Line data Source code
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 : * Copyright 2018 Christoph Hellwig.
9 : *
10 : * See ../COPYING for licensing terms.
11 : */
12 : #define pr_fmt(fmt) "%s: " fmt, __func__
13 :
14 : #include <linux/kernel.h>
15 : #include <linux/init.h>
16 : #include <linux/errno.h>
17 : #include <linux/time.h>
18 : #include <linux/aio_abi.h>
19 : #include <linux/export.h>
20 : #include <linux/syscalls.h>
21 : #include <linux/backing-dev.h>
22 : #include <linux/refcount.h>
23 : #include <linux/uio.h>
24 :
25 : #include <linux/sched/signal.h>
26 : #include <linux/fs.h>
27 : #include <linux/file.h>
28 : #include <linux/mm.h>
29 : #include <linux/mman.h>
30 : #include <linux/percpu.h>
31 : #include <linux/slab.h>
32 : #include <linux/timer.h>
33 : #include <linux/aio.h>
34 : #include <linux/highmem.h>
35 : #include <linux/workqueue.h>
36 : #include <linux/security.h>
37 : #include <linux/eventfd.h>
38 : #include <linux/blkdev.h>
39 : #include <linux/compat.h>
40 : #include <linux/migrate.h>
41 : #include <linux/ramfs.h>
42 : #include <linux/percpu-refcount.h>
43 : #include <linux/mount.h>
44 : #include <linux/pseudo_fs.h>
45 :
46 : #include <linux/uaccess.h>
47 : #include <linux/nospec.h>
48 :
49 : #include "internal.h"
50 :
51 : #define KIOCB_KEY 0
52 :
53 : #define AIO_RING_MAGIC 0xa10a10a1
54 : #define AIO_RING_COMPAT_FEATURES 1
55 : #define AIO_RING_INCOMPAT_FEATURES 0
56 : struct aio_ring {
57 : unsigned id; /* kernel internal index number */
58 : unsigned nr; /* number of io_events */
59 : unsigned head; /* Written to by userland or under ring_lock
60 : * mutex by aio_read_events_ring(). */
61 : unsigned tail;
62 :
63 : unsigned magic;
64 : unsigned compat_features;
65 : unsigned incompat_features;
66 : unsigned header_length; /* size of aio_ring */
67 :
68 :
69 : struct io_event io_events[];
70 : }; /* 128 bytes + ring size */
71 :
72 : /*
73 : * Plugging is meant to work with larger batches of IOs. If we don't
74 : * have more than the below, then don't bother setting up a plug.
75 : */
76 : #define AIO_PLUG_THRESHOLD 2
77 :
78 : #define AIO_RING_PAGES 8
79 :
80 : struct kioctx_table {
81 : struct rcu_head rcu;
82 : unsigned nr;
83 : struct kioctx __rcu *table[];
84 : };
85 :
86 : struct kioctx_cpu {
87 : unsigned reqs_available;
88 : };
89 :
90 : struct ctx_rq_wait {
91 : struct completion comp;
92 : atomic_t count;
93 : };
94 :
95 : struct kioctx {
96 : struct percpu_ref users;
97 : atomic_t dead;
98 :
99 : struct percpu_ref reqs;
100 :
101 : unsigned long user_id;
102 :
103 : struct __percpu kioctx_cpu *cpu;
104 :
105 : /*
106 : * For percpu reqs_available, number of slots we move to/from global
107 : * counter at a time:
108 : */
109 : unsigned req_batch;
110 : /*
111 : * This is what userspace passed to io_setup(), it's not used for
112 : * anything but counting against the global max_reqs quota.
113 : *
114 : * The real limit is nr_events - 1, which will be larger (see
115 : * aio_setup_ring())
116 : */
117 : unsigned max_reqs;
118 :
119 : /* Size of ringbuffer, in units of struct io_event */
120 : unsigned nr_events;
121 :
122 : unsigned long mmap_base;
123 : unsigned long mmap_size;
124 :
125 : struct page **ring_pages;
126 : long nr_pages;
127 :
128 : struct rcu_work free_rwork; /* see free_ioctx() */
129 :
130 : /*
131 : * signals when all in-flight requests are done
132 : */
133 : struct ctx_rq_wait *rq_wait;
134 :
135 : struct {
136 : /*
137 : * This counts the number of available slots in the ringbuffer,
138 : * so we avoid overflowing it: it's decremented (if positive)
139 : * when allocating a kiocb and incremented when the resulting
140 : * io_event is pulled off the ringbuffer.
141 : *
142 : * We batch accesses to it with a percpu version.
143 : */
144 : atomic_t reqs_available;
145 : } ____cacheline_aligned_in_smp;
146 :
147 : struct {
148 : spinlock_t ctx_lock;
149 : struct list_head active_reqs; /* used for cancellation */
150 : } ____cacheline_aligned_in_smp;
151 :
152 : struct {
153 : struct mutex ring_lock;
154 : wait_queue_head_t wait;
155 : } ____cacheline_aligned_in_smp;
156 :
157 : struct {
158 : unsigned tail;
159 : unsigned completed_events;
160 : spinlock_t completion_lock;
161 : } ____cacheline_aligned_in_smp;
162 :
163 : struct page *internal_pages[AIO_RING_PAGES];
164 : struct file *aio_ring_file;
165 :
166 : unsigned id;
167 : };
168 :
169 : /*
170 : * First field must be the file pointer in all the
171 : * iocb unions! See also 'struct kiocb' in <linux/fs.h>
172 : */
173 : struct fsync_iocb {
174 : struct file *file;
175 : struct work_struct work;
176 : bool datasync;
177 : struct cred *creds;
178 : };
179 :
180 : struct poll_iocb {
181 : struct file *file;
182 : struct wait_queue_head *head;
183 : __poll_t events;
184 : bool cancelled;
185 : bool work_scheduled;
186 : bool work_need_resched;
187 : struct wait_queue_entry wait;
188 : struct work_struct work;
189 : };
190 :
191 : /*
192 : * NOTE! Each of the iocb union members has the file pointer
193 : * as the first entry in their struct definition. So you can
194 : * access the file pointer through any of the sub-structs,
195 : * or directly as just 'ki_filp' in this struct.
196 : */
197 : struct aio_kiocb {
198 : union {
199 : struct file *ki_filp;
200 : struct kiocb rw;
201 : struct fsync_iocb fsync;
202 : struct poll_iocb poll;
203 : };
204 :
205 : struct kioctx *ki_ctx;
206 : kiocb_cancel_fn *ki_cancel;
207 :
208 : struct io_event ki_res;
209 :
210 : struct list_head ki_list; /* the aio core uses this
211 : * for cancellation */
212 : refcount_t ki_refcnt;
213 :
214 : /*
215 : * If the aio_resfd field of the userspace iocb is not zero,
216 : * this is the underlying eventfd context to deliver events to.
217 : */
218 : struct eventfd_ctx *ki_eventfd;
219 : };
220 :
221 : /*------ sysctl variables----*/
222 : static DEFINE_SPINLOCK(aio_nr_lock);
223 : static unsigned long aio_nr; /* current system wide number of aio requests */
224 : static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
225 : /*----end sysctl variables---*/
226 : #ifdef CONFIG_SYSCTL
227 : static struct ctl_table aio_sysctls[] = {
228 : {
229 : .procname = "aio-nr",
230 : .data = &aio_nr,
231 : .maxlen = sizeof(aio_nr),
232 : .mode = 0444,
233 : .proc_handler = proc_doulongvec_minmax,
234 : },
235 : {
236 : .procname = "aio-max-nr",
237 : .data = &aio_max_nr,
238 : .maxlen = sizeof(aio_max_nr),
239 : .mode = 0644,
240 : .proc_handler = proc_doulongvec_minmax,
241 : },
242 : {}
243 : };
244 :
245 1 : static void __init aio_sysctl_init(void)
246 : {
247 1 : register_sysctl_init("fs", aio_sysctls);
248 1 : }
249 : #else
250 : #define aio_sysctl_init() do { } while (0)
251 : #endif
252 :
253 : static struct kmem_cache *kiocb_cachep;
254 : static struct kmem_cache *kioctx_cachep;
255 :
256 : static struct vfsmount *aio_mnt;
257 :
258 : static const struct file_operations aio_ring_fops;
259 : static const struct address_space_operations aio_ctx_aops;
260 :
261 0 : static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
262 : {
263 : struct file *file;
264 0 : struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
265 0 : if (IS_ERR(inode))
266 : return ERR_CAST(inode);
267 :
268 0 : inode->i_mapping->a_ops = &aio_ctx_aops;
269 0 : inode->i_mapping->private_data = ctx;
270 0 : inode->i_size = PAGE_SIZE * nr_pages;
271 :
272 0 : file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
273 : O_RDWR, &aio_ring_fops);
274 0 : if (IS_ERR(file))
275 0 : iput(inode);
276 : return file;
277 : }
278 :
279 1 : static int aio_init_fs_context(struct fs_context *fc)
280 : {
281 1 : if (!init_pseudo(fc, AIO_RING_MAGIC))
282 : return -ENOMEM;
283 1 : fc->s_iflags |= SB_I_NOEXEC;
284 1 : return 0;
285 : }
286 :
287 : /* aio_setup
288 : * Creates the slab caches used by the aio routines, panic on
289 : * failure as this is done early during the boot sequence.
290 : */
291 1 : static int __init aio_setup(void)
292 : {
293 : static struct file_system_type aio_fs = {
294 : .name = "aio",
295 : .init_fs_context = aio_init_fs_context,
296 : .kill_sb = kill_anon_super,
297 : };
298 1 : aio_mnt = kern_mount(&aio_fs);
299 2 : if (IS_ERR(aio_mnt))
300 0 : panic("Failed to create aio fs mount.");
301 :
302 1 : kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
303 1 : kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
304 1 : aio_sysctl_init();
305 1 : return 0;
306 : }
307 : __initcall(aio_setup);
308 :
309 0 : static void put_aio_ring_file(struct kioctx *ctx)
310 : {
311 0 : struct file *aio_ring_file = ctx->aio_ring_file;
312 : struct address_space *i_mapping;
313 :
314 0 : if (aio_ring_file) {
315 0 : truncate_setsize(file_inode(aio_ring_file), 0);
316 :
317 : /* Prevent further access to the kioctx from migratepages */
318 0 : i_mapping = aio_ring_file->f_mapping;
319 0 : spin_lock(&i_mapping->private_lock);
320 0 : i_mapping->private_data = NULL;
321 0 : ctx->aio_ring_file = NULL;
322 0 : spin_unlock(&i_mapping->private_lock);
323 :
324 0 : fput(aio_ring_file);
325 : }
326 0 : }
327 :
328 0 : static void aio_free_ring(struct kioctx *ctx)
329 : {
330 : int i;
331 :
332 : /* Disconnect the kiotx from the ring file. This prevents future
333 : * accesses to the kioctx from page migration.
