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 : if (!table)
365 : goto out_unlock;
366 :
367 0 : for (i = 0; i < table->nr; i++) {
368 : struct kioctx *ctx;
369 :
370 0 : ctx = rcu_dereference(table->table[i]);
371 0 : if (ctx && ctx->aio_ring_file == file) {
372 0 : if (!atomic_read(&ctx->dead)) {
373 0 : ctx->user_id = ctx->mmap_base = vma->vm_start;
374 0 : res = 0;
375 : }
376 : break;
377 : }
378 : }
379 :
380 : out_unlock:
381 : rcu_read_unlock();
382 0 : spin_unlock(&mm->ioctx_lock);
383 0 : return res;
384 : }
385 :
386 : static const struct vm_operations_struct aio_ring_vm_ops = {
387 : .mremap = aio_ring_mremap,
388 : #if IS_ENABLED(CONFIG_MMU)
389 : .fault = filemap_fault,
390 : .map_pages = filemap_map_pages,
391 : .page_mkwrite = filemap_page_mkwrite,
392 : #endif
393 : };
394 :
395 0 : static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
396 : {
397 0 : vm_flags_set(vma, VM_DONTEXPAND);
398 0 : vma->vm_ops = &aio_ring_vm_ops;
399 0 : return 0;
400 : }
401 :
402 : static const struct file_operations aio_ring_fops = {
403 : .mmap = aio_ring_mmap,
404 : };
405 :
406 : #if IS_ENABLED(CONFIG_MIGRATION)
407 0 : static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
408 : struct folio *src, enum migrate_mode mode)
409 : {
410 : struct kioctx *ctx;
411 : unsigned long flags;
412 : pgoff_t idx;
413 : int rc;
414 :
415 : /*
416 : * We cannot support the _NO_COPY case here, because copy needs to
417 : * happen under the ctx->completion_lock. That does not work with the
418 : * migration workflow of MIGRATE_SYNC_NO_COPY.
419 : */
420 0 : if (mode == MIGRATE_SYNC_NO_COPY)
421 : return -EINVAL;
422 :
423 0 : rc = 0;
424 :
425 : /* mapping->private_lock here protects against the kioctx teardown. */
426 0 : spin_lock(&mapping->private_lock);
427 0 : ctx = mapping->private_data;
428 0 : if (!ctx) {
429 : rc = -EINVAL;
430 : goto out;
431 : }
432 :
433 : /* The ring_lock mutex. The prevents aio_read_events() from writing
434 : * to the ring's head, and prevents page migration from mucking in
435 : * a partially initialized kiotx.
436 : */
437 0 : if (!mutex_trylock(&ctx->ring_lock)) {
438 : rc = -EAGAIN;
439 : goto out;
440 : }
441 :
442 0 : idx = src->index;
443 0 : if (idx < (pgoff_t)ctx->nr_pages) {
444 : /* Make sure the old folio hasn't already been changed */
445 0 : if (ctx->ring_pages[idx] != &src->page)
446 0 : rc = -EAGAIN;
447 : } else
448 : rc = -EINVAL;
449 :
450 0 : if (rc != 0)
451 : goto out_unlock;
452 :
453 : /* Writeback must be complete */
454 0 : BUG_ON(folio_test_writeback(src));
455 0 : folio_get(dst);
456 :
457 0 : rc = folio_migrate_mapping(mapping, dst, src, 1);
458 0 : if (rc != MIGRATEPAGE_SUCCESS) {
459 : folio_put(dst);
460 : goto out_unlock;
461 : }
462 :
463 : /* Take completion_lock to prevent other writes to the ring buffer
464 : * while the old folio is copied to the new. This prevents new
465 : * events from being lost.
466 : */
467 0 : spin_lock_irqsave(&ctx->completion_lock, flags);
468 0 : folio_migrate_copy(dst, src);
469 0 : BUG_ON(ctx->ring_pages[idx] != &src->page);
470 0 : ctx->ring_pages[idx] = &dst->page;
471 0 : spin_unlock_irqrestore(&ctx->completion_lock, flags);
472 :
473 : /* The old folio is no longer accessible. */
474 : folio_put(src);
475 :
476 : out_unlock:
477 0 : mutex_unlock(&ctx->ring_lock);
478 : out:
479 0 : spin_unlock(&mapping->private_lock);
480 0 : return rc;
481 : }
482 : #else
483 : #define aio_migrate_folio NULL
484 : #endif
485 :
486 : static const struct address_space_operations aio_ctx_aops = {
487 : .dirty_folio = noop_dirty_folio,
488 : .migrate_folio = aio_migrate_folio,
489 : };
490 :
491 0 : static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
492 : {
493 : struct aio_ring *ring;
494 0 : struct mm_struct *mm = current->mm;
495 : unsigned long size, unused;
496 : int nr_pages;
497 : int i;
498 : struct file *file;
499 :
500 : /* Compensate for the ring buffer's head/tail overlap entry */
501 0 : nr_events += 2; /* 1 is required, 2 for good luck */
502 :
503 0 : size = sizeof(struct aio_ring);
504 0 : size += sizeof(struct io_event) * nr_events;
505 :
506 0 : nr_pages = PFN_UP(size);
507 0 : if (nr_pages < 0)
508 : return -EINVAL;
509 :
510 0 : file = aio_private_file(ctx, nr_pages);
511 0 : if (IS_ERR(file)) {
512 0 : ctx->aio_ring_file = NULL;
513 0 : return -ENOMEM;
514 : }
515 :
516 0 : ctx->aio_ring_file = file;
517 0 : nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
518 0 : / sizeof(struct io_event);
519 :
520 0 : ctx->ring_pages = ctx->internal_pages;
521 0 : if (nr_pages > AIO_RING_PAGES) {
522 0 : ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
523 : GFP_KERNEL);
524 0 : if (!ctx->ring_pages) {
525 0 : put_aio_ring_file(ctx);
526 0 : return -ENOMEM;
527 : }
528 : }
529 :
530 0 : for (i = 0; i < nr_pages; i++) {
531 : struct page *page;
532 0 : page = find_or_create_page(file->f_mapping,
533 : i, GFP_HIGHUSER | __GFP_ZERO);
534 0 : if (!page)
535 : break;
536 0 : pr_debug("pid(%d) page[%d]->count=%d\n",
537 : current->pid, i, page_count(page));
538 0 : SetPageUptodate(page);
539 0 : unlock_page(page);
540 :
541 0 : ctx->ring_pages[i] = page;
542 : }
543 0 : ctx->nr_pages = i;
544 :
545 0 : if (unlikely(i != nr_pages)) {
546 0 : aio_free_ring(ctx);
547 0 : return -ENOMEM;
548 : }
549 :
550 0 : ctx->mmap_size = nr_pages * PAGE_SIZE;
551 0 : pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
552 :
553 0 : if (mmap_write_lock_killable(mm)) {
554 0 : ctx->mmap_size = 0;
555 0 : aio_free_ring(ctx);
556 0 : return -EINTR;
557 : }
558 :
559 0 : ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
560 : PROT_READ | PROT_WRITE,
561 : MAP_SHARED, 0, &unused, NULL);
562 0 : mmap_write_unlock(mm);
563 0 : if (IS_ERR((void *)ctx->mmap_base)) {
564 0 : ctx->mmap_size = 0;
565 0 : aio_free_ring(ctx);
566 0 : return -ENOMEM;
567 : }
568 :
569 : pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
570 :
571 0 : ctx->user_id = ctx->mmap_base;
572 0 : ctx->nr_events = nr_events; /* trusted copy */
573 :
574 0 : ring = kmap_atomic(ctx->ring_pages[0]);
575 0 : ring->nr = nr_events; /* user copy */
576 0 : ring->id = ~0U;
577 0 : ring->head = ring->tail = 0;
578 0 : ring->magic = AIO_RING_MAGIC;
579 0 : ring->compat_features = AIO_RING_COMPAT_FEATURES;
580 0 : ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
581 0 : ring->header_length = sizeof(struct aio_ring);
582 0 : kunmap_atomic(ring);
583 0 : flush_dcache_page(ctx->ring_pages[0]);
584 :
585 0 : return 0;
586 : }
587 :
588 : #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
589 : #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
590 : #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
591 :
592 0 : void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
593 : {
594 0 : struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
595 0 : struct kioctx *ctx = req->ki_ctx;
596 : unsigned long flags;
597 :
598 0 : if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
599 : return;
600 :
601 0 : spin_lock_irqsave(&ctx->ctx_lock, flags);
602 0 : list_add_tail(&req->ki_list, &ctx->active_reqs);
603 0 : req->ki_cancel = cancel;
604 0 : spin_unlock_irqrestore(&ctx->ctx_lock, flags);
605 : }
606 : EXPORT_SYMBOL(kiocb_set_cancel_fn);
607 :
608 : /*
609 : * free_ioctx() should be RCU delayed to synchronize against the RCU
610 : * protected lookup_ioctx() and also needs process context to call
611 : * aio_free_ring(). Use rcu_work.
