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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 struct dentry *root = mount_pseudo(fs_type, "aio:", NULL, &ops,
243 AIO_RING_MAGIC);
244
245 if (!IS_ERR(root))
246 root->d_sb->s_iflags |= SB_I_NOEXEC;
247 return root;
248 }
249
250 /* aio_setup
251 * Creates the slab caches used by the aio routines, panic on
252 * failure as this is done early during the boot sequence.
253 */
254 static int __init aio_setup(void)
255 {
256 static struct file_system_type aio_fs = {
257 .name = "aio",
258 .mount = aio_mount,
259 .kill_sb = kill_anon_super,
260 };
261 aio_mnt = kern_mount(&aio_fs);
262 if (IS_ERR(aio_mnt))
263 panic("Failed to create aio fs mount.");
264
265 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
266 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
267
268 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
269
270 return 0;
271 }
272 __initcall(aio_setup);
273
274 static void put_aio_ring_file(struct kioctx *ctx)
275 {
276 struct file *aio_ring_file = ctx->aio_ring_file;
277 struct address_space *i_mapping;
278
279 if (aio_ring_file) {
280 truncate_setsize(aio_ring_file->f_inode, 0);
281
282 /* Prevent further access to the kioctx from migratepages */
283 i_mapping = aio_ring_file->f_inode->i_mapping;
284 spin_lock(&i_mapping->private_lock);
285 i_mapping->private_data = NULL;
286 ctx->aio_ring_file = NULL;
287 spin_unlock(&i_mapping->private_lock);
288
289 fput(aio_ring_file);
290 }
291 }
292
293 static void aio_free_ring(struct kioctx *ctx)
294 {
295 int i;
296
297 /* Disconnect the kiotx from the ring file. This prevents future
298 * accesses to the kioctx from page migration.
299 */
300 put_aio_ring_file(ctx);
301
302 for (i = 0; i < ctx->nr_pages; i++) {
303 struct page *page;
304 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
305 page_count(ctx->ring_pages[i]));
306 page = ctx->ring_pages[i];
307 if (!page)
308 continue;
309 ctx->ring_pages[i] = NULL;
310 put_page(page);
311 }
312
313 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
314 kfree(ctx->ring_pages);
315 ctx->ring_pages = NULL;
316 }
317 }
318
319 static int aio_ring_mremap(struct vm_area_struct *vma)
320 {
321 struct file *file = vma->vm_file;
322 struct mm_struct *mm = vma->vm_mm;
323 struct kioctx_table *table;
324 int i, res = -EINVAL;
325
326 spin_lock(&mm->ioctx_lock);
327 rcu_read_lock();
328 table = rcu_dereference(mm->ioctx_table);
329 for (i = 0; i < table->nr; i++) {
330 struct kioctx *ctx;
331
332 ctx = table->table[i];
333 if (ctx && ctx->aio_ring_file == file) {
334 if (!atomic_read(&ctx->dead)) {
335 ctx->user_id = ctx->mmap_base = vma->vm_start;
336 res = 0;
337 }
338 break;
339 }
340 }
341
342 rcu_read_unlock();
343 spin_unlock(&mm->ioctx_lock);
344 return res;
345 }
346
347 static const struct vm_operations_struct aio_ring_vm_ops = {
348 .mremap = aio_ring_mremap,
349 #if IS_ENABLED(CONFIG_MMU)
350 .fault = filemap_fault,
351 .map_pages = filemap_map_pages,
352 .page_mkwrite = filemap_page_mkwrite,
353 #endif
354 };
355
356 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
357 {
358 vma->vm_flags |= VM_DONTEXPAND;
359 vma->vm_ops = &aio_ring_vm_ops;
360 return 0;
361 }
362
363 static const struct file_operations aio_ring_fops = {
364 .mmap = aio_ring_mmap,
365 };
366
367 #if IS_ENABLED(CONFIG_MIGRATION)
368 static int aio_migratepage(struct address_space *mapping, struct page *new,
369 struct page *old, enum migrate_mode mode)
370 {
371 struct kioctx *ctx;
372 unsigned long flags;
373 pgoff_t idx;
374 int rc;
375
376 rc = 0;
377
378 /* mapping->private_lock here protects against the kioctx teardown. */
379 spin_lock(&mapping->private_lock);
380 ctx = mapping->private_data;
381 if (!ctx) {
382 rc = -EINVAL;
383 goto out;
384 }
385
386 /* The ring_lock mutex. The prevents aio_read_events() from writing
387 * to the ring's head, and prevents page migration from mucking in
388 * a partially initialized kiotx.
389 */
390 if (!mutex_trylock(&ctx->ring_lock)) {
391 rc = -EAGAIN;
392 goto out;
393 }
394
395 idx = old->index;
396 if (idx < (pgoff_t)ctx->nr_pages) {
397 /* Make sure the old page hasn't already been changed */
398 if (ctx->ring_pages[idx] != old)
399 rc = -EAGAIN;
400 } else
401 rc = -EINVAL;
402
403 if (rc != 0)
404 goto out_unlock;
405
406 /* Writeback must be complete */
407 BUG_ON(PageWriteback(old));
408 get_page(new);
409
410 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
411 if (rc != MIGRATEPAGE_SUCCESS) {
412 put_page(new);
413 goto out_unlock;
414 }
415
416 /* Take completion_lock to prevent other writes to the ring buffer
417 * while the old page is copied to the new. This prevents new
418 * events from being lost.
