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