aio.c 34.3 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
/*
 *	An async IO implementation for Linux
 *	Written by Benjamin LaHaise <bcrl@kvack.org>
 *
 *	Implements an efficient asynchronous io interface.
 *
 *	Copyright 2000, 2001, 2002 Red Hat, Inc.  All Rights Reserved.
 *
 *	See ../COPYING for licensing terms.
 */
Kent Overstreet's avatar
Kent Overstreet committed
11
12
#define pr_fmt(fmt) "%s: " fmt, __func__

Linus Torvalds's avatar
Linus Torvalds committed
13
14
15
16
17
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/aio_abi.h>
18
#include <linux/export.h>
Linus Torvalds's avatar
Linus Torvalds committed
19
#include <linux/syscalls.h>
20
#include <linux/backing-dev.h>
21
#include <linux/uio.h>
Linus Torvalds's avatar
Linus Torvalds committed
22
23
24
25
26
27

#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
28
#include <linux/mmu_context.h>
Linus Torvalds's avatar
Linus Torvalds committed
29
30
31
32
33
34
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/aio.h>
#include <linux/highmem.h>
#include <linux/workqueue.h>
#include <linux/security.h>
35
#include <linux/eventfd.h>
Jeff Moyer's avatar
Jeff Moyer committed
36
#include <linux/blkdev.h>
37
#include <linux/compat.h>
Linus Torvalds's avatar
Linus Torvalds committed
38
39
40
41

#include <asm/kmap_types.h>
#include <asm/uaccess.h>

42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
#define AIO_RING_MAGIC			0xa10a10a1
#define AIO_RING_COMPAT_FEATURES	1
#define AIO_RING_INCOMPAT_FEATURES	0
struct aio_ring {
	unsigned	id;	/* kernel internal index number */
	unsigned	nr;	/* number of io_events */
	unsigned	head;
	unsigned	tail;

	unsigned	magic;
	unsigned	compat_features;
	unsigned	incompat_features;
	unsigned	header_length;	/* size of aio_ring */


	struct io_event		io_events[0];
}; /* 128 bytes + ring size */

#define AIO_RING_PAGES	8
struct aio_ring_info {
	unsigned long		mmap_base;
	unsigned long		mmap_size;

	struct page		**ring_pages;
66
	struct mutex		ring_lock;
67
68
69
70
71
72
73
74
75
	long			nr_pages;

	unsigned		nr, tail;

	struct page		*internal_pages[AIO_RING_PAGES];
};

struct kioctx {
	atomic_t		users;
Kent Overstreet's avatar
Kent Overstreet committed
76
	atomic_t		dead;
77
78
79
80
81
82
83
84
85

	/* This needs improving */
	unsigned long		user_id;
	struct hlist_node	list;

	wait_queue_head_t	wait;

	spinlock_t		ctx_lock;

86
	atomic_t		reqs_active;
87
88
	struct list_head	active_reqs;	/* used for cancellation */

89
90
91
92
93
94
95
	/*
	 * This is what userspace passed to io_setup(), it's not used for
	 * anything but counting against the global max_reqs quota.
	 *
	 * The real limit is ring->nr - 1, which will be larger (see
	 * aio_setup_ring())
	 */
96
97
98
99
	unsigned		max_reqs;

	struct aio_ring_info	ring_info;

100
101
	spinlock_t		completion_lock;

102
	struct rcu_head		rcu_head;
Kent Overstreet's avatar
Kent Overstreet committed
103
	struct work_struct	rcu_work;
104
105
};

Linus Torvalds's avatar
Linus Torvalds committed
106
/*------ sysctl variables----*/
107
108
109
static DEFINE_SPINLOCK(aio_nr_lock);
unsigned long aio_nr;		/* current system wide number of aio requests */
unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
Linus Torvalds's avatar
Linus Torvalds committed
110
111
/*----end sysctl variables---*/

112
113
static struct kmem_cache	*kiocb_cachep;
static struct kmem_cache	*kioctx_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
114
115
116
117
118
119
120

/* aio_setup
 *	Creates the slab caches used by the aio routines, panic on
 *	failure as this is done early during the boot sequence.
 */
static int __init aio_setup(void)
{
121
122
	kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
Linus Torvalds's avatar
Linus Torvalds committed
123

Kent Overstreet's avatar
Kent Overstreet committed
124
	pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
Linus Torvalds's avatar
Linus Torvalds committed
125
126
127

	return 0;
}
128
__initcall(aio_setup);
Linus Torvalds's avatar
Linus Torvalds committed
129
130
131
132
133
134
135
136
137

static void aio_free_ring(struct kioctx *ctx)
{
	struct aio_ring_info *info = &ctx->ring_info;
	long i;

	for (i=0; i<info->nr_pages; i++)
		put_page(info->ring_pages[i]);

138
	if (info->mmap_size) {
Al Viro's avatar
Al Viro committed
139
		vm_munmap(info->mmap_base, info->mmap_size);
140
	}
Linus Torvalds's avatar
Linus Torvalds committed
141
142
143
144
145
146
147
148
149
150
151
152

	if (info->ring_pages && info->ring_pages != info->internal_pages)
		kfree(info->ring_pages);
	info->ring_pages = NULL;
	info->nr = 0;
}

static int aio_setup_ring(struct kioctx *ctx)
{
	struct aio_ring *ring;
	struct aio_ring_info *info = &ctx->ring_info;
	unsigned nr_events = ctx->max_reqs;
Zach Brown's avatar
Zach Brown committed
153
	struct mm_struct *mm = current->mm;
154
	unsigned long size, populate;
Linus Torvalds's avatar
Linus Torvalds committed
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
	int nr_pages;

	/* Compensate for the ring buffer's head/tail overlap entry */
	nr_events += 2;	/* 1 is required, 2 for good luck */

	size = sizeof(struct aio_ring);
	size += sizeof(struct io_event) * nr_events;
	nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;

	if (nr_pages < 0)
		return -EINVAL;

	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);

	info->nr = 0;
	info->ring_pages = info->internal_pages;
	if (nr_pages > AIO_RING_PAGES) {
172
		info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
173
174
175
176
177
		if (!info->ring_pages)
			return -ENOMEM;
	}

	info->mmap_size = nr_pages * PAGE_SIZE;
Kent Overstreet's avatar
Kent Overstreet committed
178
	pr_debug("attempting mmap of %lu bytes\n", info->mmap_size);
Zach Brown's avatar
Zach Brown committed
179
	down_write(&mm->mmap_sem);
180
181
	info->mmap_base = do_mmap_pgoff(NULL, 0, info->mmap_size, 
					PROT_READ|PROT_WRITE,
182
183
					MAP_ANONYMOUS|MAP_PRIVATE, 0,
					&populate);
Linus Torvalds's avatar
Linus Torvalds committed
184
	if (IS_ERR((void *)info->mmap_base)) {
Zach Brown's avatar
Zach Brown committed
185
		up_write(&mm->mmap_sem);
Linus Torvalds's avatar
Linus Torvalds committed
186
187
188
189
190
		info->mmap_size = 0;
		aio_free_ring(ctx);
		return -EAGAIN;
	}

