io_uring.c 70.0 KB
Newer Older
J
Jens Axboe 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
// SPDX-License-Identifier: GPL-2.0
/*
 * Shared application/kernel submission and completion ring pairs, for
 * supporting fast/efficient IO.
 *
 * A note on the read/write ordering memory barriers that are matched between
 * the application and kernel side. When the application reads the CQ ring
 * tail, it must use an appropriate smp_rmb() to order with the smp_wmb()
 * the kernel uses after writing the tail. Failure to do so could cause a
 * delay in when the application notices that completion events available.
 * This isn't a fatal condition. Likewise, the application must use an
 * appropriate smp_wmb() both before writing the SQ tail, and after writing
 * the SQ tail. The first one orders the sqe writes with the tail write, and
 * the latter is paired with the smp_rmb() the kernel will issue before
 * reading the SQ tail on submission.
 *
 * Also see the examples in the liburing library:
 *
 *	git://git.kernel.dk/liburing
 *
 * io_uring also uses READ/WRITE_ONCE() for _any_ store or load that happens
 * from data shared between the kernel and application. This is done both
 * for ordering purposes, but also to ensure that once a value is loaded from
 * data that the application could potentially modify, it remains stable.
 *
 * Copyright (C) 2018-2019 Jens Axboe
C
Christoph Hellwig 已提交
27
 * Copyright (c) 2018-2019 Christoph Hellwig
J
Jens Axboe 已提交
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/syscalls.h>
#include <linux/compat.h>
#include <linux/refcount.h>
#include <linux/uio.h>

#include <linux/sched/signal.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/mmu_context.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
J
Jens Axboe 已提交
47
#include <linux/kthread.h>
J
Jens Axboe 已提交
48
#include <linux/blkdev.h>
49
#include <linux/bvec.h>
J
Jens Axboe 已提交
50 51 52
#include <linux/net.h>
#include <net/sock.h>
#include <net/af_unix.h>
J
Jens Axboe 已提交
53
#include <net/scm.h>
J
Jens Axboe 已提交
54 55 56 57
#include <linux/anon_inodes.h>
#include <linux/sched/mm.h>
#include <linux/uaccess.h>
#include <linux/nospec.h>
58 59
#include <linux/sizes.h>
#include <linux/hugetlb.h>
J
Jens Axboe 已提交
60 61 62 63 64 65

#include <uapi/linux/io_uring.h>

#include "internal.h"

#define IORING_MAX_ENTRIES	4096
J
Jens Axboe 已提交
66
#define IORING_MAX_FIXED_FILES	1024
J
Jens Axboe 已提交
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89

struct io_uring {
	u32 head ____cacheline_aligned_in_smp;
	u32 tail ____cacheline_aligned_in_smp;
};

struct io_sq_ring {
	struct io_uring		r;
	u32			ring_mask;
	u32			ring_entries;
	u32			dropped;
	u32			flags;
	u32			array[];
};

struct io_cq_ring {
	struct io_uring		r;
	u32			ring_mask;
	u32			ring_entries;
	u32			overflow;
	struct io_uring_cqe	cqes[];
};

90 91 92 93 94 95 96
struct io_mapped_ubuf {
	u64		ubuf;
	size_t		len;
	struct		bio_vec *bvec;
	unsigned int	nr_bvecs;
};

97 98 99 100 101 102 103 104 105 106
struct async_list {
	spinlock_t		lock;
	atomic_t		cnt;
	struct list_head	list;

	struct file		*file;
	off_t			io_end;
	size_t			io_pages;
};

J
Jens Axboe 已提交
107 108 109 110 111 112 113 114 115 116 117 118 119 120 121
struct io_ring_ctx {
	struct {
		struct percpu_ref	refs;
	} ____cacheline_aligned_in_smp;

	struct {
		unsigned int		flags;
		bool			compat;
		bool			account_mem;

		/* SQ ring */
		struct io_sq_ring	*sq_ring;
		unsigned		cached_sq_head;
		unsigned		sq_entries;
		unsigned		sq_mask;
J
Jens Axboe 已提交
122
		unsigned		sq_thread_idle;
J
Jens Axboe 已提交
123 124 125 126 127
		struct io_uring_sqe	*sq_sqes;
	} ____cacheline_aligned_in_smp;

	/* IO offload */
	struct workqueue_struct	*sqo_wq;
J
Jens Axboe 已提交
128
	struct task_struct	*sqo_thread;	/* if using sq thread polling */
J
Jens Axboe 已提交
129
	struct mm_struct	*sqo_mm;
J
Jens Axboe 已提交
130 131
	wait_queue_head_t	sqo_wait;
	unsigned		sqo_stop;
J
Jens Axboe 已提交
132 133 134 135 136 137 138 139 140 141 142

	struct {
		/* CQ ring */
		struct io_cq_ring	*cq_ring;
		unsigned		cached_cq_tail;
		unsigned		cq_entries;
		unsigned		cq_mask;
		struct wait_queue_head	cq_wait;
		struct fasync_struct	*cq_fasync;
	} ____cacheline_aligned_in_smp;

J
Jens Axboe 已提交
143 144 145 146 147 148 149 150
	/*
	 * If used, fixed file set. Writers must ensure that ->refs is dead,
	 * readers must ensure that ->refs is alive as long as the file* is
	 * used. Only updated through io_uring_register(2).
	 */
	struct file		**user_files;
	unsigned		nr_user_files;

151 152 153 154
	/* if used, fixed mapped user buffers */
	unsigned		nr_user_bufs;
	struct io_mapped_ubuf	*user_bufs;

J
Jens Axboe 已提交
155 156 157 158 159 160 161 162 163 164 165
	struct user_struct	*user;

	struct completion	ctx_done;

	struct {
		struct mutex		uring_lock;
		wait_queue_head_t	wait;
	} ____cacheline_aligned_in_smp;

	struct {
		spinlock_t		completion_lock;
J
Jens Axboe 已提交
166 167 168 169 170 171 172 173
		bool			poll_multi_file;
		/*
		 * ->poll_list is protected by the ctx->uring_lock for
		 * io_uring instances that don't use IORING_SETUP_SQPOLL.
		 * For SQPOLL, only the single threaded io_sq_thread() will
		 * manipulate the list, hence no extra locking is needed there.
		 */
		struct list_head	poll_list;
174
		struct list_head	cancel_list;
J
Jens Axboe 已提交
175 176
	} ____cacheline_aligned_in_smp;

177 178
	struct async_list	pending_async[2];

J
Jens Axboe 已提交
179 180 181 182 183 184 185 186 187
#if defined(CONFIG_UNIX)
	struct socket		*ring_sock;
#endif
};

struct sqe_submit {
	const struct io_uring_sqe	*sqe;
	unsigned short			index;
	bool				has_user;
J
Jens Axboe 已提交
188
	bool				needs_lock;
J
Jens Axboe 已提交
189
	bool				needs_fixed_file;
J
Jens Axboe 已提交
190 191
};

J
Jens Axboe 已提交
192 193 194 195
/*
 * First field must be the file pointer in all the
 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
 */
196 197 198 199
struct io_poll_iocb {
	struct file			*file;
	struct wait_queue_head		*head;
	__poll_t			events;
J
Jens Axboe 已提交
200
	bool				done;
201 202 203 204
	bool				canceled;
	struct wait_queue_entry		wait;
};

J
Jens Axboe 已提交
205 206 207 208 209 210
/*
 * NOTE! Each of the iocb union members has the file pointer
 * as the first entry in their struct definition. So you can
 * access the file pointer through any of the sub-structs,
 * or directly as just 'ki_filp' in this struct.
 */
J
Jens Axboe 已提交
211
struct io_kiocb {
212
	union {
J
Jens Axboe 已提交
213
		struct file		*file;
214 215 216
		struct kiocb		rw;
		struct io_poll_iocb	poll;
	};
J
Jens Axboe 已提交
217 218 219 220 221 222

	struct sqe_submit	submit;

	struct io_ring_ctx	*ctx;
	struct list_head	list;
	unsigned int		flags;
J
Jens Axboe 已提交
223
	refcount_t		refs;
224
#define REQ_F_NOWAIT		1	/* must not punt to workers */
J
Jens Axboe 已提交
225
#define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
J
Jens Axboe 已提交
226
#define REQ_F_FIXED_FILE	4	/* ctx owns file */
227
#define REQ_F_SEQ_PREV		8	/* sequential with previous */
J
Jens Axboe 已提交
228
#define REQ_F_PREPPED		16	/* prep already done */
J
Jens Axboe 已提交
229
	u64			user_data;
J
Jens Axboe 已提交
230
	u64			error;
J
Jens Axboe 已提交
231 232 233 234 235

	struct work_struct	work;
};

#define IO_PLUG_THRESHOLD		2
J
Jens Axboe 已提交
236
#define IO_IOPOLL_BATCH			8
J
Jens Axboe 已提交
237

238 239 240
struct io_submit_state {
	struct blk_plug		plug;

J
Jens Axboe 已提交
241 242 243 244 245 246 247
	/*
	 * io_kiocb alloc cache
	 */
	void			*reqs[IO_IOPOLL_BATCH];
	unsigned		int free_reqs;
	unsigned		int cur_req;

248 249 250 251 252 253 254 255 256 257
	/*
	 * File reference cache
	 */
	struct file		*file;
	unsigned int		fd;
	unsigned int		has_refs;
	unsigned int		used_refs;
	unsigned int		ios_left;
};

J
Jens Axboe 已提交
258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284
static struct kmem_cache *req_cachep;

static const struct file_operations io_uring_fops;

struct sock *io_uring_get_socket(struct file *file)
{
#if defined(CONFIG_UNIX)
	if (file->f_op == &io_uring_fops) {
		struct io_ring_ctx *ctx = file->private_data;

		return ctx->ring_sock->sk;
	}
#endif
	return NULL;
}
EXPORT_SYMBOL(io_uring_get_socket);

static void io_ring_ctx_ref_free(struct percpu_ref *ref)
{
	struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);

	complete(&ctx->ctx_done);
}

static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
{
	struct io_ring_ctx *ctx;
285
	int i;
J
Jens Axboe 已提交
286 287 288 289 290 291 292 293 294 295 296 297 298 299 300

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
		return NULL;

	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free, 0, GFP_KERNEL)) {
		kfree(ctx);
		return NULL;
	}

	ctx->flags = p->flags;
	init_waitqueue_head(&ctx->cq_wait);
	init_completion(&ctx->ctx_done);
	mutex_init(&ctx->uring_lock);
	init_waitqueue_head(&ctx->wait);
301 302 303 304 305
	for (i = 0; i < ARRAY_SIZE(ctx->pending_async); i++) {
		spin_lock_init(&ctx->pending_async[i].lock);
		INIT_LIST_HEAD(&ctx->pending_async[i].list);
		atomic_set(&ctx->pending_async[i].cnt, 0);
	}
J
Jens Axboe 已提交
306
	spin_lock_init(&ctx->completion_lock);
J
Jens Axboe 已提交
307
	INIT_LIST_HEAD(&ctx->poll_list);
308
	INIT_LIST_HEAD(&ctx->cancel_list);
J
Jens Axboe 已提交
309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340
	return ctx;
}

static void io_commit_cqring(struct io_ring_ctx *ctx)
{
	struct io_cq_ring *ring = ctx->cq_ring;

	if (ctx->cached_cq_tail != READ_ONCE(ring->r.tail)) {
		/* order cqe stores with ring update */
		smp_store_release(&ring->r.tail, ctx->cached_cq_tail);

		/*
		 * Write sider barrier of tail update, app has read side. See
		 * comment at the top of this file.
		 */
		smp_wmb();

		if (wq_has_sleeper(&ctx->cq_wait)) {
			wake_up_interruptible(&ctx->cq_wait);
			kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
		}
	}
}

static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
{
	struct io_cq_ring *ring = ctx->cq_ring;
	unsigned tail;

	tail = ctx->cached_cq_tail;
	/* See comment at the top of the file */
	smp_rmb();
J
Jens Axboe 已提交
341
	if (tail - READ_ONCE(ring->r.head) == ring->ring_entries)
J
Jens Axboe 已提交
342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369
		return NULL;

	ctx->cached_cq_tail++;
	return &ring->cqes[tail & ctx->cq_mask];
}

static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
				 long res, unsigned ev_flags)
{
	struct io_uring_cqe *cqe;

