xref: /openbmc/linux/fs/aio.c (revision 0e01d176d5788f66dc64a7e61119edb56eb08339)
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  static void __init aio_sysctl_init(void)
246  {
247  	register_sysctl_init("fs", aio_sysctls);
248  }
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  static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
262  {
263  	struct file *file;
264  	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
265  	if (IS_ERR(inode))
266  		return ERR_CAST(inode);
267  
268  	inode->i_mapping->a_ops = &aio_ctx_aops;
269  	inode->i_mapping->private_data = ctx;
270  	inode->i_size = PAGE_SIZE * nr_pages;
271  
272  	file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
273  				O_RDWR, &aio_ring_fops);
274  	if (IS_ERR(file))
275  		iput(inode);
276  	return file;
277  }
278  
279  static int aio_init_fs_context(struct fs_context *fc)
280  {
281  	if (!init_pseudo(fc, AIO_RING_MAGIC))
282  		return -ENOMEM;
283  	fc->s_iflags |= SB_I_NOEXEC;
284  	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  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  	aio_mnt = kern_mount(&aio_fs);
299  	if (IS_ERR(aio_mnt))
300  		panic("Failed to create aio fs mount.");
301  
302  	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
303  	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
304  	aio_sysctl_init();
305  	return 0;
306  }
307  __initcall(aio_setup);
308  
309  static void put_aio_ring_file(struct kioctx *ctx)
310  {
311  	struct file *aio_ring_file = ctx->aio_ring_file;
312  	struct address_space *i_mapping;
313  
314  	if (aio_ring_file) {
315  		truncate_setsize(file_inode(aio_ring_file), 0);
316  
317  		/* Prevent further access to the kioctx from migratepages */
318  		i_mapping = aio_ring_file->f_mapping;
319  		spin_lock(&i_mapping->private_lock);
320  		i_mapping->private_data = NULL;
321  		ctx->aio_ring_file = NULL;
322  		spin_unlock(&i_mapping->private_lock);
323  
324  		fput(aio_ring_file);
325  	}
326  }
327  
328  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  	put_aio_ring_file(ctx);
336  
337  	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  		page = ctx->ring_pages[i];
342  		if (!page)
343  			continue;
344  		ctx->ring_pages[i] = NULL;
345  		put_page(page);
346  	}
347  
348  	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
349  		kfree(ctx->ring_pages);
350  		ctx->ring_pages = NULL;
351  	}
352  }
353  
354  static int aio_ring_mremap(struct vm_area_struct *vma)
355  {
356  	struct file *file = vma->vm_file;
357  	struct mm_struct *mm = vma->vm_mm;
358  	struct kioctx_table *table;
359  	int i, res = -EINVAL;
360  
361  	spin_lock(&mm->ioctx_lock);
362  	rcu_read_lock();
363  	table = rcu_dereference(mm->ioctx_table);
364  	for (i = 0; i < table->nr; i++) {
365  		struct kioctx *ctx;
366  
367  		ctx = rcu_dereference(table->table[i]);
368  		if (ctx && ctx->aio_ring_file == file) {
369  			if (!atomic_read(&ctx->dead)) {
370  				ctx->user_id = ctx->mmap_base = vma->vm_start;
371  				res = 0;
372  			}
373  			break;
374  		}
375  	}
376  
377  	rcu_read_unlock();
378  	spin_unlock(&mm->ioctx_lock);
379  	return res;
380  }
381  
382  static const struct vm_operations_struct aio_ring_vm_ops = {
383  	.mremap		= aio_ring_mremap,
384  #if IS_ENABLED(CONFIG_MMU)
385  	.fault		= filemap_fault,
386  	.map_pages	= filemap_map_pages,
387  	.page_mkwrite	= filemap_page_mkwrite,
388  #endif
389  };
390  
391  static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
392  {
393  	vma->vm_flags |= VM_DONTEXPAND;
394  	vma->vm_ops = &aio_ring_vm_ops;
395  	return 0;
396  }
397  
398  static const struct file_operations aio_ring_fops = {
399  	.mmap = aio_ring_mmap,
400  };
401  
402  #if IS_ENABLED(CONFIG_MIGRATION)
403  static int aio_migratepage(struct address_space *mapping, struct page *new,
404  			struct page *old, enum migrate_mode mode)
405  {
406  	struct kioctx *ctx;
407  	unsigned long flags;
408  	pgoff_t idx;
409  	int rc;
410  
411  	/*
412  	 * We cannot support the _NO_COPY case here, because copy needs to
413  	 * happen under the ctx->completion_lock. That does not work with the
414  	 * migration workflow of MIGRATE_SYNC_NO_COPY.
415  	 */
416  	if (mode == MIGRATE_SYNC_NO_COPY)
417  		return -EINVAL;
418  
419  	rc = 0;
420  
421  	/* mapping->private_lock here protects against the kioctx teardown.  */
422  	spin_lock(&mapping->private_lock);
423  	ctx = mapping->private_data;
424  	if (!ctx) {
425  		rc = -EINVAL;
426  		goto out;
427  	}
428  
429  	/* The ring_lock mutex.  The prevents aio_read_events() from writing
430  	 * to the ring's head, and prevents page migration from mucking in
431  	 * a partially initialized kiotx.
432  	 */
433  	if (!mutex_trylock(&ctx->ring_lock)) {
434  		rc = -EAGAIN;
435  		goto out;
436  	}
437  
438  	idx = old->index;
439  	if (idx < (pgoff_t)ctx->nr_pages) {
440  		/* Make sure the old page hasn't already been changed */
441  		if (ctx->ring_pages[idx] != old)
442  			rc = -EAGAIN;
443  	} else
444  		rc = -EINVAL;
445  
446  	if (rc != 0)
447  		goto out_unlock;
448  
449  	/* Writeback must be complete */
450  	BUG_ON(PageWriteback(old));
451  	get_page(new);
452  
453  	rc = migrate_page_move_mapping(mapping, new, old, 1);
454  	if (rc != MIGRATEPAGE_SUCCESS) {
455  		put_page(new);
456  		goto out_unlock;
457  	}
458  
459  	/* Take completion_lock to prevent other writes to the ring buffer
460  	 * while the old page is copied to the new.  This prevents new
461  	 * events from being lost.
462  	 */
463  	spin_lock_irqsave(&ctx->completion_lock, flags);
464  	migrate_page_copy(new, old);
465  	BUG_ON(ctx->ring_pages[idx] != old);
466  	ctx->ring_pages[idx] = new;
467  	spin_unlock_irqrestore(&ctx->completion_lock, flags);
468  
469  	/* The old page is no longer accessible. */
470  	put_page(old);
471  
472  out_unlock:
473  	mutex_unlock(&ctx->ring_lock);
474  out:
475  	spin_unlock(&mapping->private_lock);
476  	return rc;
477  }
478  #endif
479  
480  static const struct address_space_operations aio_ctx_aops = {
481  	.dirty_folio	= noop_dirty_folio,
482  #if IS_ENABLED(CONFIG_MIGRATION)
483  	.migratepage	= aio_migratepage,
484  #endif
485  };
486  
487  static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
488  {
489  	struct aio_ring *ring;
490  	struct mm_struct *mm = current->mm;
491  	unsigned long size, unused;
492  	int nr_pages;
493  	int i;
494  	struct file *file;
495  
496  	/* Compensate for the ring buffer's head/tail overlap entry */
497  	nr_events += 2;	/* 1 is required, 2 for good luck */
498  
499  	size = sizeof(struct aio_ring);
500  	size += sizeof(struct io_event) * nr_events;
501  
502  	nr_pages = PFN_UP(size);
503  	if (nr_pages < 0)
504  		return -EINVAL;
505  
506  	file = aio_private_file(ctx, nr_pages);
507  	if (IS_ERR(file)) {
508  		ctx->aio_ring_file = NULL;
509  		return -ENOMEM;
510  	}
511  
512  	ctx->aio_ring_file = file;
513  	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
514  			/ sizeof(struct io_event);
515  
516  	ctx->ring_pages = ctx->internal_pages;
517  	if (nr_pages > AIO_RING_PAGES) {
518  		ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
519  					  GFP_KERNEL);
520  		if (!ctx->ring_pages) {
521  			put_aio_ring_file(ctx);
522  			return -ENOMEM;
523  		}
524  	}
525  
526  	for (i = 0; i < nr_pages; i++) {
527  		struct page *page;
528  		page = find_or_create_page(file->f_mapping,
529  					   i, GFP_HIGHUSER | __GFP_ZERO);
530  		if (!page)
531  			break;
532  		pr_debug("pid(%d) page[%d]->count=%d\n",
533  			 current->pid, i, page_count(page));
534  		SetPageUptodate(page);
535  		unlock_page(page);
536  
537  		ctx->ring_pages[i] = page;
538  	}
539  	ctx->nr_pages = i;
540  
541  	if (unlikely(i != nr_pages)) {
542  		aio_free_ring(ctx);
543  		return -ENOMEM;
544  	}
545  
546  	ctx->mmap_size = nr_pages * PAGE_SIZE;
547  	pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
548  
549  	if (mmap_write_lock_killable(mm)) {
550  		ctx->mmap_size = 0;
551  		aio_free_ring(ctx);
552  		return -EINTR;
553  	}
554  
555  	ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
556  				 PROT_READ | PROT_WRITE,
557  				 MAP_SHARED, 0, &unused, NULL);
558  	mmap_write_unlock(mm);
559  	if (IS_ERR((void *)ctx->mmap_base)) {
560  		ctx->mmap_size = 0;
561  		aio_free_ring(ctx);
562  		return -ENOMEM;
563  	}
564  
565  	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
566  
567  	ctx->user_id = ctx->mmap_base;
568  	ctx->nr_events = nr_events; /* trusted copy */
569  
570  	ring = kmap_atomic(ctx->ring_pages[0]);
571  	ring->nr = nr_events;	/* user copy */
572  	ring->id = ~0U;
573  	ring->head = ring->tail = 0;
574  	ring->magic = AIO_RING_MAGIC;
575  	ring->compat_features = AIO_RING_COMPAT_FEATURES;
576  	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
577  	ring->header_length = sizeof(struct aio_ring);
578  	kunmap_atomic(ring);
579  	flush_dcache_page(ctx->ring_pages[0]);
580  
581  	return 0;
582  }
583  
584  #define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
585  #define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
586  #define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
587  
588  void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
589  {
590  	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
591  	struct kioctx *ctx = req->ki_ctx;
592  	unsigned long flags;
593  
594  	if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
595  		return;
596  
597  	spin_lock_irqsave(&ctx->ctx_lock, flags);
598  	list_add_tail(&req->ki_list, &ctx->active_reqs);
599  	req->ki_cancel = cancel;
600  	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
601  }
602  EXPORT_SYMBOL(kiocb_set_cancel_fn);
603  
604  /*
605   * free_ioctx() should be RCU delayed to synchronize against the RCU
606   * protected lookup_ioctx() and also needs process context to call
607   * aio_free_ring().  Use rcu_work.
