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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/cmd.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 "poll.h"
22#include "rw.h"
23
24struct io_rw {
25 /* NOTE: kiocb has the file as the first member, so don't do it here */
26 struct kiocb kiocb;
27 u64 addr;
28 u32 len;
29 rwf_t flags;
30};
31
32static inline bool io_file_supports_nowait(struct io_kiocb *req)
33{
34 return req->flags & REQ_F_SUPPORT_NOWAIT;
35}
36
37#ifdef CONFIG_COMPAT
38static int io_iov_compat_buffer_select_prep(struct io_rw *rw)
39{
40 struct compat_iovec __user *uiov;
41 compat_ssize_t clen;
42
43 uiov = u64_to_user_ptr(rw->addr);
44 if (!access_ok(uiov, sizeof(*uiov)))
45 return -EFAULT;
46 if (__get_user(clen, &uiov->iov_len))
47 return -EFAULT;
48 if (clen < 0)
49 return -EINVAL;
50
51 rw->len = clen;
52 return 0;
53}
54#endif
55
56static int io_iov_buffer_select_prep(struct io_kiocb *req)
57{
58 struct iovec __user *uiov;
59 struct iovec iov;
60 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
61
62 if (rw->len != 1)
63 return -EINVAL;
64
65#ifdef CONFIG_COMPAT
66 if (req->ctx->compat)
67 return io_iov_compat_buffer_select_prep(rw);
68#endif
69
70 uiov = u64_to_user_ptr(rw->addr);
71 if (copy_from_user(&iov, uiov, sizeof(*uiov)))
72 return -EFAULT;
73 rw->len = iov.iov_len;
74 return 0;
75}
76
77int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
78{
79 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
80 unsigned ioprio;
81 int ret;
82
83 rw->kiocb.ki_pos = READ_ONCE(sqe->off);
84 /* used for fixed read/write too - just read unconditionally */
85 req->buf_index = READ_ONCE(sqe->buf_index);
86
87 ioprio = READ_ONCE(sqe->ioprio);
88 if (ioprio) {
89 ret = ioprio_check_cap(ioprio);
90 if (ret)
91 return ret;
92
93 rw->kiocb.ki_ioprio = ioprio;
94 } else {
95 rw->kiocb.ki_ioprio = get_current_ioprio();
96 }
97 rw->kiocb.dio_complete = NULL;
98
99 rw->addr = READ_ONCE(sqe->addr);
100 rw->len = READ_ONCE(sqe->len);
101 rw->flags = READ_ONCE(sqe->rw_flags);
102 return 0;
103}
104
105int io_prep_rwv(struct io_kiocb *req, const struct io_uring_sqe *sqe)
106{
107 int ret;
108
109 ret = io_prep_rw(req, sqe);
110 if (unlikely(ret))
111 return ret;
112
113 /*
114 * Have to do this validation here, as this is in io_read() rw->len
115 * might have chanaged due to buffer selection
116 */
117 if (req->flags & REQ_F_BUFFER_SELECT)
118 return io_iov_buffer_select_prep(req);
119
120 return 0;
121}
122
123int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
124{
125 struct io_ring_ctx *ctx = req->ctx;
126 u16 index;
127 int ret;
128
129 ret = io_prep_rw(req, sqe);
130 if (unlikely(ret))
131 return ret;
132
133 if (unlikely(req->buf_index >= ctx->nr_user_bufs))
134 return -EFAULT;
135 index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
136 req->imu = ctx->user_bufs[index];
137 io_req_set_rsrc_node(req, ctx, 0);
138 return 0;
139}
140
141/*
142 * Multishot read is prepared just like a normal read/write request, only
143 * difference is that we set the MULTISHOT flag.
