1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/kernel.h> 3 #include <linux/errno.h> 4 #include <linux/fs.h> 5 #include <linux/file.h> 6 #include <linux/blk-mq.h> 7 #include <linux/mm.h> 8 #include <linux/slab.h> 9 #include <linux/fsnotify.h> 10 #include <linux/poll.h> 11 #include <linux/nospec.h> 12 #include <linux/compat.h> 13 #include <linux/io_uring.h> 14 15 #include <uapi/linux/io_uring.h> 16 17 #include "io_uring.h" 18 #include "opdef.h" 19 #include "kbuf.h" 20 #include "rsrc.h" 21 #include "rw.h" 22 23 struct io_rw { 24 /* NOTE: kiocb has the file as the first member, so don't do it here */ 25 struct kiocb kiocb; 26 u64 addr; 27 u32 len; 28 rwf_t flags; 29 }; 30 31 static inline bool io_file_supports_nowait(struct io_kiocb *req) 32 { 33 return req->flags & REQ_F_SUPPORT_NOWAIT; 34 } 35 36 #ifdef CONFIG_COMPAT 37 static int io_iov_compat_buffer_select_prep(struct io_rw *rw) 38 { 39 struct compat_iovec __user *uiov; 40 compat_ssize_t clen; 41 42 uiov = u64_to_user_ptr(rw->addr); 43 if (!access_ok(uiov, sizeof(*uiov))) 44 return -EFAULT; 45 if (__get_user(clen, &uiov->iov_len)) 46 return -EFAULT; 47 if (clen < 0) 48 return -EINVAL; 49 50 rw->len = clen; 51 return 0; 52 } 53 #endif 54 55 static int io_iov_buffer_select_prep(struct io_kiocb *req) 56 { 57 struct iovec __user *uiov; 58 struct iovec iov; 59 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 60 61 if (rw->len != 1) 62 return -EINVAL; 63 64 #ifdef CONFIG_COMPAT 65 if (req->ctx->compat) 66 return io_iov_compat_buffer_select_prep(rw); 67 #endif 68 69 uiov = u64_to_user_ptr(rw->addr); 70 if (copy_from_user(&iov, uiov, sizeof(*uiov))) 71 return -EFAULT; 72 rw->len = iov.iov_len; 73 return 0; 74 } 75 76 int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe) 77 { 78 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 79 unsigned ioprio; 80 int ret; 81 82 rw->kiocb.ki_pos = READ_ONCE(sqe->off); 83 /* used for fixed read/write too - just read unconditionally */ 84 req->buf_index = READ_ONCE(sqe->buf_index); 85 86 if (req->opcode == IORING_OP_READ_FIXED || 87 req->opcode == IORING_OP_WRITE_FIXED) { 88 struct io_ring_ctx *ctx = req->ctx; 89 u16 index; 90 91 if (unlikely(req->buf_index >= ctx->nr_user_bufs)) 92 return -EFAULT; 93 index = array_index_nospec(req->buf_index, ctx->nr_user_bufs); 94 req->imu = ctx->user_bufs[index]; 95 io_req_set_rsrc_node(req, ctx, 0); 96 } 97 98 ioprio = READ_ONCE(sqe->ioprio); 99 if (ioprio) { 100 ret = ioprio_check_cap(ioprio); 101 if (ret) 102 return ret; 103 104 rw->kiocb.ki_ioprio = ioprio; 105 } else { 106 rw->kiocb.ki_ioprio = get_current_ioprio(); 107 } 108 rw->kiocb.dio_complete = NULL; 109 110 rw->addr = READ_ONCE(sqe->addr); 111 rw->len = READ_ONCE(sqe->len); 112 rw->flags = READ_ONCE(sqe->rw_flags); 113 114 /* Have to do this validation here, as this is in io_read() rw->len might 115 * have chanaged due to buffer selection 116 */ 117 if (req->opcode == IORING_OP_READV && req->flags & REQ_F_BUFFER_SELECT) { 118 ret = io_iov_buffer_select_prep(req); 119 if (ret) 120 return ret; 121 } 122 123 return 0; 124 } 125 126 void io_readv_writev_cleanup(struct io_kiocb *req) 127 { 128 struct io_async_rw *io = req->async_data; 129 130 kfree(io->free_iovec); 131 } 132 133 static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) 134 { 135 switch (ret) { 136 case -EIOCBQUEUED: 137 break; 138 case -ERESTARTSYS: 139 case -ERESTARTNOINTR: 140 case -ERESTARTNOHAND: 141 case -ERESTART_RESTARTBLOCK: 142 /* 143 * We can't just restart the syscall, since previously 144 * submitted sqes may already be in progress. Just fail this 145 * IO with EINTR. 146 */ 147 ret = -EINTR; 148 fallthrough; 149 default: 150 kiocb->ki_complete(kiocb, ret); 151 } 152 } 153 154 static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req) 155 { 156 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 157 158 if (rw->kiocb.ki_pos != -1) 159 return &rw->kiocb.ki_pos; 160 161 if (!