608   */
609  static void free_ioctx(struct work_struct *work)
610  {
611  	struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
612  					  free_rwork);
613  	pr_debug("freeing %p\n", ctx);
614  
615  	aio_free_ring(ctx);
616  	free_percpu(ctx->cpu);
617  	percpu_ref_exit(&ctx->reqs);
618  	percpu_ref_exit(&ctx->users);
619  	kmem_cache_free(kioctx_cachep, ctx);
620  }
621  
622  static void free_ioctx_reqs(struct percpu_ref *ref)
623  {
624  	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
625  
626  	/* At this point we know that there are no any in-flight requests */
627  	if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
628  		complete(&ctx->rq_wait->comp);
629  
630  	/* Synchronize against RCU protected table->table[] dereferences */
631  	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
632  	queue_rcu_work(system_wq, &ctx->free_rwork);
633  }
634  
635  /*
636   * When this function runs, the kioctx has been removed from the "hash table"
637   * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
638   * now it's safe to cancel any that need to be.
639   */
640  static void free_ioctx_users(struct percpu_ref *ref)
641  {
642  	struct kioctx *ctx = container_of(ref, struct kioctx, users);
643  	struct aio_kiocb *req;
644  
645  	spin_lock_irq(&ctx->ctx_lock);
646  
647  	while (!list_empty(&ctx->active_reqs)) {
648  		req = list_first_entry(&ctx->active_reqs,
649  				       struct aio_kiocb, ki_list);
650  		req->ki_cancel(&req->rw);
651  		list_del_init(&req->ki_list);
652  	}
653  
654  	spin_unlock_irq(&ctx->ctx_lock);
655  
656  	percpu_ref_kill(&ctx->reqs);
657  	percpu_ref_put(&ctx->reqs);
658  }
659  
660  static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
661  {
662  	unsigned i, new_nr;
663  	struct kioctx_table *table, *old;
664  	struct aio_ring *ring;
665  
666  	spin_lock(&mm->ioctx_lock);
667  	table = rcu_dereference_raw(mm->ioctx_table);
668  
669  	while (1) {
670  		if (table)
671  			for (i = 0; i < table->nr; i++)
672  				if (!rcu_access_pointer(table->table[i])) {
673  					ctx->id = i;
674  					rcu_assign_pointer(table->table[i], ctx);
675  					spin_unlock(&mm->ioctx_lock);
676  
677  					/* While kioctx setup is in progress,
678  					 * we are protected from page migration
679  					 * changes ring_pages by ->ring_lock.
680  					 */
681  					ring = kmap_atomic(ctx->ring_pages[0]);
682  					ring->id = ctx->id;
683  					kunmap_atomic(ring);
684  					return 0;
685  				}
686  
687  		new_nr = (table ? table->nr : 1) * 4;
688  		spin_unlock(&mm->ioctx_lock);
689  
690  		table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
691  		if (!table)
692  			return -ENOMEM;
693  
694  		table->nr = new_nr;
695  
696  		spin_lock(&mm->ioctx_lock);
697  		old = rcu_dereference_raw(mm->ioctx_table);
698  
699  		if (!old) {
700  			rcu_assign_pointer(mm->ioctx_table, table);
701  		} else if (table->nr > old->nr) {
702  			memcpy(table->table, old->table,
703  			       old->nr * sizeof(struct kioctx *));
704  
705  			rcu_assign_pointer(mm->ioctx_table, table);
706  			kfree_rcu(old, rcu);
707  		} else {
708  			kfree(table);
709  			table = old;
710  		}
711  	}
712  }
713  
714  static void aio_nr_sub(unsigned nr)
715  {
716  	spin_lock(&aio_nr_lock);
717  	if (WARN_ON(aio_nr - nr > aio_nr))
718  		aio_nr = 0;
719  	else
720  		aio_nr -= nr;
721  	spin_unlock(&aio_nr_lock);
722  }
723  
724  /* ioctx_alloc
725   *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
726   */
727  static struct kioctx *ioctx_alloc(unsigned nr_events)
728  {
729  	struct mm_struct *mm = current->mm;
730  	struct kioctx *ctx;
731  	int err = -ENOMEM;
732  
733  	/*
734  	 * Store the original nr_events -- what userspace passed to io_setup(),
735  	 * for counting against the global limit -- before it changes.
736  	 */
737  	unsigned int max_reqs = nr_events;
738  
739  	/*
740  	 * We keep track of the number of available ringbuffer slots, to prevent
741  	 * overflow (reqs_available), and we also use percpu counters for this.
742  	 *
743  	 * So since up to half the slots might be on other cpu's percpu counters
744  	 * and unavailable, double nr_events so userspace sees what they
745  	 * expected: additionally, we move req_batch slots to/from percpu
746  	 * counters at a time, so make sure that isn't 0:
747  	 */
748  	nr_events = max(nr_events, num_possible_cpus() * 4);
749  	nr_events *= 2;
750  
751  	/* Prevent overflows */
752  	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
753  		pr_debug("ENOMEM: nr_events too high\n");
754  		return ERR_PTR(-EINVAL);
755  	}
756  
757  	if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
758  		return ERR_PTR(-EAGAIN);
759  
760  	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
761  	if (!ctx)
762  		return ERR_PTR(-ENOMEM);
763  
764  	ctx->max_reqs = max_reqs;
765  
766  	spin_lock_init(&ctx->ctx_lock);
767  	spin_lock_init(&ctx->completion_lock);
768  	mutex_init(&ctx->ring_lock);
769  	/* Protect against page migration throughout kiotx setup by keeping
770  	 * the ring_lock mutex held until setup is complete. */
771  	mutex_lock(&ctx->ring_lock);
772  	init_waitqueue_head(&ctx->wait);
773  
774  	INIT_LIST_HEAD(&ctx->active_reqs);
775  
776  	if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
777  		goto err;
778  
779  	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
780  		goto err;
781  
782  	ctx->cpu = alloc_percpu(struct kioctx_cpu);
783  	if (!ctx->cpu)
784  		goto err;
785  
786  	err = aio_setup_ring(ctx, nr_events);
787  	if (err < 0)
788  		goto err;
789  
790  	atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
791  	ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
792  	if (ctx->req_batch < 1)
793  		ctx->req_batch = 1;
794  
795  	/* limit the number of system wide aios */
796  	spin_lock(&aio_nr_lock);
797  	if (aio_nr + ctx->max_reqs > aio_max_nr ||
798  	    aio_nr + ctx->max_reqs < aio_nr) {
799  		spin_unlock(&aio_nr_lock);
800  		err = -EAGAIN;
801  		goto err_ctx;
802  	}
803  	aio_nr += ctx->max_reqs;
804  	spin_unlock(&aio_nr_lock);
805  
806  	percpu_ref_get(&ctx->users);	/* io_setup() will drop this ref */
807  	percpu_ref_get(&ctx->reqs);	/* free_ioctx_users() will drop this */
808  
809  	err = ioctx_add_table(ctx, mm);
810  	if (err)
811  		goto err_cleanup;
812  
813  	/* Release the ring_lock mutex now that all setup is complete. */
814  	mutex_unlock(&ctx->ring_lock);
815  
816  	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
817  		 ctx, ctx->user_id, mm, ctx->nr_events);
818  	return ctx;
819  
820  err_cleanup:
821  	aio_nr_sub(ctx->max_reqs);
822  err_ctx:
823  	atomic_set(&ctx->dead, 1);
824  	if (ctx->mmap_size)
825  		vm_munmap(ctx->mmap_base, ctx->mmap_size);
826  	aio_free_ring(ctx);
827  err:
828  	mutex_unlock(&ctx->ring_lock);
829  	free_percpu(ctx->cpu);
830  	percpu_ref_exit(&ctx->reqs);
831  	percpu_ref_exit(&ctx->users);
832  	kmem_cache_free(kioctx_cachep, ctx);
833  	pr_debug("error allocating ioctx %d\n", err);
834  	return ERR_PTR(err);
835  }
836  
837  /* kill_ioctx
838   *	Cancels all outstanding aio requests on an aio context.  Used
839   *	when the processes owning a context have all exited to encourage
840   *	the rapid destruction of the kioctx.