419 */
420 spin_lock_irqsave(&ctx->completion_lock, flags);
421 migrate_page_copy(new, old);
422 BUG_ON(ctx->ring_pages[idx] != old);
423 ctx->ring_pages[idx] = new;
424 spin_unlock_irqrestore(&ctx->completion_lock, flags);
425
426 /* The old page is no longer accessible. */
427 put_page(old);
428
429 out_unlock:
430 mutex_unlock(&ctx->ring_lock);
431 out:
432 spin_unlock(&mapping->private_lock);
433 return rc;
434 }
435 #endif
436
437 static const struct address_space_operations aio_ctx_aops = {
438 .set_page_dirty = __set_page_dirty_no_writeback,
439 #if IS_ENABLED(CONFIG_MIGRATION)
440 .migratepage = aio_migratepage,
441 #endif
442 };
443
444 static int aio_setup_ring(struct kioctx *ctx)
445 {
446 struct aio_ring *ring;
447 unsigned nr_events = ctx->max_reqs;
448 struct mm_struct *mm = current->mm;
449 unsigned long size, unused;
450 int nr_pages;
451 int i;
452 struct file *file;
453
454 /* Compensate for the ring buffer's head/tail overlap entry */
455 nr_events += 2; /* 1 is required, 2 for good luck */
456
457 size = sizeof(struct aio_ring);
458 size += sizeof(struct io_event) * nr_events;
459
460 nr_pages = PFN_UP(size);
461 if (nr_pages < 0)
462 return -EINVAL;
463
464 file = aio_private_file(ctx, nr_pages);
465 if (IS_ERR(file)) {
466 ctx->aio_ring_file = NULL;
467 return -ENOMEM;
468 }
469
470 ctx->aio_ring_file = file;
471 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
472 / sizeof(struct io_event);
473
474 ctx->ring_pages = ctx->internal_pages;
475 if (nr_pages > AIO_RING_PAGES) {
476 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
477 GFP_KERNEL);
478 if (!ctx->ring_pages) {
479 put_aio_ring_file(ctx);
480 return -ENOMEM;
481 }
482 }
483
484 for (i = 0; i < nr_pages; i++) {
485 struct page *page;
486 page = find_or_create_page(file->f_inode->i_mapping,
487 i, GFP_HIGHUSER | __GFP_ZERO);
488 if (!page)
489 break;
490 pr_debug("pid(%d) page[%d]->count=%d\n",
491 current->pid, i, page_count(page));
492 SetPageUptodate(page);
493 unlock_page(page);
494
495 ctx->ring_pages[i] = page;
496 }
497 ctx->nr_pages = i;
498
499 if (unlikely(i != nr_pages)) {
500 aio_free_ring(ctx);
501 return -ENOMEM;
502 }
503
504 ctx->mmap_size = nr_pages * PAGE_SIZE;
505 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
506
507 if (down_write_killable(&mm->mmap_sem)) {
508 ctx->mmap_size = 0;
509 aio_free_ring(ctx);
510 return -EINTR;
511 }
512
513 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
514 PROT_READ | PROT_WRITE,
515 MAP_SHARED, 0, &unused);
516 up_write(&mm->mmap_sem);
517 if (IS_ERR((void *)ctx->mmap_base)) {
518 ctx->mmap_size = 0;
519 aio_free_ring(ctx);
520 return -ENOMEM;
521 }
522
523 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
524
525 ctx->user_id = ctx->mmap_base;
526 ctx->nr_events = nr_events; /* trusted copy */
527
528 ring = kmap_atomic(ctx->ring_pages[0]);
529 ring->nr = nr_events; /* user copy */
530 ring->id = ~0U;
531 ring->head = ring->tail = 0;
532 ring->magic = AIO_RING_MAGIC;
533 ring->compat_features = AIO_RING_COMPAT_FEATURES;
534 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
535 ring->header_length = sizeof(struct aio_ring);
536 kunmap_atomic(ring);
537 flush_dcache_page(ctx->ring_pages[0]);
538
539 return 0;
540 }
541
542 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
543 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
544 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
545
546 void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
547 {
548 struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
549 struct kioctx *ctx = req->ki_ctx;
550 unsigned long flags;
551
552 spin_lock_irqsave(&ctx->ctx_lock, flags);
553
554 if (!req->ki_list.next)
555 list_add(&req->ki_list, &ctx->active_reqs);
556
557 req->ki_cancel = cancel;
558
559 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
560 }
561 EXPORT_SYMBOL(kiocb_set_cancel_fn);
562
563 static int kiocb_cancel(struct aio_kiocb *kiocb)
564 {
565 kiocb_cancel_fn *old, *cancel;
566
567 /*
568 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
569 * actually has a cancel function, hence the cmpxchg()
570 */
571
572 cancel = ACCESS_ONCE(kiocb->ki_cancel);
573 do {
574 if (!cancel || cancel == KIOCB_CANCELLED)
575 return -EINVAL;
576
577 old = cancel;
578 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
579 } while (cancel != old);
580
581 return cancel(&kiocb->common);
582 }
583
584 static void free_ioctx(struct work_struct *work)
585 {
586 struct kioctx *ctx = container_of(work, struct kioctx, free_work);
587
588 pr_debug("freeing %p\n", ctx);
589
590 aio_free_ring(ctx);
591 free_percpu(ctx->cpu);
592 percpu_ref_exit(&ctx->reqs);
593 percpu_ref_exit(&ctx->users);
594 kmem_cache_free(kioctx_cachep, ctx);
595 }
596
597 static void free_ioctx_reqs(struct percpu_ref *ref)
598 {
599 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
600
601 /* At this point we know that there are no any in-flight requests */
602 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
603 complete(&ctx->rq_wait->comp);
604
605 INIT_WORK(&ctx->free_work, free_ioctx);
606 schedule_work(&ctx->free_work);
607 }
608
609 /*
610 * When this function runs, the kioctx has been removed from the "hash table"
611 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
612 * now it's safe to cancel any that need to be.