144 */
145int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
146{
147 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
148 int ret;
149
150 /* must be used with provided buffers */
151 if (!(req->flags & REQ_F_BUFFER_SELECT))
152 return -EINVAL;
153
154 ret = io_prep_rw(req, sqe);
155 if (unlikely(ret))
156 return ret;
157
158 if (rw->addr || rw->len)
159 return -EINVAL;
160
161 req->flags |= REQ_F_APOLL_MULTISHOT;
162 return 0;
163}
164
165void io_readv_writev_cleanup(struct io_kiocb *req)
166{
167 struct io_async_rw *io = req->async_data;
168
169 kfree(io->free_iovec);
170}
171
172static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
173{
174 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
175
176 if (rw->kiocb.ki_pos != -1)
177 return &rw->kiocb.ki_pos;
178
179 if (!(req->file->f_mode & FMODE_STREAM)) {
180 req->flags |= REQ_F_CUR_POS;
181 rw->kiocb.ki_pos = req->file->f_pos;
182 return &rw->kiocb.ki_pos;
183 }
184
185 rw->kiocb.ki_pos = 0;
186 return NULL;
187}
188
189static void io_req_task_queue_reissue(struct io_kiocb *req)
190{
191 req->io_task_work.func = io_queue_iowq;
192 io_req_task_work_add(req);
193}
194
195#ifdef CONFIG_BLOCK
196static bool io_resubmit_prep(struct io_kiocb *req)
197{
198 struct io_async_rw *io = req->async_data;
199
200 if (!req_has_async_data(req))
201 return !io_req_prep_async(req);
202 iov_iter_restore(&io->s.iter, &io->s.iter_state);
203 return true;
204}
205
206static bool io_rw_should_reissue(struct io_kiocb *req)
207{
208 umode_t mode = file_inode(req->file)->i_mode;
209 struct io_ring_ctx *ctx = req->ctx;
210
211 if (!S_ISBLK(mode) && !S_ISREG(mode))
212 return false;
213 if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
214 !(ctx->flags & IORING_SETUP_IOPOLL)))
215 return false;
216 /*
217 * If ref is dying, we might be running poll reap from the exit work.
218 * Don't attempt to reissue from that path, just let it fail with
219 * -EAGAIN.
220 */
221 if (percpu_ref_is_dying(&ctx->refs))
222 return false;
223 /*
224 * Play it safe and assume not safe to re-import and reissue if we're
225 * not in the original thread group (or in task context).
226 */
227 if (!same_thread_group(req->task, current) || !in_task())
228 return false;
229 return true;
230}
231#else
232static bool io_resubmit_prep(struct io_kiocb *req)
233{
234 return false;
235}
236static bool io_rw_should_reissue(struct io_kiocb *req)
237{
238 return false;
239}
240#endif
241
242static void io_req_end_write(struct io_kiocb *req)
243{
244 if (req->flags & REQ_F_ISREG) {
245 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
246
247 kiocb_end_write(&rw->kiocb);
248 }
249}
250
251/*
252 * Trigger the notifications after having done some IO, and finish the write
253 * accounting, if any.
254 */
255static void io_req_io_end(struct io_kiocb *req)
256{
257 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
258
259 if (rw->kiocb.ki_flags & IOCB_WRITE) {
260 io_req_end_write(req);
261 fsnotify_modify(req->file);
262 } else {
263 fsnotify_access(req->file);
264 }
265}
266
267static bool __io_complete_rw_common(struct io_kiocb *req, long res)
268{
269 if (unlikely(res != req->cqe.res)) {
270 if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
271 io_rw_should_reissue(req)) {
272 /*
273 * Reissue will start accounting again, finish the
274 * current cycle.
275 */
276 io_req_io_end(req);
277 req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
278 return true;
279 }
280 req_set_fail(req);
281 req->cqe.res = res;
282 }
283 return false;
284}
285
286static inline int io_fixup_rw_res(struct io_kiocb *req, long res)
287{
288 struct io_async_rw *io = req->async_data;
289
290 /* add previously done IO, if any */
291 if (req_has_async_data(req) && io->bytes_done > 0) {
292 if (res < 0)
293 res = io->bytes_done;
294 else
295 res += io->bytes_done;
296 }
297 return res;
298}
299
300void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts)
301{
302 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
303 struct kiocb *kiocb = &rw->kiocb;
304
305 if ((kiocb->ki_flags & IOCB_DIO_CALLER_COMP) && kiocb->dio_complete) {
306 long res = kiocb->dio_complete(rw->kiocb.private);
307
308 io_req_set_res(req, io_fixup_rw_res(req, res), 0);
309 }
310
311 io_req_io_end(req);
312
313 if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
314 unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED;
315
316 req->cqe.flags |= io_put_kbuf(req, issue_flags);
317 }
318 io_req_task_complete(req, ts);
319}
320
321static void io_complete_rw(struct kiocb *kiocb, long res)
322{
323 struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
324 struct io_kiocb *req = cmd_to_io_kiocb(rw);
325
326 if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) {
327 if (__io_complete_rw_common(req, res))
328 return;
329 io_req_set_res(req, io_fixup_rw_res(req, res), 0);
330 }
331 req->io_task_work.func = io_req_rw_complete;
332 __io_req_task_work_add(req, IOU_F_TWQ_LAZY_WAKE);
333}
334
335static void io_complete_rw_iopoll(struct kiocb *kiocb, long res)
336{
337 struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
338 struct io_kiocb *req = cmd_to_io_kiocb(rw);
339
340 if (kiocb->ki_flags & IOCB_WRITE)
341 io_req_end_write(req);
342 if (unlikely(res != req->cqe.res)) {
343 if (res == -EAGAIN && io_rw_should_reissue(req)) {
344 req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
345 return;
346 }
347 req->cqe.res = res;
348 }
349
350 /* order with io_iopoll_complete() checking ->iopoll_completed */
351 smp_store_release(&req->iopoll_completed, 1);
352}
353
354static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
355{
356 /* IO was queued async, completion will happen later */
357 if (ret == -EIOCBQUEUED)
358 return;
359
360 /* transform internal restart error codes */
361 if (unlikely(ret < 0)) {
362 switch (ret) {
363 case -ERESTARTSYS:
364 case -ERESTARTNOINTR:
365 case -ERESTARTNOHAND:
366 case -ERESTART_RESTARTBLOCK:
367 /*
368 * We can't just restart the syscall, since previously
369 * submitted sqes may already be in progress. Just fail
370 * this IO with EINTR.