841   */
842  static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
843  		      struct ctx_rq_wait *wait)
844  {
845  	struct kioctx_table *table;
846  
847  	spin_lock(&mm->ioctx_lock);
848  	if (atomic_xchg(&ctx->dead, 1)) {
849  		spin_unlock(&mm->ioctx_lock);
850  		return -EINVAL;
851  	}
852  
853  	table = rcu_dereference_raw(mm->ioctx_table);
854  	WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
855  	RCU_INIT_POINTER(table->table[ctx->id], NULL);
856  	spin_unlock(&mm->ioctx_lock);
857  
858  	/* free_ioctx_reqs() will do the necessary RCU synchronization */
859  	wake_up_all(&ctx->wait);
860  
861  	/*
862  	 * It'd be more correct to do this in free_ioctx(), after all
863  	 * the outstanding kiocbs have finished - but by then io_destroy
864  	 * has already returned, so io_setup() could potentially return
865  	 * -EAGAIN with no ioctxs actually in use (as far as userspace
866  	 *  could tell).
867  	 */
868  	aio_nr_sub(ctx->max_reqs);
869  
870  	if (ctx->mmap_size)
871  		vm_munmap(ctx->mmap_base, ctx->mmap_size);
872  
873  	ctx->rq_wait = wait;
874  	percpu_ref_kill(&ctx->users);
875  	return 0;
876  }
877  
878  /*
879   * exit_aio: called when the last user of mm goes away.  At this point, there is
880   * no way for any new requests to be submited or any of the io_* syscalls to be
881   * called on the context.
882   *
883   * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
884   * them.
885   */
886  void exit_aio(struct mm_struct *mm)
887  {
888  	struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
889  	struct ctx_rq_wait wait;
890  	int i, skipped;
891  
892  	if (!table)
893  		return;
894  
895  	atomic_set(&wait.count, table->nr);
896  	init_completion(&wait.comp);
897  
898  	skipped = 0;
899  	for (i = 0; i < table->nr; ++i) {
900  		struct kioctx *ctx =
901  			rcu_dereference_protected(table->table[i], true);
902  
903  		if (!ctx) {
904  			skipped++;
905  			continue;
906  		}
907  
908  		/*
909  		 * We don't need to bother with munmap() here - exit_mmap(mm)
910  		 * is coming and it'll unmap everything. And we simply can't,
911  		 * this is not necessarily our ->mm.
912  		 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
913  		 * that it needs to unmap the area, just set it to 0.
914  		 */
915  		ctx->mmap_size = 0;
916  		kill_ioctx(mm, ctx, &wait);
917  	}
918  
919  	if (!atomic_sub_and_test(skipped, &wait.count)) {
920  		/* Wait until all IO for the context are done. */
921  		wait_for_completion(&wait.comp);
922  	}
923  
924  	RCU_INIT_POINTER(mm->ioctx_table, NULL);
925  	kfree(table);
926  }
927  
928  static void put_reqs_available(struct kioctx *ctx, unsigned nr)
929  {
930  	struct kioctx_cpu *kcpu;
931  	unsigned long flags;
932  
933  	local_irq_save(flags);
934  	kcpu = this_cpu_ptr(ctx->cpu);
935  	kcpu->reqs_available += nr;
936  
937  	while (kcpu->reqs_available >= ctx->req_batch * 2) {
938  		kcpu->reqs_available -= ctx->req_batch;
939  		atomic_add(ctx->req_batch, &ctx->reqs_available);
940  	}
941  
942  	local_irq_restore(flags);
943  }
944  
945  static bool __get_reqs_available(struct kioctx *ctx)
946  {
947  	struct kioctx_cpu *kcpu;
948  	bool ret = false;
949  	unsigned long flags;
950  
951  	local_irq_save(flags);
952  	kcpu = this_cpu_ptr(ctx->cpu);
953  	if (!kcpu->reqs_available) {
954  		int old, avail = atomic_read(&ctx->reqs_available);
955  
956  		do {
957  			if (avail < ctx->req_batch)
958  				goto out;
959  
960  			old = avail;
961  			avail = atomic_cmpxchg(&ctx->reqs_available,
962  					       avail, avail - ctx->req_batch);
963  		} while (avail != old);
964  
965  		kcpu->reqs_available += ctx->req_batch;
966  	}
967  
968  	ret = true;
969  	kcpu->reqs_available--;
970  out:
971  	local_irq_restore(flags);
972  	return ret;
973  }
974  
975  /* refill_reqs_available
976   *	Updates the reqs_available reference counts used for tracking the
977   *	number of free slots in the completion ring.  This can be called
978   *	from aio_complete() (to optimistically update reqs_available) or
979   *	from aio_get_req() (the we're out of events case).  It must be
980   *	called holding ctx->completion_lock.
981   */
982  static void refill_reqs_available(struct kioctx *ctx, unsigned head,
983                                    unsigned tail)
984  {
985  	unsigned events_in_ring, completed;
986  
987  	/* Clamp head since userland can write to it. */
988  	head %= ctx->nr_events;
989  	if (head <= tail)
990  		events_in_ring = tail - head;
991  	else
992  		events_in_ring = ctx->nr_events - (head - tail);
993  
994  	completed = ctx->completed_events;
995  	if (events_in_ring < completed)
996  		completed -= events_in_ring;
997  	else
998  		completed = 0;
999  
1000  	if (!completed)
1001  		return;
1002  
1003  	ctx->completed_events -= completed;
1004  	put_reqs_available(ctx, completed);
1005  }
1006  
1007  /* user_refill_reqs_available
1008   *	Called to refill reqs_available when aio_get_req() encounters an
1009   *	out of space in the completion ring.
1010   */
1011  static void user_refill_reqs_available(struct kioctx *ctx)
1012  {
1013  	spin_lock_irq(&ctx->completion_lock);
1014  	if (ctx->completed_events) {
1015  		struct aio_ring *ring;
1016  		unsigned head;
1017  
1018  		/* Access of ring->head may race with aio_read_events_ring()
1019  		 * here, but that's okay since whether we read the old version
1020  		 * or the new version, and either will be valid.  The important
1021  		 * part is that head cannot pass tail since we prevent
1022  		 * aio_complete() from updating tail by holding
1023  		 * ctx->completion_lock.  Even if head is invalid, the check
1024  		 * against ctx->completed_events below will make sure we do the
1025  		 * safe/right thing.
1026  		 */
1027  		ring = kmap_atomic(ctx->ring_pages[0]);
1028  		head = ring->head;
1029  		kunmap_atomic(ring);
1030  
1031  		refill_reqs_available(ctx, head, ctx->tail);
1032  	}
1033  
1034  	spin_unlock_irq(&ctx->completion_lock);
1035  }
1036  
1037  static bool get_reqs_available(struct kioctx *ctx)
1038  {
1039  	if (__get_reqs_available(ctx))
1040  		return true;
1041  	user_refill_reqs_available(ctx);
1042  	return __get_reqs_available(ctx);
1043  }
1044  
1045  /* aio_get_req
1046   *	Allocate a slot for an aio request.
1047   * Returns NULL if no requests are free.
1048   *
1049   * The refcount is initialized to 2 - one for the async op completion,
1050   * one for the synchronous code that does this.
1051   */
1052  static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1053  {
1054  	struct aio_kiocb *req;
1055  
1056  	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1057  	if (unlikely(!req))
1058  		return NULL;
1059  
1060  	if (unlikely(!get_reqs_available(ctx))) {
1061  		kmem_cache_free(kiocb_cachep, req);
1062  		return NULL;
1063  	}
1064  
1065  	percpu_ref_get(&ctx->reqs);
1066  	req->ki_ctx = ctx;
1067  	INIT_LIST_HEAD(&req->ki_list);
1068  	refcount_set(&req->ki_refcnt, 2);
1069  	req->ki_eventfd = NULL;
1070  	return req;
1071  }
1072  
1073  static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1074  {
1075  	struct aio_ring __user *ring  = (void __user *)ctx_id;
1076  	struct mm_struct *mm = current->mm;
1077  	struct kioctx *ctx, *ret = NULL;
1078  	struct kioctx_table *table;
1079  	unsigned id;
1080  
1081  	if (get_user(id, &ring->id))
1082  		return NULL;
1083  
1084  	rcu_read_lock();
1085  	table = rcu_dereference(mm->ioctx_table);
1086  
1087  	if (!table || id >= table->nr)
1088  		goto out;
1089  
1090  	id = array_index_nospec(id, table->nr);
1091  	ctx = rcu_dereference(table->table[id]);
1092  	if (ctx && ctx->user_id == ctx_id) {
1093  		if (percpu_ref_tryget_live(&ctx->users))
1094  			ret = ctx;
1095  	}
1096  out:
1097  	rcu_read_unlock();
1098  	return ret;
1099  }
1100  
1101  static inline void iocb_destroy(struct aio_kiocb *iocb)
1102  {
1103  	if (iocb->ki_eventfd)
1104  		eventfd_ctx_put(iocb->ki_eventfd);
1105  	if (iocb->ki_filp)
1106  		fput(iocb->ki_filp);
1107  	percpu_ref_put(&iocb->ki_ctx->reqs);
1108  	kmem_cache_free(kiocb_cachep, iocb);
1109  }
1110  
1111  /* aio_complete
1112   *	Called when the io request on the given iocb is complete.