(req->file->f_mode & FMODE_STREAM)) { 162 req->flags |= REQ_F_CUR_POS; 163 rw->kiocb.ki_pos = req->file->f_pos; 164 return &rw->kiocb.ki_pos; 165 } 166 167 rw->kiocb.ki_pos = 0; 168 return NULL; 169 } 170 171 static void io_req_task_queue_reissue(struct io_kiocb *req) 172 { 173 req->io_task_work.func = io_queue_iowq; 174 io_req_task_work_add(req); 175 } 176 177 #ifdef CONFIG_BLOCK 178 static bool io_resubmit_prep(struct io_kiocb *req) 179 { 180 struct io_async_rw *io = req->async_data; 181 182 if (!req_has_async_data(req)) 183 return !io_req_prep_async(req); 184 iov_iter_restore(&io->s.iter, &io->s.iter_state); 185 return true; 186 } 187 188 static bool io_rw_should_reissue(struct io_kiocb *req) 189 { 190 umode_t mode = file_inode(req->file)->i_mode; 191 struct io_ring_ctx *ctx = req->ctx; 192 193 if (!S_ISBLK(mode) && !S_ISREG(mode)) 194 return false; 195 if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() && 196 !(ctx->flags & IORING_SETUP_IOPOLL))) 197 return false; 198 /* 199 * If ref is dying, we might be running poll reap from the exit work. 200 * Don't attempt to reissue from that path, just let it fail with 201 * -EAGAIN. 202 */ 203 if (percpu_ref_is_dying(&ctx->refs)) 204 return false; 205 /* 206 * Play it safe and assume not safe to re-import and reissue if we're 207 * not in the original thread group (or in task context). 208 */ 209 if (!same_thread_group(req->task, current) || !in_task()) 210 return false; 211 return true; 212 } 213 #else 214 static bool io_resubmit_prep(struct io_kiocb *req) 215 { 216 return false; 217 } 218 static bool io_rw_should_reissue(struct io_kiocb *req) 219 { 220 return false; 221 } 222 #endif 223 224 static void kiocb_end_write(struct io_kiocb *req) 225 { 226 /* 227 * Tell lockdep we inherited freeze protection from submission 228 * thread. 229 */ 230 if (req->flags & REQ_F_ISREG) { 231 struct super_block *sb = file_inode(req->file)->i_sb; 232 233 __sb_writers_acquired(sb, SB_FREEZE_WRITE); 234 sb_end_write(sb); 235 } 236 } 237 238 /* 239 * Trigger the notifications after having done some IO, and finish the write 240 * accounting, if any. 241 */ 242 static void io_req_io_end(struct io_kiocb *req) 243 { 244 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 245 246 if (rw->kiocb.ki_flags & IOCB_WRITE) { 247 kiocb_end_write(req); 248 fsnotify_modify(req->file); 249 } else { 250 fsnotify_access(req->file); 251 } 252 } 253 254 static bool __io_complete_rw_common(struct io_kiocb *req, long res) 255 { 256 if (unlikely(res != req->cqe.res)) { 257 if ((res == -EAGAIN || res == -EOPNOTSUPP) && 258 io_rw_should_reissue(req)) { 259 /* 260 * Reissue will start accounting again, finish the 261 * current cycle. 262 */ 263 io_req_io_end(req); 264 req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; 265 return true; 266 } 267 req_set_fail(req); 268 req->cqe.res = res; 269 } 270 return false; 271 } 272 273 static inline int io_fixup_rw_res(struct io_kiocb *req, long res) 274 { 275 struct io_async_rw *io = req->async_data; 276 277 /* add previously done IO, if any */ 278 if (req_has_async_data(req) && io->bytes_done > 0) { 279 if (res < 0) 280 res = io->bytes_done; 281 else 282 res += io->bytes_done; 283 } 284 return res; 285 } 286 287 void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts) 288 { 289 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 290 struct kiocb *kiocb = &rw->kiocb; 291 292 if ((kiocb->ki_flags & IOCB_DIO_CALLER_COMP) && kiocb->dio_complete) { 293 long res = kiocb->dio_complete(rw->kiocb.private); 294 295 io_req_set_res(req, io_fixup_rw_res(req, res), 0); 296 } 297 298 io_req_io_end(req); 299 300 if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) { 301 unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED; 302 303 req->cqe.flags |= io_put_kbuf(req, issue_flags); 304 } 305 io_req_task_complete(req, ts); 306 } 307 308 static void io_complete_rw(struct kiocb *kiocb, long res) 309 { 310 struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); 311 struct io_kiocb *req = cmd_to_io_kiocb(rw); 312 313 if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) { 314 if (__io_complete_rw_common(req, res)) 315 return; 316 io_req_set_res(req, io_fixup_rw_res(req, res), 0); 317 } 318 req->io_task_work.func = io_req_rw_complete; 319 __io_req_task_work_add(req, IOU_F_TWQ_LAZY_WAKE); 320 } 321 322 static void io_complete_rw_iopoll(struct kiocb *kiocb, long res) 323 { 324 struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); 325 struct io_kiocb *req = cmd_to_io_kiocb(rw); 326 327 if (kiocb->ki_flags & IOCB_WRITE) 328 kiocb_end_write(req); 329 if (unlikely(res != req->cqe.res)) { 330 if (res == -EAGAIN && io_rw_should_reissue(req)) { 331 req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; 332 return; 333 } 334 req->cqe.res = res; 335 } 336 337 /* order with io_iopoll_complete() checking ->iopoll_completed */ 338 smp_store_release(&req->iopoll_completed, 1); 339 } 340 341 static int kiocb_done(struct io_kiocb *req, ssize_t ret, 342 unsigned int issue_flags) 343 { 344 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 345 unsigned final_ret = io_fixup_rw_res(req, ret); 346 347 if (req->flags & REQ_F_CUR_POS) 348 req->file->f_pos = rw->kiocb.ki_pos; 349 if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) { 350 if (!__io_complete_rw_common(req, ret)) { 351 /* 352 * Safe to call io_end from here as we're inline 353 * from the submission path. 354 */ 355 io_req_io_end(req); 356 io_req_set_res(req, final_ret, 357 io_put_kbuf(req, issue_flags)); 358 return IOU_OK; 359 } 360 } else { 361 io_rw_done(&rw->kiocb, ret); 362 } 363 364 if (req->flags & REQ_F_REISSUE) { 365 req->flags &= ~REQ_F_REISSUE; 366 if (io_resubmit_prep(req)) 367 io_req_task_queue_reissue(req); 368 else 369 io_req_task_queue_fail(req, final_ret); 370 } 371 return IOU_ISSUE_SKIP_COMPLETE; 372 } 373 374 static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req, 375 struct io_rw_state *s, 376 unsigned int issue_flags) 377 { 378 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 379 struct iov_iter *iter = &s->iter; 380 u8 opcode = req->opcode; 381 struct iovec *iovec; 382 void __user *buf; 383 size_t sqe_len; 384 ssize_t ret; 385 386 if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) { 387 ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len); 388 if (ret) 389 return ERR_PTR(ret); 390 return NULL; 391 } 392 393 buf = u64_to_user_ptr(rw->addr); 394 sqe_len = rw->len; 395 396 if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE || 397 (req->flags & REQ_F_BUFFER_SELECT)) { 398 if (io_do_buffer_select(req)) { 399 buf = io_buffer_select(req, &sqe_len, issue_flags); 400 if (!buf) 401 return ERR_PTR(-ENOBUFS); 402 rw->addr = (unsigned long) buf; 403 rw->len = sqe_len; 404 } 405 406 ret = import_ubuf(ddir, buf, sqe_len, iter); 407 if (ret) 408 return ERR_PTR(ret); 409 return NULL; 410 } 411 412 iovec = s->fast_iov; 413 ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter, 414 req->ctx->compat); 415 if (unlikely(ret < 0)) 416 return ERR_PTR(ret); 417 return iovec; 418 } 419 420 static inline int io_import_iovec(int rw, struct io_kiocb *req, 421 struct iovec **iovec, struct io_rw_state *s, 422 unsigned int issue_flags) 423 { 424 *iovec = __io_import_iovec(rw, req, s, issue_flags); 425 if (IS_ERR(*iovec)) 426 return PTR_ERR(*iovec); 427 428 iov_iter_save_state(&s->iter, &s->iter_state); 429 return 0; 430 } 431 432 static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb) 433 { 434 return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos; 435 } 436 437 /* 438 * For files that don't have ->read_iter() and ->write_iter(), handle them 439 * by looping over ->read() or ->write() manually. 