Version:  2.0.40 2.2.26 2.4.37 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17

Linux/fs/aio.c

  1 /*
  2  *      An async IO implementation for Linux
  3  *      Written by Benjamin LaHaise <bcrl@kvack.org>
  4  *
  5  *      Implements an efficient asynchronous io interface.
  6  *
  7  *      Copyright 2000, 2001, 2002 Red Hat, Inc.  All Rights Reserved.
  8  *
  9  *      See ../COPYING for licensing terms.
 10  */
 11 #define pr_fmt(fmt) "%s: " fmt, __func__
 12 
 13 #include <linux/kernel.h>
 14 #include <linux/init.h>
 15 #include <linux/errno.h>
 16 #include <linux/time.h>
 17 #include <linux/aio_abi.h>
 18 #include <linux/export.h>
 19 #include <linux/syscalls.h>
 20 #include <linux/backing-dev.h>
 21 #include <linux/uio.h>
 22 
 23 #include <linux/sched.h>
 24 #include <linux/fs.h>
 25 #include <linux/file.h>
 26 #include <linux/mm.h>
 27 #include <linux/mman.h>
 28 #include <linux/mmu_context.h>
 29 #include <linux/percpu.h>
 30 #include <linux/slab.h>
 31 #include <linux/timer.h>
 32 #include <linux/aio.h>
 33 #include <linux/highmem.h>
 34 #include <linux/workqueue.h>
 35 #include <linux/security.h>
 36 #include <linux/eventfd.h>
 37 #include <linux/blkdev.h>
 38 #include <linux/compat.h>
 39 #include <linux/migrate.h>
 40 #include <linux/ramfs.h>
 41 #include <linux/percpu-refcount.h>
 42 #include <linux/mount.h>
 43 
 44 #include <asm/kmap_types.h>
 45 #include <asm/uaccess.h>
 46 
 47 #include "internal.h"
 48 
 49 #define AIO_RING_MAGIC                  0xa10a10a1
 50 #define AIO_RING_COMPAT_FEATURES        1
 51 #define AIO_RING_INCOMPAT_FEATURES      0
 52 struct aio_ring {
 53         unsigned        id;     /* kernel internal index number */
 54         unsigned        nr;     /* number of io_events */
 55         unsigned        head;   /* Written to by userland or under ring_lock
 56                                  * mutex by aio_read_events_ring(). */
 57         unsigned        tail;
 58 
 59         unsigned        magic;
 60         unsigned        compat_features;
 61         unsigned        incompat_features;
 62         unsigned        header_length;  /* size of aio_ring */
 63 
 64 
 65         struct io_event         io_events[0];
 66 }; /* 128 bytes + ring size */
 67 
 68 #define AIO_RING_PAGES  8
 69 
 70 struct kioctx_table {
 71         struct rcu_head rcu;
 72         unsigned        nr;
 73         struct kioctx   *table[];
 74 };
 75 
 76 struct kioctx_cpu {
 77         unsigned                reqs_available;
 78 };
 79 
 80 struct kioctx {
 81         struct percpu_ref       users;
 82         atomic_t                dead;
 83 
 84         struct percpu_ref       reqs;
 85 
 86         unsigned long           user_id;
 87 
 88         struct __percpu kioctx_cpu *cpu;
 89 
 90         /*
 91          * For percpu reqs_available, number of slots we move to/from global
 92          * counter at a time:
 93          */
 94         unsigned                req_batch;
 95         /*
 96          * This is what userspace passed to io_setup(), it's not used for
 97          * anything but counting against the global max_reqs quota.
 98          *
 99          * The real limit is nr_events - 1, which will be larger (see
100          * aio_setup_ring())
101          */
102         unsigned                max_reqs;
103 
104         /* Size of ringbuffer, in units of struct io_event */
105         unsigned                nr_events;
106 
107         unsigned long           mmap_base;
108         unsigned long           mmap_size;
109 
110         struct page             **ring_pages;
111         long                    nr_pages;
112 
113         struct work_struct      free_work;
114 
115         /*
116          * signals when all in-flight requests are done
117          */
118         struct completion *requests_done;
119 
120         struct {
121                 /*
122                  * This counts the number of available slots in the ringbuffer,
123                  * so we avoid overflowing it: it's decremented (if positive)
124                  * when allocating a kiocb and incremented when the resulting
125                  * io_event is pulled off the ringbuffer.
126                  *
127                  * We batch accesses to it with a percpu version.
128                  */
129                 atomic_t        reqs_available;
130         } ____cacheline_aligned_in_smp;
131 
132         struct {
133                 spinlock_t      ctx_lock;
134                 struct list_head active_reqs;   /* used for cancellation */
135         } ____cacheline_aligned_in_smp;
136 
137         struct {
138                 struct mutex    ring_lock;
139                 wait_queue_head_t wait;
140         } ____cacheline_aligned_in_smp;
141 
142         struct {
143                 unsigned        tail;
144                 unsigned        completed_events;
145                 spinlock_t      completion_lock;
146         } ____cacheline_aligned_in_smp;
147 
148         struct page             *internal_pages[AIO_RING_PAGES];
149         struct file             *aio_ring_file;
150 
151         unsigned                id;
152 };
153 
154 /*------ sysctl variables----*/
155 static DEFINE_SPINLOCK(aio_nr_lock);
156 unsigned long aio_nr;           /* current system wide number of aio requests */
157 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
158 /*----end sysctl variables---*/
159 
160 static struct kmem_cache        *kiocb_cachep;
161 static struct kmem_cache        *kioctx_cachep;
162 
163 static struct vfsmount *aio_mnt;
164 
165 static const struct file_operations aio_ring_fops;
166 static const struct address_space_operations aio_ctx_aops;
167 
168 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
169 {
170         struct qstr this = QSTR_INIT("[aio]", 5);
171         struct file *file;
172         struct path path;
173         struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
174         if (IS_ERR(inode))
175                 return ERR_CAST(inode);
176 
177         inode->i_mapping->a_ops = &aio_ctx_aops;
178         inode->i_mapping->private_data = ctx;
179         inode->i_size = PAGE_SIZE * nr_pages;
180 
181         path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
182         if (!path.dentry) {
183                 iput(inode);
184                 return ERR_PTR(-ENOMEM);
185         }
186         path.mnt = mntget(aio_mnt);
187 
188         d_instantiate(path.dentry, inode);
189         file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
190         if (IS_ERR(file)) {
191                 path_put(&path);
192                 return file;
193         }
194 
195         file->f_flags = O_RDWR;
196         return file;
197 }
198 
199 static struct dentry *aio_mount(struct file_system_type *fs_type,
200                                 int flags, const char *dev_name, void *data)
201 {
202         static const struct dentry_operations ops = {
203                 .d_dname        = simple_dname,
204         };
205         return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
206 }
207 
208 /* aio_setup
209  *      Creates the slab caches used by the aio routines, panic on
210  *      failure as this is done early during the boot sequence.