Kent Overstreet's avatar
Kent Overstreet committed
191
	pr_debug("mmap address: 0x%08lx\n", info->mmap_base);
Zach Brown's avatar
Zach Brown committed
192
	info->nr_pages = get_user_pages(current, mm, info->mmap_base, nr_pages,
Linus Torvalds's avatar
Linus Torvalds committed
193
					1, 0, info->ring_pages, NULL);
Zach Brown's avatar
Zach Brown committed
194
	up_write(&mm->mmap_sem);
Linus Torvalds's avatar
Linus Torvalds committed
195
196
197
198
199

	if (unlikely(info->nr_pages != nr_pages)) {
		aio_free_ring(ctx);
		return -EAGAIN;
	}
200
	if (populate)
201
		mm_populate(info->mmap_base, populate);
Linus Torvalds's avatar
Linus Torvalds committed
202
203
204
205
206

	ctx->user_id = info->mmap_base;

	info->nr = nr_events;		/* trusted copy */

207
	ring = kmap_atomic(info->ring_pages[0]);
Linus Torvalds's avatar
Linus Torvalds committed
208
209
210
211
212
213
214
	ring->nr = nr_events;	/* user copy */
	ring->id = ctx->user_id;
	ring->head = ring->tail = 0;
	ring->magic = AIO_RING_MAGIC;
	ring->compat_features = AIO_RING_COMPAT_FEATURES;
	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
	ring->header_length = sizeof(struct aio_ring);
215
	kunmap_atomic(ring);
Kent Overstreet's avatar
Kent Overstreet committed
216
	flush_dcache_page(info->ring_pages[0]);
Linus Torvalds's avatar
Linus Torvalds committed
217
218
219
220
221
222
223
224

	return 0;
}

#define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
#define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
#define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)

225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
{
	struct kioctx *ctx = req->ki_ctx;
	unsigned long flags;

	spin_lock_irqsave(&ctx->ctx_lock, flags);

	if (!req->ki_list.next)
		list_add(&req->ki_list, &ctx->active_reqs);

	req->ki_cancel = cancel;

	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
}
EXPORT_SYMBOL(kiocb_set_cancel_fn);

Kent Overstreet's avatar
Kent Overstreet committed
241
242
243
static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
			struct io_event *res)
{
244
	kiocb_cancel_fn *old, *cancel;
Kent Overstreet's avatar
Kent Overstreet committed
245
246
	int ret = -EINVAL;

247
248
249
250
251
252
253
254
255
	/*
	 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
	 * actually has a cancel function, hence the cmpxchg()
	 */

	cancel = ACCESS_ONCE(kiocb->ki_cancel);
	do {
		if (!cancel || cancel == KIOCB_CANCELLED)
			return ret;
Kent Overstreet's avatar
Kent Overstreet committed
256

257
258
259
		old = cancel;
		cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
	} while (cancel != old);
Kent Overstreet's avatar
Kent Overstreet committed
260

261
262
263
264
265
266
267
268
269
	atomic_inc(&kiocb->ki_users);
	spin_unlock_irq(&ctx->ctx_lock);

	memset(res, 0, sizeof(*res));
	res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
	res->data = kiocb->ki_user_data;
	ret = cancel(kiocb, res);

	spin_lock_irq(&ctx->ctx_lock);
Kent Overstreet's avatar
Kent Overstreet committed
270
271
272
273

	return ret;
}

Kent Overstreet's avatar
Kent Overstreet committed
274
275
276
277
278
279
280
281
282
283
284
285
286
static void free_ioctx_rcu(struct rcu_head *head)
{
	struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
	kmem_cache_free(kioctx_cachep, ctx);
}

/*
 * When this function runs, the kioctx has been removed from the "hash table"
 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
 * now it's safe to cancel any that need to be.
 */
static void free_ioctx(struct kioctx *ctx)
{
287
288
	struct aio_ring_info *info = &ctx->ring_info;
	struct aio_ring *ring;
Kent Overstreet's avatar
Kent Overstreet committed
289
290
	struct io_event res;
	struct kiocb *req;
291
	unsigned head, avail;
Kent Overstreet's avatar
Kent Overstreet committed
292
293
294
295
296
297
298
299
300
301
302
303
304

	spin_lock_irq(&ctx->ctx_lock);

	while (!list_empty(&ctx->active_reqs)) {
		req = list_first_entry(&ctx->active_reqs,
				       struct kiocb, ki_list);

		list_del_init(&req->ki_list);
		kiocb_cancel(ctx, req, &res);
	}

	spin_unlock_irq(&ctx->ctx_lock);

305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
	ring = kmap_atomic(info->ring_pages[0]);
	head = ring->head;
	kunmap_atomic(ring);

	while (atomic_read(&ctx->reqs_active) > 0) {
		wait_event(ctx->wait, head != info->tail);

		avail = (head <= info->tail ? info->tail : info->nr) - head;

		atomic_sub(avail, &ctx->reqs_active);
		head += avail;
		head %= info->nr;
	}

	WARN_ON(atomic_read(&ctx->reqs_active) < 0);
Kent Overstreet's avatar
Kent Overstreet committed
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345

	aio_free_ring(ctx);

	spin_lock(&aio_nr_lock);
	BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
	aio_nr -= ctx->max_reqs;
	spin_unlock(&aio_nr_lock);

	pr_debug("freeing %p\n", ctx);

	/*
	 * Here the call_rcu() is between the wait_event() for reqs_active to
	 * hit 0, and freeing the ioctx.
	 *
	 * aio_complete() decrements reqs_active, but it has to touch the ioctx
	 * after to issue a wakeup so we use rcu.
	 */
	call_rcu(&ctx->rcu_head, free_ioctx_rcu);
}

static void put_ioctx(struct kioctx *ctx)
{
	if (unlikely(atomic_dec_and_test(&ctx->users)))
		free_ioctx(ctx);
}

Linus Torvalds's avatar
Linus Torvalds committed
346
347
348
349
350
/* ioctx_alloc
 *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
 */
static struct kioctx *ioctx_alloc(unsigned nr_events)
{
Zach Brown's avatar
Zach Brown committed
351
	struct mm_struct *mm = current->mm;
Linus Torvalds's avatar
Linus Torvalds committed
352
	struct kioctx *ctx;
353
	int err = -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
354
355
356
357
358
359
360
361

	/* Prevent overflows */
	if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
	    (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
		pr_debug("ENOMEM: nr_events too high\n");
		return ERR_PTR(-EINVAL);
	}