	/*
	 * If we can't get a cq entry, userspace overflowed the
	 * submission (by quite a lot). Increment the overflow count in
	 * the ring.
	 */
	cqe = io_get_cqring(ctx);
	if (cqe) {
		WRITE_ONCE(cqe->user_data, ki_user_data);
		WRITE_ONCE(cqe->res, res);
		WRITE_ONCE(cqe->flags, ev_flags);
	} else {
		unsigned overflow = READ_ONCE(ctx->cq_ring->overflow);

		WRITE_ONCE(ctx->cq_ring->overflow, overflow + 1);
	}
}

J
Jens Axboe 已提交
370 371 372 373 374 375 376 377 378
static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
{
	if (waitqueue_active(&ctx->wait))
		wake_up(&ctx->wait);
	if (waitqueue_active(&ctx->sqo_wait))
		wake_up(&ctx->sqo_wait);
}

static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
J
Jens Axboe 已提交
379 380 381 382 383
				long res, unsigned ev_flags)
{
	unsigned long flags;

	spin_lock_irqsave(&ctx->completion_lock, flags);
J
Jens Axboe 已提交
384
	io_cqring_fill_event(ctx, user_data, res, ev_flags);
J
Jens Axboe 已提交
385 386 387
	io_commit_cqring(ctx);
	spin_unlock_irqrestore(&ctx->completion_lock, flags);

J
Jens Axboe 已提交
388
	io_cqring_ev_posted(ctx);
J
Jens Axboe 已提交
389 390 391 392 393 394 395 396 397 398
}

static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
{
	percpu_ref_put_many(&ctx->refs, refs);

	if (waitqueue_active(&ctx->wait))
		wake_up(&ctx->wait);
}

J
Jens Axboe 已提交
399 400
static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
				   struct io_submit_state *state)
J
Jens Axboe 已提交
401
{
402
	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
J
Jens Axboe 已提交
403 404 405 406 407
	struct io_kiocb *req;

	if (!percpu_ref_tryget(&ctx->refs))
		return NULL;

J
Jens Axboe 已提交
408
	if (!state) {
409
		req = kmem_cache_alloc(req_cachep, gfp);
J
Jens Axboe 已提交
410 411 412 413 414 415 416
		if (unlikely(!req))
			goto out;
	} else if (!state->free_reqs) {
		size_t sz;
		int ret;

		sz = min_t(size_t, state->ios_left, ARRAY_SIZE(state->reqs));
417 418 419 420 421 422 423 424 425 426 427 428
		ret = kmem_cache_alloc_bulk(req_cachep, gfp, sz, state->reqs);

		/*
		 * Bulk alloc is all-or-nothing. If we fail to get a batch,
		 * retry single alloc to be on the safe side.
		 */
		if (unlikely(ret <= 0)) {
			state->reqs[0] = kmem_cache_alloc(req_cachep, gfp);
			if (!state->reqs[0])
				goto out;
			ret = 1;
		}
J
Jens Axboe 已提交
429 430 431 432 433 434 435
		state->free_reqs = ret - 1;
		state->cur_req = 1;
		req = state->reqs[0];
	} else {
		req = state->reqs[state->cur_req];
		state->free_reqs--;
		state->cur_req++;
J
Jens Axboe 已提交
436 437
	}

J
Jens Axboe 已提交
438 439
	req->ctx = ctx;
	req->flags = 0;
440 441
	/* one is dropped after submission, the other at completion */
	refcount_set(&req->refs, 2);
J
Jens Axboe 已提交
442 443
	return req;
out:
J
Jens Axboe 已提交
444 445 446 447
	io_ring_drop_ctx_refs(ctx, 1);
	return NULL;
}

J
Jens Axboe 已提交
448 449 450 451 452 453 454 455 456
static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
{
	if (*nr) {
		kmem_cache_free_bulk(req_cachep, *nr, reqs);
		io_ring_drop_ctx_refs(ctx, *nr);
		*nr = 0;
	}
}

J
Jens Axboe 已提交
457 458
static void io_free_req(struct io_kiocb *req)
{
J
Jens Axboe 已提交
459 460
	if (req->file && !(req->flags & REQ_F_FIXED_FILE))
		fput(req->file);
461 462 463 464 465 466 467 468
	io_ring_drop_ctx_refs(req->ctx, 1);
	kmem_cache_free(req_cachep, req);
}

static void io_put_req(struct io_kiocb *req)
{
	if (refcount_dec_and_test(&req->refs))
		io_free_req(req);
J
Jens Axboe 已提交
469 470
}

J
Jens Axboe 已提交
471 472 473 474 475 476 477 478
/*
 * Find and free completed poll iocbs
 */
static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
			       struct list_head *done)
{
	void *reqs[IO_IOPOLL_BATCH];
	struct io_kiocb *req;
J
Jens Axboe 已提交
479
	int to_free;
J
Jens Axboe 已提交
480

J
Jens Axboe 已提交
481
	to_free = 0;
J
Jens Axboe 已提交
482 483 484 485 486 487 488
	while (!list_empty(done)) {
		req = list_first_entry(done, struct io_kiocb, list);
		list_del(&req->list);

		io_cqring_fill_event(ctx, req->user_data, req->error, 0);
		(*nr_events)++;

J
Jens Axboe 已提交
489 490 491 492 493 494 495 496 497 498
		if (refcount_dec_and_test(&req->refs)) {
			/* If we're not using fixed files, we have to pair the
			 * completion part with the file put. Use regular
			 * completions for those, only batch free for fixed
			 * file.
			 */
			if (req->flags & REQ_F_FIXED_FILE) {
				reqs[to_free++] = req;
				if (to_free == ARRAY_SIZE(reqs))
					io_free_req_many(ctx, reqs, &to_free);
J
Jens Axboe 已提交
499
			} else {
J
Jens Axboe 已提交
500
				io_free_req(req);
J
Jens Axboe 已提交
501
			}
502
		}
J
Jens Axboe 已提交
503 504
	}

J
Jens Axboe 已提交
505
	io_commit_cqring(ctx);
J
Jens Axboe 已提交
506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612
	io_free_req_many(ctx, reqs, &to_free);
}

static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
			long min)
{
	struct io_kiocb *req, *tmp;
	LIST_HEAD(done);
	bool spin;
	int ret;

	/*
	 * Only spin for completions if we don't have multiple devices hanging
	 * off our complete list, and we're under the requested amount.
	 */
	spin = !ctx->poll_multi_file && *nr_events < min;

	ret = 0;
	list_for_each_entry_safe(req, tmp, &ctx->poll_list, list) {
		struct kiocb *kiocb = &req->rw;

		/*
		 * Move completed entries to our local list. If we find a
		 * request that requires polling, break out and complete
		 * the done list first, if we have entries there.
		 */
		if (req->flags & REQ_F_IOPOLL_COMPLETED) {
			list_move_tail(&req->list, &done);
			continue;
		}
		if (!list_empty(&done))
			break;

		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
		if (ret < 0)
			break;

		if (ret && spin)
			spin = false;
		ret = 0;
	}

	if (!list_empty(&done))
		io_iopoll_complete(ctx, nr_events, &done);

	return ret;
}

/*
 * Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
 * non-spinning poll check - we'll still enter the driver poll loop, but only
 * as a non-spinning completion check.
 */
static int io_iopoll_getevents(struct io_ring_ctx *ctx, unsigned int *nr_events,
				long min)
{
	while (!list_empty(&ctx->poll_list)) {
		int ret;

		ret = io_do_iopoll(ctx, nr_events, min);
		if (ret < 0)
			return ret;
		if (!min || *nr_events >= min)
			return 0;
	}

	return 1;
}

/*
 * We can't just wait for polled events to come to us, we have to actively
 * find and complete them.
 */
static void io_iopoll_reap_events(struct io_ring_ctx *ctx)
{
	if (!(ctx->flags & IORING_SETUP_IOPOLL))
		return;

	mutex_lock(&ctx->uring_lock);
	while (!list_empty(&ctx->poll_list)) {
		unsigned int nr_events = 0;

		io_iopoll_getevents(ctx, &nr_events, 1);
	}
	mutex_unlock(&ctx->uring_lock);
}

static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
			   long min)
{
	int ret = 0;

	do {
		int tmin = 0;

		if (*nr_events < min)
			tmin = min - *nr_events;

		ret = io_iopoll_getevents(ctx, nr_events, tmin);
		if (ret <= 0)
			break;
		ret = 0;
	} while (min && !*nr_events && !need_resched());

	return ret;
}

J
Jens Axboe 已提交
613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634
static void kiocb_end_write(struct kiocb *kiocb)
{
	if (kiocb->ki_flags & IOCB_WRITE) {
		struct inode *inode = file_inode(kiocb->ki_filp);

		/*
		 * Tell lockdep we inherited freeze protection from submission
		 * thread.
		 */
		if (S_ISREG(inode->i_mode))
			__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
		file_end_write(kiocb->ki_filp);
	}
}

static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
{
	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);

	kiocb_end_write(kiocb);

	io_cqring_add_event(req->ctx, req->user_data, res, 0);
635
	io_put_req(req);
J
Jens Axboe 已提交
636 637
}

J
Jens Axboe 已提交
638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684
static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
{
	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);

	kiocb_end_write(kiocb);

	req->error = res;
	if (res != -EAGAIN)
		req->flags |= REQ_F_IOPOLL_COMPLETED;
}

/*
 * After the iocb has been issued, it's safe to be found on the poll list.
 * Adding the kiocb to the list AFTER submission ensures that we don't
 * find it from a io_iopoll_getevents() thread before the issuer is done
 * accessing the kiocb cookie.
 */
static void io_iopoll_req_issued(struct io_kiocb *req)
{
	struct io_ring_ctx *ctx = req->ctx;

	/*
	 * Track whether we have multiple files in our lists. This will impact
	 * how we do polling eventually, not spinning if we're on potentially
	 * different devices.
	 */
	if (list_empty(&ctx->poll_list)) {
		ctx->poll_multi_file = false;
	} else if (!ctx->poll_multi_file) {
		struct io_kiocb *list_req;

		list_req = list_first_entry(&ctx->poll_list, struct io_kiocb,
						list);
		if (list_req->rw.ki_filp != req->rw.ki_filp)
			ctx->poll_multi_file = true;
	}

	/*
	 * For fast devices, IO may have already completed. If it has, add
	 * it to the front so we find it first.
	 */
	if (req->flags & REQ_F_IOPOLL_COMPLETED)
		list_add(&req->list, &ctx->poll_list);
	else
		list_add_tail(&req->list, &ctx->poll_list);
}

685
static void io_file_put(struct io_submit_state *state)
686
{
687
	if (state->file) {
688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711
		int diff = state->has_refs - state->used_refs;

		if (diff)
			fput_many(state->file, diff);
		state->file = NULL;
	}
}

/*
 * Get as many references to a file as we have IOs left in this submission,
 * assuming most submissions are for one file, or at least that each file
 * has more than one submission.
 */
static struct file *io_file_get(struct io_submit_state *state, int fd)
{
	if (!state)
		return fget(fd);

	if (state->file) {
		if (state->fd == fd) {
			state->used_refs++;
			state->ios_left--;
			return state->file;
		}
712
		io_file_put(state);
713 714 715 716 717 718 719 720 721 722 723 724
	}
	state->file = fget_many(fd, state->ios_left);
	if (!state->file)
		return NULL;

	state->fd = fd;
	state->has_refs = state->ios_left;
	state->used_refs = 1;
	state->ios_left--;
	return state->file;
}

J
Jens Axboe 已提交
725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741
/*
 * If we tracked the file through the SCM inflight mechanism, we could support
 * any file. For now, just ensure that anything potentially problematic is done
 * inline.
 */
static bool io_file_supports_async(struct file *file)
{
	umode_t mode = file_inode(file)->i_mode;

	if (S_ISBLK(mode) || S_ISCHR(mode))
		return true;
	if (S_ISREG(mode) && file->f_op != &io_uring_fops)
		return true;

	return false;
}

J
Jens Axboe 已提交
742
static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
743
		      bool force_nonblock)
J
Jens Axboe 已提交
744
{
J
Jens Axboe 已提交
745
	const struct io_uring_sqe *sqe = s->sqe;
J
Jens Axboe 已提交
746
	struct io_ring_ctx *ctx = req->ctx;
J
Jens Axboe 已提交
747
	struct kiocb *kiocb = &req->rw;
J
Jens Axboe 已提交
748 749
	unsigned ioprio;
	int ret;
J
Jens Axboe 已提交
750

