1 /* SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) OR MIT */
2 /*
3  * Header file for the io_uring interface.
4  *
5  * Copyright (C) 2019 Jens Axboe
6  * Copyright (C) 2019 Christoph Hellwig
7  */
8 #ifndef LINUX_IO_URING_H
9 #define LINUX_IO_URING_H
10 
11 #include <linux/fs.h>
12 #include <linux/types.h>
13 #include <linux/time_types.h>
14 
15 #ifdef __cplusplus
16 extern "C" {
17 #endif
18 
19 /*
20  * IO submission data structure (Submission Queue Entry)
21  */
22 struct io_uring_sqe {
23 	__u8	opcode;		/* type of operation for this sqe */
24 	__u8	flags;		/* IOSQE_ flags */
25 	__u16	ioprio;		/* ioprio for the request */
26 	__s32	fd;		/* file descriptor to do IO on */
27 	union {
28 		__u64	off;	/* offset into file */
29 		__u64	addr2;
30 		struct {
31 			__u32	cmd_op;
32 			__u32	__pad1;
33 		};
34 	};
35 	union {
36 		__u64	addr;	/* pointer to buffer or iovecs */
37 		__u64	splice_off_in;
38 	};
39 	__u32	len;		/* buffer size or number of iovecs */
40 	union {
41 		__kernel_rwf_t	rw_flags;
42 		__u32		fsync_flags;
43 		__u16		poll_events;	/* compatibility */
44 		__u32		poll32_events;	/* word-reversed for BE */
45 		__u32		sync_range_flags;
46 		__u32		msg_flags;
47 		__u32		timeout_flags;
48 		__u32		accept_flags;
49 		__u32		cancel_flags;
50 		__u32		open_flags;
51 		__u32		statx_flags;
52 		__u32		fadvise_advice;
53 		__u32		splice_flags;
54 		__u32		rename_flags;
55 		__u32		unlink_flags;
56 		__u32		hardlink_flags;
57 		__u32		xattr_flags;
58 		__u32		msg_ring_flags;
59 		__u32		uring_cmd_flags;
60 	};
61 	__u64	user_data;	/* data to be passed back at completion time */
62 	/* pack this to avoid bogus arm OABI complaints */
63 	union {
64 		/* index into fixed buffers, if used */
65 		__u16	buf_index;
66 		/* for grouped buffer selection */
67 		__u16	buf_group;
68 	} __attribute__((packed));
69 	/* personality to use, if used */
70 	__u16	personality;
71 	union {
72 		__s32	splice_fd_in;
73 		__u32	file_index;
74 		struct {
75 			__u16	addr_len;
76 			__u16	__pad3[1];
77 		};
78 	};
79 	union {
80 		struct {
81 			__u64	addr3;
82 			__u64	__pad2[1];
83 		};
84 		/*
85 		 * If the ring is initialized with IORING_SETUP_SQE128, then
86 		 * this field is used for 80 bytes of arbitrary command data
87 		 */
88 		__u8	cmd[0];
89 	};
90 };
91 
92 /*
93  * If sqe->file_index is set to this for opcodes that instantiate a new
94  * direct descriptor (like openat/openat2/accept), then io_uring will allocate
95  * an available direct descriptor instead of having the application pass one
96  * in. The picked direct descriptor will be returned in cqe->res, or -ENFILE
97  * if the space is full.