612 : */
613 0 : static void free_ioctx(struct work_struct *work)
614 : {
615 0 : struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
616 : free_rwork);
617 : pr_debug("freeing %p\n", ctx);
618 :
619 0 : aio_free_ring(ctx);
620 0 : free_percpu(ctx->cpu);
621 0 : percpu_ref_exit(&ctx->reqs);
622 0 : percpu_ref_exit(&ctx->users);
623 0 : kmem_cache_free(kioctx_cachep, ctx);
624 0 : }
625 :
626 0 : static void free_ioctx_reqs(struct percpu_ref *ref)
627 : {
628 0 : struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
629 :
630 : /* At this point we know that there are no any in-flight requests */
631 0 : if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
632 0 : complete(&ctx->rq_wait->comp);
633 :
634 : /* Synchronize against RCU protected table->table[] dereferences */
635 0 : INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
636 0 : queue_rcu_work(system_wq, &ctx->free_rwork);
637 0 : }
638 :
639 : /*
640 : * When this function runs, the kioctx has been removed from the "hash table"
641 : * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
642 : * now it's safe to cancel any that need to be.
643 : */
644 0 : static void free_ioctx_users(struct percpu_ref *ref)
645 : {
646 0 : struct kioctx *ctx = container_of(ref, struct kioctx, users);
647 : struct aio_kiocb *req;
648 :
649 0 : spin_lock_irq(&ctx->ctx_lock);
650 :
651 0 : while (!list_empty(&ctx->active_reqs)) {
652 0 : req = list_first_entry(&ctx->active_reqs,
653 : struct aio_kiocb, ki_list);
654 0 : req->ki_cancel(&req->rw);
655 0 : list_del_init(&req->ki_list);
656 : }
657 :
658 0 : spin_unlock_irq(&ctx->ctx_lock);
659 :
660 0 : percpu_ref_kill(&ctx->reqs);
661 0 : percpu_ref_put(&ctx->reqs);
662 0 : }
663 :
664 0 : static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
665 : {
666 : unsigned i, new_nr;
667 : struct kioctx_table *table, *old;
668 : struct aio_ring *ring;
669 :
670 0 : spin_lock(&mm->ioctx_lock);
671 0 : table = rcu_dereference_raw(mm->ioctx_table);
672 :
673 : while (1) {
674 0 : if (table)
675 0 : for (i = 0; i < table->nr; i++)
676 0 : if (!rcu_access_pointer(table->table[i])) {
677 0 : ctx->id = i;
678 0 : rcu_assign_pointer(table->table[i], ctx);
679 0 : spin_unlock(&mm->ioctx_lock);
680 :
681 : /* While kioctx setup is in progress,
682 : * we are protected from page migration
683 : * changes ring_pages by ->ring_lock.
684 : */
685 0 : ring = kmap_atomic(ctx->ring_pages[0]);
686 0 : ring->id = ctx->id;
687 0 : kunmap_atomic(ring);
688 0 : return 0;
689 : }
690 :
691 0 : new_nr = (table ? table->nr : 1) * 4;
692 0 : spin_unlock(&mm->ioctx_lock);
693 :
694 0 : table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
695 0 : if (!table)
696 : return -ENOMEM;
697 :
698 0 : table->nr = new_nr;
699 :
700 0 : spin_lock(&mm->ioctx_lock);
701 0 : old = rcu_dereference_raw(mm->ioctx_table);
702 :
703 0 : if (!old) {
704 0 : rcu_assign_pointer(mm->ioctx_table, table);
705 0 : } else if (table->nr > old->nr) {
706 0 : memcpy(table->table, old->table,
707 0 : old->nr * sizeof(struct kioctx *));
708 :
709 0 : rcu_assign_pointer(mm->ioctx_table, table);
710 0 : kfree_rcu(old, rcu);
711 : } else {
712 0 : kfree(table);
713 0 : table = old;
714 : }
715 : }
716 : }
717 :
718 0 : static void aio_nr_sub(unsigned nr)
719 : {
720 0 : spin_lock(&aio_nr_lock);
721 0 : if (WARN_ON(aio_nr - nr > aio_nr))
722 0 : aio_nr = 0;
723 : else
724 0 : aio_nr -= nr;
725 0 : spin_unlock(&aio_nr_lock);
726 0 : }
727 :
728 : /* ioctx_alloc
729 : * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
730 : */
731 0 : static struct kioctx *ioctx_alloc(unsigned nr_events)
732 : {
733 0 : struct mm_struct *mm = current->mm;
734 : struct kioctx *ctx;
735 0 : int err = -ENOMEM;
736 :
737 : /*
738 : * Store the original nr_events -- what userspace passed to io_setup(),
739 : * for counting against the global limit -- before it changes.
740 : */
741 0 : unsigned int max_reqs = nr_events;
742 :
743 : /*
744 : * We keep track of the number of available ringbuffer slots, to prevent
745 : * overflow (reqs_available), and we also use percpu counters for this.
746 : *
747 : * So since up to half the slots might be on other cpu's percpu counters
748 : * and unavailable, double nr_events so userspace sees what they
749 : * expected: additionally, we move req_batch slots to/from percpu
750 : * counters at a time, so make sure that isn't 0:
751 : */
752 0 : nr_events = max(nr_events, num_possible_cpus() * 4);
753 0 : nr_events *= 2;
754 :
755 : /* Prevent overflows */
756 0 : if (nr_events > (0x10000000U / sizeof(struct io_event))) {
757 : pr_debug("ENOMEM: nr_events too high\n");
758 : return ERR_PTR(-EINVAL);
759 : }
760 :
761 0 : if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
762 : return ERR_PTR(-EAGAIN);
763 :
764 0 : ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
765 0 : if (!ctx)
766 : return ERR_PTR(-ENOMEM);
767 :
768 0 : ctx->max_reqs = max_reqs;
769 :
770 0 : spin_lock_init(&ctx->ctx_lock);
771 0 : spin_lock_init(&ctx->completion_lock);
772 0 : mutex_init(&ctx->ring_lock);
773 : /* Protect against page migration throughout kiotx setup by keeping
774 : * the ring_lock mutex held until setup is complete. */
775 0 : mutex_lock(&ctx->ring_lock);
776 0 : init_waitqueue_head(&ctx->wait);
777 :
778 0 : INIT_LIST_HEAD(&ctx->active_reqs);
779 :
780 0 : if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
781 : goto err;
782 :
783 0 : if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
784 : goto err;
785 :
786 0 : ctx->cpu = alloc_percpu(struct kioctx_cpu);
787 0 : if (!ctx->cpu)
788 : goto err;
789 :
790 0 : err = aio_setup_ring(ctx, nr_events);
791 0 : if (err < 0)
792 : goto err;
793 :
794 0 : atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
795 0 : ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
796 0 : if (ctx->req_batch < 1)
797 0 : ctx->req_batch = 1;
798 :
799 : /* limit the number of system wide aios */
800 0 : spin_lock(&aio_nr_lock);
801 0 : if (aio_nr + ctx->max_reqs > aio_max_nr ||
802 : aio_nr + ctx->max_reqs < aio_nr) {
803 0 : spin_unlock(&aio_nr_lock);
804 0 : err = -EAGAIN;
805 0 : goto err_ctx;
806 : }
807 0 : aio_nr += ctx->max_reqs;
808 0 : spin_unlock(&aio_nr_lock);
809 :
810 0 : percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
811 0 : percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
812 :
813 0 : err = ioctx_add_table(ctx, mm);
814 0 : if (err)
815 : goto err_cleanup;
816 :
817 : /* Release the ring_lock mutex now that all setup is complete. */
818 0 : mutex_unlock(&ctx->ring_lock);
819 :
820 : pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
821 : ctx, ctx->user_id, mm, ctx->nr_events);
822 0 : return ctx;
823 :
824 : err_cleanup:
825 0 : aio_nr_sub(ctx->max_reqs);
826 : err_ctx:
827 0 : atomic_set(&ctx->dead, 1);
828 0 : if (ctx->mmap_size)
829 0 : vm_munmap(ctx->mmap_base, ctx->mmap_size);
830 0 : aio_free_ring(ctx);
831 : err:
832 0 : mutex_unlock(&ctx->ring_lock);
833 0 : free_percpu(ctx->cpu);
834 0 : percpu_ref_exit(&ctx->reqs);
835 0 : percpu_ref_exit(&ctx->users);
836 0 : kmem_cache_free(kioctx_cachep, ctx);
837 : pr_debug("error allocating ioctx %d\n", err);
838 0 : return ERR_PTR(err);
839 : }
840 :
841 : /* kill_ioctx
842 : * Cancels all outstanding aio requests on an aio context. Used
843 : * when the processes owning a context have all exited to encourage
844 : * the rapid destruction of the kioctx.
845 : */
846 0 : static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
847 : struct ctx_rq_wait *wait)
848 : {
849 : struct kioctx_table *table;
850 :
851 0 : spin_lock(&mm->ioctx_lock);
852 0 : if (atomic_xchg(&ctx->dead, 1)) {
853 0 : spin_unlock(&mm->ioctx_lock);
854 0 : return -EINVAL;
855 : }
856 :
857 0 : table = rcu_dereference_raw(mm->ioctx_table);
858 0 : WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
859 0 : RCU_INIT_POINTER(table->table[ctx->id], NULL);
860 0 : spin_unlock(&mm->ioctx_lock);
861 :
862 : /* free_ioctx_reqs() will do the necessary RCU synchronization */
863 0 : wake_up_all(&ctx->wait);
864 :
865 : /*
866 : * It'd be more correct to do this in free_ioctx(), after all
867 : * the outstanding kiocbs have finished - but by then io_destroy
868 : * has already returned, so io_setup() could potentially return
869 : * -EAGAIN with no ioctxs actually in use (as far as userspace
870 : * could tell).
