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 #include <linux/kernel.h> 12 #include <linux/init.h> 13 #include <linux/errno.h> 14 #include <linux/time.h> 15 #include <linux/aio_abi.h> 16 #include <linux/module.h> 17 #include <linux/syscalls.h> 18 19 #define DEBUG 0 20 21 #include <linux/sched.h> 22 #include <linux/fs.h> 23 #include <linux/file.h> 24 #include <linux/mm.h> 25 #include <linux/mman.h> 26 #include <linux/slab.h> 27 #include <linux/timer.h> 28 #include <linux/aio.h> 29 #include <linux/highmem.h> 30 #include <linux/workqueue.h> 31 #include <linux/security.h> 32 #include <linux/rcuref.h> 33 34 #include <asm/kmap_types.h> 35 #include <asm/uaccess.h> 36 #include <asm/mmu_context.h> 37 38 #if DEBUG > 1 39 #define dprintk printk 40 #else 41 #define dprintk(x...) do { ; } while (0) 42 #endif 43 44 /*------ sysctl variables----*/ 45 atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */ 46 unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 47 /*----end sysctl variables---*/ 48 49 static kmem_cache_t *kiocb_cachep; 50 static kmem_cache_t *kioctx_cachep; 51 52 static struct workqueue_struct *aio_wq; 53 54 /* Used for rare fput completion. */ 55 static void aio_fput_routine(void *); 56 static DECLARE_WORK(fput_work, aio_fput_routine, NULL); 57 58 static DEFINE_SPINLOCK(fput_lock); 59 static LIST_HEAD(fput_head); 60 61 static void aio_kick_handler(void *); 62 static void aio_queue_work(struct kioctx *); 63 64 /* aio_setup 65 * Creates the slab caches used by the aio routines, panic on 66 * failure as this is done early during the boot sequence. 67 */ 68 static int __init aio_setup(void) 69 { 70 kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb), 71 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 72 kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx), 73 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 74 75 aio_wq = create_workqueue("aio"); 76 77 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); 78 79 return 0; 80 } 81 82 static void aio_free_ring(struct kioctx *ctx) 83 { 84 struct aio_ring_info *info = &ctx->ring_info; 85 long i; 86 87 for (i=0; i<info->nr_pages; i++) 88 put_page(info->ring_pages[i]); 89 90 if (info->mmap_size) { 91 down_write(&ctx->mm->mmap_sem); 92 do_munmap(ctx->mm, info->mmap_base, info->mmap_size); 93 up_write(&ctx->mm->mmap_sem); 94 } 95 96 if (info->ring_pages && info->ring_pages != info->internal_pages) 97 kfree(info->ring_pages); 98 info->ring_pages = NULL; 99 info->nr = 0; 100 } 101 102 static int aio_setup_ring(struct kioctx *ctx) 103 { 104 struct aio_ring *ring; 105 struct aio_ring_info *info = &ctx->ring_info; 106 unsigned nr_events = ctx->max_reqs; 107 unsigned long size; 108 int nr_pages; 109 110 /* Compensate for the ring buffer's head/tail overlap entry */ 111 nr_events += 2; /* 1 is required, 2 for good luck */ 112 113 size = sizeof(struct aio_ring); 114 size += sizeof(struct io_event) * nr_events; 115 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; 116 117 if (nr_pages < 0) 118 return -EINVAL; 119 120 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); 121 122 info->nr = 0; 123 info->ring_pages = info->internal_pages; 124 if (nr_pages > AIO_RING_PAGES) { 125 info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL); 126 if (!info->ring_pages) 127 return -ENOMEM; 128 memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages); 129 } 130 131 info->mmap_size = nr_pages * PAGE_SIZE; 132 dprintk("attempting mmap of %lu bytes\n", info->mmap_size); 133 down_write(&ctx->mm->mmap_sem); 134 info->mmap_base = do_mmap(NULL, 0, info->mmap_size, 135 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 136 0); 137 if (IS_ERR((void *)info->mmap_base)) { 138 up_write(&ctx->mm->mmap_sem); 139 printk("mmap err: %ld\n", -info->mmap_base); 140 info->mmap_size = 0; 141 aio_free_ring(ctx); 142 return -EAGAIN; 143 } 144 145 dprintk("mmap address: 0x%08lx\n", info->mmap_base); 146 info->nr_pages = get_user_pages(current, ctx->mm, 147 info->mmap_base, nr_pages, 148 1, 0, info->ring_pages, NULL); 149 up_write(&ctx->mm->mmap_sem); 150 151 if (unlikely(info->nr_pages != nr_pages)) { 152 aio_free_ring(ctx); 153 return -EAGAIN; 154 } 155 156 ctx->user_id = info->mmap_base; 157 158 info->nr = nr_events; /* trusted copy */ 159 160 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 161 ring->nr = nr_events; /* user copy */ 162 ring->id = ctx->user_id; 163 ring->head = ring->tail = 0; 164 ring->magic = AIO_RING_MAGIC; 165 ring->compat_features = AIO_RING_COMPAT_FEATURES; 166 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; 167 ring->header_length = sizeof(struct aio_ring); 168 kunmap_atomic(ring, KM_USER0); 169 170 return 0; 171 } 172 173 174 /* aio_ring_event: returns a pointer to the event at the given index from 175 * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); 176 */ 177 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) 178 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) 179 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) 180 181 #define aio_ring_event(info, nr, km) ({ \ 182 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ 183 struct io_event *__event; \ 184 __event = kmap_atomic( \ 185 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ 186 __event += pos % AIO_EVENTS_PER_PAGE; \ 187 __event; \ 188 }) 189 190 #define put_aio_ring_event(event, km) do { \ 191 struct io_event *__event = (event); \ 192 (void)__event; \ 193 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ 194 } while(0) 195 196 /* ioctx_alloc 197 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. 