613 */
614 static void free_ioctx_users(struct percpu_ref *ref)
615 {
616 struct kioctx *ctx = container_of(ref, struct kioctx, users);
617 struct aio_kiocb *req;
618
619 spin_lock_irq(&ctx->ctx_lock);
620
621 while (!list_empty(&ctx->active_reqs)) {
622 req = list_first_entry(&ctx->active_reqs,
623 struct aio_kiocb, ki_list);
624
625 list_del_init(&req->ki_list);
626 kiocb_cancel(req);
627 }
628
629 spin_unlock_irq(&ctx->ctx_lock);
630
631 percpu_ref_kill(&ctx->reqs);
632 percpu_ref_put(&ctx->reqs);
633 }
634
635 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
636 {
637 unsigned i, new_nr;
638 struct kioctx_table *table, *old;
639 struct aio_ring *ring;
640
641 spin_lock(&mm->ioctx_lock);
642 table = rcu_dereference_raw(mm->ioctx_table);
643
644 while (1) {
645 if (table)
646 for (i = 0; i < table->nr; i++)
647 if (!table->table[i]) {
648 ctx->id = i;
649 table->table[i] = ctx;
650 spin_unlock(&mm->ioctx_lock);
651
652 /* While kioctx setup is in progress,
653 * we are protected from page migration
654 * changes ring_pages by ->ring_lock.
655 */
656 ring = kmap_atomic(ctx->ring_pages[0]);
657 ring->id = ctx->id;
658 kunmap_atomic(ring);
659 return 0;
660 }
661
662 new_nr = (table ? table->nr : 1) * 4;
663 spin_unlock(&mm->ioctx_lock);
664
665 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
666 new_nr, GFP_KERNEL);
667 if (!table)
668 return -ENOMEM;
669
670 table->nr = new_nr;
671
672 spin_lock(&mm->ioctx_lock);
673 old = rcu_dereference_raw(mm->ioctx_table);
674
675 if (!old) {
676 rcu_assign_pointer(mm->ioctx_table, table);
677 } else if (table->nr > old->nr) {
678 memcpy(table->table, old->table,
679 old->nr * sizeof(struct kioctx *));
680
681 rcu_assign_pointer(mm->ioctx_table, table);
682 kfree_rcu(old, rcu);
683 } else {
684 kfree(table);
685 table = old;
686 }
687 }
688 }
689
690 static void aio_nr_sub(unsigned nr)
691 {
692 spin_lock(&aio_nr_lock);
693 if (WARN_ON(aio_nr - nr > aio_nr))
694 aio_nr = 0;
695 else
696 aio_nr -= nr;
697 spin_unlock(&aio_nr_lock);
698 }
699
700 /* ioctx_alloc
701 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
702 */
703 static struct kioctx *ioctx_alloc(unsigned nr_events)
704 {
705 struct mm_struct *mm = current->mm;
706 struct kioctx *ctx;
707 int err = -ENOMEM;
708
709 /*
710 * We keep track of the number of available ringbuffer slots, to prevent
711 * overflow (reqs_available), and we also use percpu counters for this.
712 *
713 * So since up to half the slots might be on other cpu's percpu counters
714 * and unavailable, double nr_events so userspace sees what they
715 * expected: additionally, we move req_batch slots to/from percpu
716 * counters at a time, so make sure that isn't 0:
717 */
718 nr_events = max(nr_events, num_possible_cpus() * 4);
719 nr_events *= 2;
720
721 /* Prevent overflows */
722 if (nr_events > (0x10000000U / sizeof(struct io_event))) {
723 pr_debug("ENOMEM: nr_events too high\n");
724 return ERR_PTR(-EINVAL);
725 }
726
727 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
728 return ERR_PTR(-EAGAIN);
729
730 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
731 if (!ctx)
732 return ERR_PTR(-ENOMEM);
733
734 ctx->max_reqs = nr_events;
735
736 spin_lock_init(&ctx->ctx_lock);
737 spin_lock_init(&ctx->completion_lock);
738 mutex_init(&ctx->ring_lock);
739 /* Protect against page migration throughout kiotx setup by keeping
740 * the ring_lock mutex held until setup is complete. */
741 mutex_lock(&ctx->ring_lock);
742 init_waitqueue_head(&ctx->wait);
743
744 INIT_LIST_HEAD(&ctx->active_reqs);
745
746 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
747 goto err;
748
749 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
750 goto err;
751
752 ctx->cpu = alloc_percpu(struct kioctx_cpu);
753 if (!ctx->cpu)
754 goto err;
755
756 err = aio_setup_ring(ctx);
757 if (err < 0)
758 goto err;
759
760 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
761 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
762 if (ctx->req_batch < 1)
763 ctx->req_batch = 1;
764
765 /* limit the number of system wide aios */
766 spin_lock(&aio_nr_lock);
767 if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
768 aio_nr + nr_events < aio_nr) {
769 spin_unlock(&aio_nr_lock);
770 err = -EAGAIN;
771 goto err_ctx;
772 }
773 aio_nr += ctx->max_reqs;
774 spin_unlock(&aio_nr_lock);
775
776 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
777 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
778
779 err = ioctx_add_table(ctx, mm);
780 if (err)
781 goto err_cleanup;
782
783 /* Release the ring_lock mutex now that all setup is complete. */
784 mutex_unlock(&ctx->ring_lock);
785
786 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
787 ctx, ctx->user_id, mm, ctx->nr_events);
788 return ctx;
789
790 err_cleanup:
791 aio_nr_sub(ctx->max_reqs);
792 err_ctx:
793 atomic_set(&ctx->dead, 1);
794 if (ctx->mmap_size)
795 vm_munmap(ctx->mmap_base, ctx->mmap_size);
796 aio_free_ring(ctx);
797 err:
798 mutex_unlock(&ctx->ring_lock);
799 free_percpu(ctx->cpu);
800 percpu_ref_exit(&ctx->reqs);
801 percpu_ref_exit(&ctx->users);
802 kmem_cache_free(kioctx_cachep, ctx);
803 pr_debug("error allocating ioctx %d\n", err);
804 return ERR_PTR(err);
805 }
806
807 /* kill_ioctx
808 * Cancels all outstanding aio requests on an aio context. Used
809 * when the processes owning a context have all exited to encourage
810 * the rapid destruction of the kioctx.
