1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (c) 2016-2025 Christoph Hellwig.
5 */
6 #include <linux/fscrypt.h>
7 #include <linux/pagemap.h>
8 #include <linux/iomap.h>
9 #include <linux/task_io_accounting_ops.h>
10 #include "internal.h"
11 #include "trace.h"
12
13 #include "../internal.h"
14
15 /*
16 * Private flags for iomap_dio, must not overlap with the public ones in
17 * iomap.h:
18 */
19 #define IOMAP_DIO_NO_INVALIDATE (1U << 26)
20 #define IOMAP_DIO_COMP_WORK (1U << 27)
21 #define IOMAP_DIO_WRITE_THROUGH (1U << 28)
22 #define IOMAP_DIO_NEED_SYNC (1U << 29)
23 #define IOMAP_DIO_WRITE (1U << 30)
24 #define IOMAP_DIO_DIRTY (1U << 31)
25
26 struct iomap_dio {
27 struct kiocb *iocb;
28 const struct iomap_dio_ops *dops;
29 loff_t i_size;
30 loff_t size;
31 atomic_t ref;
32 unsigned flags;
33 int error;
34 size_t done_before;
35 bool wait_for_completion;
36
37 union {
38 /* used during submission and for synchronous completion: */
39 struct {
40 struct iov_iter *iter;
41 struct task_struct *waiter;
42 } submit;
43
44 /* used for aio completion: */
45 struct {
46 struct work_struct work;
47 } aio;
48 };
49 };
50
iomap_dio_alloc_bio(const struct iomap_iter * iter,struct iomap_dio * dio,unsigned short nr_vecs,blk_opf_t opf)51 static struct bio *iomap_dio_alloc_bio(const struct iomap_iter *iter,
52 struct iomap_dio *dio, unsigned short nr_vecs, blk_opf_t opf)
53 {
54 if (dio->dops && dio->dops->bio_set)
55 return bio_alloc_bioset(iter->iomap.bdev, nr_vecs, opf,
56 GFP_KERNEL, dio->dops->bio_set);
57 return bio_alloc(iter->iomap.bdev, nr_vecs, opf, GFP_KERNEL);
58 }
59
iomap_dio_submit_bio(const struct iomap_iter * iter,struct iomap_dio * dio,struct bio * bio,loff_t pos)60 static void iomap_dio_submit_bio(const struct iomap_iter *iter,
61 struct iomap_dio *dio, struct bio *bio, loff_t pos)
62 {
63 struct kiocb *iocb = dio->iocb;
64
65 atomic_inc(&dio->ref);
66
67 /* Sync dio can't be polled reliably */
68 if ((iocb->ki_flags & IOCB_HIPRI) && !is_sync_kiocb(iocb)) {
69 bio_set_polled(bio, iocb);
70 WRITE_ONCE(iocb->private, bio);
71 }
72
73 if (dio->dops && dio->dops->submit_io) {
74 dio->dops->submit_io(iter, bio, pos);
75 } else {
76 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_ANON_WRITE);
77 submit_bio(bio);
78 }
79 }
80
iomap_dio_complete(struct iomap_dio * dio)81 ssize_t iomap_dio_complete(struct iomap_dio *dio)
82 {
83 const struct iomap_dio_ops *dops = dio->dops;
84 struct kiocb *iocb = dio->iocb;
85 loff_t offset = iocb->ki_pos;
86 ssize_t ret = dio->error;
87
88 if (dops && dops->end_io)
89 ret = dops->end_io(iocb, dio->size, ret, dio->flags);
90
91 if (likely(!ret)) {
92 ret = dio->size;
93 /* check for short read */
94 if (offset + ret > dio->i_size &&
95 !(dio->flags & IOMAP_DIO_WRITE))
96 ret = dio->i_size - offset;
97 }
98
99 /*
100 * Try again to invalidate clean pages which might have been cached by
101 * non-direct readahead, or faulted in by get_user_pages() if the source
102 * of the write was an mmap'ed region of the file we're writing. Either
103 * one is a pretty crazy thing to do, so we don't support it 100%. If
104 * this invalidation fails, tough, the write still worked...