362
	if (!nr_events || (unsigned long)nr_events > aio_max_nr)
Linus Torvalds's avatar
Linus Torvalds committed
363
364
		return ERR_PTR(-EAGAIN);

365
	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
366
367
368
369
370
	if (!ctx)
		return ERR_PTR(-ENOMEM);

	ctx->max_reqs = nr_events;

Al Viro's avatar
Al Viro committed
371
	atomic_set(&ctx->users, 2);
Kent Overstreet's avatar
Kent Overstreet committed
372
	atomic_set(&ctx->dead, 0);
Linus Torvalds's avatar
Linus Torvalds committed
373
	spin_lock_init(&ctx->ctx_lock);
374
	spin_lock_init(&ctx->completion_lock);
375
	mutex_init(&ctx->ring_info.ring_lock);
Linus Torvalds's avatar
Linus Torvalds committed
376
377
378
379
380
381
382
383
	init_waitqueue_head(&ctx->wait);

	INIT_LIST_HEAD(&ctx->active_reqs);

	if (aio_setup_ring(ctx) < 0)
		goto out_freectx;

	/* limit the number of system wide aios */
384
	spin_lock(&aio_nr_lock);
385
386
	if (aio_nr + nr_events > aio_max_nr ||
	    aio_nr + nr_events < aio_nr) {
387
		spin_unlock(&aio_nr_lock);
Linus Torvalds's avatar
Linus Torvalds committed
388
		goto out_cleanup;
389
390
	}
	aio_nr += ctx->max_reqs;
391
	spin_unlock(&aio_nr_lock);
Linus Torvalds's avatar
Linus Torvalds committed
392

Jeff Moyer's avatar
Jeff Moyer committed
393
	/* now link into global list. */
394
395
396
	spin_lock(&mm->ioctx_lock);
	hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
	spin_unlock(&mm->ioctx_lock);
Linus Torvalds's avatar
Linus Torvalds committed
397

Kent Overstreet's avatar
Kent Overstreet committed
398
	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
Zach Brown's avatar
Zach Brown committed
399
		ctx, ctx->user_id, mm, ctx->ring_info.nr);
Linus Torvalds's avatar
Linus Torvalds committed
400
401
402
	return ctx;

out_cleanup:
403
404
	err = -EAGAIN;
	aio_free_ring(ctx);
Linus Torvalds's avatar
Linus Torvalds committed
405
406
out_freectx:
	kmem_cache_free(kioctx_cachep, ctx);
Kent Overstreet's avatar
Kent Overstreet committed
407
	pr_debug("error allocating ioctx %d\n", err);
408
	return ERR_PTR(err);
Linus Torvalds's avatar
Linus Torvalds committed
409
410
}

Kent Overstreet's avatar
Kent Overstreet committed
411
static void kill_ioctx_work(struct work_struct *work)
Linus Torvalds's avatar
Linus Torvalds committed
412
{
Kent Overstreet's avatar
Kent Overstreet committed
413
	struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
414

Kent Overstreet's avatar
Kent Overstreet committed
415
416
417
	wake_up_all(&ctx->wait);
	put_ioctx(ctx);
}
Kent Overstreet's avatar
Kent Overstreet committed
418

Kent Overstreet's avatar
Kent Overstreet committed
419
420
421
static void kill_ioctx_rcu(struct rcu_head *head)
{
	struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
Linus Torvalds's avatar
Linus Torvalds committed
422

Kent Overstreet's avatar
Kent Overstreet committed
423
424
425
	INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
	schedule_work(&ctx->rcu_work);
}
Linus Torvalds's avatar
Linus Torvalds committed
426

Kent Overstreet's avatar
Kent Overstreet committed
427
428
429
430
431
432
433
434
435
436
437
/* kill_ioctx
 *	Cancels all outstanding aio requests on an aio context.  Used
 *	when the processes owning a context have all exited to encourage
 *	the rapid destruction of the kioctx.
 */
static void kill_ioctx(struct kioctx *ctx)
{
	if (!atomic_xchg(&ctx->dead, 1)) {
		hlist_del_rcu(&ctx->list);
		/* Between hlist_del_rcu() and dropping the initial ref */
		synchronize_rcu();
438

Kent Overstreet's avatar
Kent Overstreet committed
439
440
441
442
443
444
445
446
447
		/*
		 * We can't punt to workqueue here because put_ioctx() ->
		 * free_ioctx() will unmap the ringbuffer, and that has to be
		 * done in the original process's context. kill_ioctx_rcu/work()
		 * exist for exit_aio(), as in that path free_ioctx() won't do
		 * the unmap.
		 */
		kill_ioctx_work(&ctx->rcu_work);
	}
Linus Torvalds's avatar
Linus Torvalds committed
448
449
450
451
452
}

/* wait_on_sync_kiocb:
 *	Waits on the given sync kiocb to complete.
 */
453
ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
Linus Torvalds's avatar
Linus Torvalds committed
454
{
455
	while (atomic_read(&iocb->ki_users)) {
Linus Torvalds's avatar
Linus Torvalds committed
456
		set_current_state(TASK_UNINTERRUPTIBLE);
457
		if (!atomic_read(&iocb->ki_users))
Linus Torvalds's avatar
Linus Torvalds committed
458
			break;
459
		io_schedule();
Linus Torvalds's avatar
Linus Torvalds committed
460
461
462
463
	}
	__set_current_state(TASK_RUNNING);
	return iocb->ki_user_data;
}
464
EXPORT_SYMBOL(wait_on_sync_kiocb);
Linus Torvalds's avatar
Linus Torvalds committed
465

Kent Overstreet's avatar
Kent Overstreet committed
466
467
468
469
470
471
472
/*
 * exit_aio: called when the last user of mm goes away.  At this point, there is
 * no way for any new requests to be submited or any of the io_* syscalls to be
 * called on the context.
 *
 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
 * them.
Linus Torvalds's avatar
Linus Torvalds committed
473
 */
474
void exit_aio(struct mm_struct *mm)
Linus Torvalds's avatar
Linus Torvalds committed
475
{
476
	struct kioctx *ctx;
Kent Overstreet's avatar
Kent Overstreet committed
477
	struct hlist_node *n;
478

Kent Overstreet's avatar
Kent Overstreet committed
479
	hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
Linus Torvalds's avatar
Linus Torvalds committed
480
481
482
		if (1 != atomic_read(&ctx->users))
			printk(KERN_DEBUG
				"exit_aio:ioctx still alive: %d %d %d\n",
Kent Overstreet's avatar
Kent Overstreet committed
483
484
				atomic_read(&ctx->users),
				atomic_read(&ctx->dead),
485
				atomic_read(&ctx->reqs_active));
486
487
488
489
490
491
492
493
494
		/*
		 * We don't need to bother with munmap() here -
		 * exit_mmap(mm) is coming and it'll unmap everything.
		 * Since aio_free_ring() uses non-zero ->mmap_size
		 * as indicator that it needs to unmap the area,
		 * just set it to 0; aio_free_ring() is the only
		 * place that uses ->mmap_size, so it's safe.
		 */
		ctx->ring_info.mmap_size = 0;
Kent Overstreet's avatar
Kent Overstreet committed
495
496
497
498
499

		if (!atomic_xchg(&ctx->dead, 1)) {
			hlist_del_rcu(&ctx->list);
			call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
		}
Linus Torvalds's avatar
Linus Torvalds committed
500
501
502
503
	}
}