198 */ 199 static struct kioctx *ioctx_alloc(unsigned nr_events) 200 { 201 struct mm_struct *mm; 202 struct kioctx *ctx; 203 204 /* Prevent overflows */ 205 if ((nr_events > (0x10000000U / sizeof(struct io_event))) || 206 (nr_events > (0x10000000U / sizeof(struct kiocb)))) { 207 pr_debug("ENOMEM: nr_events too high\n"); 208 return ERR_PTR(-EINVAL); 209 } 210 211 if (nr_events > aio_max_nr) 212 return ERR_PTR(-EAGAIN); 213 214 ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL); 215 if (!ctx) 216 return ERR_PTR(-ENOMEM); 217 218 memset(ctx, 0, sizeof(*ctx)); 219 ctx->max_reqs = nr_events; 220 mm = ctx->mm = current->mm; 221 atomic_inc(&mm->mm_count); 222 223 atomic_set(&ctx->users, 1); 224 spin_lock_init(&ctx->ctx_lock); 225 spin_lock_init(&ctx->ring_info.ring_lock); 226 init_waitqueue_head(&ctx->wait); 227 228 INIT_LIST_HEAD(&ctx->active_reqs); 229 INIT_LIST_HEAD(&ctx->run_list); 230 INIT_WORK(&ctx->wq, aio_kick_handler, ctx); 231 232 if (aio_setup_ring(ctx) < 0) 233 goto out_freectx; 234 235 /* limit the number of system wide aios */ 236 atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */ 237 if (unlikely(atomic_read(&aio_nr) > aio_max_nr)) 238 goto out_cleanup; 239 240 /* now link into global list. kludge. FIXME */ 241 write_lock(&mm->ioctx_list_lock); 242 ctx->next = mm->ioctx_list; 243 mm->ioctx_list = ctx; 244 write_unlock(&mm->ioctx_list_lock); 245 246 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 247 ctx, ctx->user_id, current->mm, ctx->ring_info.nr); 248 return ctx; 249 250 out_cleanup: 251 atomic_sub(ctx->max_reqs, &aio_nr); 252 ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */ 253 __put_ioctx(ctx); 254 return ERR_PTR(-EAGAIN); 255 256 out_freectx: 257 mmdrop(mm); 258 kmem_cache_free(kioctx_cachep, ctx); 259 ctx = ERR_PTR(-ENOMEM); 260 261 dprintk("aio: error allocating ioctx %p\n", ctx); 262 return ctx; 263 } 264 265 /* aio_cancel_all 266 * Cancels all outstanding aio requests on an aio context. Used 267 * when the processes owning a context have all exited to encourage 268 * the rapid destruction of the kioctx. 269 */ 270 static void aio_cancel_all(struct kioctx *ctx) 271 { 272 int (*cancel)(struct kiocb *, struct io_event *); 273 struct io_event res; 274 spin_lock_irq(&ctx->ctx_lock); 275 ctx->dead = 1; 276 while (!list_empty(&ctx->active_reqs)) { 277 struct list_head *pos = ctx->active_reqs.next; 278 struct kiocb *iocb = list_kiocb(pos); 279 list_del_init(&iocb->ki_list); 280 cancel = iocb->ki_cancel; 281 kiocbSetCancelled(iocb); 282 if (cancel) { 283 iocb->ki_users++; 284 spin_unlock_irq(&ctx->ctx_lock); 285 cancel(iocb, &res); 286 spin_lock_irq(&ctx->ctx_lock); 287 } 288 } 289 spin_unlock_irq(&ctx->ctx_lock); 290 } 291 292 static void wait_for_all_aios(struct kioctx *ctx) 293 { 294 struct task_struct *tsk = current; 295 DECLARE_WAITQUEUE(wait, tsk); 296 297 if (!ctx->reqs_active) 298 return; 299 300 add_wait_queue(&ctx->wait, &wait); 301 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 302 while (ctx->reqs_active) { 303 schedule(); 304 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 305 } 306 __set_task_state(tsk, TASK_RUNNING); 307 remove_wait_queue(&ctx->wait, &wait); 308 } 309 310 /* wait_on_sync_kiocb: 311 * Waits on the given sync kiocb to complete. 312 */ 313 ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) 314 { 315 while (iocb->ki_users) { 316 set_current_state(TASK_UNINTERRUPTIBLE); 317 if (!iocb->ki_users) 318 break; 319 schedule(); 320 } 321 __set_current_state(TASK_RUNNING); 322 return iocb->ki_user_data; 323 } 324 325 /* exit_aio: called when the last user of mm goes away. At this point, 326 * there is no way for any new requests to be submited or any of the 327 * io_* syscalls to be called on the context. However, there may be 328 * outstanding requests which hold references to the context; as they 329 * go away, they will call put_ioctx and release any pinned memory 330 * associated with the request (held via struct page * references). 331 */ 332 void fastcall exit_aio(struct mm_struct *mm) 333 { 334 struct kioctx *ctx = mm->ioctx_list; 335 mm->ioctx_list = NULL; 336 while (ctx) { 337 struct kioctx *next = ctx->next; 338 ctx->next = NULL; 339 aio_cancel_all(ctx); 340 341 wait_for_all_aios(ctx); 342 /* 343 * this is an overkill, but ensures we don't leave 344 * the ctx on the aio_wq 345 */ 346 flush_workqueue(aio_wq); 347 348 if (1 != atomic_read(&ctx->users)) 349 printk(KERN_DEBUG 350 "exit_aio:ioctx still alive: %d %d %d\n", 351 atomic_read(&ctx->users), ctx->dead, 352 ctx->reqs_active); 353 put_ioctx(ctx); 354 ctx = next; 355 } 356 } 357 358 /* __put_ioctx 359 * Called when the last user of an aio context has gone away, 360 * and the struct needs to be freed. 361 */ 362 void fastcall __put_ioctx(struct kioctx *ctx) 363 { 364 unsigned nr_events = ctx->max_reqs; 365 366 if (unlikely(ctx->reqs_active)) 367 BUG(); 368 369 cancel_delayed_work(&ctx->wq); 370 flush_workqueue(aio_wq); 371 aio_free_ring(ctx); 372 mmdrop(ctx->mm); 373 ctx->mm = NULL; 374 pr_debug("__put_ioctx: freeing %p\n", ctx); 375 kmem_cache_free(kioctx_cachep, ctx); 376 377 atomic_sub(nr_events, &aio_nr); 378 } 379 380 /* aio_get_req 381 * Allocate a slot for an aio request. Increments the users count 382 * of the kioctx so that the kioctx stays around until all requests are 383 * complete. Returns NULL if no requests are free. 384 * 385 * Returns with kiocb->users set to 2. The io submit code path holds 386 * an extra reference while submitting the i/o. 387 * This prevents races between the aio code path referencing the 388 * req (after submitting it) and aio_complete() freeing the req. 389 */ 390 static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); 391 static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) 392 { 393 struct kiocb *req = NULL; 394 struct aio_ring *ring; 395 int okay = 0; 396 397 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); 398 if (unlikely(!req)) 399 return NULL; 400 401 req->ki_flags = 1 << KIF_LOCKED; 402 req->ki_users = 2; 403 req->ki_key = 0; 404 req->ki_ctx = ctx; 405 req->ki_cancel = NULL; 406 req->ki_retry = NULL; 407 req->ki_dtor = NULL; 408 req->private = NULL; 409 INIT_LIST_HEAD(&req->ki_run_list); 410 411 /* Check if the completion queue has enough free space to 412 * accept an event from this io. 413 */ 414 spin_lock_irq(&ctx->ctx_lock); 415 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); 416 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { 417 list_add(&req->ki_list, &ctx->active_reqs); 418 get_ioctx(ctx); 419 ctx->reqs_active++; 420 okay = 1; 421 } 422 kunmap_atomic(ring, KM_USER0); 423 spin_unlock_irq(&ctx->ctx_lock); 424 425 if (!okay) { 426 kmem_cache_free(kiocb_cachep, req); 427 req = NULL; 428 } 429 430 return req; 431 } 432 433 static inline struct kiocb *aio_get_req(struct kioctx *ctx) 434 { 435 struct kiocb *req; 436 /* Handle a potential starvation