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1 /*
2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
4 *
5 * Implements an efficient asynchronous io interface.
6 *
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8 *
9 * See ../COPYING for licensing terms.
10 */
11 #define pr_fmt(fmt) "%s: " fmt, __func__
12
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/errno.h>
16 #include <linux/time.h>
17 #include <linux/aio_abi.h>
18 #include <linux/export.h>
19 #include <linux/syscalls.h>
20 #include <linux/backing-dev.h>
21 #include <linux/uio.h>
22
23 #include <linux/sched.h>
24 #include <linux/fs.h>
25 #include <linux/file.h>
26 #include <linux/mm.h>
27 #include <linux/mman.h>
28 #include <linux/mmu_context.h>
29 #include <linux/percpu.h>
30 #include <linux/slab.h>
31 #include <linux/timer.h>
32 #include <linux/aio.h>
33 #include <linux/highmem.h>
34 #include <linux/workqueue.h>
35 #include <linux/security.h>
36 #include <linux/eventfd.h>
37 #include <linux/blkdev.h>
38 #include <linux/compat.h>
39 #include <linux/migrate.h>
40 #include <linux/ramfs.h>
41 #include <linux/percpu-refcount.h>
42 #include <linux/mount.h>
43
44 #include <asm/kmap_types.h>
45 #include <asm/uaccess.h>
46
47 #include "internal.h"
48
49 #define AIO_RING_MAGIC 0xa10a10a1
50 #define AIO_RING_COMPAT_FEATURES 1
51 #define AIO_RING_INCOMPAT_FEATURES 0
52 struct aio_ring {
53 unsigned id; /* kernel internal index number */
54 unsigned nr; /* number of io_events */
55 unsigned head; /* Written to by userland or under ring_lock
56 * mutex by aio_read_events_ring(). */
57 unsigned tail;
58
59 unsigned magic;
60 unsigned compat_features;
61 unsigned incompat_features;
62 unsigned header_length; /* size of aio_ring */
63
64
65 struct io_event io_events[0];
66 }; /* 128 bytes + ring size */
67
68 #define AIO_RING_PAGES 8
69
70 struct kioctx_table {
71 struct rcu_head rcu;
72 unsigned nr;
73 struct kioctx *table[];
74 };
75
76 struct kioctx_cpu {
77 unsigned reqs_available;
78 };
79
80 struct ctx_rq_wait {
81 struct completion comp;
82 atomic_t count;
83 };
84
85 struct kioctx {
86 struct percpu_ref users;
87 atomic_t dead;
88
89 struct percpu_ref reqs;
90
91 unsigned long user_id;
92
93 struct __percpu kioctx_cpu *cpu;
94
95 /*
96 * For percpu reqs_available, number of slots we move to/from global
97 * counter at a time:
98 */
99 unsigned req_batch;
100 /*
101 * This is what userspace passed to io_setup(), it's not used for
102 * anything but counting against the global max_reqs quota.
103 *
104 * The real limit is nr_events - 1, which will be larger (see
105 * aio_setup_ring())
106 */
107 unsigned max_reqs;
108
109 /* Size of ringbuffer, in units of struct io_event */
110 unsigned nr_events;
111
112 unsigned long mmap_base;
113 unsigned long mmap_size;
114
115 struct page **ring_pages;
116 long nr_pages;
117
118 struct work_struct free_work;
119
120 /*
121 * signals when all in-flight requests are done
122 */
123 struct ctx_rq_wait *rq_wait;
124
125 struct {
126 /*
127 * This counts the number of available slots in the ringbuffer,
128 * so we avoid overflowing it: it's decremented (if positive)
129 * when allocating a kiocb and incremented when the resulting
130 * io_event is pulled off the ringbuffer.
131 *
132 * We batch accesses to it with a percpu version.
133 */
134 atomic_t reqs_available;
135 } ____cacheline_aligned_in_smp;
136
137 struct {
138 spinlock_t ctx_lock;
139 struct list_head active_reqs; /* used for cancellation */
140 } ____cacheline_aligned_in_smp;
141
142 struct {
143 struct mutex ring_lock;
144 wait_queue_head_t wait;
145 } ____cacheline_aligned_in_smp;
146
147 struct {
148 unsigned tail;
149 unsigned completed_events;
150 spinlock_t completion_lock;
151 } ____cacheline_aligned_in_smp;
152
153 struct page *internal_pages[AIO_RING_PAGES];
154 struct file *aio_ring_file;
155
156 unsigned id;
157 };
158
159 /*
160 * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
161 * cancelled or completed (this makes a certain amount of sense because
162 * successful cancellation - io_cancel() - does deliver the completion to
163 * userspace).
164 *
165 * And since most things don't implement kiocb cancellation and we'd really like
166 * kiocb completion to be lockless when possible, we use ki_cancel to
167 * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
168 * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
169 */
170 #define KIOCB_CANCELLED ((void *) (~0ULL))
171
172 struct aio_kiocb {
173 struct kiocb common;
174
175 struct kioctx *ki_ctx;
176 kiocb_cancel_fn *ki_cancel;
177
178 struct iocb __user *ki_user_iocb; /* user's aiocb */
179 __u64 ki_user_data; /* user's data for completion */
180
181 struct list_head ki_list; /* the aio core uses this
182 * for cancellation */
183
184 /*
185 * If the aio_resfd field of the userspace iocb is not zero,
186 * this is the underlying eventfd context to deliver events to.
187 */
188 struct eventfd_ctx *ki_eventfd;
189 };
190
191 /*------ sysctl variables----*/
192 static DEFINE_SPINLOCK(aio_nr_lock);
193 unsigned long aio_nr; /* current system wide number of aio requests */
194 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
195 /*----end sysctl variables---*/
196
197 static struct kmem_cache *kiocb_cachep;
198 static struct kmem_cache *kioctx_cachep;
199
200 static struct vfsmount *aio_mnt;
201
202 static const struct file_operations aio_ring_fops;
203 static const struct address_space_operations aio_ctx_aops;
204
205 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
206 {
207 struct qstr this = QSTR_INIT("[aio]", 5);
208 struct file *file;
209 struct path path;
210 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
211 if (IS_ERR(inode))
212 return ERR_CAST(inode);
213
214 inode->i_mapping->a_ops = &aio_ctx_aops;
215 inode->i_mapping->private_data = ctx;
216 inode->i_size = PAGE_SIZE * nr_pages;
217
218 path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
219 if (!path.dentry) {
220 iput(inode);
221 return ERR_PTR(-ENOMEM);
222 }
223 path.mnt = mntget(aio_mnt);
224
225 d_instantiate(path.dentry, inode);
226 file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
227 if (IS_ERR(file)) {
228 path_put(&path);
229 return file;
230 }
231
232 file->f_flags = O_RDWR;
233 return file;
234 }
235
236 static struct dentry *aio_mount(struct file_system_type *fs_type,
237 int flags, const char *dev_name, void *data)
238 {
239 static const struct dentry_operations ops = {
240 .d_dname = simple_dname,
241 };
242 return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
243 }
244
245 /* aio_setup
246 * Creates the slab caches used by the aio routines, panic on
247 * failure as this is done early during the boot sequence.