98  */
99 #define IORING_FILE_INDEX_ALLOC		(~0U)
100 
101 enum {
102 	IOSQE_FIXED_FILE_BIT,
103 	IOSQE_IO_DRAIN_BIT,
104 	IOSQE_IO_LINK_BIT,
105 	IOSQE_IO_HARDLINK_BIT,
106 	IOSQE_ASYNC_BIT,
107 	IOSQE_BUFFER_SELECT_BIT,
108 	IOSQE_CQE_SKIP_SUCCESS_BIT,
109 };
110 
111 /*
112  * sqe->flags
113  */
114 /* use fixed fileset */
115 #define IOSQE_FIXED_FILE	(1U << IOSQE_FIXED_FILE_BIT)
116 /* issue after inflight IO */
117 #define IOSQE_IO_DRAIN		(1U << IOSQE_IO_DRAIN_BIT)
118 /* links next sqe */
119 #define IOSQE_IO_LINK		(1U << IOSQE_IO_LINK_BIT)
120 /* like LINK, but stronger */
121 #define IOSQE_IO_HARDLINK	(1U << IOSQE_IO_HARDLINK_BIT)
122 /* always go async */
123 #define IOSQE_ASYNC		(1U << IOSQE_ASYNC_BIT)
124 /* select buffer from sqe->buf_group */
125 #define IOSQE_BUFFER_SELECT	(1U << IOSQE_BUFFER_SELECT_BIT)
126 /* don't post CQE if request succeeded */
127 #define IOSQE_CQE_SKIP_SUCCESS	(1U << IOSQE_CQE_SKIP_SUCCESS_BIT)
128 
129 /*
130  * io_uring_setup() flags
131  */
132 #define IORING_SETUP_IOPOLL	(1U << 0)	/* io_context is polled */
133 #define IORING_SETUP_SQPOLL	(1U << 1)	/* SQ poll thread */
134 #define IORING_SETUP_SQ_AFF	(1U << 2)	/* sq_thread_cpu is valid */
135 #define IORING_SETUP_CQSIZE	(1U << 3)	/* app defines CQ size */
136 #define IORING_SETUP_CLAMP	(1U << 4)	/* clamp SQ/CQ ring sizes */
137 #define IORING_SETUP_ATTACH_WQ	(1U << 5)	/* attach to existing wq */
138 #define IORING_SETUP_R_DISABLED	(1U << 6)	/* start with ring disabled */
139 #define IORING_SETUP_SUBMIT_ALL	(1U << 7)	/* continue submit on error */
140 /*
141  * Cooperative task running. When requests complete, they often require
142  * forcing the submitter to transition to the kernel to complete. If this
143  * flag is set, work will be done when the task transitions anyway, rather
144  * than force an inter-processor interrupt reschedule. This avoids interrupting
145  * a task running in userspace, and saves an IPI.
146  */
147 #define IORING_SETUP_COOP_TASKRUN	(1U << 8)
148 /*
149  * If COOP_TASKRUN is set, get notified if task work is available for
150  * running and a kernel transition would be needed to run it. This sets
151  * IORING_SQ_TASKRUN in the sq ring flags. Not valid with COOP_TASKRUN.
152  */
153 #define IORING_SETUP_TASKRUN_FLAG	(1U << 9)
154 #define IORING_SETUP_SQE128		(1U << 10) /* SQEs are 128 byte */
155 #define IORING_SETUP_CQE32		(1U << 11) /* CQEs are 32 byte */
156 /*
157  * Only one task is allowed to submit requests
158  */
159 #define IORING_SETUP_SINGLE_ISSUER	(1U << 12)
160 
161 /*
162  * Defer running task work to get events.
163  * Rather than running bits of task work whenever the task transitions
164  * try to do it just before it is needed.