case -- should be exceedingly rare as 437 * requests will be stuck on fput_head only if the aio_fput_routine is 438 * delayed and the requests were the last user of the struct file. 439 */ 440 req = __aio_get_req(ctx); 441 if (unlikely(NULL == req)) { 442 aio_fput_routine(NULL); 443 req = __aio_get_req(ctx); 444 } 445 return req; 446 } 447 448 static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) 449 { 450 if (req->ki_dtor) 451 req->ki_dtor(req); 452 kmem_cache_free(kiocb_cachep, req); 453 ctx->reqs_active--; 454 455 if (unlikely(!ctx->reqs_active && ctx->dead)) 456 wake_up(&ctx->wait); 457 } 458 459 static void aio_fput_routine(void *data) 460 { 461 spin_lock_irq(&fput_lock); 462 while (likely(!list_empty(&fput_head))) { 463 struct kiocb *req = list_kiocb(fput_head.next); 464 struct kioctx *ctx = req->ki_ctx; 465 466 list_del(&req->ki_list); 467 spin_unlock_irq(&fput_lock); 468 469 /* Complete the fput */ 470 __fput(req->ki_filp); 471 472 /* Link the iocb into the context's free list */ 473 spin_lock_irq(&ctx->ctx_lock); 474 really_put_req(ctx, req); 475 spin_unlock_irq(&ctx->ctx_lock); 476 477 put_ioctx(ctx); 478 spin_lock_irq(&fput_lock); 479 } 480 spin_unlock_irq(&fput_lock); 481 } 482 483 /* __aio_put_req 484 * Returns true if this put was the last user of the request. 485 */ 486 static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) 487 { 488 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", 489 req, atomic_read(&req->ki_filp->f_count)); 490 491 req->ki_users --; 492 if (unlikely(req->ki_users < 0)) 493 BUG(); 494 if (likely(req->ki_users)) 495 return 0; 496 list_del(&req->ki_list); /* remove from active_reqs */ 497 req->ki_cancel = NULL; 498 req->ki_retry = NULL; 499 500 /* Must be done under the lock to serialise against cancellation. 501 * Call this aio_fput as it duplicates fput via the fput_work. 502 */ 503 if (unlikely(rcuref_dec_and_test(&req->ki_filp->f_count))) { 504 get_ioctx(ctx); 505 spin_lock(&fput_lock); 506 list_add(&req->ki_list, &fput_head); 507 spin_unlock(&fput_lock); 508 queue_work(aio_wq, &fput_work); 509 } else 510 really_put_req(ctx, req); 511 return 1; 512 } 513 514 /* aio_put_req 515 * Returns true if this put was the last user of the kiocb, 516 * false if the request is still in use. 517 */ 518 int fastcall aio_put_req(struct kiocb *req) 519 { 520 struct kioctx *ctx = req->ki_ctx; 521 int ret; 522 spin_lock_irq(&ctx->ctx_lock); 523 ret = __aio_put_req(ctx, req); 524 spin_unlock_irq(&ctx->ctx_lock); 525 if (ret) 526 put_ioctx(ctx); 527 return ret; 528 } 529 530 /* Lookup an ioctx id. ioctx_list is lockless for reads. 531 * FIXME: this is O(n) and is only suitable for development. 532 */ 533 struct kioctx *lookup_ioctx(unsigned long ctx_id) 534 { 535 struct kioctx *ioctx; 536 struct mm_struct *mm; 537 538 mm = current->mm; 539 read_lock(&mm->ioctx_list_lock); 540 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) 541 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { 542 get_ioctx(ioctx); 543 break; 544 } 545 read_unlock(&mm->ioctx_list_lock); 546 547 return ioctx; 548 } 549 550 static int lock_kiocb_action(void *param) 551 { 552 schedule(); 553 return 0; 554 } 555 556 static inline void lock_kiocb(struct kiocb *iocb) 557 { 558 wait_on_bit_lock(&iocb->ki_flags, KIF_LOCKED, lock_kiocb_action, 559 TASK_UNINTERRUPTIBLE); 560 } 561 562 static inline void unlock_kiocb(struct kiocb *iocb) 563 { 564 kiocbClearLocked(iocb); 565 smp_mb__after_clear_bit(); 566 wake_up_bit(&iocb->ki_flags, KIF_LOCKED); 567 } 568 569 /* 570 * use_mm 571 * Makes the calling kernel thread take on the specified 572 * mm context. 573 * Called by the retry thread execute retries within the 574 * iocb issuer's mm context, so that copy_from/to_user 575 * operations work seamlessly for aio. 576 * (Note: this routine is intended to be called only 577 * from a kernel thread context) 578 */ 579 static void use_mm(struct mm_struct *mm) 580 { 581 struct mm_struct *active_mm; 582 struct task_struct *tsk = current; 583 584 task_lock(tsk); 585 tsk->flags |= PF_BORROWED_MM; 586 active_mm = tsk->active_mm; 587 atomic_inc(&mm->mm_count); 588 tsk->mm = mm; 589 tsk->active_mm = mm; 590 /* 591 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise 592 * it won't work. Update it accordingly if you change it here 593 */ 594 activate_mm(active_mm, mm); 595 task_unlock(tsk); 596 597 mmdrop(active_mm); 598 } 599 600 /* 601 * unuse_mm 602 * Reverses the effect of use_mm, i.e. releases the 603 * specified mm context which was earlier taken on 604 * by the calling kernel thread 605 * (Note: this routine is intended to be called only 606 * from a kernel thread context) 607 * 608 * Comments: Called with ctx->ctx_lock held. This nests 609 * task_lock instead ctx_lock. 610 */ 611 static void unuse_mm(struct mm_struct *mm) 612 { 613 struct task_struct *tsk = current; 614 615 task_lock(tsk); 616 tsk->flags &= ~PF_BORROWED_MM; 617 tsk->mm = NULL; 618 /* active_mm is still 'mm' */ 619 enter_lazy_tlb(mm, tsk); 620 task_unlock(tsk); 621 } 622 623 /* 624 * Queue up a kiocb to be retried. Assumes that the kiocb 625 * has already been marked as kicked, and places it on 626 * the retry run list for the corresponding ioctx, if it 627 * isn't already queued. Returns 1 if it actually queued 628 * the kiocb (to tell the caller to activate the work 629 * queue to process it), or 0, if it found that it was 630 * already queued. 631 * 632 * Should be called with the spin lock iocb->ki_ctx->ctx_lock 633 * held 634 */ 635 static inline int __queue_kicked_iocb(struct kiocb *iocb) 636 { 637 struct kioctx *ctx = iocb->ki_ctx; 638 639 if (list_empty(&iocb->ki_run_list)) { 640 list_add_tail(&iocb->ki_run_list, 641 &ctx->run_list); 642 return 1; 643 } 644 return 0; 645 } 646 647 /* aio_run_iocb 648 * This is the core aio execution routine. It is 649 * invoked both for initial i/o submission and 650 * subsequent retries via the aio_kick_handler. 651 * Expects to be invoked with iocb->ki_ctx->lock 652 * already held. The lock is released and reaquired 653 * as needed during processing. 