248 */
249 static int __init aio_setup(void)
250 {
251 static struct file_system_type aio_fs = {
252 .name = "aio",
253 .mount = aio_mount,
254 .kill_sb = kill_anon_super,
255 };
256 aio_mnt = kern_mount(&aio_fs);
257 if (IS_ERR(aio_mnt))
258 panic("Failed to create aio fs mount.");
259
260 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
261 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
262
263 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
264
265 return 0;
266 }
267 __initcall(aio_setup);
268
269 static void put_aio_ring_file(struct kioctx *ctx)
270 {
271 struct file *aio_ring_file = ctx->aio_ring_file;
272 if (aio_ring_file) {
273 truncate_setsize(aio_ring_file->f_inode, 0);
274
275 /* Prevent further access to the kioctx from migratepages */
276 spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
277 aio_ring_file->f_inode->i_mapping->private_data = NULL;
278 ctx->aio_ring_file = NULL;
279 spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
280
281 fput(aio_ring_file);
282 }
283 }
284
285 static void aio_free_ring(struct kioctx *ctx)
286 {
287 int i;
288
289 /* Disconnect the kiotx from the ring file. This prevents future
290 * accesses to the kioctx from page migration.
291 */
292 put_aio_ring_file(ctx);
293
294 for (i = 0; i < ctx->nr_pages; i++) {
295 struct page *page;
296 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
297 page_count(ctx->ring_pages[i]));
298 page = ctx->ring_pages[i];
299 if (!page)
300 continue;
301 ctx->ring_pages[i] = NULL;
302 put_page(page);
303 }
304
305 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
306 kfree(ctx->ring_pages);
307 ctx->ring_pages = NULL;
308 }
309 }
310
311 static int aio_ring_mremap(struct vm_area_struct *vma)
312 {
313 struct file *file = vma->vm_file;
314 struct mm_struct *mm = vma->vm_mm;
315 struct kioctx_table *table;
316 int i, res = -EINVAL;
317
318 spin_lock(&mm->ioctx_lock);
319 rcu_read_lock();
320 table = rcu_dereference(mm->ioctx_table);
321 for (i = 0; i < table->nr; i++) {
322 struct kioctx *ctx;
323
324 ctx = table->table[i];
325 if (ctx && ctx->aio_ring_file == file) {
326 if (!atomic_read(&ctx->dead)) {
327 ctx->user_id = ctx->mmap_base = vma->vm_start;
328 res = 0;
329 }
330 break;
331 }
332 }
333
334 rcu_read_unlock();
335 spin_unlock(&mm->ioctx_lock);
336 return res;
337 }
338
339 static const struct vm_operations_struct aio_ring_vm_ops = {
340 .mremap = aio_ring_mremap,
341 #if IS_ENABLED(CONFIG_MMU)
342 .fault = filemap_fault,
343 .map_pages = filemap_map_pages,
344 .page_mkwrite = filemap_page_mkwrite,
345 #endif
346 };
347
348 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
349 {
350 vma->vm_flags |= VM_DONTEXPAND;
351 vma->vm_ops = &aio_ring_vm_ops;
352 return 0;
353 }
354
355 static const struct file_operations aio_ring_fops = {
356 .mmap = aio_ring_mmap,
357 };
358
359 #if IS_ENABLED(CONFIG_MIGRATION)
360 static int aio_migratepage(struct address_space *mapping, struct page *new,
361 struct page *old, enum migrate_mode mode)
362 {
363 struct kioctx *ctx;
364 unsigned long flags;
365 pgoff_t idx;
366 int rc;
367
368 rc = 0;
369
370 /* mapping->private_lock here protects against the kioctx teardown. */
371 spin_lock(&mapping->private_lock);
372 ctx = mapping->private_data;
373 if (!ctx) {
374 rc = -EINVAL;
375 goto out;
376 }
377
378 /* The ring_lock mutex. The prevents aio_read_events() from writing
379 * to the ring's head, and prevents page migration from mucking in
380 * a partially initialized kiotx.
381 */
382 if (!mutex_trylock(&ctx->ring_lock)) {
383 rc = -EAGAIN;
384 goto out;
385 }
386
387 idx = old->index;
388 if (idx < (pgoff_t)ctx->nr_pages) {
389 /* Make sure the old page hasn't already been changed */
390 if (ctx->ring_pages[idx] != old)
391 rc = -EAGAIN;
392 } else
393 rc = -EINVAL;
394
395 if (rc != 0)
396 goto out_unlock;
397
398 /* Writeback must be complete */
399 BUG_ON(PageWriteback(old));
400 get_page(new);
401
402 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
403 if (rc != MIGRATEPAGE_SUCCESS) {
404 put_page(new);
405 goto out_unlock;
406 }
407
408 /* Take completion_lock to prevent other writes to the ring buffer
409 * while the old page is copied to the new. This prevents new
410 * events from being lost.