440 */ 441 static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter) 442 { 443 struct kiocb *kiocb = &rw->kiocb; 444 struct file *file = kiocb->ki_filp; 445 ssize_t ret = 0; 446 loff_t *ppos; 447 448 /* 449 * Don't support polled IO through this interface, and we can't 450 * support non-blocking either. For the latter, this just causes 451 * the kiocb to be handled from an async context. 452 */ 453 if (kiocb->ki_flags & IOCB_HIPRI) 454 return -EOPNOTSUPP; 455 if ((kiocb->ki_flags & IOCB_NOWAIT) && 456 !(kiocb->ki_filp->f_flags & O_NONBLOCK)) 457 return -EAGAIN; 458 459 ppos = io_kiocb_ppos(kiocb); 460 461 while (iov_iter_count(iter)) { 462 void __user *addr; 463 size_t len; 464 ssize_t nr; 465 466 if (iter_is_ubuf(iter)) { 467 addr = iter->ubuf + iter->iov_offset; 468 len = iov_iter_count(iter); 469 } else if (!iov_iter_is_bvec(iter)) { 470 addr = iter_iov_addr(iter); 471 len = iter_iov_len(iter); 472 } else { 473 addr = u64_to_user_ptr(rw->addr); 474 len = rw->len; 475 } 476 477 if (ddir == READ) 478 nr = file->f_op->read(file, addr, len, ppos); 479 else 480 nr = file->f_op->write(file, addr, len, ppos); 481 482 if (nr < 0) { 483 if (!ret) 484 ret = nr; 485 break; 486 } 487 ret += nr; 488 if (!iov_iter_is_bvec(iter)) { 489 iov_iter_advance(iter, nr); 490 } else { 491 rw->addr += nr; 492 rw->len -= nr; 493 if (!rw->len) 494 break; 495 } 496 if (nr != len) 497 break; 498 } 499 500 return ret; 501 } 502 503 static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec, 504 const struct iovec *fast_iov, struct iov_iter *iter) 505 { 506 struct io_async_rw *io = req->async_data; 507 508 memcpy(&io->s.iter, iter, sizeof(*iter)); 509 io->free_iovec = iovec; 510 io->bytes_done = 0; 511 /* can only be fixed buffers, no need to do anything */ 512 if (iov_iter_is_bvec(iter) || iter_is_ubuf(iter)) 513 return; 514 if (!iovec) { 515 unsigned iov_off = 0; 516 517 io->s.iter.__iov = io->s.fast_iov; 518 if (iter->__iov != fast_iov) { 519 iov_off = iter_iov(iter) - fast_iov; 520 io->s.iter.__iov += iov_off; 521 } 522 if (io->s.fast_iov != fast_iov) 523 memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off, 524 sizeof(struct iovec) * iter->nr_segs); 525 } else { 526 req->flags |= REQ_F_NEED_CLEANUP; 527 } 528 } 529 530 static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec, 531 struct io_rw_state *s, bool force) 532 { 533 if (!force && !io_cold_defs[req->opcode].prep_async) 534 return 0; 535 if (!req_has_async_data(req)) { 536 struct io_async_rw *iorw; 537 538 if (io_alloc_async_data(req)) { 539 kfree(iovec); 540 return -ENOMEM; 541 } 542 543 io_req_map_rw(req, iovec, s->fast_iov, &s->iter); 544 iorw = req->async_data; 545 /* we've copied and mapped the iter, ensure state is saved */ 546 iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state); 547 } 548 return 0; 549 } 550 551 static inline int io_rw_prep_async(struct io_kiocb *req, int rw) 552 { 553 struct io_async_rw *iorw = req->async_data; 554 struct iovec *iov; 555 int ret; 556 557 /* submission path, ->uring_lock should already be taken */ 558 ret = io_import_iovec(rw, req, &iov, &iorw->s, 0); 559 if (unlikely(ret < 0)) 560 return ret; 561 562 iorw->bytes_done = 0; 563 iorw->free_iovec = iov; 564 if (iov) 565 req->flags |= REQ_F_NEED_CLEANUP; 566 return 0; 567 } 568 569 int io_readv_prep_async(struct io_kiocb *req) 570 { 571 return io_rw_prep_async(req, ITER_DEST); 572 } 573 574 int io_writev_prep_async(struct io_kiocb *req) 575 { 576 return io_rw_prep_async(req, ITER_SOURCE); 577 } 578 579 /* 580 * This is our waitqueue callback handler, registered through __folio_lock_async() 581 * when we initially tried to do the IO with the iocb armed our waitqueue. 