211  */
212 static int __init aio_setup(void)
213 {
214         static struct file_system_type aio_fs = {
215                 .name           = "aio",
216                 .mount          = aio_mount,
217                 .kill_sb        = kill_anon_super,
218         };
219         aio_mnt = kern_mount(&aio_fs);
220         if (IS_ERR(aio_mnt))
221                 panic("Failed to create aio fs mount.");
222 
223         kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
224         kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
225 
226         pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
227 
228         return 0;
229 }
230 __initcall(aio_setup);
231 
232 static void put_aio_ring_file(struct kioctx *ctx)
233 {
234         struct file *aio_ring_file = ctx->aio_ring_file;
235         if (aio_ring_file) {
236                 truncate_setsize(aio_ring_file->f_inode, 0);
237 
238                 /* Prevent further access to the kioctx from migratepages */
239                 spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
240                 aio_ring_file->f_inode->i_mapping->private_data = NULL;
241                 ctx->aio_ring_file = NULL;
242                 spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
243 
244                 fput(aio_ring_file);
245         }
246 }
247 
248 static void aio_free_ring(struct kioctx *ctx)
249 {
250         int i;
251 
252         /* Disconnect the kiotx from the ring file.  This prevents future
253          * accesses to the kioctx from page migration.
254          */
255         put_aio_ring_file(ctx);
256 
257         for (i = 0; i < ctx->nr_pages; i++) {
258                 struct page *page;
259                 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
260                                 page_count(ctx->ring_pages[i]));
261                 page = ctx->ring_pages[i];
262                 if (!page)
263                         continue;
264                 ctx->ring_pages[i] = NULL;
265                 put_page(page);
266         }
267 
268         if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
269                 kfree(ctx->ring_pages);
270                 ctx->ring_pages = NULL;
271         }
272 }
273 
274 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
275 {
276         vma->vm_ops = &generic_file_vm_ops;
277         return 0;
278 }
279 
280 static const struct file_operations aio_ring_fops = {
281         .mmap = aio_ring_mmap,
282 };
283 
284 static int aio_set_page_dirty(struct page *page)
285 {
286         return 0;
287 }
288 
289 #if IS_ENABLED(CONFIG_MIGRATION)
290 static int aio_migratepage(struct address_space *mapping, struct page *new,
291                         struct page *old, enum migrate_mode mode)
292 {
293         struct kioctx *ctx;
294         unsigned long flags;
295         pgoff_t idx;
296         int rc;
297 
298         rc = 0;
299 
300         /* mapping->private_lock here protects against the kioctx teardown.  */
301         spin_lock(&mapping->private_lock);
302         ctx = mapping->private_data;
303         if (!ctx) {
304                 rc = -EINVAL;
305                 goto out;
306         }
307 
308         /* The ring_lock mutex.  The prevents aio_read_events() from writing
309          * to the ring's head, and prevents page migration from mucking in
310          * a partially initialized kiotx.
311          */
312         if (!mutex_trylock(&ctx->ring_lock)) {
313                 rc = -EAGAIN;
314                 goto out;
315         }
316 
317         idx = old->index;
318         if (idx < (pgoff_t)ctx->nr_pages) {
319                 /* Make sure the old page hasn't already been changed */
320                 if (ctx->ring_pages[idx] != old)
321                         rc = -EAGAIN;
322         } else
323                 rc = -EINVAL;
324 
325         if (rc != 0)
326                 goto out_unlock;
327 
328         /* Writeback must be complete */
329         BUG_ON(PageWriteback(old));
330         get_page(new);
331 
332         rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
333         if (rc != MIGRATEPAGE_SUCCESS) {
334                 put_page(new);
335                 goto out_unlock;
336         }
337 
338         /* Take completion_lock to prevent other writes to the ring buffer
339          * while the old page is copied to the new.  This prevents new
340          * events from being lost.
341          */
342         spin_lock_irqsave(&ctx->completion_lock, flags);
343         migrate_page_copy(new, old);
344         BUG_ON(ctx->ring_pages[idx] != old);
345         ctx->ring_pages[idx] = new;
346         spin_unlock_irqrestore(&ctx->completion_lock, flags);
347 
348         /* The old page is no longer accessible. */
349         put_page(old);
350 
351 out_unlock:
352         mutex_unlock(&ctx->ring_lock);
353 out:
354         spin_unlock(&mapping->private_lock);
355         return rc;
356 }
357 #endif
358 
359 static const struct address_space_operations aio_ctx_aops = {
360         .set_page_dirty = aio_set_page_dirty,
361 #if IS_ENABLED(CONFIG_MIGRATION)
362         .migratepage    = aio_migratepage,
363 #endif
364 };
365 
366 static int aio_setup_ring(struct kioctx *ctx)
367 {
368         struct aio_ring *ring;
369         unsigned nr_events = ctx->max_reqs;
370         struct mm_struct *mm = current->mm;
371         unsigned long size, unused;
372         int nr_pages;
373         int i;
374         struct file *file;
375 
376         /* Compensate for the ring buffer's head/tail overlap entry */
377         nr_events += 2; /* 1 is required, 2 for good luck */
378 
379         size = sizeof(struct aio_ring);
380         size += sizeof(struct io_event) * nr_events;
381 
382         nr_pages = PFN_UP(size);
383         if (nr_pages < 0)
384                 return -EINVAL;
385 
386         file = aio_private_file(ctx, nr_pages);
387         if (IS_ERR(file)) {
388                 ctx->aio_ring_file = NULL;
389                 return -ENOMEM;
390         }
391 
392         ctx->aio_ring_file = file;
393         nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
394                         / sizeof(struct io_event);
395 
396         ctx->ring_pages = ctx->internal_pages;
397         if (nr_pages > AIO_RING_PAGES) {
398                 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
399                                           GFP_KERNEL);
400                 if (!ctx->ring_pages) {
401                         put_aio_ring_file(ctx);
402                         return -ENOMEM;
403                 }
404         }
405 
406         for (i = 0; i < nr_pages; i++) {
407                 struct page *page;
408                 page = find_or_create_page(file->f_inode->i_mapping,
409                                            i, GFP_HIGHUSER | __GFP_ZERO);
410                 if (!page)
411                         break;
412                 pr_debug("pid(%d) page[%d]->count=%d\n",
413                          current->pid, i, page_count(page));
414                 SetPageUptodate(page);
415                 SetPageDirty(page);
416                 unlock_page(page);
417 
418                 ctx->ring_pages[i] = page;
419         }
420         ctx->nr_pages = i;
421 
422         if (unlikely(i != nr_pages)) {
423                 aio_free_ring(ctx);
424                 return -ENOMEM;
425         }