871 : */
872 0 : aio_nr_sub(ctx->max_reqs);
873 :
874 0 : if (ctx->mmap_size)
875 0 : vm_munmap(ctx->mmap_base, ctx->mmap_size);
876 :
877 0 : ctx->rq_wait = wait;
878 0 : percpu_ref_kill(&ctx->users);
879 0 : return 0;
880 : }
881 :
882 : /*
883 : * exit_aio: called when the last user of mm goes away. At this point, there is
884 : * no way for any new requests to be submited or any of the io_* syscalls to be
885 : * called on the context.
886 : *
887 : * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
888 : * them.
889 : */
890 0 : void exit_aio(struct mm_struct *mm)
891 : {
892 0 : struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
893 : struct ctx_rq_wait wait;
894 : int i, skipped;
895 :
896 0 : if (!table)
897 0 : return;
898 :
899 0 : atomic_set(&wait.count, table->nr);
900 0 : init_completion(&wait.comp);
901 :
902 0 : skipped = 0;
903 0 : for (i = 0; i < table->nr; ++i) {
904 0 : struct kioctx *ctx =
905 0 : rcu_dereference_protected(table->table[i], true);
906 :
907 0 : if (!ctx) {
908 0 : skipped++;
909 0 : continue;
910 : }
911 :
912 : /*
913 : * We don't need to bother with munmap() here - exit_mmap(mm)
914 : * is coming and it'll unmap everything. And we simply can't,
915 : * this is not necessarily our ->mm.
916 : * Since kill_ioctx() uses non-zero ->mmap_size as indicator
917 : * that it needs to unmap the area, just set it to 0.
918 : */
919 0 : ctx->mmap_size = 0;
920 0 : kill_ioctx(mm, ctx, &wait);
921 : }
922 :
923 0 : if (!atomic_sub_and_test(skipped, &wait.count)) {
924 : /* Wait until all IO for the context are done. */
925 0 : wait_for_completion(&wait.comp);
926 : }
927 :
928 0 : RCU_INIT_POINTER(mm->ioctx_table, NULL);
929 0 : kfree(table);
930 : }
931 :
932 0 : static void put_reqs_available(struct kioctx *ctx, unsigned nr)
933 : {
934 : struct kioctx_cpu *kcpu;
935 : unsigned long flags;
936 :
937 0 : local_irq_save(flags);
938 0 : kcpu = this_cpu_ptr(ctx->cpu);
939 0 : kcpu->reqs_available += nr;
940 :
941 0 : while (kcpu->reqs_available >= ctx->req_batch * 2) {
942 0 : kcpu->reqs_available -= ctx->req_batch;
943 0 : atomic_add(ctx->req_batch, &ctx->reqs_available);
944 : }
945 :
946 0 : local_irq_restore(flags);
947 0 : }
948 :
949 0 : static bool __get_reqs_available(struct kioctx *ctx)
950 : {
951 : struct kioctx_cpu *kcpu;
952 0 : bool ret = false;
953 : unsigned long flags;
954 :
955 0 : local_irq_save(flags);
956 0 : kcpu = this_cpu_ptr(ctx->cpu);
957 0 : if (!kcpu->reqs_available) {
958 0 : int avail = atomic_read(&ctx->reqs_available);
959 :
960 : do {
961 0 : if (avail < ctx->req_batch)
962 : goto out;
963 0 : } while (!atomic_try_cmpxchg(&ctx->reqs_available,
964 0 : &avail, avail - ctx->req_batch));
965 :
966 0 : kcpu->reqs_available += ctx->req_batch;
967 : }
968 :
969 0 : ret = true;
970 0 : kcpu->reqs_available--;
971 : out:
972 0 : local_irq_restore(flags);
973 0 : return ret;
974 : }
975 :
976 : /* refill_reqs_available
977 : * Updates the reqs_available reference counts used for tracking the
978 : * number of free slots in the completion ring. This can be called
979 : * from aio_complete() (to optimistically update reqs_available) or
980 : * from aio_get_req() (the we're out of events case). It must be
981 : * called holding ctx->completion_lock.
982 : */
983 0 : static void refill_reqs_available(struct kioctx *ctx, unsigned head,
984 : unsigned tail)
985 : {
986 : unsigned events_in_ring, completed;
987 :
988 : /* Clamp head since userland can write to it. */
989 0 : head %= ctx->nr_events;
990 0 : if (head <= tail)
991 0 : events_in_ring = tail - head;
992 : else
993 0 : events_in_ring = ctx->nr_events - (head - tail);
994 :
995 0 : completed = ctx->completed_events;
996 0 : if (events_in_ring < completed)
997 0 : completed -= events_in_ring;
998 : else
999 : completed = 0;
1000 :
1001 0 : if (!completed)
1002 : return;
1003 :
1004 0 : ctx->completed_events -= completed;
1005 0 : put_reqs_available(ctx, completed);
1006 : }
1007 :
1008 : /* user_refill_reqs_available
1009 : * Called to refill reqs_available when aio_get_req() encounters an
1010 : * out of space in the completion ring.
1011 : */
1012 0 : static void user_refill_reqs_available(struct kioctx *ctx)
1013 : {
1014 0 : spin_lock_irq(&ctx->completion_lock);
1015 0 : if (ctx->completed_events) {
1016 : struct aio_ring *ring;
1017 : unsigned head;
1018 :
1019 : /* Access of ring->head may race with aio_read_events_ring()
1020 : * here, but that's okay since whether we read the old version
1021 : * or the new version, and either will be valid. The important
1022 : * part is that head cannot pass tail since we prevent
1023 : * aio_complete() from updating tail by holding
1024 : * ctx->completion_lock. Even if head is invalid, the check
1025 : * against ctx->completed_events below will make sure we do the
1026 : * safe/right thing.
1027 : */
1028 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1029 0 : head = ring->head;
1030 0 : kunmap_atomic(ring);
1031 :
1032 0 : refill_reqs_available(ctx, head, ctx->tail);
1033 : }
1034 :
1035 0 : spin_unlock_irq(&ctx->completion_lock);
1036 0 : }
1037 :
1038 0 : static bool get_reqs_available(struct kioctx *ctx)
1039 : {
1040 0 : if (__get_reqs_available(ctx))
1041 : return true;
1042 0 : user_refill_reqs_available(ctx);
1043 0 : return __get_reqs_available(ctx);
1044 : }
1045 :
1046 : /* aio_get_req
1047 : * Allocate a slot for an aio request.
1048 : * Returns NULL if no requests are free.
1049 : *
1050 : * The refcount is initialized to 2 - one for the async op completion,
1051 : * one for the synchronous code that does this.
1052 : */
1053 0 : static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1054 : {
1055 : struct aio_kiocb *req;
1056 :
1057 0 : req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1058 0 : if (unlikely(!req))
1059 : return NULL;
1060 :
1061 0 : if (unlikely(!get_reqs_available(ctx))) {
1062 0 : kmem_cache_free(kiocb_cachep, req);
1063 0 : return NULL;
1064 : }
1065 :
1066 0 : percpu_ref_get(&ctx->reqs);
1067 0 : req->ki_ctx = ctx;
1068 0 : INIT_LIST_HEAD(&req->ki_list);
1069 0 : refcount_set(&req->ki_refcnt, 2);
1070 0 : req->ki_eventfd = NULL;
1071 0 : return req;
1072 : }
1073 :
1074 0 : static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1075 : {
1076 0 : struct aio_ring __user *ring = (void __user *)ctx_id;
1077 0 : struct mm_struct *mm = current->mm;
1078 0 : struct kioctx *ctx, *ret = NULL;
1079 : struct kioctx_table *table;
1080 : unsigned id;
1081 :
1082 0 : if (get_user(id, &ring->id))
1083 : return NULL;
1084 :
1085 : rcu_read_lock();
1086 0 : table = rcu_dereference(mm->ioctx_table);
1087 :
1088 0 : if (!table || id >= table->nr)
1089 : goto out;
1090 :
1091 0 : id = array_index_nospec(id, table->nr);
1092 0 : ctx = rcu_dereference(table->table[id]);
1093 0 : if (ctx && ctx->user_id == ctx_id) {
1094 0 : if (percpu_ref_tryget_live(&ctx->users))
1095 0 : ret = ctx;
1096 : }
1097 : out:
1098 : rcu_read_unlock();
1099 0 : return ret;
1100 : }
1101 :
1102 0 : static inline void iocb_destroy(struct aio_kiocb *iocb)
1103 : {
1104 0 : if (iocb->ki_eventfd)
1105 0 : eventfd_ctx_put(iocb->ki_eventfd);
1106 0 : if (iocb->ki_filp)
1107 0 : fput(iocb->ki_filp);
1108 0 : percpu_ref_put(&iocb->ki_ctx->reqs);
1109 0 : kmem_cache_free(kiocb_cachep, iocb);
1110 0 : }
1111 :
1112 : /* aio_complete
1113 : * Called when the io request on the given iocb is complete.
1114 : */
1115 0 : static void aio_complete(struct aio_kiocb *iocb)
1116 : {
1117 0 : struct kioctx *ctx = iocb->ki_ctx;
1118 : struct aio_ring *ring;
1119 : struct io_event *ev_page, *event;
1120 : unsigned tail, pos, head;
1121 : unsigned long flags;
1122 :
1123 : /*
1124 : * Add a completion event to the ring buffer. Must be done holding
1125 : * ctx->completion_lock to prevent other code from messing with the tail
1126 : * pointer since we might be called from irq context.