334 : */
335 0 : put_aio_ring_file(ctx);
336 :
337 0 : for (i = 0; i < ctx->nr_pages; i++) {
338 : struct page *page;
339 : pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
340 : page_count(ctx->ring_pages[i]));
341 0 : page = ctx->ring_pages[i];
342 0 : if (!page)
343 0 : continue;
344 0 : ctx->ring_pages[i] = NULL;
345 0 : put_page(page);
346 : }
347 :
348 0 : if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
349 0 : kfree(ctx->ring_pages);
350 0 : ctx->ring_pages = NULL;
351 : }
352 0 : }
353 :
354 0 : static int aio_ring_mremap(struct vm_area_struct *vma)
355 : {
356 0 : struct file *file = vma->vm_file;
357 0 : struct mm_struct *mm = vma->vm_mm;
358 : struct kioctx_table *table;
359 0 : int i, res = -EINVAL;
360 :
361 0 : spin_lock(&mm->ioctx_lock);
362 : rcu_read_lock();
363 0 : table = rcu_dereference(mm->ioctx_table);
364 0 : for (i = 0; i < table->nr; i++) {
365 : struct kioctx *ctx;
366 :
367 0 : ctx = rcu_dereference(table->table[i]);
368 0 : if (ctx && ctx->aio_ring_file == file) {
369 0 : if (!atomic_read(&ctx->dead)) {
370 0 : ctx->user_id = ctx->mmap_base = vma->vm_start;
371 0 : res = 0;
372 : }
373 : break;
374 : }
375 : }
376 :
377 : rcu_read_unlock();
378 0 : spin_unlock(&mm->ioctx_lock);
379 0 : return res;
380 : }
381 :
382 : static const struct vm_operations_struct aio_ring_vm_ops = {
383 : .mremap = aio_ring_mremap,
384 : #if IS_ENABLED(CONFIG_MMU)
385 : .fault = filemap_fault,
386 : .map_pages = filemap_map_pages,
387 : .page_mkwrite = filemap_page_mkwrite,
388 : #endif
389 : };
390 :
391 0 : static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
392 : {
393 0 : vma->vm_flags |= VM_DONTEXPAND;
394 0 : vma->vm_ops = &aio_ring_vm_ops;
395 0 : return 0;
396 : }
397 :
398 : static const struct file_operations aio_ring_fops = {
399 : .mmap = aio_ring_mmap,
400 : };
401 :
402 : #if IS_ENABLED(CONFIG_MIGRATION)
403 0 : static int aio_migratepage(struct address_space *mapping, struct page *new,
404 : struct page *old, enum migrate_mode mode)
405 : {
406 : struct kioctx *ctx;
407 : unsigned long flags;
408 : pgoff_t idx;
409 : int rc;
410 :
411 : /*
412 : * We cannot support the _NO_COPY case here, because copy needs to
413 : * happen under the ctx->completion_lock. That does not work with the
414 : * migration workflow of MIGRATE_SYNC_NO_COPY.
415 : */
416 0 : if (mode == MIGRATE_SYNC_NO_COPY)
417 : return -EINVAL;
418 :
419 0 : rc = 0;
420 :
421 : /* mapping->private_lock here protects against the kioctx teardown. */
422 0 : spin_lock(&mapping->private_lock);
423 0 : ctx = mapping->private_data;
424 0 : if (!ctx) {
425 : rc = -EINVAL;
426 : goto out;
427 : }
428 :
429 : /* The ring_lock mutex. The prevents aio_read_events() from writing
430 : * to the ring's head, and prevents page migration from mucking in
431 : * a partially initialized kiotx.
432 : */
433 0 : if (!mutex_trylock(&ctx->ring_lock)) {
434 : rc = -EAGAIN;
435 : goto out;
436 : }
437 :
438 0 : idx = old->index;
439 0 : if (idx < (pgoff_t)ctx->nr_pages) {
440 : /* Make sure the old page hasn't already been changed */
441 0 : if (ctx->ring_pages[idx] != old)
442 0 : rc = -EAGAIN;
443 : } else
444 : rc = -EINVAL;
445 :
446 0 : if (rc != 0)
447 : goto out_unlock;
448 :
449 : /* Writeback must be complete */
450 0 : BUG_ON(PageWriteback(old));
451 0 : get_page(new);
452 :
453 0 : rc = migrate_page_move_mapping(mapping, new, old, 1);
454 0 : if (rc != MIGRATEPAGE_SUCCESS) {
455 0 : put_page(new);
456 0 : goto out_unlock;
457 : }
458 :
459 : /* Take completion_lock to prevent other writes to the ring buffer
460 : * while the old page is copied to the new. This prevents new
461 : * events from being lost.
462 : */
463 0 : spin_lock_irqsave(&ctx->completion_lock, flags);
464 0 : migrate_page_copy(new, old);
465 0 : BUG_ON(ctx->ring_pages[idx] != old);
466 0 : ctx->ring_pages[idx] = new;
467 0 : spin_unlock_irqrestore(&ctx->completion_lock, flags);
468 :
469 : /* The old page is no longer accessible. */
470 0 : put_page(old);
471 :
472 : out_unlock:
473 0 : mutex_unlock(&ctx->ring_lock);
474 : out:
475 0 : spin_unlock(&mapping->private_lock);
476 0 : return rc;
477 : }
478 : #endif
479 :
480 : static const struct address_space_operations aio_ctx_aops = {
481 : .dirty_folio = noop_dirty_folio,
482 : #if IS_ENABLED(CONFIG_MIGRATION)
483 : .migratepage = aio_migratepage,
484 : #endif
485 : };
486 :
487 0 : static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
488 : {
489 : struct aio_ring *ring;
490 0 : struct mm_struct *mm = current->mm;
491 : unsigned long size, unused;
492 : int nr_pages;
493 : int i;
494 : struct file *file;
495 :
496 : /* Compensate for the ring buffer's head/tail overlap entry */
497 0 : nr_events += 2; /* 1 is required, 2 for good luck */
498 :
499 0 : size = sizeof(struct aio_ring);
500 0 : size += sizeof(struct io_event) * nr_events;
501 :
502 0 : nr_pages = PFN_UP(size);
503 0 : if (nr_pages < 0)
504 : return -EINVAL;
505 :
506 0 : file = aio_private_file(ctx, nr_pages);
507 0 : if (IS_ERR(file)) {
508 0 : ctx->aio_ring_file = NULL;
509 0 : return -ENOMEM;
510 : }
511 :
512 0 : ctx->aio_ring_file = file;
513 0 : nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
514 0 : / sizeof(struct io_event);
515 :
516 0 : ctx->ring_pages = ctx->internal_pages;
517 0 : if (nr_pages > AIO_RING_PAGES) {
518 0 : ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
519 : GFP_KERNEL);
520 0 : if (!ctx->ring_pages) {
521 0 : put_aio_ring_file(ctx);
522 0 : return -ENOMEM;
523 : }
524 : }
525 :
526 0 : for (i = 0; i < nr_pages; i++) {
527 : struct page *page;
528 0 : page = find_or_create_page(file->f_mapping,
529 : i, GFP_HIGHUSER | __GFP_ZERO);
530 0 : if (!page)
531 : break;
532 0 : pr_debug("pid(%d) page[%d]->count=%d\n",
533 : current->pid, i, page_count(page));
534 0 : SetPageUptodate(page);
535 0 : unlock_page(page);
536 :
537 0 : ctx->ring_pages[i] = page;
538 : }
539 0 : ctx->nr_pages = i;
540 :
541 0 : if (unlikely(i != nr_pages)) {
542 0 : aio_free_ring(ctx);
543 0 : return -ENOMEM;
544 : }
545 :
546 0 : ctx->mmap_size = nr_pages * PAGE_SIZE;
547 0 : pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
548 :
549 0 : if (mmap_write_lock_killable(mm)) {
550 0 : ctx->mmap_size = 0;
551 0 : aio_free_ring(ctx);
552 0 : return -EINTR;
553 : }
554 :
555 0 : ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
556 : PROT_READ | PROT_WRITE,
557 : MAP_SHARED, 0, &unused, NULL);
558 0 : mmap_write_unlock(mm);
559 0 : if (IS_ERR((void *)ctx->mmap_base)) {
560 0 : ctx->mmap_size = 0;
561 0 : aio_free_ring(ctx);
562 0 : return -ENOMEM;
563 : }
564 :
565 : pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
566 :
567 0 : ctx->user_id = ctx->mmap_base;
568 0 : ctx->nr_events = nr_events; /* trusted copy */
569 :
570 0 : ring = kmap_atomic(ctx->ring_pages[0]);
571 0 : ring->nr = nr_events; /* user copy */
572 0 : ring->id = ~0U;
573 0 : ring->head = ring->tail = 0;
574 0 : ring->magic = AIO_RING_MAGIC;
575 0 : ring->compat_features = AIO_RING_COMPAT_FEATURES;
576 0 : ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
577 0 : ring->header_length = sizeof(struct aio_ring);
578 0 : kunmap_atomic(ring);
579 0 : flush_dcache_page(ctx->ring_pages[0]);
580 :
581 0 : return 0;
582 : }
583 :
584 : #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
585 : #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
586 : #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
587 :
588 0 : void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
589 : {
590 0 : struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
591 0 : struct kioctx *ctx = req->ki_ctx;
592 : unsigned long flags;
593 :
594 0 : if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
595 : return;
596 :
597 0 : spin_lock_irqsave(&ctx->ctx_lock, flags);
598 0 : list_add_tail(&req->ki_list, &ctx->active_reqs);
599 0 : req->ki_cancel = cancel;
600 0 : spin_unlock_irqrestore(&ctx->ctx_lock, flags);
601 : }
602 : EXPORT_SYMBOL(kiocb_set_cancel_fn);
603 :
604 : /*
605 : * free_ioctx() should be RCU delayed to synchronize against the RCU
606 : * protected lookup_ioctx() and also needs process context to call
607 : * aio_free_ring(). Use rcu_work.
608 : */
609 0 : static void free_ioctx(struct work_struct *work)
610 : {
611 0 : struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
612 : free_rwork);
613 : pr_debug("freeing %p\n", ctx);
614 :
615 0 : aio_free_ring(ctx);
616 0 : free_percpu(ctx->cpu);
617 0 : percpu_ref_exit(&ctx->reqs);
618 0 : percpu_ref_exit(&ctx->users);
619 0 : kmem_cache_free(kioctx_cachep, ctx);
620 0 : }
621 :
622 0 : static void free_ioctx_reqs(struct percpu_ref *ref)
623 : {
624 0 : struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
625 :
626 : /* At this point we know that there are no any in-flight requests */
627 0 : if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
628 0 : complete(&ctx->rq_wait->comp);
629 :
630 : /* Synchronize against RCU protected table->table[] dereferences */
631 0 : INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
632 0 : queue_rcu_work(system_wq, &ctx->free_rwork);
633 0 : }
634 :
635 : /*
636 : * When this function runs, the kioctx has been removed from the "hash table"
637 : * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
638 : * now it's safe to cancel any that need to be.