1113   */
1114  static void aio_complete(struct aio_kiocb *iocb)
1115  {
1116  	struct kioctx	*ctx = iocb->ki_ctx;
1117  	struct aio_ring	*ring;
1118  	struct io_event	*ev_page, *event;
1119  	unsigned tail, pos, head;
1120  	unsigned long	flags;
1121  
1122  	/*
1123  	 * Add a completion event to the ring buffer. Must be done holding
1124  	 * ctx->completion_lock to prevent other code from messing with the tail
1125  	 * pointer since we might be called from irq context.
1126  	 */
1127  	spin_lock_irqsave(&ctx->completion_lock, flags);
1128  
1129  	tail = ctx->tail;
1130  	pos = tail + AIO_EVENTS_OFFSET;
1131  
1132  	if (++tail >= ctx->nr_events)
1133  		tail = 0;
1134  
1135  	ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1136  	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1137  
1138  	*event = iocb->ki_res;
1139  
1140  	kunmap_atomic(ev_page);
1141  	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1142  
1143  	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1144  		 (void __user *)(unsigned long)iocb->ki_res.obj,
1145  		 iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1146  
1147  	/* after flagging the request as done, we
1148  	 * must never even look at it again
1149  	 */
1150  	smp_wmb();	/* make event visible before updating tail */
1151  
1152  	ctx->tail = tail;
1153  
1154  	ring = kmap_atomic(ctx->ring_pages[0]);
1155  	head = ring->head;
1156  	ring->tail = tail;
1157  	kunmap_atomic(ring);
1158  	flush_dcache_page(ctx->ring_pages[0]);
1159  
1160  	ctx->completed_events++;
1161  	if (ctx->completed_events > 1)
1162  		refill_reqs_available(ctx, head, tail);
1163  	spin_unlock_irqrestore(&ctx->completion_lock, flags);
1164  
1165  	pr_debug("added to ring %p at [%u]\n", iocb, tail);
1166  
1167  	/*
1168  	 * Check if the user asked us to deliver the result through an
1169  	 * eventfd. The eventfd_signal() function is safe to be called
1170  	 * from IRQ context.
1171  	 */
1172  	if (iocb->ki_eventfd)
1173  		eventfd_signal(iocb->ki_eventfd, 1);
1174  
1175  	/*
1176  	 * We have to order our ring_info tail store above and test
1177  	 * of the wait list below outside the wait lock.  This is
1178  	 * like in wake_up_bit() where clearing a bit has to be
1179  	 * ordered with the unlocked test.
1180  	 */
1181  	smp_mb();
1182  
1183  	if (waitqueue_active(&ctx->wait))
1184  		wake_up(&ctx->wait);
1185  }
1186  
1187  static inline void iocb_put(struct aio_kiocb *iocb)
1188  {
1189  	if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1190  		aio_complete(iocb);
1191  		iocb_destroy(iocb);
1192  	}
1193  }
1194  
1195  /* aio_read_events_ring
1196   *	Pull an event off of the ioctx's event ring.  Returns the number of
1197   *	events fetched
1198   */
1199  static long aio_read_events_ring(struct kioctx *ctx,
1200  				 struct io_event __user *event, long nr)
1201  {
1202  	struct aio_ring *ring;
1203  	unsigned head, tail, pos;
1204  	long ret = 0;
1205  	int copy_ret;
1206  
1207  	/*
1208  	 * The mutex can block and wake us up and that will cause
1209  	 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1210  	 * and repeat. This should be rare enough that it doesn't cause
1211  	 * peformance issues. See the comment in read_events() for more detail.
1212  	 */
1213  	sched_annotate_sleep();
1214  	mutex_lock(&ctx->ring_lock);
1215  
1216  	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
1217  	ring = kmap_atomic(ctx->ring_pages[0]);
1218  	head = ring->head;
1219  	tail = ring->tail;
1220  	kunmap_atomic(ring);
1221  
1222  	/*
1223  	 * Ensure that once we've read the current tail pointer, that
1224  	 * we also see the events that were stored up to the tail.
1225  	 */
1226  	smp_rmb();
1227  
1228  	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1229  
1230  	if (head == tail)
1231  		goto out;
1232  
1233  	head %= ctx->nr_events;
1234  	tail %= ctx->nr_events;
1235  
1236  	while (ret < nr) {
1237  		long avail;
1238  		struct io_event *ev;
1239  		struct page *page;
1240  
1241  		avail = (head <= tail ?  tail : ctx->nr_events) - head;
1242  		if (head == tail)
1243  			break;
1244  
1245  		pos = head + AIO_EVENTS_OFFSET;
1246  		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1247  		pos %= AIO_EVENTS_PER_PAGE;
1248  
1249  		avail = min(avail, nr - ret);
1250  		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1251  
1252  		ev = kmap(page);
1253  		copy_ret = copy_to_user(event + ret, ev + pos,
1254  					sizeof(*ev) * avail);
1255  		kunmap(page);
1256  
1257  		if (unlikely(copy_ret)) {
1258  			ret = -EFAULT;
1259  			goto out;
1260  		}
1261  
1262  		ret += avail;
1263  		head += avail;
1264  		head %= ctx->nr_events;
1265  	}
1266  
1267  	ring = kmap_atomic(ctx->ring_pages[0]);
1268  	ring->head = head;
1269  	kunmap_atomic(ring);
1270  	flush_dcache_page(ctx->ring_pages[0]);
1271  
1272  	pr_debug("%li  h%u t%u\n", ret, head, tail);
1273  out:
1274  	mutex_unlock(&ctx->ring_lock);
1275  
1276  	return ret;
1277  }
1278  
1279  static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1280  			    struct io_event __user *event, long *i)
1281  {
1282  	long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1283  
1284  	if (ret > 0)
1285  		*i += ret;
1286  
1287  	if (unlikely(atomic_read(&ctx->dead)))
1288  		ret = -EINVAL;
1289  
1290  	if (!*i)
1291  		*i = ret;
1292  
1293  	return ret < 0 || *i >= min_nr;
1294  }
1295  
1296  static long read_events(struct kioctx *ctx, long min_nr, long nr,
1297  			struct io_event __user *event,
1298  			ktime_t until)
1299  {
1300  	long ret = 0;
1301  
1302  	/*
1303  	 * Note that aio_read_events() is being called as the conditional - i.e.
1304  	 * we're calling it after prepare_to_wait() has set task state to
1305  	 * TASK_INTERRUPTIBLE.
1306  	 *
1307  	 * But aio_read_events() can block, and if it blocks it's going to flip
1308  	 * the task state back to TASK_RUNNING.
1309  	 *
1310  	 * This should be ok, provided it doesn't flip the state back to
1311  	 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1312  	 * will only happen if the mutex_lock() call blocks, and we then find
1313  	 * the ringbuffer empty. So in practice we should be ok, but it's
1314  	 * something to be aware of when touching this code.
1315  	 */
1316  	if (until == 0)
1317  		aio_read_events(ctx, min_nr, nr, event, &ret);
1318  	else
1319  		wait_event_interruptible_hrtimeout(ctx->wait,
1320  				aio_read_events(ctx, min_nr, nr, event, &ret),
1321  				until);
1322  	return ret;
1323  }
1324  
1325  /* sys_io_setup:
1326   *	Create an aio_context capable of receiving at least nr_events.
1327   *	ctxp must not point to an aio_context that already exists, and
1328   *	must be initialized to 0 prior to the call.  On successful
1329   *	creation of the aio_context, *ctxp is filled in with the resulting
1330   *	handle.  May fail with -EINVAL if *ctxp is not initialized,
1331   *	if the specified nr_events exceeds internal limits.  May fail
1332   *	with -EAGAIN if the specified nr_events exceeds the user's limit
1333   *	of available events.  May fail with -ENOMEM if insufficient kernel
1334   *	resources are available.  May fail with -EFAULT if an invalid
1335   *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
1336   *	implemented.