165  */
166 #define IORING_SETUP_DEFER_TASKRUN	(1U << 13)
167 
168 enum io_uring_op {
169 	IORING_OP_NOP,
170 	IORING_OP_READV,
171 	IORING_OP_WRITEV,
172 	IORING_OP_FSYNC,
173 	IORING_OP_READ_FIXED,
174 	IORING_OP_WRITE_FIXED,
175 	IORING_OP_POLL_ADD,
176 	IORING_OP_POLL_REMOVE,
177 	IORING_OP_SYNC_FILE_RANGE,
178 	IORING_OP_SENDMSG,
179 	IORING_OP_RECVMSG,
180 	IORING_OP_TIMEOUT,
181 	IORING_OP_TIMEOUT_REMOVE,
182 	IORING_OP_ACCEPT,
183 	IORING_OP_ASYNC_CANCEL,
184 	IORING_OP_LINK_TIMEOUT,
185 	IORING_OP_CONNECT,
186 	IORING_OP_FALLOCATE,
187 	IORING_OP_OPENAT,
188 	IORING_OP_CLOSE,
189 	IORING_OP_FILES_UPDATE,
190 	IORING_OP_STATX,
191 	IORING_OP_READ,
192 	IORING_OP_WRITE,
193 	IORING_OP_FADVISE,
194 	IORING_OP_MADVISE,
195 	IORING_OP_SEND,
196 	IORING_OP_RECV,
197 	IORING_OP_OPENAT2,
198 	IORING_OP_EPOLL_CTL,
199 	IORING_OP_SPLICE,
200 	IORING_OP_PROVIDE_BUFFERS,
201 	IORING_OP_REMOVE_BUFFERS,
202 	IORING_OP_TEE,
203 	IORING_OP_SHUTDOWN,
204 	IORING_OP_RENAMEAT,
205 	IORING_OP_UNLINKAT,
206 	IORING_OP_MKDIRAT,
207 	IORING_OP_SYMLINKAT,
208 	IORING_OP_LINKAT,
209 	IORING_OP_MSG_RING,
210 	IORING_OP_FSETXATTR,
211 	IORING_OP_SETXATTR,
212 	IORING_OP_FGETXATTR,
213 	IORING_OP_GETXATTR,
214 	IORING_OP_SOCKET,
215 	IORING_OP_URING_CMD,
216 	IORING_OP_SEND_ZC,
217 	IORING_OP_SENDMSG_ZC,
218 
219 	/* this goes last, obviously */
220 	IORING_OP_LAST,
221 };
222 
223 /*
224  * sqe->uring_cmd_flags
225  * IORING_URING_CMD_FIXED	use registered buffer; pass this flag
226  *				along with setting sqe->buf_index.
227  */
228 #define IORING_URING_CMD_FIXED	(1U << 0)
229 
230 
231 /*
232  * sqe->fsync_flags
233  */
234 #define IORING_FSYNC_DATASYNC	(1U << 0)
235 
236 /*
237  * sqe->timeout_flags
238  */
239 #define IORING_TIMEOUT_ABS		(1U << 0)
240 #define IORING_TIMEOUT_UPDATE		(1U << 1)
241 #define IORING_TIMEOUT_BOOTTIME		(1U << 2)
242 #define IORING_TIMEOUT_REALTIME		(1U << 3)
243 #define IORING_LINK_TIMEOUT_UPDATE	(1U << 4)
244 #define IORING_TIMEOUT_ETIME_SUCCESS	(1U << 5)
245 #define IORING_TIMEOUT_CLOCK_MASK	(IORING_TIMEOUT_BOOTTIME | IORING_TIMEOUT_REALTIME)
246 #define IORING_TIMEOUT_UPDATE_MASK	(IORING_TIMEOUT_UPDATE | IORING_LINK_TIMEOUT_UPDATE)
247 /*
248  * sqe->splice_flags
249  * extends splice(2) flags
250  */
251 #define SPLICE_F_FD_IN_FIXED	(1U << 31) /* the last bit of __u32 */
252 
253 /*
254  * POLL_ADD flags. Note that since sqe->poll_events is the flag space, the
255  * command flags for POLL_ADD are stored in sqe->len.
256  *
257  * IORING_POLL_ADD_MULTI	Multishot poll. Sets IORING_CQE_F_MORE if
258  *				the poll handler will continue to report
259  *				CQEs on behalf of the same SQE.
260  *
261  * IORING_POLL_UPDATE		Update existing poll request, matching
262  *				sqe->addr as the old user_data field.
263  *
264  * IORING_POLL_LEVEL		Level triggered poll.
265  */
266 #define IORING_POLL_ADD_MULTI	(1U << 0)
267 #define IORING_POLL_UPDATE_EVENTS	(1U << 1)
268 #define IORING_POLL_UPDATE_USER_DATA	(1U << 2)
269 #define IORING_POLL_ADD_LEVEL		(1U << 3)
270 
271 /*
272  * ASYNC_CANCEL flags.