J
Jens Axboe 已提交
751 752
	if (!req->file)
		return -EBADF;
J
Jens Axboe 已提交
753
	/* For -EAGAIN retry, everything is already prepped */
J
Jens Axboe 已提交
754
	if (req->flags & REQ_F_PREPPED)
J
Jens Axboe 已提交
755 756
		return 0;

J
Jens Axboe 已提交
757 758
	if (force_nonblock && !io_file_supports_async(req->file))
		force_nonblock = false;
J
Jens Axboe 已提交
759

J
Jens Axboe 已提交
760 761 762 763 764 765 766 767
	kiocb->ki_pos = READ_ONCE(sqe->off);
	kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
	kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));

	ioprio = READ_ONCE(sqe->ioprio);
	if (ioprio) {
		ret = ioprio_check_cap(ioprio);
		if (ret)
J
Jens Axboe 已提交
768
			return ret;
J
Jens Axboe 已提交
769 770 771 772 773 774 775

		kiocb->ki_ioprio = ioprio;
	} else
		kiocb->ki_ioprio = get_current_ioprio();

	ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
	if (unlikely(ret))
J
Jens Axboe 已提交
776
		return ret;
777 778 779 780 781 782

	/* don't allow async punt if RWF_NOWAIT was requested */
	if (kiocb->ki_flags & IOCB_NOWAIT)
		req->flags |= REQ_F_NOWAIT;

	if (force_nonblock)
J
Jens Axboe 已提交
783
		kiocb->ki_flags |= IOCB_NOWAIT;
784

J
Jens Axboe 已提交
785 786 787
	if (ctx->flags & IORING_SETUP_IOPOLL) {
		if (!(kiocb->ki_flags & IOCB_DIRECT) ||
		    !kiocb->ki_filp->f_op->iopoll)
J
Jens Axboe 已提交
788
			return -EOPNOTSUPP;
J
Jens Axboe 已提交
789

J
Jens Axboe 已提交
790 791 792 793
		req->error = 0;
		kiocb->ki_flags |= IOCB_HIPRI;
		kiocb->ki_complete = io_complete_rw_iopoll;
	} else {
J
Jens Axboe 已提交
794 795
		if (kiocb->ki_flags & IOCB_HIPRI)
			return -EINVAL;
J
Jens Axboe 已提交
796 797
		kiocb->ki_complete = io_complete_rw;
	}
J
Jens Axboe 已提交
798
	req->flags |= REQ_F_PREPPED;
J
Jens Axboe 已提交
799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822
	return 0;
}

static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
{
	switch (ret) {
	case -EIOCBQUEUED:
		break;
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	case -ERESTARTNOHAND:
	case -ERESTART_RESTARTBLOCK:
		/*
		 * We can't just restart the syscall, since previously
		 * submitted sqes may already be in progress. Just fail this
		 * IO with EINTR.
		 */
		ret = -EINTR;
		/* fall through */
	default:
		kiocb->ki_complete(kiocb, ret, 0);
	}
}

823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859
static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
			   const struct io_uring_sqe *sqe,
			   struct iov_iter *iter)
{
	size_t len = READ_ONCE(sqe->len);
	struct io_mapped_ubuf *imu;
	unsigned index, buf_index;
	size_t offset;
	u64 buf_addr;

	/* attempt to use fixed buffers without having provided iovecs */
	if (unlikely(!ctx->user_bufs))
		return -EFAULT;

	buf_index = READ_ONCE(sqe->buf_index);
	if (unlikely(buf_index >= ctx->nr_user_bufs))
		return -EFAULT;

	index = array_index_nospec(buf_index, ctx->nr_user_bufs);
	imu = &ctx->user_bufs[index];
	buf_addr = READ_ONCE(sqe->addr);

	/* overflow */
	if (buf_addr + len < buf_addr)
		return -EFAULT;
	/* not inside the mapped region */
	if (buf_addr < imu->ubuf || buf_addr + len > imu->ubuf + imu->len)
		return -EFAULT;

	/*
	 * May not be a start of buffer, set size appropriately
	 * and advance us to the beginning.
	 */
	offset = buf_addr - imu->ubuf;
	iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
	if (offset)
		iov_iter_advance(iter, offset);
860 861 862

	/* don't drop a reference to these pages */
	iter->type |= ITER_BVEC_FLAG_NO_REF;
863 864 865
	return 0;
}

J
Jens Axboe 已提交
866 867 868 869 870 871 872
static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
			   const struct sqe_submit *s, struct iovec **iovec,
			   struct iov_iter *iter)
{
	const struct io_uring_sqe *sqe = s->sqe;
	void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
	size_t sqe_len = READ_ONCE(sqe->len);
873 874 875 876 877 878 879 880 881 882 883 884 885
	u8 opcode;

	/*
	 * We're reading ->opcode for the second time, but the first read
	 * doesn't care whether it's _FIXED or not, so it doesn't matter
	 * whether ->opcode changes concurrently. The first read does care
	 * about whether it is a READ or a WRITE, so we don't trust this read
	 * for that purpose and instead let the caller pass in the read/write
	 * flag.
	 */
	opcode = READ_ONCE(sqe->opcode);
	if (opcode == IORING_OP_READ_FIXED ||
	    opcode == IORING_OP_WRITE_FIXED) {
886
		int ret = io_import_fixed(ctx, rw, sqe, iter);
887 888 889
		*iovec = NULL;
		return ret;
	}
J
Jens Axboe 已提交
890 891 892 893 894 895 896 897 898 899 900 901 902

	if (!s->has_user)
		return -EFAULT;

#ifdef CONFIG_COMPAT
	if (ctx->compat)
		return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
						iovec, iter);
#endif

	return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
}

903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921
/*
 * Make a note of the last file/offset/direction we punted to async
 * context. We'll use this information to see if we can piggy back a
 * sequential request onto the previous one, if it's still hasn't been
 * completed by the async worker.
 */
static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
{
	struct async_list *async_list = &req->ctx->pending_async[rw];
	struct kiocb *kiocb = &req->rw;
	struct file *filp = kiocb->ki_filp;
	off_t io_end = kiocb->ki_pos + len;

	if (filp == async_list->file && kiocb->ki_pos == async_list->io_end) {
		unsigned long max_pages;

		/* Use 8x RA size as a decent limiter for both reads/writes */
		max_pages = filp->f_ra.ra_pages;
		if (!max_pages)
922
			max_pages = VM_READAHEAD_PAGES;
923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943
		max_pages *= 8;

		/* If max pages are exceeded, reset the state */
		len >>= PAGE_SHIFT;
		if (async_list->io_pages + len <= max_pages) {
			req->flags |= REQ_F_SEQ_PREV;
			async_list->io_pages += len;
		} else {
			io_end = 0;
			async_list->io_pages = 0;
		}
	}

	/* New file? Reset state. */
	if (async_list->file != filp) {
		async_list->io_pages = 0;
		async_list->file = filp;
	}
	async_list->io_end = io_end;
}

944
static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
945
		   bool force_nonblock)
J
Jens Axboe 已提交
946 947 948 949 950
{
	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
	struct kiocb *kiocb = &req->rw;
	struct iov_iter iter;
	struct file *file;
951
	size_t iov_count;
952
	int ret;
J
Jens Axboe 已提交
953

954
	ret = io_prep_rw(req, s, force_nonblock);
J
Jens Axboe 已提交
955 956 957 958 959
	if (ret)
		return ret;
	file = kiocb->ki_filp;

	if (unlikely(!(file->f_mode & FMODE_READ)))
J
Jens Axboe 已提交
960
		return -EBADF;
J
Jens Axboe 已提交
961
	if (unlikely(!file->f_op->read_iter))
J
Jens Axboe 已提交
962
		return -EINVAL;
J
Jens Axboe 已提交
963 964 965

	ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
	if (ret)
J
Jens Axboe 已提交
966
		return ret;
J
Jens Axboe 已提交
967

968 969
	iov_count = iov_iter_count(&iter);
	ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
J
Jens Axboe 已提交
970 971 972 973 974
	if (!ret) {
		ssize_t ret2;

		/* Catch -EAGAIN return for forced non-blocking submission */
		ret2 = call_read_iter(file, kiocb, &iter);
975
		if (!force_nonblock || ret2 != -EAGAIN) {
J
Jens Axboe 已提交
976
			io_rw_done(kiocb, ret2);
977 978 979 980 981 982 983
		} else {
			/*
			 * If ->needs_lock is true, we're already in async
			 * context.
			 */
			if (!s->needs_lock)
				io_async_list_note(READ, req, iov_count);
J
Jens Axboe 已提交
984
			ret = -EAGAIN;
985
		}
J
Jens Axboe 已提交
986 987 988 989 990
	}
	kfree(iovec);
	return ret;
}

991
static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
992
		    bool force_nonblock)
J
Jens Axboe 已提交
993 994 995 996 997
{
	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
	struct kiocb *kiocb = &req->rw;
	struct iov_iter iter;
	struct file *file;
998
	size_t iov_count;
999
	int ret;
J
Jens Axboe 已提交
1000

1001
	ret = io_prep_rw(req, s, force_nonblock);
J
Jens Axboe 已提交
1002 1003 1004 1005 1006
	if (ret)
		return ret;

	file = kiocb->ki_filp;
	if (unlikely(!(file->f_mode & FMODE_WRITE)))
J
Jens Axboe 已提交
1007
		return -EBADF;
J
Jens Axboe 已提交
1008
	if (unlikely(!file->f_op->write_iter))
J
Jens Axboe 已提交
1009
		return -EINVAL;
J
Jens Axboe 已提交
1010 1011 1012

	ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
	if (ret)
J
Jens Axboe 已提交
1013
		return ret;
J
Jens Axboe 已提交
1014

1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025
	iov_count = iov_iter_count(&iter);

	ret = -EAGAIN;
	if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT)) {
		/* If ->needs_lock is true, we're already in async context. */
		if (!s->needs_lock)
			io_async_list_note(WRITE, req, iov_count);
		goto out_free;
	}

	ret = rw_verify_area(WRITE, file, &kiocb->ki_pos, iov_count);
J
Jens Axboe 已提交
1026
	if (!ret) {
1027 1028
		ssize_t ret2;

J
Jens Axboe 已提交
1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042
		/*
		 * Open-code file_start_write here to grab freeze protection,
		 * which will be released by another thread in
		 * io_complete_rw().  Fool lockdep by telling it the lock got
		 * released so that it doesn't complain about the held lock when
		 * we return to userspace.
		 */
		if (S_ISREG(file_inode(file)->i_mode)) {
			__sb_start_write(file_inode(file)->i_sb,
						SB_FREEZE_WRITE, true);
			__sb_writers_release(file_inode(file)->i_sb,
						SB_FREEZE_WRITE);
		}
		kiocb->ki_flags |= IOCB_WRITE;
1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055

		ret2 = call_write_iter(file, kiocb, &iter);
		if (!force_nonblock || ret2 != -EAGAIN) {
			io_rw_done(kiocb, ret2);
		} else {
			/*
			 * If ->needs_lock is true, we're already in async
			 * context.
			 */
			if (!s->needs_lock)
				io_async_list_note(WRITE, req, iov_count);
			ret = -EAGAIN;
		}
J
Jens Axboe 已提交
1056
	}
1057
out_free:
J
Jens Axboe 已提交
1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069
	kfree(iovec);
	return ret;
}

/*
 * IORING_OP_NOP just posts a completion event, nothing else.
 */
static int io_nop(struct io_kiocb *req, u64 user_data)
{
	struct io_ring_ctx *ctx = req->ctx;
	long err = 0;

J
Jens Axboe 已提交
1070 1071 1072
	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;

J
Jens Axboe 已提交
1073
	io_cqring_add_event(ctx, user_data, err, 0);
1074
	io_put_req(req);
J
Jens Axboe 已提交
1075 1076 1077
	return 0;
}