811 */
812 static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
813 struct ctx_rq_wait *wait)
814 {
815 struct kioctx_table *table;
816
817 spin_lock(&mm->ioctx_lock);
818 if (atomic_xchg(&ctx->dead, 1)) {
819 spin_unlock(&mm->ioctx_lock);
820 return -EINVAL;
821 }
822
823 table = rcu_dereference_raw(mm->ioctx_table);
824 WARN_ON(ctx != table->table[ctx->id]);
825 table->table[ctx->id] = NULL;
826 spin_unlock(&mm->ioctx_lock);
827
828 /* percpu_ref_kill() will do the necessary call_rcu() */
829 wake_up_all(&ctx->wait);
830
831 /*
832 * It'd be more correct to do this in free_ioctx(), after all
833 * the outstanding kiocbs have finished - but by then io_destroy
834 * has already returned, so io_setup() could potentially return
835 * -EAGAIN with no ioctxs actually in use (as far as userspace
836 * could tell).
837 */
838 aio_nr_sub(ctx->max_reqs);
839
840 if (ctx->mmap_size)
841 vm_munmap(ctx->mmap_base, ctx->mmap_size);
842
843 ctx->rq_wait = wait;
844 percpu_ref_kill(&ctx->users);
845 return 0;
846 }
847
848 /*
849 * exit_aio: called when the last user of mm goes away. At this point, there is
850 * no way for any new requests to be submited or any of the io_* syscalls to be
851 * called on the context.
852 *
853 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
854 * them.
855 */
856 void exit_aio(struct mm_struct *mm)
857 {
858 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
859 struct ctx_rq_wait wait;
860 int i, skipped;
861
862 if (!table)
863 return;
864
865 atomic_set(&wait.count, table->nr);
866 init_completion(&wait.comp);
867
868 skipped = 0;
869 for (i = 0; i < table->nr; ++i) {
870 struct kioctx *ctx = table->table[i];
871
872 if (!ctx) {
873 skipped++;
874 continue;
875 }
876
877 /*
878 * We don't need to bother with munmap() here - exit_mmap(mm)
879 * is coming and it'll unmap everything. And we simply can't,
880 * this is not necessarily our ->mm.
881 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
882 * that it needs to unmap the area, just set it to 0.
883 */
884 ctx->mmap_size = 0;
885 kill_ioctx(mm, ctx, &wait);
886 }
887
888 if (!atomic_sub_and_test(skipped, &wait.count)) {
889 /* Wait until all IO for the context are done. */
890 wait_for_completion(&wait.comp);
891 }
892
893 RCU_INIT_POINTER(mm->ioctx_table, NULL);
894 kfree(table);
895 }
896
897 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
898 {
899 struct kioctx_cpu *kcpu;
900 unsigned long flags;
901
902 local_irq_save(flags);
903 kcpu = this_cpu_ptr(ctx->cpu);
904 kcpu->reqs_available += nr;
905
906 while (kcpu->reqs_available >= ctx->req_batch * 2) {
907 kcpu->reqs_available -= ctx->req_batch;
908 atomic_add(ctx->req_batch, &ctx->reqs_available);
909 }
910
911 local_irq_restore(flags);
912 }
913
914 static bool get_reqs_available(struct kioctx *ctx)
915 {
916 struct kioctx_cpu *kcpu;
917 bool ret = false;
918 unsigned long flags;
919
920 local_irq_save(flags);
921 kcpu = this_cpu_ptr(ctx->cpu);
922 if (!kcpu->reqs_available) {
923 int old, avail = atomic_read(&ctx->reqs_available);
924
925 do {
926 if (avail < ctx->req_batch)
927 goto out;
928
929 old = avail;
930 avail = atomic_cmpxchg(&ctx->reqs_available,
931 avail, avail - ctx->req_batch);
932 } while (avail != old);
933
934 kcpu->reqs_available += ctx->req_batch;
935 }
936
937 ret = true;
938 kcpu->reqs_available--;
939 out:
940 local_irq_restore(flags);
941 return ret;
942 }
943
944 /* refill_reqs_available
945 * Updates the reqs_available reference counts used for tracking the
946 * number of free slots in the completion ring. This can be called
947 * from aio_complete() (to optimistically update reqs_available) or
948 * from aio_get_req() (the we're out of events case). It must be
949 * called holding ctx->completion_lock.
950 */
951 static void refill_reqs_available(struct kioctx *ctx, unsigned head,
952 unsigned tail)
953 {
954 unsigned events_in_ring, completed;
955
956 /* Clamp head since userland can write to it. */
957 head %= ctx->nr_events;
958 if (head <= tail)
959 events_in_ring = tail - head;
960 else
961 events_in_ring = ctx->nr_events - (head - tail);
962
963 completed = ctx->completed_events;
964 if (events_in_ring < completed)
965 completed -= events_in_ring;
966 else
967 completed = 0;
968
969 if (!completed)
970 return;
971
972 ctx->completed_events -= completed;
973 put_reqs_available(ctx, completed);
974 }
975
976 /* user_refill_reqs_available
977 * Called to refill reqs_available when aio_get_req() encounters an
978 * out of space in the completion ring.
979 */
980 static void user_refill_reqs_available(struct kioctx *ctx)
981 {
982 spin_lock_irq(&ctx->completion_lock);
983 if (ctx->completed_events) {
984 struct aio_ring *ring;
985 unsigned head;
986
987 /* Access of ring->head may race with aio_read_events_ring()
988 * here, but that's okay since whether we read the old version
989 * or the new version, and either will be valid. The important
990 * part is that head cannot pass tail since we prevent
991 * aio_complete() from updating tail by holding
992 * ctx->completion_lock. Even if head is invalid, the check
993 * against ctx->completed_events below will make sure we do the
994 * safe/right thing.
995 */
996 ring = kmap_atomic(ctx->ring_pages[0]);
997 head = ring->head;
998 kunmap_atomic(ring);
999
1000 refill_reqs_available(ctx, head, ctx->tail);
1001 }
1002
1003 spin_unlock_irq(&ctx->completion_lock);
1004 }
1005
1006 /* aio_get_req
1007 * Allocate a slot for an aio request.