371 */
372 ret = -EINTR;
373 break;
374 }
375 }
376
377 INDIRECT_CALL_2(kiocb->ki_complete, io_complete_rw_iopoll,
378 io_complete_rw, kiocb, ret);
379}
380
381static int kiocb_done(struct io_kiocb *req, ssize_t ret,
382 unsigned int issue_flags)
383{
384 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
385 unsigned final_ret = io_fixup_rw_res(req, ret);
386
387 if (ret >= 0 && req->flags & REQ_F_CUR_POS)
388 req->file->f_pos = rw->kiocb.ki_pos;
389 if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) {
390 if (!__io_complete_rw_common(req, ret)) {
391 /*
392 * Safe to call io_end from here as we're inline
393 * from the submission path.
394 */
395 io_req_io_end(req);
396 io_req_set_res(req, final_ret,
397 io_put_kbuf(req, issue_flags));
398 return IOU_OK;
399 }
400 } else {
401 io_rw_done(&rw->kiocb, ret);
402 }
403
404 if (req->flags & REQ_F_REISSUE) {
405 req->flags &= ~REQ_F_REISSUE;
406 if (io_resubmit_prep(req))
407 io_req_task_queue_reissue(req);
408 else
409 io_req_task_queue_fail(req, final_ret);
410 }
411 return IOU_ISSUE_SKIP_COMPLETE;
412}
413
414static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
415 struct io_rw_state *s,
416 unsigned int issue_flags)
417{
418 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
419 struct iov_iter *iter = &s->iter;
420 u8 opcode = req->opcode;
421 struct iovec *iovec;
422 void __user *buf;
423 size_t sqe_len;
424 ssize_t ret;
425
426 if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
427 ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len);
428 if (ret)
429 return ERR_PTR(ret);
430 return NULL;
431 }
432
433 buf = u64_to_user_ptr(rw->addr);
434 sqe_len = rw->len;
435
436 if (!io_issue_defs[opcode].vectored || req->flags & REQ_F_BUFFER_SELECT) {
437 if (io_do_buffer_select(req)) {
438 buf = io_buffer_select(req, &sqe_len, issue_flags);
439 if (!buf)
440 return ERR_PTR(-ENOBUFS);
441 rw->addr = (unsigned long) buf;
442 rw->len = sqe_len;
443 }
444
445 ret = import_ubuf(ddir, buf, sqe_len, iter);
446 if (ret)
447 return ERR_PTR(ret);
448 return NULL;
449 }
450
451 iovec = s->fast_iov;
452 ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter,
453 req->ctx->compat);
454 if (unlikely(ret < 0))
455 return ERR_PTR(ret);
456 return iovec;
457}
458
459static inline int io_import_iovec(int rw, struct io_kiocb *req,
460 struct iovec **iovec, struct io_rw_state *s,
461 unsigned int issue_flags)
462{
463 *iovec = __io_import_iovec(rw, req, s, issue_flags);
464 if (IS_ERR(*iovec))
465 return PTR_ERR(*iovec);
466
467 iov_iter_save_state(&s->iter, &s->iter_state);
468 return 0;
469}
470
471static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
472{
473 return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos;
474}
475
476/*
477 * For files that don't have ->read_iter() and ->write_iter(), handle them
478 * by looping over ->read() or ->write() manually.
479 */
480static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
481{
482 struct kiocb *kiocb = &rw->kiocb;
483 struct file *file = kiocb->ki_filp;
484 ssize_t ret = 0;
485 loff_t *ppos;
486
487 /*
488 * Don't support polled IO through this interface, and we can't
489 * support non-blocking either. For the latter, this just causes
490 * the kiocb to be handled from an async context.