426 
427         ctx->mmap_size = nr_pages * PAGE_SIZE;
428         pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
429 
430         down_write(&mm->mmap_sem);
431         ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
432                                        PROT_READ | PROT_WRITE,
433                                        MAP_SHARED, 0, &unused);
434         up_write(&mm->mmap_sem);
435         if (IS_ERR((void *)ctx->mmap_base)) {
436                 ctx->mmap_size = 0;
437                 aio_free_ring(ctx);
438                 return -ENOMEM;
439         }
440 
441         pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
442 
443         ctx->user_id = ctx->mmap_base;
444         ctx->nr_events = nr_events; /* trusted copy */
445 
446         ring = kmap_atomic(ctx->ring_pages[0]);
447         ring->nr = nr_events;   /* user copy */
448         ring->id = ~0U;
449         ring->head = ring->tail = 0;
450         ring->magic = AIO_RING_MAGIC;
451         ring->compat_features = AIO_RING_COMPAT_FEATURES;
452         ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
453         ring->header_length = sizeof(struct aio_ring);
454         kunmap_atomic(ring);
455         flush_dcache_page(ctx->ring_pages[0]);
456 
457         return 0;
458 }
459 
460 #define AIO_EVENTS_PER_PAGE     (PAGE_SIZE / sizeof(struct io_event))
461 #define AIO_EVENTS_FIRST_PAGE   ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
462 #define AIO_EVENTS_OFFSET       (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
463 
464 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
465 {
466         struct kioctx *ctx = req->ki_ctx;
467         unsigned long flags;
468 
469         spin_lock_irqsave(&ctx->ctx_lock, flags);
470 
471         if (!req->ki_list.next)
472                 list_add(&req->ki_list, &ctx->active_reqs);
473 
474         req->ki_cancel = cancel;
475 
476         spin_unlock_irqrestore(&ctx->ctx_lock, flags);
477 }
478 EXPORT_SYMBOL(kiocb_set_cancel_fn);
479 
480 static int kiocb_cancel(struct kiocb *kiocb)
481 {
482         kiocb_cancel_fn *old, *cancel;
483 
484         /*
485          * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
486          * actually has a cancel function, hence the cmpxchg()
487          */
488 
489         cancel = ACCESS_ONCE(kiocb->ki_cancel);
490         do {
491                 if (!cancel || cancel == KIOCB_CANCELLED)
492                         return -EINVAL;
493 
494                 old = cancel;
495                 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
496         } while (cancel != old);
497 
498         return cancel(kiocb);
499 }
500 
501 static void free_ioctx(struct work_struct *work)
502 {
503         struct kioctx *ctx = container_of(work, struct kioctx, free_work);
504 
505         pr_debug("freeing %p\n", ctx);
506 
507         aio_free_ring(ctx);
508         free_percpu(ctx->cpu);
509         percpu_ref_exit(&ctx->reqs);
510         percpu_ref_exit(&ctx->users);
511         kmem_cache_free(kioctx_cachep, ctx);
512 }
513 
514 static void free_ioctx_reqs(struct percpu_ref *ref)
515 {
516         struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
517 
518         /* At this point we know that there are no any in-flight requests */
519         if (ctx->requests_done)
520                 complete(ctx->requests_done);
521 
522         INIT_WORK(&ctx->free_work, free_ioctx);
523         schedule_work(&ctx->free_work);
524 }
525 
526 /*
527  * When this function runs, the kioctx has been removed from the "hash table"
528  * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
529  * now it's safe to cancel any that need to be.
530  */
531 static void free_ioctx_users(struct percpu_ref *ref)
532 {
533         struct kioctx *ctx = container_of(ref, struct kioctx, users);
534         struct kiocb *req;
535 
536         spin_lock_irq(&ctx->ctx_lock);
537 
538         while (!list_empty(&ctx->active_reqs)) {
539                 req = list_first_entry(&ctx->active_reqs,
540                                        struct kiocb, ki_list);
541 
542                 list_del_init(&req->ki_list);
543                 kiocb_cancel(req);
544         }
545 
546         spin_unlock_irq(&ctx->ctx_lock);
547 
548         percpu_ref_kill(&ctx->reqs);
549         percpu_ref_put(&ctx->reqs);
550 }
551 
552 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
553 {
554         unsigned i, new_nr;
555         struct kioctx_table *table, *old;
556         struct aio_ring *ring;
557 
558         spin_lock(&mm->ioctx_lock);
559         table = rcu_dereference_raw(mm->ioctx_table);
560 
561         while (1) {
562                 if (table)
563                         for (i = 0; i < table->nr; i++)
564                                 if (!table->table[i]) {
565                                         ctx->id = i;
566                                         table->table[i] = ctx;
567                                         spin_unlock(&mm->ioctx_lock);
568 
569                                         /* While kioctx setup is in progress,
570                                          * we are protected from page migration
571                                          * changes ring_pages by ->ring_lock.
572                                          */
573                                         ring = kmap_atomic(ctx->ring_pages[0]);
574                                         ring->id = ctx->id;
575                                         kunmap_atomic(ring);
576                                         return 0;
577                                 }
578 
579                 new_nr = (table ? table->nr : 1) * 4;
580                 spin_unlock(&mm->ioctx_lock);
581 
582                 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
583                                 new_nr, GFP_KERNEL);
584                 if (!table)
585                         return -ENOMEM;
586 
587                 table->nr = new_nr;
588 
589                 spin_lock(&mm->ioctx_lock);
590                 old = rcu_dereference_raw(mm->ioctx_table);
591 
592                 if (!old) {
593                         rcu_assign_pointer(mm->ioctx_table, table);
594                 } else if (table->nr > old->nr) {
595                         memcpy(table->table, old->table,
596                                old->nr * sizeof(struct kioctx *));
597 
598                         rcu_assign_pointer(mm->ioctx_table, table);
599                         kfree_rcu(old, rcu);
600                 } else {
601                         kfree(table);
602                         table = old;
603                 }
604         }
605 }
606 
607 static void aio_nr_sub(unsigned nr)
608 {
609         spin_lock(&aio_nr_lock);
610         if (WARN_ON(aio_nr - nr > aio_nr))
611                 aio_nr = 0;
612         else
613                 aio_nr -= nr;
614         spin_unlock(&aio_nr_lock);
615 }
616 
617 /* ioctx_alloc
618  *      Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
619  */
620 static struct kioctx *ioctx_alloc(unsigned nr_events)
621 {
622         struct mm_struct *mm = current->mm;
623         struct kioctx *ctx;
624         int err = -ENOMEM;
625 
626         /*
627          * We keep track of the number of available ringbuffer slots, to prevent
628          * overflow (reqs_available), and we also use percpu counters for this.