639 : */
640 0 : static void free_ioctx_users(struct percpu_ref *ref)
641 : {
642 0 : struct kioctx *ctx = container_of(ref, struct kioctx, users);
643 : struct aio_kiocb *req;
644 :
645 0 : spin_lock_irq(&ctx->ctx_lock);
646 :
647 0 : while (!list_empty(&ctx->active_reqs)) {
648 0 : req = list_first_entry(&ctx->active_reqs,
649 : struct aio_kiocb, ki_list);
650 0 : req->ki_cancel(&req->rw);
651 0 : list_del_init(&req->ki_list);
652 : }
653 :
654 0 : spin_unlock_irq(&ctx->ctx_lock);
655 :
656 0 : percpu_ref_kill(&ctx->reqs);
657 0 : percpu_ref_put(&ctx->reqs);
658 0 : }
659 :
660 0 : static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
661 : {
662 : unsigned i, new_nr;
663 : struct kioctx_table *table, *old;
664 : struct aio_ring *ring;
665 :
666 0 : spin_lock(&mm->ioctx_lock);
667 0 : table = rcu_dereference_raw(mm->ioctx_table);
668 :
669 : while (1) {
670 0 : if (table)
671 0 : for (i = 0; i < table->nr; i++)
672 0 : if (!rcu_access_pointer(table->table[i])) {
673 0 : ctx->id = i;
674 0 : rcu_assign_pointer(table->table[i], ctx);
675 0 : spin_unlock(&mm->ioctx_lock);
676 :
677 : /* While kioctx setup is in progress,
678 : * we are protected from page migration
679 : * changes ring_pages by ->ring_lock.
680 : */
681 0 : ring = kmap_atomic(ctx->ring_pages[0]);
682 0 : ring->id = ctx->id;
683 0 : kunmap_atomic(ring);
684 0 : return 0;
685 : }
686 :
687 0 : new_nr = (table ? table->nr : 1) * 4;
688 0 : spin_unlock(&mm->ioctx_lock);
689 :
690 0 : table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
691 0 : if (!table)
692 : return -ENOMEM;
693 :
694 0 : table->nr = new_nr;
695 :
696 0 : spin_lock(&mm->ioctx_lock);
697 0 : old = rcu_dereference_raw(mm->ioctx_table);
698 :
699 0 : if (!old) {
700 0 : rcu_assign_pointer(mm->ioctx_table, table);
701 0 : } else if (table->nr > old->nr) {
702 0 : memcpy(table->table, old->table,
703 0 : old->nr * sizeof(struct kioctx *));
704 :
705 0 : rcu_assign_pointer(mm->ioctx_table, table);
706 0 : kfree_rcu(old, rcu);
707 : } else {
708 0 : kfree(table);
709 0 : table = old;
710 : }
711 : }
712 : }
713 :
714 0 : static void aio_nr_sub(unsigned nr)
715 : {
716 0 : spin_lock(&aio_nr_lock);
717 0 : if (WARN_ON(aio_nr - nr > aio_nr))
718 0 : aio_nr = 0;
719 : else
720 0 : aio_nr -= nr;
721 0 : spin_unlock(&aio_nr_lock);
722 0 : }
723 :
724 : /* ioctx_alloc
725 : * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
726 : */
727 0 : static struct kioctx *ioctx_alloc(unsigned nr_events)
728 : {
729 0 : struct mm_struct *mm = current->mm;
730 : struct kioctx *ctx;
731 0 : int err = -ENOMEM;
732 :
733 : /*
734 : * Store the original nr_events -- what userspace passed to io_setup(),
735 : * for counting against the global limit -- before it changes.
736 : */
737 0 : unsigned int max_reqs = nr_events;
738 :
739 : /*
740 : * We keep track of the number of available ringbuffer slots, to prevent
741 : * overflow (reqs_available), and we also use percpu counters for this.
742 : *
743 : * So since up to half the slots might be on other cpu's percpu counters
744 : * and unavailable, double nr_events so userspace sees what they
745 : * expected: additionally, we move req_batch slots to/from percpu
746 : * counters at a time, so make sure that isn't 0:
747 : */
748 0 : nr_events = max(nr_events, num_possible_cpus() * 4);
749 0 : nr_events *= 2;
750 :
751 : /* Prevent overflows */
752 0 : if (nr_events > (0x10000000U / sizeof(struct io_event))) {
753 : pr_debug("ENOMEM: nr_events too high\n");
754 : return ERR_PTR(-EINVAL);
755 : }
756 :
757 0 : if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
758 : return ERR_PTR(-EAGAIN);
759 :
760 0 : ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
761 0 : if (!ctx)
762 : return ERR_PTR(-ENOMEM);
763 :
764 0 : ctx->max_reqs = max_reqs;
765 :
766 0 : spin_lock_init(&ctx->ctx_lock);
767 0 : spin_lock_init(&ctx->completion_lock);
768 0 : mutex_init(&ctx->ring_lock);
769 : /* Protect against page migration throughout kiotx setup by keeping
770 : * the ring_lock mutex held until setup is complete. */
771 0 : mutex_lock(&ctx->ring_lock);
772 0 : init_waitqueue_head(&ctx->wait);
773 :
774 0 : INIT_LIST_HEAD(&ctx->active_reqs);
775 :
776 0 : if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
777 : goto err;
778 :
779 0 : if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
780 : goto err;
781 :
782 0 : ctx->cpu = alloc_percpu(struct kioctx_cpu);
783 0 : if (!ctx->cpu)
784 : goto err;
785 :
786 0 : err = aio_setup_ring(ctx, nr_events);
787 0 : if (err < 0)
788 : goto err;
789 :
790 0 : atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
791 0 : ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
792 0 : if (ctx->req_batch < 1)
793 0 : ctx->req_batch = 1;
794 :
795 : /* limit the number of system wide aios */
796 0 : spin_lock(&aio_nr_lock);
797 0 : if (aio_nr + ctx->max_reqs > aio_max_nr ||
798 : aio_nr + ctx->max_reqs < aio_nr) {
799 0 : spin_unlock(&aio_nr_lock);
800 0 : err = -EAGAIN;
801 0 : goto err_ctx;
802 : }
803 0 : aio_nr += ctx->max_reqs;
804 0 : spin_unlock(&aio_nr_lock);
805 :
806 0 : percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
807 0 : percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
808 :
809 0 : err = ioctx_add_table(ctx, mm);
810 0 : if (err)
811 : goto err_cleanup;
812 :
813 : /* Release the ring_lock mutex now that all setup is complete. */
814 0 : mutex_unlock(&ctx->ring_lock);
815 :
816 : pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
817 : ctx, ctx->user_id, mm, ctx->nr_events);
818 0 : return ctx;
819 :
820 : err_cleanup:
821 0 : aio_nr_sub(ctx->max_reqs);
822 : err_ctx:
823 0 : atomic_set(&ctx->dead, 1);
824 0 : if (ctx->mmap_size)
825 0 : vm_munmap(ctx->mmap_base, ctx->mmap_size);
826 0 : aio_free_ring(ctx);
827 : err:
828 0 : mutex_unlock(&ctx->ring_lock);
829 0 : free_percpu(ctx->cpu);
830 0 : percpu_ref_exit(&ctx->reqs);
831 0 : percpu_ref_exit(&ctx->users);
832 0 : kmem_cache_free(kioctx_cachep, ctx);
833 : pr_debug("error allocating ioctx %d\n", err);
834 0 : return ERR_PTR(err);
835 : }
836 :
837 : /* kill_ioctx
838 : * Cancels all outstanding aio requests on an aio context. Used
839 : * when the processes owning a context have all exited to encourage
840 : * the rapid destruction of the kioctx.
841 : */
842 0 : static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
843 : struct ctx_rq_wait *wait)
844 : {
845 : struct kioctx_table *table;
846 :
847 0 : spin_lock(&mm->ioctx_lock);
848 0 : if (atomic_xchg(&ctx->dead, 1)) {
849 0 : spin_unlock(&mm->ioctx_lock);
850 0 : return -EINVAL;
851 : }
852 :
853 0 : table = rcu_dereference_raw(mm->ioctx_table);
854 0 : WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
855 0 : RCU_INIT_POINTER(table->table[ctx->id], NULL);
856 0 : spin_unlock(&mm->ioctx_lock);
857 :
858 : /* free_ioctx_reqs() will do the necessary RCU synchronization */
859 0 : wake_up_all(&ctx->wait);
860 :
861 : /*
862 : * It'd be more correct to do this in free_ioctx(), after all
863 : * the outstanding kiocbs have finished - but by then io_destroy
864 : * has already returned, so io_setup() could potentially return
865 : * -EAGAIN with no ioctxs actually in use (as far as userspace
866 : * could tell).
867 : */
868 0 : aio_nr_sub(ctx->max_reqs);
869 :
870 0 : if (ctx->mmap_size)
871 0 : vm_munmap(ctx->mmap_base, ctx->mmap_size);
872 :
873 0 : ctx->rq_wait = wait;
874 0 : percpu_ref_kill(&ctx->users);
875 0 : return 0;
876 : }
877 :
878 : /*
879 : * exit_aio: called when the last user of mm goes away. At this point, there is
880 : * no way for any new requests to be submited or any of the io_* syscalls to be
881 : * called on the context.
882 : *
883 : * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
884 : * them.
885 : */
886 0 : void exit_aio(struct mm_struct *mm)
887 : {
888 0 : struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
889 : struct ctx_rq_wait wait;
890 : int i, skipped;
891 :
892 0 : if (!table)
893 0 : return;
894 :
895 0 : atomic_set(&wait.count, table->nr);
896 0 : init_completion(&wait.comp);
897 :
898 0 : skipped = 0;
899 0 : for (i = 0; i < table->nr; ++i) {
900 0 : struct kioctx *ctx =
901 0 : rcu_dereference_protected(table->table[i], true);
902 :
903 0 : if (!ctx) {
904 0 : skipped++;
905 0 : continue;
906 : }
907 :
908 : /*
909 : * We don't need to bother with munmap() here - exit_mmap(mm)
910 : * is coming and it'll unmap everything. And we simply can't,
911 : * this is not necessarily our ->mm.
912 : * Since kill_ioctx() uses non-zero ->mmap_size as indicator
913 : * that it needs to unmap the area, just set it to 0.