411 */
412 spin_lock_irqsave(&ctx->completion_lock, flags);
413 migrate_page_copy(new, old);
414 BUG_ON(ctx->ring_pages[idx] != old);
415 ctx->ring_pages[idx] = new;
416 spin_unlock_irqrestore(&ctx->completion_lock, flags);
417
418 /* The old page is no longer accessible. */
419 put_page(old);
420
421 out_unlock:
422 mutex_unlock(&ctx->ring_lock);
423 out:
424 spin_unlock(&mapping->private_lock);
425 return rc;
426 }
427 #endif
428
429 static const struct address_space_operations aio_ctx_aops = {
430 .set_page_dirty = __set_page_dirty_no_writeback,
431 #if IS_ENABLED(CONFIG_MIGRATION)
432 .migratepage = aio_migratepage,
433 #endif
434 };
435
436 static int aio_setup_ring(struct kioctx *ctx)
437 {
438 struct aio_ring *ring;
439 unsigned nr_events = ctx->max_reqs;
440 struct mm_struct *mm = current->mm;
441 unsigned long size, unused;
442 int nr_pages;
443 int i;
444 struct file *file;
445
446 /* Compensate for the ring buffer's head/tail overlap entry */
447 nr_events += 2; /* 1 is required, 2 for good luck */
448
449 size = sizeof(struct aio_ring);
450 size += sizeof(struct io_event) * nr_events;
451
452 nr_pages = PFN_UP(size);
453 if (nr_pages < 0)
454 return -EINVAL;
455
456 file = aio_private_file(ctx, nr_pages);
457 if (IS_ERR(file)) {
458 ctx->aio_ring_file = NULL;
459 return -ENOMEM;
460 }
461
462 ctx->aio_ring_file = file;
463 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
464 / sizeof(struct io_event);
465
466 ctx->ring_pages = ctx->internal_pages;
467 if (nr_pages > AIO_RING_PAGES) {
468 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
469 GFP_KERNEL);
470 if (!ctx->ring_pages) {
471 put_aio_ring_file(ctx);
472 return -ENOMEM;
473 }
474 }
475
476 for (i = 0; i < nr_pages; i++) {
477 struct page *page;
478 page = find_or_create_page(file->f_inode->i_mapping,
479 i, GFP_HIGHUSER | __GFP_ZERO);
480 if (!page)
481 break;
482 pr_debug("pid(%d) page[%d]->count=%d\n",
483 current->pid, i, page_count(page));
484 SetPageUptodate(page);
485 unlock_page(page);
486
487 ctx->ring_pages[i] = page;
488 }
489 ctx->nr_pages = i;
490
491 if (unlikely(i != nr_pages)) {
492 aio_free_ring(ctx);
493 return -ENOMEM;
494 }
495
496 ctx->mmap_size = nr_pages * PAGE_SIZE;
497 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
498
499 down_write(&mm->mmap_sem);
500 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
501 PROT_READ | PROT_WRITE,
502 MAP_SHARED, 0, &unused);
503 up_write(&mm->mmap_sem);
504 if (IS_ERR((void *)ctx->mmap_base)) {
505 ctx->mmap_size = 0;
506 aio_free_ring(ctx);
507 return -ENOMEM;
508 }
509
510 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
511
512 ctx->user_id = ctx->mmap_base;
513 ctx->nr_events = nr_events; /* trusted copy */
514
515 ring = kmap_atomic(ctx->ring_pages[0]);
516 ring->nr = nr_events; /* user copy */
517 ring->id = ~0U;
518 ring->head = ring->tail = 0;
519 ring->magic = AIO_RING_MAGIC;
520 ring->compat_features = AIO_RING_COMPAT_FEATURES;
521 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
522 ring->header_length = sizeof(struct aio_ring);
523 kunmap_atomic(ring);
524 flush_dcache_page(ctx->ring_pages[0]);
525
526 return 0;
527 }
528
529 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
530 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
531 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
532
533 void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
534 {
535 struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
536 struct kioctx *ctx = req->ki_ctx;
537 unsigned long flags;
538
539 spin_lock_irqsave(&ctx->ctx_lock, flags);
540
541 if (!req->ki_list.next)
542 list_add(&req->ki_list, &ctx->active_reqs);
543
544 req->ki_cancel = cancel;
545
546 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
547 }
548 EXPORT_SYMBOL(kiocb_set_cancel_fn);
549
550 static int kiocb_cancel(struct aio_kiocb *kiocb)
551 {
552 kiocb_cancel_fn *old, *cancel;
553
554 /*
555 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
556 * actually has a cancel function, hence the cmpxchg()
557 */
558
559 cancel = ACCESS_ONCE(kiocb->ki_cancel);
560 do {
561 if (!cancel || cancel == KIOCB_CANCELLED)
562 return -EINVAL;
563
564 old = cancel;
565 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
566 } while (cancel != old);
567
568 return cancel(&kiocb->common);
569 }
570
571 static void free_ioctx(struct work_struct *work)
572 {
573 struct kioctx *ctx = container_of(work, struct kioctx, free_work);
574
575 pr_debug("freeing %p\n", ctx);
576
577 aio_free_ring(ctx);
578 free_percpu(ctx->cpu);
579 percpu_ref_exit(&ctx->reqs);
580 percpu_ref_exit(&ctx->users);
581 kmem_cache_free(kioctx_cachep, ctx);
582 }
583
584 static void free_ioctx_reqs(struct percpu_ref *ref)
585 {
586 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
587
588 /* At this point we know that there are no any in-flight requests */
589 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
590 complete(&ctx->rq_wait->comp);
591
592 INIT_WORK(&ctx->free_work, free_ioctx);
593 schedule_work(&ctx->free_work);
594 }
595
596 /*
597 * When this function runs, the kioctx has been removed from the "hash table"
598 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
599 * now it's safe to cancel any that need to be.
600 */
601 static void free_ioctx_users(struct percpu_ref *ref)
602 {
603 struct kioctx *ctx = container_of(ref, struct kioctx, users);
604 struct aio_kiocb *req;
605
606 spin_lock_irq(&ctx->ctx_lock);
607
608 while (!list_empty(&ctx->active_reqs)) {
609 req = list_first_entry(&ctx->active_reqs,
610 struct aio_kiocb, ki_list);
611
612 list_del_init(&req->ki_list);
613 kiocb_cancel(req);
614 }
615
616 spin_unlock_irq(&ctx->ctx_lock);
617
618 percpu_ref_kill(&ctx->reqs);
619 percpu_ref_put(&ctx->reqs);
620 }
621
622 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
623 {
624 unsigned i, new_nr;
625 struct kioctx_table *table, *old;
626 struct aio_ring *ring;
627
628 spin_lock(&mm->ioctx_lock);
629 table = rcu_dereference_raw(mm->ioctx_table);
630
631 while (1) {
632 if (table)
633 for (i = 0; i < table->nr; i++)
634 if (!table->table[i]) {
635 ctx->id = i;
636 table->table[i] = ctx;
637 spin_unlock(&mm->ioctx_lock);
638
639 /* While kioctx setup is in progress,
640 * we are protected from page migration
641 * changes ring_pages by ->ring_lock.
642 */
643 ring = kmap_atomic(ctx->ring_pages[0]);
644 ring->id = ctx->id;
645 kunmap_atomic(ring);
646 return 0;
647 }
648
649 new_nr = (table ? table->nr : 1) * 4;
650 spin_unlock(&mm->ioctx_lock);
651
652 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
653 new_nr, GFP_KERNEL);
654 if (!table)
655 return -ENOMEM;
656
657 table->nr = new_nr;
658
659 spin_lock(&mm->ioctx_lock);
660 old = rcu_dereference_raw(mm->ioctx_table);
661
662 if (!old) {
663 rcu_assign_pointer(mm->ioctx_table, table);
664 } else if (table->nr > old->nr) {
665 memcpy(table->table, old->table,
666 old->nr * sizeof(struct kioctx *));
667
668 rcu_assign_pointer(mm->ioctx_table, table);
669 kfree_rcu(old, rcu);
670 } else {
671 kfree(table);
672 table = old;
673 }
674 }
675 }
676
677 static void aio_nr_sub(unsigned nr)
678 {
679 spin_lock(&aio_nr_lock);
680 if (WARN_ON(aio_nr - nr > aio_nr))
681 aio_nr = 0;
682 else
683 aio_nr -= nr;
684 spin_unlock(&aio_nr_lock);
685 }
686
687 /* ioctx_alloc
688 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
689 */
690 static struct kioctx *ioctx_alloc(unsigned nr_events)
691 {
692 struct mm_struct *mm = current->mm;
693 struct kioctx *ctx;
694 int err = -ENOMEM;
695
696 /*
697 * We keep track of the number of available ringbuffer slots, to prevent
698 * overflow (reqs_available), and we also use percpu counters for this.