582 * This gets called when the page is unlocked, and we generally expect that to 583 * happen when the page IO is completed and the page is now uptodate. This will 584 * queue a task_work based retry of the operation, attempting to copy the data 585 * again. If the latter fails because the page was NOT uptodate, then we will 586 * do a thread based blocking retry of the operation. That's the unexpected 587 * slow path. 588 */ 589 static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode, 590 int sync, void *arg) 591 { 592 struct wait_page_queue *wpq; 593 struct io_kiocb *req = wait->private; 594 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 595 struct wait_page_key *key = arg; 596 597 wpq = container_of(wait, struct wait_page_queue, wait); 598 599 if (!wake_page_match(wpq, key)) 600 return 0; 601 602 rw->kiocb.ki_flags &= ~IOCB_WAITQ; 603 list_del_init(&wait->entry); 604 io_req_task_queue(req); 605 return 1; 606 } 607 608 /* 609 * This controls whether a given IO request should be armed for async page 610 * based retry. If we return false here, the request is handed to the async 611 * worker threads for retry. If we're doing buffered reads on a regular file, 612 * we prepare a private wait_page_queue entry and retry the operation. This 613 * will either succeed because the page is now uptodate and unlocked, or it 614 * will register a callback when the page is unlocked at IO completion. Through 615 * that callback, io_uring uses task_work to setup a retry of the operation. 616 * That retry will attempt the buffered read again. The retry will generally 617 * succeed, or in rare cases where it fails, we then fall back to using the 618 * async worker threads for a blocking retry. 619 */ 620 static bool io_rw_should_retry(struct io_kiocb *req) 621 { 622 struct io_async_rw *io = req->async_data; 623 struct wait_page_queue *wait = &io->wpq; 624 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 625 struct kiocb *kiocb = &rw->kiocb; 626 627 /* never retry for NOWAIT, we just complete with -EAGAIN */ 628 if (req->flags & REQ_F_NOWAIT) 629 return false; 630 631 /* Only for buffered IO */ 632 if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI)) 633 return false; 634 635 /* 636 * just use poll if we can, and don't attempt if the fs doesn't 637 * support callback based unlocks 638 */ 639 if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC)) 640 return false; 641 642 wait->wait.func = io_async_buf_func; 643 wait->wait.private = req; 644 wait->wait.flags = 0; 645 INIT_LIST_HEAD(&wait->wait.entry); 646 kiocb->ki_flags |= IOCB_WAITQ; 647 kiocb->ki_flags &= ~IOCB_NOWAIT; 648 kiocb->ki_waitq = wait; 649 return true; 650 } 651 652 static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter) 653 { 654 struct file *file = rw->kiocb.ki_filp; 655 656 if (likely(file->f_op->read_iter)) 657 return call_read_iter(file, &rw->kiocb, iter); 658 else if (file->f_op->read) 659 return loop_rw_iter(READ, rw, iter); 660 else 661 return -EINVAL; 662 } 663 664 static bool need_complete_io(struct io_kiocb *req) 665 { 666 return req->flags & REQ_F_ISREG || 667 S_ISBLK(file_inode(req->file)->i_mode); 668 } 669 670 static int io_rw_init_file(struct io_kiocb *req, fmode_t mode) 671 { 672 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 673 struct kiocb *kiocb = &rw->kiocb; 674 struct io_ring_ctx *ctx = req->ctx; 675 struct file *file = req->file; 676 int ret; 677 678 if (unlikely(!file || !(file->f_mode & mode))) 679 return -EBADF; 680 681 if (!(req->flags & REQ_F_FIXED_FILE)) 682 req->flags |= io_file_get_flags(file); 683 684 kiocb->ki_flags = file->f_iocb_flags; 685 ret = kiocb_set_rw_flags(kiocb, rw->flags); 686 if (unlikely(ret)) 687 return ret; 688 kiocb->ki_flags |= IOCB_ALLOC_CACHE; 689 690 /* 691 * If the file is marked O_NONBLOCK, still allow retry for it if it 692 * supports async. Otherwise it's impossible to use O_NONBLOCK files 693 * reliably. If not, or it IOCB_NOWAIT is set, don't retry. 