105 *
106 * And this page cache invalidation has to be after ->end_io(), as some
107 * filesystems convert unwritten extents to real allocations in
108 * ->end_io() when necessary, otherwise a racing buffer read would cache
109 * zeros from unwritten extents.
110 */
111 if (!dio->error && dio->size && (dio->flags & IOMAP_DIO_WRITE) &&
112 !(dio->flags & IOMAP_DIO_NO_INVALIDATE))
113 kiocb_invalidate_post_direct_write(iocb, dio->size);
114
115 inode_dio_end(file_inode(iocb->ki_filp));
116
117 if (ret > 0) {
118 iocb->ki_pos += ret;
119
120 /*
121 * If this is a DSYNC write, make sure we push it to stable
122 * storage now that we've written data.
123 */
124 if (dio->flags & IOMAP_DIO_NEED_SYNC)
125 ret = generic_write_sync(iocb, ret);
126 if (ret > 0)
127 ret += dio->done_before;
128 }
129 trace_iomap_dio_complete(iocb, dio->error, ret);
130 kfree(dio);
131 return ret;
132 }
133 EXPORT_SYMBOL_GPL(iomap_dio_complete);
134
iomap_dio_complete_work(struct work_struct * work)135 static void iomap_dio_complete_work(struct work_struct *work)
136 {
137 struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
138 struct kiocb *iocb = dio->iocb;
139
140 iocb->ki_complete(iocb, iomap_dio_complete(dio));
141 }
142
143 /*
144 * Set an error in the dio if none is set yet. We have to use cmpxchg
145 * as the submission context and the completion context(s) can race to
146 * update the error.
147 */
iomap_dio_set_error(struct iomap_dio * dio,int ret)148 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
149 {
150 cmpxchg(&dio->error, 0, ret);
151 }
152
153 /*
154 * Called when dio->ref reaches zero from an I/O completion.
155 */
iomap_dio_done(struct iomap_dio * dio)156 static void iomap_dio_done(struct iomap_dio *dio)
157 {
158 struct kiocb *iocb = dio->iocb;
159
160 if (dio->wait_for_completion) {
161 /*
162 * Synchronous I/O, task itself will handle any completion work
163 * that needs after IO. All we need to do is wake the task.
164 */
165 struct task_struct *waiter = dio->submit.waiter;
166
167 WRITE_ONCE(dio->submit.waiter, NULL);
168 blk_wake_io_task(waiter);
169 return;
170 }
171
172 /*
173 * Always run error completions in user context. These are not
174 * performance critical and some code relies on taking sleeping locks
175 * for error handling.
176 */
177 if (dio->error)
178 dio->flags |= IOMAP_DIO_COMP_WORK;
179
180 /*
181 * Never invalidate pages from this context to avoid deadlocks with
182 * buffered I/O completions when called from the ioend workqueue,
183 * or avoid sleeping when called directly from ->bi_end_io.
184 * Tough luck if you hit the tiny race with someone dirtying the range
185 * right between this check and the actual completion.
186 */
187 if ((dio->flags & IOMAP_DIO_WRITE) &&
188 !(dio->flags & IOMAP_DIO_COMP_WORK)) {
189 if (dio->iocb->ki_filp->f_mapping->nrpages)
190 dio->flags |= IOMAP_DIO_COMP_WORK;
191 else
192 dio->flags |= IOMAP_DIO_NO_INVALIDATE;
193 }
194
195 if (dio->flags & IOMAP_DIO_COMP_WORK) {
196 struct inode *inode = file_inode(iocb->ki_filp);
197
198 /*
199 * Async DIO completion that requires filesystem level
200 * completion work gets punted to a work queue to complete as
201 * the operation may require more IO to be issued to finalise
202 * filesystem metadata changes or guarantee data integrity.
