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authorLinus Torvalds <torvalds@linux-foundation.org>2019-03-08 14:48:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-08 14:48:40 -0800
commit38e7571c07be01f9f19b355a9306a4e3d5cb0f5b (patch)
tree48812ba46a6fe37ee59d31e0de418f336bbb15ca /include/uapi
parent80201fe175cbf7f3e372f53eba0a881a702ad926 (diff)
parent21b4aa5d20fd07207e73270cadffed5c63fb4343 (diff)
Merge tag 'io_uring-2019-03-06' of git://git.kernel.dk/linux-block
Pull io_uring IO interface from Jens Axboe: "Second attempt at adding the io_uring interface. Since the first one, we've added basic unit testing of the three system calls, that resides in liburing like the other unit tests that we have so far. It'll take a while to get full coverage of it, but we're working towards it. I've also added two basic test programs to tools/io_uring. One uses the raw interface and has support for all the various features that io_uring supports outside of standard IO, like fixed files, fixed IO buffers, and polled IO. The other uses the liburing API, and is a simplified version of cp(1). This adds support for a new IO interface, io_uring. io_uring allows an application to communicate with the kernel through two rings, the submission queue (SQ) and completion queue (CQ) ring. This allows for very efficient handling of IOs, see the v5 posting for some basic numbers: https://lore.kernel.org/linux-block/20190116175003.17880-1-axboe@kernel.dk/ Outside of just efficiency, the interface is also flexible and extendable, and allows for future use cases like the upcoming NVMe key-value store API, networked IO, and so on. It also supports async buffered IO, something that we've always failed to support in the kernel. Outside of basic IO features, it supports async polled IO as well. This particular feature has already been tested at Facebook months ago for flash storage boxes, with 25-33% improvements. It makes polled IO actually useful for real world use cases, where even basic flash sees a nice win in terms of efficiency, latency, and performance. These boxes were IOPS bound before, now they are not. This series adds three new system calls. One for setting up an io_uring instance (io_uring_setup(2)), one for submitting/completing IO (io_uring_enter(2)), and one for aux functions like registrating file sets, buffers, etc (io_uring_register(2)). Through the help of Arnd, I've coordinated the syscall numbers so merge on that front should be painless. Jon did a writeup of the interface a while back, which (except for minor details that have been tweaked) is still accurate. Find that here: https://lwn.net/Articles/776703/ Huge thanks to Al Viro for helping getting the reference cycle code correct, and to Jann Horn for his extensive reviews focused on both security and bugs in general. There's a userspace library that provides basic functionality for applications that don't need or want to care about how to fiddle with the rings directly. It has helpers to allow applications to easily set up an io_uring instance, and submit/complete IO through it without knowing about the intricacies of the rings. It also includes man pages (thanks to Jeff Moyer), and will continue to grow support helper functions and features as time progresses. Find it here: git://git.kernel.dk/liburing Fio has full support for the raw interface, both in the form of an IO engine (io_uring), but also with a small test application (t/io_uring) that can exercise and benchmark the interface" * tag 'io_uring-2019-03-06' of git://git.kernel.dk/linux-block: io_uring: add a few test tools io_uring: allow workqueue item to handle multiple buffered requests io_uring: add support for IORING_OP_POLL io_uring: add io_kiocb ref count io_uring: add submission polling io_uring: add file set registration net: split out functions related to registering inflight socket files io_uring: add support for pre-mapped user IO buffers block: implement bio helper to add iter bvec pages to bio io_uring: batch io_kiocb allocation io_uring: use fget/fput_many() for file references fs: add fget_many() and fput_many() io_uring: support for IO polling io_uring: add fsync support Add io_uring IO interface
Diffstat (limited to 'include/uapi')
-rw-r--r--include/uapi/asm-generic/unistd.h9
-rw-r--r--include/uapi/linux/io_uring.h137
2 files changed, 145 insertions, 1 deletions
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 12cdf611d217..bf4624efe5e6 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -824,8 +824,15 @@ __SYSCALL(__NR_futex_time64, sys_futex)
__SYSCALL(__NR_sched_rr_get_interval_time64, sys_sched_rr_get_interval)
#endif
+#define __NR_io_uring_setup 425
+__SYSCALL(__NR_io_uring_setup, sys_io_uring_setup)
+#define __NR_io_uring_enter 426
+__SYSCALL(__NR_io_uring_enter, sys_io_uring_enter)
+#define __NR_io_uring_register 427
+__SYSCALL(__NR_io_uring_register, sys_io_uring_register)
+
#undef __NR_syscalls
-#define __NR_syscalls 424
+#define __NR_syscalls 428
/*
* 32 bit systems traditionally used different
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
new file mode 100644
index 000000000000..e23408692118
--- /dev/null
+++ b/include/uapi/linux/io_uring.h
@@ -0,0 +1,137 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Header file for the io_uring interface.