629          *
630          * So since up to half the slots might be on other cpu's percpu counters
631          * and unavailable, double nr_events so userspace sees what they
632          * expected: additionally, we move req_batch slots to/from percpu
633          * counters at a time, so make sure that isn't 0:
634          */
635         nr_events = max(nr_events, num_possible_cpus() * 4);
636         nr_events *= 2;
637 
638         /* Prevent overflows */
639         if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
640             (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
641                 pr_debug("ENOMEM: nr_events too high\n");
642                 return ERR_PTR(-EINVAL);
643         }
644 
645         if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
646                 return ERR_PTR(-EAGAIN);
647 
648         ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
649         if (!ctx)
650                 return ERR_PTR(-ENOMEM);
651 
652         ctx->max_reqs = nr_events;
653 
654         spin_lock_init(&ctx->ctx_lock);
655         spin_lock_init(&ctx->completion_lock);
656         mutex_init(&ctx->ring_lock);
657         /* Protect against page migration throughout kiotx setup by keeping
658          * the ring_lock mutex held until setup is complete. */
659         mutex_lock(&ctx->ring_lock);
660         init_waitqueue_head(&ctx->wait);
661 
662         INIT_LIST_HEAD(&ctx->active_reqs);
663 
664         if (percpu_ref_init(&ctx->users, free_ioctx_users))
665                 goto err;
666 
667         if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs))
668                 goto err;
669 
670         ctx->cpu = alloc_percpu(struct kioctx_cpu);
671         if (!ctx->cpu)
672                 goto err;
673 
674         err = aio_setup_ring(ctx);
675         if (err < 0)
676                 goto err;
677 
678         atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
679         ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
680         if (ctx->req_batch < 1)
681                 ctx->req_batch = 1;
682 
683         /* limit the number of system wide aios */
684         spin_lock(&aio_nr_lock);
685         if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
686             aio_nr + nr_events < aio_nr) {
687                 spin_unlock(&aio_nr_lock);
688                 err = -EAGAIN;
689                 goto err_ctx;
690         }
691         aio_nr += ctx->max_reqs;
692         spin_unlock(&aio_nr_lock);
693 
694         percpu_ref_get(&ctx->users);    /* io_setup() will drop this ref */
695         percpu_ref_get(&ctx->reqs);     /* free_ioctx_users() will drop this */
696 
697         err = ioctx_add_table(ctx, mm);
698         if (err)
699                 goto err_cleanup;
700 
701         /* Release the ring_lock mutex now that all setup is complete. */
702         mutex_unlock(&ctx->ring_lock);
703 
704         pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
705                  ctx, ctx->user_id, mm, ctx->nr_events);
706         return ctx;
707 
708 err_cleanup:
709         aio_nr_sub(ctx->max_reqs);
710 err_ctx:
711         aio_free_ring(ctx);
712 err:
713         mutex_unlock(&ctx->ring_lock);
714         free_percpu(ctx->cpu);
715         percpu_ref_exit(&ctx->reqs);
716         percpu_ref_exit(&ctx->users);
717         kmem_cache_free(kioctx_cachep, ctx);
718         pr_debug("error allocating ioctx %d\n", err);
719         return ERR_PTR(err);
720 }
721 
722 /* kill_ioctx
723  *      Cancels all outstanding aio requests on an aio context.  Used
724  *      when the processes owning a context have all exited to encourage
725  *      the rapid destruction of the kioctx.
726  */
727 static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
728                 struct completion *requests_done)
729 {
730         struct kioctx_table *table;
731 
732         if (atomic_xchg(&ctx->dead, 1))
733                 return -EINVAL;
734 
735 
736         spin_lock(&mm->ioctx_lock);
737         table = rcu_dereference_raw(mm->ioctx_table);
738         WARN_ON(ctx != table->table[ctx->id]);
739         table->table[ctx->id] = NULL;
740         spin_unlock(&mm->ioctx_lock);
741 
742         /* percpu_ref_kill() will do the necessary call_rcu() */
743         wake_up_all(&ctx->wait);
744 
745         /*
746          * It'd be more correct to do this in free_ioctx(), after all
747          * the outstanding kiocbs have finished - but by then io_destroy
748          * has already returned, so io_setup() could potentially return
749          * -EAGAIN with no ioctxs actually in use (as far as userspace
750          *  could tell).
751          */
752         aio_nr_sub(ctx->max_reqs);
753 
754         if (ctx->mmap_size)
755                 vm_munmap(ctx->mmap_base, ctx->mmap_size);
756 
757         ctx->requests_done = requests_done;
758         percpu_ref_kill(&ctx->users);
759         return 0;
760 }
761 
762 /* wait_on_sync_kiocb:
763  *      Waits on the given sync kiocb to complete.
764  */
765 ssize_t wait_on_sync_kiocb(struct kiocb *req)
766 {
767         while (!req->ki_ctx) {
768                 set_current_state(TASK_UNINTERRUPTIBLE);
769                 if (req->ki_ctx)
770                         break;
771                 io_schedule();
772         }
773         __set_current_state(TASK_RUNNING);
774         return req->ki_user_data;
775 }
776 EXPORT_SYMBOL(wait_on_sync_kiocb);
777 
778 /*
779  * exit_aio: called when the last user of mm goes away.  At this point, there is
780  * no way for any new requests to be submited or any of the io_* syscalls to be
781  * called on the context.
782  *
783  * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
784  * them.
785  */
786 void exit_aio(struct mm_struct *mm)
787 {
788         struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
789         int i;
790 
791         if (!table)
792                 return;
793 
794         for (i = 0; i < table->nr; ++i) {
795                 struct kioctx *ctx = table->table[i];
796                 struct completion requests_done =
797                         COMPLETION_INITIALIZER_ONSTACK(requests_done);
798 
799                 if (!ctx)
800                         continue;
801                 /*
802                  * We don't need to bother with munmap() here - exit_mmap(mm)
803                  * is coming and it'll unmap everything. And we simply can't,
804                  * this is not necessarily our ->mm.
805                  * Since kill_ioctx() uses non-zero ->mmap_size as indicator
806                  * that it needs to unmap the area, just set it to 0.
807                  */
808                 ctx->mmap_size = 0;
809                 kill_ioctx(mm, ctx, &requests_done);
810 
811                 /* Wait until all IO for the context are done. */
812                 wait_for_completion(&requests_done);
813         }
814 
815         RCU_INIT_POINTER(mm->ioctx_table, NULL);
816         kfree(table);
817 }
818 
819 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
820 {
821         struct kioctx_cpu *kcpu;
822         unsigned long flags;
823 
824         local_irq_save(flags);
825         kcpu = this_cpu_ptr(ctx->cpu);
826         kcpu->reqs_available += nr;
827 
828         while (kcpu->reqs_available >= ctx->req_batch * 2) {
829                 kcpu->reqs_available -= ctx->req_batch;
830                 atomic_add(ctx->req_batch, &ctx->reqs_available);
831         }
832 
833         local_irq_restore(flags);
834 }
835 
836 static bool get_reqs_available(struct kioctx *ctx)
837 {
838         struct kioctx_cpu *kcpu;
839         bool ret = false;
840         unsigned long flags;
841 
842         local_irq_save(flags);
843         kcpu = this_cpu_ptr(ctx->cpu);
844         if (!kcpu->reqs_available) {
845                 int old, avail = atomic_read(&ctx->reqs_available);
846 
847                 do {
848                         if (avail < ctx->req_batch)
849                                 goto out;
850 
851                         old = avail;
852                         avail = atomic_cmpxchg(&ctx->reqs_available,
853                                                avail, avail - ctx->req_batch);
854                 } while (avail != old);
855 
856                 kcpu->reqs_available += ctx->req_batch;
857         }
858 
859         ret = true;
860         kcpu->reqs_available--;
861 out:
862         local_irq_restore(flags);
863         return ret;
864 }
865 
866 /* refill_reqs_available
867  *      Updates the reqs_available reference counts used for tracking the
868  *      number of free slots in the completion ring.  This can be called
869  *      from aio_complete() (to optimistically update reqs_available) or
870  *      from aio_get_req() (the we're out of events case).  It must be
871  *      called holding ctx->completion_lock.
