice_punt(out)) {
+			req->flags |= REQ_F_MUST_PUNT;
+			return -EAGAIN;
+		}
+		flags |= SPLICE_F_NONBLOCK;
+	}
+
+	ret = do_splice(in, sp->off_in, out, sp->off_out, sp->len, flags);
+	if (force_nonblock && ret == -EAGAIN)
+		return -EAGAIN;
+
+	io_put_file(req->ctx, out, (flags & IOSQE_SPLICE_FIXED_OUT));
+	io_cqring_add_event(req, ret);
+	if (ret != sp->len)
+		req_set_fail_links(req);
+	io_put_req_find_next(req, nxt);
+	return 0;
+}
+
 /*
  * IORING_OP_NOP just posts a completion event, nothing else.
  */
@@ -4044,6 +4119,9 @@ static int io_req_defer_prep(struct io_kiocb *req,
 	case IORING_OP_OPENAT2:
 		ret = io_openat2_prep(req, sqe);
 		break;
+	case IORING_OP_SPLICE:
+		ret = io_splice_prep(req, sqe);
+		break;
 	default:
 		printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
 				req->opcode);
@@ -4272,6 +4350,14 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		}
 		ret = io_openat2(req, nxt, force_nonblock);
 		break;
+	case IORING_OP_SPLICE:
+		if (sqe) {
+			ret = io_splice_prep(req, sqe);
+			if (ret < 0)
+				break;
+		}
+		ret = io_splice(req, nxt, force_nonblock);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 57d05cc5e271..f234b13e7ed3 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -23,8 +23,14 @@ struct io_uring_sqe {
 		__u64	off;	/* offset into file */
 		__u64	addr2;
 	};
-	__u64	addr;		/* pointer to buffer or iovecs */
-	__u32	len;		/* buffer size or number of iovecs */
+	union {
+		__u64	addr;		/* pointer to buffer or iovecs */
+		__u64	off_out;
+	};
+	union {
+		__u32	len;	/* buffer size or number of iovecs */
+		__s32	fd_out;
+	};
 	union {
 		__kernel_rwf_t	rw_flags;
 		__u32		fsync_flags;
@@ -37,10 +43,12 @@ struct io_uring_sqe {
 		__u32		open_flags;
 		__u32		statx_flags;
 		__u32		fadvise_advice;
+		__u32		splice_flags;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
 	union {
 		__u16	buf_index;	/* index into fixed buffers, if used */
+		__u64	splice_len;
 		__u64	__pad2[3];
 	};
 };
@@ -67,6 +75,9 @@ enum {
 /* always go async */
 #define IOSQE_ASYNC		(1U << IOSQE_ASYNC_BIT)
 
+/* op custom flags */
+#define IOSQE_SPLICE_FIXED_OUT	(1U << 16)
+
 /*
  * io_uring_setup() flags
  */
@@ -106,6 +117,7 @@ enum {
 	IORING_OP_SEND,
 	IORING_OP_RECV,
 	IORING_OP_OPENAT2,
+	IORING_OP_SPLICE,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
-- 
2.24.0