694 */ 695 if ((kiocb->ki_flags & IOCB_NOWAIT) || 696 ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req))) 697 req->flags |= REQ_F_NOWAIT; 698 699 if (ctx->flags & IORING_SETUP_IOPOLL) { 700 if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll) 701 return -EOPNOTSUPP; 702 703 kiocb->private = NULL; 704 kiocb->ki_flags |= IOCB_HIPRI; 705 kiocb->ki_complete = io_complete_rw_iopoll; 706 req->iopoll_completed = 0; 707 } else { 708 if (kiocb->ki_flags & IOCB_HIPRI) 709 return -EINVAL; 710 kiocb->ki_complete = io_complete_rw; 711 } 712 713 return 0; 714 } 715 716 int io_read(struct io_kiocb *req, unsigned int issue_flags) 717 { 718 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 719 struct io_rw_state __s, *s = &__s; 720 struct iovec *iovec; 721 struct kiocb *kiocb = &rw->kiocb; 722 bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; 723 struct io_async_rw *io; 724 ssize_t ret, ret2; 725 loff_t *ppos; 726 727 if (!req_has_async_data(req)) { 728 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags); 729 if (unlikely(ret < 0)) 730 return ret; 731 } else { 732 io = req->async_data; 733 s = &io->s; 734 735 /* 736 * Safe and required to re-import if we're using provided 737 * buffers, as we dropped the selected one before retry. 738 */ 739 if (io_do_buffer_select(req)) { 740 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags); 741 if (unlikely(ret < 0)) 742 return ret; 743 } 744 745 /* 746 * We come here from an earlier attempt, restore our state to 747 * match in case it doesn't. It's cheap enough that we don't 748 * need to make this conditional. 749 */ 750 iov_iter_restore(&s->iter, &s->iter_state); 751 iovec = NULL; 752 } 753 ret = io_rw_init_file(req, FMODE_READ); 754 if (unlikely(ret)) { 755 kfree(iovec); 756 return ret; 757 } 758 req->cqe.res = iov_iter_count(&s->iter); 759 760 if (force_nonblock) { 761 /* If the file doesn't support async, just async punt */ 762 if (unlikely(!io_file_supports_nowait(req))) { 763 ret = io_setup_async_rw(req, iovec, s, true); 764 return ret ?: -EAGAIN; 765 } 766 kiocb->ki_flags |= IOCB_NOWAIT; 767 } else { 768 /* Ensure we clear previously set non-block flag */ 769 kiocb->ki_flags &= ~IOCB_NOWAIT; 770 } 771 772 ppos = io_kiocb_update_pos(req); 773 774 ret = rw_verify_area(READ, req->file, ppos, req->cqe.res); 775 if (unlikely(ret)) { 776 kfree(iovec); 777 return ret; 778 } 779 780 ret = io_iter_do_read(rw, &s->iter); 781 782 if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) { 783 req->flags &= ~REQ_F_REISSUE; 784 /* if we can poll, just do that */ 785 if (req->opcode == IORING_OP_READ && file_can_poll(req->file)) 786 return -EAGAIN; 787 /* IOPOLL retry should happen for io-wq threads */ 788 if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL)) 789 goto done; 790 /* no retry on NONBLOCK nor RWF_NOWAIT */ 791 if (req->flags & REQ_F_NOWAIT) 792 goto done; 793 ret = 0; 794 } else if (ret == -EIOCBQUEUED) { 795 if (iovec) 796 kfree(iovec); 797 return IOU_ISSUE_SKIP_COMPLETE; 798 } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock || 799 (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) { 800 /* read all, failed, already did sync or don't want to retry */ 801 goto done; 802 } 803 804 /* 805 * Don't depend on the iter state matching what was consumed, or being 806 * untouched in case of error. Restore it and we'll advance it 807 * manually if we need to. 808 */ 809 iov_iter_restore(&s->iter, &s->iter_state); 810 811 ret2 = io_setup_async_rw(req, iovec, s, true); 812 iovec = NULL; 813 if (ret2) { 814 ret = ret > 0 ? ret : ret2; 815 goto done; 816 } 817 818 io = req->async_data; 819 s = &io->s; 820 /* 821 * Now use our persistent iterator and state, if we aren't already. 822 * We've restored and mapped the iter to match. 823 */ 824 825 do { 826 /* 827 * We end up here because of a partial read, either from 828 * above or inside this loop. Advance the iter by the bytes 829 * that were consumed. 830 */ 831 iov_iter_advance(&s->iter, ret); 832 if (!iov_iter_count(&s->iter)) 833 break; 834 io->bytes_done += ret; 835 iov_iter_save_state(&s->iter, &s->iter_state); 836 837 /* if we can retry, do so with the callbacks armed */ 838 if (!io_rw_should_retry(req)) { 839 kiocb->ki_flags &= ~IOCB_WAITQ; 840 return -EAGAIN; 841 } 842 843 req->cqe.res = iov_iter_count(&s->iter); 844 /* 845 * Now retry read with the IOCB_WAITQ parts set in the iocb. If 846 * we get -EIOCBQUEUED, then we'll get a notification when the 847 * desired page gets unlocked. We can also get a partial read 848 * here, and if we do, then just retry at the new offset. 