1008 * Returns NULL if no requests are free.
1009 */
1010 static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1011 {
1012 struct aio_kiocb *req;
1013
1014 if (!get_reqs_available(ctx)) {
1015 user_refill_reqs_available(ctx);
1016 if (!get_reqs_available(ctx))
1017 return NULL;
1018 }
1019
1020 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
1021 if (unlikely(!req))
1022 goto out_put;
1023
1024 percpu_ref_get(&ctx->reqs);
1025
1026 req->ki_ctx = ctx;
1027 return req;
1028 out_put:
1029 put_reqs_available(ctx, 1);
1030 return NULL;
1031 }
1032
1033 static void kiocb_free(struct aio_kiocb *req)
1034 {
1035 if (req->common.ki_filp)
1036 fput(req->common.ki_filp);
1037 if (req->ki_eventfd != NULL)
1038 eventfd_ctx_put(req->ki_eventfd);
1039 kmem_cache_free(kiocb_cachep, req);
1040 }
1041
1042 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1043 {
1044 struct aio_ring __user *ring = (void __user *)ctx_id;
1045 struct mm_struct *mm = current->mm;
1046 struct kioctx *ctx, *ret = NULL;
1047 struct kioctx_table *table;
1048 unsigned id;
1049
1050 if (get_user(id, &ring->id))
1051 return NULL;
1052
1053 rcu_read_lock();
1054 table = rcu_dereference(mm->ioctx_table);
1055
1056 if (!table || id >= table->nr)
1057 goto out;
1058
1059 ctx = table->table[id];
1060 if (ctx && ctx->user_id == ctx_id) {
1061 percpu_ref_get(&ctx->users);
1062 ret = ctx;
1063 }
1064 out:
1065 rcu_read_unlock();
1066 return ret;
1067 }
1068
1069 /* aio_complete
1070 * Called when the io request on the given iocb is complete.
1071 */
1072 static void aio_complete(struct kiocb *kiocb, long res, long res2)
1073 {
1074 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
1075 struct kioctx *ctx = iocb->ki_ctx;
1076 struct aio_ring *ring;
1077 struct io_event *ev_page, *event;
1078 unsigned tail, pos, head;
1079 unsigned long flags;
1080
1081 /*
1082 * Special case handling for sync iocbs:
1083 * - events go directly into the iocb for fast handling
1084 * - the sync task with the iocb in its stack holds the single iocb
1085 * ref, no other paths have a way to get another ref
1086 * - the sync task helpfully left a reference to itself in the iocb
1087 */
1088 BUG_ON(is_sync_kiocb(kiocb));
1089
1090 if (iocb->ki_list.next) {
1091 unsigned long flags;
1092
1093 spin_lock_irqsave(&ctx->ctx_lock, flags);
1094 list_del(&iocb->ki_list);
1095 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1096 }
1097
1098 /*
1099 * Add a completion event to the ring buffer. Must be done holding
1100 * ctx->completion_lock to prevent other code from messing with the tail
1101 * pointer since we might be called from irq context.
1102 */
1103 spin_lock_irqsave(&ctx->completion_lock, flags);
1104
1105 tail = ctx->tail;
1106 pos = tail + AIO_EVENTS_OFFSET;
1107
1108 if (++tail >= ctx->nr_events)
1109 tail = 0;
1110
1111 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1112 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1113
1114 event->obj = (u64)(unsigned long)iocb->ki_user_iocb;
1115 event->data = iocb->ki_user_data;
1116 event->res = res;
1117 event->res2 = res2;
1118
1119 kunmap_atomic(ev_page);
1120 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1121
1122 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
1123 ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data,
1124 res, res2);
1125
1126 /* after flagging the request as done, we
1127 * must never even look at it again
1128 */
1129 smp_wmb(); /* make event visible before updating tail */
1130
1131 ctx->tail = tail;
1132
1133 ring = kmap_atomic(ctx->ring_pages[0]);
1134 head = ring->head;
1135 ring->tail = tail;
1136 kunmap_atomic(ring);
1137 flush_dcache_page(ctx->ring_pages[0]);
1138
1139 ctx->completed_events++;
1140 if (ctx->completed_events > 1)
1141 refill_reqs_available(ctx, head, tail);
1142 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1143
1144 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1145
1146 /*
1147 * Check if the user asked us to deliver the result through an
1148 * eventfd. The eventfd_signal() function is safe to be called
1149 * from IRQ context.
1150 */
1151 if (iocb->ki_eventfd != NULL)
1152 eventfd_signal(iocb->ki_eventfd, 1);
1153
1154 /* everything turned out well, dispose of the aiocb. */
1155 kiocb_free(iocb);
1156
1157 /*
1158 * We have to order our ring_info tail store above and test
1159 * of the wait list below outside the wait lock. This is
1160 * like in wake_up_bit() where clearing a bit has to be
1161 * ordered with the unlocked test.
1162 */
1163 smp_mb();
1164
1165 if (waitqueue_active(&ctx->wait))
1166 wake_up(&ctx->wait);
1167
1168 percpu_ref_put(&ctx->reqs);
1169 }
1170
1171 /* aio_read_events_ring
1172 * Pull an event off of the ioctx's event ring. Returns the number of
1173 * events fetched
1174 */
1175 static long aio_read_events_ring(struct kioctx *ctx,
1176 struct io_event __user *event, long nr)
1177 {
1178 struct aio_ring *ring;
1179 unsigned head, tail, pos;
1180 long ret = 0;
1181 int copy_ret;
1182
1183 /*
1184 * The mutex can block and wake us up and that will cause
1185 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1186 * and repeat. This should be rare enough that it doesn't cause
1187 * peformance issues. See the comment in read_events() for more detail.