1337   */
1338  SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1339  {
1340  	struct kioctx *ioctx = NULL;
1341  	unsigned long ctx;
1342  	long ret;
1343  
1344  	ret = get_user(ctx, ctxp);
1345  	if (unlikely(ret))
1346  		goto out;
1347  
1348  	ret = -EINVAL;
1349  	if (unlikely(ctx || nr_events == 0)) {
1350  		pr_debug("EINVAL: ctx %lu nr_events %u\n",
1351  		         ctx, nr_events);
1352  		goto out;
1353  	}
1354  
1355  	ioctx = ioctx_alloc(nr_events);
1356  	ret = PTR_ERR(ioctx);
1357  	if (!IS_ERR(ioctx)) {
1358  		ret = put_user(ioctx->user_id, ctxp);
1359  		if (ret)
1360  			kill_ioctx(current->mm, ioctx, NULL);
1361  		percpu_ref_put(&ioctx->users);
1362  	}
1363  
1364  out:
1365  	return ret;
1366  }
1367  
1368  #ifdef CONFIG_COMPAT
1369  COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1370  {
1371  	struct kioctx *ioctx = NULL;
1372  	unsigned long ctx;
1373  	long ret;
1374  
1375  	ret = get_user(ctx, ctx32p);
1376  	if (unlikely(ret))
1377  		goto out;
1378  
1379  	ret = -EINVAL;
1380  	if (unlikely(ctx || nr_events == 0)) {
1381  		pr_debug("EINVAL: ctx %lu nr_events %u\n",
1382  		         ctx, nr_events);
1383  		goto out;
1384  	}
1385  
1386  	ioctx = ioctx_alloc(nr_events);
1387  	ret = PTR_ERR(ioctx);
1388  	if (!IS_ERR(ioctx)) {
1389  		/* truncating is ok because it's a user address */
1390  		ret = put_user((u32)ioctx->user_id, ctx32p);
1391  		if (ret)
1392  			kill_ioctx(current->mm, ioctx, NULL);
1393  		percpu_ref_put(&ioctx->users);
1394  	}
1395  
1396  out:
1397  	return ret;
1398  }
1399  #endif
1400  
1401  /* sys_io_destroy:
1402   *	Destroy the aio_context specified.  May cancel any outstanding
1403   *	AIOs and block on completion.  Will fail with -ENOSYS if not
1404   *	implemented.  May fail with -EINVAL if the context pointed to
1405   *	is invalid.
1406   */
1407  SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1408  {
1409  	struct kioctx *ioctx = lookup_ioctx(ctx);
1410  	if (likely(NULL != ioctx)) {
1411  		struct ctx_rq_wait wait;
1412  		int ret;
1413  
1414  		init_completion(&wait.comp);
1415  		atomic_set(&wait.count, 1);
1416  
1417  		/* Pass requests_done to kill_ioctx() where it can be set
1418  		 * in a thread-safe way. If we try to set it here then we have
1419  		 * a race condition if two io_destroy() called simultaneously.
1420  		 */
1421  		ret = kill_ioctx(current->mm, ioctx, &wait);
1422  		percpu_ref_put(&ioctx->users);
1423  
1424  		/* Wait until all IO for the context are done. Otherwise kernel
1425  		 * keep using user-space buffers even if user thinks the context
1426  		 * is destroyed.
1427  		 */
1428  		if (!ret)
1429  			wait_for_completion(&wait.comp);
1430  
1431  		return ret;
1432  	}
1433  	pr_debug("EINVAL: invalid context id\n");
1434  	return -EINVAL;
1435  }
1436  
1437  static void aio_remove_iocb(struct aio_kiocb *iocb)
1438  {
1439  	struct kioctx *ctx = iocb->ki_ctx;
1440  	unsigned long flags;
1441  
1442  	spin_lock_irqsave(&ctx->ctx_lock, flags);
1443  	list_del(&iocb->ki_list);
1444  	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1445  }
1446  
1447  static void aio_complete_rw(struct kiocb *kiocb, long res)
1448  {
1449  	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1450  
1451  	if (!list_empty_careful(&iocb->ki_list))
1452  		aio_remove_iocb(iocb);
1453  
1454  	if (kiocb->ki_flags & IOCB_WRITE) {
1455  		struct inode *inode = file_inode(kiocb->ki_filp);
1456  
1457  		/*
1458  		 * Tell lockdep we inherited freeze protection from submission
1459  		 * thread.
1460  		 */
1461  		if (S_ISREG(inode->i_mode))
1462  			__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
1463  		file_end_write(kiocb->ki_filp);
1464  	}
1465  
1466  	iocb->ki_res.res = res;
1467  	iocb->ki_res.res2 = 0;
1468  	iocb_put(iocb);
1469  }
1470  
1471  static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1472  {
1473  	int ret;
1474  
1475  	req->ki_complete = aio_complete_rw;
1476  	req->private = NULL;
1477  	req->ki_pos = iocb->aio_offset;
1478  	req->ki_flags = iocb_flags(req->ki_filp);
1479  	if (iocb->aio_flags & IOCB_FLAG_RESFD)
1480  		req->ki_flags |= IOCB_EVENTFD;
1481  	if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1482  		/*
1483  		 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1484  		 * aio_reqprio is interpreted as an I/O scheduling
1485  		 * class and priority.
1486  		 */
1487  		ret = ioprio_check_cap(iocb->aio_reqprio);
1488  		if (ret) {
1489  			pr_debug("aio ioprio check cap error: %d\n", ret);
1490  			return ret;
1491  		}
1492  
1493  		req->ki_ioprio = iocb->aio_reqprio;
1494  	} else
1495  		req->ki_ioprio = get_current_ioprio();
1496  
1497  	ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
1498  	if (unlikely(ret))
1499  		return ret;
1500  
1501  	req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1502  	return 0;
1503  }
1504  
1505  static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1506  		struct iovec **iovec, bool vectored, bool compat,
1507  		struct iov_iter *iter)
1508  {
1509  	void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1510  	size_t len = iocb->aio_nbytes;
1511  
1512  	if (!vectored) {
1513  		ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
1514  		*iovec = NULL;
1515  		return ret;
1516  	}
1517  
1518  	return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1519  }
1520  
1521  static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1522  {
1523  	switch (ret) {
1524  	case -EIOCBQUEUED:
1525  		break;
1526  	case -ERESTARTSYS:
1527  	case -ERESTARTNOINTR:
1528  	case -ERESTARTNOHAND:
1529  	case -ERESTART_RESTARTBLOCK:
1530  		/*
1531  		 * There's no easy way to restart the syscall since other AIO's
1532  		 * may be already running. Just fail this IO with EINTR.
1533  		 */
1534  		ret = -EINTR;
1535  		fallthrough;
1536  	default:
1537  		req->ki_complete(req, ret);
1538  	}
1539  }
1540  
1541  static int aio_read(struct kiocb *req, const struct iocb *iocb,
1542  			bool vectored, bool compat)
1543  {
1544  	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1545  	struct iov_iter iter;
1546  	struct file *file;
1547  	int ret;
1548  
1549  	ret = aio_prep_rw(req, iocb);
1550  	if (ret)
1551  		return ret;
1552  	file = req->ki_filp;
1553  	if (unlikely(!(file->f_mode & FMODE_READ)))
1554  		return -EBADF;
1555  	if (unlikely(!file->f_op->read_iter))
1556  		return -EINVAL;
1557  
1558  	ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
1559  	if (ret < 0)
1560  		return ret;
1561  	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1562  	if (!ret)
1563  		aio_rw_done(req, call_read_iter(file, req, &iter));
1564  	kfree(iovec);
1565  	return ret;
1566  }
1567  
1568  static int aio_write(struct kiocb *req, const struct iocb *iocb,
1569  			 bool vectored, bool compat)
1570  {
1571  	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1572  	struct iov_iter iter;
1573  	struct file *file;
1574  	int ret;
1575  
1576  	ret = aio_prep_rw(req, iocb);
1577  	if (ret)
1578  		return ret;
1579  	file = req->ki_filp;
1580  
1581  	if (unlikely(!(file->f_mode & FMODE_WRITE)))
1582  		return -EBADF;
1583  	if (unlikely(!file->f_op->write_iter))
1584  		return -EINVAL;
1585  
1586  	ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
1587  	if (ret < 0)
1588  		return ret;
1589  	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1590  	if (!ret) {
1591  		/*
1592  		 * Open-code file_start_write here to grab freeze protection,
1593  		 * which will be released by another thread in
1594  		 * aio_complete_rw().  Fool lockdep by telling it the lock got
1595  		 * released so that it doesn't complain about the held lock when
1596  		 * we return to userspace.
1597  		 */
1598  		if (S_ISREG(file_inode(file)->i_mode)) {
1599  			sb_start_write(file_inode(file)->i_sb);
1600  			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1601  		}
1602  		req->ki_flags |= IOCB_WRITE;
1603  		aio_rw_done(req, call_write_iter(file, req, &iter));
1604  	}
1605  	kfree(iovec);
1606  	return ret;
1607  }
1608  
1609  static void aio_fsync_work(struct work_struct *work)
1610  {
1611  	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1612  	const struct cred *old_cred = override_creds(iocb->fsync.creds);
1613  
1614  	iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1615  	revert_creds(old_cred);
1616  	put_cred(iocb->fsync.creds);
1617  	iocb_put(iocb);
1618  }
1619  
1620  static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1621  		     bool datasync)
1622  {
1623  	if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1624  			iocb->aio_rw_flags))
1625  		return -EINVAL;
1626  
1627  	if (unlikely(!req->file->f_op->fsync))
1628  		return -EINVAL;
1629  
1630  	req->creds = prepare_creds();
1631  	if (!req->creds)
1632  		return -ENOMEM;
1633  
1634  	req->datasync = datasync;
1635  	INIT_WORK(&req->work, aio_fsync_work);
1636  	schedule_work(&req->work);
1637  	return 0;
1638  }
1639  
1640  static void aio_poll_put_work(struct work_struct *work)
1641  {
1642  	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1643  	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1644  
1645  	iocb_put(iocb);
1646  }
1647  
1648  /*
1649   * Safely lock the waitqueue which the request is on, synchronizing with the
1650   * case where the ->poll() provider decides to free its waitqueue early.