/* aio_get_req
504
 *	Allocate a slot for an aio request.  Increments the ki_users count
Linus Torvalds's avatar
Linus Torvalds committed
505
506
507
 * of the kioctx so that the kioctx stays around until all requests are
 * complete.  Returns NULL if no requests are free.
 *
508
 * Returns with kiocb->ki_users set to 2.  The io submit code path holds
Linus Torvalds's avatar
Linus Torvalds committed
509
510
511
512
 * an extra reference while submitting the i/o.
 * This prevents races between the aio code path referencing the
 * req (after submitting it) and aio_complete() freeing the req.
 */
Kent Overstreet's avatar
Kent Overstreet committed
513
static inline struct kiocb *aio_get_req(struct kioctx *ctx)
Linus Torvalds's avatar
Linus Torvalds committed
514
{
Kent Overstreet's avatar
Kent Overstreet committed
515
516
517
518
519
520
521
	struct kiocb *req;

	if (atomic_read(&ctx->reqs_active) >= ctx->ring_info.nr)
		return NULL;

	if (atomic_inc_return(&ctx->reqs_active) > ctx->ring_info.nr - 1)
		goto out_put;
Linus Torvalds's avatar
Linus Torvalds committed
522

523
	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
Linus Torvalds's avatar
Linus Torvalds committed
524
	if (unlikely(!req))
Kent Overstreet's avatar
Kent Overstreet committed
525
		goto out_put;
Linus Torvalds's avatar
Linus Torvalds committed
526

527
	atomic_set(&req->ki_users, 2);
Linus Torvalds's avatar
Linus Torvalds committed
528
529
	req->ki_ctx = ctx;

Jeff Moyer's avatar
Jeff Moyer committed
530
	return req;
Kent Overstreet's avatar
Kent Overstreet committed
531
532
533
out_put:
	atomic_dec(&ctx->reqs_active);
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
534
535
}

536
static void kiocb_free(struct kiocb *req)
Linus Torvalds's avatar
Linus Torvalds committed
537
{
538
539
	if (req->ki_filp)
		fput(req->ki_filp);
540
541
	if (req->ki_eventfd != NULL)
		eventfd_ctx_put(req->ki_eventfd);
Linus Torvalds's avatar
Linus Torvalds committed
542
543
	if (req->ki_dtor)
		req->ki_dtor(req);
544
545
	if (req->ki_iovec != &req->ki_inline_vec)
		kfree(req->ki_iovec);
Linus Torvalds's avatar
Linus Torvalds committed
546
547
548
	kmem_cache_free(kiocb_cachep, req);
}

549
void aio_put_req(struct kiocb *req)
Linus Torvalds's avatar
Linus Torvalds committed
550
{
551
552
	if (atomic_dec_and_test(&req->ki_users))
		kiocb_free(req);
Linus Torvalds's avatar
Linus Torvalds committed
553
}
554
EXPORT_SYMBOL(aio_put_req);
Linus Torvalds's avatar
Linus Torvalds committed
555

556
static struct kioctx *lookup_ioctx(unsigned long ctx_id)
Linus Torvalds's avatar
Linus Torvalds committed
557
{
558
	struct mm_struct *mm = current->mm;
559
	struct kioctx *ctx, *ret = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
560

561
562
	rcu_read_lock();

563
	hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
Kent Overstreet's avatar
Kent Overstreet committed
564
565
		if (ctx->user_id == ctx_id) {
			atomic_inc(&ctx->users);
566
			ret = ctx;
Linus Torvalds's avatar
Linus Torvalds committed
567
568
			break;
		}
569
	}
Linus Torvalds's avatar
Linus Torvalds committed
570

571
	rcu_read_unlock();
572
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
573
574
575
576
577
}

/* aio_complete
 *	Called when the io request on the given iocb is complete.
 */
578
void aio_complete(struct kiocb *iocb, long res, long res2)
Linus Torvalds's avatar
Linus Torvalds committed
579
580
581
582
{
	struct kioctx	*ctx = iocb->ki_ctx;
	struct aio_ring_info	*info;
	struct aio_ring	*ring;
Kent Overstreet's avatar
Kent Overstreet committed
583
	struct io_event	*ev_page, *event;
Linus Torvalds's avatar
Linus Torvalds committed
584
	unsigned long	flags;
Kent Overstreet's avatar
Kent Overstreet committed
585
	unsigned tail, pos;
Linus Torvalds's avatar
Linus Torvalds committed
586

587
588
589
590
591
592
	/*
	 * Special case handling for sync iocbs:
	 *  - events go directly into the iocb for fast handling
	 *  - the sync task with the iocb in its stack holds the single iocb
	 *    ref, no other paths have a way to get another ref
	 *  - the sync task helpfully left a reference to itself in the iocb
Linus Torvalds's avatar
Linus Torvalds committed
593
594
	 */
	if (is_sync_kiocb(iocb)) {
595
		BUG_ON(atomic_read(&iocb->ki_users) != 1);
Linus Torvalds's avatar
Linus Torvalds committed
596
		iocb->ki_user_data = res;
597
		atomic_set(&iocb->ki_users, 0);
Linus Torvalds's avatar
Linus Torvalds committed
598
		wake_up_process(iocb->ki_obj.tsk);
599
		return;
Linus Torvalds's avatar
Linus Torvalds committed
600
601
602
603
	}

	info = &ctx->ring_info;

Kent Overstreet's avatar
Kent Overstreet committed
604
605
606
	/*
	 * Take rcu_read_lock() in case the kioctx is being destroyed, as we
	 * need to issue a wakeup after decrementing reqs_active.
Linus Torvalds's avatar
Linus Torvalds committed
607
	 */
Kent Overstreet's avatar
Kent Overstreet committed
608
	rcu_read_lock();
Linus Torvalds's avatar
Linus Torvalds committed
609

610
611
612
613
614
615
616
	if (iocb->ki_list.next) {
		unsigned long flags;

		spin_lock_irqsave(&ctx->ctx_lock, flags);
		list_del(&iocb->ki_list);
		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
	}
617