1188 */
1189 sched_annotate_sleep();
1190 mutex_lock(&ctx->ring_lock);
1191
1192 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1193 ring = kmap_atomic(ctx->ring_pages[0]);
1194 head = ring->head;
1195 tail = ring->tail;
1196 kunmap_atomic(ring);
1197
1198 /*
1199 * Ensure that once we've read the current tail pointer, that
1200 * we also see the events that were stored up to the tail.
1201 */
1202 smp_rmb();
1203
1204 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1205
1206 if (head == tail)
1207 goto out;
1208
1209 head %= ctx->nr_events;
1210 tail %= ctx->nr_events;
1211
1212 while (ret < nr) {
1213 long avail;
1214 struct io_event *ev;
1215 struct page *page;
1216
1217 avail = (head <= tail ? tail : ctx->nr_events) - head;
1218 if (head == tail)
1219 break;
1220
1221 avail = min(avail, nr - ret);
1222 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
1223 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
1224
1225 pos = head + AIO_EVENTS_OFFSET;
1226 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1227 pos %= AIO_EVENTS_PER_PAGE;
1228
1229 ev = kmap(page);
1230 copy_ret = copy_to_user(event + ret, ev + pos,
1231 sizeof(*ev) * avail);
1232 kunmap(page);
1233
1234 if (unlikely(copy_ret)) {
1235 ret = -EFAULT;
1236 goto out;
1237 }
1238
1239 ret += avail;
1240 head += avail;
1241 head %= ctx->nr_events;
1242 }
1243
1244 ring = kmap_atomic(ctx->ring_pages[0]);
1245 ring->head = head;
1246 kunmap_atomic(ring);
1247 flush_dcache_page(ctx->ring_pages[0]);
1248
1249 pr_debug("%li h%u t%u\n", ret, head, tail);
1250 out:
1251 mutex_unlock(&ctx->ring_lock);
1252
1253 return ret;
1254 }
1255
1256 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1257 struct io_event __user *event, long *i)
1258 {
1259 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1260
1261 if (ret > 0)
1262 *i += ret;
1263
1264 if (unlikely(atomic_read(&ctx->dead)))
1265 ret = -EINVAL;
1266
1267 if (!*i)
1268 *i = ret;
1269
1270 return ret < 0 || *i >= min_nr;
1271 }
1272
1273 static long read_events(struct kioctx *ctx, long min_nr, long nr,
1274 struct io_event __user *event,
1275 struct timespec __user *timeout)
1276 {
1277 ktime_t until = { .tv64 = KTIME_MAX };
1278 long ret = 0;
1279
1280 if (timeout) {
1281 struct timespec ts;
1282
1283 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1284 return -EFAULT;
1285
1286 until = timespec_to_ktime(ts);
1287 }
1288
1289 /*
1290 * Note that aio_read_events() is being called as the conditional - i.e.
1291 * we're calling it after prepare_to_wait() has set task state to
1292 * TASK_INTERRUPTIBLE.
1293 *
1294 * But aio_read_events() can block, and if it blocks it's going to flip
1295 * the task state back to TASK_RUNNING.
1296 *
1297 * This should be ok, provided it doesn't flip the state back to
1298 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1299 * will only happen if the mutex_lock() call blocks, and we then find
1300 * the ringbuffer empty. So in practice we should be ok, but it's
1301 * something to be aware of when touching this code.
1302 */
1303 if (until.tv64 == 0)
1304 aio_read_events(ctx, min_nr, nr, event, &ret);
1305 else
1306 wait_event_interruptible_hrtimeout(ctx->wait,
1307 aio_read_events(ctx, min_nr, nr, event, &ret),
1308 until);
1309
1310 if (!ret && signal_pending(current))
1311 ret = -EINTR;
1312
1313 return ret;
1314 }
1315
1316 /* sys_io_setup:
1317 * Create an aio_context capable of receiving at least nr_events.
1318 * ctxp must not point to an aio_context that already exists, and
1319 * must be initialized to 0 prior to the call. On successful
1320 * creation of the aio_context, *ctxp is filled in with the resulting
1321 * handle. May fail with -EINVAL if *ctxp is not initialized,
1322 * if the specified nr_events exceeds internal limits. May fail
1323 * with -EAGAIN if the specified nr_events exceeds the user's limit
1324 * of available events. May fail with -ENOMEM if insufficient kernel
1325 * resources are available. May fail with -EFAULT if an invalid
1326 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1327 * implemented.
1328 */
1329 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1330 {
1331 struct kioctx *ioctx = NULL;
1332 unsigned long ctx;
1333 long ret;
1334
1335 ret = get_user(ctx, ctxp);
1336 if (unlikely(ret))
1337 goto out;
1338
1339 ret = -EINVAL;
1340 if (unlikely(ctx || nr_events == 0)) {
1341 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1342 ctx, nr_events);
1343 goto out;
1344 }
1345
1346 ioctx = ioctx_alloc(nr_events);
1347 ret = PTR_ERR(ioctx);
1348 if (!IS_ERR(ioctx)) {
1349 ret = put_user(ioctx->user_id, ctxp);
1350 if (ret)
1351 kill_ioctx(current->mm, ioctx, NULL);
1352 percpu_ref_put(&ioctx->users);
1353 }
1354
1355 out:
1356 return ret;
1357 }
1358
1359 /* sys_io_destroy:
1360 * Destroy the aio_context specified. May cancel any outstanding
1361 * AIOs and block on completion. Will fail with -ENOSYS if not
1362 * implemented. May fail with -EINVAL if the context pointed to
1363 * is invalid.
1364 */
1365 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1366 {
1367 struct kioctx *ioctx = lookup_ioctx(ctx);
1368 if (likely(NULL != ioctx)) {
1369 struct ctx_rq_wait wait;
1370 int ret;
1371
1372 init_completion(&wait.comp);
1373 atomic_set(&wait.count, 1);
1374
1375 /* Pass requests_done to kill_ioctx() where it can be set
1376 * in a thread-safe way. If we try to set it here then we have
1377 * a race condition if two io_destroy() called simultaneously.