654 * 655 * Calls the iocb retry method (already setup for the 656 * iocb on initial submission) for operation specific 657 * handling, but takes care of most of common retry 658 * execution details for a given iocb. The retry method 659 * needs to be non-blocking as far as possible, to avoid 660 * holding up other iocbs waiting to be serviced by the 661 * retry kernel thread. 662 * 663 * The trickier parts in this code have to do with 664 * ensuring that only one retry instance is in progress 665 * for a given iocb at any time. Providing that guarantee 666 * simplifies the coding of individual aio operations as 667 * it avoids various potential races. 668 */ 669 static ssize_t aio_run_iocb(struct kiocb *iocb) 670 { 671 struct kioctx *ctx = iocb->ki_ctx; 672 ssize_t (*retry)(struct kiocb *); 673 ssize_t ret; 674 675 if (iocb->ki_retried++ > 1024*1024) { 676 printk("Maximal retry count. Bytes done %Zd\n", 677 iocb->ki_nbytes - iocb->ki_left); 678 return -EAGAIN; 679 } 680 681 if (!(iocb->ki_retried & 0xff)) { 682 pr_debug("%ld retry: %d of %d\n", iocb->ki_retried, 683 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 684 } 685 686 if (!(retry = iocb->ki_retry)) { 687 printk("aio_run_iocb: iocb->ki_retry = NULL\n"); 688 return 0; 689 } 690 691 /* 692 * We don't want the next retry iteration for this 693 * operation to start until this one has returned and 694 * updated the iocb state. However, wait_queue functions 695 * can trigger a kick_iocb from interrupt context in the 696 * meantime, indicating that data is available for the next 697 * iteration. We want to remember that and enable the 698 * next retry iteration _after_ we are through with 699 * this one. 700 * 701 * So, in order to be able to register a "kick", but 702 * prevent it from being queued now, we clear the kick 703 * flag, but make the kick code *think* that the iocb is 704 * still on the run list until we are actually done. 705 * When we are done with this iteration, we check if 706 * the iocb was kicked in the meantime and if so, queue 707 * it up afresh. 708 */ 709 710 kiocbClearKicked(iocb); 711 712 /* 713 * This is so that aio_complete knows it doesn't need to 714 * pull the iocb off the run list (We can't just call 715 * INIT_LIST_HEAD because we don't want a kick_iocb to 716 * queue this on the run list yet) 717 */ 718 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; 719 spin_unlock_irq(&ctx->ctx_lock); 720 721 /* Quit retrying if the i/o has been cancelled */ 722 if (kiocbIsCancelled(iocb)) { 723 ret = -EINTR; 724 aio_complete(iocb, ret, 0); 725 /* must not access the iocb after this */ 726 goto out; 727 } 728 729 /* 730 * Now we are all set to call the retry method in async 731 * context. By setting this thread's io_wait context 732 * to point to the wait queue entry inside the currently 733 * running iocb for the duration of the retry, we ensure 734 * that async notification wakeups are queued by the 735 * operation instead of blocking waits, and when notified, 736 * cause the iocb to be kicked for continuation (through 737 * the aio_wake_function callback). 738 */ 739 BUG_ON(current->io_wait != NULL); 740 current->io_wait = &iocb->ki_wait; 741 ret = retry(iocb); 742 current->io_wait = NULL; 743 744 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) { 745 BUG_ON(!list_empty(&iocb->ki_wait.task_list)); 746 aio_complete(iocb, ret, 0); 747 } 748 out: 749 spin_lock_irq(&ctx->ctx_lock); 750 751 if (-EIOCBRETRY == ret) { 752 /* 753 * OK, now that we are done with this iteration 754 * and know that there is more left to go, 755 * this is where we let go so that a subsequent 756 * "kick" can start the next iteration 757 */ 758 759 /* will make __queue_kicked_iocb succeed from here on */ 760 INIT_LIST_HEAD(&iocb->ki_run_list); 761 /* we must queue the next iteration ourselves, if it 762 * has already been kicked */ 763 if (kiocbIsKicked(iocb)) { 764 __queue_kicked_iocb(iocb); 765 766 /* 767 * __queue_kicked_iocb will always return 1 here, because 768 * iocb->ki_run_list is empty at this point so it should 769 * be safe to unconditionally queue the context into the 770 * work queue. 771 */ 772 aio_queue_work(ctx); 773 } 774 } 775 return ret; 776 } 777 778 /* 779 * __aio_run_iocbs: 780 * Process all pending retries queued on the ioctx 781 * run list. 782 * Assumes it is operating within the aio issuer's mm 783 * context. Expects to be called with ctx->ctx_lock held 784 */ 785 static int __aio_run_iocbs(struct kioctx *ctx) 786 { 787 struct kiocb *iocb; 788 LIST_HEAD(run_list); 789 790 list_splice_init(&ctx->run_list, &run_list); 791 while (!list_empty(&run_list)) { 792 iocb = list_entry(run_list.next, struct kiocb, 793 ki_run_list); 794 list_del(&iocb->ki_run_list); 795 /* 796 * Hold an extra reference while retrying i/o. 797 */ 798 iocb->ki_users++; /* grab extra reference */ 799 lock_kiocb(iocb); 800 aio_run_iocb(iocb); 801 unlock_kiocb(iocb); 802 if (__aio_put_req(ctx, iocb)) /* drop extra ref */ 803 put_ioctx(ctx); 804 } 805 if (!list_empty(&ctx->run_list)) 806 return 1; 807 return 0; 808 } 809 810 static void aio_queue_work(struct kioctx * ctx) 811 { 812 unsigned long timeout; 813 /* 814 * if someone is waiting, get the work started right 815 * away, otherwise, use a longer delay 816 */ 817 smp_mb(); 818 if (waitqueue_active(&ctx->wait)) 819 timeout = 1; 820 else 821 timeout = HZ/10; 822 queue_delayed_work(aio_wq, &ctx->wq, timeout); 823 } 824 825 826 /* 827 * aio_run_iocbs: 828 * Process all pending retries queued on the ioctx 829 * run list. 830 * Assumes it is operating within the aio issuer's mm 831 * context. 832 */ 833 static inline void aio_run_iocbs(struct kioctx *ctx) 834 { 835 int requeue; 836 837 spin_lock_irq(&ctx->ctx_lock); 838 839 requeue = __aio_run_iocbs(ctx); 840 spin_unlock_irq(&ctx->ctx_lock); 841 if (requeue) 842 aio_queue_work(ctx); 843 } 844 845 /* 846 * just like aio_run_iocbs, but keeps running them until 847 * the list stays empty 848 */ 849 static inline void aio_run_all_iocbs(struct kioctx *ctx) 850 { 851 spin_lock_irq(&ctx->ctx_lock); 852 while (__aio_run_iocbs(ctx)) 853 ; 854 spin_unlock_irq(&ctx->ctx_lock); 855 } 856 857 /* 858 * aio_kick_handler: 859 * Work queue handler triggered to process pending 860 * retries on an ioctx. Takes on the aio issuer's 861 * mm context before running the iocbs, so that 862 * copy_xxx_user operates on the issuer's address 863 * space. 