C
Christoph Hellwig 已提交
1078 1079
static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
J
Jens Axboe 已提交
1080
	struct io_ring_ctx *ctx = req->ctx;
C
Christoph Hellwig 已提交
1081

J
Jens Axboe 已提交
1082 1083
	if (!req->file)
		return -EBADF;
J
Jens Axboe 已提交
1084 1085
	/* Prep already done (EAGAIN retry) */
	if (req->flags & REQ_F_PREPPED)
C
Christoph Hellwig 已提交
1086 1087
		return 0;

J
Jens Axboe 已提交
1088
	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
J
Jens Axboe 已提交
1089
		return -EINVAL;
1090
	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
C
Christoph Hellwig 已提交
1091 1092
		return -EINVAL;

J
Jens Axboe 已提交
1093
	req->flags |= REQ_F_PREPPED;
C
Christoph Hellwig 已提交
1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
	return 0;
}

static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
		    bool force_nonblock)
{
	loff_t sqe_off = READ_ONCE(sqe->off);
	loff_t sqe_len = READ_ONCE(sqe->len);
	loff_t end = sqe_off + sqe_len;
	unsigned fsync_flags;
	int ret;

	fsync_flags = READ_ONCE(sqe->fsync_flags);
	if (unlikely(fsync_flags & ~IORING_FSYNC_DATASYNC))
		return -EINVAL;

	ret = io_prep_fsync(req, sqe);
	if (ret)
		return ret;

	/* fsync always requires a blocking context */
	if (force_nonblock)
		return -EAGAIN;

	ret = vfs_fsync_range(req->rw.ki_filp, sqe_off,
				end > 0 ? end : LLONG_MAX,
				fsync_flags & IORING_FSYNC_DATASYNC);

	io_cqring_add_event(req->ctx, sqe->user_data, ret, 0);
1123
	io_put_req(req);
C
Christoph Hellwig 已提交
1124 1125 1126
	return 0;
}

1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180
static void io_poll_remove_one(struct io_kiocb *req)
{
	struct io_poll_iocb *poll = &req->poll;

	spin_lock(&poll->head->lock);
	WRITE_ONCE(poll->canceled, true);
	if (!list_empty(&poll->wait.entry)) {
		list_del_init(&poll->wait.entry);
		queue_work(req->ctx->sqo_wq, &req->work);
	}
	spin_unlock(&poll->head->lock);

	list_del_init(&req->list);
}

static void io_poll_remove_all(struct io_ring_ctx *ctx)
{
	struct io_kiocb *req;

	spin_lock_irq(&ctx->completion_lock);
	while (!list_empty(&ctx->cancel_list)) {
		req = list_first_entry(&ctx->cancel_list, struct io_kiocb,list);
		io_poll_remove_one(req);
	}
	spin_unlock_irq(&ctx->completion_lock);
}

/*
 * Find a running poll command that matches one specified in sqe->addr,
 * and remove it if found.
 */
static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_ring_ctx *ctx = req->ctx;
	struct io_kiocb *poll_req, *next;
	int ret = -ENOENT;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
	    sqe->poll_events)
		return -EINVAL;

	spin_lock_irq(&ctx->completion_lock);
	list_for_each_entry_safe(poll_req, next, &ctx->cancel_list, list) {
		if (READ_ONCE(sqe->addr) == poll_req->user_data) {
			io_poll_remove_one(poll_req);
			ret = 0;
			break;
		}
	}
	spin_unlock_irq(&ctx->completion_lock);

	io_cqring_add_event(req->ctx, sqe->user_data, ret, 0);
1181
	io_put_req(req);
1182 1183 1184
	return 0;
}

J
Jens Axboe 已提交
1185 1186
static void io_poll_complete(struct io_ring_ctx *ctx, struct io_kiocb *req,
			     __poll_t mask)
1187
{
J
Jens Axboe 已提交
1188 1189 1190
	req->poll.done = true;
	io_cqring_fill_event(ctx, req->user_data, mangle_poll(mask), 0);
	io_commit_cqring(ctx);
1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217
}

static void io_poll_complete_work(struct work_struct *work)
{
	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
	struct io_poll_iocb *poll = &req->poll;
	struct poll_table_struct pt = { ._key = poll->events };
	struct io_ring_ctx *ctx = req->ctx;
	__poll_t mask = 0;

	if (!READ_ONCE(poll->canceled))
		mask = vfs_poll(poll->file, &pt) & poll->events;

	/*
	 * Note that ->ki_cancel callers also delete iocb from active_reqs after
	 * calling ->ki_cancel.  We need the ctx_lock roundtrip here to
	 * synchronize with them.  In the cancellation case the list_del_init
	 * itself is not actually needed, but harmless so we keep it in to
	 * avoid further branches in the fast path.
	 */
	spin_lock_irq(&ctx->completion_lock);
	if (!mask && !READ_ONCE(poll->canceled)) {
		add_wait_queue(poll->head, &poll->wait);
		spin_unlock_irq(&ctx->completion_lock);
		return;
	}
	list_del_init(&req->list);
J
Jens Axboe 已提交
1218
	io_poll_complete(ctx, req, mask);
1219 1220
	spin_unlock_irq(&ctx->completion_lock);

J
Jens Axboe 已提交
1221 1222
	io_cqring_ev_posted(ctx);
	io_put_req(req);
1223 1224 1225 1226 1227 1228 1229 1230 1231 1232
}

static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
			void *key)
{
	struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
							wait);
	struct io_kiocb *req = container_of(poll, struct io_kiocb, poll);
	struct io_ring_ctx *ctx = req->ctx;
	__poll_t mask = key_to_poll(key);
J
Jens Axboe 已提交
1233
	unsigned long flags;
1234 1235

	/* for instances that support it check for an event match first: */
J
Jens Axboe 已提交
1236 1237
	if (mask && !(mask & poll->events))
		return 0;
1238

J
Jens Axboe 已提交
1239
	list_del_init(&poll->wait.entry);
1240

J
Jens Axboe 已提交
1241 1242 1243 1244
	if (mask && spin_trylock_irqsave(&ctx->completion_lock, flags)) {
		list_del(&req->list);
		io_poll_complete(ctx, req, mask);
		spin_unlock_irqrestore(&ctx->completion_lock, flags);
1245

J
Jens Axboe 已提交
1246 1247 1248 1249
		io_cqring_ev_posted(ctx);
		io_put_req(req);
	} else {
		queue_work(ctx->sqo_wq, &req->work);
1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280
	}

	return 1;
}

struct io_poll_table {
	struct poll_table_struct pt;
	struct io_kiocb *req;
	int error;
};

static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
			       struct poll_table_struct *p)
{
	struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);

	if (unlikely(pt->req->poll.head)) {
		pt->error = -EINVAL;
		return;
	}

	pt->error = 0;
	pt->req->poll.head = head;
	add_wait_queue(head, &pt->req->poll.wait);
}

static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_poll_iocb *poll = &req->poll;
	struct io_ring_ctx *ctx = req->ctx;
	struct io_poll_table ipt;
J
Jens Axboe 已提交
1281
	bool cancel = false;
1282 1283 1284 1285 1286 1287 1288
	__poll_t mask;
	u16 events;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
		return -EINVAL;
J
Jens Axboe 已提交
1289 1290
	if (!poll->file)
		return -EBADF;
1291 1292 1293 1294 1295 1296

	INIT_WORK(&req->work, io_poll_complete_work);
	events = READ_ONCE(sqe->poll_events);
	poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;

	poll->head = NULL;
J
Jens Axboe 已提交
1297
	poll->done = false;
1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311
	poll->canceled = false;

	ipt.pt._qproc = io_poll_queue_proc;
	ipt.pt._key = poll->events;
	ipt.req = req;
	ipt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */

	/* initialized the list so that we can do list_empty checks */
	INIT_LIST_HEAD(&poll->wait.entry);
	init_waitqueue_func_entry(&poll->wait, io_poll_wake);

	mask = vfs_poll(poll->file, &ipt.pt) & poll->events;

	spin_lock_irq(&ctx->completion_lock);
J
Jens Axboe 已提交
1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329
	if (likely(poll->head)) {
		spin_lock(&poll->head->lock);
		if (unlikely(list_empty(&poll->wait.entry))) {
			if (ipt.error)
				cancel = true;
			ipt.error = 0;
			mask = 0;
		}
		if (mask || ipt.error)
			list_del_init(&poll->wait.entry);
		else if (cancel)
			WRITE_ONCE(poll->canceled, true);
		else if (!poll->done) /* actually waiting for an event */
			list_add_tail(&req->list, &ctx->cancel_list);
		spin_unlock(&poll->head->lock);
	}
	if (mask) { /* no async, we'd stolen it */
		req->error = mangle_poll(mask);
1330
		ipt.error = 0;
J
Jens Axboe 已提交
1331
		io_poll_complete(ctx, req, mask);
1332 1333 1334
	}
	spin_unlock_irq(&ctx->completion_lock);

J
Jens Axboe 已提交
1335 1336
	if (mask) {
		io_cqring_ev_posted(ctx);
1337
		io_put_req(req);
1338
	}
J
Jens Axboe 已提交
1339
	return ipt.error;
1340 1341
}

J
Jens Axboe 已提交
1342
static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
1343
			   const struct sqe_submit *s, bool force_nonblock)
J
Jens Axboe 已提交
1344
{
1345
	int ret, opcode;
J
Jens Axboe 已提交
1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356

	if (unlikely(s->index >= ctx->sq_entries))
		return -EINVAL;
	req->user_data = READ_ONCE(s->sqe->user_data);

	opcode = READ_ONCE(s->sqe->opcode);
	switch (opcode) {
	case IORING_OP_NOP:
		ret = io_nop(req, req->user_data);
		break;
	case IORING_OP_READV:
1357 1358
		if (unlikely(s->sqe->buf_index))
			return -EINVAL;
1359
		ret = io_read(req, s, force_nonblock);
J
Jens Axboe 已提交
1360 1361
		break;
	case IORING_OP_WRITEV:
1362 1363
		if (unlikely(s->sqe->buf_index))
			return -EINVAL;
1364
		ret = io_write(req, s, force_nonblock);
1365 1366
		break;
	case IORING_OP_READ_FIXED:
1367
		ret = io_read(req, s, force_nonblock);
1368 1369
		break;
	case IORING_OP_WRITE_FIXED:
1370
		ret = io_write(req, s, force_nonblock);
J
Jens Axboe 已提交
1371
		break;
C
Christoph Hellwig 已提交
1372 1373 1374
	case IORING_OP_FSYNC:
		ret = io_fsync(req, s->sqe, force_nonblock);
		break;
1375 1376 1377 1378 1379 1380
	case IORING_OP_POLL_ADD:
		ret = io_poll_add(req, s->sqe);
		break;
	case IORING_OP_POLL_REMOVE:
		ret = io_poll_remove(req, s->sqe);
		break;
J
Jens Axboe 已提交
1381 1382 1383 1384 1385
	default:
		ret = -EINVAL;
		break;
	}

J
Jens Axboe 已提交
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401
	if (ret)
		return ret;

	if (ctx->flags & IORING_SETUP_IOPOLL) {
		if (req->error == -EAGAIN)
			return -EAGAIN;

		/* workqueue context doesn't hold uring_lock, grab it now */
		if (s->needs_lock)
			mutex_lock(&ctx->uring_lock);
		io_iopoll_req_issued(req);
		if (s->needs_lock)
			mutex_unlock(&ctx->uring_lock);
	}

	return 0;
J
Jens Axboe 已提交
1402 1403
}

1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418
static struct async_list *io_async_list_from_sqe(struct io_ring_ctx *ctx,
						 const struct io_uring_sqe *sqe)
{
	switch (sqe->opcode) {
	case IORING_OP_READV:
	case IORING_OP_READ_FIXED:
		return &ctx->pending_async[READ];
	case IORING_OP_WRITEV:
	case IORING_OP_WRITE_FIXED:
		return &ctx->pending_async[WRITE];
	default:
		return NULL;
	}
}

1419 1420 1421 1422 1423 1424 1425 1426
static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
{
	u8 opcode = READ_ONCE(sqe->opcode);

	return !(opcode == IORING_OP_READ_FIXED ||
		 opcode == IORING_OP_WRITE_FIXED);
}