699 *
700 * So since up to half the slots might be on other cpu's percpu counters
701 * and unavailable, double nr_events so userspace sees what they
702 * expected: additionally, we move req_batch slots to/from percpu
703 * counters at a time, so make sure that isn't 0:
704 */
705 nr_events = max(nr_events, num_possible_cpus() * 4);
706 nr_events *= 2;
707
708 /* Prevent overflows */
709 if (nr_events > (0x10000000U / sizeof(struct io_event))) {
710 pr_debug("ENOMEM: nr_events too high\n");
711 return ERR_PTR(-EINVAL);
712 }
713
714 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
715 return ERR_PTR(-EAGAIN);
716
717 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
718 if (!ctx)
719 return ERR_PTR(-ENOMEM);
720
721 ctx->max_reqs = nr_events;
722
723 spin_lock_init(&ctx->ctx_lock);
724 spin_lock_init(&ctx->completion_lock);
725 mutex_init(&ctx->ring_lock);
726 /* Protect against page migration throughout kiotx setup by keeping
727 * the ring_lock mutex held until setup is complete. */
728 mutex_lock(&ctx->ring_lock);
729 init_waitqueue_head(&ctx->wait);
730
731 INIT_LIST_HEAD(&ctx->active_reqs);
732
733 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
734 goto err;
735
736 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
737 goto err;
738
739 ctx->cpu = alloc_percpu(struct kioctx_cpu);
740 if (!ctx->cpu)
741 goto err;
742
743 err = aio_setup_ring(ctx);
744 if (err < 0)
745 goto err;
746
747 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
748 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
749 if (ctx->req_batch < 1)
750 ctx->req_batch = 1;
751
752 /* limit the number of system wide aios */
753 spin_lock(&aio_nr_lock);
754 if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
755 aio_nr + nr_events < aio_nr) {
756 spin_unlock(&aio_nr_lock);
757 err = -EAGAIN;
758 goto err_ctx;
759 }
760 aio_nr += ctx->max_reqs;
761 spin_unlock(&aio_nr_lock);
762
763 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
764 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
765
766 err = ioctx_add_table(ctx, mm);
767 if (err)
768 goto err_cleanup;
769
770 /* Release the ring_lock mutex now that all setup is complete. */
771 mutex_unlock(&ctx->ring_lock);
772
773 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
774 ctx, ctx->user_id, mm, ctx->nr_events);
775 return ctx;
776
777 err_cleanup:
778 aio_nr_sub(ctx->max_reqs);
779 err_ctx:
780 atomic_set(&ctx->dead, 1);
781 if (ctx->mmap_size)
782 vm_munmap(ctx->mmap_base, ctx->mmap_size);
783 aio_free_ring(ctx);
784 err:
785 mutex_unlock(&ctx->ring_lock);
786 free_percpu(ctx->cpu);
787 percpu_ref_exit(&ctx->reqs);
788 percpu_ref_exit(&ctx->users);
789 kmem_cache_free(kioctx_cachep, ctx);
790 pr_debug("error allocating ioctx %d\n", err);
791 return ERR_PTR(err);
792 }
793
794 /* kill_ioctx
795 * Cancels all outstanding aio requests on an aio context. Used
796 * when the processes owning a context have all exited to encourage
797 * the rapid destruction of the kioctx.
798 */
799 static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
800 struct ctx_rq_wait *wait)
801 {
802 struct kioctx_table *table;
803
804 spin_lock(&mm->ioctx_lock);
805 if (atomic_xchg(&ctx->dead, 1)) {
806 spin_unlock(&mm->ioctx_lock);
807 return -EINVAL;
808 }
809
810 table = rcu_dereference_raw(mm->ioctx_table);
811 WARN_ON(ctx != table->table[ctx->id]);
812 table->table[ctx->id] = NULL;
813 spin_unlock(&mm->ioctx_lock);
814
815 /* percpu_ref_kill() will do the necessary call_rcu() */
816 wake_up_all(&ctx->wait);
817
818 /*
819 * It'd be more correct to do this in free_ioctx(), after all
820 * the outstanding kiocbs have finished - but by then io_destroy
821 * has already returned, so io_setup() could potentially return
822 * -EAGAIN with no ioctxs actually in use (as far as userspace
823 * could tell).
824 */
825 aio_nr_sub(ctx->max_reqs);
826
827 if (ctx->mmap_size)
828 vm_munmap(ctx->mmap_base, ctx->mmap_size);
829
830 ctx->rq_wait = wait;
831 percpu_ref_kill(&ctx->users);
832 return 0;
833 }
834
835 /*
836 * exit_aio: called when the last user of mm goes away. At this point, there is
837 * no way for any new requests to be submited or any of the io_* syscalls to be
838 * called on the context.
839 *
840 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
841 * them.
842 */
843 void exit_aio(struct mm_struct *mm)
844 {
845 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
846 struct ctx_rq_wait wait;
847 int i, skipped;
848
849 if (!table)
850 return;
851
852 atomic_set(&wait.count, table->nr);
853 init_completion(&wait.comp);
854
855 skipped = 0;
856 for (i = 0; i < table->nr; ++i) {
857 struct kioctx *ctx = table->table[i];
858
859 if (!ctx) {
860 skipped++;
861 continue;
862 }
863
864 /*
865 * We don't need to bother with munmap() here - exit_mmap(mm)
866 * is coming and it'll unmap everything. And we simply can't,
867 * this is not necessarily our ->mm.
868 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
869 * that it needs to unmap the area, just set it to 0.
