[PATCH v3 0/3] io_uring: add splice(2) support

[PATCH v3 0/3] io_uring: add splice(2) support

[Pavel Begunkov]

Not the fastets implementation, but I'd need to stir up/duplicate
splice.c bits to do it more efficiently.

note: rebase on top of the recent inflight patchset.

v2:
- u32 len and SQE layout changes (Jens)
- output file is in sqe->fd for automatic hash_reg_file support
- handle unbound_nonreg_file for the second fd
- file leaks fixed with REQ_F_NEED_CLEANUP
- place SPLICE_F_FD_IN_FIXED in splice flags (Jens)
- loff_t* -> loff_t, -1 means not specified offset

v3: [PATCH 3/3] changes
- fd u32 -> s32 (Stefan Metzmacher)
- add BUILD_BUG_SQE_ELEM() (Stefan Metzmacher)
- accept and ignore ioprio (Stefan Metzmacher)
- off_in -> splice_off_in

Pavel Begunkov (3):
  splice: make do_splice public
  io_uring: add interface for getting files
  io_uring: add splice(2) support

 fs/io_uring.c                 | 175 +++++++++++++++++++++++++++++-----
 fs/splice.c                   |   6 +-
 include/linux/splice.h        |   3 +
 include/uapi/linux/io_uring.h |  14 ++-
 4 files changed, 169 insertions(+), 29 deletions(-)

-- 
2.24.0

[PATCH v3 1/3] splice: make do_splice public

[Pavel Begunkov]

Make do_splice(), so other kernel parts can reuse it

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/splice.c            | 6 +++---
 include/linux/splice.h | 3 +++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 3009652a41c8..6a6f30432688 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1109,9 +1109,9 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
 /*
  * Determine where to splice to/from.
  */
-static long do_splice(struct file *in, loff_t __user *off_in,
-		      struct file *out, loff_t __user *off_out,
-		      size_t len, unsigned int flags)
+long do_splice(struct file *in, loff_t __user *off_in,
+		struct file *out, loff_t __user *off_out,
+		size_t len, unsigned int flags)
 {
 	struct pipe_inode_info *ipipe;
 	struct pipe_inode_info *opipe;
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 74b4911ac16d..ebbbfea48aa0 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -78,6 +78,9 @@ extern ssize_t add_to_pipe(struct pipe_inode_info *,
 			      struct pipe_buffer *);
 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
 				      splice_direct_actor *);
+extern long do_splice(struct file *in, loff_t __user *off_in,
+		      struct file *out, loff_t __user *off_out,
+		      size_t len, unsigned int flags);
 
 /*
  * for dynamic pipe sizing
-- 
2.24.0

[PATCH v3 2/3] io_uring: add interface for getting files

[Pavel Begunkov]

Preparation without functional changes. Adds io_get_file(), that allows
to grab files not only into req->file.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 66 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5ff7c602ad4d..389db6f5568b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1255,6 +1255,15 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
 	return NULL;
 }
 
+static inline void io_put_file(struct io_ring_ctx *ctx, struct file *file,
+			  bool fixed)
+{
+	if (fixed)
+		percpu_ref_put(&ctx->file_data->refs);
+	else
+		fput(file);
+}
+
 static void __io_req_do_free(struct io_kiocb *req)
 {
 	if (likely(!io_is_fallback_req(req)))
@@ -1268,12 +1277,8 @@ static void __io_req_aux_free(struct io_kiocb *req)
 	struct io_ring_ctx *ctx = req->ctx;
 
 	kfree(req->io);
-	if (req->file) {
-		if (req->flags & REQ_F_FIXED_FILE)
-			percpu_ref_put(&ctx->file_data->refs);
-		else
-			fput(req->file);
-	}
+	if (req->file)
+		io_put_file(ctx, req->file, (req->flags & REQ_F_FIXED_FILE));
 
 	io_req_work_drop_env(req);
 }
@@ -4573,41 +4578,52 @@ static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
 	return table->files[index & IORING_FILE_TABLE_MASK];;
 }
 
-static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
-			   const struct io_uring_sqe *sqe)
+static int io_get_file(struct io_submit_state *state, struct io_ring_ctx *ctx,
+			int fd, struct file **out_file, bool fixed)
 {
-	struct io_ring_ctx *ctx = req->ctx;
-	unsigned flags;
-	int fd;
-
-	flags = READ_ONCE(sqe->flags);
-	fd = READ_ONCE(sqe->fd);
-
-	if (!io_req_needs_file(req, fd))
-		return 0;
+	struct file *file;
 