872  */
873 static void refill_reqs_available(struct kioctx *ctx, unsigned head,
874                                   unsigned tail)
875 {
876         unsigned events_in_ring, completed;
877 
878         /* Clamp head since userland can write to it. */
879         head %= ctx->nr_events;
880         if (head <= tail)
881                 events_in_ring = tail - head;
882         else
883                 events_in_ring = ctx->nr_events - (head - tail);
884 
885         completed = ctx->completed_events;
886         if (events_in_ring < completed)
887                 completed -= events_in_ring;
888         else
889                 completed = 0;
890 
891         if (!completed)
892                 return;
893 
894         ctx->completed_events -= completed;
895         put_reqs_available(ctx, completed);
896 }
897 
898 /* user_refill_reqs_available
899  *      Called to refill reqs_available when aio_get_req() encounters an
900  *      out of space in the completion ring.
901  */
902 static void user_refill_reqs_available(struct kioctx *ctx)
903 {
904         spin_lock_irq(&ctx->completion_lock);
905         if (ctx->completed_events) {
906                 struct aio_ring *ring;
907                 unsigned head;
908 
909                 /* Access of ring->head may race with aio_read_events_ring()
910                  * here, but that's okay since whether we read the old version
911                  * or the new version, and either will be valid.  The important
912                  * part is that head cannot pass tail since we prevent
913                  * aio_complete() from updating tail by holding
914                  * ctx->completion_lock.  Even if head is invalid, the check
915                  * against ctx->completed_events below will make sure we do the
916                  * safe/right thing.
917                  */
918                 ring = kmap_atomic(ctx->ring_pages[0]);
919                 head = ring->head;
920                 kunmap_atomic(ring);
921 
922                 refill_reqs_available(ctx, head, ctx->tail);
923         }
924 
925         spin_unlock_irq(&ctx->completion_lock);
926 }
927 
928 /* aio_get_req
929  *      Allocate a slot for an aio request.
930  * Returns NULL if no requests are free.
931  */
932 static inline struct kiocb *aio_get_req(struct kioctx *ctx)
933 {
934         struct kiocb *req;
935 
936         if (!get_reqs_available(ctx)) {
937                 user_refill_reqs_available(ctx);
938                 if (!get_reqs_available(ctx))
939                         return NULL;
940         }
941 
942         req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
943         if (unlikely(!req))
944                 goto out_put;
945 
946         percpu_ref_get(&ctx->reqs);
947 
948         req->ki_ctx = ctx;
949         return req;
950 out_put:
951         put_reqs_available(ctx, 1);
952         return NULL;
953 }
954 
955 static void kiocb_free(struct kiocb *req)
956 {
957         if (req->ki_filp)
958                 fput(req->ki_filp);
959         if (req->ki_eventfd != NULL)
960                 eventfd_ctx_put(req->ki_eventfd);
961         kmem_cache_free(kiocb_cachep, req);
962 }
963 
964 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
965 {
966         struct aio_ring __user *ring  = (void __user *)ctx_id;
967         struct mm_struct *mm = current->mm;
968         struct kioctx *ctx, *ret = NULL;
969         struct kioctx_table *table;
970         unsigned id;
971 
972         if (get_user(id, &ring->id))
973                 return NULL;
974 
975         rcu_read_lock();
976         table = rcu_dereference(mm->ioctx_table);
977 
978         if (!table || id >= table->nr)
979                 goto out;
980 
981         ctx = table->table[id];
982         if (ctx && ctx->user_id == ctx_id) {
983                 percpu_ref_get(&ctx->users);
984                 ret = ctx;
985         }
986 out:
987         rcu_read_unlock();
988         return ret;
989 }
990 
991 /* aio_complete
992  *      Called when the io request on the given iocb is complete.
993  */
994 void aio_complete(struct kiocb *iocb, long res, long res2)
995 {
996         struct kioctx   *ctx = iocb->ki_ctx;
997         struct aio_ring *ring;
998         struct io_event *ev_page, *event;
999         unsigned tail, pos, head;
1000         unsigned long   flags;
1001 
1002         /*
1003          * Special case handling for sync iocbs:
1004          *  - events go directly into the iocb for fast handling
1005          *  - the sync task with the iocb in its stack holds the single iocb
1006          *    ref, no other paths have a way to get another ref
1007          *  - the sync task helpfully left a reference to itself in the iocb
1008          */
1009         if (is_sync_kiocb(iocb)) {
1010                 iocb->ki_user_data = res;
1011                 smp_wmb();
1012                 iocb->ki_ctx = ERR_PTR(-EXDEV);
1013                 wake_up_process(iocb->ki_obj.tsk);
1014                 return;
1015         }
1016 
1017         if (iocb->ki_list.next) {
1018                 unsigned long flags;
1019 
1020                 spin_lock_irqsave(&ctx->ctx_lock, flags);
1021                 list_del(&iocb->ki_list);
1022                 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1023         }
1024 
1025         /*
1026          * Add a completion event to the ring buffer. Must be done holding
1027          * ctx->completion_lock to prevent other code from messing with the tail
1028          * pointer since we might be called from irq context.
1029          */
1030         spin_lock_irqsave(&ctx->completion_lock, flags);
1031 
1032         tail = ctx->tail;
1033         pos = tail + AIO_EVENTS_OFFSET;
1034 
1035         if (++tail >= ctx->nr_events)
1036                 tail = 0;
1037 
1038         ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1039         event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1040 
1041         event->obj = (u64)(unsigned long)iocb->ki_obj.user;
1042         event->data = iocb->ki_user_data;
1043         event->res = res;
1044         event->res2 = res2;
1045 
1046         kunmap_atomic(ev_page);
1047         flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1048 
1049         pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
1050                  ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
1051                  res, res2);
1052 
1053         /* after flagging the request as done, we
1054          * must never even look at it again
1055          */
1056         smp_wmb();      /* make event visible before updating tail */
1057 
1058         ctx->tail = tail;
1059 
1060         ring = kmap_atomic(ctx->ring_pages[0]);
1061         head = ring->head;
1062         ring->tail = tail;
1063         kunmap_atomic(ring);
1064         flush_dcache_page(ctx->ring_pages[0]);
1065 
1066         ctx->completed_events++;
1067         if (ctx->completed_events > 1)
1068                 refill_reqs_available(ctx, head, tail);
1069         spin_unlock_irqrestore(&ctx->completion_lock, flags);
1070 
1071         pr_debug("added to ring %p at [%u]\n", iocb, tail);
1072 
1073         /*
1074          * Check if the user asked us to deliver the result through an
1075          * eventfd. The eventfd_signal() function is safe to be called
1076          * from IRQ context.
1077          */
1078         if (iocb->ki_eventfd != NULL)
1079                 eventfd_signal(iocb->ki_eventfd, 1);
1080 
1081         /* everything turned out well, dispose of the aiocb. */
1082         kiocb_free(iocb);
1083 
1084         /*
1085          * We have to order our ring_info tail store above and test
1086          * of the wait list below outside the wait lock.  This is
1087          * like in wake_up_bit() where clearing a bit has to be
1088          * ordered with the unlocked test.
