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