1378 */
1379 ret = kill_ioctx(current->mm, ioctx, &wait);
1380 percpu_ref_put(&ioctx->users);
1381
1382 /* Wait until all IO for the context are done. Otherwise kernel
1383 * keep using user-space buffers even if user thinks the context
1384 * is destroyed.
1385 */
1386 if (!ret)
1387 wait_for_completion(&wait.comp);
1388
1389 return ret;
1390 }
1391 pr_debug("EINVAL: invalid context id\n");
1392 return -EINVAL;
1393 }
1394
1395 typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
1396
1397 static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len,
1398 struct iovec **iovec,
1399 bool compat,
1400 struct iov_iter *iter)
1401 {
1402 #ifdef CONFIG_COMPAT
1403 if (compat)
1404 return compat_import_iovec(rw,
1405 (struct compat_iovec __user *)buf,
1406 len, UIO_FASTIOV, iovec, iter);
1407 #endif
1408 return import_iovec(rw, (struct iovec __user *)buf,
1409 len, UIO_FASTIOV, iovec, iter);
1410 }
1411
1412 /*
1413 * aio_run_iocb:
1414 * Performs the initial checks and io submission.
1415 */
1416 static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
1417 char __user *buf, size_t len, bool compat)
1418 {
1419 struct file *file = req->ki_filp;
1420 ssize_t ret;
1421 int rw;
1422 fmode_t mode;
1423 rw_iter_op *iter_op;
1424 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1425 struct iov_iter iter;
1426
1427 switch (opcode) {
1428 case IOCB_CMD_PREAD:
1429 case IOCB_CMD_PREADV:
1430 mode = FMODE_READ;
1431 rw = READ;
1432 iter_op = file->f_op->read_iter;
1433 goto rw_common;
1434
1435 case IOCB_CMD_PWRITE:
1436 case IOCB_CMD_PWRITEV:
1437 mode = FMODE_WRITE;
1438 rw = WRITE;
1439 iter_op = file->f_op->write_iter;
1440 goto rw_common;
1441 rw_common:
1442 if (unlikely(!(file->f_mode & mode)))
1443 return -EBADF;
1444
1445 if (!iter_op)
1446 return -EINVAL;
1447
1448 if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV)
1449 ret = aio_setup_vectored_rw(rw, buf, len,
1450 &iovec, compat, &iter);
1451 else {
1452 ret = import_single_range(rw, buf, len, iovec, &iter);
1453 iovec = NULL;
1454 }
1455 if (!ret)
1456 ret = rw_verify_area(rw, file, &req->ki_pos,
1457 iov_iter_count(&iter));
1458 if (ret < 0) {
1459 kfree(iovec);
1460 return ret;
1461 }
1462
1463 if (rw == WRITE)
1464 file_start_write(file);
1465
1466 ret = iter_op(req, &iter);
1467
1468 if (rw == WRITE)
1469 file_end_write(file);
1470 kfree(iovec);
1471 break;
1472
1473 case IOCB_CMD_FDSYNC:
1474 if (!file->f_op->aio_fsync)
1475 return -EINVAL;
1476
1477 ret = file->f_op->aio_fsync(req, 1);
1478 break;
1479
1480 case IOCB_CMD_FSYNC:
1481 if (!file->f_op->aio_fsync)
1482 return -EINVAL;
1483
1484 ret = file->f_op->aio_fsync(req, 0);
1485 break;
1486
1487 default:
1488 pr_debug("EINVAL: no operation provided\n");
1489 return -EINVAL;
1490 }
1491
1492 if (ret != -EIOCBQUEUED) {
1493 /*
1494 * There's no easy way to restart the syscall since other AIO's
1495 * may be already running. Just fail this IO with EINTR.
1496 */
1497 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1498 ret == -ERESTARTNOHAND ||
1499 ret == -ERESTART_RESTARTBLOCK))
1500 ret = -EINTR;
1501 aio_complete(req, ret, 0);
1502 }
1503
1504 return 0;
1505 }
1506
1507 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1508 struct iocb *iocb, bool compat)
1509 {
1510 struct aio_kiocb *req;
1511 ssize_t ret;
1512
1513 /* enforce forwards compatibility on users */
1514 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1515 pr_debug("EINVAL: reserve field set\n");
1516 return -EINVAL;
1517 }
1518
1519 /* prevent overflows */
1520 if (unlikely(
1521 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1522 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1523 ((ssize_t)iocb->aio_nbytes < 0)
1524 )) {
1525 pr_debug("EINVAL: overflow check\n");
1526 return -EINVAL;
1527 }
1528
1529 req = aio_get_req(ctx);
1530 if (unlikely(!req))
1531 return -EAGAIN;
1532
1533 req->common.ki_filp = fget(iocb->aio_fildes);
1534 if (unlikely(!req->common.ki_filp)) {
1535 ret = -EBADF;
1536 goto out_put_req;
1537 }
1538 req->common.ki_pos = iocb->aio_offset;
1539 req->common.ki_complete = aio_complete;
1540 req->common.ki_flags = iocb_flags(req->common.ki_filp);
1541
1542 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1543 /*
1544 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1545 * instance of the file* now. The file descriptor must be
1546 * an eventfd() fd, and will be signaled for each completed
1547 * event using the eventfd_signal() function.