J
Jens Axboe 已提交
1427 1428 1429 1430
static void io_sq_wq_submit_work(struct work_struct *work)
{
	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
	struct io_ring_ctx *ctx = req->ctx;
1431 1432 1433
	struct mm_struct *cur_mm = NULL;
	struct async_list *async_list;
	LIST_HEAD(req_list);
1434
	mm_segment_t old_fs;
J
Jens Axboe 已提交
1435 1436
	int ret;

1437 1438 1439 1440 1441
	async_list = io_async_list_from_sqe(ctx, req->submit.sqe);
restart:
	do {
		struct sqe_submit *s = &req->submit;
		const struct io_uring_sqe *sqe = s->sqe;
J
Jens Axboe 已提交
1442

1443
		/* Ensure we clear previously set non-block flag */
1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461
		req->rw.ki_flags &= ~IOCB_NOWAIT;

		ret = 0;
		if (io_sqe_needs_user(sqe) && !cur_mm) {
			if (!mmget_not_zero(ctx->sqo_mm)) {
				ret = -EFAULT;
			} else {
				cur_mm = ctx->sqo_mm;
				use_mm(cur_mm);
				old_fs = get_fs();
				set_fs(USER_DS);
			}
		}

		if (!ret) {
			s->has_user = cur_mm != NULL;
			s->needs_lock = true;
			do {
1462
				ret = __io_submit_sqe(ctx, req, s, false);
1463 1464 1465 1466 1467 1468 1469 1470 1471 1472
				/*
				 * We can get EAGAIN for polled IO even though
				 * we're forcing a sync submission from here,
				 * since we can't wait for request slots on the
				 * block side.
				 */
				if (ret != -EAGAIN)
					break;
				cond_resched();
			} while (1);
1473 1474 1475

			/* drop submission reference */
			io_put_req(req);
1476 1477 1478
		}
		if (ret) {
			io_cqring_add_event(ctx, sqe->user_data, ret, 0);
1479
			io_put_req(req);
1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507
		}

		/* async context always use a copy of the sqe */
		kfree(sqe);

		if (!async_list)
			break;
		if (!list_empty(&req_list)) {
			req = list_first_entry(&req_list, struct io_kiocb,
						list);
			list_del(&req->list);
			continue;
		}
		if (list_empty(&async_list->list))
			break;

		req = NULL;
		spin_lock(&async_list->lock);
		if (list_empty(&async_list->list)) {
			spin_unlock(&async_list->lock);
			break;
		}
		list_splice_init(&async_list->list, &req_list);
		spin_unlock(&async_list->lock);

		req = list_first_entry(&req_list, struct io_kiocb, list);
		list_del(&req->list);
	} while (req);
1508 1509

	/*
1510 1511 1512
	 * Rare case of racing with a submitter. If we find the count has
	 * dropped to zero AND we have pending work items, then restart
	 * the processing. This is a tiny race window.
1513
	 */
1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528
	if (async_list) {
		ret = atomic_dec_return(&async_list->cnt);
		while (!ret && !list_empty(&async_list->list)) {
			spin_lock(&async_list->lock);
			atomic_inc(&async_list->cnt);
			list_splice_init(&async_list->list, &req_list);
			spin_unlock(&async_list->lock);

			if (!list_empty(&req_list)) {
				req = list_first_entry(&req_list,
							struct io_kiocb, list);
				list_del(&req->list);
				goto restart;
			}
			ret = atomic_dec_return(&async_list->cnt);
1529 1530
		}
	}
J
Jens Axboe 已提交
1531

1532
	if (cur_mm) {
1533
		set_fs(old_fs);
1534 1535
		unuse_mm(cur_mm);
		mmput(cur_mm);
J
Jens Axboe 已提交
1536
	}
1537
}
J
Jens Axboe 已提交
1538

1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
/*
 * See if we can piggy back onto previously submitted work, that is still
 * running. We currently only allow this if the new request is sequential
 * to the previous one we punted.
 */
static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
{
	bool ret = false;

	if (!list)
		return false;
	if (!(req->flags & REQ_F_SEQ_PREV))
		return false;
	if (!atomic_read(&list->cnt))
		return false;

	ret = true;
	spin_lock(&list->lock);
	list_add_tail(&req->list, &list->list);
	if (!atomic_read(&list->cnt)) {
		list_del_init(&req->list);
		ret = false;
	}
	spin_unlock(&list->lock);
	return ret;
J
Jens Axboe 已提交
1564 1565
}

J
Jens Axboe 已提交
1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609
static bool io_op_needs_file(const struct io_uring_sqe *sqe)
{
	int op = READ_ONCE(sqe->opcode);

	switch (op) {
	case IORING_OP_NOP:
	case IORING_OP_POLL_REMOVE:
		return false;
	default:
		return true;
	}
}

static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
			   struct io_submit_state *state, struct io_kiocb *req)
{
	unsigned flags;
	int fd;

	flags = READ_ONCE(s->sqe->flags);
	fd = READ_ONCE(s->sqe->fd);

	if (!io_op_needs_file(s->sqe)) {
		req->file = NULL;
		return 0;
	}

	if (flags & IOSQE_FIXED_FILE) {
		if (unlikely(!ctx->user_files ||
		    (unsigned) fd >= ctx->nr_user_files))
			return -EBADF;
		req->file = ctx->user_files[fd];
		req->flags |= REQ_F_FIXED_FILE;
	} else {
		if (s->needs_fixed_file)
			return -EBADF;
		req->file = io_file_get(state, fd);
		if (unlikely(!req->file))
			return -EBADF;
	}

	return 0;
}

1610 1611
static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
			 struct io_submit_state *state)
J
Jens Axboe 已提交
1612 1613
{
	struct io_kiocb *req;
1614
	int ret;
J
Jens Axboe 已提交
1615 1616

	/* enforce forwards compatibility on users */
J
Jens Axboe 已提交
1617
	if (unlikely(s->sqe->flags & ~IOSQE_FIXED_FILE))
J
Jens Axboe 已提交
1618 1619
		return -EINVAL;

J
Jens Axboe 已提交
1620
	req = io_get_req(ctx, state);
J
Jens Axboe 已提交
1621 1622 1623
	if (unlikely(!req))
		return -EAGAIN;

J
Jens Axboe 已提交
1624 1625 1626
	ret = io_req_set_file(ctx, s, state, req);
	if (unlikely(ret))
		goto out;
J
Jens Axboe 已提交
1627

1628
	ret = __io_submit_sqe(ctx, req, s, true);
1629
	if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
J
Jens Axboe 已提交
1630 1631 1632 1633
		struct io_uring_sqe *sqe_copy;

		sqe_copy = kmalloc(sizeof(*sqe_copy), GFP_KERNEL);
		if (sqe_copy) {
1634 1635
			struct async_list *list;

J
Jens Axboe 已提交
1636 1637 1638 1639
			memcpy(sqe_copy, s->sqe, sizeof(*sqe_copy));
			s->sqe = sqe_copy;

			memcpy(&req->submit, s, sizeof(*s));
1640 1641 1642 1643 1644 1645 1646
			list = io_async_list_from_sqe(ctx, s->sqe);
			if (!io_add_to_prev_work(list, req)) {
				if (list)
					atomic_inc(&list->cnt);
				INIT_WORK(&req->work, io_sq_wq_submit_work);
				queue_work(ctx->sqo_wq, &req->work);
			}
1647 1648 1649 1650 1651 1652 1653

			/*
			 * Queued up for async execution, worker will release
			 * submit reference when the iocb is actually
			 * submitted.
			 */
			return 0;
J
Jens Axboe 已提交
1654 1655
		}
	}
1656

J
Jens Axboe 已提交
1657
out:
1658 1659 1660 1661
	/* drop submission reference */
	io_put_req(req);

	/* and drop final reference, if we failed */
J
Jens Axboe 已提交
1662
	if (ret)
1663
		io_put_req(req);
J
Jens Axboe 已提交
1664 1665 1666 1667

	return ret;
}

1668 1669 1670 1671 1672 1673
/*
 * Batched submission is done, ensure local IO is flushed out.
 */
static void io_submit_state_end(struct io_submit_state *state)
{
	blk_finish_plug(&state->plug);
1674
	io_file_put(state);
J
Jens Axboe 已提交
1675 1676 1677
	if (state->free_reqs)
		kmem_cache_free_bulk(req_cachep, state->free_reqs,
					&state->reqs[state->cur_req]);
1678 1679 1680 1681 1682 1683 1684 1685 1686
}

/*
 * Start submission side cache.
 */
static void io_submit_state_start(struct io_submit_state *state,
				  struct io_ring_ctx *ctx, unsigned max_ios)
{
	blk_start_plug(&state->plug);
J
Jens Axboe 已提交
1687
	state->free_reqs = 0;
1688 1689 1690 1691
	state->file = NULL;
	state->ios_left = max_ios;
}

J
Jens Axboe 已提交
1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743
static void io_commit_sqring(struct io_ring_ctx *ctx)
{
	struct io_sq_ring *ring = ctx->sq_ring;

	if (ctx->cached_sq_head != READ_ONCE(ring->r.head)) {
		/*
		 * Ensure any loads from the SQEs are done at this point,
		 * since once we write the new head, the application could
		 * write new data to them.
		 */
		smp_store_release(&ring->r.head, ctx->cached_sq_head);

		/*
		 * write side barrier of head update, app has read side. See
		 * comment at the top of this file
		 */
		smp_wmb();
	}
}

/*
 * Undo last io_get_sqring()
 */
static void io_drop_sqring(struct io_ring_ctx *ctx)
{
	ctx->cached_sq_head--;
}

/*
 * Fetch an sqe, if one is available. Note that s->sqe will point to memory
 * that is mapped by userspace. This means that care needs to be taken to
 * ensure that reads are stable, as we cannot rely on userspace always
 * being a good citizen. If members of the sqe are validated and then later
 * used, it's important that those reads are done through READ_ONCE() to
 * prevent a re-load down the line.
 */
static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
{
	struct io_sq_ring *ring = ctx->sq_ring;
	unsigned head;

	/*
	 * The cached sq head (or cq tail) serves two purposes:
	 *
	 * 1) allows us to batch the cost of updating the user visible
	 *    head updates.
	 * 2) allows the kernel side to track the head on its own, even
	 *    though the application is the one updating it.
	 */
	head = ctx->cached_sq_head;
	/* See comment at the top of this file */
	smp_rmb();
1744 1745
	/* make sure SQ entry isn't read before tail */
	if (head == smp_load_acquire(&ring->r.tail))
J
Jens Axboe 已提交
1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763
		return false;

	head = READ_ONCE(ring->array[head & ctx->sq_mask]);
	if (head < ctx->sq_entries) {
		s->index = head;
		s->sqe = &ctx->sq_sqes[head];
		ctx->cached_sq_head++;
		return true;
	}

	/* drop invalid entries */
	ctx->cached_sq_head++;
	ring->dropped++;
	/* See comment at the top of this file */
	smp_wmb();
	return false;
}

J
Jens Axboe 已提交
1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869
static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
			  unsigned int nr, bool has_user, bool mm_fault)
{
	struct io_submit_state state, *statep = NULL;
	int ret, i, submitted = 0;

	if (nr > IO_PLUG_THRESHOLD) {
		io_submit_state_start(&state, ctx, nr);
		statep = &state;
	}

	for (i = 0; i < nr; i++) {
		if (unlikely(mm_fault)) {
			ret = -EFAULT;
		} else {
			sqes[i].has_user = has_user;
			sqes[i].needs_lock = true;
			sqes[i].needs_fixed_file = true;
			ret = io_submit_sqe(ctx, &sqes[i], statep);
		}
		if (!ret) {
			submitted++;
			continue;
		}

		io_cqring_add_event(ctx, sqes[i].sqe->user_data, ret, 0);
	}

	if (statep)
		io_submit_state_end(&state);

	return submitted;
}

static int io_sq_thread(void *data)
{
	struct sqe_submit sqes[IO_IOPOLL_BATCH];
	struct io_ring_ctx *ctx = data;
	struct mm_struct *cur_mm = NULL;
	mm_segment_t old_fs;
	DEFINE_WAIT(wait);
	unsigned inflight;
	unsigned long timeout;

	old_fs = get_fs();
	set_fs(USER_DS);

	timeout = inflight = 0;
	while (!kthread_should_stop() && !ctx->sqo_stop) {
		bool all_fixed, mm_fault = false;
		int i;

		if (inflight) {
			unsigned nr_events = 0;

			if (ctx->flags & IORING_SETUP_IOPOLL) {
				/*
				 * We disallow the app entering submit/complete
				 * with polling, but we still need to lock the
				 * ring to prevent racing with polled issue
				 * that got punted to a workqueue.
				 */
				mutex_lock(&ctx->uring_lock);
				io_iopoll_check(ctx, &nr_events, 0);
				mutex_unlock(&ctx->uring_lock);
			} else {
				/*
				 * Normal IO, just pretend everything completed.
				 * We don't have to poll completions for that.
				 */
				nr_events = inflight;
			}

			inflight -= nr_events;
			if (!inflight)
				timeout = jiffies + ctx->sq_thread_idle;
		}

		if (!io_get_sqring(ctx, &sqes[0])) {
			/*
			 * We're polling. If we're within the defined idle
			 * period, then let us spin without work before going
			 * to sleep.
			 */
			if (inflight || !time_after(jiffies, timeout)) {
				cpu_relax();
				continue;
			}