-	if (flags & IOSQE_FIXED_FILE) {
+	if (fixed) {
 		if (unlikely(!ctx->file_data ||
 		    (unsigned) fd >= ctx->nr_user_files))
 			return -EBADF;
 		fd = array_index_nospec(fd, ctx->nr_user_files);
-		req->file = io_file_from_index(ctx, fd);
-		if (!req->file)
+		file = io_file_from_index(ctx, fd);
+		if (!file)
 			return -EBADF;
-		req->flags |= REQ_F_FIXED_FILE;
 		percpu_ref_get(&ctx->file_data->refs);
 	} else {
-		if (req->needs_fixed_file)
-			return -EBADF;
 		trace_io_uring_file_get(ctx, fd);
-		req->file = io_file_get(state, fd);
-		if (unlikely(!req->file))
+		file = io_file_get(state, fd);
+		if (unlikely(!file))
 			return -EBADF;
 	}
 
+	*out_file = file;
 	return 0;
 }
 
+static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
+			   const struct io_uring_sqe *sqe)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned flags;
+	int fd;
+	bool fixed;
+
+	flags = READ_ONCE(sqe->flags);
+	fd = READ_ONCE(sqe->fd);
+
+	if (!io_req_needs_file(req, fd))
+		return 0;
+
+	fixed = (flags & IOSQE_FIXED_FILE);
+	if (unlikely(!fixed && req->needs_fixed_file))
+		return -EBADF;
+
+	return io_get_file(state, ctx, fd, &req->file, fixed);
+}
+
 static int io_grab_files(struct io_kiocb *req)
 {
 	int ret = -EBADF;
-- 
2.24.0

[PATCH v3 3/3] io_uring: add splice(2) support

[Pavel Begunkov]

Add support for splice(2).

- output file is specified as sqe->fd, so it's handled by generic code
- hash_reg_file handled by generic code as well
- len is 32bit, but should be fine
- the fd_in is registered file, when SPLICE_F_FD_IN_FIXED is set, which
is a splice flag (i.e. sqe->splice_flags).

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c                 | 109 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h |  14 ++++-
 2 files changed, 122 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 389db6f5568b..c535d870c23d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -76,6 +76,7 @@
 #include <linux/fadvise.h>
 #include <linux/eventpoll.h>
 #include <linux/fs_struct.h>
+#include <linux/splice.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
@@ -433,6 +434,15 @@ struct io_epoll {
 	struct epoll_event		event;
 };
 
+struct io_splice {
+	struct file			*file_out;
+	struct file			*file_in;
+	loff_t				off_out;
+	loff_t				off_in;
+	u64				len;
+	unsigned int			flags;
+};
+
 struct io_async_connect {
 	struct sockaddr_storage		address;
 };
@@ -546,6 +556,7 @@ struct io_kiocb {
 		struct io_fadvise	fadvise;
 		struct io_madvise	madvise;
 		struct io_epoll		epoll;
+		struct io_splice	splice;
 	};
 
 	struct io_async_ctx		*io;
@@ -746,6 +757,11 @@ static const struct io_op_def io_op_defs[] = {
 		.unbound_nonreg_file	= 1,
 		.file_table		= 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);
@@ -760,6 +776,10 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 static int io_grab_files(struct io_kiocb *req);
 static void io_ring_file_ref_flush(struct fixed_file_data *data);
 static void io_cleanup_req(struct io_kiocb *req);
+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;
 