864 * Run on aiod's context. 865 */ 866 static void aio_kick_handler(void *data) 867 { 868 struct kioctx *ctx = data; 869 mm_segment_t oldfs = get_fs(); 870 int requeue; 871 872 set_fs(USER_DS); 873 use_mm(ctx->mm); 874 spin_lock_irq(&ctx->ctx_lock); 875 requeue =__aio_run_iocbs(ctx); 876 unuse_mm(ctx->mm); 877 spin_unlock_irq(&ctx->ctx_lock); 878 set_fs(oldfs); 879 /* 880 * we're in a worker thread already, don't use queue_delayed_work, 881 */ 882 if (requeue) 883 queue_work(aio_wq, &ctx->wq); 884 } 885 886 887 /* 888 * Called by kick_iocb to queue the kiocb for retry 889 * and if required activate the aio work queue to process 890 * it 891 */ 892 static void try_queue_kicked_iocb(struct kiocb *iocb) 893 { 894 struct kioctx *ctx = iocb->ki_ctx; 895 unsigned long flags; 896 int run = 0; 897 898 /* We're supposed to be the only path putting the iocb back on the run 899 * list. If we find that the iocb is *back* on a wait queue already 900 * than retry has happened before we could queue the iocb. This also 901 * means that the retry could have completed and freed our iocb, no 902 * good. */ 903 BUG_ON((!list_empty(&iocb->ki_wait.task_list))); 904 905 spin_lock_irqsave(&ctx->ctx_lock, flags); 906 /* set this inside the lock so that we can't race with aio_run_iocb() 907 * testing it and putting the iocb on the run list under the lock */ 908 if (!kiocbTryKick(iocb)) 909 run = __queue_kicked_iocb(iocb); 910 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 911 if (run) 912 aio_queue_work(ctx); 913 } 914 915 /* 916 * kick_iocb: 917 * Called typically from a wait queue callback context 918 * (aio_wake_function) to trigger a retry of the iocb. 919 * The retry is usually executed by aio workqueue 920 * threads (See aio_kick_handler). 921 */ 922 void fastcall kick_iocb(struct kiocb *iocb) 923 { 924 /* sync iocbs are easy: they can only ever be executing from a 925 * single context. */ 926 if (is_sync_kiocb(iocb)) { 927 kiocbSetKicked(iocb); 928 wake_up_process(iocb->ki_obj.tsk); 929 return; 930 } 931 932 try_queue_kicked_iocb(iocb); 933 } 934 EXPORT_SYMBOL(kick_iocb); 935 936 /* aio_complete 937 * Called when the io request on the given iocb is complete. 938 * Returns true if this is the last user of the request. The 939 * only other user of the request can be the cancellation code. 940 */ 941 int fastcall aio_complete(struct kiocb *iocb, long res, long res2) 942 { 943 struct kioctx *ctx = iocb->ki_ctx; 944 struct aio_ring_info *info; 945 struct aio_ring *ring; 946 struct io_event *event; 947 unsigned long flags; 948 unsigned long tail; 949 int ret; 950 951 /* Special case handling for sync iocbs: events go directly 952 * into the iocb for fast handling. Note that this will not 953 * work if we allow sync kiocbs to be cancelled. in which 954 * case the usage count checks will have to move under ctx_lock 955 * for all cases. 956 */ 957 if (is_sync_kiocb(iocb)) { 958 int ret; 959 960 iocb->ki_user_data = res; 961 if (iocb->ki_users == 1) { 962 iocb->ki_users = 0; 963 ret = 1; 964 } else { 965 spin_lock_irq(&ctx->ctx_lock); 966 iocb->ki_users--; 967 ret = (0 == iocb->ki_users); 968 spin_unlock_irq(&ctx->ctx_lock); 969 } 970 /* sync iocbs put the task here for us */ 971 wake_up_process(iocb->ki_obj.tsk); 972 return ret; 973 } 974 975 info = &ctx->ring_info; 976 977 /* add a completion event to the ring buffer. 978 * must be done holding ctx->ctx_lock to prevent 979 * other code from messing with the tail 980 * pointer since we might be called from irq 981 * context. 982 */ 983 spin_lock_irqsave(&ctx->ctx_lock, flags); 984 985 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) 986 list_del_init(&iocb->ki_run_list); 987 988 /* 989 * cancelled requests don't get events, userland was given one 990 * when the event got cancelled. 991 */ 992 if (kiocbIsCancelled(iocb)) 993 goto put_rq; 994 995 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); 996 997 tail = info->tail; 998 event = aio_ring_event(info, tail, KM_IRQ0); 999 if (++tail >= info->nr) 1000 tail = 0; 1001 1002 event->obj = (u64)(unsigned long)iocb->ki_obj.user; 1003 event->data = iocb->ki_user_data; 1004 event->res = res; 1005 event->res2 = res2; 1006 1007 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", 1008 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, 1009 res, res2); 1010 1011 /* after flagging the request as done, we 1012 * must never even look at it again 1013 */ 1014 smp_wmb(); /* make event visible before updating tail */ 1015 1016 info->tail = tail; 1017 ring->tail = tail; 1018 1019 put_aio_ring_event(event, KM_IRQ0); 1020 kunmap_atomic(ring, KM_IRQ1); 1021 1022 pr_debug("added to ring %p at [%lu]\n", iocb, tail); 1023 1024 pr_debug("%ld retries: %d of %d\n", iocb->ki_retried, 1025 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 1026 put_rq: 1027 /* everything turned out well, dispose of the aiocb. */ 1028 ret = __aio_put_req(ctx, iocb); 1029 1030 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 1031 1032 if (waitqueue_active(&ctx->wait)) 1033 wake_up(&ctx->wait); 1034 1035 if (ret) 1036 put_ioctx(ctx); 1037 1038 return ret; 1039 } 1040 1041 /* aio_read_evt 1042 * Pull an event off of the ioctx's event ring. Returns the number of 1043 * events fetched (0 or 1 ;-) 1044 * FIXME: make this use cmpxchg. 1045 * TODO: make the ringbuffer user mmap()able (requires FIXME). 