			/*
			 * Drop cur_mm before scheduling, we can't hold it for
			 * long periods (or over schedule()). Do this before
			 * adding ourselves to the waitqueue, as the unuse/drop
			 * may sleep.
			 */
			if (cur_mm) {
				unuse_mm(cur_mm);
				mmput(cur_mm);
				cur_mm = NULL;
			}

			prepare_to_wait(&ctx->sqo_wait, &wait,
						TASK_INTERRUPTIBLE);

			/* Tell userspace we may need a wakeup call */
			ctx->sq_ring->flags |= IORING_SQ_NEED_WAKEUP;
1870 1871
			/* make sure to read SQ tail after writing flags */
			smp_mb();
J
Jens Axboe 已提交
1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924

			if (!io_get_sqring(ctx, &sqes[0])) {
				if (kthread_should_stop()) {
					finish_wait(&ctx->sqo_wait, &wait);
					break;
				}
				if (signal_pending(current))
					flush_signals(current);
				schedule();
				finish_wait(&ctx->sqo_wait, &wait);

				ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP;
				smp_wmb();
				continue;
			}
			finish_wait(&ctx->sqo_wait, &wait);

			ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP;
			smp_wmb();
		}

		i = 0;
		all_fixed = true;
		do {
			if (all_fixed && io_sqe_needs_user(sqes[i].sqe))
				all_fixed = false;

			i++;
			if (i == ARRAY_SIZE(sqes))
				break;
		} while (io_get_sqring(ctx, &sqes[i]));

		/* Unless all new commands are FIXED regions, grab mm */
		if (!all_fixed && !cur_mm) {
			mm_fault = !mmget_not_zero(ctx->sqo_mm);
			if (!mm_fault) {
				use_mm(ctx->sqo_mm);
				cur_mm = ctx->sqo_mm;
			}
		}

		inflight += io_submit_sqes(ctx, sqes, i, cur_mm != NULL,
						mm_fault);

		/* Commit SQ ring head once we've consumed all SQEs */
		io_commit_sqring(ctx);
	}

	set_fs(old_fs);
	if (cur_mm) {
		unuse_mm(cur_mm);
		mmput(cur_mm);
	}
1925 1926 1927 1928

	if (kthread_should_park())
		kthread_parkme();

J
Jens Axboe 已提交
1929 1930 1931
	return 0;
}

J
Jens Axboe 已提交
1932 1933
static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
{
1934
	struct io_submit_state state, *statep = NULL;
J
Jens Axboe 已提交
1935 1936
	int i, ret = 0, submit = 0;

1937 1938 1939 1940
	if (to_submit > IO_PLUG_THRESHOLD) {
		io_submit_state_start(&state, ctx, to_submit);
		statep = &state;
	}
J
Jens Axboe 已提交
1941 1942 1943 1944 1945 1946 1947 1948

	for (i = 0; i < to_submit; i++) {
		struct sqe_submit s;

		if (!io_get_sqring(ctx, &s))
			break;

		s.has_user = true;
J
Jens Axboe 已提交
1949
		s.needs_lock = false;
J
Jens Axboe 已提交
1950
		s.needs_fixed_file = false;
J
Jens Axboe 已提交
1951

1952
		ret = io_submit_sqe(ctx, &s, statep);
J
Jens Axboe 已提交
1953 1954 1955 1956 1957 1958 1959 1960 1961
		if (ret) {
			io_drop_sqring(ctx);
			break;
		}

		submit++;
	}
	io_commit_sqring(ctx);

1962 1963
	if (statep)
		io_submit_state_end(statep);
J
Jens Axboe 已提交
1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990

	return submit ? submit : ret;
}

static unsigned io_cqring_events(struct io_cq_ring *ring)
{
	return READ_ONCE(ring->r.tail) - READ_ONCE(ring->r.head);
}

/*
 * Wait until events become available, if we don't already have some. The
 * application must reap them itself, as they reside on the shared cq ring.
 */
static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
			  const sigset_t __user *sig, size_t sigsz)
{
	struct io_cq_ring *ring = ctx->cq_ring;
	sigset_t ksigmask, sigsaved;
	DEFINE_WAIT(wait);
	int ret;

	/* See comment at the top of this file */
	smp_rmb();
	if (io_cqring_events(ring) >= min_events)
		return 0;

	if (sig) {
1991 1992 1993 1994 1995 1996 1997 1998 1999
#ifdef CONFIG_COMPAT
		if (in_compat_syscall())
			ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
						      &ksigmask, &sigsaved, sigsz);
		else
#endif
			ret = set_user_sigmask(sig, &ksigmask,
					       &sigsaved, sigsz);

J
Jens Axboe 已提交
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027
		if (ret)
			return ret;
	}

	do {
		prepare_to_wait(&ctx->wait, &wait, TASK_INTERRUPTIBLE);

		ret = 0;
		/* See comment at the top of this file */
		smp_rmb();
		if (io_cqring_events(ring) >= min_events)
			break;

		schedule();

		ret = -EINTR;
		if (signal_pending(current))
			break;
	} while (1);

	finish_wait(&ctx->wait, &wait);

	if (sig)
		restore_user_sigmask(sig, &sigsaved);

	return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.tail) ? ret : 0;
}

J
Jens Axboe 已提交
2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057
static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
{
#if defined(CONFIG_UNIX)
	if (ctx->ring_sock) {
		struct sock *sock = ctx->ring_sock->sk;
		struct sk_buff *skb;

		while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
			kfree_skb(skb);
	}
#else
	int i;

	for (i = 0; i < ctx->nr_user_files; i++)
		fput(ctx->user_files[i]);
#endif
}

static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
{
	if (!ctx->user_files)
		return -ENXIO;

	__io_sqe_files_unregister(ctx);
	kfree(ctx->user_files);
	ctx->user_files = NULL;
	ctx->nr_user_files = 0;
	return 0;
}

J
Jens Axboe 已提交
2058 2059 2060 2061 2062
static void io_sq_thread_stop(struct io_ring_ctx *ctx)
{
	if (ctx->sqo_thread) {
		ctx->sqo_stop = 1;
		mb();
2063
		kthread_park(ctx->sqo_thread);
J
Jens Axboe 已提交
2064 2065 2066 2067 2068
		kthread_stop(ctx->sqo_thread);
		ctx->sqo_thread = NULL;
	}
}

J
Jens Axboe 已提交
2069 2070
static void io_finish_async(struct io_ring_ctx *ctx)
{
J
Jens Axboe 已提交
2071 2072
	io_sq_thread_stop(ctx);

J
Jens Axboe 已提交
2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224
	if (ctx->sqo_wq) {
		destroy_workqueue(ctx->sqo_wq);
		ctx->sqo_wq = NULL;
	}
}

#if defined(CONFIG_UNIX)
static void io_destruct_skb(struct sk_buff *skb)
{
	struct io_ring_ctx *ctx = skb->sk->sk_user_data;

	io_finish_async(ctx);
	unix_destruct_scm(skb);
}

/*
 * Ensure the UNIX gc is aware of our file set, so we are certain that
 * the io_uring can be safely unregistered on process exit, even if we have
 * loops in the file referencing.
 */
static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
{
	struct sock *sk = ctx->ring_sock->sk;
	struct scm_fp_list *fpl;
	struct sk_buff *skb;
	int i;

	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
		unsigned long inflight = ctx->user->unix_inflight + nr;

		if (inflight > task_rlimit(current, RLIMIT_NOFILE))
			return -EMFILE;
	}

	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
	if (!fpl)
		return -ENOMEM;

	skb = alloc_skb(0, GFP_KERNEL);
	if (!skb) {
		kfree(fpl);
		return -ENOMEM;
	}

	skb->sk = sk;
	skb->destructor = io_destruct_skb;

	fpl->user = get_uid(ctx->user);
	for (i = 0; i < nr; i++) {
		fpl->fp[i] = get_file(ctx->user_files[i + offset]);
		unix_inflight(fpl->user, fpl->fp[i]);
	}

	fpl->max = fpl->count = nr;
	UNIXCB(skb).fp = fpl;
	refcount_add(skb->truesize, &sk->sk_wmem_alloc);
	skb_queue_head(&sk->sk_receive_queue, skb);

	for (i = 0; i < nr; i++)
		fput(fpl->fp[i]);

	return 0;
}

/*
 * If UNIX sockets are enabled, fd passing can cause a reference cycle which
 * causes regular reference counting to break down. We rely on the UNIX
 * garbage collection to take care of this problem for us.
 */
static int io_sqe_files_scm(struct io_ring_ctx *ctx)
{
	unsigned left, total;
	int ret = 0;

	total = 0;
	left = ctx->nr_user_files;
	while (left) {
		unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
		int ret;

		ret = __io_sqe_files_scm(ctx, this_files, total);
		if (ret)
			break;
		left -= this_files;
		total += this_files;
	}

	if (!ret)
		return 0;

	while (total < ctx->nr_user_files) {
		fput(ctx->user_files[total]);
		total++;
	}

	return ret;
}
#else
static int io_sqe_files_scm(struct io_ring_ctx *ctx)
{
	return 0;
}
#endif

static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
				 unsigned nr_args)
{
	__s32 __user *fds = (__s32 __user *) arg;
	int fd, ret = 0;
	unsigned i;

	if (ctx->user_files)
		return -EBUSY;
	if (!nr_args)
		return -EINVAL;
	if (nr_args > IORING_MAX_FIXED_FILES)
		return -EMFILE;

	ctx->user_files = kcalloc(nr_args, sizeof(struct file *), GFP_KERNEL);
	if (!ctx->user_files)
		return -ENOMEM;

	for (i = 0; i < nr_args; i++) {
		ret = -EFAULT;
		if (copy_from_user(&fd, &fds[i], sizeof(fd)))
			break;

		ctx->user_files[i] = fget(fd);

		ret = -EBADF;
		if (!ctx->user_files[i])
			break;
		/*
		 * Don't allow io_uring instances to be registered. If UNIX
		 * isn't enabled, then this causes a reference cycle and this
		 * instance can never get freed. If UNIX is enabled we'll
		 * handle it just fine, but there's still no point in allowing
		 * a ring fd as it doesn't support regular read/write anyway.
		 */
		if (ctx->user_files[i]->f_op == &io_uring_fops) {
			fput(ctx->user_files[i]);
			break;
		}
		ctx->nr_user_files++;
		ret = 0;
	}

	if (ret) {
		for (i = 0; i < ctx->nr_user_files; i++)
			fput(ctx->user_files[i]);

		kfree(ctx->user_files);
2225
		ctx->user_files = NULL;
J
Jens Axboe 已提交
2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236
		ctx->nr_user_files = 0;
		return ret;
	}

	ret = io_sqe_files_scm(ctx);
	if (ret)
		io_sqe_files_unregister(ctx);

	return ret;
}

J
Jens Axboe 已提交
2237 2238
static int io_sq_offload_start(struct io_ring_ctx *ctx,
			       struct io_uring_params *p)
J
Jens Axboe 已提交
2239 2240 2241
{
	int ret;