1089          */
1090         smp_mb();
1091 
1092         if (waitqueue_active(&ctx->wait))
1093                 wake_up(&ctx->wait);
1094 
1095         percpu_ref_put(&ctx->reqs);
1096 }
1097 EXPORT_SYMBOL(aio_complete);
1098 
1099 /* aio_read_events_ring
1100  *      Pull an event off of the ioctx's event ring.  Returns the number of
1101  *      events fetched
1102  */
1103 static long aio_read_events_ring(struct kioctx *ctx,
1104                                  struct io_event __user *event, long nr)
1105 {
1106         struct aio_ring *ring;
1107         unsigned head, tail, pos;
1108         long ret = 0;
1109         int copy_ret;
1110 
1111         mutex_lock(&ctx->ring_lock);
1112 
1113         /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1114         ring = kmap_atomic(ctx->ring_pages[0]);
1115         head = ring->head;
1116         tail = ring->tail;
1117         kunmap_atomic(ring);
1118 
1119         /*
1120          * Ensure that once we've read the current tail pointer, that
1121          * we also see the events that were stored up to the tail.
1122          */
1123         smp_rmb();
1124 
1125         pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1126 
1127         if (head == tail)
1128                 goto out;
1129 
1130         head %= ctx->nr_events;
1131         tail %= ctx->nr_events;
1132 
1133         while (ret < nr) {
1134                 long avail;
1135                 struct io_event *ev;
1136                 struct page *page;
1137 
1138                 avail = (head <= tail ?  tail : ctx->nr_events) - head;
1139                 if (head == tail)
1140                         break;
1141 
1142                 avail = min(avail, nr - ret);
1143                 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
1144                             ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
1145 
1146                 pos = head + AIO_EVENTS_OFFSET;
1147                 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1148                 pos %= AIO_EVENTS_PER_PAGE;
1149 
1150                 ev = kmap(page);
1151                 copy_ret = copy_to_user(event + ret, ev + pos,
1152                                         sizeof(*ev) * avail);
1153                 kunmap(page);
1154 
1155                 if (unlikely(copy_ret)) {
1156                         ret = -EFAULT;
1157                         goto out;
1158                 }
1159 
1160                 ret += avail;
1161                 head += avail;
1162                 head %= ctx->nr_events;
1163         }
1164 
1165         ring = kmap_atomic(ctx->ring_pages[0]);
1166         ring->head = head;
1167         kunmap_atomic(ring);
1168         flush_dcache_page(ctx->ring_pages[0]);
1169 
1170         pr_debug("%li  h%u t%u\n", ret, head, tail);
1171 out:
1172         mutex_unlock(&ctx->ring_lock);
1173 
1174         return ret;
1175 }
1176 
1177 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1178                             struct io_event __user *event, long *i)
1179 {
1180         long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1181 
1182         if (ret > 0)
1183                 *i += ret;
1184 
1185         if (unlikely(atomic_read(&ctx->dead)))
1186                 ret = -EINVAL;
1187 
1188         if (!*i)
1189                 *i = ret;
1190 
1191         return ret < 0 || *i >= min_nr;
1192 }
1193 
1194 static long read_events(struct kioctx *ctx, long min_nr, long nr,
1195                         struct io_event __user *event,
1196                         struct timespec __user *timeout)
1197 {
1198         ktime_t until = { .tv64 = KTIME_MAX };
1199         long ret = 0;
1200 
1201         if (timeout) {
1202                 struct timespec ts;
1203 
1204                 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1205                         return -EFAULT;
1206 
1207                 until = timespec_to_ktime(ts);
1208         }
1209 
1210         /*
1211          * Note that aio_read_events() is being called as the conditional - i.e.
1212          * we're calling it after prepare_to_wait() has set task state to
1213          * TASK_INTERRUPTIBLE.
1214          *
1215          * But aio_read_events() can block, and if it blocks it's going to flip
1216          * the task state back to TASK_RUNNING.
1217          *
1218          * This should be ok, provided it doesn't flip the state back to
1219          * TASK_RUNNING and return 0 too much - that causes us to spin. That
1220          * will only happen if the mutex_lock() call blocks, and we then find
1221          * the ringbuffer empty. So in practice we should be ok, but it's
1222          * something to be aware of when touching this code.
1223          */
1224         wait_event_interruptible_hrtimeout(ctx->wait,
1225                         aio_read_events(ctx, min_nr, nr, event, &ret), until);
1226 
1227         if (!ret && signal_pending(current))
1228                 ret = -EINTR;
1229 
1230         return ret;
1231 }
1232 
1233 /* sys_io_setup:
1234  *      Create an aio_context capable of receiving at least nr_events.
1235  *      ctxp must not point to an aio_context that already exists, and
1236  *      must be initialized to 0 prior to the call.  On successful
1237  *      creation of the aio_context, *ctxp is filled in with the resulting 
1238  *      handle.  May fail with -EINVAL if *ctxp is not initialized,
1239  *      if the specified nr_events exceeds internal limits.  May fail 
1240  *      with -EAGAIN if the specified nr_events exceeds the user's limit 
1241  *      of available events.  May fail with -ENOMEM if insufficient kernel
1242  *      resources are available.  May fail with -EFAULT if an invalid
1243  *      pointer is passed for ctxp.  Will fail with -ENOSYS if not
1244  *      implemented.
1245  */
1246 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1247 {
1248         struct kioctx *ioctx = NULL;
1249         unsigned long ctx;
1250         long ret;
1251 
1252         ret = get_user(ctx, ctxp);
1253         if (unlikely(ret))
1254                 goto out;
1255 
1256         ret = -EINVAL;
1257         if (unlikely(ctx || nr_events == 0)) {
1258                 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1259                          ctx, nr_events);
1260                 goto out;
1261         }
1262 
1263         ioctx = ioctx_alloc(nr_events);
1264         ret = PTR_ERR(ioctx);
1265         if (!IS_ERR(ioctx)) {
1266                 ret = put_user(ioctx->user_id, ctxp);
1267                 if (ret)
1268                         kill_ioctx(current->mm, ioctx, NULL);
1269                 percpu_ref_put(&ioctx->users);
1270         }
1271 
1272 out:
1273         return ret;
1274 }
1275 
1276 /* sys_io_destroy:
1277  *      Destroy the aio_context specified.  May cancel any outstanding 
1278  *      AIOs and block on completion.  Will fail with -ENOSYS if not
1279  *      implemented.  May fail with -EINVAL if the context pointed to
1280  *      is invalid.
1281  */
1282 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1283 {
1284         struct kioctx *ioctx = lookup_ioctx(ctx);
1285         if (likely(NULL != ioctx)) {
1286                 struct completion requests_done =
1287                         COMPLETION_INITIALIZER_ONSTACK(requests_done);
1288                 int ret;
1289 
1290                 /* Pass requests_done to kill_ioctx() where it can be set
1291                  * in a thread-safe way. If we try to set it here then we have
1292                  * a race condition if two io_destroy() called simultaneously.