914 : */
915 0 : ctx->mmap_size = 0;
916 0 : kill_ioctx(mm, ctx, &wait);
917 : }
918 :
919 0 : if (!atomic_sub_and_test(skipped, &wait.count)) {
920 : /* Wait until all IO for the context are done. */
921 0 : wait_for_completion(&wait.comp);
922 : }
923 :
924 0 : RCU_INIT_POINTER(mm->ioctx_table, NULL);
925 0 : kfree(table);
926 : }
927 :
928 0 : static void put_reqs_available(struct kioctx *ctx, unsigned nr)
929 : {
930 : struct kioctx_cpu *kcpu;
931 : unsigned long flags;
932 :
933 0 : local_irq_save(flags);
934 0 : kcpu = this_cpu_ptr(ctx->cpu);
935 0 : kcpu->reqs_available += nr;
936 :
937 0 : while (kcpu->reqs_available >= ctx->req_batch * 2) {
938 0 : kcpu->reqs_available -= ctx->req_batch;
939 0 : atomic_add(ctx->req_batch, &ctx->reqs_available);
940 : }
941 :
942 0 : local_irq_restore(flags);
943 0 : }
944 :
945 0 : static bool __get_reqs_available(struct kioctx *ctx)
946 : {
947 : struct kioctx_cpu *kcpu;
948 0 : bool ret = false;
949 : unsigned long flags;
950 :
951 0 : local_irq_save(flags);
952 0 : kcpu = this_cpu_ptr(ctx->cpu);
953 0 : if (!kcpu->reqs_available) {
954 0 : int old, avail = atomic_read(&ctx->reqs_available);
955 :
956 : do {
957 0 : if (avail < ctx->req_batch)
958 : goto out;
959 :
960 0 : old = avail;
961 0 : avail = atomic_cmpxchg(&ctx->reqs_available,
962 0 : avail, avail - ctx->req_batch);
963 0 : } while (avail != old);
964 :
965 0 : kcpu->reqs_available += ctx->req_batch;
966 : }
967 :
968 0 : ret = true;
969 0 : kcpu->reqs_available--;
970 : out:
971 0 : local_irq_restore(flags);
972 0 : return ret;
973 : }
974 :
975 : /* refill_reqs_available
976 : * Updates the reqs_available reference counts used for tracking the
977 : * number of free slots in the completion ring. This can be called
978 : * from aio_complete() (to optimistically update reqs_available) or
979 : * from aio_get_req() (the we're out of events case). It must be
980 : * called holding ctx->completion_lock.
981 : */
982 0 : static void refill_reqs_available(struct kioctx *ctx, unsigned head,
983 : unsigned tail)
984 : {
985 : unsigned events_in_ring, completed;
986 :
987 : /* Clamp head since userland can write to it. */
988 0 : head %= ctx->nr_events;
989 0 : if (head <= tail)
990 0 : events_in_ring = tail - head;
991 : else
992 0 : events_in_ring = ctx->nr_events - (head - tail);
993 :
994 0 : completed = ctx->completed_events;
995 0 : if (events_in_ring < completed)
996 0 : completed -= events_in_ring;
997 : else
998 : completed = 0;
999 :
1000 0 : if (!completed)
1001 : return;
1002 :
1003 0 : ctx->completed_events -= completed;
1004 0 : put_reqs_available(ctx, completed);
1005 : }
1006 :
1007 : /* user_refill_reqs_available
1008 : * Called to refill reqs_available when aio_get_req() encounters an
1009 : * out of space in the completion ring.
1010 : */
1011 0 : static void user_refill_reqs_available(struct kioctx *ctx)
1012 : {
1013 0 : spin_lock_irq(&ctx->completion_lock);
1014 0 : if (ctx->completed_events) {
1015 : struct aio_ring *ring;
1016 : unsigned head;
1017 :
1018 : /* Access of ring->head may race with aio_read_events_ring()
1019 : * here, but that's okay since whether we read the old version
1020 : * or the new version, and either will be valid. The important
1021 : * part is that head cannot pass tail since we prevent
1022 : * aio_complete() from updating tail by holding
1023 : * ctx->completion_lock. Even if head is invalid, the check
1024 : * against ctx->completed_events below will make sure we do the
1025 : * safe/right thing.
1026 : */
1027 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1028 0 : head = ring->head;
1029 0 : kunmap_atomic(ring);
1030 :
1031 0 : refill_reqs_available(ctx, head, ctx->tail);
1032 : }
1033 :
1034 0 : spin_unlock_irq(&ctx->completion_lock);
1035 0 : }
1036 :
1037 0 : static bool get_reqs_available(struct kioctx *ctx)
1038 : {
1039 0 : if (__get_reqs_available(ctx))
1040 : return true;
1041 0 : user_refill_reqs_available(ctx);
1042 0 : return __get_reqs_available(ctx);
1043 : }
1044 :
1045 : /* aio_get_req
1046 : * Allocate a slot for an aio request.
1047 : * Returns NULL if no requests are free.
1048 : *
1049 : * The refcount is initialized to 2 - one for the async op completion,
1050 : * one for the synchronous code that does this.
1051 : */
1052 0 : static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1053 : {
1054 : struct aio_kiocb *req;
1055 :
1056 0 : req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1057 0 : if (unlikely(!req))
1058 : return NULL;
1059 :
1060 0 : if (unlikely(!get_reqs_available(ctx))) {
1061 0 : kmem_cache_free(kiocb_cachep, req);
1062 0 : return NULL;
1063 : }
1064 :
1065 0 : percpu_ref_get(&ctx->reqs);
1066 0 : req->ki_ctx = ctx;
1067 0 : INIT_LIST_HEAD(&req->ki_list);
1068 0 : refcount_set(&req->ki_refcnt, 2);
1069 0 : req->ki_eventfd = NULL;
1070 0 : return req;
1071 : }
1072 :
1073 0 : static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1074 : {
1075 0 : struct aio_ring __user *ring = (void __user *)ctx_id;
1076 0 : struct mm_struct *mm = current->mm;
1077 0 : struct kioctx *ctx, *ret = NULL;
1078 : struct kioctx_table *table;
1079 : unsigned id;
1080 :
1081 0 : if (get_user(id, &ring->id))
1082 : return NULL;
1083 :
1084 : rcu_read_lock();
1085 0 : table = rcu_dereference(mm->ioctx_table);
1086 :
1087 0 : if (!table || id >= table->nr)
1088 : goto out;
1089 :
1090 0 : id = array_index_nospec(id, table->nr);
1091 0 : ctx = rcu_dereference(table->table[id]);
1092 0 : if (ctx && ctx->user_id == ctx_id) {
1093 0 : if (percpu_ref_tryget_live(&ctx->users))
1094 0 : ret = ctx;
1095 : }
1096 : out:
1097 : rcu_read_unlock();
1098 0 : return ret;
1099 : }
1100 :
1101 0 : static inline void iocb_destroy(struct aio_kiocb *iocb)
1102 : {
1103 0 : if (iocb->ki_eventfd)
1104 0 : eventfd_ctx_put(iocb->ki_eventfd);
1105 0 : if (iocb->ki_filp)
1106 0 : fput(iocb->ki_filp);
1107 0 : percpu_ref_put(&iocb->ki_ctx->reqs);
1108 0 : kmem_cache_free(kiocb_cachep, iocb);
1109 0 : }
1110 :
1111 : /* aio_complete
1112 : * Called when the io request on the given iocb is complete.
1113 : */
1114 0 : static void aio_complete(struct aio_kiocb *iocb)
1115 : {
1116 0 : struct kioctx *ctx = iocb->ki_ctx;
1117 : struct aio_ring *ring;
1118 : struct io_event *ev_page, *event;
1119 : unsigned tail, pos, head;
1120 : unsigned long flags;
1121 :
1122 : /*
1123 : * Add a completion event to the ring buffer. Must be done holding
1124 : * ctx->completion_lock to prevent other code from messing with the tail
1125 : * pointer since we might be called from irq context.
1126 : */
1127 0 : spin_lock_irqsave(&ctx->completion_lock, flags);
1128 :
1129 0 : tail = ctx->tail;
1130 0 : pos = tail + AIO_EVENTS_OFFSET;
1131 :
1132 0 : if (++tail >= ctx->nr_events)
1133 0 : tail = 0;
1134 :
1135 0 : ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1136 0 : event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1137 :
1138 0 : *event = iocb->ki_res;
1139 :
1140 0 : kunmap_atomic(ev_page);
1141 0 : flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1142 :
1143 : pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1144 : (void __user *)(unsigned long)iocb->ki_res.obj,
1145 : iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1146 :
1147 : /* after flagging the request as done, we
1148 : * must never even look at it again
1149 : */
1150 0 : smp_wmb(); /* make event visible before updating tail */
1151 :
1152 0 : ctx->tail = tail;
1153 :
1154 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1155 0 : head = ring->head;
1156 0 : ring->tail = tail;
1157 0 : kunmap_atomic(ring);
1158 0 : flush_dcache_page(ctx->ring_pages[0]);
1159 :
1160 0 : ctx->completed_events++;
1161 0 : if (ctx->completed_events > 1)
1162 0 : refill_reqs_available(ctx, head, tail);
1163 0 : spin_unlock_irqrestore(&ctx->completion_lock, flags);
1164 :
1165 : pr_debug("added to ring %p at [%u]\n", iocb, tail);
1166 :
1167 : /*
1168 : * Check if the user asked us to deliver the result through an
1169 : * eventfd. The eventfd_signal() function is safe to be called
1170 : * from IRQ context.
1171 : */
1172 0 : if (iocb->ki_eventfd)
1173 0 : eventfd_signal(iocb->ki_eventfd, 1);
1174 :
1175 : /*
1176 : * We have to order our ring_info tail store above and test
1177 : * of the wait list below outside the wait lock. This is
1178 : * like in wake_up_bit() where clearing a bit has to be
1179 : * ordered with the unlocked test.
1180 : */
1181 0 : smp_mb();
1182 :
1183 0 : if (waitqueue_active(&ctx->wait))
1184 0 : wake_up(&ctx->wait);
1185 0 : }
1186 :
1187 0 : static inline void iocb_put(struct aio_kiocb *iocb)
1188 : {
1189 0 : if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1190 0 : aio_complete(iocb);
1191 0 : iocb_destroy(iocb);
1192 : }
1193 0 : }
1194 :
1195 : /* aio_read_events_ring
1196 : * Pull an event off of the ioctx's event ring. Returns the number of
1197 : * events fetched
1198 : */
1199 0 : static long aio_read_events_ring(struct kioctx *ctx,
1200 : struct io_event __user *event, long nr)
1201 : {
1202 : struct aio_ring *ring;
1203 : unsigned head, tail, pos;
1204 0 : long ret = 0;
1205 : int copy_ret;
1206 :
1207 : /*
1208 : * The mutex can block and wake us up and that will cause
1209 : * wait_event_interruptible_hrtimeout() to schedule without sleeping
1210 : * and repeat. This should be rare enough that it doesn't cause
1211 : * peformance issues. See the comment in read_events() for more detail.
1212 : */
1213 : sched_annotate_sleep();
1214 0 : mutex_lock(&ctx->ring_lock);
1215 :
1216 : /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1217 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1218 0 : head = ring->head;
1219 0 : tail = ring->tail;
1220 0 : kunmap_atomic(ring);
1221 :
1222 : /*
1223 : * Ensure that once we've read the current tail pointer, that
1224 : * we also see the events that were stored up to the tail.