203 */
204 INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
205 queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
206 return;
207 }
208
209 WRITE_ONCE(iocb->private, NULL);
210 iomap_dio_complete_work(&dio->aio.work);
211 }
212
iomap_dio_bio_end_io(struct bio * bio)213 void iomap_dio_bio_end_io(struct bio *bio)
214 {
215 struct iomap_dio *dio = bio->bi_private;
216 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
217
218 if (bio->bi_status)
219 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
220
221 if (atomic_dec_and_test(&dio->ref))
222 iomap_dio_done(dio);
223
224 if (should_dirty) {
225 bio_check_pages_dirty(bio);
226 } else {
227 bio_release_pages(bio, false);
228 bio_put(bio);
229 }
230 }
231 EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io);
232
iomap_finish_ioend_direct(struct iomap_ioend * ioend)233 u32 iomap_finish_ioend_direct(struct iomap_ioend *ioend)
234 {
235 struct iomap_dio *dio = ioend->io_bio.bi_private;
236 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
237 u32 vec_count = ioend->io_bio.bi_vcnt;
238
239 if (ioend->io_error)
240 iomap_dio_set_error(dio, ioend->io_error);
241
242 if (atomic_dec_and_test(&dio->ref)) {
243 /*
244 * Try to avoid another context switch for the completion given
245 * that we are already called from the ioend completion
246 * workqueue.
247 */
248 dio->flags &= ~IOMAP_DIO_COMP_WORK;
249 iomap_dio_done(dio);
250 }
251
252 if (should_dirty) {
253 bio_check_pages_dirty(&ioend->io_bio);
254 } else {
255 bio_release_pages(&ioend->io_bio, false);
256 bio_put(&ioend->io_bio);
257 }
258
259 /*
260 * Return the number of bvecs completed as even direct I/O completions
261 * do significant per-folio work and we'll still want to give up the
262 * CPU after a lot of completions.
263 */
264 return vec_count;
265 }
266
iomap_dio_zero(const struct iomap_iter * iter,struct iomap_dio * dio,loff_t pos,unsigned len)267 static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
268 loff_t pos, unsigned len)
269 {
270 struct inode *inode = file_inode(dio->iocb->ki_filp);
271 struct bio *bio;
272 struct folio *zero_folio = largest_zero_folio();
273 int nr_vecs = max(1, i_blocksize(inode) / folio_size(zero_folio));
274
275 if (!len)
276 return 0;
277
278 /*
279 * This limit shall never be reached as most filesystems have a
280 * maximum blocksize of 64k.
281 */
282 if (WARN_ON_ONCE(nr_vecs > BIO_MAX_VECS))
283 return -EINVAL;
284
285 bio = iomap_dio_alloc_bio(iter, dio, nr_vecs,
286 REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
287 fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
288 GFP_KERNEL);
289 bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
290 bio->bi_private = dio;
291 bio->bi_end_io = iomap_dio_bio_end_io;
292
293 while (len > 0) {
294 unsigned int io_len = min(len, folio_size(zero_folio));
295
296 bio_add_folio_nofail(bio, zero_folio, io_len, 0);
297 len -= io_len;
298 }
299 iomap_dio_submit_bio(iter, dio, bio, pos);
300
301 return 0;
302 }
303
iomap_dio_bio_iter(struct iomap_iter * iter,struct iomap_dio * dio)304 static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
305 {
306 const struct iomap *iomap = &iter->iomap;
307 struct inode *inode = iter->inode;
308 unsigned int fs_block_size = i_blocksize(inode), pad;
309 const loff_t length = iomap_length(iter);
310 loff_t pos = iter->pos;
311 blk_opf_t bio_opf = REQ_SYNC | REQ_IDLE;
312 struct bio *bio;
313 bool need_zeroout = false;
314 int nr_pages, ret = 0;
315 u64 copied = 0;
316 size_t orig_count;
317 unsigned int alignment;
318
319 /*
320 * File systems that write out of place and always allocate new blocks
321 * need each bio to be block aligned as that's the unit of allocation.