1127 : */
1128 0 : spin_lock_irqsave(&ctx->completion_lock, flags);
1129 :
1130 0 : tail = ctx->tail;
1131 0 : pos = tail + AIO_EVENTS_OFFSET;
1132 :
1133 0 : if (++tail >= ctx->nr_events)
1134 0 : tail = 0;
1135 :
1136 0 : ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1137 0 : event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1138 :
1139 0 : *event = iocb->ki_res;
1140 :
1141 0 : kunmap_atomic(ev_page);
1142 0 : flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1143 :
1144 : pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1145 : (void __user *)(unsigned long)iocb->ki_res.obj,
1146 : iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1147 :
1148 : /* after flagging the request as done, we
1149 : * must never even look at it again
1150 : */
1151 0 : smp_wmb(); /* make event visible before updating tail */
1152 :
1153 0 : ctx->tail = tail;
1154 :
1155 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1156 0 : head = ring->head;
1157 0 : ring->tail = tail;
1158 0 : kunmap_atomic(ring);
1159 0 : flush_dcache_page(ctx->ring_pages[0]);
1160 :
1161 0 : ctx->completed_events++;
1162 0 : if (ctx->completed_events > 1)
1163 0 : refill_reqs_available(ctx, head, tail);
1164 0 : spin_unlock_irqrestore(&ctx->completion_lock, flags);
1165 :
1166 : pr_debug("added to ring %p at [%u]\n", iocb, tail);
1167 :
1168 : /*
1169 : * Check if the user asked us to deliver the result through an
1170 : * eventfd. The eventfd_signal() function is safe to be called
1171 : * from IRQ context.
1172 : */
1173 0 : if (iocb->ki_eventfd)
1174 0 : eventfd_signal(iocb->ki_eventfd, 1);
1175 :
1176 : /*
1177 : * We have to order our ring_info tail store above and test
1178 : * of the wait list below outside the wait lock. This is
1179 : * like in wake_up_bit() where clearing a bit has to be
1180 : * ordered with the unlocked test.
1181 : */
1182 0 : smp_mb();
1183 :
1184 0 : if (waitqueue_active(&ctx->wait))
1185 0 : wake_up(&ctx->wait);
1186 0 : }
1187 :
1188 0 : static inline void iocb_put(struct aio_kiocb *iocb)
1189 : {
1190 0 : if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1191 0 : aio_complete(iocb);
1192 0 : iocb_destroy(iocb);
1193 : }
1194 0 : }
1195 :
1196 : /* aio_read_events_ring
1197 : * Pull an event off of the ioctx's event ring. Returns the number of
1198 : * events fetched
1199 : */
1200 0 : static long aio_read_events_ring(struct kioctx *ctx,
1201 : struct io_event __user *event, long nr)
1202 : {
1203 : struct aio_ring *ring;
1204 : unsigned head, tail, pos;
1205 0 : long ret = 0;
1206 : int copy_ret;
1207 :
1208 : /*
1209 : * The mutex can block and wake us up and that will cause
1210 : * wait_event_interruptible_hrtimeout() to schedule without sleeping
1211 : * and repeat. This should be rare enough that it doesn't cause
1212 : * peformance issues. See the comment in read_events() for more detail.
1213 : */
1214 : sched_annotate_sleep();
1215 0 : mutex_lock(&ctx->ring_lock);
1216 :
1217 : /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1218 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1219 0 : head = ring->head;
1220 0 : tail = ring->tail;
1221 0 : kunmap_atomic(ring);
1222 :
1223 : /*
1224 : * Ensure that once we've read the current tail pointer, that
1225 : * we also see the events that were stored up to the tail.
1226 : */
1227 0 : smp_rmb();
1228 :
1229 : pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1230 :
1231 0 : if (head == tail)
1232 : goto out;
1233 :
1234 0 : head %= ctx->nr_events;
1235 0 : tail %= ctx->nr_events;
1236 :
1237 0 : while (ret < nr) {
1238 : long avail;
1239 : struct io_event *ev;
1240 : struct page *page;
1241 :
1242 0 : avail = (head <= tail ? tail : ctx->nr_events) - head;
1243 0 : if (head == tail)
1244 : break;
1245 :
1246 0 : pos = head + AIO_EVENTS_OFFSET;
1247 0 : page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1248 0 : pos %= AIO_EVENTS_PER_PAGE;
1249 :
1250 0 : avail = min(avail, nr - ret);
1251 0 : avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1252 :
1253 0 : ev = kmap(page);
1254 0 : copy_ret = copy_to_user(event + ret, ev + pos,
1255 : sizeof(*ev) * avail);
1256 0 : kunmap(page);
1257 :
1258 0 : if (unlikely(copy_ret)) {
1259 : ret = -EFAULT;
1260 : goto out;
1261 : }
1262 :
1263 0 : ret += avail;
1264 0 : head += avail;
1265 0 : head %= ctx->nr_events;
1266 : }
1267 :
1268 0 : ring = kmap_atomic(ctx->ring_pages[0]);
1269 0 : ring->head = head;
1270 0 : kunmap_atomic(ring);
1271 0 : flush_dcache_page(ctx->ring_pages[0]);
1272 :
1273 : pr_debug("%li h%u t%u\n", ret, head, tail);
1274 : out:
1275 0 : mutex_unlock(&ctx->ring_lock);
1276 :
1277 0 : return ret;
1278 : }
1279 :
1280 0 : static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1281 : struct io_event __user *event, long *i)
1282 : {
1283 0 : long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1284 :
1285 0 : if (ret > 0)
1286 0 : *i += ret;
1287 :
1288 0 : if (unlikely(atomic_read(&ctx->dead)))
1289 0 : ret = -EINVAL;
1290 :
1291 0 : if (!*i)
1292 0 : *i = ret;
1293 :
1294 0 : return ret < 0 || *i >= min_nr;
1295 : }
1296 :
1297 0 : static long read_events(struct kioctx *ctx, long min_nr, long nr,
1298 : struct io_event __user *event,
1299 : ktime_t until)
1300 : {
1301 0 : long ret = 0;
1302 :
1303 : /*
1304 : * Note that aio_read_events() is being called as the conditional - i.e.
1305 : * we're calling it after prepare_to_wait() has set task state to
1306 : * TASK_INTERRUPTIBLE.
1307 : *
1308 : * But aio_read_events() can block, and if it blocks it's going to flip
1309 : * the task state back to TASK_RUNNING.
1310 : *
1311 : * This should be ok, provided it doesn't flip the state back to
1312 : * TASK_RUNNING and return 0 too much - that causes us to spin. That
1313 : * will only happen if the mutex_lock() call blocks, and we then find
1314 : * the ringbuffer empty. So in practice we should be ok, but it's
1315 : * something to be aware of when touching this code.
1316 : */
1317 0 : if (until == 0)
1318 0 : aio_read_events(ctx, min_nr, nr, event, &ret);
1319 : else
1320 0 : wait_event_interruptible_hrtimeout(ctx->wait,
1321 : aio_read_events(ctx, min_nr, nr, event, &ret),
1322 : until);
1323 0 : return ret;
1324 : }
1325 :
1326 : /* sys_io_setup:
1327 : * Create an aio_context capable of receiving at least nr_events.
1328 : * ctxp must not point to an aio_context that already exists, and
1329 : * must be initialized to 0 prior to the call. On successful
1330 : * creation of the aio_context, *ctxp is filled in with the resulting
1331 : * handle. May fail with -EINVAL if *ctxp is not initialized,
1332 : * if the specified nr_events exceeds internal limits. May fail
1333 : * with -EAGAIN if the specified nr_events exceeds the user's limit
1334 : * of available events. May fail with -ENOMEM if insufficient kernel
1335 : * resources are available. May fail with -EFAULT if an invalid
1336 : * pointer is passed for ctxp. Will fail with -ENOSYS if not
1337 : * implemented.
1338 : */
1339 0 : SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1340 : {
1341 0 : struct kioctx *ioctx = NULL;
1342 : unsigned long ctx;
1343 : long ret;
1344 :
1345 0 : ret = get_user(ctx, ctxp);
1346 0 : if (unlikely(ret))
1347 : goto out;
1348 :
1349 0 : ret = -EINVAL;
1350 0 : if (unlikely(ctx || nr_events == 0)) {
1351 : pr_debug("EINVAL: ctx %lu nr_events %u\n",
1352 : ctx, nr_events);
1353 : goto out;
1354 : }
1355 :
1356 0 : ioctx = ioctx_alloc(nr_events);
1357 0 : ret = PTR_ERR(ioctx);
1358 0 : if (!IS_ERR(ioctx)) {
1359 0 : ret = put_user(ioctx->user_id, ctxp);
1360 0 : if (ret)
1361 0 : kill_ioctx(current->mm, ioctx, NULL);
1362 0 : percpu_ref_put(&ioctx->users);
1363 : }
1364 :
1365 : out:
1366 0 : return ret;
1367 : }
1368 :
1369 : #ifdef CONFIG_COMPAT
1370 : COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1371 : {
1372 : struct kioctx *ioctx = NULL;
1373 : unsigned long ctx;
1374 : long ret;
1375 :
1376 : ret = get_user(ctx, ctx32p);
1377 : if (unlikely(ret))
1378 : goto out;
1379 :
1380 : ret = -EINVAL;
1381 : if (unlikely(ctx || nr_events == 0)) {
1382 : pr_debug("EINVAL: ctx %lu nr_events %u\n",
1383 : ctx, nr_events);
1384 : goto out;
1385 : }
1386 :
1387 : ioctx = ioctx_alloc(nr_events);
1388 : ret = PTR_ERR(ioctx);
1389 : if (!IS_ERR(ioctx)) {
1390 : /* truncating is ok because it's a user address */
1391 : ret = put_user((u32)ioctx->user_id, ctx32p);
1392 : if (ret)
1393 : kill_ioctx(current->mm, ioctx, NULL);
1394 : percpu_ref_put(&ioctx->users);
1395 : }
1396 :
1397 : out:
1398 : return ret;
1399 : }
1400 : #endif
1401 :
1402 : /* sys_io_destroy:
1403 : * Destroy the aio_context specified. May cancel any outstanding
1404 : * AIOs and block on completion. Will fail with -ENOSYS if not
1405 : * implemented. May fail with -EINVAL if the context pointed to
1406 : * is invalid.