Linus Torvalds's avatar
Linus Torvalds committed
618
619
620
621
	/*
	 * cancelled requests don't get events, userland was given one
	 * when the event got cancelled.
	 */
622
	if (unlikely(xchg(&iocb->ki_cancel,
623
624
625
			  KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
		atomic_dec(&ctx->reqs_active);
		/* Still need the wake_up in case free_ioctx is waiting */
Linus Torvalds's avatar
Linus Torvalds committed
626
		goto put_rq;
627
	}
Linus Torvalds's avatar
Linus Torvalds committed
628

629
630
631
632
633
634
635
	/*
	 * Add a completion event to the ring buffer. Must be done holding
	 * ctx->ctx_lock to prevent other code from messing with the tail
	 * pointer since we might be called from irq context.
	 */
	spin_lock_irqsave(&ctx->completion_lock, flags);

Linus Torvalds's avatar
Linus Torvalds committed
636
	tail = info->tail;
Kent Overstreet's avatar
Kent Overstreet committed
637
638
	pos = tail + AIO_EVENTS_OFFSET;

639
640
	if (++tail >= info->nr)
		tail = 0;
Linus Torvalds's avatar
Linus Torvalds committed
641

Kent Overstreet's avatar
Kent Overstreet committed
642
643
644
	ev_page = kmap_atomic(info->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
	event = ev_page + pos % AIO_EVENTS_PER_PAGE;

Linus Torvalds's avatar
Linus Torvalds committed
645
646
647
648
649
	event->obj = (u64)(unsigned long)iocb->ki_obj.user;
	event->data = iocb->ki_user_data;
	event->res = res;
	event->res2 = res2;

Kent Overstreet's avatar
Kent Overstreet committed
650
651
652
653
	kunmap_atomic(ev_page);
	flush_dcache_page(info->ring_pages[pos / AIO_EVENTS_PER_PAGE]);

	pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
Kent Overstreet's avatar
Kent Overstreet committed
654
655
		 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
		 res, res2);
Linus Torvalds's avatar
Linus Torvalds committed
656
657
658
659
660
661
662
663

	/* after flagging the request as done, we
	 * must never even look at it again
	 */
	smp_wmb();	/* make event visible before updating tail */

	info->tail = tail;

Kent Overstreet's avatar
Kent Overstreet committed
664
665
	ring = kmap_atomic(info->ring_pages[0]);
	ring->tail = tail;
666
	kunmap_atomic(ring);
Kent Overstreet's avatar
Kent Overstreet committed
667
	flush_dcache_page(info->ring_pages[0]);
Linus Torvalds's avatar
Linus Torvalds committed
668

669
670
	spin_unlock_irqrestore(&ctx->completion_lock, flags);

Kent Overstreet's avatar
Kent Overstreet committed
671
	pr_debug("added to ring %p at [%u]\n", iocb, tail);
Davide Libenzi's avatar
Davide Libenzi committed
672
673
674
675
676
677

	/*
	 * Check if the user asked us to deliver the result through an
	 * eventfd. The eventfd_signal() function is safe to be called
	 * from IRQ context.
	 */
678
	if (iocb->ki_eventfd != NULL)
Davide Libenzi's avatar
Davide Libenzi committed
679
680
		eventfd_signal(iocb->ki_eventfd, 1);

Linus Torvalds's avatar
Linus Torvalds committed
681
682
put_rq:
	/* everything turned out well, dispose of the aiocb. */
683
	aio_put_req(iocb);
Linus Torvalds's avatar
Linus Torvalds committed
684

685
686
687
688
689
690
691
692
	/*
	 * We have to order our ring_info tail store above and test
	 * of the wait list below outside the wait lock.  This is
	 * like in wake_up_bit() where clearing a bit has to be
	 * ordered with the unlocked test.
	 */
	smp_mb();

Linus Torvalds's avatar
Linus Torvalds committed
693
694
695
	if (waitqueue_active(&ctx->wait))
		wake_up(&ctx->wait);

Kent Overstreet's avatar
Kent Overstreet committed
696
	rcu_read_unlock();
Linus Torvalds's avatar
Linus Torvalds committed
697
}
698
EXPORT_SYMBOL(aio_complete);
Linus Torvalds's avatar
Linus Torvalds committed
699

700
701
702
/* aio_read_events
 *	Pull an event off of the ioctx's event ring.  Returns the number of
 *	events fetched
Linus Torvalds's avatar
Linus Torvalds committed
703
 */
704
705
static long aio_read_events_ring(struct kioctx *ctx,
				 struct io_event __user *event, long nr)
Linus Torvalds's avatar
Linus Torvalds committed
706
{
707
	struct aio_ring_info *info = &ctx->ring_info;
Linus Torvalds's avatar
Linus Torvalds committed
708
	struct aio_ring *ring;
709
710
711
712
713
	unsigned head, pos;
	long ret = 0;
	int copy_ret;

	mutex_lock(&info->ring_lock);
Linus Torvalds's avatar
Linus Torvalds committed
714

715
	ring = kmap_atomic(info->ring_pages[0]);
716
717
718
719
	head = ring->head;
	kunmap_atomic(ring);

	pr_debug("h%u t%u m%u\n", head, info->tail, info->nr);
Linus Torvalds's avatar
Linus Torvalds committed
720

721
	if (head == info->tail)
Linus Torvalds's avatar
Linus Torvalds committed
722
723
		goto out;

724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
	while (ret < nr) {
		long avail;
		struct io_event *ev;
		struct page *page;

		avail = (head <= info->tail ? info->tail : info->nr) - head;
		if (head == info->tail)
			break;

		avail = min(avail, nr - ret);
		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
			    ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));

		pos = head + AIO_EVENTS_OFFSET;
		page = info->ring_pages[pos / AIO_EVENTS_PER_PAGE];
		pos %= AIO_EVENTS_PER_PAGE;

		ev = kmap(page);
		copy_ret = copy_to_user(event + ret, ev + pos,
					sizeof(*ev) * avail);
		kunmap(page);

		if (unlikely(copy_ret)) {
			ret = -EFAULT;
			goto out;
		}

		ret += avail;
		head += avail;
		head %= info->nr;
Linus Torvalds's avatar
Linus Torvalds committed
754
755
	}

756
757
	ring = kmap_atomic(info->ring_pages[0]);
	ring->head = head;
758
	kunmap_atomic(ring);
Kent Overstreet's avatar
Kent Overstreet committed
759
	flush_dcache_page(info->ring_pages[0]);
760
761

	pr_debug("%li  h%u t%u\n", ret, head, info->tail);
762
763

	atomic_sub(ret, &ctx->reqs_active);
764
765
766
out:
	mutex_unlock(&info->ring_lock);

Linus Torvalds's avatar
Linus Torvalds committed
767
768
769
	return ret;
}

770
771
static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
			    struct io_event __user *event, long *i)
Linus Torvalds's avatar
Linus Torvalds committed
772
{
773
	long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
Linus Torvalds's avatar
Linus Torvalds committed
774