870 */
871 ctx->mmap_size = 0;
872 kill_ioctx(mm, ctx, &wait);
873 }
874
875 if (!atomic_sub_and_test(skipped, &wait.count)) {
876 /* Wait until all IO for the context are done. */
877 wait_for_completion(&wait.comp);
878 }
879
880 RCU_INIT_POINTER(mm->ioctx_table, NULL);
881 kfree(table);
882 }
883
884 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
885 {
886 struct kioctx_cpu *kcpu;
887 unsigned long flags;
888
889 local_irq_save(flags);
890 kcpu = this_cpu_ptr(ctx->cpu);
891 kcpu->reqs_available += nr;
892
893 while (kcpu->reqs_available >= ctx->req_batch * 2) {
894 kcpu->reqs_available -= ctx->req_batch;
895 atomic_add(ctx->req_batch, &ctx->reqs_available);
896 }
897
898 local_irq_restore(flags);
899 }
900
901 static bool get_reqs_available(struct kioctx *ctx)
902 {
903 struct kioctx_cpu *kcpu;
904 bool ret = false;
905 unsigned long flags;
906
907 local_irq_save(flags);
908 kcpu = this_cpu_ptr(ctx->cpu);
909 if (!kcpu->reqs_available) {
910 int old, avail = atomic_read(&ctx->reqs_available);
911
912 do {
913 if (avail < ctx->req_batch)
914 goto out;
915
916 old = avail;
917 avail = atomic_cmpxchg(&ctx->reqs_available,
918 avail, avail - ctx->req_batch);
919 } while (avail != old);
920
921 kcpu->reqs_available += ctx->req_batch;
922 }
923
924 ret = true;
925 kcpu->reqs_available--;
926 out:
927 local_irq_restore(flags);
928 return ret;
929 }
930
931 /* refill_reqs_available
932 * Updates the reqs_available reference counts used for tracking the
933 * number of free slots in the completion ring. This can be called
934 * from aio_complete() (to optimistically update reqs_available) or
935 * from aio_get_req() (the we're out of events case). It must be
936 * called holding ctx->completion_lock.
937 */
938 static void refill_reqs_available(struct kioctx *ctx, unsigned head,
939 unsigned tail)
940 {
941 unsigned events_in_ring, completed;
942
943 /* Clamp head since userland can write to it. */
944 head %= ctx->nr_events;
945 if (head <= tail)
946 events_in_ring = tail - head;
947 else
948 events_in_ring = ctx->nr_events - (head - tail);
949
950 completed = ctx->completed_events;
951 if (events_in_ring < completed)
952 completed -= events_in_ring;
953 else
954 completed = 0;
955
956 if (!completed)
957 return;
958
959 ctx->completed_events -= completed;
960 put_reqs_available(ctx, completed);
961 }
962
963 /* user_refill_reqs_available
964 * Called to refill reqs_available when aio_get_req() encounters an
965 * out of space in the completion ring.
966 */
967 static void user_refill_reqs_available(struct kioctx *ctx)
968 {
969 spin_lock_irq(&ctx->completion_lock);
970 if (ctx->completed_events) {
971 struct aio_ring *ring;
972 unsigned head;
973
974 /* Access of ring->head may race with aio_read_events_ring()
975 * here, but that's okay since whether we read the old version
976 * or the new version, and either will be valid. The important
977 * part is that head cannot pass tail since we prevent
978 * aio_complete() from updating tail by holding
979 * ctx->completion_lock. Even if head is invalid, the check
980 * against ctx->completed_events below will make sure we do the
981 * safe/right thing.
982 */
983 ring = kmap_atomic(ctx->ring_pages[0]);
984 head = ring->head;
985 kunmap_atomic(ring);
986
987 refill_reqs_available(ctx, head, ctx->tail);
988 }
989
990 spin_unlock_irq(&ctx->completion_lock);
991 }
992
993 /* aio_get_req
994 * Allocate a slot for an aio request.
995 * Returns NULL if no requests are free.
996 */
997 static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
998 {
999 struct aio_kiocb *req;
1000
1001 if (!get_reqs_available(ctx)) {
1002 user_refill_reqs_available(ctx);
1003 if (!get_reqs_available(ctx))
1004 return NULL;
1005 }
1006
1007 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
1008 if (unlikely(!req))
1009 goto out_put;
1010
1011 percpu_ref_get(&ctx->reqs);
1012
1013 req->ki_ctx = ctx;
1014 return req;
1015 out_put:
1016 put_reqs_available(ctx, 1);
1017 return NULL;
1018 }
1019
1020 static void kiocb_free(struct aio_kiocb *req)
1021 {
1022 if (req->common.ki_filp)
1023 fput(req->common.ki_filp);
1024 if (req->ki_eventfd != NULL)
1025 eventfd_ctx_put(req->ki_eventfd);
1026 kmem_cache_free(kiocb_cachep, req);
1027 }
1028
1029 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1030 {
1031 struct aio_ring __user *ring = (void __user *)ctx_id;
1032 struct mm_struct *mm = current->mm;
1033 struct kioctx *ctx, *ret = NULL;
1034 struct kioctx_table *table;
1035 unsigned id;
1036
1037 if (get_user(id, &ring->id))
1038 return NULL;
1039
1040 rcu_read_lock();
1041 table = rcu_dereference(mm->ioctx_table);
1042
1043 if (!table || id >= table->nr)
1044 goto out;
1045
1046 ctx = table->table[id];
1047 if (ctx && ctx->user_id == ctx_id) {
1048 percpu_ref_get(&ctx->users);
1049 ret = ctx;
1050 }
1051 out:
1052 rcu_read_unlock();
1053 return ret;
1054 }
1055
1056 /* aio_complete
1057 * Called when the io request on the given iocb is complete.
1058 */
1059 static void aio_complete(struct kiocb *kiocb, long res, long res2)
1060 {
1061 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
1062 struct kioctx *ctx = iocb->ki_ctx;
1063 struct aio_ring *ring;
1064 struct io_event *ev_page, *event;
1065 unsigned tail, pos, head;
1066 unsigned long flags;
1067
1068 /*
1069 * Special case handling for sync iocbs:
1070 * - events go directly into the iocb for fast handling
1071 * - the sync task with the iocb in its stack holds the single iocb
1072 * ref, no other paths have a way to get another ref
1073 * - the sync task helpfully left a reference to itself in the iocb
1074 */
1075 BUG_ON(is_sync_kiocb(kiocb));
1076
1077 if (iocb->ki_list.next) {
1078 unsigned long flags;
1079
1080 spin_lock_irqsave(&ctx->ctx_lock, flags);
1081 list_del(&iocb->ki_list);
1082 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1083 }
1084
1085 /*
1086 * Add a completion event to the ring buffer. Must be done holding
1087 * ctx->completion_lock to prevent other code from messing with the tail
1088 * pointer since we might be called from irq context.
