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