1225 : */
1226 0 : smp_rmb();
1227 :
1228 : pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1229 :
1230 0 : if (head == tail)
1231 : goto out;
1232 :
1233 0 : head %= ctx->nr_events;
1234 0 : tail %= ctx->nr_events;
1235 :
1236 0 : while (ret < nr) {
1237 : long avail;
1238 : struct io_event *ev;
1239 : struct page *page;
1240 :
1241 0 : avail = (head <= tail ? tail : ctx->nr_events) - head;
1242 0 : if (head == tail)
1243 : break;
1244 :
1245 0 : pos = head + AIO_EVENTS_OFFSET;
1246 0 : page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1247 0 : pos %= AIO_EVENTS_PER_PAGE;
1248 :
1249 0 : avail = min(avail, nr - ret);
1250 0 : avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1251 :
1252 0 : ev = kmap(page);
1253 0 : copy_ret = copy_to_user(event + ret, ev + pos,
1254 : sizeof(*ev) * avail);
1255 0 : kunmap(page);
1256 :
1257 0 : if (unlikely(copy_ret)) {
1258 : ret = -EFAULT;
1259 : goto out;
1260 : }
1261 :
1262 0 : ret += avail;
1263 0 : head += avail;
1264 0 : head %= ctx->nr_events;
1265 : }
1266 :
1267 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1268 0 : ring->head = head;
1269 0 : kunmap_atomic(ring);
1270 0 : flush_dcache_page(ctx->ring_pages[0]);
1271 :
1272 : pr_debug("%li h%u t%u\n", ret, head, tail);
1273 : out:
1274 0 : mutex_unlock(&ctx->ring_lock);
1275 :
1276 0 : return ret;
1277 : }
1278 :
1279 0 : static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1280 : struct io_event __user *event, long *i)
1281 : {
1282 0 : long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1283 :
1284 0 : if (ret > 0)
1285 0 : *i += ret;
1286 :
1287 0 : if (unlikely(atomic_read(&ctx->dead)))
1288 0 : ret = -EINVAL;
1289 :
1290 0 : if (!*i)
1291 0 : *i = ret;
1292 :
1293 0 : return ret < 0 || *i >= min_nr;
1294 : }
1295 :
1296 0 : static long read_events(struct kioctx *ctx, long min_nr, long nr,
1297 : struct io_event __user *event,
1298 : ktime_t until)
1299 : {
1300 0 : long ret = 0;
1301 :
1302 : /*
1303 : * Note that aio_read_events() is being called as the conditional - i.e.
1304 : * we're calling it after prepare_to_wait() has set task state to
1305 : * TASK_INTERRUPTIBLE.
1306 : *
1307 : * But aio_read_events() can block, and if it blocks it's going to flip
1308 : * the task state back to TASK_RUNNING.
1309 : *
1310 : * This should be ok, provided it doesn't flip the state back to
1311 : * TASK_RUNNING and return 0 too much - that causes us to spin. That
1312 : * will only happen if the mutex_lock() call blocks, and we then find
1313 : * the ringbuffer empty. So in practice we should be ok, but it's
1314 : * something to be aware of when touching this code.
1315 : */
1316 0 : if (until == 0)
1317 0 : aio_read_events(ctx, min_nr, nr, event, &ret);
1318 : else
1319 0 : wait_event_interruptible_hrtimeout(ctx->wait,
1320 : aio_read_events(ctx, min_nr, nr, event, &ret),
1321 : until);
1322 0 : return ret;
1323 : }
1324 :
1325 : /* sys_io_setup:
1326 : * Create an aio_context capable of receiving at least nr_events.
1327 : * ctxp must not point to an aio_context that already exists, and
1328 : * must be initialized to 0 prior to the call. On successful
1329 : * creation of the aio_context, *ctxp is filled in with the resulting
1330 : * handle. May fail with -EINVAL if *ctxp is not initialized,
1331 : * if the specified nr_events exceeds internal limits. May fail
1332 : * with -EAGAIN if the specified nr_events exceeds the user's limit
1333 : * of available events. May fail with -ENOMEM if insufficient kernel
1334 : * resources are available. May fail with -EFAULT if an invalid
1335 : * pointer is passed for ctxp. Will fail with -ENOSYS if not
1336 : * implemented.
1337 : */
1338 0 : SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1339 : {
1340 0 : struct kioctx *ioctx = NULL;
1341 : unsigned long ctx;
1342 : long ret;
1343 :
1344 0 : ret = get_user(ctx, ctxp);
1345 0 : if (unlikely(ret))
1346 : goto out;
1347 :
1348 0 : ret = -EINVAL;
1349 0 : if (unlikely(ctx || nr_events == 0)) {
1350 : pr_debug("EINVAL: ctx %lu nr_events %u\n",
1351 : ctx, nr_events);
1352 : goto out;
1353 : }
1354 :
1355 0 : ioctx = ioctx_alloc(nr_events);
1356 0 : ret = PTR_ERR(ioctx);
1357 0 : if (!IS_ERR(ioctx)) {
1358 0 : ret = put_user(ioctx->user_id, ctxp);
1359 0 : if (ret)
1360 0 : kill_ioctx(current->mm, ioctx, NULL);
1361 0 : percpu_ref_put(&ioctx->users);
1362 : }
1363 :
1364 : out:
1365 0 : return ret;
1366 : }
1367 :
1368 : #ifdef CONFIG_COMPAT
1369 : COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1370 : {
1371 : struct kioctx *ioctx = NULL;
1372 : unsigned long ctx;
1373 : long ret;
1374 :
1375 : ret = get_user(ctx, ctx32p);
1376 : if (unlikely(ret))
1377 : goto out;
1378 :
1379 : ret = -EINVAL;
1380 : if (unlikely(ctx || nr_events == 0)) {
1381 : pr_debug("EINVAL: ctx %lu nr_events %u\n",
1382 : ctx, nr_events);
1383 : goto out;
1384 : }
1385 :
1386 : ioctx = ioctx_alloc(nr_events);
1387 : ret = PTR_ERR(ioctx);
1388 : if (!IS_ERR(ioctx)) {
1389 : /* truncating is ok because it's a user address */
1390 : ret = put_user((u32)ioctx->user_id, ctx32p);
1391 : if (ret)
1392 : kill_ioctx(current->mm, ioctx, NULL);
1393 : percpu_ref_put(&ioctx->users);
1394 : }
1395 :
1396 : out:
1397 : return ret;
1398 : }
1399 : #endif
1400 :
1401 : /* sys_io_destroy:
1402 : * Destroy the aio_context specified. May cancel any outstanding
1403 : * AIOs and block on completion. Will fail with -ENOSYS if not
1404 : * implemented. May fail with -EINVAL if the context pointed to
1405 : * is invalid.
1406 : */
1407 0 : SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1408 : {
1409 0 : struct kioctx *ioctx = lookup_ioctx(ctx);
1410 0 : if (likely(NULL != ioctx)) {
1411 : struct ctx_rq_wait wait;
1412 : int ret;
1413 :
1414 0 : init_completion(&wait.comp);
1415 0 : atomic_set(&wait.count, 1);
1416 :
1417 : /* Pass requests_done to kill_ioctx() where it can be set
1418 : * in a thread-safe way. If we try to set it here then we have
1419 : * a race condition if two io_destroy() called simultaneously.
1420 : */
1421 0 : ret = kill_ioctx(current->mm, ioctx, &wait);
1422 0 : percpu_ref_put(&ioctx->users);
1423 :
1424 : /* Wait until all IO for the context are done. Otherwise kernel
1425 : * keep using user-space buffers even if user thinks the context
1426 : * is destroyed.
1427 : */
1428 0 : if (!ret)
1429 0 : wait_for_completion(&wait.comp);
1430 :
1431 0 : return ret;
1432 : }
1433 : pr_debug("EINVAL: invalid context id\n");
1434 : return -EINVAL;
1435 : }
1436 :
1437 0 : static void aio_remove_iocb(struct aio_kiocb *iocb)
1438 : {
1439 0 : struct kioctx *ctx = iocb->ki_ctx;
1440 : unsigned long flags;
1441 :
1442 0 : spin_lock_irqsave(&ctx->ctx_lock, flags);
1443 0 : list_del(&iocb->ki_list);
1444 0 : spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1445 0 : }
1446 :
1447 0 : static void aio_complete_rw(struct kiocb *kiocb, long res)
1448 : {
1449 0 : struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1450 :
1451 0 : if (!list_empty_careful(&iocb->ki_list))
1452 0 : aio_remove_iocb(iocb);
1453 :
1454 0 : if (kiocb->ki_flags & IOCB_WRITE) {
1455 0 : struct inode *inode = file_inode(kiocb->ki_filp);
1456 :
1457 : /*
1458 : * Tell lockdep we inherited freeze protection from submission
1459 : * thread.
1460 : */
1461 0 : if (S_ISREG(inode->i_mode))
1462 : __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
1463 0 : file_end_write(kiocb->ki_filp);
1464 : }
1465 :
1466 0 : iocb->ki_res.res = res;
1467 0 : iocb->ki_res.res2 = 0;
1468 0 : iocb_put(iocb);
1469 0 : }
1470 :
1471 0 : static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1472 : {
1473 : int ret;
1474 :
1475 0 : req->ki_complete = aio_complete_rw;
1476 0 : req->private = NULL;
1477 0 : req->ki_pos = iocb->aio_offset;
1478 0 : req->ki_flags = iocb_flags(req->ki_filp);
1479 0 : if (iocb->aio_flags & IOCB_FLAG_RESFD)
1480 0 : req->ki_flags |= IOCB_EVENTFD;
1481 0 : if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1482 : /*
1483 : * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1484 : * aio_reqprio is interpreted as an I/O scheduling
1485 : * class and priority.
1486 : */
1487 0 : ret = ioprio_check_cap(iocb->aio_reqprio);
1488 0 : if (ret) {
1489 : pr_debug("aio ioprio check cap error: %d\n", ret);
1490 : return ret;
1491 : }
1492 :
1493 0 : req->ki_ioprio = iocb->aio_reqprio;
1494 : } else
1495 0 : req->ki_ioprio = get_current_ioprio();
1496 :
1497 0 : ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
1498 0 : if (unlikely(ret))
1499 : return ret;
1500 :
1501 0 : req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1502 0 : return 0;
1503 : }
1504 :
1505 0 : static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1506 : struct iovec **iovec, bool vectored, bool compat,
1507 : struct iov_iter *iter)
1508 : {
1509 0 : void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1510 0 : size_t len = iocb->aio_nbytes;
1511 :
1512 0 : if (!vectored) {
1513 0 : ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
1514 0 : *iovec = NULL;
1515 0 : return ret;
1516 : }
1517 :
1518 0 : return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1519 : }
1520 :
1521 : static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1522 : {
1523 0 : switch (ret) {
1524 : case -EIOCBQUEUED:
1525 : break;
1526 : case -ERESTARTSYS:
1527 : case -ERESTARTNOINTR:
1528 : case -ERESTARTNOHAND:
1529 : case -ERESTART_RESTARTBLOCK:
1530 : /*
1531 : * There's no easy way to restart the syscall since other AIO's
1532 : * may be already running. Just fail this IO with EINTR.