775
776
	if (ret > 0)
		*i += ret;
Linus Torvalds's avatar
Linus Torvalds committed
777

778
779
	if (unlikely(atomic_read(&ctx->dead)))
		ret = -EINVAL;
Linus Torvalds's avatar
Linus Torvalds committed
780

781
782
	if (!*i)
		*i = ret;
Linus Torvalds's avatar
Linus Torvalds committed
783

784
	return ret < 0 || *i >= min_nr;
Linus Torvalds's avatar
Linus Torvalds committed
785
786
}

787
static long read_events(struct kioctx *ctx, long min_nr, long nr,
Linus Torvalds's avatar
Linus Torvalds committed
788
789
790
			struct io_event __user *event,
			struct timespec __user *timeout)
{
791
792
	ktime_t until = { .tv64 = KTIME_MAX };
	long ret = 0;
Linus Torvalds's avatar
Linus Torvalds committed
793
794
795

	if (timeout) {
		struct timespec	ts;
796

Linus Torvalds's avatar
Linus Torvalds committed
797
		if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
798
			return -EFAULT;
Linus Torvalds's avatar
Linus Torvalds committed
799

800
		until = timespec_to_ktime(ts);
Linus Torvalds's avatar
Linus Torvalds committed
801
802
	}

803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
	/*
	 * Note that aio_read_events() is being called as the conditional - i.e.
	 * we're calling it after prepare_to_wait() has set task state to
	 * TASK_INTERRUPTIBLE.
	 *
	 * But aio_read_events() can block, and if it blocks it's going to flip
	 * the task state back to TASK_RUNNING.
	 *
	 * This should be ok, provided it doesn't flip the state back to
	 * TASK_RUNNING and return 0 too much - that causes us to spin. That
	 * will only happen if the mutex_lock() call blocks, and we then find
	 * the ringbuffer empty. So in practice we should be ok, but it's
	 * something to be aware of when touching this code.
	 */
	wait_event_interruptible_hrtimeout(ctx->wait,
			aio_read_events(ctx, min_nr, nr, event, &ret), until);
Linus Torvalds's avatar
Linus Torvalds committed
819

820
821
	if (!ret && signal_pending(current))
		ret = -EINTR;
Linus Torvalds's avatar
Linus Torvalds committed
822

823
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
}

/* sys_io_setup:
 *	Create an aio_context capable of receiving at least nr_events.
 *	ctxp must not point to an aio_context that already exists, and
 *	must be initialized to 0 prior to the call.  On successful
 *	creation of the aio_context, *ctxp is filled in with the resulting 
 *	handle.  May fail with -EINVAL if *ctxp is not initialized,
 *	if the specified nr_events exceeds internal limits.  May fail 
 *	with -EAGAIN if the specified nr_events exceeds the user's limit 
 *	of available events.  May fail with -ENOMEM if insufficient kernel
 *	resources are available.  May fail with -EFAULT if an invalid
 *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
 *	implemented.
 */
839
SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
Linus Torvalds's avatar
Linus Torvalds committed
840
841
842
843
844
845
846
847
848
849
{
	struct kioctx *ioctx = NULL;
	unsigned long ctx;
	long ret;

	ret = get_user(ctx, ctxp);
	if (unlikely(ret))
		goto out;

	ret = -EINVAL;
850
851
852
	if (unlikely(ctx || nr_events == 0)) {
		pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
		         ctx, nr_events);
Linus Torvalds's avatar
Linus Torvalds committed
853
854
855
856
857
858
859
		goto out;
	}

	ioctx = ioctx_alloc(nr_events);
	ret = PTR_ERR(ioctx);
	if (!IS_ERR(ioctx)) {
		ret = put_user(ioctx->user_id, ctxp);
860
		if (ret)
Kent Overstreet's avatar
Kent Overstreet committed
861
			kill_ioctx(ioctx);
862
		put_ioctx(ioctx);
Linus Torvalds's avatar
Linus Torvalds committed
863
864
865
866
867
868
869
870
871
	}

out:
	return ret;
}

/* sys_io_destroy:
 *	Destroy the aio_context specified.  May cancel any outstanding 
 *	AIOs and block on completion.  Will fail with -ENOSYS if not
872
 *	implemented.  May fail with -EINVAL if the context pointed to
Linus Torvalds's avatar
Linus Torvalds committed
873
874
 *	is invalid.
 */
875
SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
Linus Torvalds's avatar
Linus Torvalds committed
876
877
878
{
	struct kioctx *ioctx = lookup_ioctx(ctx);
	if (likely(NULL != ioctx)) {
Kent Overstreet's avatar
Kent Overstreet committed
879
		kill_ioctx(ioctx);
880
		put_ioctx(ioctx);
Linus Torvalds's avatar
Linus Torvalds committed
881
882
883
884
885
886
		return 0;
	}
	pr_debug("EINVAL: io_destroy: invalid context id\n");
	return -EINVAL;
}

887
static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
Linus Torvalds's avatar
Linus Torvalds committed
888
{
889
890
891
892
893
894
895
896
897
898
899
900
901
	struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];

	BUG_ON(ret <= 0);

	while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
		ssize_t this = min((ssize_t)iov->iov_len, ret);
		iov->iov_base += this;
		iov->iov_len -= this;
		iocb->ki_left -= this;
		ret -= this;
		if (iov->iov_len == 0) {
			iocb->ki_cur_seg++;
			iov++;
902
		}
903
	}
Linus Torvalds's avatar
Linus Torvalds committed
904

905
906
907
	/* the caller should not have done more io than what fit in
	 * the remaining iovecs */
	BUG_ON(ret > 0 && iocb->ki_left == 0);
Linus Torvalds's avatar
Linus Torvalds committed
908
909
}

910
static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
Linus Torvalds's avatar
Linus Torvalds committed
911
912
{
	struct file *file = iocb->ki_filp;
913
914
915
916
	struct address_space *mapping = file->f_mapping;
	struct inode *inode = mapping->host;
	ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
			 unsigned long, loff_t);
Linus Torvalds's avatar
Linus Torvalds committed
917
	ssize_t ret = 0;
918
919
920
921
922
923
924
925
926
927
	unsigned short opcode;

	if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
		(iocb->ki_opcode == IOCB_CMD_PREAD)) {
		rw_op = file->f_op->aio_read;
		opcode = IOCB_CMD_PREADV;
	} else {
		rw_op = file->f_op->aio_write;
		opcode = IOCB_CMD_PWRITEV;
	}
Linus Torvalds's avatar
Linus Torvalds committed
928

929
930
931
932
	/* This matches the pread()/pwrite() logic */
	if (iocb->ki_pos < 0)
		return -EINVAL;

933
934
	if (opcode == IOCB_CMD_PWRITEV)
		file_start_write(file);
935
	do {
936
937
938
939
940
941
942
943
944
945
946
		ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
			    iocb->ki_nr_segs - iocb->ki_cur_seg,
			    iocb->ki_pos);
		if (ret > 0)
			aio_advance_iovec(iocb, ret);