1651   *
1652   * Returns true on success, meaning that req->head->lock was locked, req->wait
1653   * is on req->head, and an RCU read lock was taken.  Returns false if the
1654   * request was already removed from its waitqueue (which might no longer exist).
1655   */
1656  static bool poll_iocb_lock_wq(struct poll_iocb *req)
1657  {
1658  	wait_queue_head_t *head;
1659  
1660  	/*
1661  	 * While we hold the waitqueue lock and the waitqueue is nonempty,
1662  	 * wake_up_pollfree() will wait for us.  However, taking the waitqueue
1663  	 * lock in the first place can race with the waitqueue being freed.
1664  	 *
1665  	 * We solve this as eventpoll does: by taking advantage of the fact that
1666  	 * all users of wake_up_pollfree() will RCU-delay the actual free.  If
1667  	 * we enter rcu_read_lock() and see that the pointer to the queue is
1668  	 * non-NULL, we can then lock it without the memory being freed out from
1669  	 * under us, then check whether the request is still on the queue.
1670  	 *
1671  	 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1672  	 * case the caller deletes the entry from the queue, leaving it empty.
1673  	 * In that case, only RCU prevents the queue memory from being freed.
1674  	 */
1675  	rcu_read_lock();
1676  	head = smp_load_acquire(&req->head);
1677  	if (head) {
1678  		spin_lock(&head->lock);
1679  		if (!list_empty(&req->wait.entry))
1680  			return true;
1681  		spin_unlock(&head->lock);
1682  	}
1683  	rcu_read_unlock();
1684  	return false;
1685  }
1686  
1687  static void poll_iocb_unlock_wq(struct poll_iocb *req)
1688  {
1689  	spin_unlock(&req->head->lock);
1690  	rcu_read_unlock();
1691  }
1692  
1693  static void aio_poll_complete_work(struct work_struct *work)
1694  {
1695  	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1696  	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1697  	struct poll_table_struct pt = { ._key = req->events };
1698  	struct kioctx *ctx = iocb->ki_ctx;
1699  	__poll_t mask = 0;
1700  
1701  	if (!READ_ONCE(req->cancelled))
1702  		mask = vfs_poll(req->file, &pt) & req->events;
1703  
1704  	/*
1705  	 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1706  	 * calling ->ki_cancel.  We need the ctx_lock roundtrip here to
1707  	 * synchronize with them.  In the cancellation case the list_del_init
1708  	 * itself is not actually needed, but harmless so we keep it in to
1709  	 * avoid further branches in the fast path.
1710  	 */
1711  	spin_lock_irq(&ctx->ctx_lock);
1712  	if (poll_iocb_lock_wq(req)) {
1713  		if (!mask && !READ_ONCE(req->cancelled)) {
1714  			/*
1715  			 * The request isn't actually ready to be completed yet.
1716  			 * Reschedule completion if another wakeup came in.
1717  			 */
1718  			if (req->work_need_resched) {
1719  				schedule_work(&req->work);
1720  				req->work_need_resched = false;
1721  			} else {
1722  				req->work_scheduled = false;
1723  			}
1724  			poll_iocb_unlock_wq(req);
1725  			spin_unlock_irq(&ctx->ctx_lock);
1726  			return;
1727  		}
1728  		list_del_init(&req->wait.entry);
1729  		poll_iocb_unlock_wq(req);
1730  	} /* else, POLLFREE has freed the waitqueue, so we must complete */
1731  	list_del_init(&iocb->ki_list);
1732  	iocb->ki_res.res = mangle_poll(mask);
1733  	spin_unlock_irq(&ctx->ctx_lock);
1734  
1735  	iocb_put(iocb);
1736  }
1737  
1738  /* assumes we are called with irqs disabled */
1739  static int aio_poll_cancel(struct kiocb *iocb)
1740  {
1741  	struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1742  	struct poll_iocb *req = &aiocb->poll;
1743  
1744  	if (poll_iocb_lock_wq(req)) {
1745  		WRITE_ONCE(req->cancelled, true);
1746  		if (!req->work_scheduled) {
1747  			schedule_work(&aiocb->poll.work);
1748  			req->work_scheduled = true;
1749  		}
1750  		poll_iocb_unlock_wq(req);
1751  	} /* else, the request was force-cancelled by POLLFREE already */
1752  
1753  	return 0;
1754  }
1755  
1756  static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1757  		void *key)
1758  {
1759  	struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1760  	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1761  	__poll_t mask = key_to_poll(key);
1762  	unsigned long flags;
1763  
1764  	/* for instances that support it check for an event match first: */
1765  	if (mask && !(mask & req->events))
1766  		return 0;
1767  
1768  	/*
1769  	 * Complete the request inline if possible.  This requires that three
1770  	 * conditions be met:
1771  	 *   1. An event mask must have been passed.  If a plain wakeup was done
1772  	 *	instead, then mask == 0 and we have to call vfs_poll() to get
1773  	 *	the events, so inline completion isn't possible.
1774  	 *   2. The completion work must not have already been scheduled.
1775  	 *   3. ctx_lock must not be busy.  We have to use trylock because we
1776  	 *	already hold the waitqueue lock, so this inverts the normal
1777  	 *	locking order.  Use irqsave/irqrestore because not all
1778  	 *	filesystems (e.g. fuse) call this function with IRQs disabled,
1779  	 *	yet IRQs have to be disabled before ctx_lock is obtained.
1780  	 */
1781  	if (mask && !req->work_scheduled &&
1782  	    spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1783  		struct kioctx *ctx = iocb->ki_ctx;
1784  
1785  		list_del_init(&req->wait.entry);
1786  		list_del(&iocb->ki_list);
1787  		iocb->ki_res.res = mangle_poll(mask);
1788  		if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1789  			iocb = NULL;
1790  			INIT_WORK(&req->work, aio_poll_put_work);
1791  			schedule_work(&req->work);
1792  		}
1793  		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1794  		if (iocb)
1795  			iocb_put(iocb);
1796  	} else {
1797  		/*
1798  		 * Schedule the completion work if needed.  If it was already
1799  		 * scheduled, record that another wakeup came in.
1800  		 *
1801  		 * Don't remove the request from the waitqueue here, as it might
1802  		 * not actually be complete yet (we won't know until vfs_poll()
1803  		 * is called), and we must not miss any wakeups.  POLLFREE is an
1804  		 * exception to this; see below.
1805  		 */
1806  		if (req->work_scheduled) {
1807  			req->work_need_resched = true;
1808  		} else {
1809  			schedule_work(&req->work);
1810  			req->work_scheduled = true;
1811  		}
1812  
1813  		/*
1814  		 * If the waitqueue is being freed early but we can't complete
1815  		 * the request inline, we have to tear down the request as best
1816  		 * we can.  That means immediately removing the request from its
1817  		 * waitqueue and preventing all further accesses to the
1818  		 * waitqueue via the request.  We also need to schedule the
1819  		 * completion work (done above).  Also mark the request as
1820  		 * cancelled, to potentially skip an unneeded call to ->poll().
1821  		 */
1822  		if (mask & POLLFREE) {
1823  			WRITE_ONCE(req->cancelled, true);
1824  			list_del_init(&req->wait.entry);
1825  
1826  			/*
1827  			 * Careful: this *must* be the last step, since as soon
1828  			 * as req->head is NULL'ed out, the request can be
1829  			 * completed and freed, since aio_poll_complete_work()
1830  			 * will no longer need to take the waitqueue lock.