1533 : */
1534 0 : ret = -EINTR;
1535 : fallthrough;
1536 : default:
1537 0 : req->ki_complete(req, ret);
1538 : }
1539 : }
1540 :
1541 0 : static int aio_read(struct kiocb *req, const struct iocb *iocb,
1542 : bool vectored, bool compat)
1543 : {
1544 0 : struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1545 : struct iov_iter iter;
1546 : struct file *file;
1547 : int ret;
1548 :
1549 0 : ret = aio_prep_rw(req, iocb);
1550 0 : if (ret)
1551 : return ret;
1552 0 : file = req->ki_filp;
1553 0 : if (unlikely(!(file->f_mode & FMODE_READ)))
1554 : return -EBADF;
1555 0 : if (unlikely(!file->f_op->read_iter))
1556 : return -EINVAL;
1557 :
1558 0 : ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
1559 0 : if (ret < 0)
1560 : return ret;
1561 0 : ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1562 0 : if (!ret)
1563 0 : aio_rw_done(req, call_read_iter(file, req, &iter));
1564 0 : kfree(iovec);
1565 0 : return ret;
1566 : }
1567 :
1568 0 : static int aio_write(struct kiocb *req, const struct iocb *iocb,
1569 : bool vectored, bool compat)
1570 : {
1571 0 : struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1572 : struct iov_iter iter;
1573 : struct file *file;
1574 : int ret;
1575 :
1576 0 : ret = aio_prep_rw(req, iocb);
1577 0 : if (ret)
1578 : return ret;
1579 0 : file = req->ki_filp;
1580 :
1581 0 : if (unlikely(!(file->f_mode & FMODE_WRITE)))
1582 : return -EBADF;
1583 0 : if (unlikely(!file->f_op->write_iter))
1584 : return -EINVAL;
1585 :
1586 0 : ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
1587 0 : if (ret < 0)
1588 : return ret;
1589 0 : ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1590 0 : if (!ret) {
1591 : /*
1592 : * Open-code file_start_write here to grab freeze protection,
1593 : * which will be released by another thread in
1594 : * aio_complete_rw(). Fool lockdep by telling it the lock got
1595 : * released so that it doesn't complain about the held lock when
1596 : * we return to userspace.
1597 : */
1598 0 : if (S_ISREG(file_inode(file)->i_mode)) {
1599 0 : sb_start_write(file_inode(file)->i_sb);
1600 : __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1601 : }
1602 0 : req->ki_flags |= IOCB_WRITE;
1603 0 : aio_rw_done(req, call_write_iter(file, req, &iter));
1604 : }
1605 0 : kfree(iovec);
1606 0 : return ret;
1607 : }
1608 :
1609 0 : static void aio_fsync_work(struct work_struct *work)
1610 : {
1611 0 : struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1612 0 : const struct cred *old_cred = override_creds(iocb->fsync.creds);
1613 :
1614 0 : iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1615 0 : revert_creds(old_cred);
1616 0 : put_cred(iocb->fsync.creds);
1617 0 : iocb_put(iocb);
1618 0 : }
1619 :
1620 0 : static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1621 : bool datasync)
1622 : {
1623 0 : if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1624 : iocb->aio_rw_flags))
1625 : return -EINVAL;
1626 :
1627 0 : if (unlikely(!req->file->f_op->fsync))
1628 : return -EINVAL;
1629 :
1630 0 : req->creds = prepare_creds();
1631 0 : if (!req->creds)
1632 : return -ENOMEM;
1633 :
1634 0 : req->datasync = datasync;
1635 0 : INIT_WORK(&req->work, aio_fsync_work);
1636 0 : schedule_work(&req->work);
1637 0 : return 0;
1638 : }
1639 :
1640 0 : static void aio_poll_put_work(struct work_struct *work)
1641 : {
1642 0 : struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1643 0 : struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1644 :
1645 0 : iocb_put(iocb);
1646 0 : }
1647 :
1648 : /*
1649 : * Safely lock the waitqueue which the request is on, synchronizing with the
1650 : * case where the ->poll() provider decides to free its waitqueue early.
1651 : *
1652 : * Returns true on success, meaning that req->head->lock was locked, req->wait
1653 : * is on req->head, and an RCU read lock was taken. Returns false if the
1654 : * request was already removed from its waitqueue (which might no longer exist).
1655 : */
1656 : static bool poll_iocb_lock_wq(struct poll_iocb *req)
1657 : {
1658 : wait_queue_head_t *head;
1659 :
1660 : /*
1661 : * While we hold the waitqueue lock and the waitqueue is nonempty,
1662 : * wake_up_pollfree() will wait for us. However, taking the waitqueue
1663 : * lock in the first place can race with the waitqueue being freed.
1664 : *
1665 : * We solve this as eventpoll does: by taking advantage of the fact that
1666 : * all users of wake_up_pollfree() will RCU-delay the actual free. If
1667 : * we enter rcu_read_lock() and see that the pointer to the queue is
1668 : * non-NULL, we can then lock it without the memory being freed out from
1669 : * under us, then check whether the request is still on the queue.
1670 : *
1671 : * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1672 : * case the caller deletes the entry from the queue, leaving it empty.
1673 : * In that case, only RCU prevents the queue memory from being freed.
1674 : */
1675 : rcu_read_lock();
1676 0 : head = smp_load_acquire(&req->head);
1677 0 : if (head) {
1678 0 : spin_lock(&head->lock);
1679 0 : if (!list_empty(&req->wait.entry))
1680 : return true;
1681 0 : spin_unlock(&head->lock);
1682 : }
1683 : rcu_read_unlock();
1684 : return false;
1685 : }
1686 :
1687 : static void poll_iocb_unlock_wq(struct poll_iocb *req)
1688 : {
1689 0 : spin_unlock(&req->head->lock);
1690 : rcu_read_unlock();
1691 : }
1692 :
1693 0 : static void aio_poll_complete_work(struct work_struct *work)
1694 : {
1695 0 : struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1696 0 : struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1697 0 : struct poll_table_struct pt = { ._key = req->events };
1698 0 : struct kioctx *ctx = iocb->ki_ctx;
1699 0 : __poll_t mask = 0;
1700 :
1701 0 : if (!READ_ONCE(req->cancelled))
1702 0 : mask = vfs_poll(req->file, &pt) & req->events;
1703 :
1704 : /*
1705 : * Note that ->ki_cancel callers also delete iocb from active_reqs after
1706 : * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1707 : * synchronize with them. In the cancellation case the list_del_init
1708 : * itself is not actually needed, but harmless so we keep it in to
1709 : * avoid further branches in the fast path.
1710 : */
1711 0 : spin_lock_irq(&ctx->ctx_lock);
1712 0 : if (poll_iocb_lock_wq(req)) {
1713 0 : if (!mask && !READ_ONCE(req->cancelled)) {
1714 : /*
1715 : * The request isn't actually ready to be completed yet.
1716 : * Reschedule completion if another wakeup came in.
1717 : */
1718 0 : if (req->work_need_resched) {
1719 0 : schedule_work(&req->work);
1720 0 : req->work_need_resched = false;
1721 : } else {
1722 0 : req->work_scheduled = false;
1723 : }
1724 0 : poll_iocb_unlock_wq(req);
1725 0 : spin_unlock_irq(&ctx->ctx_lock);
1726 0 : return;
1727 : }
1728 0 : list_del_init(&req->wait.entry);
1729 0 : poll_iocb_unlock_wq(req);
1730 : } /* else, POLLFREE has freed the waitqueue, so we must complete */
1731 0 : list_del_init(&iocb->ki_list);
1732 0 : iocb->ki_res.res = mangle_poll(mask);
1733 0 : spin_unlock_irq(&ctx->ctx_lock);
1734 :
1735 0 : iocb_put(iocb);
1736 : }
1737 :
1738 : /* assumes we are called with irqs disabled */
1739 0 : static int aio_poll_cancel(struct kiocb *iocb)
1740 : {
1741 0 : struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1742 0 : struct poll_iocb *req = &aiocb->poll;
1743 :
1744 0 : if (poll_iocb_lock_wq(req)) {
1745 0 : WRITE_ONCE(req->cancelled, true);
1746 0 : if (!req->work_scheduled) {
1747 0 : schedule_work(&aiocb->poll.work);
1748 0 : req->work_scheduled = true;
1749 : }
1750 0 : poll_iocb_unlock_wq(req);
1751 : } /* else, the request was force-cancelled by POLLFREE already */
1752 :
1753 0 : return 0;
1754 : }
1755 :
1756 0 : static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1757 : void *key)
1758 : {
1759 0 : struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1760 0 : struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1761 0 : __poll_t mask = key_to_poll(key);
1762 : unsigned long flags;
1763 :
1764 : /* for instances that support it check for an event match first: */
1765 0 : if (mask && !(mask & req->events))
1766 : return 0;
1767 :
1768 : /*
1769 : * Complete the request inline if possible. This requires that three
1770 : * conditions be met:
1771 : * 1. An event mask must have been passed. If a plain wakeup was done
1772 : * instead, then mask == 0 and we have to call vfs_poll() to get
1773 : * the events, so inline completion isn't possible.
1774 : * 2. The completion work must not have already been scheduled.
1775 : * 3. ctx_lock must not be busy. We have to use trylock because we
1776 : * already hold the waitqueue lock, so this inverts the normal
1777 : * locking order. Use irqsave/irqrestore because not all
1778 : * filesystems (e.g. fuse) call this function with IRQs disabled,
1779 : * yet IRQs have to be disabled before ctx_lock is obtained.
1780 : */
1781 0 : if (mask && !req->work_scheduled &&
1782 0 : spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1783 0 : struct kioctx *ctx = iocb->ki_ctx;
1784 :
1785 0 : list_del_init(&req->wait.entry);
1786 0 : list_del(&iocb->ki_list);
1787 0 : iocb->ki_res.res = mangle_poll(mask);
1788 0 : if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1789 0 : iocb = NULL;
1790 0 : INIT_WORK(&req->work, aio_poll_put_work);
1791 0 : schedule_work(&req->work);
1792 : }
1793 0 : spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1794 0 : if (iocb)
1795 0 : iocb_put(iocb);
1796 : } else {
1797 : /*
1798 : * Schedule the completion work if needed. If it was already
1799 : * scheduled, record that another wakeup came in.
1800 : *
1801 : * Don't remove the request from the waitqueue here, as it might
1802 : * not actually be complete yet (we won't know until vfs_poll()
1803 : * is called), and we must not miss any wakeups. POLLFREE is an
1804 : * exception to this; see below.