	/* retry all partial writes.  retry partial reads as long as its a
	 * regular file. */
	} while (ret > 0 && iocb->ki_left > 0 &&
		 (opcode == IOCB_CMD_PWRITEV ||
		  (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
947
948
	if (opcode == IOCB_CMD_PWRITEV)
		file_end_write(file);
Linus Torvalds's avatar
Linus Torvalds committed
949

950
951
	/* This means we must have transferred all that we could */
	/* No need to retry anymore */
Linus Torvalds's avatar
Linus Torvalds committed
952
953
954
	if ((ret == 0) || (iocb->ki_left == 0))
		ret = iocb->ki_nbytes - iocb->ki_left;

955
956
957
	/* If we managed to write some out we return that, rather than
	 * the eventual error. */
	if (opcode == IOCB_CMD_PWRITEV
Zach Brown's avatar
Zach Brown committed
958
	    && ret < 0 && ret != -EIOCBQUEUED
959
960
961
	    && iocb->ki_nbytes - iocb->ki_left)
		ret = iocb->ki_nbytes - iocb->ki_left;

Linus Torvalds's avatar
Linus Torvalds committed
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
	return ret;
}

static ssize_t aio_fdsync(struct kiocb *iocb)
{
	struct file *file = iocb->ki_filp;
	ssize_t ret = -EINVAL;

	if (file->f_op->aio_fsync)
		ret = file->f_op->aio_fsync(iocb, 1);
	return ret;
}

static ssize_t aio_fsync(struct kiocb *iocb)
{
	struct file *file = iocb->ki_filp;
	ssize_t ret = -EINVAL;

	if (file->f_op->aio_fsync)
		ret = file->f_op->aio_fsync(iocb, 0);
	return ret;
}

985
static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
986
987
988
{
	ssize_t ret;

989
990
991
992
993
#ifdef CONFIG_COMPAT
	if (compat)
		ret = compat_rw_copy_check_uvector(type,
				(struct compat_iovec __user *)kiocb->ki_buf,
				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
994
				&kiocb->ki_iovec);
995
996
997
998
999
	else
#endif
		ret = rw_copy_check_uvector(type,
				(struct iovec __user *)kiocb->ki_buf,
				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
1000
				&kiocb->ki_iovec);
1001
1002
1003
	if (ret < 0)
		goto out;

1004
1005
1006
1007
	ret = rw_verify_area(type, kiocb->ki_filp, &kiocb->ki_pos, ret);
	if (ret < 0)
		goto out;

1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
	kiocb->ki_nr_segs = kiocb->ki_nbytes;
	kiocb->ki_cur_seg = 0;
	/* ki_nbytes/left now reflect bytes instead of segs */
	kiocb->ki_nbytes = ret;
	kiocb->ki_left = ret;

	ret = 0;
out:
	return ret;
}

1019
static ssize_t aio_setup_single_vector(int type, struct file * file, struct kiocb *kiocb)
1020
{
1021
1022
1023
1024
1025
1026
	int bytes;

	bytes = rw_verify_area(type, file, &kiocb->ki_pos, kiocb->ki_left);
	if (bytes < 0)
		return bytes;

1027
1028
	kiocb->ki_iovec = &kiocb->ki_inline_vec;
	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
1029
	kiocb->ki_iovec->iov_len = bytes;
1030
1031
1032
1033
1034
	kiocb->ki_nr_segs = 1;
	kiocb->ki_cur_seg = 0;
	return 0;
}

Linus Torvalds's avatar
Linus Torvalds committed
1035
1036
1037
1038
1039
/*
 * aio_setup_iocb:
 *	Performs the initial checks and aio retry method
 *	setup for the kiocb at the time of io submission.
 */
1040
static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
Linus Torvalds's avatar
Linus Torvalds committed
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
{
	struct file *file = kiocb->ki_filp;
	ssize_t ret = 0;

	switch (kiocb->ki_opcode) {
	case IOCB_CMD_PREAD:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_READ)))
			break;
		ret = -EFAULT;
		if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
			kiocb->ki_left)))
			break;
1054
		ret = aio_setup_single_vector(READ, file, kiocb);
1055
1056
		if (ret)
			break;
Linus Torvalds's avatar
Linus Torvalds committed
1057
1058
		ret = -EINVAL;
		if (file->f_op->aio_read)
1059
			kiocb->ki_retry = aio_rw_vect_retry;
Linus Torvalds's avatar
Linus Torvalds committed
1060
1061
1062
1063
1064
1065
1066
1067
1068
		break;
	case IOCB_CMD_PWRITE:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_WRITE)))
			break;
		ret = -EFAULT;
		if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
			kiocb->ki_left)))
			break;
1069
		ret = aio_setup_single_vector(WRITE, file, kiocb);
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
		if (ret)
			break;
		ret = -EINVAL;
		if (file->f_op->aio_write)
			kiocb->ki_retry = aio_rw_vect_retry;
		break;
	case IOCB_CMD_PREADV:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_READ)))
			break;
1080
		ret = aio_setup_vectored_rw(READ, kiocb, compat);
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
		if (ret)
			break;
		ret = -EINVAL;
		if (file->f_op->aio_read)
			kiocb->ki_retry = aio_rw_vect_retry;
		break;
	case IOCB_CMD_PWRITEV:
		ret = -EBADF;
		if (unlikely(!(file->f_mode & FMODE_WRITE)))
			break;
1091
		ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
1092
1093
		if (ret)
			break;
Linus Torvalds's avatar
Linus Torvalds committed
1094
1095
		ret = -EINVAL;
		if (file->f_op->aio_write)
1096
			kiocb->ki_retry = aio_rw_vect_retry;
Linus Torvalds's avatar
Linus Torvalds committed
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
		break;
	case IOCB_CMD_FDSYNC:
		ret = -EINVAL;
		if (file->f_op->aio_fsync)
			kiocb->ki_retry = aio_fdsync;
		break;
	case IOCB_CMD_FSYNC:
		ret = -EINVAL;
		if (file->f_op->aio_fsync)
			kiocb->ki_retry = aio_fsync;
		break;
	default:
Kent Overstreet's avatar
Kent Overstreet committed
1109
		pr_debug("EINVAL: no operation provided\n");
Linus Torvalds's avatar
Linus Torvalds committed
1110
1111
1112
1113
1114
1115
1116
1117
1118
		ret = -EINVAL;
	}

	if (!kiocb->ki_retry)
		return ret;

	return 0;
}

1119
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
Kent Overstreet's avatar
Kent Overstreet committed
1120
			 struct iocb *iocb, bool compat)
Linus Torvalds's avatar
Linus Torvalds committed
1121
1122
1123
1124
1125
{
	struct kiocb *req;
	ssize_t ret;