1831  			 */
1832  			smp_store_release(&req->head, NULL);
1833  		}
1834  	}
1835  	return 1;
1836  }
1837  
1838  struct aio_poll_table {
1839  	struct poll_table_struct	pt;
1840  	struct aio_kiocb		*iocb;
1841  	bool				queued;
1842  	int				error;
1843  };
1844  
1845  static void
1846  aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1847  		struct poll_table_struct *p)
1848  {
1849  	struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1850  
1851  	/* multiple wait queues per file are not supported */
1852  	if (unlikely(pt->queued)) {
1853  		pt->error = -EINVAL;
1854  		return;
1855  	}
1856  
1857  	pt->queued = true;
1858  	pt->error = 0;
1859  	pt->iocb->poll.head = head;
1860  	add_wait_queue(head, &pt->iocb->poll.wait);
1861  }
1862  
1863  static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1864  {
1865  	struct kioctx *ctx = aiocb->ki_ctx;
1866  	struct poll_iocb *req = &aiocb->poll;
1867  	struct aio_poll_table apt;
1868  	bool cancel = false;
1869  	__poll_t mask;
1870  
1871  	/* reject any unknown events outside the normal event mask. */
1872  	if ((u16)iocb->aio_buf != iocb->aio_buf)
1873  		return -EINVAL;
1874  	/* reject fields that are not defined for poll */
1875  	if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1876  		return -EINVAL;
1877  
1878  	INIT_WORK(&req->work, aio_poll_complete_work);
1879  	req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1880  
1881  	req->head = NULL;
1882  	req->cancelled = false;
1883  	req->work_scheduled = false;
1884  	req->work_need_resched = false;
1885  
1886  	apt.pt._qproc = aio_poll_queue_proc;
1887  	apt.pt._key = req->events;
1888  	apt.iocb = aiocb;
1889  	apt.queued = false;
1890  	apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1891  
1892  	/* initialized the list so that we can do list_empty checks */
1893  	INIT_LIST_HEAD(&req->wait.entry);
1894  	init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1895  
1896  	mask = vfs_poll(req->file, &apt.pt) & req->events;
1897  	spin_lock_irq(&ctx->ctx_lock);
1898  	if (likely(apt.queued)) {
1899  		bool on_queue = poll_iocb_lock_wq(req);
1900  
1901  		if (!on_queue || req->work_scheduled) {
1902  			/*
1903  			 * aio_poll_wake() already either scheduled the async
1904  			 * completion work, or completed the request inline.
1905  			 */
1906  			if (apt.error) /* unsupported case: multiple queues */
1907  				cancel = true;
1908  			apt.error = 0;
1909  			mask = 0;
1910  		}
1911  		if (mask || apt.error) {
1912  			/* Steal to complete synchronously. */
1913  			list_del_init(&req->wait.entry);
1914  		} else if (cancel) {
1915  			/* Cancel if possible (may be too late though). */
1916  			WRITE_ONCE(req->cancelled, true);
1917  		} else if (on_queue) {
1918  			/*
1919  			 * Actually waiting for an event, so add the request to
1920  			 * active_reqs so that it can be cancelled if needed.
1921  			 */
1922  			list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1923  			aiocb->ki_cancel = aio_poll_cancel;
1924  		}
1925  		if (on_queue)
1926  			poll_iocb_unlock_wq(req);
1927  	}
1928  	if (mask) { /* no async, we'd stolen it */
1929  		aiocb->ki_res.res = mangle_poll(mask);
1930  		apt.error = 0;
1931  	}
1932  	spin_unlock_irq(&ctx->ctx_lock);
1933  	if (mask)
1934  		iocb_put(aiocb);
1935  	return apt.error;
1936  }
1937  
1938  static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1939  			   struct iocb __user *user_iocb, struct aio_kiocb *req,
1940  			   bool compat)
1941  {
1942  	req->ki_filp = fget(iocb->aio_fildes);
1943  	if (unlikely(!req->ki_filp))
1944  		return -EBADF;
1945  
1946  	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1947  		struct eventfd_ctx *eventfd;
1948  		/*
1949  		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1950  		 * instance of the file* now. The file descriptor must be
1951  		 * an eventfd() fd, and will be signaled for each completed
1952  		 * event using the eventfd_signal() function.
1953  		 */
1954  		eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1955  		if (IS_ERR(eventfd))
1956  			return PTR_ERR(eventfd);
1957  
1958  		req->ki_eventfd = eventfd;
1959  	}
1960  
1961  	if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1962  		pr_debug("EFAULT: aio_key\n");
1963  		return -EFAULT;
1964  	}
1965  
1966  	req->ki_res.obj = (u64)(unsigned long)user_iocb;
1967  	req->ki_res.data = iocb->aio_data;
1968  	req->ki_res.res = 0;
1969  	req->ki_res.res2 = 0;
1970  
1971  	switch (iocb->aio_lio_opcode) {
1972  	case IOCB_CMD_PREAD:
1973  		return aio_read(&req->rw, iocb, false, compat);
1974  	case IOCB_CMD_PWRITE:
1975  		return aio_write(&req->rw, iocb, false, compat);
1976  	case IOCB_CMD_PREADV:
1977  		return aio_read(&req->rw, iocb, true, compat);
1978  	case IOCB_CMD_PWRITEV:
1979  		return aio_write(&req->rw, iocb, true, compat);
1980  	case IOCB_CMD_FSYNC:
1981  		return aio_fsync(&req->fsync, iocb, false);
1982  	case IOCB_CMD_FDSYNC:
1983  		return aio_fsync(&req->fsync, iocb, true);
1984  	case IOCB_CMD_POLL:
1985  		return aio_poll(req, iocb);
1986  	default:
1987  		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1988  		return -EINVAL;
1989  	}
1990  }
1991  
1992  static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1993  			 bool compat)
1994  {
1995  	struct aio_kiocb *req;
1996  	struct iocb iocb;
1997  	int err;
1998  
1999  	if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
2000  		return -EFAULT;
2001  
2002  	/* enforce forwards compatibility on users */
2003  	if (unlikely(iocb.aio_reserved2)) {
2004  		pr_debug("EINVAL: reserve field set\n");
2005  		return -EINVAL;
2006  	}
2007  
2008  	/* prevent overflows */
2009  	if (unlikely(
2010  	    (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
2011  	    (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
2012  	    ((ssize_t)iocb.aio_nbytes < 0)
2013  	   )) {
2014  		pr_debug("EINVAL: overflow check\n");
2015  		return -EINVAL;
2016  	}
2017  
2018  	req = aio_get_req(ctx);
2019  	if (unlikely(!req))
2020  		return -EAGAIN;
2021  
2022  	err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
2023  
2024  	/* Done with the synchronous reference */
2025  	iocb_put(req);
2026  
2027  	/*
2028  	 * If err is 0, we'd either done aio_complete() ourselves or have
2029  	 * arranged for that to be done asynchronously.  Anything non-zero
2030  	 * means that we need to destroy req ourselves.
2031  	 */
2032  	if (unlikely(err)) {
2033  		iocb_destroy(req);
2034  		put_reqs_available(ctx, 1);
2035  	}
2036  	return err;
2037  }
2038  
2039  /* sys_io_submit:
2040   *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
2041   *	the number of iocbs queued.  May return -EINVAL if the aio_context
2042   *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
2043   *	*iocbpp[0] is not properly initialized, if the operation specified
2044   *	is invalid for the file descriptor in the iocb.  May fail with
2045   *	-EFAULT if any of the data structures point to invalid data.  May
2046   *	fail with -EBADF if the file descriptor specified in the first
2047   *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
2048   *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
2049   *	fail with -ENOSYS if not implemented.
2050   */
2051  SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2052  		struct iocb __user * __user *, iocbpp)
2053  {
2054  	struct kioctx *ctx;
2055  	long ret = 0;
2056  	int i = 0;
2057  	struct blk_plug plug;
2058  
2059  	if (unlikely(nr < 0))
2060  		return -EINVAL;
2061  
2062  	ctx = lookup_ioctx(ctx_id);
2063  	if (unlikely(!ctx)) {
2064  		pr_debug("EINVAL: invalid context id\n");
2065  		return -EINVAL;
2066  	}
2067  
2068  	if (nr > ctx->nr_events)
2069  		nr = ctx->nr_events;
2070  
2071  	if (nr > AIO_PLUG_THRESHOLD)
2072  		blk_start_plug(&plug);
2073  	for (i = 0; i < nr; i++) {
2074  		struct iocb __user *user_iocb;
2075  
2076  		if (unlikely(get_user(user_iocb, iocbpp + i))) {
2077  			ret = -EFAULT;
2078  			break;
2079  		}
2080  
2081  		ret = io_submit_one(ctx, user_iocb, false);
2082  		if (ret)
2083  			break;
2084  	}
2085  	if (nr > AIO_PLUG_THRESHOLD)
2086  		blk_finish_plug(&plug);
2087  
2088  	percpu_ref_put(&ctx->users);
2089  	return i ? i : ret;
2090  }
2091  
2092  #ifdef CONFIG_COMPAT
2093  COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2094  		       int, nr, compat_uptr_t __user *, iocbpp)
2095  {
2096  	struct kioctx *ctx;
2097  	long ret = 0;
2098  	int i = 0;
2099  	struct blk_plug plug;
2100  
2101  	if (unlikely(nr < 0))
2102  		return -EINVAL;
2103  
2104  	ctx = lookup_ioctx(ctx_id);
2105  	if (unlikely(!ctx)) {
2106  		pr_debug("EINVAL: invalid context id\n");
2107  		return -EINVAL;
2108  	}
2109  
2110  	if (nr > ctx->nr_events)
2111  		nr = ctx->nr_events;
2112  
2113  	if (nr > AIO_PLUG_THRESHOLD)
2114  		blk_start_plug(&plug);
2115  	for (i = 0; i < nr; i++) {
2116  		compat_uptr_t user_iocb;
2117  
2118  		if (unlikely(get_user(user_iocb, iocbpp + i))) {
2119  			ret = -EFAULT;
2120  			break;
2121  		}
2122  
2123  		ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2124  		if (ret)
2125  			break;
2126  	}
2127  	if (nr > AIO_PLUG_THRESHOLD)
2128  		blk_finish_plug(&plug);
2129  
2130  	percpu_ref_put(&ctx->users);
2131  	return i ? i : ret;
2132  }
2133  #endif
2134  
2135  /* sys_io_cancel:
2136   *	Attempts to cancel an iocb previously passed to io_submit.  If
2137   *	the operation is successfully cancelled, the resulting event is
2138   *	copied into the memory pointed to by result without being placed
2139   *	into the completion queue and 0 is returned.  May fail with
2140   *	-EFAULT if any of the data structures pointed to are invalid.