322 */
323 if (dio->flags & IOMAP_DIO_FSBLOCK_ALIGNED)
324 alignment = fs_block_size;
325 else
326 alignment = bdev_logical_block_size(iomap->bdev);
327
328 if ((pos | length) & (alignment - 1))
329 return -EINVAL;
330
331 if (dio->flags & IOMAP_DIO_WRITE) {
332 bool need_completion_work = true;
333
334 switch (iomap->type) {
335 case IOMAP_MAPPED:
336 /*
337 * Directly mapped I/O does not inherently need to do
338 * work at I/O completion time. But there are various
339 * cases below where this will get set again.
340 */
341 need_completion_work = false;
342 break;
343 case IOMAP_UNWRITTEN:
344 dio->flags |= IOMAP_DIO_UNWRITTEN;
345 need_zeroout = true;
346 break;
347 default:
348 break;
349 }
350
351 if (iomap->flags & IOMAP_F_ATOMIC_BIO) {
352 /*
353 * Ensure that the mapping covers the full write
354 * length, otherwise it won't be submitted as a single
355 * bio, which is required to use hardware atomics.
356 */
357 if (length != iter->len)
358 return -EINVAL;
359 bio_opf |= REQ_ATOMIC;
360 }
361
362 if (iomap->flags & IOMAP_F_SHARED) {
363 /*
364 * Unsharing of needs to update metadata at I/O
365 * completion time.
366 */
367 need_completion_work = true;
368 dio->flags |= IOMAP_DIO_COW;
369 }
370
371 if (iomap->flags & IOMAP_F_NEW) {
372 /*
373 * Newly allocated blocks might need recording in
374 * metadata at I/O completion time.
375 */
376 need_completion_work = true;
377 need_zeroout = true;
378 }
379
380 /*
381 * Use a FUA write if we need datasync semantics and this is a
382 * pure overwrite that doesn't require any metadata updates.
383 *
384 * This allows us to avoid cache flushes on I/O completion.
385 */
386 if (dio->flags & IOMAP_DIO_WRITE_THROUGH) {
387 if (!need_completion_work &&
388 !(iomap->flags & IOMAP_F_DIRTY) &&
389 (!bdev_write_cache(iomap->bdev) ||
390 bdev_fua(iomap->bdev)))
391 bio_opf |= REQ_FUA;
392 else
393 dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
394 }
395
396 /*
397 * We can only do inline completion for pure overwrites that
398 * don't require additional I/O at completion time.
399 *
400 * This rules out writes that need zeroing or metdata updates to
401 * convert unwritten or shared extents.
402 *
403 * Writes that extend i_size are also not supported, but this is
404 * handled in __iomap_dio_rw().
405 */
406 if (need_completion_work)
407 dio->flags |= IOMAP_DIO_COMP_WORK;
408
409 bio_opf |= REQ_OP_WRITE;
410 } else {
411 bio_opf |= REQ_OP_READ;
412 }
413
414 /*
415 * Save the original count and trim the iter to just the extent we
416 * are operating on right now. The iter will be re-expanded once
417 * we are done.
418 */
419 orig_count = iov_iter_count(dio->submit.iter);
420 iov_iter_truncate(dio->submit.iter, length);
421
422 if (!iov_iter_count(dio->submit.iter))
423 goto out;
424
425 /*
426 * The rules for polled IO completions follow the guidelines as the
427 * ones we set for inline and deferred completions. If none of those
428 * are available for this IO, clear the polled flag.