1046 */ 1047 static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) 1048 { 1049 struct aio_ring_info *info = &ioctx->ring_info; 1050 struct aio_ring *ring; 1051 unsigned long head; 1052 int ret = 0; 1053 1054 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 1055 dprintk("in aio_read_evt h%lu t%lu m%lu\n", 1056 (unsigned long)ring->head, (unsigned long)ring->tail, 1057 (unsigned long)ring->nr); 1058 1059 if (ring->head == ring->tail) 1060 goto out; 1061 1062 spin_lock(&info->ring_lock); 1063 1064 head = ring->head % info->nr; 1065 if (head != ring->tail) { 1066 struct io_event *evp = aio_ring_event(info, head, KM_USER1); 1067 *ent = *evp; 1068 head = (head + 1) % info->nr; 1069 smp_mb(); /* finish reading the event before updatng the head */ 1070 ring->head = head; 1071 ret = 1; 1072 put_aio_ring_event(evp, KM_USER1); 1073 } 1074 spin_unlock(&info->ring_lock); 1075 1076 out: 1077 kunmap_atomic(ring, KM_USER0); 1078 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, 1079 (unsigned long)ring->head, (unsigned long)ring->tail); 1080 return ret; 1081 } 1082 1083 struct aio_timeout { 1084 struct timer_list timer; 1085 int timed_out; 1086 struct task_struct *p; 1087 }; 1088 1089 static void timeout_func(unsigned long data) 1090 { 1091 struct aio_timeout *to = (struct aio_timeout *)data; 1092 1093 to->timed_out = 1; 1094 wake_up_process(to->p); 1095 } 1096 1097 static inline void init_timeout(struct aio_timeout *to) 1098 { 1099 init_timer(&to->timer); 1100 to->timer.data = (unsigned long)to; 1101 to->timer.function = timeout_func; 1102 to->timed_out = 0; 1103 to->p = current; 1104 } 1105 1106 static inline void set_timeout(long start_jiffies, struct aio_timeout *to, 1107 const struct timespec *ts) 1108 { 1109 to->timer.expires = start_jiffies + timespec_to_jiffies(ts); 1110 if (time_after(to->timer.expires, jiffies)) 1111 add_timer(&to->timer); 1112 else 1113 to->timed_out = 1; 1114 } 1115 1116 static inline void clear_timeout(struct aio_timeout *to) 1117 { 1118 del_singleshot_timer_sync(&to->timer); 1119 } 1120 1121 static int read_events(struct kioctx *ctx, 1122 long min_nr, long nr, 1123 struct io_event __user *event, 1124 struct timespec __user *timeout) 1125 { 1126 long start_jiffies = jiffies; 1127 struct task_struct *tsk = current; 1128 DECLARE_WAITQUEUE(wait, tsk); 1129 int ret; 1130 int i = 0; 1131 struct io_event ent; 1132 struct aio_timeout to; 1133 int retry = 0; 1134 1135 /* needed to zero any padding within an entry (there shouldn't be 1136 * any, but C is fun! 1137 */ 1138 memset(&ent, 0, sizeof(ent)); 1139 retry: 1140 ret = 0; 1141 while (likely(i < nr)) { 1142 ret = aio_read_evt(ctx, &ent); 1143 if (unlikely(ret <= 0)) 1144 break; 1145 1146 dprintk("read event: %Lx %Lx %Lx %Lx\n", 1147 ent.data, ent.obj, ent.res, ent.res2); 1148 1149 /* Could we split the check in two? */ 1150 ret = -EFAULT; 1151 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1152 dprintk("aio: lost an event due to EFAULT.\n"); 1153 break; 1154 } 1155 ret = 0; 1156 1157 /* Good, event copied to userland, update counts. */ 1158 event ++; 1159 i ++; 1160 } 1161 1162 if (min_nr <= i) 1163 return i; 1164 if (ret) 1165 return ret; 1166 1167 /* End fast path */ 1168 1169 /* racey check, but it gets redone */ 1170 if (!retry && unlikely(!list_empty(&ctx->run_list))) { 1171 retry = 1; 1172 aio_run_all_iocbs(ctx); 1173 goto retry; 1174 } 1175 1176 init_timeout(&to); 1177 if (timeout) { 1178 struct timespec ts; 1179 ret = -EFAULT; 1180 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1181 goto out; 1182 1183 set_timeout(start_jiffies, &to, &ts); 1184 } 1185 1186 while (likely(i < nr)) { 1187 add_wait_queue_exclusive(&ctx->wait, &wait); 1188 do { 1189 set_task_state(tsk, TASK_INTERRUPTIBLE); 1190 ret = aio_read_evt(ctx, &ent); 1191 if (ret) 1192 break; 1193 if (min_nr <= i) 1194 break; 1195 ret = 0; 1196 if (to.timed_out) /* Only check after read evt */ 1197 break; 1198 schedule(); 1199 if (signal_pending(tsk)) { 1200 ret = -EINTR; 1201 break; 1202 } 1203 /*ret = aio_read_evt(ctx, &ent);*/ 1204 } while (1) ; 1205 1206 set_task_state(tsk, TASK_RUNNING); 1207 remove_wait_queue(&ctx->wait, &wait); 1208 1209 if (unlikely(ret <= 0)) 1210 break; 1211 1212 ret = -EFAULT; 1213 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1214 dprintk("aio: lost an event due to EFAULT.\n"); 1215 break; 1216 } 1217 1218 /* Good, event copied to userland, update counts. */ 1219 event ++; 1220 i ++; 1221 } 1222 1223 if (timeout) 1224 clear_timeout(&to); 1225 out: 1226 return i ? i : ret; 1227 } 1228 1229 /* Take an ioctx and remove it from the list of ioctx's. Protects 1230 * against races with itself via ->dead. 1231 */ 1232 static void io_destroy(struct kioctx *ioctx) 1233 { 1234 struct mm_struct *mm = current->mm; 1235 struct kioctx **tmp; 1236 int was_dead; 1237 1238 /* delete the entry from the list is someone else hasn't already */ 1239 write_lock(&mm->ioctx_list_lock); 1240 was_dead = ioctx->dead; 1241 ioctx->dead = 1; 1242 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; 1243 tmp = &(*tmp)->next) 1244 ; 1245 if (*tmp) 1246 *tmp = ioctx->next; 1247 write_unlock(&mm->ioctx_list_lock); 1248 1249 dprintk("aio_release(%p)\n", ioctx); 1250 if (likely(!was_dead)) 1251 put_ioctx(ioctx); /* twice for the list */ 1252 1253 aio_cancel_all(ioctx); 1254 wait_for_all_aios(ioctx); 1255 put_ioctx(ioctx); /* once for the lookup */ 1256 } 1257 1258 /* sys_io_setup: 1259 * Create an aio_context capable of receiving at least nr_events. 1260 * ctxp must not point to an aio_context that already exists, and 1261 * must be initialized to 0 prior to the call. On successful 1262 * creation of the aio_context, *ctxp is filled in with the resulting 1263 * handle. May fail with -EINVAL if *ctxp is not initialized, 1264 * if the specified nr_events exceeds internal limits. May fail 1265 * with -EAGAIN if the specified nr_events exceeds the user's limit 1266 * of available events. May fail with -ENOMEM if insufficient kernel 1267 * resources are available. May fail with -EFAULT if an invalid 1268 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1269 * implemented. 1270 */ 1271 asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp) 1272 { 1273 struct kioctx *ioctx = NULL; 1274 unsigned long ctx; 1275 long ret; 1276 1277 ret = get_user(ctx, ctxp); 1278 if (unlikely(ret)) 1279 goto out; 1280 1281 ret = -EINVAL; 1282 if (unlikely(ctx || (int)nr_events <= 0)) { 1283 pr_debug("EINVAL: io_setup: ctx or nr_events > max\n"); 1284 goto out; 1285 } 1286 1287 ioctx = ioctx_alloc(nr_events); 1288 ret = PTR_ERR(ioctx); 1289 if (!IS_ERR(ioctx)) { 1290 ret = put_user(ioctx->user_id, ctxp); 1291 if (!ret) 1292 return 0; 1293 1294 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ 1295 io_destroy(ioctx); 1296 } 1297 1298 out: 1299 return ret; 1300 } 1301 1302 /* sys_io_destroy: 1303 * Destroy the aio_context specified. May cancel any outstanding 1304 * AIOs and block on completion. Will fail with -ENOSYS if not 1305 * implemented. May fail with -EFAULT if the context pointed to 1306 * is invalid. 