491 */
492 if (kiocb->ki_flags & IOCB_HIPRI)
493 return -EOPNOTSUPP;
494 if ((kiocb->ki_flags & IOCB_NOWAIT) &&
495 !(kiocb->ki_filp->f_flags & O_NONBLOCK))
496 return -EAGAIN;
497
498 ppos = io_kiocb_ppos(kiocb);
499
500 while (iov_iter_count(iter)) {
501 void __user *addr;
502 size_t len;
503 ssize_t nr;
504
505 if (iter_is_ubuf(iter)) {
506 addr = iter->ubuf + iter->iov_offset;
507 len = iov_iter_count(iter);
508 } else if (!iov_iter_is_bvec(iter)) {
509 addr = iter_iov_addr(iter);
510 len = iter_iov_len(iter);
511 } else {
512 addr = u64_to_user_ptr(rw->addr);
513 len = rw->len;
514 }
515
516 if (ddir == READ)
517 nr = file->f_op->read(file, addr, len, ppos);
518 else
519 nr = file->f_op->write(file, addr, len, ppos);
520
521 if (nr < 0) {
522 if (!ret)
523 ret = nr;
524 break;
525 }
526 ret += nr;
527 if (!iov_iter_is_bvec(iter)) {
528 iov_iter_advance(iter, nr);
529 } else {
530 rw->addr += nr;
531 rw->len -= nr;
532 if (!rw->len)
533 break;
534 }
535 if (nr != len)
536 break;
537 }
538
539 return ret;
540}
541
542static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
543 const struct iovec *fast_iov, struct iov_iter *iter)
544{
545 struct io_async_rw *io = req->async_data;
546
547 memcpy(&io->s.iter, iter, sizeof(*iter));
548 io->free_iovec = iovec;
549 io->bytes_done = 0;
550 /* can only be fixed buffers, no need to do anything */
551 if (iov_iter_is_bvec(iter) || iter_is_ubuf(iter))
552 return;
553 if (!iovec) {
554 unsigned iov_off = 0;
555
556 io->s.iter.__iov = io->s.fast_iov;
557 if (iter->__iov != fast_iov) {
558 iov_off = iter_iov(iter) - fast_iov;
559 io->s.iter.__iov += iov_off;
560 }
561 if (io->s.fast_iov != fast_iov)
562 memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off,
563 sizeof(struct iovec) * iter->nr_segs);
564 } else {
565 req->flags |= REQ_F_NEED_CLEANUP;
566 }
567}
568
569static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
570 struct io_rw_state *s, bool force)
571{
572 if (!force && !io_cold_defs[req->opcode].prep_async)
573 return 0;
574 /* opcode type doesn't need async data */
575 if (!io_cold_defs[req->opcode].async_size)
576 return 0;
577 if (!req_has_async_data(req)) {
578 struct io_async_rw *iorw;
579
580 if (io_alloc_async_data(req)) {
581 kfree(iovec);
582 return -ENOMEM;
583 }
584
585 io_req_map_rw(req, iovec, s->fast_iov, &s->iter);
586 iorw = req->async_data;
587 /* we've copied and mapped the iter, ensure state is saved */
588 iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state);
589 }
590 return 0;
591}
592
593static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
594{
595 struct io_async_rw *iorw = req->async_data;
596 struct iovec *iov;
597 int ret;
598
599 iorw->bytes_done = 0;
600 iorw->free_iovec = NULL;
601
602 /* submission path, ->uring_lock should already be taken */
603 ret = io_import_iovec(rw, req, &iov, &iorw->s, 0);
604 if (unlikely(ret < 0))
605 return ret;
606
607 if (iov) {
608 iorw->free_iovec = iov;
609 req->flags |= REQ_F_NEED_CLEANUP;
610 }
611
612 return 0;
613}
614
615int io_readv_prep_async(struct io_kiocb *req)
616{
617 return io_rw_prep_async(req, ITER_DEST);
618}
619
620int io_writev_prep_async(struct io_kiocb *req)
621{
622 return io_rw_prep_async(req, ITER_SOURCE);
623}
624
625/*
626 * This is our waitqueue callback handler, registered through __folio_lock_async()
627 * when we initially tried to do the IO with the iocb armed our waitqueue.
628 * This gets called when the page is unlocked, and we generally expect that to
629 * happen when the page IO is completed and the page is now uptodate. This will
630 * queue a task_work based retry of the operation, attempting to copy the data
631 * again. If the latter fails because the page was NOT uptodate, then we will
632 * do a thread based blocking retry of the operation. That's the unexpected
633 * slow path.