429 */
430 if (dio->flags & IOMAP_DIO_COMP_WORK)
431 dio->iocb->ki_flags &= ~IOCB_HIPRI;
432
433 if (need_zeroout) {
434 /* zero out from the start of the block to the write offset */
435 pad = pos & (fs_block_size - 1);
436
437 ret = iomap_dio_zero(iter, dio, pos - pad, pad);
438 if (ret)
439 goto out;
440 }
441
442 nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
443 do {
444 size_t n;
445 if (dio->error) {
446 iov_iter_revert(dio->submit.iter, copied);
447 copied = ret = 0;
448 goto out;
449 }
450
451 bio = iomap_dio_alloc_bio(iter, dio, nr_pages, bio_opf);
452 fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
453 GFP_KERNEL);
454 bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
455 bio->bi_write_hint = inode->i_write_hint;
456 bio->bi_ioprio = dio->iocb->ki_ioprio;
457 bio->bi_private = dio;
458 bio->bi_end_io = iomap_dio_bio_end_io;
459
460 ret = bio_iov_iter_get_pages(bio, dio->submit.iter,
461 alignment - 1);
462 if (unlikely(ret)) {
463 /*
464 * We have to stop part way through an IO. We must fall
465 * through to the sub-block tail zeroing here, otherwise
466 * this short IO may expose stale data in the tail of
467 * the block we haven't written data to.
468 */
469 bio_put(bio);
470 goto zero_tail;
471 }
472
473 n = bio->bi_iter.bi_size;
474 if (WARN_ON_ONCE((bio_opf & REQ_ATOMIC) && n != length)) {
475 /*
476 * An atomic write bio must cover the complete length,
477 * which it doesn't, so error. We may need to zero out
478 * the tail (complete FS block), similar to when
479 * bio_iov_iter_get_pages() returns an error, above.
480 */
481 ret = -EINVAL;
482 bio_put(bio);
483 goto zero_tail;
484 }
485 if (dio->flags & IOMAP_DIO_WRITE)
486 task_io_account_write(n);
487 else if (dio->flags & IOMAP_DIO_DIRTY)
488 bio_set_pages_dirty(bio);
489
490 dio->size += n;
491 copied += n;
492
493 nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter,
494 BIO_MAX_VECS);
495 /*
496 * We can only poll for single bio I/Os.
497 */
498 if (nr_pages)
499 dio->iocb->ki_flags &= ~IOCB_HIPRI;
500 iomap_dio_submit_bio(iter, dio, bio, pos);
501 pos += n;
502 } while (nr_pages);
503
504 /*
505 * We need to zeroout the tail of a sub-block write if the extent type
506 * requires zeroing or the write extends beyond EOF. If we don't zero
507 * the block tail in the latter case, we can expose stale data via mmap
508 * reads of the EOF block.
509 */
510 zero_tail:
511 if (need_zeroout ||
512 ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
513 /* zero out from the end of the write to the end of the block */
514 pad = pos & (fs_block_size - 1);
515 if (pad)
516 ret = iomap_dio_zero(iter, dio, pos,
517 fs_block_size - pad);
518 }
519 out:
520 /* Undo iter limitation to current extent */
521 iov_iter_reexpand(dio->submit.iter, orig_count - copied);
522 if (copied)
523 return iomap_iter_advance(iter, copied);
524 return ret;
525 }
526
iomap_dio_hole_iter(struct iomap_iter * iter,struct iomap_dio * dio)527 static int iomap_dio_hole_iter(struct iomap_iter *iter, struct iomap_dio *dio)
528 {
529 loff_t length = iov_iter_zero(iomap_length(iter), dio->submit.iter);
530
531 dio->size += length;
532 if (!length)
533 return -EFAULT;
534 return iomap_iter_advance(iter, length);
535 }
536