1548 */
1549 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1550 if (IS_ERR(req->ki_eventfd)) {
1551 ret = PTR_ERR(req->ki_eventfd);
1552 req->ki_eventfd = NULL;
1553 goto out_put_req;
1554 }
1555
1556 req->common.ki_flags |= IOCB_EVENTFD;
1557 }
1558
1559 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1560 if (unlikely(ret)) {
1561 pr_debug("EFAULT: aio_key\n");
1562 goto out_put_req;
1563 }
1564
1565 req->ki_user_iocb = user_iocb;
1566 req->ki_user_data = iocb->aio_data;
1567
1568 ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode,
1569 (char __user *)(unsigned long)iocb->aio_buf,
1570 iocb->aio_nbytes,
1571 compat);
1572 if (ret)
1573 goto out_put_req;
1574
1575 return 0;
1576 out_put_req:
1577 put_reqs_available(ctx, 1);
1578 percpu_ref_put(&ctx->reqs);
1579 kiocb_free(req);
1580 return ret;
1581 }
1582
1583 long do_io_submit(aio_context_t ctx_id, long nr,
1584 struct iocb __user *__user *iocbpp, bool compat)
1585 {
1586 struct kioctx *ctx;
1587 long ret = 0;
1588 int i = 0;
1589 struct blk_plug plug;
1590
1591 if (unlikely(nr < 0))
1592 return -EINVAL;
1593
1594 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1595 nr = LONG_MAX/sizeof(*iocbpp);
1596
1597 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1598 return -EFAULT;
1599
1600 ctx = lookup_ioctx(ctx_id);
1601 if (unlikely(!ctx)) {
1602 pr_debug("EINVAL: invalid context id\n");
1603 return -EINVAL;
1604 }
1605
1606 blk_start_plug(&plug);
1607
1608 /*
1609 * AKPM: should this return a partial result if some of the IOs were
1610 * successfully submitted?
1611 */
1612 for (i=0; i<nr; i++) {
1613 struct iocb __user *user_iocb;
1614 struct iocb tmp;
1615
1616 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1617 ret = -EFAULT;
1618 break;
1619 }
1620
1621 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1622 ret = -EFAULT;
1623 break;
1624 }
1625
1626 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1627 if (ret)
1628 break;
1629 }
1630 blk_finish_plug(&plug);
1631
1632 percpu_ref_put(&ctx->users);
1633 return i ? i : ret;
1634 }
1635
1636 /* sys_io_submit:
1637 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1638 * the number of iocbs queued. May return -EINVAL if the aio_context
1639 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1640 * *iocbpp[0] is not properly initialized, if the operation specified
1641 * is invalid for the file descriptor in the iocb. May fail with
1642 * -EFAULT if any of the data structures point to invalid data. May
1643 * fail with -EBADF if the file descriptor specified in the first
1644 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1645 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1646 * fail with -ENOSYS if not implemented.
1647 */
1648 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1649 struct iocb __user * __user *, iocbpp)
1650 {
1651 return do_io_submit(ctx_id, nr, iocbpp, 0);
1652 }
1653
1654 /* lookup_kiocb
1655 * Finds a given iocb for cancellation.
1656 */
1657 static struct aio_kiocb *
1658 lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
1659 {
1660 struct aio_kiocb *kiocb;
1661
1662 assert_spin_locked(&ctx->ctx_lock);
1663
1664 if (key != KIOCB_KEY)
1665 return NULL;
1666
1667 /* TODO: use a hash or array, this sucks. */
1668 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
1669 if (kiocb->ki_user_iocb == iocb)
1670 return kiocb;
1671 }
1672 return NULL;
1673 }
1674
1675 /* sys_io_cancel:
1676 * Attempts to cancel an iocb previously passed to io_submit. If
1677 * the operation is successfully cancelled, the resulting event is
1678 * copied into the memory pointed to by result without being placed
1679 * into the completion queue and 0 is returned. May fail with
1680 * -EFAULT if any of the data structures pointed to are invalid.
1681 * May fail with -EINVAL if aio_context specified by ctx_id is
1682 * invalid. May fail with -EAGAIN if the iocb specified was not
1683 * cancelled. Will fail with -ENOSYS if not implemented.
1684 */
1685 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1686 struct io_event __user *, result)
1687 {
1688 struct kioctx *ctx;
1689 struct aio_kiocb *kiocb;
1690 u32 key;
1691 int ret;
1692
1693 ret = get_user(key, &iocb->aio_key);
1694 if (unlikely(ret))
1695 return -EFAULT;
1696
1697 ctx = lookup_ioctx(ctx_id);
1698 if (unlikely(!ctx))
1699 return -EINVAL;
1700
1701 spin_lock_irq(&ctx->ctx_lock);
1702
1703 kiocb = lookup_kiocb(ctx, iocb, key);
1704 if (kiocb)
1705 ret = kiocb_cancel(kiocb);
1706 else
1707 ret = -EINVAL;
1708
1709 spin_unlock_irq(&ctx->ctx_lock);
1710
1711 if (!ret) {
1712 /*
1713 * The result argument is no longer used - the io_event is
1714 * always delivered via the ring buffer. -EINPROGRESS indicates
1715 * cancellation is progress:
1716 */
1717 ret = -EINPROGRESS;
1718 }
1719
1720 percpu_ref_put(&ctx->users);
1721
1722 return ret;
1723 }
1724
1725 /* io_getevents:
1726 * Attempts to read at least min_nr events and up to nr events from
1727 * the completion queue for the aio_context specified by ctx_id. If
1728 * it succeeds, the number of read events is returned. May fail with
1729 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1730 * out of range, if timeout is out of range. May fail with -EFAULT
1731 * if any of the memory specified is invalid. May return 0 or
1732 * < min_nr if the timeout specified by timeout has elapsed
1733 * before sufficient events are available, where timeout == NULL
1734 * specifies an infinite timeout. Note that the timeout pointed to by
1735 * timeout is relative. Will fail with -ENOSYS if not implemented.
1736 */
1737 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1738 long, min_nr,
1739 long, nr,
1740 struct io_event __user *, events,
1741 struct timespec __user *, timeout)
1742 {
1743 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1744 long ret = -EINVAL;
1745
1746 if (likely(ioctx)) {
1747 if (likely(min_nr <= nr && min_nr >= 0))
1748 ret = read_events(ioctx, min_nr, nr, events, timeout);
1749 percpu_ref_put(&ioctx->users);
1750 }
1751 return ret;
1752 }