849 */ 850 ret = io_iter_do_read(rw, &s->iter); 851 if (ret == -EIOCBQUEUED) 852 return IOU_ISSUE_SKIP_COMPLETE; 853 /* we got some bytes, but not all. retry. */ 854 kiocb->ki_flags &= ~IOCB_WAITQ; 855 iov_iter_restore(&s->iter, &s->iter_state); 856 } while (ret > 0); 857 done: 858 /* it's faster to check here then delegate to kfree */ 859 if (iovec) 860 kfree(iovec); 861 return kiocb_done(req, ret, issue_flags); 862 } 863 864 int io_write(struct io_kiocb *req, unsigned int issue_flags) 865 { 866 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 867 struct io_rw_state __s, *s = &__s; 868 struct iovec *iovec; 869 struct kiocb *kiocb = &rw->kiocb; 870 bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; 871 ssize_t ret, ret2; 872 loff_t *ppos; 873 874 if (!req_has_async_data(req)) { 875 ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags); 876 if (unlikely(ret < 0)) 877 return ret; 878 } else { 879 struct io_async_rw *io = req->async_data; 880 881 s = &io->s; 882 iov_iter_restore(&s->iter, &s->iter_state); 883 iovec = NULL; 884 } 885 ret = io_rw_init_file(req, FMODE_WRITE); 886 if (unlikely(ret)) { 887 kfree(iovec); 888 return ret; 889 } 890 req->cqe.res = iov_iter_count(&s->iter); 891 892 if (force_nonblock) { 893 /* If the file doesn't support async, just async punt */ 894 if (unlikely(!io_file_supports_nowait(req))) 895 goto copy_iov; 896 897 /* File path supports NOWAIT for non-direct_IO only for block devices. */ 898 if (!(kiocb->ki_flags & IOCB_DIRECT) && 899 !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) && 900 (req->flags & REQ_F_ISREG)) 901 goto copy_iov; 902 903 kiocb->ki_flags |= IOCB_NOWAIT; 904 } else { 905 /* Ensure we clear previously set non-block flag */ 906 kiocb->ki_flags &= ~IOCB_NOWAIT; 907 } 908 909 ppos = io_kiocb_update_pos(req); 910 911 ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res); 912 if (unlikely(ret)) { 913 kfree(iovec); 914 return ret; 915 } 916 917 /* 918 * Open-code file_start_write here to grab freeze protection, 919 * which will be released by another thread in 920 * io_complete_rw(). Fool lockdep by telling it the lock got 921 * released so that it doesn't complain about the held lock when 922 * we return to userspace. 923 */ 924 if (req->flags & REQ_F_ISREG) { 925 sb_start_write(file_inode(req->file)->i_sb); 926 __sb_writers_release(file_inode(req->file)->i_sb, 927 SB_FREEZE_WRITE); 928 } 929 kiocb->ki_flags |= IOCB_WRITE; 930 931 /* 932 * For non-polled IO, set IOCB_DIO_CALLER_COMP, stating that our handler 933 * groks deferring the completion to task context. This isn't 934 * necessary and useful for polled IO as that can always complete 935 * directly. 936 */ 937 if (!(kiocb->ki_flags & IOCB_HIPRI)) 938 kiocb->ki_flags |= IOCB_DIO_CALLER_COMP; 939 940 if (likely(req->file->f_op->write_iter)) 941 ret2 = call_write_iter(req->file, kiocb, &s->iter); 942 else if (req->file->f_op->write) 943 ret2 = loop_rw_iter(WRITE, rw, &s->iter); 944 else 945 ret2 = -EINVAL; 946 947 if (req->flags & REQ_F_REISSUE) { 948 req->flags &= ~REQ_F_REISSUE; 949 ret2 = -EAGAIN; 950 } 951 952 /* 953 * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just 954 * retry them without IOCB_NOWAIT. 955 */ 956 if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT)) 957 ret2 = -EAGAIN; 958 /* no retry on NONBLOCK nor RWF_NOWAIT */ 959 if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT)) 960 goto done; 961 if (!force_nonblock || ret2 != -EAGAIN) { 962 /* IOPOLL retry should happen for io-wq threads */ 963 if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL)) 964 goto copy_iov; 965 966 if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) { 967 struct io_async_rw *io; 968 969 trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2, 970 req->cqe.res, ret2); 971 972 /* This is a partial write. The file pos has already been 973 * updated, setup the async struct to complete the request 974 * in the worker. Also update bytes_done to account for 975 * the bytes already written. 