iomap_dio_inline_iter(struct iomap_iter * iomi,struct iomap_dio * dio)537 static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio)
538 {
539 const struct iomap *iomap = &iomi->iomap;
540 struct iov_iter *iter = dio->submit.iter;
541 void *inline_data = iomap_inline_data(iomap, iomi->pos);
542 loff_t length = iomap_length(iomi);
543 loff_t pos = iomi->pos;
544 u64 copied;
545
546 if (WARN_ON_ONCE(!inline_data))
547 return -EIO;
548
549 if (WARN_ON_ONCE(!iomap_inline_data_valid(iomap)))
550 return -EIO;
551
552 if (dio->flags & IOMAP_DIO_WRITE) {
553 loff_t size = iomi->inode->i_size;
554
555 if (pos > size)
556 memset(iomap_inline_data(iomap, size), 0, pos - size);
557 copied = copy_from_iter(inline_data, length, iter);
558 if (copied) {
559 if (pos + copied > size)
560 i_size_write(iomi->inode, pos + copied);
561 mark_inode_dirty(iomi->inode);
562 }
563 } else {
564 copied = copy_to_iter(inline_data, length, iter);
565 }
566 dio->size += copied;
567 if (!copied)
568 return -EFAULT;
569 return iomap_iter_advance(iomi, copied);
570 }
571
iomap_dio_iter(struct iomap_iter * iter,struct iomap_dio * dio)572 static int iomap_dio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
573 {
574 switch (iter->iomap.type) {
575 case IOMAP_HOLE:
576 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
577 return -EIO;
578 return iomap_dio_hole_iter(iter, dio);
579 case IOMAP_UNWRITTEN:
580 if (!(dio->flags & IOMAP_DIO_WRITE))
581 return iomap_dio_hole_iter(iter, dio);
582 return iomap_dio_bio_iter(iter, dio);
583 case IOMAP_MAPPED:
584 return iomap_dio_bio_iter(iter, dio);
585 case IOMAP_INLINE:
586 return iomap_dio_inline_iter(iter, dio);
587 case IOMAP_DELALLOC:
588 /*
589 * DIO is not serialised against mmap() access at all, and so
590 * if the page_mkwrite occurs between the writeback and the
591 * iomap_iter() call in the DIO path, then it will see the
592 * DELALLOC block that the page-mkwrite allocated.
593 */
594 pr_warn_ratelimited("Direct I/O collision with buffered writes! File: %pD4 Comm: %.20s\n",
595 dio->iocb->ki_filp, current->comm);
596 return -EIO;
597 default:
598 WARN_ON_ONCE(1);
599 return -EIO;
600 }
601 }
602
603 /*
604 * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
605 * is being issued as AIO or not. This allows us to optimise pure data writes
606 * to use REQ_FUA rather than requiring generic_write_sync() to issue a
607 * REQ_FLUSH post write. This is slightly tricky because a single request here
608 * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
609 * may be pure data writes. In that case, we still need to do a full data sync
610 * completion.
611 *
612 * When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL,
613 * __iomap_dio_rw can return a partial result if it encounters a non-resident
614 * page in @iter after preparing a transfer. In that case, the non-resident
615 * pages can be faulted in and the request resumed with @done_before set to the
616 * number of bytes previously transferred. The request will then complete with
617 * the correct total number of bytes transferred; this is essential for
618 * completing partial requests asynchronously.
619 *
620 * Returns -ENOTBLK In case of a page invalidation invalidation failure for
621 * writes. The callers needs to fall back to buffered I/O in this case.