634 */
635static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
636 int sync, void *arg)
637{
638 struct wait_page_queue *wpq;
639 struct io_kiocb *req = wait->private;
640 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
641 struct wait_page_key *key = arg;
642
643 wpq = container_of(wait, struct wait_page_queue, wait);
644
645 if (!wake_page_match(wpq, key))
646 return 0;
647
648 rw->kiocb.ki_flags &= ~IOCB_WAITQ;
649 list_del_init(&wait->entry);
650 io_req_task_queue(req);
651 return 1;
652}
653
654/*
655 * This controls whether a given IO request should be armed for async page
656 * based retry. If we return false here, the request is handed to the async
657 * worker threads for retry. If we're doing buffered reads on a regular file,
658 * we prepare a private wait_page_queue entry and retry the operation. This
659 * will either succeed because the page is now uptodate and unlocked, or it
660 * will register a callback when the page is unlocked at IO completion. Through
661 * that callback, io_uring uses task_work to setup a retry of the operation.
662 * That retry will attempt the buffered read again. The retry will generally
663 * succeed, or in rare cases where it fails, we then fall back to using the
664 * async worker threads for a blocking retry.
665 */
666static bool io_rw_should_retry(struct io_kiocb *req)
667{
668 struct io_async_rw *io = req->async_data;
669 struct wait_page_queue *wait = &io->wpq;
670 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
671 struct kiocb *kiocb = &rw->kiocb;
672
673 /* never retry for NOWAIT, we just complete with -EAGAIN */
674 if (req->flags & REQ_F_NOWAIT)
675 return false;
676
677 /* Only for buffered IO */
678 if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI))
679 return false;
680
681 /*
682 * just use poll if we can, and don't attempt if the fs doesn't
683 * support callback based unlocks
684 */
685 if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC))
686 return false;
687
688 wait->wait.func = io_async_buf_func;
689 wait->wait.private = req;
690 wait->wait.flags = 0;
691 INIT_LIST_HEAD(&wait->wait.entry);
692 kiocb->ki_flags |= IOCB_WAITQ;
693 kiocb->ki_flags &= ~IOCB_NOWAIT;
694 kiocb->ki_waitq = wait;
695 return true;
696}
697
698static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter)
699{
700 struct file *file = rw->kiocb.ki_filp;
701
702 if (likely(file->f_op->read_iter))
703 return call_read_iter(file, &rw->kiocb, iter);
704 else if (file->f_op->read)
705 return loop_rw_iter(READ, rw, iter);
706 else
707 return -EINVAL;
708}
709
710static bool need_complete_io(struct io_kiocb *req)
711{
712 return req->flags & REQ_F_ISREG ||
713 S_ISBLK(file_inode(req->file)->i_mode);
714}
715
716static int io_rw_init_file(struct io_kiocb *req, fmode_t mode)
717{
718 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
719 struct kiocb *kiocb = &rw->kiocb;
720 struct io_ring_ctx *ctx = req->ctx;
721 struct file *file = req->file;
722 int ret;
723
724 if (unlikely(!file || !(file->f_mode & mode)))
725 return -EBADF;
726
727 if (!(req->flags & REQ_F_FIXED_FILE))
728 req->flags |= io_file_get_flags(file);
729
730 kiocb->ki_flags = file->f_iocb_flags;
731 ret = kiocb_set_rw_flags(kiocb, rw->flags);
732 if (unlikely(ret))
733 return ret;
734 kiocb->ki_flags |= IOCB_ALLOC_CACHE;
735
736 /*
737 * If the file is marked O_NONBLOCK, still allow retry for it if it
738 * supports async. Otherwise it's impossible to use O_NONBLOCK files
739 * reliably. If not, or it IOCB_NOWAIT is set, don't retry.
740 */
741 if ((kiocb->ki_flags & IOCB_NOWAIT) ||
742 ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req)))
743 req->flags |= REQ_F_NOWAIT;
744
745 if (ctx->flags & IORING_SETUP_IOPOLL) {
746 if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll)
747 return -EOPNOTSUPP;
748
749 kiocb->private = NULL;
750 kiocb->ki_flags |= IOCB_HIPRI;
751 kiocb->ki_complete = io_complete_rw_iopoll;
752 req->iopoll_completed = 0;
753 } else {
754 if (kiocb->ki_flags & IOCB_HIPRI)
755 return -EINVAL;
756 kiocb->ki_complete = io_complete_rw;
757 }
758
759 return 0;
760}
761
762static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
763{
764 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
765 struct io_rw_state __s, *s = &__s;
766 struct iovec *iovec;
767 struct kiocb *kiocb = &rw->kiocb;
768 bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
769 struct io_async_rw *io;
770 ssize_t ret, ret2;
771 loff_t *ppos;
772
773 if (!req_has_async_data(req)) {
774 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
775 if (unlikely(ret < 0))
776 return ret;
777 } else {
778 io = req->async_data;
779 s = &io->s;
780
781 /*
782 * Safe and required to re-import if we're using provided
783 * buffers, as we dropped the selected one before retry.