	/* enforce forwards compatibility on users */
1126
	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
Kent Overstreet's avatar
Kent Overstreet committed
1127
		pr_debug("EINVAL: reserve field set\n");
Linus Torvalds's avatar
Linus Torvalds committed
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
		return -EINVAL;
	}

	/* prevent overflows */
	if (unlikely(
	    (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
	    (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
	    ((ssize_t)iocb->aio_nbytes < 0)
	   )) {
		pr_debug("EINVAL: io_submit: overflow check\n");
		return -EINVAL;
	}

Kent Overstreet's avatar
Kent Overstreet committed
1141
	req = aio_get_req(ctx);  /* returns with 2 references to req */
1142
	if (unlikely(!req))
Linus Torvalds's avatar
Linus Torvalds committed
1143
		return -EAGAIN;
1144
1145
1146
1147
1148

	req->ki_filp = fget(iocb->aio_fildes);
	if (unlikely(!req->ki_filp)) {
		ret = -EBADF;
		goto out_put_req;
Linus Torvalds's avatar
Linus Torvalds committed
1149
	}
1150

1151
1152
1153
1154
1155
1156
1157
	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
		/*
		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
		 * instance of the file* now. The file descriptor must be
		 * an eventfd() fd, and will be signaled for each completed
		 * event using the eventfd_signal() function.
		 */
1158
		req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1159
		if (IS_ERR(req->ki_eventfd)) {
1160
			ret = PTR_ERR(req->ki_eventfd);
1161
			req->ki_eventfd = NULL;
1162
1163
1164
			goto out_put_req;
		}
	}
Linus Torvalds's avatar
Linus Torvalds committed
1165

1166
	ret = put_user(req->ki_key, &user_iocb->aio_key);
Linus Torvalds's avatar
Linus Torvalds committed
1167
	if (unlikely(ret)) {
Kent Overstreet's avatar
Kent Overstreet committed
1168
		pr_debug("EFAULT: aio_key\n");
Linus Torvalds's avatar
Linus Torvalds committed
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
		goto out_put_req;
	}

	req->ki_obj.user = user_iocb;
	req->ki_user_data = iocb->aio_data;
	req->ki_pos = iocb->aio_offset;

	req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
	req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
	req->ki_opcode = iocb->aio_lio_opcode;

1180
	ret = aio_setup_iocb(req, compat);
Zach Brown's avatar
Zach Brown committed
1181
	if (ret)
1182
		goto out_put_req;
Zach Brown's avatar
Zach Brown committed
1183

1184
	ret = req->ki_retry(req);
Zach Brown's avatar
Zach Brown committed
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
	if (ret != -EIOCBQUEUED) {
		/*
		 * There's no easy way to restart the syscall since other AIO's
		 * may be already running. Just fail this IO with EINTR.
		 */
		if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
			     ret == -ERESTARTNOHAND ||
			     ret == -ERESTART_RESTARTBLOCK))
			ret = -EINTR;
		aio_complete(req, ret, 0);
1195
	}
Jeff Moyer's avatar
Jeff Moyer committed
1196

Linus Torvalds's avatar
Linus Torvalds committed
1197
1198
1199
1200
	aio_put_req(req);	/* drop extra ref to req */
	return 0;

out_put_req:
1201
	atomic_dec(&ctx->reqs_active);
Linus Torvalds's avatar
Linus Torvalds committed
1202
1203
1204
1205
1206
	aio_put_req(req);	/* drop extra ref to req */
	aio_put_req(req);	/* drop i/o ref to req */
	return ret;
}

1207
1208
long do_io_submit(aio_context_t ctx_id, long nr,
		  struct iocb __user *__user *iocbpp, bool compat)
Linus Torvalds's avatar
Linus Torvalds committed
1209
1210
1211
{
	struct kioctx *ctx;
	long ret = 0;
Jeff Moyer's avatar
Jeff Moyer committed
1212
	int i = 0;
Shaohua Li's avatar
Shaohua Li committed
1213
	struct blk_plug plug;
Linus Torvalds's avatar
Linus Torvalds committed
1214
1215
1216
1217

	if (unlikely(nr < 0))
		return -EINVAL;

1218
1219
1220
	if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
		nr = LONG_MAX/sizeof(*iocbpp);

Linus Torvalds's avatar
Linus Torvalds committed
1221
1222
1223
1224
1225
	if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
		return -EFAULT;

	ctx = lookup_ioctx(ctx_id);
	if (unlikely(!ctx)) {
Kent Overstreet's avatar
Kent Overstreet committed
1226
		pr_debug("EINVAL: invalid context id\n");
Linus Torvalds's avatar
Linus Torvalds committed
1227
1228
1229
		return -EINVAL;
	}

Shaohua Li's avatar
Shaohua Li committed
1230
1231
	blk_start_plug(&plug);

Linus Torvalds's avatar
Linus Torvalds committed
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
	/*
	 * AKPM: should this return a partial result if some of the IOs were
	 * successfully submitted?
	 */
	for (i=0; i<nr; i++) {
		struct iocb __user *user_iocb;
		struct iocb tmp;

		if (unlikely(__get_user(user_iocb, iocbpp + i))) {
			ret = -EFAULT;
			break;
		}

		if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
			ret = -EFAULT;
			break;
		}

Kent Overstreet's avatar
Kent Overstreet committed
1250
		ret = io_submit_one(ctx, user_iocb, &tmp, compat);
Linus Torvalds's avatar
Linus Torvalds committed
1251
1252
1253
		if (ret)
			break;
	}
Shaohua Li's avatar
Shaohua Li committed
1254
	blk_finish_plug(&plug);
Linus Torvalds's avatar
Linus Torvalds committed
1255
1256
1257
1258
1259

	put_ioctx(ctx);
	return i ? i : ret;
}

1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
/* sys_io_submit:
 *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
 *	the number of iocbs queued.  May return -EINVAL if the aio_context
 *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
 *	*iocbpp[0] is not properly initialized, if the operation specified
 *	is invalid for the file descriptor in the iocb.  May fail with
 *	-EFAULT if any of the data structures point to invalid data.  May
 *	fail with -EBADF if the file descriptor specified in the first
 *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
 *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
 *	fail with -ENOSYS if not implemented.
 */
SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
		struct iocb __user * __user *, iocbpp)
{
	return do_io_submit(ctx_id, nr, iocbpp, 0);
}

Linus Torvalds's avatar
Linus Torvalds committed
1278
1279
1280
/* lookup_kiocb
 *	Finds a given iocb for cancellation.
 */
1281
1282
static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
				  u32 key)
Linus Torvalds's avatar
Linus Torvalds committed
1283
1284
{
	struct list_head *pos;
1285
1286
1287

	assert_spin_locked(&ctx->ctx_lock);

Linus Torvalds's avatar
Linus Torvalds committed