1407 : */
1408 0 : SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1409 : {
1410 0 : struct kioctx *ioctx = lookup_ioctx(ctx);
1411 0 : if (likely(NULL != ioctx)) {
1412 : struct ctx_rq_wait wait;
1413 : int ret;
1414 :
1415 0 : init_completion(&wait.comp);
1416 0 : atomic_set(&wait.count, 1);
1417 :
1418 : /* Pass requests_done to kill_ioctx() where it can be set
1419 : * in a thread-safe way. If we try to set it here then we have
1420 : * a race condition if two io_destroy() called simultaneously.
1421 : */
1422 0 : ret = kill_ioctx(current->mm, ioctx, &wait);
1423 0 : percpu_ref_put(&ioctx->users);
1424 :
1425 : /* Wait until all IO for the context are done. Otherwise kernel
1426 : * keep using user-space buffers even if user thinks the context
1427 : * is destroyed.
1428 : */
1429 0 : if (!ret)
1430 0 : wait_for_completion(&wait.comp);
1431 :
1432 0 : return ret;
1433 : }
1434 : pr_debug("EINVAL: invalid context id\n");
1435 : return -EINVAL;
1436 : }
1437 :
1438 0 : static void aio_remove_iocb(struct aio_kiocb *iocb)
1439 : {
1440 0 : struct kioctx *ctx = iocb->ki_ctx;
1441 : unsigned long flags;
1442 :
1443 0 : spin_lock_irqsave(&ctx->ctx_lock, flags);
1444 0 : list_del(&iocb->ki_list);
1445 0 : spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1446 0 : }
1447 :
1448 0 : static void aio_complete_rw(struct kiocb *kiocb, long res)
1449 : {
1450 0 : struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1451 :
1452 0 : if (!list_empty_careful(&iocb->ki_list))
1453 0 : aio_remove_iocb(iocb);
1454 :
1455 0 : if (kiocb->ki_flags & IOCB_WRITE) {
1456 0 : struct inode *inode = file_inode(kiocb->ki_filp);
1457 :
1458 : /*
1459 : * Tell lockdep we inherited freeze protection from submission
1460 : * thread.
1461 : */
1462 0 : if (S_ISREG(inode->i_mode))
1463 : __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
1464 0 : file_end_write(kiocb->ki_filp);
1465 : }
1466 :
1467 0 : iocb->ki_res.res = res;
1468 0 : iocb->ki_res.res2 = 0;
1469 0 : iocb_put(iocb);
1470 0 : }
1471 :
1472 0 : static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1473 : {
1474 : int ret;
1475 :
1476 0 : req->ki_complete = aio_complete_rw;
1477 0 : req->private = NULL;
1478 0 : req->ki_pos = iocb->aio_offset;
1479 0 : req->ki_flags = req->ki_filp->f_iocb_flags;
1480 0 : if (iocb->aio_flags & IOCB_FLAG_RESFD)
1481 0 : req->ki_flags |= IOCB_EVENTFD;
1482 0 : if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1483 : /*
1484 : * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1485 : * aio_reqprio is interpreted as an I/O scheduling
1486 : * class and priority.
1487 : */
1488 0 : ret = ioprio_check_cap(iocb->aio_reqprio);
1489 0 : if (ret) {
1490 : pr_debug("aio ioprio check cap error: %d\n", ret);
1491 : return ret;
1492 : }
1493 :
1494 0 : req->ki_ioprio = iocb->aio_reqprio;
1495 : } else
1496 0 : req->ki_ioprio = get_current_ioprio();
1497 :
1498 0 : ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
1499 0 : if (unlikely(ret))
1500 : return ret;
1501 :
1502 0 : req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1503 0 : return 0;
1504 : }
1505 :
1506 0 : static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1507 : struct iovec **iovec, bool vectored, bool compat,
1508 : struct iov_iter *iter)
1509 : {
1510 0 : void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1511 0 : size_t len = iocb->aio_nbytes;
1512 :
1513 0 : if (!vectored) {
1514 0 : ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
1515 0 : *iovec = NULL;
1516 0 : return ret;
1517 : }
1518 :
1519 0 : return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1520 : }
1521 :
1522 : static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1523 : {
1524 0 : switch (ret) {
1525 : case -EIOCBQUEUED:
1526 : break;
1527 : case -ERESTARTSYS:
1528 : case -ERESTARTNOINTR:
1529 : case -ERESTARTNOHAND:
1530 : case -ERESTART_RESTARTBLOCK:
1531 : /*
1532 : * There's no easy way to restart the syscall since other AIO's
1533 : * may be already running. Just fail this IO with EINTR.
1534 : */
1535 0 : ret = -EINTR;
1536 : fallthrough;
1537 : default:
1538 0 : req->ki_complete(req, ret);
1539 : }
1540 : }
1541 :
1542 0 : static int aio_read(struct kiocb *req, const struct iocb *iocb,
1543 : bool vectored, bool compat)
1544 : {
1545 0 : struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1546 : struct iov_iter iter;
1547 : struct file *file;
1548 : int ret;
1549 :
1550 0 : ret = aio_prep_rw(req, iocb);
1551 0 : if (ret)
1552 : return ret;
1553 0 : file = req->ki_filp;
1554 0 : if (unlikely(!(file->f_mode & FMODE_READ)))
1555 : return -EBADF;
1556 0 : if (unlikely(!file->f_op->read_iter))
1557 : return -EINVAL;
1558 :
1559 0 : ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
1560 0 : if (ret < 0)
1561 : return ret;
1562 0 : ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1563 0 : if (!ret)
1564 0 : aio_rw_done(req, call_read_iter(file, req, &iter));
1565 0 : kfree(iovec);
1566 0 : return ret;
1567 : }
1568 :
1569 0 : static int aio_write(struct kiocb *req, const struct iocb *iocb,
1570 : bool vectored, bool compat)
1571 : {
1572 0 : struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1573 : struct iov_iter iter;
1574 : struct file *file;
1575 : int ret;
1576 :
1577 0 : ret = aio_prep_rw(req, iocb);
1578 0 : if (ret)
1579 : return ret;
1580 0 : file = req->ki_filp;
1581 :
1582 0 : if (unlikely(!(file->f_mode & FMODE_WRITE)))
1583 : return -EBADF;
1584 0 : if (unlikely(!file->f_op->write_iter))
1585 : return -EINVAL;
1586 :
1587 0 : ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
1588 0 : if (ret < 0)
1589 : return ret;
1590 0 : ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1591 0 : if (!ret) {
1592 : /*
1593 : * Open-code file_start_write here to grab freeze protection,
1594 : * which will be released by another thread in
1595 : * aio_complete_rw(). Fool lockdep by telling it the lock got
1596 : * released so that it doesn't complain about the held lock when
1597 : * we return to userspace.
1598 : */
1599 0 : if (S_ISREG(file_inode(file)->i_mode)) {
1600 0 : sb_start_write(file_inode(file)->i_sb);
1601 : __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1602 : }
1603 0 : req->ki_flags |= IOCB_WRITE;
1604 0 : aio_rw_done(req, call_write_iter(file, req, &iter));
1605 : }
1606 0 : kfree(iovec);
1607 0 : return ret;
1608 : }
1609 :
1610 0 : static void aio_fsync_work(struct work_struct *work)
1611 : {
1612 0 : struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1613 0 : const struct cred *old_cred = override_creds(iocb->fsync.creds);
1614 :
1615 0 : iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1616 0 : revert_creds(old_cred);
1617 0 : put_cred(iocb->fsync.creds);
1618 0 : iocb_put(iocb);
1619 0 : }
1620 :
1621 0 : static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1622 : bool datasync)
1623 : {
1624 0 : if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1625 : iocb->aio_rw_flags))
1626 : return -EINVAL;
1627 :
1628 0 : if (unlikely(!req->file->f_op->fsync))
1629 : return -EINVAL;
1630 :
1631 0 : req->creds = prepare_creds();
1632 0 : if (!req->creds)
1633 : return -ENOMEM;
1634 :
1635 0 : req->datasync = datasync;
1636 0 : INIT_WORK(&req->work, aio_fsync_work);
1637 0 : schedule_work(&req->work);
1638 0 : return 0;
1639 : }
1640 :
1641 0 : static void aio_poll_put_work(struct work_struct *work)
1642 : {
1643 0 : struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1644 0 : struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1645 :
1646 0 : iocb_put(iocb);
1647 0 : }
1648 :
1649 : /*
1650 : * Safely lock the waitqueue which the request is on, synchronizing with the
1651 : * case where the ->poll() provider decides to free its waitqueue early.