1805 : */
1806 0 : if (req->work_scheduled) {
1807 0 : req->work_need_resched = true;
1808 : } else {
1809 0 : schedule_work(&req->work);
1810 0 : req->work_scheduled = true;
1811 : }
1812 :
1813 : /*
1814 : * If the waitqueue is being freed early but we can't complete
1815 : * the request inline, we have to tear down the request as best
1816 : * we can. That means immediately removing the request from its
1817 : * waitqueue and preventing all further accesses to the
1818 : * waitqueue via the request. We also need to schedule the
1819 : * completion work (done above). Also mark the request as
1820 : * cancelled, to potentially skip an unneeded call to ->poll().
1821 : */
1822 0 : if (mask & POLLFREE) {
1823 0 : WRITE_ONCE(req->cancelled, true);
1824 0 : list_del_init(&req->wait.entry);
1825 :
1826 : /*
1827 : * Careful: this *must* be the last step, since as soon
1828 : * as req->head is NULL'ed out, the request can be
1829 : * completed and freed, since aio_poll_complete_work()
1830 : * will no longer need to take the waitqueue lock.
1831 : */
1832 0 : smp_store_release(&req->head, NULL);
1833 : }
1834 : }
1835 : return 1;
1836 : }
1837 :
1838 : struct aio_poll_table {
1839 : struct poll_table_struct pt;
1840 : struct aio_kiocb *iocb;
1841 : bool queued;
1842 : int error;
1843 : };
1844 :
1845 : static void
1846 0 : aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1847 : struct poll_table_struct *p)
1848 : {
1849 0 : struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1850 :
1851 : /* multiple wait queues per file are not supported */
1852 0 : if (unlikely(pt->queued)) {
1853 0 : pt->error = -EINVAL;
1854 0 : return;
1855 : }
1856 :
1857 0 : pt->queued = true;
1858 0 : pt->error = 0;
1859 0 : pt->iocb->poll.head = head;
1860 0 : add_wait_queue(head, &pt->iocb->poll.wait);
1861 : }
1862 :
1863 0 : static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1864 : {
1865 0 : struct kioctx *ctx = aiocb->ki_ctx;
1866 0 : struct poll_iocb *req = &aiocb->poll;
1867 : struct aio_poll_table apt;
1868 0 : bool cancel = false;
1869 : __poll_t mask;
1870 :
1871 : /* reject any unknown events outside the normal event mask. */
1872 0 : if ((u16)iocb->aio_buf != iocb->aio_buf)
1873 : return -EINVAL;
1874 : /* reject fields that are not defined for poll */
1875 0 : if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1876 : return -EINVAL;
1877 :
1878 0 : INIT_WORK(&req->work, aio_poll_complete_work);
1879 0 : req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1880 :
1881 0 : req->head = NULL;
1882 0 : req->cancelled = false;
1883 0 : req->work_scheduled = false;
1884 0 : req->work_need_resched = false;
1885 :
1886 0 : apt.pt._qproc = aio_poll_queue_proc;
1887 0 : apt.pt._key = req->events;
1888 0 : apt.iocb = aiocb;
1889 0 : apt.queued = false;
1890 0 : apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1891 :
1892 : /* initialized the list so that we can do list_empty checks */
1893 0 : INIT_LIST_HEAD(&req->wait.entry);
1894 0 : init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1895 :
1896 0 : mask = vfs_poll(req->file, &apt.pt) & req->events;
1897 0 : spin_lock_irq(&ctx->ctx_lock);
1898 0 : if (likely(apt.queued)) {
1899 0 : bool on_queue = poll_iocb_lock_wq(req);
1900 :
1901 0 : if (!on_queue || req->work_scheduled) {
1902 : /*
1903 : * aio_poll_wake() already either scheduled the async
1904 : * completion work, or completed the request inline.
1905 : */
1906 0 : if (apt.error) /* unsupported case: multiple queues */
1907 0 : cancel = true;
1908 0 : apt.error = 0;
1909 0 : mask = 0;
1910 : }
1911 0 : if (mask || apt.error) {
1912 : /* Steal to complete synchronously. */
1913 0 : list_del_init(&req->wait.entry);
1914 0 : } else if (cancel) {
1915 : /* Cancel if possible (may be too late though). */
1916 0 : WRITE_ONCE(req->cancelled, true);
1917 0 : } else if (on_queue) {
1918 : /*
1919 : * Actually waiting for an event, so add the request to
1920 : * active_reqs so that it can be cancelled if needed.
1921 : */
1922 0 : list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1923 0 : aiocb->ki_cancel = aio_poll_cancel;
1924 : }
1925 0 : if (on_queue)
1926 0 : poll_iocb_unlock_wq(req);
1927 : }
1928 0 : if (mask) { /* no async, we'd stolen it */
1929 0 : aiocb->ki_res.res = mangle_poll(mask);
1930 0 : apt.error = 0;
1931 : }
1932 0 : spin_unlock_irq(&ctx->ctx_lock);
1933 0 : if (mask)
1934 0 : iocb_put(aiocb);
1935 0 : return apt.error;
1936 : }
1937 :
1938 0 : static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1939 : struct iocb __user *user_iocb, struct aio_kiocb *req,
1940 : bool compat)
1941 : {
1942 0 : req->ki_filp = fget(iocb->aio_fildes);
1943 0 : if (unlikely(!req->ki_filp))
1944 : return -EBADF;
1945 :
1946 0 : if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1947 : struct eventfd_ctx *eventfd;
1948 : /*
1949 : * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1950 : * instance of the file* now. The file descriptor must be
1951 : * an eventfd() fd, and will be signaled for each completed
1952 : * event using the eventfd_signal() function.
1953 : */
1954 0 : eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1955 0 : if (IS_ERR(eventfd))
1956 0 : return PTR_ERR(eventfd);
1957 :
1958 0 : req->ki_eventfd = eventfd;
1959 : }
1960 :
1961 0 : if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1962 : pr_debug("EFAULT: aio_key\n");
1963 : return -EFAULT;
1964 : }
1965 :
1966 0 : req->ki_res.obj = (u64)(unsigned long)user_iocb;
1967 0 : req->ki_res.data = iocb->aio_data;
1968 0 : req->ki_res.res = 0;
1969 0 : req->ki_res.res2 = 0;
1970 :
1971 0 : switch (iocb->aio_lio_opcode) {
1972 : case IOCB_CMD_PREAD:
1973 0 : return aio_read(&req->rw, iocb, false, compat);
1974 : case IOCB_CMD_PWRITE:
1975 0 : return aio_write(&req->rw, iocb, false, compat);
1976 : case IOCB_CMD_PREADV:
1977 0 : return aio_read(&req->rw, iocb, true, compat);
1978 : case IOCB_CMD_PWRITEV:
1979 0 : return aio_write(&req->rw, iocb, true, compat);
1980 : case IOCB_CMD_FSYNC:
1981 0 : return aio_fsync(&req->fsync, iocb, false);
1982 : case IOCB_CMD_FDSYNC:
1983 0 : return aio_fsync(&req->fsync, iocb, true);
1984 : case IOCB_CMD_POLL:
1985 0 : return aio_poll(req, iocb);
1986 : default:
1987 : pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1988 : return -EINVAL;
1989 : }
1990 : }
1991 :
1992 0 : static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1993 : bool compat)
1994 : {
1995 : struct aio_kiocb *req;
1996 : struct iocb iocb;
1997 : int err;
1998 :
1999 0 : if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
2000 : return -EFAULT;
2001 :
2002 : /* enforce forwards compatibility on users */
2003 0 : if (unlikely(iocb.aio_reserved2)) {
2004 : pr_debug("EINVAL: reserve field set\n");
2005 : return -EINVAL;
2006 : }
2007 :
2008 : /* prevent overflows */
2009 0 : if (unlikely(
2010 : (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
2011 : (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
2012 : ((ssize_t)iocb.aio_nbytes < 0)
2013 : )) {
2014 : pr_debug("EINVAL: overflow check\n");
2015 : return -EINVAL;
2016 : }
2017 :
2018 0 : req = aio_get_req(ctx);
2019 0 : if (unlikely(!req))
2020 : return -EAGAIN;
2021 :
2022 0 : err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
2023 :
2024 : /* Done with the synchronous reference */
2025 0 : iocb_put(req);
2026 :
2027 : /*
2028 : * If err is 0, we'd either done aio_complete() ourselves or have
2029 : * arranged for that to be done asynchronously. Anything non-zero
2030 : * means that we need to destroy req ourselves.
2031 : */
2032 0 : if (unlikely(err)) {
2033 0 : iocb_destroy(req);
2034 0 : put_reqs_available(ctx, 1);
2035 : }
2036 : return err;
2037 : }
2038 :
2039 : /* sys_io_submit:
2040 : * Queue the nr iocbs pointed to by iocbpp for processing. Returns
2041 : * the number of iocbs queued. May return -EINVAL if the aio_context
2042 : * specified by ctx_id is invalid, if nr is < 0, if the iocb at
2043 : * *iocbpp[0] is not properly initialized, if the operation specified
2044 : * is invalid for the file descriptor in the iocb. May fail with
2045 : * -EFAULT if any of the data structures point to invalid data. May
2046 : * fail with -EBADF if the file descriptor specified in the first
2047 : * iocb is invalid. May fail with -EAGAIN if insufficient resources
2048 : * are available to queue any iocbs. Will return 0 if nr is 0. Will
2049 : * fail with -ENOSYS if not implemented.