1089 */
1090 spin_lock_irqsave(&ctx->completion_lock, flags);
1091
1092 tail = ctx->tail;
1093 pos = tail + AIO_EVENTS_OFFSET;
1094
1095 if (++tail >= ctx->nr_events)
1096 tail = 0;
1097
1098 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1099 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1100
1101 event->obj = (u64)(unsigned long)iocb->ki_user_iocb;
1102 event->data = iocb->ki_user_data;
1103 event->res = res;
1104 event->res2 = res2;
1105
1106 kunmap_atomic(ev_page);
1107 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1108
1109 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
1110 ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data,
1111 res, res2);
1112
1113 /* after flagging the request as done, we
1114 * must never even look at it again
1115 */
1116 smp_wmb(); /* make event visible before updating tail */
1117
1118 ctx->tail = tail;
1119
1120 ring = kmap_atomic(ctx->ring_pages[0]);
1121 head = ring->head;
1122 ring->tail = tail;
1123 kunmap_atomic(ring);
1124 flush_dcache_page(ctx->ring_pages[0]);
1125
1126 ctx->completed_events++;
1127 if (ctx->completed_events > 1)
1128 refill_reqs_available(ctx, head, tail);
1129 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1130
1131 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1132
1133 /*
1134 * Check if the user asked us to deliver the result through an
1135 * eventfd. The eventfd_signal() function is safe to be called
1136 * from IRQ context.
1137 */
1138 if (iocb->ki_eventfd != NULL)
1139 eventfd_signal(iocb->ki_eventfd, 1);
1140
1141 /* everything turned out well, dispose of the aiocb. */
1142 kiocb_free(iocb);
1143
1144 /*
1145 * We have to order our ring_info tail store above and test
1146 * of the wait list below outside the wait lock. This is
1147 * like in wake_up_bit() where clearing a bit has to be
1148 * ordered with the unlocked test.
1149 */
1150 smp_mb();
1151
1152 if (waitqueue_active(&ctx->wait))
1153 wake_up(&ctx->wait);
1154
1155 percpu_ref_put(&ctx->reqs);
1156 }
1157
1158 /* aio_read_events_ring
1159 * Pull an event off of the ioctx's event ring. Returns the number of
1160 * events fetched
1161 */
1162 static long aio_read_events_ring(struct kioctx *ctx,
1163 struct io_event __user *event, long nr)
1164 {
1165 struct aio_ring *ring;
1166 unsigned head, tail, pos;
1167 long ret = 0;
1168 int copy_ret;
1169
1170 /*
1171 * The mutex can block and wake us up and that will cause
1172 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1173 * and repeat. This should be rare enough that it doesn't cause
1174 * peformance issues. See the comment in read_events() for more detail.
1175 */
1176 sched_annotate_sleep();
1177 mutex_lock(&ctx->ring_lock);
1178
1179 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1180 ring = kmap_atomic(ctx->ring_pages[0]);
1181 head = ring->head;
1182 tail = ring->tail;
1183 kunmap_atomic(ring);
1184
1185 /*
1186 * Ensure that once we've read the current tail pointer, that
1187 * we also see the events that were stored up to the tail.
1188 */
1189 smp_rmb();
1190
1191 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1192
1193 if (head == tail)
1194 goto out;
1195
1196 head %= ctx->nr_events;
1197 tail %= ctx->nr_events;
1198
1199 while (ret < nr) {
1200 long avail;
1201 struct io_event *ev;
1202 struct page *page;
1203
1204 avail = (head <= tail ? tail : ctx->nr_events) - head;
1205 if (head == tail)
1206 break;
1207
1208 avail = min(avail, nr - ret);
1209 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
1210 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
1211
1212 pos = head + AIO_EVENTS_OFFSET;
1213 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1214 pos %= AIO_EVENTS_PER_PAGE;
1215
1216 ev = kmap(page);
1217 copy_ret = copy_to_user(event + ret, ev + pos,
1218 sizeof(*ev) * avail);
1219 kunmap(page);
1220
1221 if (unlikely(copy_ret)) {
1222 ret = -EFAULT;
1223 goto out;
1224 }
1225
1226 ret += avail;
1227 head += avail;
1228 head %= ctx->nr_events;
1229 }
1230
1231 ring = kmap_atomic(ctx->ring_pages[0]);
1232 ring->head = head;
1233 kunmap_atomic(ring);
1234 flush_dcache_page(ctx->ring_pages[0]);
1235
1236 pr_debug("%li h%u t%u\n", ret, head, tail);
1237 out:
1238 mutex_unlock(&ctx->ring_lock);
1239
1240 return ret;
1241 }
1242
1243 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1244 struct io_event __user *event, long *i)
1245 {
1246 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1247
1248 if (ret > 0)
1249 *i += ret;
1250
1251 if (unlikely(atomic_read(&ctx->dead)))
1252 ret = -EINVAL;
1253
1254 if (!*i)
1255 *i = ret;
1256
1257 return ret < 0 || *i >= min_nr;
1258 }
1259
1260 static long read_events(struct kioctx *ctx, long min_nr, long nr,
1261 struct io_event __user *event,
1262 struct timespec __user *timeout)
1263 {
1264 ktime_t until = { .tv64 = KTIME_MAX };
1265 long ret = 0;
1266
1267 if (timeout) {
1268 struct timespec ts;
1269
1270 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1271 return -EFAULT;
1272
1273 until = timespec_to_ktime(ts);
1274 }
1275
1276 /*
1277 * Note that aio_read_events() is being called as the conditional - i.e.
1278 * we're calling it after prepare_to_wait() has set task state to
1279 * TASK_INTERRUPTIBLE.
1280 *
1281 * But aio_read_events() can block, and if it blocks it's going to flip
1282 * the task state back to TASK_RUNNING.
1283 *
1284 * This should be ok, provided it doesn't flip the state back to
1285 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1286 * will only happen if the mutex_lock() call blocks, and we then find
1287 * the ringbuffer empty. So in practice we should be ok, but it's
1288 * something to be aware of when touching this code.
1289 */
1290 if (until.tv64 == 0)
1291 aio_read_events(ctx, min_nr, nr, event, &ret);
1292 else
1293 wait_event_interruptible_hrtimeout(ctx->wait,
1294 aio_read_events(ctx, min_nr, nr, event, &ret),
1295 until);
1296
1297 if (!ret && signal_pending(current))
1298 ret = -EINTR;
1299
1300 return ret;
1301 }
1302
1303 /* sys_io_setup:
1304 * Create an aio_context capable of receiving at least nr_events.
1305 * ctxp must not point to an aio_context that already exists, and
1306 * must be initialized to 0 prior to the call. On successful
1307 * creation of the aio_context, *ctxp is filled in with the resulting
1308 * handle. May fail with -EINVAL if *ctxp is not initialized,
1309 * if the specified nr_events exceeds internal limits. May fail
1310 * with -EAGAIN if the specified nr_events exceeds the user's limit
1311 * of available events. May fail with -ENOMEM if insufficient kernel
1312 * resources are available. May fail with -EFAULT if an invalid
1313 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1314 * implemented.