1652 : *
1653 : * Returns true on success, meaning that req->head->lock was locked, req->wait
1654 : * is on req->head, and an RCU read lock was taken. Returns false if the
1655 : * request was already removed from its waitqueue (which might no longer exist).
1656 : */
1657 : static bool poll_iocb_lock_wq(struct poll_iocb *req)
1658 : {
1659 : wait_queue_head_t *head;
1660 :
1661 : /*
1662 : * While we hold the waitqueue lock and the waitqueue is nonempty,
1663 : * wake_up_pollfree() will wait for us. However, taking the waitqueue
1664 : * lock in the first place can race with the waitqueue being freed.
1665 : *
1666 : * We solve this as eventpoll does: by taking advantage of the fact that
1667 : * all users of wake_up_pollfree() will RCU-delay the actual free. If
1668 : * we enter rcu_read_lock() and see that the pointer to the queue is
1669 : * non-NULL, we can then lock it without the memory being freed out from
1670 : * under us, then check whether the request is still on the queue.
1671 : *
1672 : * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1673 : * case the caller deletes the entry from the queue, leaving it empty.
1674 : * In that case, only RCU prevents the queue memory from being freed.
1675 : */
1676 : rcu_read_lock();
1677 0 : head = smp_load_acquire(&req->head);
1678 0 : if (head) {
1679 0 : spin_lock(&head->lock);
1680 0 : if (!list_empty(&req->wait.entry))
1681 : return true;
1682 0 : spin_unlock(&head->lock);
1683 : }
1684 : rcu_read_unlock();
1685 : return false;
1686 : }
1687 :
1688 : static void poll_iocb_unlock_wq(struct poll_iocb *req)
1689 : {
1690 0 : spin_unlock(&req->head->lock);
1691 : rcu_read_unlock();
1692 : }
1693 :
1694 0 : static void aio_poll_complete_work(struct work_struct *work)
1695 : {
1696 0 : struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1697 0 : struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1698 0 : struct poll_table_struct pt = { ._key = req->events };
1699 0 : struct kioctx *ctx = iocb->ki_ctx;
1700 0 : __poll_t mask = 0;
1701 :
1702 0 : if (!READ_ONCE(req->cancelled))
1703 0 : mask = vfs_poll(req->file, &pt) & req->events;
1704 :
1705 : /*
1706 : * Note that ->ki_cancel callers also delete iocb from active_reqs after
1707 : * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1708 : * synchronize with them. In the cancellation case the list_del_init
1709 : * itself is not actually needed, but harmless so we keep it in to
1710 : * avoid further branches in the fast path.
1711 : */
1712 0 : spin_lock_irq(&ctx->ctx_lock);
1713 0 : if (poll_iocb_lock_wq(req)) {
1714 0 : if (!mask && !READ_ONCE(req->cancelled)) {
1715 : /*
1716 : * The request isn't actually ready to be completed yet.
1717 : * Reschedule completion if another wakeup came in.
1718 : */
1719 0 : if (req->work_need_resched) {
1720 0 : schedule_work(&req->work);
1721 0 : req->work_need_resched = false;
1722 : } else {
1723 0 : req->work_scheduled = false;
1724 : }
1725 0 : poll_iocb_unlock_wq(req);
1726 0 : spin_unlock_irq(&ctx->ctx_lock);
1727 0 : return;
1728 : }
1729 0 : list_del_init(&req->wait.entry);
1730 0 : poll_iocb_unlock_wq(req);
1731 : } /* else, POLLFREE has freed the waitqueue, so we must complete */
1732 0 : list_del_init(&iocb->ki_list);
1733 0 : iocb->ki_res.res = mangle_poll(mask);
1734 0 : spin_unlock_irq(&ctx->ctx_lock);
1735 :
1736 0 : iocb_put(iocb);
1737 : }
1738 :
1739 : /* assumes we are called with irqs disabled */
1740 0 : static int aio_poll_cancel(struct kiocb *iocb)
1741 : {
1742 0 : struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1743 0 : struct poll_iocb *req = &aiocb->poll;
1744 :
1745 0 : if (poll_iocb_lock_wq(req)) {
1746 0 : WRITE_ONCE(req->cancelled, true);
1747 0 : if (!req->work_scheduled) {
1748 0 : schedule_work(&aiocb->poll.work);
1749 0 : req->work_scheduled = true;
1750 : }
1751 0 : poll_iocb_unlock_wq(req);
1752 : } /* else, the request was force-cancelled by POLLFREE already */
1753 :
1754 0 : return 0;
1755 : }
1756 :
1757 0 : static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1758 : void *key)
1759 : {
1760 0 : struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1761 0 : struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1762 0 : __poll_t mask = key_to_poll(key);
1763 : unsigned long flags;
1764 :
1765 : /* for instances that support it check for an event match first: */
1766 0 : if (mask && !(mask & req->events))
1767 : return 0;
1768 :
1769 : /*
1770 : * Complete the request inline if possible. This requires that three
1771 : * conditions be met:
1772 : * 1. An event mask must have been passed. If a plain wakeup was done
1773 : * instead, then mask == 0 and we have to call vfs_poll() to get
1774 : * the events, so inline completion isn't possible.
1775 : * 2. The completion work must not have already been scheduled.
1776 : * 3. ctx_lock must not be busy. We have to use trylock because we
1777 : * already hold the waitqueue lock, so this inverts the normal
1778 : * locking order. Use irqsave/irqrestore because not all
1779 : * filesystems (e.g. fuse) call this function with IRQs disabled,
1780 : * yet IRQs have to be disabled before ctx_lock is obtained.
1781 : */
1782 0 : if (mask && !req->work_scheduled &&
1783 0 : spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1784 0 : struct kioctx *ctx = iocb->ki_ctx;
1785 :
1786 0 : list_del_init(&req->wait.entry);
1787 0 : list_del(&iocb->ki_list);
1788 0 : iocb->ki_res.res = mangle_poll(mask);
1789 0 : if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1790 0 : iocb = NULL;
1791 0 : INIT_WORK(&req->work, aio_poll_put_work);
1792 0 : schedule_work(&req->work);
1793 : }
1794 0 : spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1795 0 : if (iocb)
1796 0 : iocb_put(iocb);
1797 : } else {
1798 : /*
1799 : * Schedule the completion work if needed. If it was already
1800 : * scheduled, record that another wakeup came in.
1801 : *
1802 : * Don't remove the request from the waitqueue here, as it might
1803 : * not actually be complete yet (we won't know until vfs_poll()
1804 : * is called), and we must not miss any wakeups. POLLFREE is an
1805 : * exception to this; see below.
1806 : */
1807 0 : if (req->work_scheduled) {
1808 0 : req->work_need_resched = true;
1809 : } else {
1810 0 : schedule_work(&req->work);
1811 0 : req->work_scheduled = true;
1812 : }
1813 :
1814 : /*
1815 : * If the waitqueue is being freed early but we can't complete
1816 : * the request inline, we have to tear down the request as best
1817 : * we can. That means immediately removing the request from its
1818 : * waitqueue and preventing all further accesses to the
1819 : * waitqueue via the request. We also need to schedule the
1820 : * completion work (done above). Also mark the request as
1821 : * cancelled, to potentially skip an unneeded call to ->poll().
1822 : */
1823 0 : if (mask & POLLFREE) {
1824 0 : WRITE_ONCE(req->cancelled, true);
1825 0 : list_del_init(&req->wait.entry);
1826 :
1827 : /*
1828 : * Careful: this *must* be the last step, since as soon
1829 : * as req->head is NULL'ed out, the request can be
1830 : * completed and freed, since aio_poll_complete_work()
1831 : * will no longer need to take the waitqueue lock.
1832 : */
1833 0 : smp_store_release(&req->head, NULL);
1834 : }
1835 : }
1836 : return 1;
1837 : }
1838 :
1839 : struct aio_poll_table {
1840 : struct poll_table_struct pt;
1841 : struct aio_kiocb *iocb;
1842 : bool queued;
1843 : int error;
1844 : };
1845 :
1846 : static void
1847 0 : aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1848 : struct poll_table_struct *p)
1849 : {
1850 0 : struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1851 :
1852 : /* multiple wait queues per file are not supported */
1853 0 : if (unlikely(pt->queued)) {
1854 0 : pt->error = -EINVAL;
1855 0 : return;
1856 : }
1857 :
1858 0 : pt->queued = true;
1859 0 : pt->error = 0;
1860 0 : pt->iocb->poll.head = head;
1861 0 : add_wait_queue(head, &pt->iocb->poll.wait);
1862 : }
1863 :
1864 0 : static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1865 : {
1866 0 : struct kioctx *ctx = aiocb->ki_ctx;
1867 0 : struct poll_iocb *req = &aiocb->poll;
1868 : struct aio_poll_table apt;
1869 0 : bool cancel = false;
1870 : __poll_t mask;
1871 :
1872 : /* reject any unknown events outside the normal event mask. */
1873 0 : if ((u16)iocb->aio_buf != iocb->aio_buf)
1874 : return -EINVAL;
1875 : /* reject fields that are not defined for poll */
1876 0 : if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1877 : return -EINVAL;
1878 :
1879 0 : INIT_WORK(&req->work, aio_poll_complete_work);
1880 0 : req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1881 :
1882 0 : req->head = NULL;
1883 0 : req->cancelled = false;
1884 0 : req->work_scheduled = false;
1885 0 : req->work_need_resched = false;
1886 :
1887 0 : apt.pt._qproc = aio_poll_queue_proc;
1888 0 : apt.pt._key = req->events;
1889 0 : apt.iocb = aiocb;
1890 0 : apt.queued = false;
1891 0 : apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1892 :
1893 : /* initialized the list so that we can do list_empty checks */
1894 0 : INIT_LIST_HEAD(&req->wait.entry);
1895 0 : init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1896 :
1897 0 : mask = vfs_poll(req->file, &apt.pt) & req->events;
1898 0 : spin_lock_irq(&ctx->ctx_lock);
1899 0 : if (likely(apt.queued)) {
1900 0 : bool on_queue = poll_iocb_lock_wq(req);
1901 :
1902 0 : if (!on_queue || req->work_scheduled) {
1903 : /*
1904 : * aio_poll_wake() already either scheduled the async
1905 : * completion work, or completed the request inline.