784 */
785 if (io_do_buffer_select(req)) {
786 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
787 if (unlikely(ret < 0))
788 return ret;
789 }
790
791 /*
792 * We come here from an earlier attempt, restore our state to
793 * match in case it doesn't. It's cheap enough that we don't
794 * need to make this conditional.
795 */
796 iov_iter_restore(&s->iter, &s->iter_state);
797 iovec = NULL;
798 }
799 ret = io_rw_init_file(req, FMODE_READ);
800 if (unlikely(ret)) {
801 kfree(iovec);
802 return ret;
803 }
804 req->cqe.res = iov_iter_count(&s->iter);
805
806 if (force_nonblock) {
807 /* If the file doesn't support async, just async punt */
808 if (unlikely(!io_file_supports_nowait(req))) {
809 ret = io_setup_async_rw(req, iovec, s, true);
810 return ret ?: -EAGAIN;
811 }
812 kiocb->ki_flags |= IOCB_NOWAIT;
813 } else {
814 /* Ensure we clear previously set non-block flag */
815 kiocb->ki_flags &= ~IOCB_NOWAIT;
816 }
817
818 ppos = io_kiocb_update_pos(req);
819
820 ret = rw_verify_area(READ, req->file, ppos, req->cqe.res);
821 if (unlikely(ret)) {
822 kfree(iovec);
823 return ret;
824 }
825
826 ret = io_iter_do_read(rw, &s->iter);
827
828 if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
829 req->flags &= ~REQ_F_REISSUE;
830 /*
831 * If we can poll, just do that. For a vectored read, we'll
832 * need to copy state first.
833 */
834 if (file_can_poll(req->file) && !io_issue_defs[req->opcode].vectored)
835 return -EAGAIN;
836 /* IOPOLL retry should happen for io-wq threads */
837 if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
838 goto done;
839 /* no retry on NONBLOCK nor RWF_NOWAIT */
840 if (req->flags & REQ_F_NOWAIT)
841 goto done;
842 ret = 0;
843 } else if (ret == -EIOCBQUEUED) {
844 if (iovec)
845 kfree(iovec);
846 return IOU_ISSUE_SKIP_COMPLETE;
847 } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
848 (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
849 /* read all, failed, already did sync or don't want to retry */
850 goto done;
851 }
852
853 /*
854 * Don't depend on the iter state matching what was consumed, or being
855 * untouched in case of error. Restore it and we'll advance it
856 * manually if we need to.
857 */
858 iov_iter_restore(&s->iter, &s->iter_state);
859
860 ret2 = io_setup_async_rw(req, iovec, s, true);
861 iovec = NULL;
862 if (ret2) {
863 ret = ret > 0 ? ret : ret2;
864 goto done;
865 }
866
867 io = req->async_data;
868 s = &io->s;
869 /*
870 * Now use our persistent iterator and state, if we aren't already.
871 * We've restored and mapped the iter to match.
872 */
873
874 do {
875 /*
876 * We end up here because of a partial read, either from
877 * above or inside this loop. Advance the iter by the bytes
878 * that were consumed.
879 */
880 iov_iter_advance(&s->iter, ret);
881 if (!iov_iter_count(&s->iter))
882 break;
883 io->bytes_done += ret;
884 iov_iter_save_state(&s->iter, &s->iter_state);
885
886 /* if we can retry, do so with the callbacks armed */
887 if (!io_rw_should_retry(req)) {
888 kiocb->ki_flags &= ~IOCB_WAITQ;
889 return -EAGAIN;
890 }
891
892 req->cqe.res = iov_iter_count(&s->iter);
893 /*
894 * Now retry read with the IOCB_WAITQ parts set in the iocb. If
895 * we get -EIOCBQUEUED, then we'll get a notification when the
896 * desired page gets unlocked. We can also get a partial read
897 * here, and if we do, then just retry at the new offset.
898 */
899 ret = io_iter_do_read(rw, &s->iter);
900 if (ret == -EIOCBQUEUED)
901 return IOU_ISSUE_SKIP_COMPLETE;
902 /* we got some bytes, but not all. retry. */
903 kiocb->ki_flags &= ~IOCB_WAITQ;
904 iov_iter_restore(&s->iter, &s->iter_state);
905 } while (ret > 0);
906done:
907 /* it's faster to check here then delegate to kfree */
908 if (iovec)
909 kfree(iovec);
910 return ret;
911}
912
913int io_read(struct io_kiocb *req, unsigned int issue_flags)
914{
915 int ret;
916
917 ret = __io_read(req, issue_flags);
918 if (ret >= 0)
919 return kiocb_done(req, ret, issue_flags);
920
921 return ret;
922}
923
924int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
925{
926 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
927 unsigned int cflags = 0;
928 int ret;
929
930 /*
931 * Multishot MUST be used on a pollable file
932 */
933 if (!file_can_poll(req->file))
934 return -EBADFD;
935
936 ret = __io_read(req, issue_flags);
937
938 /*
939 * If we get -EAGAIN, recycle our buffer and just let normal poll
940 * handling arm it.