1315 */
1316 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1317 {
1318 struct kioctx *ioctx = NULL;
1319 unsigned long ctx;
1320 long ret;
1321
1322 ret = get_user(ctx, ctxp);
1323 if (unlikely(ret))
1324 goto out;
1325
1326 ret = -EINVAL;
1327 if (unlikely(ctx || nr_events == 0)) {
1328 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1329 ctx, nr_events);
1330 goto out;
1331 }
1332
1333 ioctx = ioctx_alloc(nr_events);
1334 ret = PTR_ERR(ioctx);
1335 if (!IS_ERR(ioctx)) {
1336 ret = put_user(ioctx->user_id, ctxp);
1337 if (ret)
1338 kill_ioctx(current->mm, ioctx, NULL);
1339 percpu_ref_put(&ioctx->users);
1340 }
1341
1342 out:
1343 return ret;
1344 }
1345
1346 /* sys_io_destroy:
1347 * Destroy the aio_context specified. May cancel any outstanding
1348 * AIOs and block on completion. Will fail with -ENOSYS if not
1349 * implemented. May fail with -EINVAL if the context pointed to
1350 * is invalid.
1351 */
1352 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1353 {
1354 struct kioctx *ioctx = lookup_ioctx(ctx);
1355 if (likely(NULL != ioctx)) {
1356 struct ctx_rq_wait wait;
1357 int ret;
1358
1359 init_completion(&wait.comp);
1360 atomic_set(&wait.count, 1);
1361
1362 /* Pass requests_done to kill_ioctx() where it can be set
1363 * in a thread-safe way. If we try to set it here then we have
1364 * a race condition if two io_destroy() called simultaneously.
1365 */
1366 ret = kill_ioctx(current->mm, ioctx, &wait);
1367 percpu_ref_put(&ioctx->users);
1368
1369 /* Wait until all IO for the context are done. Otherwise kernel
1370 * keep using user-space buffers even if user thinks the context
1371 * is destroyed.
1372 */
1373 if (!ret)
1374 wait_for_completion(&wait.comp);
1375
1376 return ret;
1377 }
1378 pr_debug("EINVAL: invalid context id\n");
1379 return -EINVAL;
1380 }
1381
1382 typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
1383
1384 static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len,
1385 struct iovec **iovec,
1386 bool compat,
1387 struct iov_iter *iter)
1388 {
1389 #ifdef CONFIG_COMPAT
1390 if (compat)
1391 return compat_import_iovec(rw,
1392 (struct compat_iovec __user *)buf,
1393 len, UIO_FASTIOV, iovec, iter);
1394 #endif
1395 return import_iovec(rw, (struct iovec __user *)buf,
1396 len, UIO_FASTIOV, iovec, iter);
1397 }
1398
1399 /*
1400 * aio_run_iocb:
1401 * Performs the initial checks and io submission.
1402 */
1403 static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
1404 char __user *buf, size_t len, bool compat)
1405 {
1406 struct file *file = req->ki_filp;
1407 ssize_t ret;
1408 int rw;
1409 fmode_t mode;
1410 rw_iter_op *iter_op;
1411 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1412 struct iov_iter iter;
1413
1414 switch (opcode) {
1415 case IOCB_CMD_PREAD:
1416 case IOCB_CMD_PREADV:
1417 mode = FMODE_READ;
1418 rw = READ;
1419 iter_op = file->f_op->read_iter;
1420 goto rw_common;
1421
1422 case IOCB_CMD_PWRITE:
1423 case IOCB_CMD_PWRITEV:
1424 mode = FMODE_WRITE;
1425 rw = WRITE;
1426 iter_op = file->f_op->write_iter;
1427 goto rw_common;
1428 rw_common:
1429 if (unlikely(!(file->f_mode & mode)))
1430 return -EBADF;
1431
1432 if (!iter_op)
1433 return -EINVAL;
1434
1435 if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV)
1436 ret = aio_setup_vectored_rw(rw, buf, len,
1437 &iovec, compat, &iter);
1438 else {
1439 ret = import_single_range(rw, buf, len, iovec, &iter);
1440 iovec = NULL;
1441 }
1442 if (!ret)
1443 ret = rw_verify_area(rw, file, &req->ki_pos,
1444 iov_iter_count(&iter));
1445 if (ret < 0) {
1446 kfree(iovec);
1447 return ret;
1448 }
1449
1450 len = ret;
1451
1452 if (rw == WRITE)
1453 file_start_write(file);
1454
1455 ret = iter_op(req, &iter);
1456
1457 if (rw == WRITE)
1458 file_end_write(file);
1459 kfree(iovec);
1460 break;
1461
1462 case IOCB_CMD_FDSYNC:
1463 if (!file->f_op->aio_fsync)
1464 return -EINVAL;
1465
1466 ret = file->f_op->aio_fsync(req, 1);
1467 break;
1468
1469 case IOCB_CMD_FSYNC:
1470 if (!file->f_op->aio_fsync)
1471 return -EINVAL;
1472
1473 ret = file->f_op->aio_fsync(req, 0);
1474 break;
1475
1476 default:
1477 pr_debug("EINVAL: no operation provided\n");
1478 return -EINVAL;
1479 }
1480
1481 if (ret != -EIOCBQUEUED) {
1482 /*
1483 * There's no easy way to restart the syscall since other AIO's
1484 * may be already running. Just fail this IO with EINTR.
1485 */
1486 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1487 ret == -ERESTARTNOHAND ||
1488 ret == -ERESTART_RESTARTBLOCK))
1489 ret = -EINTR;
1490 aio_complete(req, ret, 0);
1491 }
1492
1493 return 0;
1494 }
1495
1496 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1497 struct iocb *iocb, bool compat)
1498 {
1499 struct aio_kiocb *req;
1500 ssize_t ret;
1501
1502 /* enforce forwards compatibility on users */
1503 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1504 pr_debug("EINVAL: reserve field set\n");
1505 return -EINVAL;
1506 }
1507
1508 /* prevent overflows */
1509 if (unlikely(
1510 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1511 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1512 ((ssize_t)iocb->aio_nbytes < 0)
1513 )) {
1514 pr_debug("EINVAL: overflow check\n");
1515 return -EINVAL;
1516 }
1517
1518 req = aio_get_req(ctx);
1519 if (unlikely(!req))
1520 return -EAGAIN;
1521
1522 req->common.ki_filp = fget(iocb->aio_fildes);
1523 if (unlikely(!req->common.ki_filp)) {
1524 ret = -EBADF;
1525 goto out_put_req;
1526 }
1527 req->common.ki_pos = iocb->aio_offset;
1528 req->common.ki_complete = aio_complete;
1529 req->common.ki_flags = iocb_flags(req->common.ki_filp);
1530
1531 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1532 /*
1533 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1534 * instance of the file* now. The file descriptor must be
1535 * an eventfd() fd, and will be signaled for each completed
1536 * event using the eventfd_signal() function.