1906 : */
1907 0 : if (apt.error) /* unsupported case: multiple queues */
1908 0 : cancel = true;
1909 0 : apt.error = 0;
1910 0 : mask = 0;
1911 : }
1912 0 : if (mask || apt.error) {
1913 : /* Steal to complete synchronously. */
1914 0 : list_del_init(&req->wait.entry);
1915 0 : } else if (cancel) {
1916 : /* Cancel if possible (may be too late though). */
1917 0 : WRITE_ONCE(req->cancelled, true);
1918 0 : } else if (on_queue) {
1919 : /*
1920 : * Actually waiting for an event, so add the request to
1921 : * active_reqs so that it can be cancelled if needed.
1922 : */
1923 0 : list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1924 0 : aiocb->ki_cancel = aio_poll_cancel;
1925 : }
1926 0 : if (on_queue)
1927 0 : poll_iocb_unlock_wq(req);
1928 : }
1929 0 : if (mask) { /* no async, we'd stolen it */
1930 0 : aiocb->ki_res.res = mangle_poll(mask);
1931 0 : apt.error = 0;
1932 : }
1933 0 : spin_unlock_irq(&ctx->ctx_lock);
1934 0 : if (mask)
1935 0 : iocb_put(aiocb);
1936 0 : return apt.error;
1937 : }
1938 :
1939 0 : static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1940 : struct iocb __user *user_iocb, struct aio_kiocb *req,
1941 : bool compat)
1942 : {
1943 0 : req->ki_filp = fget(iocb->aio_fildes);
1944 0 : if (unlikely(!req->ki_filp))
1945 : return -EBADF;
1946 :
1947 0 : if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1948 : struct eventfd_ctx *eventfd;
1949 : /*
1950 : * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1951 : * instance of the file* now. The file descriptor must be
1952 : * an eventfd() fd, and will be signaled for each completed
1953 : * event using the eventfd_signal() function.
1954 : */
1955 0 : eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1956 0 : if (IS_ERR(eventfd))
1957 0 : return PTR_ERR(eventfd);
1958 :
1959 0 : req->ki_eventfd = eventfd;
1960 : }
1961 :
1962 0 : if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1963 : pr_debug("EFAULT: aio_key\n");
1964 : return -EFAULT;
1965 : }
1966 :
1967 0 : req->ki_res.obj = (u64)(unsigned long)user_iocb;
1968 0 : req->ki_res.data = iocb->aio_data;
1969 0 : req->ki_res.res = 0;
1970 0 : req->ki_res.res2 = 0;
1971 :
1972 0 : switch (iocb->aio_lio_opcode) {
1973 : case IOCB_CMD_PREAD:
1974 0 : return aio_read(&req->rw, iocb, false, compat);
1975 : case IOCB_CMD_PWRITE:
1976 0 : return aio_write(&req->rw, iocb, false, compat);
1977 : case IOCB_CMD_PREADV:
1978 0 : return aio_read(&req->rw, iocb, true, compat);
1979 : case IOCB_CMD_PWRITEV:
1980 0 : return aio_write(&req->rw, iocb, true, compat);
1981 : case IOCB_CMD_FSYNC:
1982 0 : return aio_fsync(&req->fsync, iocb, false);
1983 : case IOCB_CMD_FDSYNC:
1984 0 : return aio_fsync(&req->fsync, iocb, true);
1985 : case IOCB_CMD_POLL:
1986 0 : return aio_poll(req, iocb);
1987 : default:
1988 : pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1989 : return -EINVAL;
1990 : }
1991 : }
1992 :
1993 0 : static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1994 : bool compat)
1995 : {
1996 : struct aio_kiocb *req;
1997 : struct iocb iocb;
1998 : int err;
1999 :
2000 0 : if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
2001 : return -EFAULT;
2002 :
2003 : /* enforce forwards compatibility on users */
2004 0 : if (unlikely(iocb.aio_reserved2)) {
2005 : pr_debug("EINVAL: reserve field set\n");
2006 : return -EINVAL;
2007 : }
2008 :
2009 : /* prevent overflows */
2010 0 : if (unlikely(
2011 : (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
2012 : (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
2013 : ((ssize_t)iocb.aio_nbytes < 0)
2014 : )) {
2015 : pr_debug("EINVAL: overflow check\n");
2016 : return -EINVAL;
2017 : }
2018 :
2019 0 : req = aio_get_req(ctx);
2020 0 : if (unlikely(!req))
2021 : return -EAGAIN;
2022 :
2023 0 : err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
2024 :
2025 : /* Done with the synchronous reference */
2026 0 : iocb_put(req);
2027 :
2028 : /*
2029 : * If err is 0, we'd either done aio_complete() ourselves or have
2030 : * arranged for that to be done asynchronously. Anything non-zero
2031 : * means that we need to destroy req ourselves.
2032 : */
2033 0 : if (unlikely(err)) {
2034 0 : iocb_destroy(req);
2035 0 : put_reqs_available(ctx, 1);
2036 : }
2037 : return err;
2038 : }
2039 :
2040 : /* sys_io_submit:
2041 : * Queue the nr iocbs pointed to by iocbpp for processing. Returns
2042 : * the number of iocbs queued. May return -EINVAL if the aio_context
2043 : * specified by ctx_id is invalid, if nr is < 0, if the iocb at
2044 : * *iocbpp[0] is not properly initialized, if the operation specified
2045 : * is invalid for the file descriptor in the iocb. May fail with
2046 : * -EFAULT if any of the data structures point to invalid data. May
2047 : * fail with -EBADF if the file descriptor specified in the first
2048 : * iocb is invalid. May fail with -EAGAIN if insufficient resources
2049 : * are available to queue any iocbs. Will return 0 if nr is 0. Will
2050 : * fail with -ENOSYS if not implemented.
2051 : */
2052 0 : SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2053 : struct iocb __user * __user *, iocbpp)
2054 : {
2055 : struct kioctx *ctx;
2056 0 : long ret = 0;
2057 0 : int i = 0;
2058 : struct blk_plug plug;
2059 :
2060 0 : if (unlikely(nr < 0))
2061 : return -EINVAL;
2062 :
2063 0 : ctx = lookup_ioctx(ctx_id);
2064 0 : if (unlikely(!ctx)) {
2065 : pr_debug("EINVAL: invalid context id\n");
2066 : return -EINVAL;
2067 : }
2068 :
2069 0 : if (nr > ctx->nr_events)
2070 0 : nr = ctx->nr_events;
2071 :
2072 0 : if (nr > AIO_PLUG_THRESHOLD)
2073 0 : blk_start_plug(&plug);
2074 0 : for (i = 0; i < nr; i++) {
2075 : struct iocb __user *user_iocb;
2076 :
2077 0 : if (unlikely(get_user(user_iocb, iocbpp + i))) {
2078 : ret = -EFAULT;
2079 : break;
2080 : }
2081 :
2082 0 : ret = io_submit_one(ctx, user_iocb, false);
2083 0 : if (ret)
2084 : break;
2085 : }
2086 0 : if (nr > AIO_PLUG_THRESHOLD)
2087 0 : blk_finish_plug(&plug);
2088 :
2089 0 : percpu_ref_put(&ctx->users);
2090 0 : return i ? i : ret;
2091 : }
2092 :
2093 : #ifdef CONFIG_COMPAT
2094 : COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2095 : int, nr, compat_uptr_t __user *, iocbpp)
2096 : {
2097 : struct kioctx *ctx;
2098 : long ret = 0;
2099 : int i = 0;
2100 : struct blk_plug plug;
2101 :
2102 : if (unlikely(nr < 0))
2103 : return -EINVAL;
2104 :
2105 : ctx = lookup_ioctx(ctx_id);
2106 : if (unlikely(!ctx)) {
2107 : pr_debug("EINVAL: invalid context id\n");
2108 : return -EINVAL;
2109 : }
2110 :
2111 : if (nr > ctx->nr_events)
2112 : nr = ctx->nr_events;
2113 :
2114 : if (nr > AIO_PLUG_THRESHOLD)
2115 : blk_start_plug(&plug);
2116 : for (i = 0; i < nr; i++) {
2117 : compat_uptr_t user_iocb;
2118 :
2119 : if (unlikely(get_user(user_iocb, iocbpp + i))) {
2120 : ret = -EFAULT;
2121 : break;
2122 : }
2123 :
2124 : ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2125 : if (ret)
2126 : break;
2127 : }
2128 : if (nr > AIO_PLUG_THRESHOLD)
2129 : blk_finish_plug(&plug);
2130 :
2131 : percpu_ref_put(&ctx->users);
2132 : return i ? i : ret;
2133 : }
2134 : #endif
2135 :
2136 : /* sys_io_cancel:
2137 : * Attempts to cancel an iocb previously passed to io_submit. If
2138 : * the operation is successfully cancelled, the resulting event is
2139 : * copied into the memory pointed to by result without being placed
2140 : * into the completion queue and 0 is returned. May fail with
2141 : * -EFAULT if any of the data structures pointed to are invalid.