941 */
942 if (ret == -EAGAIN) {
943 /*
944 * Reset rw->len to 0 again to avoid clamping future mshot
945 * reads, in case the buffer size varies.
946 */
947 if (io_kbuf_recycle(req, issue_flags))
948 rw->len = 0;
949 return -EAGAIN;
950 }
951
952 /*
953 * Any successful return value will keep the multishot read armed.
954 */
955 if (ret > 0) {
956 /*
957 * Put our buffer and post a CQE. If we fail to post a CQE, then
958 * jump to the termination path. This request is then done.
959 */
960 cflags = io_put_kbuf(req, issue_flags);
961 rw->len = 0; /* similarly to above, reset len to 0 */
962
963 if (io_fill_cqe_req_aux(req,
964 issue_flags & IO_URING_F_COMPLETE_DEFER,
965 ret, cflags | IORING_CQE_F_MORE)) {
966 if (issue_flags & IO_URING_F_MULTISHOT) {
967 /*
968 * Force retry, as we might have more data to
969 * be read and otherwise it won't get retried
970 * until (if ever) another poll is triggered.
971 */
972 io_poll_multishot_retry(req);
973 return IOU_ISSUE_SKIP_COMPLETE;
974 }
975 return -EAGAIN;
976 }
977 }
978
979 /*
980 * Either an error, or we've hit overflow posting the CQE. For any
981 * multishot request, hitting overflow will terminate it.
982 */
983 io_req_set_res(req, ret, cflags);
984 if (issue_flags & IO_URING_F_MULTISHOT)
985 return IOU_STOP_MULTISHOT;
986 return IOU_OK;
987}
988
989int io_write(struct io_kiocb *req, unsigned int issue_flags)
990{
991 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
992 struct io_rw_state __s, *s = &__s;
993 struct iovec *iovec;
994 struct kiocb *kiocb = &rw->kiocb;
995 bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
996 ssize_t ret, ret2;
997 loff_t *ppos;
998
999 if (!req_has_async_data(req)) {
1000 ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags);
1001 if (unlikely(ret < 0))
1002 return ret;
1003 } else {
1004 struct io_async_rw *io = req->async_data;
1005
1006 s = &io->s;
1007 iov_iter_restore(&s->iter, &s->iter_state);
1008 iovec = NULL;
1009 }
1010 ret = io_rw_init_file(req, FMODE_WRITE);
1011 if (unlikely(ret)) {
1012 kfree(iovec);
1013 return ret;
1014 }
1015 req->cqe.res = iov_iter_count(&s->iter);
1016
1017 if (force_nonblock) {
1018 /* If the file doesn't support async, just async punt */
1019 if (unlikely(!io_file_supports_nowait(req)))
1020 goto copy_iov;
1021
1022 /* File path supports NOWAIT for non-direct_IO only for block devices. */
1023 if (!(kiocb->ki_flags & IOCB_DIRECT) &&
1024 !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) &&
1025 (req->flags & REQ_F_ISREG))
1026 goto copy_iov;
1027
1028 kiocb->ki_flags |= IOCB_NOWAIT;
1029 } else {
1030 /* Ensure we clear previously set non-block flag */
1031 kiocb->ki_flags &= ~IOCB_NOWAIT;
1032 }
1033
1034 ppos = io_kiocb_update_pos(req);
1035
1036 ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res);
1037 if (unlikely(ret)) {
1038 kfree(iovec);
1039 return ret;
1040 }
1041
1042 if (req->flags & REQ_F_ISREG)
1043 kiocb_start_write(kiocb);
1044 kiocb->ki_flags |= IOCB_WRITE;
1045
1046 if (likely(req->file->f_op->write_iter))
1047 ret2 = call_write_iter(req->file, kiocb, &s->iter);
1048 else if (req->file->f_op->write)
1049 ret2 = loop_rw_iter(WRITE, rw, &s->iter);
1050 else
1051 ret2 = -EINVAL;
1052
1053 if (req->flags & REQ_F_REISSUE) {
1054 req->flags &= ~REQ_F_REISSUE;
1055 ret2 = -EAGAIN;
1056 }
1057
1058 /*
1059 * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
1060 * retry them without IOCB_NOWAIT.