+ *
+ * Copyright (C) 2019 Jens Axboe
+ * Copyright (C) 2019 Christoph Hellwig
+ */
+#ifndef LINUX_IO_URING_H
+#define LINUX_IO_URING_H
+
+#include <linux/fs.h>
+#include <linux/types.h>
+
+/*
+ * IO submission data structure (Submission Queue Entry)
+ */
+struct io_uring_sqe {
+ __u8 opcode; /* type of operation for this sqe */
+ __u8 flags; /* IOSQE_ flags */
+ __u16 ioprio; /* ioprio for the request */
+ __s32 fd; /* file descriptor to do IO on */
+ __u64 off; /* offset into file */
+ __u64 addr; /* pointer to buffer or iovecs */
+ __u32 len; /* buffer size or number of iovecs */
+ union {
+ __kernel_rwf_t rw_flags;
+ __u32 fsync_flags;
+ __u16 poll_events;
+ };
+ __u64 user_data; /* data to be passed back at completion time */
+ union {
+ __u16 buf_index; /* index into fixed buffers, if used */
+ __u64 __pad2[3];
+ };
+};
+
+/*
+ * sqe->flags
+ */
+#define IOSQE_FIXED_FILE (1U << 0) /* use fixed fileset */
+
+/*
+ * io_uring_setup() flags
+ */
+#define IORING_SETUP_IOPOLL (1U << 0) /* io_context is polled */
+#define IORING_SETUP_SQPOLL (1U << 1) /* SQ poll thread */
+#define IORING_SETUP_SQ_AFF (1U << 2) /* sq_thread_cpu is valid */
+
+#define IORING_OP_NOP 0
+#define IORING_OP_READV 1
+#define IORING_OP_WRITEV 2
+#define IORING_OP_FSYNC 3
+#define IORING_OP_READ_FIXED 4
+#define IORING_OP_WRITE_FIXED 5
+#define IORING_OP_POLL_ADD 6
+#define IORING_OP_POLL_REMOVE 7
+
+/*
+ * sqe->fsync_flags
+ */
+#define IORING_FSYNC_DATASYNC (1U << 0)
+
+/*
+ * IO completion data structure (Completion Queue Entry)
+ */
+struct io_uring_cqe {
+ __u64 user_data; /* sqe->data submission passed back */
+ __s32 res; /* result code for this event */
+ __u32 flags;
+};
+
+/*
+ * Magic offsets for the application to mmap the data it needs
+ */
+#define IORING_OFF_SQ_RING 0ULL
+#define IORING_OFF_CQ_RING 0x8000000ULL
+#define IORING_OFF_SQES 0x10000000ULL
+
+/*
+ * Filled with the offset for mmap(2)
+ */
+struct io_sqring_offsets {
+ __u32 head;
+ __u32 tail;
+ __u32 ring_mask;
+ __u32 ring_entries;
+ __u32 flags;
+ __u32 dropped;
+ __u32 array;
+ __u32 resv1;
+ __u64 resv2;
+};
+
+/*
+ * sq_ring->flags
+ */
+#define IORING_SQ_NEED_WAKEUP (1U << 0) /* needs io_uring_enter wakeup */
+
+struct io_cqring_offsets {
+ __u32 head;
+ __u32 tail;
+ __u32 ring_mask;
+ __u32 ring_entries;
+ __u32 overflow;
+ __u32 cqes;
+ __u64 resv[2];
+};
+
+/*
+ * io_uring_enter(2) flags
+ */
+#define IORING_ENTER_GETEVENTS (1U << 0)
+#define IORING_ENTER_SQ_WAKEUP (1U << 1)
+
+/*
+ * Passed in for io_uring_setup(2). Copied back with updated info on success
+ */
+struct io_uring_params {
+ __u32 sq_entries;
+ __u32 cq_entries;
+ __u32 flags;
+ __u32 sq_thread_cpu;
+ __u32 sq_thread_idle;
+ __u32 resv[5];
+ struct io_sqring_offsets sq_off;
+ struct io_cqring_offsets cq_off;
+};
+
+/*
+ * io_uring_register(2) opcodes and arguments
+ */
+#define IORING_REGISTER_BUFFERS 0
+#define IORING_UNREGISTER_BUFFERS 1
+#define IORING_REGISTER_FILES 2
+#define IORING_UNREGISTER_FILES 3
+
+#endif