2142 : * May fail with -EINVAL if aio_context specified by ctx_id is
2143 : * invalid. May fail with -EAGAIN if the iocb specified was not
2144 : * cancelled. Will fail with -ENOSYS if not implemented.
2145 : */
2146 0 : SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2147 : struct io_event __user *, result)
2148 : {
2149 : struct kioctx *ctx;
2150 : struct aio_kiocb *kiocb;
2151 0 : int ret = -EINVAL;
2152 : u32 key;
2153 0 : u64 obj = (u64)(unsigned long)iocb;
2154 :
2155 0 : if (unlikely(get_user(key, &iocb->aio_key)))
2156 : return -EFAULT;
2157 0 : if (unlikely(key != KIOCB_KEY))
2158 : return -EINVAL;
2159 :
2160 0 : ctx = lookup_ioctx(ctx_id);
2161 0 : if (unlikely(!ctx))
2162 : return -EINVAL;
2163 :
2164 0 : spin_lock_irq(&ctx->ctx_lock);
2165 : /* TODO: use a hash or array, this sucks. */
2166 0 : list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2167 0 : if (kiocb->ki_res.obj == obj) {
2168 0 : ret = kiocb->ki_cancel(&kiocb->rw);
2169 0 : list_del_init(&kiocb->ki_list);
2170 : break;
2171 : }
2172 : }
2173 0 : spin_unlock_irq(&ctx->ctx_lock);
2174 :
2175 0 : if (!ret) {
2176 : /*
2177 : * The result argument is no longer used - the io_event is
2178 : * always delivered via the ring buffer. -EINPROGRESS indicates
2179 : * cancellation is progress:
2180 : */
2181 0 : ret = -EINPROGRESS;
2182 : }
2183 :
2184 0 : percpu_ref_put(&ctx->users);
2185 :
2186 0 : return ret;
2187 : }
2188 :
2189 0 : static long do_io_getevents(aio_context_t ctx_id,
2190 : long min_nr,
2191 : long nr,
2192 : struct io_event __user *events,
2193 : struct timespec64 *ts)
2194 : {
2195 0 : ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2196 0 : struct kioctx *ioctx = lookup_ioctx(ctx_id);
2197 0 : long ret = -EINVAL;
2198 :
2199 0 : if (likely(ioctx)) {
2200 0 : if (likely(min_nr <= nr && min_nr >= 0))
2201 0 : ret = read_events(ioctx, min_nr, nr, events, until);
2202 0 : percpu_ref_put(&ioctx->users);
2203 : }
2204 :
2205 0 : return ret;
2206 : }
2207 :
2208 : /* io_getevents:
2209 : * Attempts to read at least min_nr events and up to nr events from
2210 : * the completion queue for the aio_context specified by ctx_id. If
2211 : * it succeeds, the number of read events is returned. May fail with
2212 : * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2213 : * out of range, if timeout is out of range. May fail with -EFAULT
2214 : * if any of the memory specified is invalid. May return 0 or
2215 : * < min_nr if the timeout specified by timeout has elapsed
2216 : * before sufficient events are available, where timeout == NULL
2217 : * specifies an infinite timeout. Note that the timeout pointed to by
2218 : * timeout is relative. Will fail with -ENOSYS if not implemented.
2219 : */
2220 : #ifdef CONFIG_64BIT
2221 :
2222 0 : SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2223 : long, min_nr,
2224 : long, nr,
2225 : struct io_event __user *, events,
2226 : struct __kernel_timespec __user *, timeout)
2227 : {
2228 : struct timespec64 ts;
2229 : int ret;
2230 :
2231 0 : if (timeout && unlikely(get_timespec64(&ts, timeout)))
2232 : return -EFAULT;
2233 :
2234 0 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2235 0 : if (!ret && signal_pending(current))
2236 0 : ret = -EINTR;
2237 0 : return ret;
2238 : }
2239 :
2240 : #endif
2241 :
2242 : struct __aio_sigset {
2243 : const sigset_t __user *sigmask;
2244 : size_t sigsetsize;
2245 : };
2246 :
2247 0 : SYSCALL_DEFINE6(io_pgetevents,
2248 : aio_context_t, ctx_id,
2249 : long, min_nr,
2250 : long, nr,
2251 : struct io_event __user *, events,
2252 : struct __kernel_timespec __user *, timeout,
2253 : const struct __aio_sigset __user *, usig)
2254 : {
2255 0 : struct __aio_sigset ksig = { NULL, };
2256 : struct timespec64 ts;
2257 : bool interrupted;
2258 : int ret;
2259 :
2260 0 : if (timeout && unlikely(get_timespec64(&ts, timeout)))
2261 : return -EFAULT;
2262 :
2263 0 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2264 : return -EFAULT;
2265 :
2266 0 : ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2267 0 : if (ret)
2268 0 : return ret;
2269 :
2270 0 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2271 :
2272 0 : interrupted = signal_pending(current);
2273 0 : restore_saved_sigmask_unless(interrupted);
2274 0 : if (interrupted && !ret)
2275 0 : ret = -ERESTARTNOHAND;
2276 :
2277 0 : return ret;
2278 : }
2279 :
2280 : #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2281 :
2282 : SYSCALL_DEFINE6(io_pgetevents_time32,
2283 : aio_context_t, ctx_id,
2284 : long, min_nr,
2285 : long, nr,
2286 : struct io_event __user *, events,
2287 : struct old_timespec32 __user *, timeout,
2288 : const struct __aio_sigset __user *, usig)
2289 : {
2290 : struct __aio_sigset ksig = { NULL, };
2291 : struct timespec64 ts;
2292 : bool interrupted;
2293 : int ret;
2294 :
2295 : if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2296 : return -EFAULT;
2297 :
2298 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2299 : return -EFAULT;
2300 :
2301 :
2302 : ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2303 : if (ret)
2304 : return ret;
2305 :
2306 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2307 :
2308 : interrupted = signal_pending(current);
2309 : restore_saved_sigmask_unless(interrupted);
2310 : if (interrupted && !ret)
2311 : ret = -ERESTARTNOHAND;
2312 :
2313 : return ret;
2314 : }
2315 :
2316 : #endif
2317 :
2318 : #if defined(CONFIG_COMPAT_32BIT_TIME)
2319 :
2320 : SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2321 : __s32, min_nr,
2322 : __s32, nr,
2323 : struct io_event __user *, events,
2324 : struct old_timespec32 __user *, timeout)
2325 : {
2326 : struct timespec64 t;
2327 : int ret;
2328 :
2329 : if (timeout && get_old_timespec32(&t, timeout))
2330 : return -EFAULT;
2331 :
2332 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2333 : if (!ret && signal_pending(current))
2334 : ret = -EINTR;
2335 : return ret;
2336 : }
2337 :
2338 : #endif
2339 :
2340 : #ifdef CONFIG_COMPAT
2341 :
2342 : struct __compat_aio_sigset {
2343 : compat_uptr_t sigmask;
2344 : compat_size_t sigsetsize;
2345 : };
2346 :
2347 : #if defined(CONFIG_COMPAT_32BIT_TIME)
2348 :
2349 : COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2350 : compat_aio_context_t, ctx_id,
2351 : compat_long_t, min_nr,
2352 : compat_long_t, nr,
2353 : struct io_event __user *, events,
2354 : struct old_timespec32 __user *, timeout,
2355 : const struct __compat_aio_sigset __user *, usig)
2356 : {
2357 : struct __compat_aio_sigset ksig = { 0, };
2358 : struct timespec64 t;
2359 : bool interrupted;
2360 : int ret;
2361 :
2362 : if (timeout && get_old_timespec32(&t, timeout))
2363 : return -EFAULT;
2364 :
2365 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2366 : return -EFAULT;
2367 :
2368 : ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2369 : if (ret)
2370 : return ret;
2371 :
2372 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2373 :
2374 : interrupted = signal_pending(current);
2375 : restore_saved_sigmask_unless(interrupted);
2376 : if (interrupted && !ret)
2377 : ret = -ERESTARTNOHAND;
2378 :
2379 : return ret;
2380 : }
2381 :
2382 : #endif
2383 :
2384 : COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2385 : compat_aio_context_t, ctx_id,
2386 : compat_long_t, min_nr,
2387 : compat_long_t, nr,
2388 : struct io_event __user *, events,
2389 : struct __kernel_timespec __user *, timeout,
2390 : const struct __compat_aio_sigset __user *, usig)
2391 : {
2392 : struct __compat_aio_sigset ksig = { 0, };
2393 : struct timespec64 t;
2394 : bool interrupted;
2395 : int ret;
2396 :
2397 : if (timeout && get_timespec64(&t, timeout))
2398 : return -EFAULT;
2399 :
2400 : if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2401 : return -EFAULT;
2402 :
2403 : ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2404 : if (ret)
2405 : return ret;
2406 :
2407 : ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2408 :
2409 : interrupted = signal_pending(current);
2410 : restore_saved_sigmask_unless(interrupted);
2411 : if (interrupted && !ret)
2412 : ret = -ERESTARTNOHAND;
2413 :
2414 : return ret;
2415 : }
2416 : #endif
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