1293                  */
1294                 ret = kill_ioctx(current->mm, ioctx, &requests_done);
1295                 percpu_ref_put(&ioctx->users);
1296 
1297                 /* Wait until all IO for the context are done. Otherwise kernel
1298                  * keep using user-space buffers even if user thinks the context
1299                  * is destroyed.
1300                  */
1301                 if (!ret)
1302                         wait_for_completion(&requests_done);
1303 
1304                 return ret;
1305         }
1306         pr_debug("EINVAL: io_destroy: invalid context id\n");
1307         return -EINVAL;
1308 }
1309 
1310 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
1311                             unsigned long, loff_t);
1312 typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
1313 
1314 static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
1315                                      int rw, char __user *buf,
1316                                      unsigned long *nr_segs,
1317                                      struct iovec **iovec,
1318                                      bool compat)
1319 {
1320         ssize_t ret;
1321 
1322         *nr_segs = kiocb->ki_nbytes;
1323 
1324 #ifdef CONFIG_COMPAT
1325         if (compat)
1326                 ret = compat_rw_copy_check_uvector(rw,
1327                                 (struct compat_iovec __user *)buf,
1328                                 *nr_segs, UIO_FASTIOV, *iovec, iovec);
1329         else
1330 #endif
1331                 ret = rw_copy_check_uvector(rw,
1332                                 (struct iovec __user *)buf,
1333                                 *nr_segs, UIO_FASTIOV, *iovec, iovec);
1334         if (ret < 0)
1335                 return ret;
1336 
1337         /* ki_nbytes now reflect bytes instead of segs */
1338         kiocb->ki_nbytes = ret;
1339         return 0;
1340 }
1341 
1342 static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
1343                                        int rw, char __user *buf,
1344                                        unsigned long *nr_segs,
1345                                        struct iovec *iovec)
1346 {
1347         if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes)))
1348                 return -EFAULT;
1349 
1350         iovec->iov_base = buf;
1351         iovec->iov_len = kiocb->ki_nbytes;
1352         *nr_segs = 1;
1353         return 0;
1354 }
1355 
1356 /*
1357  * aio_run_iocb:
1358  *      Performs the initial checks and io submission.
1359  */
1360 static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
1361                             char __user *buf, bool compat)
1362 {
1363         struct file *file = req->ki_filp;
1364         ssize_t ret;
1365         unsigned long nr_segs;
1366         int rw;
1367         fmode_t mode;
1368         aio_rw_op *rw_op;
1369         rw_iter_op *iter_op;
1370         struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1371         struct iov_iter iter;
1372 
1373         switch (opcode) {
1374         case IOCB_CMD_PREAD:
1375         case IOCB_CMD_PREADV:
1376                 mode    = FMODE_READ;
1377                 rw      = READ;
1378                 rw_op   = file->f_op->aio_read;
1379                 iter_op = file->f_op->read_iter;
1380                 goto rw_common;
1381 
1382         case IOCB_CMD_PWRITE:
1383         case IOCB_CMD_PWRITEV:
1384                 mode    = FMODE_WRITE;
1385                 rw      = WRITE;
1386                 rw_op   = file->f_op->aio_write;
1387                 iter_op = file->f_op->write_iter;
1388                 goto rw_common;
1389 rw_common:
1390                 if (unlikely(!(file->f_mode & mode)))
1391                         return -EBADF;
1392 
1393                 if (!rw_op && !iter_op)
1394                         return -EINVAL;
1395 
1396                 ret = (opcode == IOCB_CMD_PREADV ||
1397                        opcode == IOCB_CMD_PWRITEV)
1398                         ? aio_setup_vectored_rw(req, rw, buf, &nr_segs,
1399                                                 &iovec, compat)
1400                         : aio_setup_single_vector(req, rw, buf, &nr_segs,
1401                                                   iovec);
1402                 if (!ret)
1403                         ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1404                 if (ret < 0) {
1405                         if (iovec != inline_vecs)
1406                                 kfree(iovec);
1407                         return ret;
1408                 }
1409 
1410                 req->ki_nbytes = ret;
1411 
1412                 /* XXX: move/kill - rw_verify_area()? */
1413                 /* This matches the pread()/pwrite() logic */
1414                 if (req->ki_pos < 0) {
1415                         ret = -EINVAL;
1416                         break;
1417                 }
1418 
1419                 if (rw == WRITE)
1420                         file_start_write(file);
1421 
1422                 if (iter_op) {
1423                         iov_iter_init(&iter, rw, iovec, nr_segs, req->ki_nbytes);
1424                         ret = iter_op(req, &iter);
1425                 } else {
1426                         ret = rw_op(req, iovec, nr_segs, req->ki_pos);
1427                 }
1428 
1429                 if (rw == WRITE)
1430                         file_end_write(file);
1431                 break;
1432 
1433         case IOCB_CMD_FDSYNC:
1434                 if (!file->f_op->aio_fsync)
1435                         return -EINVAL;
1436 
1437                 ret = file->f_op->aio_fsync(req, 1);
1438                 break;
1439 
1440         case IOCB_CMD_FSYNC:
1441                 if (!file->f_op->aio_fsync)
1442                         return -EINVAL;
1443 
1444                 ret = file->f_op->aio_fsync(req, 0);
1445                 break;
1446 
1447         default:
1448                 pr_debug("EINVAL: no operation provided\n");
1449                 return -EINVAL;
1450         }
1451 
1452         if (iovec != inline_vecs)
1453                 kfree(iovec);
1454 
1455         if (ret != -EIOCBQUEUED) {
1456                 /*
1457                  * There's no easy way to restart the syscall since other AIO's
1458                  * may be already running. Just fail this IO with EINTR.
1459                  */
1460                 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1461                              ret == -ERESTARTNOHAND ||
1462                              ret == -ERESTART_RESTARTBLOCK))
1463                         ret = -EINTR;
1464                 aio_complete(req, ret, 0);
1465         }
1466 
1467         return 0;
1468 }
1469 
1470 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1471                          struct iocb *iocb, bool compat)
1472 {
1473         struct kiocb *req;
1474         ssize_t ret;
1475 
1476         /* enforce forwards compatibility on users */
1477         if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1478                 pr_debug("EINVAL: reserve field set\n");
1479                 return -EINVAL;
1480         }
1481 
1482         /* prevent overflows */
1483         if (unlikely(
1484             (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1485             (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1486             ((ssize_t)iocb->aio_nbytes < 0)
1487            )) {
1488                 pr_debug("EINVAL: io_submit: overflow check\n");
1489                 return -EINVAL;
1490         }
1491 
1492         req = aio_get_req(ctx);
1493         if (unlikely(!req))
1494                 return -EAGAIN;
1495 
1496         req->ki_filp = fget(iocb->aio_fildes);
1497         if (unlikely(!req->ki_filp)) {
1498                 ret = -EBADF;
1499                 goto out_put_req;
1500         }
1501 
1502         if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1503                 /*
1504                  * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1505                  * instance of the file* now. The file descriptor must be
1506                  * an eventfd() fd, and will be signaled for each completed
1507                  * event using the eventfd_signal() function.