273  *
274  * IORING_ASYNC_CANCEL_ALL	Cancel all requests that match the given key
275  * IORING_ASYNC_CANCEL_FD	Key off 'fd' for cancelation rather than the
276  *				request 'user_data'
277  * IORING_ASYNC_CANCEL_ANY	Match any request
278  * IORING_ASYNC_CANCEL_FD_FIXED	'fd' passed in is a fixed descriptor
279  */
280 #define IORING_ASYNC_CANCEL_ALL	(1U << 0)
281 #define IORING_ASYNC_CANCEL_FD	(1U << 1)
282 #define IORING_ASYNC_CANCEL_ANY	(1U << 2)
283 #define IORING_ASYNC_CANCEL_FD_FIXED	(1U << 3)
284 
285 /*
286  * send/sendmsg and recv/recvmsg flags (sqe->ioprio)
287  *
288  * IORING_RECVSEND_POLL_FIRST	If set, instead of first attempting to send
289  *				or receive and arm poll if that yields an
290  *				-EAGAIN result, arm poll upfront and skip
291  *				the initial transfer attempt.
292  *
293  * IORING_RECV_MULTISHOT	Multishot recv. Sets IORING_CQE_F_MORE if
294  *				the handler will continue to report
295  *				CQEs on behalf of the same SQE.
296  *
297  * IORING_RECVSEND_FIXED_BUF	Use registered buffers, the index is stored in
298  *				the buf_index field.
299  *
300  * IORING_SEND_ZC_REPORT_USAGE
301  *				If set, SEND[MSG]_ZC should report
302  *				the zerocopy usage in cqe.res
303  *				for the IORING_CQE_F_NOTIF cqe.
304  *				0 is reported if zerocopy was actually possible.
305  *				IORING_NOTIF_USAGE_ZC_COPIED if data was copied
306  *				(at least partially).
307  */
308 #define IORING_RECVSEND_POLL_FIRST	(1U << 0)
309 #define IORING_RECV_MULTISHOT		(1U << 1)
310 #define IORING_RECVSEND_FIXED_BUF	(1U << 2)
311 #define IORING_SEND_ZC_REPORT_USAGE	(1U << 3)
312 
313 /*
314  * cqe.res for IORING_CQE_F_NOTIF if
315  * IORING_SEND_ZC_REPORT_USAGE was requested
316  *
317  * It should be treated as a flag, all other
318  * bits of cqe.res should be treated as reserved!
319  */
320 #define IORING_NOTIF_USAGE_ZC_COPIED    (1U << 31)
321 
322 /*
323  * accept flags stored in sqe->ioprio
324  */
325 #define IORING_ACCEPT_MULTISHOT	(1U << 0)
326 
327 /*
328  * IORING_OP_MSG_RING command types, stored in sqe->addr
329  */
330 enum {
331 	IORING_MSG_DATA,	/* pass sqe->len as 'res' and off as user_data */
332 	IORING_MSG_SEND_FD,	/* send a registered fd to another ring */
333 };
334 
335 /*
336  * IORING_OP_MSG_RING flags (sqe->msg_ring_flags)
337  *
338  * IORING_MSG_RING_CQE_SKIP	Don't post a CQE to the target ring. Not
339  *				applicable for IORING_MSG_DATA, obviously.
340  */
341 #define IORING_MSG_RING_CQE_SKIP	(1U << 0)
342 
343 /*
344  * IO completion data structure (Completion Queue Entry)
345  */
346 struct io_uring_cqe {
347 	__u64	user_data;	/* sqe->data submission passed back */
348 	__s32	res;		/* result code for this event */
349 	__u32	flags;
350 
351 	/*
352 	 * If the ring is initialized with IORING_SETUP_CQE32, then this field
353 	 * contains 16-bytes of padding, doubling the size of the CQE.