976 */ 977 iov_iter_save_state(&s->iter, &s->iter_state); 978 ret = io_setup_async_rw(req, iovec, s, true); 979 980 io = req->async_data; 981 if (io) 982 io->bytes_done += ret2; 983 984 if (kiocb->ki_flags & IOCB_WRITE) 985 kiocb_end_write(req); 986 return ret ? ret : -EAGAIN; 987 } 988 done: 989 ret = kiocb_done(req, ret2, issue_flags); 990 } else { 991 copy_iov: 992 iov_iter_restore(&s->iter, &s->iter_state); 993 ret = io_setup_async_rw(req, iovec, s, false); 994 if (!ret) { 995 if (kiocb->ki_flags & IOCB_WRITE) 996 kiocb_end_write(req); 997 return -EAGAIN; 998 } 999 return ret; 1000 } 1001 /* it's reportedly faster than delegating the null check to kfree() */ 1002 if (iovec) 1003 kfree(iovec); 1004 return ret; 1005 } 1006 1007 static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx) 1008 { 1009 io_commit_cqring_flush(ctx); 1010 if (ctx->flags & IORING_SETUP_SQPOLL) 1011 io_cqring_wake(ctx); 1012 } 1013 1014 void io_rw_fail(struct io_kiocb *req) 1015 { 1016 int res; 1017 1018 res = io_fixup_rw_res(req, req->cqe.res); 1019 io_req_set_res(req, res, req->cqe.flags); 1020 } 1021 1022 int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin) 1023 { 1024 struct io_wq_work_node *pos, *start, *prev; 1025 unsigned int poll_flags = 0; 1026 DEFINE_IO_COMP_BATCH(iob); 1027 int nr_events = 0; 1028 1029 /* 1030 * Only spin for completions if we don't have multiple devices hanging 1031 * off our complete list. 1032 */ 1033 if (ctx->poll_multi_queue || force_nonspin) 1034 poll_flags |= BLK_POLL_ONESHOT; 1035 1036 wq_list_for_each(pos, start, &ctx->iopoll_list) { 1037 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list); 1038 struct file *file = req->file; 1039 int ret; 1040 1041 /* 1042 * Move completed and retryable entries to our local lists. 1043 * If we find a request that requires polling, break out 1044 * and complete those lists first, if we have entries there. 1045 */ 1046 if (READ_ONCE(req->iopoll_completed)) 1047 break; 1048 1049 if (req->opcode == IORING_OP_URING_CMD) { 1050 struct io_uring_cmd *ioucmd; 1051 1052 ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); 1053 ret = file->f_op->uring_cmd_iopoll(ioucmd, &iob, 1054 poll_flags); 1055 } else { 1056 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); 1057 1058 ret = file->f_op->iopoll(&rw->kiocb, &iob, poll_flags); 1059 } 1060 if (unlikely(ret < 0)) 1061 return ret; 1062 else if (ret) 1063 poll_flags |= BLK_POLL_ONESHOT; 1064 1065 /* iopoll may have completed current req */ 1066 if (!rq_list_empty(iob.req_list) || 1067 READ_ONCE(req->iopoll_completed)) 1068 break; 1069 } 1070 1071 if (!rq_list_empty(iob.req_list)) 1072 iob.complete(&iob); 1073 else if (!pos) 1074 return 0; 1075 1076 prev = start; 1077 wq_list_for_each_resume(pos, prev) { 1078 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list); 1079 1080 /* order with io_complete_rw_iopoll(), e.g. ->result updates */ 1081 if (!smp_load_acquire(&req->iopoll_completed)) 1082 break; 1083 nr_events++; 1084 if (unlikely(req->flags & REQ_F_CQE_SKIP)) 1085 continue; 1086 1087 req->cqe.flags = io_put_kbuf(req, 0); 1088 if (unlikely(!__io_fill_cqe_req(ctx, req))) { 1089 spin_lock(&ctx->completion_lock); 1090 io_req_cqe_overflow(req); 1091 spin_unlock(&ctx->completion_lock); 1092 } 1093 } 1094 1095 if (unlikely(!nr_events)) 1096 return 0; 1097 1098 io_commit_cqring(ctx); 1099 io_cqring_ev_posted_iopoll(ctx); 1100 pos = start ? start->next : ctx->iopoll_list.first; 1101 wq_list_cut(&ctx->iopoll_list, prev, start); 1102 io_free_batch_list(ctx, pos); 1103 return nr_events; 1104 } 1105