1508                  */
1509                 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1510                 if (IS_ERR(req->ki_eventfd)) {
1511                         ret = PTR_ERR(req->ki_eventfd);
1512                         req->ki_eventfd = NULL;
1513                         goto out_put_req;
1514                 }
1515         }
1516 
1517         ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1518         if (unlikely(ret)) {
1519                 pr_debug("EFAULT: aio_key\n");
1520                 goto out_put_req;
1521         }
1522 
1523         req->ki_obj.user = user_iocb;
1524         req->ki_user_data = iocb->aio_data;
1525         req->ki_pos = iocb->aio_offset;
1526         req->ki_nbytes = iocb->aio_nbytes;
1527 
1528         ret = aio_run_iocb(req, iocb->aio_lio_opcode,
1529                            (char __user *)(unsigned long)iocb->aio_buf,
1530                            compat);
1531         if (ret)
1532                 goto out_put_req;
1533 
1534         return 0;
1535 out_put_req:
1536         put_reqs_available(ctx, 1);
1537         percpu_ref_put(&ctx->reqs);
1538         kiocb_free(req);
1539         return ret;
1540 }
1541 
1542 long do_io_submit(aio_context_t ctx_id, long nr,
1543                   struct iocb __user *__user *iocbpp, bool compat)
1544 {
1545         struct kioctx *ctx;
1546         long ret = 0;
1547         int i = 0;
1548         struct blk_plug plug;
1549 
1550         if (unlikely(nr < 0))
1551                 return -EINVAL;
1552 
1553         if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1554                 nr = LONG_MAX/sizeof(*iocbpp);
1555 
1556         if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1557                 return -EFAULT;
1558 
1559         ctx = lookup_ioctx(ctx_id);
1560         if (unlikely(!ctx)) {
1561                 pr_debug("EINVAL: invalid context id\n");
1562                 return -EINVAL;
1563         }
1564 
1565         blk_start_plug(&plug);
1566 
1567         /*
1568          * AKPM: should this return a partial result if some of the IOs were
1569          * successfully submitted?
1570          */
1571         for (i=0; i<nr; i++) {
1572                 struct iocb __user *user_iocb;
1573                 struct iocb tmp;
1574 
1575                 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1576                         ret = -EFAULT;
1577                         break;
1578                 }
1579 
1580                 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1581                         ret = -EFAULT;
1582                         break;
1583                 }
1584 
1585                 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1586                 if (ret)
1587                         break;
1588         }
1589         blk_finish_plug(&plug);
1590 
1591         percpu_ref_put(&ctx->users);
1592         return i ? i : ret;
1593 }
1594 
1595 /* sys_io_submit:
1596  *      Queue the nr iocbs pointed to by iocbpp for processing.  Returns
1597  *      the number of iocbs queued.  May return -EINVAL if the aio_context
1598  *      specified by ctx_id is invalid, if nr is < 0, if the iocb at
1599  *      *iocbpp[0] is not properly initialized, if the operation specified
1600  *      is invalid for the file descriptor in the iocb.  May fail with
1601  *      -EFAULT if any of the data structures point to invalid data.  May
1602  *      fail with -EBADF if the file descriptor specified in the first
1603  *      iocb is invalid.  May fail with -EAGAIN if insufficient resources
1604  *      are available to queue any iocbs.  Will return 0 if nr is 0.  Will
1605  *      fail with -ENOSYS if not implemented.
1606  */
1607 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1608                 struct iocb __user * __user *, iocbpp)
1609 {
1610         return do_io_submit(ctx_id, nr, iocbpp, 0);
1611 }
1612 
1613 /* lookup_kiocb
1614  *      Finds a given iocb for cancellation.
1615  */
1616 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1617                                   u32 key)
1618 {
1619         struct list_head *pos;
1620 
1621         assert_spin_locked(&ctx->ctx_lock);
1622 
1623         if (key != KIOCB_KEY)
1624                 return NULL;
1625 
1626         /* TODO: use a hash or array, this sucks. */
1627         list_for_each(pos, &ctx->active_reqs) {
1628                 struct kiocb *kiocb = list_kiocb(pos);
1629                 if (kiocb->ki_obj.user == iocb)
1630                         return kiocb;
1631         }
1632         return NULL;
1633 }
1634 
1635 /* sys_io_cancel:
1636  *      Attempts to cancel an iocb previously passed to io_submit.  If
1637  *      the operation is successfully cancelled, the resulting event is
1638  *      copied into the memory pointed to by result without being placed
1639  *      into the completion queue and 0 is returned.  May fail with
1640  *      -EFAULT if any of the data structures pointed to are invalid.
1641  *      May fail with -EINVAL if aio_context specified by ctx_id is
1642  *      invalid.  May fail with -EAGAIN if the iocb specified was not
1643  *      cancelled.  Will fail with -ENOSYS if not implemented.
1644  */
1645 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1646                 struct io_event __user *, result)
1647 {
1648         struct kioctx *ctx;
1649         struct kiocb *kiocb;
1650         u32 key;
1651         int ret;
1652 
1653         ret = get_user(key, &iocb->aio_key);
1654         if (unlikely(ret))
1655                 return -EFAULT;
1656 
1657         ctx = lookup_ioctx(ctx_id);
1658         if (unlikely(!ctx))
1659                 return -EINVAL;
1660 
1661         spin_lock_irq(&ctx->ctx_lock);
1662 
1663         kiocb = lookup_kiocb(ctx, iocb, key);
1664         if (kiocb)
1665                 ret = kiocb_cancel(kiocb);
1666         else
1667                 ret = -EINVAL;
1668 
1669         spin_unlock_irq(&ctx->ctx_lock);
1670 
1671         if (!ret) {
1672                 /*
1673                  * The result argument is no longer used - the io_event is
1674                  * always delivered via the ring buffer. -EINPROGRESS indicates
1675                  * cancellation is progress:
1676                  */
1677                 ret = -EINPROGRESS;
1678         }
1679 
1680         percpu_ref_put(&ctx->users);
1681 
1682         return ret;
1683 }
1684 
1685 /* io_getevents:
1686  *      Attempts to read at least min_nr events and up to nr events from
1687  *      the completion queue for the aio_context specified by ctx_id. If
1688  *      it succeeds, the number of read events is returned. May fail with
1689  *      -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1690  *      out of range, if timeout is out of range.  May fail with -EFAULT
1691  *      if any of the memory specified is invalid.  May return 0 or
1692  *      < min_nr if the timeout specified by timeout has elapsed
1693  *      before sufficient events are available, where timeout == NULL
1694  *      specifies an infinite timeout. Note that the timeout pointed to by
1695  *      timeout is relative.  Will fail with -ENOSYS if not implemented.
1696  */
1697 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1698                 long, min_nr,
1699                 long, nr,
1700                 struct io_event __user *, events,
1701                 struct timespec __user *, timeout)
1702 {
1703         struct kioctx *ioctx = lookup_ioctx(ctx_id);
1704         long ret = -EINVAL;
1705 
1706         if (likely(ioctx)) {
1707                 if (likely(min_nr <= nr && min_nr >= 0))
1708                         ret = read_events(ioctx, min_nr, nr, events, timeout);
1709                 percpu_ref_put(&ioctx->users);
1710         }
1711         return ret;
1712 }
1713 

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