1537 */
1538 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1539 if (IS_ERR(req->ki_eventfd)) {
1540 ret = PTR_ERR(req->ki_eventfd);
1541 req->ki_eventfd = NULL;
1542 goto out_put_req;
1543 }
1544
1545 req->common.ki_flags |= IOCB_EVENTFD;
1546 }
1547
1548 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1549 if (unlikely(ret)) {
1550 pr_debug("EFAULT: aio_key\n");
1551 goto out_put_req;
1552 }
1553
1554 req->ki_user_iocb = user_iocb;
1555 req->ki_user_data = iocb->aio_data;
1556
1557 ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode,
1558 (char __user *)(unsigned long)iocb->aio_buf,
1559 iocb->aio_nbytes,
1560 compat);
1561 if (ret)
1562 goto out_put_req;
1563
1564 return 0;
1565 out_put_req:
1566 put_reqs_available(ctx, 1);
1567 percpu_ref_put(&ctx->reqs);
1568 kiocb_free(req);
1569 return ret;
1570 }
1571
1572 long do_io_submit(aio_context_t ctx_id, long nr,
1573 struct iocb __user *__user *iocbpp, bool compat)
1574 {
1575 struct kioctx *ctx;
1576 long ret = 0;
1577 int i = 0;
1578 struct blk_plug plug;
1579
1580 if (unlikely(nr < 0))
1581 return -EINVAL;
1582
1583 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1584 nr = LONG_MAX/sizeof(*iocbpp);
1585
1586 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1587 return -EFAULT;
1588
1589 ctx = lookup_ioctx(ctx_id);
1590 if (unlikely(!ctx)) {
1591 pr_debug("EINVAL: invalid context id\n");
1592 return -EINVAL;
1593 }
1594
1595 blk_start_plug(&plug);
1596
1597 /*
1598 * AKPM: should this return a partial result if some of the IOs were
1599 * successfully submitted?
1600 */
1601 for (i=0; i<nr; i++) {
1602 struct iocb __user *user_iocb;
1603 struct iocb tmp;
1604
1605 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1606 ret = -EFAULT;
1607 break;
1608 }
1609
1610 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1611 ret = -EFAULT;
1612 break;
1613 }
1614
1615 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1616 if (ret)
1617 break;
1618 }
1619 blk_finish_plug(&plug);
1620
1621 percpu_ref_put(&ctx->users);
1622 return i ? i : ret;
1623 }
1624
1625 /* sys_io_submit:
1626 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1627 * the number of iocbs queued. May return -EINVAL if the aio_context
1628 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1629 * *iocbpp[0] is not properly initialized, if the operation specified
1630 * is invalid for the file descriptor in the iocb. May fail with
1631 * -EFAULT if any of the data structures point to invalid data. May
1632 * fail with -EBADF if the file descriptor specified in the first
1633 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1634 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1635 * fail with -ENOSYS if not implemented.
1636 */
1637 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1638 struct iocb __user * __user *, iocbpp)
1639 {
1640 return do_io_submit(ctx_id, nr, iocbpp, 0);
1641 }
1642
1643 /* lookup_kiocb
1644 * Finds a given iocb for cancellation.
1645 */
1646 static struct aio_kiocb *
1647 lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
1648 {
1649 struct aio_kiocb *kiocb;
1650
1651 assert_spin_locked(&ctx->ctx_lock);
1652
1653 if (key != KIOCB_KEY)
1654 return NULL;
1655
1656 /* TODO: use a hash or array, this sucks. */
1657 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
1658 if (kiocb->ki_user_iocb == iocb)
1659 return kiocb;
1660 }
1661 return NULL;
1662 }
1663
1664 /* sys_io_cancel:
1665 * Attempts to cancel an iocb previously passed to io_submit. If
1666 * the operation is successfully cancelled, the resulting event is
1667 * copied into the memory pointed to by result without being placed
1668 * into the completion queue and 0 is returned. May fail with
1669 * -EFAULT if any of the data structures pointed to are invalid.
1670 * May fail with -EINVAL if aio_context specified by ctx_id is
1671 * invalid. May fail with -EAGAIN if the iocb specified was not
1672 * cancelled. Will fail with -ENOSYS if not implemented.
1673 */
1674 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1675 struct io_event __user *, result)
1676 {
1677 struct kioctx *ctx;
1678 struct aio_kiocb *kiocb;
1679 u32 key;
1680 int ret;
1681
1682 ret = get_user(key, &iocb->aio_key);
1683 if (unlikely(ret))
1684 return -EFAULT;
1685
1686 ctx = lookup_ioctx(ctx_id);
1687 if (unlikely(!ctx))
1688 return -EINVAL;
1689
1690 spin_lock_irq(&ctx->ctx_lock);
1691
1692 kiocb = lookup_kiocb(ctx, iocb, key);
1693 if (kiocb)
1694 ret = kiocb_cancel(kiocb);
1695 else
1696 ret = -EINVAL;
1697
1698 spin_unlock_irq(&ctx->ctx_lock);
1699
1700 if (!ret) {
1701 /*
1702 * The result argument is no longer used - the io_event is
1703 * always delivered via the ring buffer. -EINPROGRESS indicates
1704 * cancellation is progress:
1705 */
1706 ret = -EINPROGRESS;
1707 }
1708
1709 percpu_ref_put(&ctx->users);
1710
1711 return ret;
1712 }
1713
1714 /* io_getevents:
1715 * Attempts to read at least min_nr events and up to nr events from
1716 * the completion queue for the aio_context specified by ctx_id. If
1717 * it succeeds, the number of read events is returned. May fail with
1718 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1719 * out of range, if timeout is out of range. May fail with -EFAULT
1720 * if any of the memory specified is invalid. May return 0 or
1721 * < min_nr if the timeout specified by timeout has elapsed
1722 * before sufficient events are available, where timeout == NULL
1723 * specifies an infinite timeout. Note that the timeout pointed to by
1724 * timeout is relative. Will fail with -ENOSYS if not implemented.
1725 */
1726 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1727 long, min_nr,
1728 long, nr,
1729 struct io_event __user *, events,
1730 struct timespec __user *, timeout)
1731 {
1732 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1733 long ret = -EINVAL;
1734
1735 if (likely(ioctx)) {
1736 if (likely(min_nr <= nr && min_nr >= 0))
1737 ret = read_events(ioctx, min_nr, nr, events, timeout);
1738 percpu_ref_put(&ioctx->users);
1739 }
1740 return ret;
1741 }