354 	 */
355 	__u64 big_cqe[];
356 };
357 
358 /*
359  * cqe->flags
360  *
361  * IORING_CQE_F_BUFFER	If set, the upper 16 bits are the buffer ID
362  * IORING_CQE_F_MORE	If set, parent SQE will generate more CQE entries
363  * IORING_CQE_F_SOCK_NONEMPTY	If set, more data to read after socket recv
364  * IORING_CQE_F_NOTIF	Set for notification CQEs. Can be used to distinct
365  * 			them from sends.
366  */
367 #define IORING_CQE_F_BUFFER		(1U << 0)
368 #define IORING_CQE_F_MORE		(1U << 1)
369 #define IORING_CQE_F_SOCK_NONEMPTY	(1U << 2)
370 #define IORING_CQE_F_NOTIF		(1U << 3)
371 
372 enum {
373 	IORING_CQE_BUFFER_SHIFT		= 16,
374 };
375 
376 /*
377  * Magic offsets for the application to mmap the data it needs
378  */
379 #define IORING_OFF_SQ_RING		0ULL
380 #define IORING_OFF_CQ_RING		0x8000000ULL
381 #define IORING_OFF_SQES			0x10000000ULL
382 
383 /*
384  * Filled with the offset for mmap(2)
385  */
386 struct io_sqring_offsets {
387 	__u32 head;
388 	__u32 tail;
389 	__u32 ring_mask;
390 	__u32 ring_entries;
391 	__u32 flags;
392 	__u32 dropped;
393 	__u32 array;
394 	__u32 resv1;
395 	__u64 resv2;
396 };
397 
398 /*
399  * sq_ring->flags
400  */
401 #define IORING_SQ_NEED_WAKEUP	(1U << 0) /* needs io_uring_enter wakeup */
402 #define IORING_SQ_CQ_OVERFLOW	(1U << 1) /* CQ ring is overflown */
403 #define IORING_SQ_TASKRUN	(1U << 2) /* task should enter the kernel */
404 
405 struct io_cqring_offsets {
406 	__u32 head;
407 	__u32 tail;
408 	__u32 ring_mask;
409 	__u32 ring_entries;
410 	__u32 overflow;
411 	__u32 cqes;
412 	__u32 flags;
413 	__u32 resv1;
414 	__u64 resv2;
415 };
416 
417 /*
418  * cq_ring->flags
419  */
420 
421 /* disable eventfd notifications */
422 #define IORING_CQ_EVENTFD_DISABLED	(1U << 0)
423 
424 /*
425  * io_uring_enter(2) flags
426  */
427 #define IORING_ENTER_GETEVENTS		(1U << 0)
428 #define IORING_ENTER_SQ_WAKEUP		(1U << 1)
429 #define IORING_ENTER_SQ_WAIT		(1U << 2)
430 #define IORING_ENTER_EXT_ARG		(1U << 3)
431 #define IORING_ENTER_REGISTERED_RING	(1U << 4)
432 
433 /*
434  * Passed in for io_uring_setup(2). Copied back with updated info on success
435  */
436 struct io_uring_params {
437 	__u32 sq_entries;
438 	__u32 cq_entries;
439 	__u32 flags;
440 	__u32 sq_thread_cpu;
441 	__u32 sq_thread_idle;
442 	__u32 features;
443 	__u32 wq_fd;
444 	__u32 resv[3];
445 	struct io_sqring_offsets sq_off;
446 	struct io_cqring_offsets cq_off;
447 };
448 
449 /*
450  * io_uring_params->features flags
451  */
452 #define IORING_FEAT_SINGLE_MMAP		(1U << 0)