1061 */
1062 if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT))
1063 ret2 = -EAGAIN;
1064 /* no retry on NONBLOCK nor RWF_NOWAIT */
1065 if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
1066 goto done;
1067 if (!force_nonblock || ret2 != -EAGAIN) {
1068 /* IOPOLL retry should happen for io-wq threads */
1069 if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
1070 goto copy_iov;
1071
1072 if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
1073 struct io_async_rw *io;
1074
1075 trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
1076 req->cqe.res, ret2);
1077
1078 /* This is a partial write. The file pos has already been
1079 * updated, setup the async struct to complete the request
1080 * in the worker. Also update bytes_done to account for
1081 * the bytes already written.
1082 */
1083 iov_iter_save_state(&s->iter, &s->iter_state);
1084 ret = io_setup_async_rw(req, iovec, s, true);
1085
1086 io = req->async_data;
1087 if (io)
1088 io->bytes_done += ret2;
1089
1090 if (kiocb->ki_flags & IOCB_WRITE)
1091 io_req_end_write(req);
1092 return ret ? ret : -EAGAIN;
1093 }
1094done:
1095 ret = kiocb_done(req, ret2, issue_flags);
1096 } else {
1097copy_iov:
1098 iov_iter_restore(&s->iter, &s->iter_state);
1099 ret = io_setup_async_rw(req, iovec, s, false);
1100 if (!ret) {
1101 if (kiocb->ki_flags & IOCB_WRITE)
1102 io_req_end_write(req);
1103 return -EAGAIN;
1104 }
1105 return ret;
1106 }
1107 /* it's reportedly faster than delegating the null check to kfree() */
1108 if (iovec)
1109 kfree(iovec);
1110 return ret;
1111}
1112
1113void io_rw_fail(struct io_kiocb *req)
1114{
1115 int res;
1116
1117 res = io_fixup_rw_res(req, req->cqe.res);
1118 io_req_set_res(req, res, req->cqe.flags);
1119}
1120
1121int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
1122{
1123 struct io_wq_work_node *pos, *start, *prev;
1124 unsigned int poll_flags = 0;
1125 DEFINE_IO_COMP_BATCH(iob);
1126 int nr_events = 0;
1127
1128 /*
1129 * Only spin for completions if we don't have multiple devices hanging
1130 * off our complete list.
1131 */
1132 if (ctx->poll_multi_queue || force_nonspin)
1133 poll_flags |= BLK_POLL_ONESHOT;
1134
1135 wq_list_for_each(pos, start, &ctx->iopoll_list) {
1136 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
1137 struct file *file = req->file;
1138 int ret;
1139
1140 /*
1141 * Move completed and retryable entries to our local lists.
1142 * If we find a request that requires polling, break out
1143 * and complete those lists first, if we have entries there.
1144 */
1145 if (READ_ONCE(req->iopoll_completed))
1146 break;
1147
1148 if (req->opcode == IORING_OP_URING_CMD) {
1149 struct io_uring_cmd *ioucmd;
1150
1151 ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
1152 ret = file->f_op->uring_cmd_iopoll(ioucmd, &iob,
1153 poll_flags);
1154 } else {
1155 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
1156
1157 ret = file->f_op->iopoll(&rw->kiocb, &iob, poll_flags);
1158 }
1159 if (unlikely(ret < 0))
1160 return ret;
1161 else if (ret)
1162 poll_flags |= BLK_POLL_ONESHOT;
1163
1164 /* iopoll may have completed current req */
1165 if (!rq_list_empty(iob.req_list) ||
1166 READ_ONCE(req->iopoll_completed))
1167 break;
1168 }
1169
1170 if (!rq_list_empty(iob.req_list))
1171 iob.complete(&iob);
1172 else if (!pos)
1173 return 0;
1174
1175 prev = start;
1176 wq_list_for_each_resume(pos, prev) {
1177 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
1178
1179 /* order with io_complete_rw_iopoll(), e.g. ->result updates */
1180 if (!smp_load_acquire(&req->iopoll_completed))
1181 break;
1182 nr_events++;
1183 req->cqe.flags = io_put_kbuf(req, 0);
1184 }
1185 if (unlikely(!nr_events))
1186 return 0;
1187
1188 pos = start ? start->next : ctx->iopoll_list.first;
1189 wq_list_cut(&ctx->iopoll_list, prev, start);
1190
1191 if (WARN_ON_ONCE(!wq_list_empty(&ctx->submit_state.compl_reqs)))
1192 return 0;
1193 ctx->submit_state.compl_reqs.first = pos;
1194 __io_submit_flush_completions(ctx);
1195 return nr_events;
1196}