J
Jens Axboe 已提交
2242
	init_waitqueue_head(&ctx->sqo_wait);
J
Jens Axboe 已提交
2243 2244 2245
	mmgrab(current->mm);
	ctx->sqo_mm = current->mm;

J
Jens Axboe 已提交
2246 2247 2248 2249 2250
	ret = -EINVAL;
	if (!cpu_possible(p->sq_thread_cpu))
		goto err;

	if (ctx->flags & IORING_SETUP_SQPOLL) {
2251 2252 2253 2254
		ret = -EPERM;
		if (!capable(CAP_SYS_ADMIN))
			goto err;

2255 2256 2257 2258
		ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
		if (!ctx->sq_thread_idle)
			ctx->sq_thread_idle = HZ;

J
Jens Axboe 已提交
2259 2260 2261 2262
		if (p->flags & IORING_SETUP_SQ_AFF) {
			int cpu;

			cpu = array_index_nospec(p->sq_thread_cpu, NR_CPUS);
2263 2264 2265 2266
			ret = -EINVAL;
			if (!cpu_possible(p->sq_thread_cpu))
				goto err;

J
Jens Axboe 已提交
2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285
			ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread,
							ctx, cpu,
							"io_uring-sq");
		} else {
			ctx->sqo_thread = kthread_create(io_sq_thread, ctx,
							"io_uring-sq");
		}
		if (IS_ERR(ctx->sqo_thread)) {
			ret = PTR_ERR(ctx->sqo_thread);
			ctx->sqo_thread = NULL;
			goto err;
		}
		wake_up_process(ctx->sqo_thread);
	} else if (p->flags & IORING_SETUP_SQ_AFF) {
		/* Can't have SQ_AFF without SQPOLL */
		ret = -EINVAL;
		goto err;
	}

J
Jens Axboe 已提交
2286 2287 2288 2289 2290 2291 2292 2293 2294 2295
	/* Do QD, or 2 * CPUS, whatever is smallest */
	ctx->sqo_wq = alloc_workqueue("io_ring-wq", WQ_UNBOUND | WQ_FREEZABLE,
			min(ctx->sq_entries - 1, 2 * num_online_cpus()));
	if (!ctx->sqo_wq) {
		ret = -ENOMEM;
		goto err;
	}

	return 0;
err:
J
Jens Axboe 已提交
2296
	io_sq_thread_stop(ctx);
J
Jens Axboe 已提交
2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353
	mmdrop(ctx->sqo_mm);
	ctx->sqo_mm = NULL;
	return ret;
}

static void io_unaccount_mem(struct user_struct *user, unsigned long nr_pages)
{
	atomic_long_sub(nr_pages, &user->locked_vm);
}

static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
{
	unsigned long page_limit, cur_pages, new_pages;

	/* Don't allow more pages than we can safely lock */
	page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	do {
		cur_pages = atomic_long_read(&user->locked_vm);
		new_pages = cur_pages + nr_pages;
		if (new_pages > page_limit)
			return -ENOMEM;
	} while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
					new_pages) != cur_pages);

	return 0;
}

static void io_mem_free(void *ptr)
{
	struct page *page = virt_to_head_page(ptr);

	if (put_page_testzero(page))
		free_compound_page(page);
}

static void *io_mem_alloc(size_t size)
{
	gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP |
				__GFP_NORETRY;

	return (void *) __get_free_pages(gfp_flags, get_order(size));
}

static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
{
	struct io_sq_ring *sq_ring;
	struct io_cq_ring *cq_ring;
	size_t bytes;

	bytes = struct_size(sq_ring, array, sq_entries);
	bytes += array_size(sizeof(struct io_uring_sqe), sq_entries);
	bytes += struct_size(cq_ring, cqes, cq_entries);

	return (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
}

2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545
static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
{
	int i, j;

	if (!ctx->user_bufs)
		return -ENXIO;

	for (i = 0; i < ctx->nr_user_bufs; i++) {
		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];

		for (j = 0; j < imu->nr_bvecs; j++)
			put_page(imu->bvec[j].bv_page);

		if (ctx->account_mem)
			io_unaccount_mem(ctx->user, imu->nr_bvecs);
		kfree(imu->bvec);
		imu->nr_bvecs = 0;
	}

	kfree(ctx->user_bufs);
	ctx->user_bufs = NULL;
	ctx->nr_user_bufs = 0;
	return 0;
}

static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
		       void __user *arg, unsigned index)
{
	struct iovec __user *src;

#ifdef CONFIG_COMPAT
	if (ctx->compat) {
		struct compat_iovec __user *ciovs;
		struct compat_iovec ciov;

		ciovs = (struct compat_iovec __user *) arg;
		if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
			return -EFAULT;

		dst->iov_base = (void __user *) (unsigned long) ciov.iov_base;
		dst->iov_len = ciov.iov_len;
		return 0;
	}
#endif
	src = (struct iovec __user *) arg;
	if (copy_from_user(dst, &src[index], sizeof(*dst)))
		return -EFAULT;
	return 0;
}

static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
				  unsigned nr_args)
{
	struct vm_area_struct **vmas = NULL;
	struct page **pages = NULL;
	int i, j, got_pages = 0;
	int ret = -EINVAL;

	if (ctx->user_bufs)
		return -EBUSY;
	if (!nr_args || nr_args > UIO_MAXIOV)
		return -EINVAL;

	ctx->user_bufs = kcalloc(nr_args, sizeof(struct io_mapped_ubuf),
					GFP_KERNEL);
	if (!ctx->user_bufs)
		return -ENOMEM;

	for (i = 0; i < nr_args; i++) {
		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
		unsigned long off, start, end, ubuf;
		int pret, nr_pages;
		struct iovec iov;
		size_t size;

		ret = io_copy_iov(ctx, &iov, arg, i);
		if (ret)
			break;

		/*
		 * Don't impose further limits on the size and buffer
		 * constraints here, we'll -EINVAL later when IO is
		 * submitted if they are wrong.
		 */
		ret = -EFAULT;
		if (!iov.iov_base || !iov.iov_len)
			goto err;

		/* arbitrary limit, but we need something */
		if (iov.iov_len > SZ_1G)
			goto err;

		ubuf = (unsigned long) iov.iov_base;
		end = (ubuf + iov.iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		start = ubuf >> PAGE_SHIFT;
		nr_pages = end - start;

		if (ctx->account_mem) {
			ret = io_account_mem(ctx->user, nr_pages);
			if (ret)
				goto err;
		}

		ret = 0;
		if (!pages || nr_pages > got_pages) {
			kfree(vmas);
			kfree(pages);
			pages = kmalloc_array(nr_pages, sizeof(struct page *),
						GFP_KERNEL);
			vmas = kmalloc_array(nr_pages,
					sizeof(struct vm_area_struct *),
					GFP_KERNEL);
			if (!pages || !vmas) {
				ret = -ENOMEM;
				if (ctx->account_mem)
					io_unaccount_mem(ctx->user, nr_pages);
				goto err;
			}
			got_pages = nr_pages;
		}

		imu->bvec = kmalloc_array(nr_pages, sizeof(struct bio_vec),
						GFP_KERNEL);
		ret = -ENOMEM;
		if (!imu->bvec) {
			if (ctx->account_mem)
				io_unaccount_mem(ctx->user, nr_pages);
			goto err;
		}

		ret = 0;
		down_read(&current->mm->mmap_sem);
		pret = get_user_pages_longterm(ubuf, nr_pages, FOLL_WRITE,
						pages, vmas);
		if (pret == nr_pages) {
			/* don't support file backed memory */
			for (j = 0; j < nr_pages; j++) {
				struct vm_area_struct *vma = vmas[j];

				if (vma->vm_file &&
				    !is_file_hugepages(vma->vm_file)) {
					ret = -EOPNOTSUPP;
					break;
				}
			}
		} else {
			ret = pret < 0 ? pret : -EFAULT;
		}
		up_read(&current->mm->mmap_sem);
		if (ret) {
			/*
			 * if we did partial map, or found file backed vmas,
			 * release any pages we did get
			 */
			if (pret > 0) {
				for (j = 0; j < pret; j++)
					put_page(pages[j]);
			}
			if (ctx->account_mem)
				io_unaccount_mem(ctx->user, nr_pages);
			goto err;
		}

		off = ubuf & ~PAGE_MASK;
		size = iov.iov_len;
		for (j = 0; j < nr_pages; j++) {
			size_t vec_len;

			vec_len = min_t(size_t, size, PAGE_SIZE - off);
			imu->bvec[j].bv_page = pages[j];
			imu->bvec[j].bv_len = vec_len;
			imu->bvec[j].bv_offset = off;
			off = 0;
			size -= vec_len;
		}
		/* store original address for later verification */
		imu->ubuf = ubuf;
		imu->len = iov.iov_len;
		imu->nr_bvecs = nr_pages;

		ctx->nr_user_bufs++;
	}
	kfree(pages);
	kfree(vmas);
	return 0;
err:
	kfree(pages);
	kfree(vmas);
	io_sqe_buffer_unregister(ctx);
	return ret;
}

J
Jens Axboe 已提交
2546 2547
static void io_ring_ctx_free(struct io_ring_ctx *ctx)
{
J
Jens Axboe 已提交
2548
	io_finish_async(ctx);
J
Jens Axboe 已提交
2549 2550
	if (ctx->sqo_mm)
		mmdrop(ctx->sqo_mm);
J
Jens Axboe 已提交
2551 2552

	io_iopoll_reap_events(ctx);
2553
	io_sqe_buffer_unregister(ctx);
J
Jens Axboe 已提交
2554
	io_sqe_files_unregister(ctx);
J
Jens Axboe 已提交
2555

J
Jens Axboe 已提交
2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580
#if defined(CONFIG_UNIX)
	if (ctx->ring_sock)
		sock_release(ctx->ring_sock);
#endif

	io_mem_free(ctx->sq_ring);
	io_mem_free(ctx->sq_sqes);
	io_mem_free(ctx->cq_ring);

	percpu_ref_exit(&ctx->refs);
	if (ctx->account_mem)
		io_unaccount_mem(ctx->user,
				ring_pages(ctx->sq_entries, ctx->cq_entries));
	free_uid(ctx->user);
	kfree(ctx);
}

static __poll_t io_uring_poll(struct file *file, poll_table *wait)
{
	struct io_ring_ctx *ctx = file->private_data;
	__poll_t mask = 0;

	poll_wait(file, &ctx->cq_wait, wait);
	/* See comment at the top of this file */
	smp_rmb();
2581 2582
	if (READ_ONCE(ctx->sq_ring->r.tail) - ctx->cached_sq_head !=
	    ctx->sq_ring->ring_entries)
J
Jens Axboe 已提交
2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602
		mask |= EPOLLOUT | EPOLLWRNORM;
	if (READ_ONCE(ctx->cq_ring->r.head) != ctx->cached_cq_tail)
		mask |= EPOLLIN | EPOLLRDNORM;

	return mask;
}

static int io_uring_fasync(int fd, struct file *file, int on)
{
	struct io_ring_ctx *ctx = file->private_data;

	return fasync_helper(fd, file, on, &ctx->cq_fasync);
}

static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
{
	mutex_lock(&ctx->uring_lock);
	percpu_ref_kill(&ctx->refs);
	mutex_unlock(&ctx->uring_lock);

2603
	io_poll_remove_all(ctx);
J
Jens Axboe 已提交
2604
	io_iopoll_reap_events(ctx);
J
Jens Axboe 已提交
2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657
	wait_for_completion(&ctx->ctx_done);
	io_ring_ctx_free(ctx);
}

static int io_uring_release(struct inode *inode, struct file *file)
{
	struct io_ring_ctx *ctx = file->private_data;

	file->private_data = NULL;
	io_ring_ctx_wait_and_kill(ctx);
	return 0;
}

static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
{
	loff_t offset = (loff_t) vma->vm_pgoff << PAGE_SHIFT;
	unsigned long sz = vma->vm_end - vma->vm_start;
	struct io_ring_ctx *ctx = file->private_data;
	unsigned long pfn;
	struct page *page;
	void *ptr;

	switch (offset) {
	case IORING_OFF_SQ_RING:
		ptr = ctx->sq_ring;
		break;
	case IORING_OFF_SQES:
		ptr = ctx->sq_sqes;
		break;
	case IORING_OFF_CQ_RING:
		ptr = ctx->cq_ring;
		break;
	default:
		return -EINVAL;
	}

	page = virt_to_head_page(ptr);
	if (sz > (PAGE_SIZE << compound_order(page)))
		return -EINVAL;

	pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
	return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
}

SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
		u32, min_complete, u32, flags, const sigset_t __user *, sig,
		size_t, sigsz)
{
	struct io_ring_ctx *ctx;
	long ret = -EBADF;
	int submitted = 0;
	struct fd f;

J
Jens Axboe 已提交
2658
	if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP))
J
Jens Axboe 已提交
2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673
		return -EINVAL;

	f = fdget(fd);
	if (!f.file)
		return -EBADF;

	ret = -EOPNOTSUPP;
	if (f.file->f_op != &io_uring_fops)
		goto out_fput;

	ret = -ENXIO;
	ctx = f.file->private_data;
	if (!percpu_ref_tryget(&ctx->refs))
		goto out_fput;

J
Jens Axboe 已提交
2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685
	/*
	 * For SQ polling, the thread will do all submissions and completions.
	 * Just return the requested submit count, and wake the thread if
	 * we were asked to.
	 */
	if (ctx->flags & IORING_SETUP_SQPOLL) {
		if (flags & IORING_ENTER_SQ_WAKEUP)
			wake_up(&ctx->sqo_wait);
		submitted = to_submit;
		goto out_ctx;
	}

J
Jens Axboe 已提交
2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697
	ret = 0;
	if (to_submit) {
		to_submit = min(to_submit, ctx->sq_entries);

		mutex_lock(&ctx->uring_lock);
		submitted = io_ring_submit(ctx, to_submit);
		mutex_unlock(&ctx->uring_lock);

		if (submitted < 0)
			goto out_ctx;
	}
	if (flags & IORING_ENTER_GETEVENTS) {
J
Jens Axboe 已提交
2698 2699
		unsigned nr_events = 0;

J
Jens Axboe 已提交
2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710
		min_complete = min(min_complete, ctx->cq_entries);

		/*
		 * The application could have included the 'to_submit' count
		 * in how many events it wanted to wait for. If we failed to
		 * submit the desired count, we may need to adjust the number
		 * of events to poll/wait for.
		 */
		if (submitted < to_submit)
			min_complete = min_t(unsigned, submitted, min_complete);

J
Jens Axboe 已提交
2711 2712 2713 2714 2715 2716 2717
		if (ctx->flags & IORING_SETUP_IOPOLL) {
			mutex_lock(&ctx->uring_lock);
			ret = io_iopoll_check(ctx, &nr_events, min_complete);
			mutex_unlock(&ctx->uring_lock);
		} else {
			ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
		}
J
Jens Axboe 已提交
2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807
	}

out_ctx:
	io_ring_drop_ctx_refs(ctx, 1);
out_fput:
	fdput(f);
	return submitted ? submitted : ret;
}

static const struct file_operations io_uring_fops = {
	.release	= io_uring_release,
	.mmap		= io_uring_mmap,
	.poll		= io_uring_poll,
	.fasync		= io_uring_fasync,
};

static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
				  struct io_uring_params *p)
{
	struct io_sq_ring *sq_ring;
	struct io_cq_ring *cq_ring;
	size_t size;

	sq_ring = io_mem_alloc(struct_size(sq_ring, array, p->sq_entries));
	if (!sq_ring)
		return -ENOMEM;

	ctx->sq_ring = sq_ring;
	sq_ring->ring_mask = p->sq_entries - 1;
	sq_ring->ring_entries = p->sq_entries;
	ctx->sq_mask = sq_ring->ring_mask;
	ctx->sq_entries = sq_ring->ring_entries;

	size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
	if (size == SIZE_MAX)
		return -EOVERFLOW;

	ctx->sq_sqes = io_mem_alloc(size);
	if (!ctx->sq_sqes) {
		io_mem_free(ctx->sq_ring);
		return -ENOMEM;
	}

	cq_ring = io_mem_alloc(struct_size(cq_ring, cqes, p->cq_entries));
	if (!cq_ring) {
		io_mem_free(ctx->sq_ring);
		io_mem_free(ctx->sq_sqes);
		return -ENOMEM;
	}

	ctx->cq_ring = cq_ring;
	cq_ring->ring_mask = p->cq_entries - 1;
	cq_ring->ring_entries = p->cq_entries;
	ctx->cq_mask = cq_ring->ring_mask;
	ctx->cq_entries = cq_ring->ring_entries;
	return 0;
}

/*
 * Allocate an anonymous fd, this is what constitutes the application
 * visible backing of an io_uring instance. The application mmaps this
 * fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
 * we have to tie this fd to a socket for file garbage collection purposes.
 */
static int io_uring_get_fd(struct io_ring_ctx *ctx)
{
	struct file *file;
	int ret;

#if defined(CONFIG_UNIX)
	ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
				&ctx->ring_sock);
	if (ret)
		return ret;
#endif

	ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
	if (ret < 0)
		goto err;

	file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
					O_RDWR | O_CLOEXEC);
	if (IS_ERR(file)) {
		put_unused_fd(ret);
		ret = PTR_ERR(file);
		goto err;
	}

#if defined(CONFIG_UNIX)
	ctx->ring_sock->file = file;
J
Jens Axboe 已提交
2808
	ctx->ring_sock->sk->sk_user_data = ctx;
J
Jens Axboe 已提交
2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866
#endif
	fd_install(ret, file);
	return ret;
err:
#if defined(CONFIG_UNIX)
	sock_release(ctx->ring_sock);
	ctx->ring_sock = NULL;
#endif
	return ret;
}

static int io_uring_create(unsigned entries, struct io_uring_params *p)
{
	struct user_struct *user = NULL;
	struct io_ring_ctx *ctx;
	bool account_mem;
	int ret;

	if (!entries || entries > IORING_MAX_ENTRIES)
		return -EINVAL;

	/*
	 * Use twice as many entries for the CQ ring. It's possible for the
	 * application to drive a higher depth than the size of the SQ ring,
	 * since the sqes are only used at submission time. This allows for
	 * some flexibility in overcommitting a bit.
	 */
	p->sq_entries = roundup_pow_of_two(entries);
	p->cq_entries = 2 * p->sq_entries;

	user = get_uid(current_user());
	account_mem = !capable(CAP_IPC_LOCK);

	if (account_mem) {
		ret = io_account_mem(user,
				ring_pages(p->sq_entries, p->cq_entries));
		if (ret) {
			free_uid(user);
			return ret;
		}
	}

	ctx = io_ring_ctx_alloc(p);
	if (!ctx) {
		if (account_mem)
			io_unaccount_mem(user, ring_pages(p->sq_entries,
								p->cq_entries));
		free_uid(user);
		return -ENOMEM;
	}
	ctx->compat = in_compat_syscall();
	ctx->account_mem = account_mem;
	ctx->user = user;

	ret = io_allocate_scq_urings(ctx, p);
	if (ret)
		goto err;

J
Jens Axboe 已提交
2867
	ret = io_sq_offload_start(ctx, p);
J
Jens Axboe 已提交
2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914
	if (ret)
		goto err;

	ret = io_uring_get_fd(ctx);
	if (ret < 0)
		goto err;

	memset(&p->sq_off, 0, sizeof(p->sq_off));
	p->sq_off.head = offsetof(struct io_sq_ring, r.head);
	p->sq_off.tail = offsetof(struct io_sq_ring, r.tail);
	p->sq_off.ring_mask = offsetof(struct io_sq_ring, ring_mask);
	p->sq_off.ring_entries = offsetof(struct io_sq_ring, ring_entries);
	p->sq_off.flags = offsetof(struct io_sq_ring, flags);
	p->sq_off.dropped = offsetof(struct io_sq_ring, dropped);
	p->sq_off.array = offsetof(struct io_sq_ring, array);

	memset(&p->cq_off, 0, sizeof(p->cq_off));
	p->cq_off.head = offsetof(struct io_cq_ring, r.head);
	p->cq_off.tail = offsetof(struct io_cq_ring, r.tail);
	p->cq_off.ring_mask = offsetof(struct io_cq_ring, ring_mask);
	p->cq_off.ring_entries = offsetof(struct io_cq_ring, ring_entries);
	p->cq_off.overflow = offsetof(struct io_cq_ring, overflow);
	p->cq_off.cqes = offsetof(struct io_cq_ring, cqes);
	return ret;
err:
	io_ring_ctx_wait_and_kill(ctx);
	return ret;
}

/*
 * Sets up an aio uring context, and returns the fd. Applications asks for a
 * ring size, we return the actual sq/cq ring sizes (among other things) in the
 * params structure passed in.
 */
static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
{
	struct io_uring_params p;
	long ret;
	int i;

	if (copy_from_user(&p, params, sizeof(p)))
		return -EFAULT;
	for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
		if (p.resv[i])
			return -EINVAL;
	}

J
Jens Axboe 已提交
2915 2916
	if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
			IORING_SETUP_SQ_AFF))
J
Jens Axboe 已提交
2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934
		return -EINVAL;

	ret = io_uring_create(entries, &p);
	if (ret < 0)
		return ret;

	if (copy_to_user(params, &p, sizeof(p)))
		return -EFAULT;

	return ret;
}

SYSCALL_DEFINE2(io_uring_setup, u32, entries,
		struct io_uring_params __user *, params)
{
	return io_uring_setup(entries, params);
}

2935 2936
static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
			       void __user *arg, unsigned nr_args)
2937 2938
	__releases(ctx->uring_lock)
	__acquires(ctx->uring_lock)
2939 2940 2941
{
	int ret;

2942 2943 2944 2945 2946 2947 2948 2949
	/*
	 * We're inside the ring mutex, if the ref is already dying, then
	 * someone else killed the ctx or is already going through
	 * io_uring_register().
	 */
	if (percpu_ref_is_dying(&ctx->refs))
		return -ENXIO;

2950
	percpu_ref_kill(&ctx->refs);
2951 2952 2953 2954 2955 2956 2957 2958 2959

	/*
	 * Drop uring mutex before waiting for references to exit. If another
	 * thread is currently inside io_uring_enter() it might need to grab
	 * the uring_lock to make progress. If we hold it here across the drain
	 * wait, then we can deadlock. It's safe to drop the mutex here, since
	 * no new references will come in after we've killed the percpu ref.
	 */
	mutex_unlock(&ctx->uring_lock);
2960
	wait_for_completion(&ctx->ctx_done);
2961
	mutex_lock(&ctx->uring_lock);
2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972

	switch (opcode) {
	case IORING_REGISTER_BUFFERS:
		ret = io_sqe_buffer_register(ctx, arg, nr_args);
		break;
	case IORING_UNREGISTER_BUFFERS:
		ret = -EINVAL;
		if (arg || nr_args)
			break;
		ret = io_sqe_buffer_unregister(ctx);
		break;
J
Jens Axboe 已提交
2973 2974 2975 2976 2977 2978 2979 2980 2981
	case IORING_REGISTER_FILES:
		ret = io_sqe_files_register(ctx, arg, nr_args);
		break;
	case IORING_UNREGISTER_FILES:
		ret = -EINVAL;
		if (arg || nr_args)
			break;
		ret = io_sqe_files_unregister(ctx);
		break;
2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017
	default:
		ret = -EINVAL;
		break;
	}

	/* bring the ctx back to life */
	reinit_completion(&ctx->ctx_done);
	percpu_ref_reinit(&ctx->refs);
	return ret;
}

SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
		void __user *, arg, unsigned int, nr_args)
{
	struct io_ring_ctx *ctx;
	long ret = -EBADF;
	struct fd f;

	f = fdget(fd);
	if (!f.file)
		return -EBADF;

	ret = -EOPNOTSUPP;
	if (f.file->f_op != &io_uring_fops)
		goto out_fput;

	ctx = f.file->private_data;

	mutex_lock(&ctx->uring_lock);
	ret = __io_uring_register(ctx, opcode, arg, nr_args);
	mutex_unlock(&ctx->uring_lock);
out_fput:
	fdput(f);
	return ret;
}

J
Jens Axboe 已提交
3018 3019 3020 3021 3022 3023
static int __init io_uring_init(void)
{
	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
	return 0;
};
__initcall(io_uring_init);