453 #define IORING_FEAT_NODROP		(1U << 1)
454 #define IORING_FEAT_SUBMIT_STABLE	(1U << 2)
455 #define IORING_FEAT_RW_CUR_POS		(1U << 3)
456 #define IORING_FEAT_CUR_PERSONALITY	(1U << 4)
457 #define IORING_FEAT_FAST_POLL		(1U << 5)
458 #define IORING_FEAT_POLL_32BITS 	(1U << 6)
459 #define IORING_FEAT_SQPOLL_NONFIXED	(1U << 7)
460 #define IORING_FEAT_EXT_ARG		(1U << 8)
461 #define IORING_FEAT_NATIVE_WORKERS	(1U << 9)
462 #define IORING_FEAT_RSRC_TAGS		(1U << 10)
463 #define IORING_FEAT_CQE_SKIP		(1U << 11)
464 #define IORING_FEAT_LINKED_FILE		(1U << 12)
465 
466 /*
467  * io_uring_register(2) opcodes and arguments
468  */
469 enum {
470 	IORING_REGISTER_BUFFERS			= 0,
471 	IORING_UNREGISTER_BUFFERS		= 1,
472 	IORING_REGISTER_FILES			= 2,
473 	IORING_UNREGISTER_FILES			= 3,
474 	IORING_REGISTER_EVENTFD			= 4,
475 	IORING_UNREGISTER_EVENTFD		= 5,
476 	IORING_REGISTER_FILES_UPDATE		= 6,
477 	IORING_REGISTER_EVENTFD_ASYNC		= 7,
478 	IORING_REGISTER_PROBE			= 8,
479 	IORING_REGISTER_PERSONALITY		= 9,
480 	IORING_UNREGISTER_PERSONALITY		= 10,
481 	IORING_REGISTER_RESTRICTIONS		= 11,
482 	IORING_REGISTER_ENABLE_RINGS		= 12,
483 
484 	/* extended with tagging */
485 	IORING_REGISTER_FILES2			= 13,
486 	IORING_REGISTER_FILES_UPDATE2		= 14,
487 	IORING_REGISTER_BUFFERS2		= 15,
488 	IORING_REGISTER_BUFFERS_UPDATE		= 16,
489 
490 	/* set/clear io-wq thread affinities */
491 	IORING_REGISTER_IOWQ_AFF		= 17,
492 	IORING_UNREGISTER_IOWQ_AFF		= 18,
493 
494 	/* set/get max number of io-wq workers */
495 	IORING_REGISTER_IOWQ_MAX_WORKERS	= 19,
496 
497 	/* register/unregister io_uring fd with the ring */
498 	IORING_REGISTER_RING_FDS		= 20,
499 	IORING_UNREGISTER_RING_FDS		= 21,
500 
501 	/* register ring based provide buffer group */
502 	IORING_REGISTER_PBUF_RING		= 22,
503 	IORING_UNREGISTER_PBUF_RING		= 23,
504 
505 	/* sync cancelation API */
506 	IORING_REGISTER_SYNC_CANCEL		= 24,
507 
508 	/* register a range of fixed file slots for automatic slot allocation */
509 	IORING_REGISTER_FILE_ALLOC_RANGE	= 25,
510 
511 	/* this goes last */
512 	IORING_REGISTER_LAST
513 };
514 
515 /* io-wq worker categories */
516 enum {
517 	IO_WQ_BOUND,
518 	IO_WQ_UNBOUND,
519 };
520 
521 /* deprecated, see struct io_uring_rsrc_update */
522 struct io_uring_files_update {
523 	__u32 offset;
524 	__u32 resv;
525 	__aligned_u64 /* __s32 * */ fds;
526 };
527 
528 /*
529  * Register a fully sparse file space, rather than pass in an array of all
530  * -1 file descriptors.