1307 */ 1308 asmlinkage long sys_io_destroy(aio_context_t ctx) 1309 { 1310 struct kioctx *ioctx = lookup_ioctx(ctx); 1311 if (likely(NULL != ioctx)) { 1312 io_destroy(ioctx); 1313 return 0; 1314 } 1315 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1316 return -EINVAL; 1317 } 1318 1319 /* 1320 * aio_p{read,write} are the default ki_retry methods for 1321 * IO_CMD_P{READ,WRITE}. They maintains kiocb retry state around potentially 1322 * multiple calls to f_op->aio_read(). They loop around partial progress 1323 * instead of returning -EIOCBRETRY because they don't have the means to call 1324 * kick_iocb(). 1325 */ 1326 static ssize_t aio_pread(struct kiocb *iocb) 1327 { 1328 struct file *file = iocb->ki_filp; 1329 struct address_space *mapping = file->f_mapping; 1330 struct inode *inode = mapping->host; 1331 ssize_t ret = 0; 1332 1333 do { 1334 ret = file->f_op->aio_read(iocb, iocb->ki_buf, 1335 iocb->ki_left, iocb->ki_pos); 1336 /* 1337 * Can't just depend on iocb->ki_left to determine 1338 * whether we are done. This may have been a short read. 1339 */ 1340 if (ret > 0) { 1341 iocb->ki_buf += ret; 1342 iocb->ki_left -= ret; 1343 } 1344 1345 /* 1346 * For pipes and sockets we return once we have some data; for 1347 * regular files we retry till we complete the entire read or 1348 * find that we can't read any more data (e.g short reads). 1349 */ 1350 } while (ret > 0 && iocb->ki_left > 0 && 1351 !S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)); 1352 1353 /* This means we must have transferred all that we could */ 1354 /* No need to retry anymore */ 1355 if ((ret == 0) || (iocb->ki_left == 0)) 1356 ret = iocb->ki_nbytes - iocb->ki_left; 1357 1358 return ret; 1359 } 1360 1361 /* see aio_pread() */ 1362 static ssize_t aio_pwrite(struct kiocb *iocb) 1363 { 1364 struct file *file = iocb->ki_filp; 1365 ssize_t ret = 0; 1366 1367 do { 1368 ret = file->f_op->aio_write(iocb, iocb->ki_buf, 1369 iocb->ki_left, iocb->ki_pos); 1370 if (ret > 0) { 1371 iocb->ki_buf += ret; 1372 iocb->ki_left -= ret; 1373 } 1374 } while (ret > 0 && iocb->ki_left > 0); 1375 1376 if ((ret == 0) || (iocb->ki_left == 0)) 1377 ret = iocb->ki_nbytes - iocb->ki_left; 1378 1379 return ret; 1380 } 1381 1382 static ssize_t aio_fdsync(struct kiocb *iocb) 1383 { 1384 struct file *file = iocb->ki_filp; 1385 ssize_t ret = -EINVAL; 1386 1387 if (file->f_op->aio_fsync) 1388 ret = file->f_op->aio_fsync(iocb, 1); 1389 return ret; 1390 } 1391 1392 static ssize_t aio_fsync(struct kiocb *iocb) 1393 { 1394 struct file *file = iocb->ki_filp; 1395 ssize_t ret = -EINVAL; 1396 1397 if (file->f_op->aio_fsync) 1398 ret = file->f_op->aio_fsync(iocb, 0); 1399 return ret; 1400 } 1401 1402 /* 1403 * aio_setup_iocb: 1404 * Performs the initial checks and aio retry method 1405 * setup for the kiocb at the time of io submission. 1406 */ 1407 static ssize_t aio_setup_iocb(struct kiocb *kiocb) 1408 { 1409 struct file *file = kiocb->ki_filp; 1410 ssize_t ret = 0; 1411 1412 switch (kiocb->ki_opcode) { 1413 case IOCB_CMD_PREAD: 1414 ret = -EBADF; 1415 if (unlikely(!(file->f_mode & FMODE_READ))) 1416 break; 1417 ret = -EFAULT; 1418 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, 1419 kiocb->ki_left))) 1420 break; 1421 ret = -EINVAL; 1422 if (file->f_op->aio_read) 1423 kiocb->ki_retry = aio_pread; 1424 break; 1425 case IOCB_CMD_PWRITE: 1426 ret = -EBADF; 1427 if (unlikely(!(file->f_mode & FMODE_WRITE))) 1428 break; 1429 ret = -EFAULT; 1430 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, 1431 kiocb->ki_left))) 1432 break; 1433 ret = -EINVAL; 1434 if (file->f_op->aio_write) 1435 kiocb->ki_retry = aio_pwrite; 1436 break; 1437 case IOCB_CMD_FDSYNC: 1438 ret = -EINVAL; 1439 if (file->f_op->aio_fsync) 1440 kiocb->ki_retry = aio_fdsync; 1441 break; 1442 case IOCB_CMD_FSYNC: 1443 ret = -EINVAL; 1444 if (file->f_op->aio_fsync) 1445 kiocb->ki_retry = aio_fsync; 1446 break; 1447 default: 1448 dprintk("EINVAL: io_submit: no operation provided\n"); 1449 ret = -EINVAL; 1450 } 1451 1452 if (!kiocb->ki_retry) 1453 return ret; 1454 1455 return 0; 1456 } 1457 1458 /* 1459 * aio_wake_function: 1460 * wait queue callback function for aio notification, 1461 * Simply triggers a retry of the operation via kick_iocb. 1462 * 1463 * This callback is specified in the wait queue entry in 1464 * a kiocb (current->io_wait points to this wait queue 1465 * entry when an aio operation executes; it is used 1466 * instead of a synchronous wait when an i/o blocking 1467 * condition is encountered during aio). 1468 * 1469 * Note: 1470 * This routine is executed with the wait queue lock held. 1471 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests 1472 * the ioctx lock inside the wait queue lock. This is safe 1473 * because this callback isn't used for wait queues which 1474 * are nested inside ioctx lock (i.e. ctx->wait) 1475 */ 1476 static int aio_wake_function(wait_queue_t *wait, unsigned mode, 1477 int sync, void *key) 1478 { 1479 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); 1480 1481 list_del_init(&wait->task_list); 1482 kick_iocb(iocb); 1483 return 1; 1484 } 1485 1486 int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1487 struct iocb *iocb) 1488 { 1489 struct kiocb *req; 1490 struct file *file; 1491 ssize_t ret; 1492 1493 /* enforce forwards compatibility on users */ 1494 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || 1495 iocb->aio_reserved3)) { 1496 pr_debug("EINVAL: io_submit: reserve field set\n"); 1497 return -EINVAL; 1498 } 1499 1500 /* prevent overflows */ 1501 if (unlikely( 1502 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1503 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1504 ((ssize_t)iocb->aio_nbytes < 0) 1505 )) { 1506 pr_debug("EINVAL: io_submit: overflow check\n"); 1507 return -EINVAL; 1508 } 1509 1510 file = fget(iocb->aio_fildes); 1511 if (unlikely(!file)) 1512 return -EBADF; 1513 1514 req = aio_get_req(ctx); /* returns with 2 references to req */ 1515 if (unlikely(!req)) { 1516 fput(file); 1517 return -EAGAIN; 1518 } 1519 1520 req->ki_filp = file; 1521 ret = put_user(req->ki_key, &user_iocb->aio_key); 1522 if (unlikely(ret)) { 1523 dprintk("EFAULT: aio_key\n"); 1524 goto out_put_req; 1525 } 1526 1527 req->ki_obj.user = user_iocb; 1528 req->ki_user_data = iocb->aio_data; 1529 