2141   *	May fail with -EINVAL if aio_context specified by ctx_id is
2142   *	invalid.  May fail with -EAGAIN if the iocb specified was not
2143   *	cancelled.  Will fail with -ENOSYS if not implemented.
2144   */
2145  SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2146  		struct io_event __user *, result)
2147  {
2148  	struct kioctx *ctx;
2149  	struct aio_kiocb *kiocb;
2150  	int ret = -EINVAL;
2151  	u32 key;
2152  	u64 obj = (u64)(unsigned long)iocb;
2153  
2154  	if (unlikely(get_user(key, &iocb->aio_key)))
2155  		return -EFAULT;
2156  	if (unlikely(key != KIOCB_KEY))
2157  		return -EINVAL;
2158  
2159  	ctx = lookup_ioctx(ctx_id);
2160  	if (unlikely(!ctx))
2161  		return -EINVAL;
2162  
2163  	spin_lock_irq(&ctx->ctx_lock);
2164  	/* TODO: use a hash or array, this sucks. */
2165  	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2166  		if (kiocb->ki_res.obj == obj) {
2167  			ret = kiocb->ki_cancel(&kiocb->rw);
2168  			list_del_init(&kiocb->ki_list);
2169  			break;
2170  		}
2171  	}
2172  	spin_unlock_irq(&ctx->ctx_lock);
2173  
2174  	if (!ret) {
2175  		/*
2176  		 * The result argument is no longer used - the io_event is
2177  		 * always delivered via the ring buffer. -EINPROGRESS indicates
2178  		 * cancellation is progress:
2179  		 */
2180  		ret = -EINPROGRESS;
2181  	}
2182  
2183  	percpu_ref_put(&ctx->users);
2184  
2185  	return ret;
2186  }
2187  
2188  static long do_io_getevents(aio_context_t ctx_id,
2189  		long min_nr,
2190  		long nr,
2191  		struct io_event __user *events,
2192  		struct timespec64 *ts)
2193  {
2194  	ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2195  	struct kioctx *ioctx = lookup_ioctx(ctx_id);
2196  	long ret = -EINVAL;
2197  
2198  	if (likely(ioctx)) {
2199  		if (likely(min_nr <= nr && min_nr >= 0))
2200  			ret = read_events(ioctx, min_nr, nr, events, until);
2201  		percpu_ref_put(&ioctx->users);
2202  	}
2203  
2204  	return ret;
2205  }
2206  
2207  /* io_getevents:
2208   *	Attempts to read at least min_nr events and up to nr events from
2209   *	the completion queue for the aio_context specified by ctx_id. If
2210   *	it succeeds, the number of read events is returned. May fail with
2211   *	-EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2212   *	out of range, if timeout is out of range.  May fail with -EFAULT
2213   *	if any of the memory specified is invalid.  May return 0 or
2214   *	< min_nr if the timeout specified by timeout has elapsed
2215   *	before sufficient events are available, where timeout == NULL
2216   *	specifies an infinite timeout. Note that the timeout pointed to by
2217   *	timeout is relative.  Will fail with -ENOSYS if not implemented.
2218   */
2219  #ifdef CONFIG_64BIT
2220  
2221  SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2222  		long, min_nr,
2223  		long, nr,
2224  		struct io_event __user *, events,
2225  		struct __kernel_timespec __user *, timeout)
2226  {
2227  	struct timespec64	ts;
2228  	int			ret;
2229  
2230  	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2231  		return -EFAULT;
2232  
2233  	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2234  	if (!ret && signal_pending(current))
2235  		ret = -EINTR;
2236  	return ret;
2237  }
2238  
2239  #endif
2240  
2241  struct __aio_sigset {
2242  	const sigset_t __user	*sigmask;
2243  	size_t		sigsetsize;
2244  };
2245  
2246  SYSCALL_DEFINE6(io_pgetevents,
2247  		aio_context_t, ctx_id,
2248  		long, min_nr,
2249  		long, nr,
2250  		struct io_event __user *, events,
2251  		struct __kernel_timespec __user *, timeout,
2252  		const struct __aio_sigset __user *, usig)
2253  {
2254  	struct __aio_sigset	ksig = { NULL, };
2255  	struct timespec64	ts;
2256  	bool interrupted;
2257  	int ret;
2258  
2259  	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2260  		return -EFAULT;
2261  
2262  	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2263  		return -EFAULT;
2264  
2265  	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2266  	if (ret)
2267  		return ret;
2268  
2269  	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2270  
2271  	interrupted = signal_pending(current);
2272  	restore_saved_sigmask_unless(interrupted);
2273  	if (interrupted && !ret)
2274  		ret = -ERESTARTNOHAND;
2275  
2276  	return ret;
2277  }
2278  
2279  #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2280  
2281  SYSCALL_DEFINE6(io_pgetevents_time32,
2282  		aio_context_t, ctx_id,
2283  		long, min_nr,
2284  		long, nr,
2285  		struct io_event __user *, events,
2286  		struct old_timespec32 __user *, timeout,
2287  		const struct __aio_sigset __user *, usig)
2288  {
2289  	struct __aio_sigset	ksig = { NULL, };
2290  	struct timespec64	ts;
2291  	bool interrupted;
2292  	int ret;
2293  
2294  	if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2295  		return -EFAULT;
2296  
2297  	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2298  		return -EFAULT;
2299  
2300  
2301  	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2302  	if (ret)
2303  		return ret;
2304  
2305  	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2306  
2307  	interrupted = signal_pending(current);
2308  	restore_saved_sigmask_unless(interrupted);
2309  	if (interrupted && !ret)
2310  		ret = -ERESTARTNOHAND;
2311  
2312  	return ret;
2313  }
2314  
2315  #endif
2316  
2317  #if defined(CONFIG_COMPAT_32BIT_TIME)
2318  
2319  SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2320  		__s32, min_nr,
2321  		__s32, nr,
2322  		struct io_event __user *, events,
2323  		struct old_timespec32 __user *, timeout)
2324  {
2325  	struct timespec64 t;
2326  	int ret;
2327  
2328  	if (timeout && get_old_timespec32(&t, timeout))
2329  		return -EFAULT;
2330  
2331  	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2332  	if (!ret && signal_pending(current))
2333  		ret = -EINTR;
2334  	return ret;
2335  }
2336  
2337  #endif
2338  
2339  #ifdef CONFIG_COMPAT
2340  
2341  struct __compat_aio_sigset {
2342  	compat_uptr_t		sigmask;
2343  	compat_size_t		sigsetsize;
2344  };
2345  
2346  #if defined(CONFIG_COMPAT_32BIT_TIME)
2347  
2348  COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2349  		compat_aio_context_t, ctx_id,
2350  		compat_long_t, min_nr,
2351  		compat_long_t, nr,
2352  		struct io_event __user *, events,
2353  		struct old_timespec32 __user *, timeout,
2354  		const struct __compat_aio_sigset __user *, usig)
2355  {
2356  	struct __compat_aio_sigset ksig = { 0, };
2357  	struct timespec64 t;
2358  	bool interrupted;
2359  	int ret;
2360  
2361  	if (timeout && get_old_timespec32(&t, timeout))
2362  		return -EFAULT;
2363  
2364  	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2365  		return -EFAULT;
2366  
2367  	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2368  	if (ret)
2369  		return ret;
2370  
2371  	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2372  
2373  	interrupted = signal_pending(current);
2374  	restore_saved_sigmask_unless(interrupted);
2375  	if (interrupted && !ret)
2376  		ret = -ERESTARTNOHAND;
2377  
2378  	return ret;
2379  }
2380  
2381  #endif
2382  
2383  COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2384  		compat_aio_context_t, ctx_id,
2385  		compat_long_t, min_nr,
2386  		compat_long_t, nr,
2387  		struct io_event __user *, events,
2388  		struct __kernel_timespec __user *, timeout,
2389  		const struct __compat_aio_sigset __user *, usig)
2390  {
2391  	struct __compat_aio_sigset ksig = { 0, };
2392  	struct timespec64 t;
2393  	bool interrupted;
2394  	int ret;
2395  
2396  	if (timeout && get_timespec64(&t, timeout))
2397  		return -EFAULT;
2398  
2399  	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2400  		return -EFAULT;
2401  
2402  	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2403  	if (ret)
2404  		return ret;
2405  
2406  	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2407  
2408  	interrupted = signal_pending(current);
2409  	restore_saved_sigmask_unless(interrupted);
2410  	if (interrupted && !ret)
2411  		ret = -ERESTARTNOHAND;
2412  
2413  	return ret;
2414  }
2415  #endif
2416