531  */
532 #define IORING_RSRC_REGISTER_SPARSE	(1U << 0)
533 
534 struct io_uring_rsrc_register {
535 	__u32 nr;
536 	__u32 flags;
537 	__u64 resv2;
538 	__aligned_u64 data;
539 	__aligned_u64 tags;
540 };
541 
542 struct io_uring_rsrc_update {
543 	__u32 offset;
544 	__u32 resv;
545 	__aligned_u64 data;
546 };
547 
548 struct io_uring_rsrc_update2 {
549 	__u32 offset;
550 	__u32 resv;
551 	__aligned_u64 data;
552 	__aligned_u64 tags;
553 	__u32 nr;
554 	__u32 resv2;
555 };
556 
557 struct io_uring_notification_slot {
558 	__u64 tag;
559 	__u64 resv[3];
560 };
561 
562 struct io_uring_notification_register {
563 	__u32 nr_slots;
564 	__u32 resv;
565 	__u64 resv2;
566 	__u64 data;
567 	__u64 resv3;
568 };
569 
570 /* Skip updating fd indexes set to this value in the fd table */
571 #define IORING_REGISTER_FILES_SKIP	(-2)
572 
573 #define IO_URING_OP_SUPPORTED	(1U << 0)
574 
575 struct io_uring_probe_op {
576 	__u8 op;
577 	__u8 resv;
578 	__u16 flags;	/* IO_URING_OP_* flags */
579 	__u32 resv2;
580 };
581 
582 struct io_uring_probe {
583 	__u8 last_op;	/* last opcode supported */
584 	__u8 ops_len;	/* length of ops[] array below */
585 	__u16 resv;
586 	__u32 resv2[3];
587 	struct io_uring_probe_op ops[];
588 };
589 
590 struct io_uring_restriction {
591 	__u16 opcode;
592 	union {
593 		__u8 register_op; /* IORING_RESTRICTION_REGISTER_OP */
594 		__u8 sqe_op;      /* IORING_RESTRICTION_SQE_OP */
595 		__u8 sqe_flags;   /* IORING_RESTRICTION_SQE_FLAGS_* */
596 	};
597 	__u8 resv;
598 	__u32 resv2[3];
599 };
600 
601 struct io_uring_buf {
602 	__u64	addr;
603 	__u32	len;
604 	__u16	bid;
605 	__u16	resv;
606 };
607 
608 struct io_uring_buf_ring {
609 	union {
610 		/*
611 		 * To avoid spilling into more pages than we need to, the
612 		 * ring tail is overlaid with the io_uring_buf->resv field.
613 		 */
614 		struct {
615 			__u64	resv1;
616 			__u32	resv2;
617 			__u16	resv3;
618 			__u16	tail;
619 		};
620 		struct io_uring_buf	bufs[0];
621 	};
622 };
623 
624 /* argument for IORING_(UN)REGISTER_PBUF_RING */
625 struct io_uring_buf_reg {
626 	__u64	ring_addr;
627 	__u32	ring_entries;
628 	__u16	bgid;
629 	__u16	pad;
630 	__u64	resv[3];
631 };
632 
633 /*
634  * io_uring_restriction->opcode values
635  */
636 enum {
637 	/* Allow an io_uring_register(2) opcode */
638 	IORING_RESTRICTION_REGISTER_OP		= 0,
639 
640 	/* Allow an sqe opcode */
641 	IORING_RESTRICTION_SQE_OP		= 1,
642 
643 	/* Allow sqe flags */
644 	IORING_RESTRICTION_SQE_FLAGS_ALLOWED	= 2,
645 
646 	/* Require sqe flags (these flags must be set on each submission) */
647 	IORING_RESTRICTION_SQE_FLAGS_REQUIRED	= 3,
648 
649 	IORING_RESTRICTION_LAST
650 };
651 
652 struct io_uring_getevents_arg {
653 	__u64	sigmask;
654 	__u32	sigmask_sz;
655 	__u32	pad;
656 	__u64	ts;
657 };
658 
659 /*
660  * Argument for IORING_REGISTER_SYNC_CANCEL
661  */
662 struct io_uring_sync_cancel_reg {
663 	__u64				addr;
664 	__s32				fd;
665 	__u32				flags;
666 	struct __kernel_timespec	timeout;
667 	__u64				pad[4];
668 };
669 
670 /*
671  * Argument for IORING_REGISTER_FILE_ALLOC_RANGE
672  * The range is specified as [off, off + len)
673  */
674 struct io_uring_file_index_range {
675 	__u32	off;
676 	__u32	len;
677 	__u64	resv;
678 };
679 
680 struct io_uring_recvmsg_out {
681 	__u32 namelen;
682 	__u32 controllen;
683 	__u32 payloadlen;
684 	__u32 flags;
685 };
686 
687 #ifdef __cplusplus
688 }
689 #endif
690 
691 #endif
692