req->ki_pos = iocb->aio_offset; 1530 1531 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; 1532 req->ki_left = req->ki_nbytes = iocb->aio_nbytes; 1533 req->ki_opcode = iocb->aio_lio_opcode; 1534 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); 1535 INIT_LIST_HEAD(&req->ki_wait.task_list); 1536 req->ki_retried = 0; 1537 1538 ret = aio_setup_iocb(req); 1539 1540 if (ret) 1541 goto out_put_req; 1542 1543 spin_lock_irq(&ctx->ctx_lock); 1544 aio_run_iocb(req); 1545 unlock_kiocb(req); 1546 if (!list_empty(&ctx->run_list)) { 1547 /* drain the run list */ 1548 while (__aio_run_iocbs(ctx)) 1549 ; 1550 } 1551 spin_unlock_irq(&ctx->ctx_lock); 1552 aio_put_req(req); /* drop extra ref to req */ 1553 return 0; 1554 1555 out_put_req: 1556 aio_put_req(req); /* drop extra ref to req */ 1557 aio_put_req(req); /* drop i/o ref to req */ 1558 return ret; 1559 } 1560 1561 /* sys_io_submit: 1562 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1563 * the number of iocbs queued. May return -EINVAL if the aio_context 1564 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1565 * *iocbpp[0] is not properly initialized, if the operation specified 1566 * is invalid for the file descriptor in the iocb. May fail with 1567 * -EFAULT if any of the data structures point to invalid data. May 1568 * fail with -EBADF if the file descriptor specified in the first 1569 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1570 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1571 * fail with -ENOSYS if not implemented. 1572 */ 1573 asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, 1574 struct iocb __user * __user *iocbpp) 1575 { 1576 struct kioctx *ctx; 1577 long ret = 0; 1578 int i; 1579 1580 if (unlikely(nr < 0)) 1581 return -EINVAL; 1582 1583 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1584 return -EFAULT; 1585 1586 ctx = lookup_ioctx(ctx_id); 1587 if (unlikely(!ctx)) { 1588 pr_debug("EINVAL: io_submit: invalid context id\n"); 1589 return -EINVAL; 1590 } 1591 1592 /* 1593 * AKPM: should this return a partial result if some of the IOs were 1594 * successfully submitted? 1595 */ 1596 for (i=0; i<nr; i++) { 1597 struct iocb __user *user_iocb; 1598 struct iocb tmp; 1599 1600 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1601 ret = -EFAULT; 1602 break; 1603 } 1604 1605 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1606 ret = -EFAULT; 1607 break; 1608 } 1609 1610 ret = io_submit_one(ctx, user_iocb, &tmp); 1611 if (ret) 1612 break; 1613 } 1614 1615 put_ioctx(ctx); 1616 return i ? i : ret; 1617 } 1618 1619 /* lookup_kiocb 1620 * Finds a given iocb for cancellation. 1621 * MUST be called with ctx->ctx_lock held. 1622 */ 1623 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1624 u32 key) 1625 { 1626 struct list_head *pos; 1627 /* TODO: use a hash or array, this sucks. */ 1628 list_for_each(pos, &ctx->active_reqs) { 1629 struct kiocb *kiocb = list_kiocb(pos); 1630 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) 1631 return kiocb; 1632 } 1633 return NULL; 1634 } 1635 1636 /* sys_io_cancel: 1637 * Attempts to cancel an iocb previously passed to io_submit. If 1638 * the operation is successfully cancelled, the resulting event is 1639 * copied into the memory pointed to by result without being placed 1640 * into the completion queue and 0 is returned. May fail with 1641 * -EFAULT if any of the data structures pointed to are invalid. 1642 * May fail with -EINVAL if aio_context specified by ctx_id is 1643 * invalid. May fail with -EAGAIN if the iocb specified was not 1644 * cancelled. Will fail with -ENOSYS if not implemented. 1645 */ 1646 asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, 1647 struct io_event __user *result) 1648 { 1649 int (*cancel)(struct kiocb *iocb, struct io_event *res); 1650 struct kioctx *ctx; 1651 struct kiocb *kiocb; 1652 u32 key; 1653 int ret; 1654 1655 ret = get_user(key, &iocb->aio_key); 1656 if (unlikely(ret)) 1657 return -EFAULT; 1658 1659 ctx = lookup_ioctx(ctx_id); 1660 if (unlikely(!ctx)) 1661 return -EINVAL; 1662 1663 spin_lock_irq(&ctx->ctx_lock); 1664 ret = -EAGAIN; 1665 kiocb = lookup_kiocb(ctx, iocb, key); 1666 if (kiocb && kiocb->ki_cancel) { 1667 cancel = kiocb->ki_cancel; 1668 kiocb->ki_users ++; 1669 kiocbSetCancelled(kiocb); 1670 } else 1671 cancel = NULL; 1672 spin_unlock_irq(&ctx->ctx_lock); 1673 1674 if (NULL != cancel) { 1675 struct io_event tmp; 1676 pr_debug("calling cancel\n"); 1677 lock_kiocb(kiocb); 1678 memset(&tmp, 0, sizeof(tmp)); 1679 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; 1680 tmp.data = kiocb->ki_user_data; 1681 ret = cancel(kiocb, &tmp); 1682 if (!ret) { 1683 /* Cancellation succeeded -- copy the result 1684 * into the user's buffer. 1685 */ 1686 if (copy_to_user(result, &tmp, sizeof(tmp))) 1687 ret = -EFAULT; 1688 } 1689 unlock_kiocb(kiocb); 1690 } else 1691 ret = -EINVAL; 1692 1693 put_ioctx(ctx); 1694 1695 return ret; 1696 } 1697 1698 /* io_getevents: 1699 * Attempts to read at least min_nr events and up to nr events from 1700 * the completion queue for the aio_context specified by ctx_id. May 1701 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, 1702 * if nr is out of range, if when is out of range. May fail with 1703 * -EFAULT if any of the memory specified to is invalid. May return 1704 * 0 or < min_nr if no events are available and the timeout specified 1705 * by when has elapsed, where when == NULL specifies an infinite 1706 * timeout. Note that the timeout pointed to by when is relative and 1707 * will be updated if not NULL and the operation blocks. Will fail 1708 * with -ENOSYS if not implemented. 1709 */ 1710 asmlinkage long sys_io_getevents(aio_context_t ctx_id, 1711 long min_nr, 1712 long nr, 1713 struct io_event __user *events, 1714 struct timespec __user *timeout) 1715 { 1716 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1717 long ret = -EINVAL; 1718 1719 if (likely(ioctx)) { 1720 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) 1721 ret = read_events(ioctx, min_nr, nr, events, timeout); 1722 put_ioctx(ioctx); 1723 } 1724 1725 return ret; 1726 } 1727 1728 __initcall(aio_setup); 1729 1730 EXPORT_SYMBOL(aio_complete); 1731 EXPORT_SYMBOL(aio_put_req); 1732 EXPORT_SYMBOL(wait_on_sync_kiocb); 1733