2050 : */
2051 0 : SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2052 : struct iocb __user * __user *, iocbpp)
2053 : {
2054 : struct kioctx *ctx;
2055 0 : long ret = 0;
2056 0 : int i = 0;
2057 : struct blk_plug plug;
2058 :
2059 0 : if (unlikely(nr < 0))
2060 : return -EINVAL;
2061 :
2062 0 : ctx = lookup_ioctx(ctx_id);
2063 0 : if (unlikely(!ctx)) {
2064 : pr_debug("EINVAL: invalid context id\n");
2065 : return -EINVAL;
2066 : }
2067 :
2068 0 : if (nr > ctx->nr_events)
2069 0 : nr = ctx->nr_events;
2070 :
2071 0 : if (nr > AIO_PLUG_THRESHOLD)
2072 0 : blk_start_plug(&plug);
2073 0 : for (i = 0; i < nr; i++) {
2074 : struct iocb __user *user_iocb;
2075 :
2076 0 : if (unlikely(get_user(user_iocb, iocbpp + i))) {
2077 : ret = -EFAULT;
2078 : break;
2079 : }
2080 :
2081 0 : ret = io_submit_one(ctx, user_iocb, false);
2082 0 : if (ret)
2083 : break;
2084 : }
2085 0 : if (nr > AIO_PLUG_THRESHOLD)
2086 0 : blk_finish_plug(&plug);
2087 :
2088 0 : percpu_ref_put(&ctx->users);
2089 0 : return i ? i : ret;
2090 : }
2091 :
2092 : #ifdef CONFIG_COMPAT
2093 : COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2094 : int, nr, compat_uptr_t __user *, iocbpp)
2095 : {
2096 : struct kioctx *ctx;
2097 : long ret = 0;
2098 : int i = 0;
2099 : struct blk_plug plug;
2100 :
2101 : if (unlikely(nr < 0))
2102 : return -EINVAL;
2103 :
2104 : ctx = lookup_ioctx(ctx_id);
2105 : if (unlikely(!ctx)) {
2106 : pr_debug("EINVAL: invalid context id\n");
2107 : return -EINVAL;
2108 : }
2109 :
2110 : if (nr > ctx->nr_events)
2111 : nr = ctx->nr_events;
2112 :
2113 : if (nr > AIO_PLUG_THRESHOLD)
2114 : blk_start_plug(&plug);
2115 : for (i = 0; i < nr; i++) {
2116 : compat_uptr_t user_iocb;
2117 :
2118 : if (unlikely(get_user(user_iocb, iocbpp + i))) {
2119 : ret = -EFAULT;
2120 : break;
2121 : }
2122 :
2123 : ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2124 : if (ret)
2125 : break;
2126 : }
2127 : if (nr > AIO_PLUG_THRESHOLD)
2128 : blk_finish_plug(&plug);
2129 :
2130 : percpu_ref_put(&ctx->users);
2131 : return i ? i : ret;
2132 : }
2133 : #endif
2134 :
2135 : /* sys_io_cancel:
2136 : * Attempts to cancel an iocb previously passed to io_submit. If
2137 : * the operation is successfully cancelled, the resulting event is
2138 : * copied into the memory pointed to by result without being placed
2139 : * into the completion queue and 0 is returned. May fail with
2140 : * -EFAULT if any of the data structures pointed to are invalid.
2141 : * May fail with -EINVAL if aio_context specified by ctx_id is
2142 : * invalid. May fail with -EAGAIN if the iocb specified was not
2143 : * cancelled. Will fail with -ENOSYS if not implemented.
2144 : */
2145 0 : SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2146 : struct io_event __user *, result)
2147 : {
2148 : struct kioctx *ctx;
2149 : struct aio_kiocb *kiocb;
2150 0 : int ret = -EINVAL;
2151 : u32 key;
2152 0 : u64 obj = (u64)(unsigned long)iocb;
2153 :
2154 0 : if (unlikely(get_user(key, &iocb->aio_key)))
2155 : return -EFAULT;
2156 0 : if (unlikely(key != KIOCB_KEY))
2157 : return -EINVAL;
2158 :
2159 0 : ctx = lookup_ioctx(ctx_id);
2160 0 : if (unlikely(!ctx))
2161 : return -EINVAL;
2162 :
2163 0 : spin_lock_irq(&ctx->ctx_lock);
2164 : /* TODO: use a hash or array, this sucks. */
2165 0 : list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2166 0 : if (kiocb->ki_res.obj == obj) {
2167 0 : ret = kiocb->ki_cancel(&kiocb->rw);
2168 0 : list_del_init(&kiocb->ki_list);
2169 : break;
2170 : }
2171 : }
2172 0 : spin_unlock_irq(&ctx->ctx_lock);
2173 :
2174 0 : if (!ret) {
2175 : /*
2176 : * The result argument is no longer used - the io_event is
2177 : * always delivered via the ring buffer. -EINPROGRESS indicates
2178 : * cancellation is progress:
2179 : */
2180 0 : ret = -EINPROGRESS;
2181 : }
2182 :
2183 0 : percpu_ref_put(&ctx->users);
2184 :
2185 0 : return ret;
2186 : }
2187 :
2188 0 : static long do_io_getevents(aio_context_t ctx_id,
2189 : long min_nr,
2190 : long nr,
2191 : struct io_event __user *events,
2192 : struct timespec64 *ts)
2193 : {
2194 0 : ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2195 0 : struct kioctx *ioctx = lookup_ioctx(ctx_id);
2196 0 : long ret = -EINVAL;
2197 :
2198 0 : if (likely(ioctx)) {
2199 0 : if (likely(min_nr <= nr && min_nr >= 0))
2200 0 : ret = read_events(ioctx, min_nr, nr, events, until);
2201 0 : percpu_ref_put(&ioctx->users);
2202 : }
2203 :
2204 0 : return ret;
2205 : }
2206 :
2207 : /* io_getevents:
2208 : * Attempts to read at least min_nr events and up to nr events from
2209 : * the completion queue for the aio_context specified by ctx_id. If
2210 : * it succeeds, the number of read events is returned. May fail with
2211 : * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2212 : * out of range, if timeout is out of range. May fail with -EFAULT
2213 : * if any of the memory specified is invalid. May return 0 or
2214 : * < min_nr if the timeout specified by timeout has elapsed
2215 : * before sufficient events are available, where timeout == NULL
2216 : * specifies an infinite timeout. Note that the timeout pointed to by
2217 : * timeout is relative. Will fail with -ENOSYS if not implemented.
2218 : */
2219 : #ifdef CONFIG_64BIT
2220 :
2221 0 : SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2222 : long, min_nr,
2223 : long, nr,
2224 : struct io_event __user *, events,
2225 : struct __kernel_timespec __user *, timeout)
2226 : {
2227 : struct timespec64 ts;
2228 : int ret;
2229 :
2230 0 : if (timeout && unlikely(get_timespec64(&ts, timeout)))
2231 : return -EFAULT;
2232 :
2233 0 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2234 0 : if (!ret && signal_pending(current))
2235 0 : ret = -EINTR;
2236 0 : return ret;
2237 : }
2238 :
2239 : #endif
2240 :
2241 : struct __aio_sigset {
2242 : const sigset_t __user *sigmask;
2243 : size_t sigsetsize;
2244 : };
2245 :
2246 0 : SYSCALL_DEFINE6(io_pgetevents,
2247 : aio_context_t, ctx_id,
2248 : long, min_nr,
2249 : long, nr,
2250 : struct io_event __user *, events,
2251 : struct __kernel_timespec __user *, timeout,
2252 : const struct __aio_sigset __user *, usig)
2253 : {
2254 0 : struct __aio_sigset ksig = { NULL, };
2255 : struct timespec64 ts;
2256 : bool interrupted;
2257 : int ret;
2258 :
2259 0 : if (timeout && unlikely(get_timespec64(&ts, timeout)))
2260 : return -EFAULT;
2261 :
2262 0 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2263 : return -EFAULT;
2264 :
2265 0 : ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2266 0 : if (ret)
2267 0 : return ret;
2268 :
2269 0 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2270 :
2271 0 : interrupted = signal_pending(current);
2272 0 : restore_saved_sigmask_unless(interrupted);
2273 0 : if (interrupted && !ret)
2274 0 : ret = -ERESTARTNOHAND;
2275 :
2276 0 : return ret;
2277 : }
2278 :
2279 : #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2280 :
2281 : SYSCALL_DEFINE6(io_pgetevents_time32,
2282 : aio_context_t, ctx_id,
2283 : long, min_nr,
2284 : long, nr,
2285 : struct io_event __user *, events,
2286 : struct old_timespec32 __user *, timeout,
2287 : const struct __aio_sigset __user *, usig)
2288 : {
2289 : struct __aio_sigset ksig = { NULL, };
2290 : struct timespec64 ts;
2291 : bool interrupted;
2292 : int ret;
2293 :
2294 : if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2295 : return -EFAULT;
2296 :
2297 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2298 : return -EFAULT;
2299 :
2300 :
2301 : ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2302 : if (ret)
2303 : return ret;
2304 :
2305 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2306 :
2307 : interrupted = signal_pending(current);
2308 : restore_saved_sigmask_unless(interrupted);
2309 : if (interrupted && !ret)
2310 : ret = -ERESTARTNOHAND;
2311 :
2312 : return ret;
2313 : }
2314 :
2315 : #endif
2316 :
2317 : #if defined(CONFIG_COMPAT_32BIT_TIME)
2318 :
2319 : SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2320 : __s32, min_nr,
2321 : __s32, nr,
2322 : struct io_event __user *, events,
2323 : struct old_timespec32 __user *, timeout)
2324 : {
2325 : struct timespec64 t;
2326 : int ret;
2327 :
2328 : if (timeout && get_old_timespec32(&t, timeout))
2329 : return -EFAULT;
2330 :
2331 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2332 : if (!ret && signal_pending(current))
2333 : ret = -EINTR;
2334 : return ret;
2335 : }
2336 :
2337 : #endif
2338 :
2339 : #ifdef CONFIG_COMPAT
2340 :
2341 : struct __compat_aio_sigset {
2342 : compat_uptr_t sigmask;
2343 : compat_size_t sigsetsize;
2344 : };
2345 :
2346 : #if defined(CONFIG_COMPAT_32BIT_TIME)
2347 :
2348 : COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2349 : compat_aio_context_t, ctx_id,
2350 : compat_long_t, min_nr,
2351 : compat_long_t, nr,
2352 : struct io_event __user *, events,
2353 : struct old_timespec32 __user *, timeout,
2354 : const struct __compat_aio_sigset __user *, usig)
2355 : {
2356 : struct __compat_aio_sigset ksig = { 0, };
2357 : struct timespec64 t;
2358 : bool interrupted;
2359 : int ret;
2360 :
2361 : if (timeout && get_old_timespec32(&t, timeout))
2362 : return -EFAULT;
2363 :
2364 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2365 : return -EFAULT;
2366 :
2367 : ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2368 : if (ret)
2369 : return ret;
2370 :
2371 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2372 :
2373 : interrupted = signal_pending(current);
2374 : restore_saved_sigmask_unless(interrupted);
2375 : if (interrupted && !ret)
2376 : ret = -ERESTARTNOHAND;
2377 :
2378 : return ret;
2379 : }
2380 :
2381 : #endif
2382 :
2383 : COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2384 : compat_aio_context_t, ctx_id,
2385 : compat_long_t, min_nr,
2386 : compat_long_t, nr,
2387 : struct io_event __user *, events,
2388 : struct __kernel_timespec __user *, timeout,
2389 : const struct __compat_aio_sigset __user *, usig)
2390 : {
2391 : struct __compat_aio_sigset ksig = { 0, };
2392 : struct timespec64 t;
2393 : bool interrupted;
2394 : int ret;
2395 :
2396 : if (timeout && get_timespec64(&t, timeout))
2397 : return -EFAULT;
2398 :
2399 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2400 : return -EFAULT;
2401 :
2402 : ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2403 : if (ret)
2404 : return ret;
2405 :
2406 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2407 :
2408 : interrupted = signal_pending(current);
2409 : restore_saved_sigmask_unless(interrupted);
2410 : if (interrupted && !ret)
2411 : ret = -ERESTARTNOHAND;
2412 :
2413 : return ret;
2414 : }
2415 : #endif
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