@@ -2412,6 +2432,77 @@ 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;
+	unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL;
+	int ret;
+
+	if (req->flags & REQ_F_NEED_CLEANUP)
+		return 0;
+
+	sp->file_in = NULL;
+	sp->off_in = READ_ONCE(sqe->splice_off_in);
+	sp->off_out = READ_ONCE(sqe->off);
+	sp->len = READ_ONCE(sqe->len);
+	sp->flags = READ_ONCE(sqe->splice_flags);
+
+	if (unlikely(sp->flags & ~valid_flags))
+		return -EINVAL;
+
+	ret = io_get_file(NULL, req->ctx, READ_ONCE(sqe->splice_fd_in),
+			   &sp->file_in, (sp->flags & SPLICE_F_FD_IN_FIXED));
+	if (ret)
+		return ret;
+	req->flags |= REQ_F_NEED_CLEANUP;
+
+	if (!S_ISREG(file_inode(sp->file_in)->i_mode))
+		req->work.flags |= IO_WQ_WORK_UNBOUND;
+
+	return 0;
+}
+
+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 & ~SPLICE_F_FD_IN_FIXED;
+	loff_t *poff_in, *poff_out;
+	long ret;
+
+	if (force_nonblock) {
+		if (io_splice_punt(in) || io_splice_punt(out))
+			return -EAGAIN;
+		flags |= SPLICE_F_NONBLOCK;
+	}
+
+	poff_in = (sp->off_in == -1) ? NULL : &sp->off_in;
+	poff_out = (sp->off_out == -1) ? NULL : &sp->off_out;
+	ret = do_splice(in, poff_in, out, poff_out, sp->len, flags);
+	if (force_nonblock && ret == -EAGAIN)
+		return -EAGAIN;
+
+	io_put_file(req->ctx, in, (sp->flags & SPLICE_F_FD_IN_FIXED));
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+
+	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.
  */
@@ -4227,6 +4318,9 @@ static int io_req_defer_prep(struct io_kiocb *req,
 	case IORING_OP_EPOLL_CTL:
 		ret = io_epoll_ctl_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);
@@ -4289,6 +4383,10 @@ static void io_cleanup_req(struct io_kiocb *req)
 	case IORING_OP_STATX:
 		putname(req->open.filename);
 		break;
+	case IORING_OP_SPLICE:
+		io_put_file(req->ctx, req->splice.file_in,
+			    (req->splice.flags & SPLICE_F_FD_IN_FIXED));
+		break;
 	}
 
 	req->flags &= ~REQ_F_NEED_CLEANUP;
@@ -4492,6 +4590,14 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		}
 		ret = io_epoll_ctl(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;
@@ -7227,6 +7333,7 @@ static int __init io_uring_init(void)
 	BUILD_BUG_SQE_ELEM(8,  __u64,  off);
 	BUILD_BUG_SQE_ELEM(8,  __u64,  addr2);
 	BUILD_BUG_SQE_ELEM(16, __u64,  addr);
+	BUILD_BUG_SQE_ELEM(16, __u64,  splice_off_in);
 	BUILD_BUG_SQE_ELEM(24, __u32,  len);
 	BUILD_BUG_SQE_ELEM(28,     __kernel_rwf_t, rw_flags);
 	BUILD_BUG_SQE_ELEM(28, /* compat */   int, rw_flags);
@@ -7241,9 +7348,11 @@ static int __init io_uring_init(void)
 	BUILD_BUG_SQE_ELEM(28, __u32,  open_flags);
 	BUILD_BUG_SQE_ELEM(28, __u32,  statx_flags);
 	BUILD_BUG_SQE_ELEM(28, __u32,  fadvise_advice);
+	BUILD_BUG_SQE_ELEM(28, __u32,  splice_flags);
 	BUILD_BUG_SQE_ELEM(32, __u64,  user_data);
 	BUILD_BUG_SQE_ELEM(40, __u16,  buf_index);
 	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
+	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
 
 	BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST);
 	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 3f7961c1c243..08891cc1c1e7 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -23,7 +23,10 @@ struct io_uring_sqe {
 		__u64	off;	/* offset into file */
 		__u64	addr2;
 	};
-	__u64	addr;		/* pointer to buffer or iovecs */
+	union {
+		__u64	addr;	/* pointer to buffer or iovecs */
+		__u64	splice_off_in;
+	};
 	__u32	len;		/* buffer size or number of iovecs */
 	union {
 		__kernel_rwf_t	rw_flags;
@@ -37,6 +40,7 @@ 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 {
@@ -45,6 +49,7 @@ struct io_uring_sqe {
 			__u16	buf_index;
 			/* personality to use, if used */
 			__u16	personality;
+			__s32	splice_fd_in;
 		};
 		__u64	__pad2[3];
 	};
@@ -113,6 +118,7 @@ enum {
 	IORING_OP_RECV,
 	IORING_OP_OPENAT2,
 	IORING_OP_EPOLL_CTL,
+	IORING_OP_SPLICE,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
@@ -128,6 +134,12 @@ enum {
  */
 #define IORING_TIMEOUT_ABS	(1U << 0)
 
+/*
+ * sqe->splice_flags
+ * extends splice(2) flags
+ */
+#define SPLICE_F_FD_IN_FIXED	(1U << 31) /* the last bit of __u32 */
+
 /*
  * IO completion data structure (Completion Queue Entry)
  */
-- 
2.24.0