622 */
623 struct iomap_dio *
__iomap_dio_rw(struct kiocb * iocb,struct iov_iter * iter,const struct iomap_ops * ops,const struct iomap_dio_ops * dops,unsigned int dio_flags,void * private,size_t done_before)624 __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
625 const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
626 unsigned int dio_flags, void *private, size_t done_before)
627 {
628 struct inode *inode = file_inode(iocb->ki_filp);
629 struct iomap_iter iomi = {
630 .inode = inode,
631 .pos = iocb->ki_pos,
632 .len = iov_iter_count(iter),
633 .flags = IOMAP_DIRECT,
634 .private = private,
635 };
636 bool wait_for_completion =
637 is_sync_kiocb(iocb) || (dio_flags & IOMAP_DIO_FORCE_WAIT);
638 struct blk_plug plug;
639 struct iomap_dio *dio;
640 loff_t ret = 0;
641
642 trace_iomap_dio_rw_begin(iocb, iter, dio_flags, done_before);
643
644 if (!iomi.len)
645 return NULL;
646
647 dio = kmalloc(sizeof(*dio), GFP_KERNEL);
648 if (!dio)
649 return ERR_PTR(-ENOMEM);
650
651 dio->iocb = iocb;
652 atomic_set(&dio->ref, 1);
653 dio->size = 0;
654 dio->i_size = i_size_read(inode);
655 dio->dops = dops;
656 dio->error = 0;
657 dio->flags = 0;
658 dio->done_before = done_before;
659
660 dio->submit.iter = iter;
661 dio->submit.waiter = current;
662
663 if (iocb->ki_flags & IOCB_NOWAIT)
664 iomi.flags |= IOMAP_NOWAIT;
665
666 if (dio_flags & IOMAP_DIO_FSBLOCK_ALIGNED)
667 dio->flags |= IOMAP_DIO_FSBLOCK_ALIGNED;
668
669 if (iov_iter_rw(iter) == READ) {
670 if (iomi.pos >= dio->i_size)
671 goto out_free_dio;
672
673 if (user_backed_iter(iter))
674 dio->flags |= IOMAP_DIO_DIRTY;
675
676 ret = kiocb_write_and_wait(iocb, iomi.len);
677 if (ret)
678 goto out_free_dio;
679 } else {
680 iomi.flags |= IOMAP_WRITE;
681 dio->flags |= IOMAP_DIO_WRITE;
682
683 if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) {
684 ret = -EAGAIN;
685 if (iomi.pos >= dio->i_size ||
686 iomi.pos + iomi.len > dio->i_size)
687 goto out_free_dio;
688 iomi.flags |= IOMAP_OVERWRITE_ONLY;
689 }
690
691 if (iocb->ki_flags & IOCB_ATOMIC)
692 iomi.flags |= IOMAP_ATOMIC;
693
694 /* for data sync or sync, we need sync completion processing */
695 if (iocb_is_dsync(iocb)) {
696 dio->flags |= IOMAP_DIO_NEED_SYNC;
697
698 /*
699 * For datasync only writes, we optimistically try using
700 * WRITE_THROUGH for this IO. This flag requires either
701 * FUA writes through the device's write cache, or a
702 * normal write to a device without a volatile write
703 * cache. For the former, Any non-FUA write that occurs
704 * will clear this flag, hence we know before completion
705 * whether a cache flush is necessary.
706 */
707 if (!(iocb->ki_flags & IOCB_SYNC))
708 dio->flags |= IOMAP_DIO_WRITE_THROUGH;
709 }
710
711 /*
712 * i_size updates must to happen from process context.
713 */
714 if (iomi.pos + iomi.len > dio->i_size)
715 dio->flags |= IOMAP_DIO_COMP_WORK;
716
717 /*
718 * Try to invalidate cache pages for the range we are writing.
719 * If this invalidation fails, let the caller fall back to
720 * buffered I/O.
721 */
722 ret = kiocb_invalidate_pages(iocb, iomi.len);
723 if (ret) {
724 if (ret != -EAGAIN) {
725 trace_iomap_dio_invalidate_fail(inode, iomi.pos,
726 iomi.len);
727 if (iocb->ki_flags & IOCB_ATOMIC) {
728 /*
729 * folio invalidation failed, maybe
730 * this is transient, unlock and see if
731 * the caller tries again.
732 */
733 ret = -EAGAIN;
734 } else {
735 /* fall back to buffered write */
736 ret = -ENOTBLK;
737 }
738 }
739 goto out_free_dio;
740 }
741 }
742
743 if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) {
744 ret = sb_init_dio_done_wq(inode->i_sb);
745 if (ret < 0)
746 goto out_free_dio;
747 }
748
749 inode_dio_begin(inode);
750
751 blk_start_plug(&plug);
752 while ((ret = iomap_iter(&iomi, ops)) > 0) {
753 iomi.status = iomap_dio_iter(&iomi, dio);
754
755 /*
756 * We can only poll for single bio I/Os.
757 */
758 iocb->ki_flags &= ~IOCB_HIPRI;
759 }
760
761 blk_finish_plug(&plug);
762
763 /*
764 * We only report that we've read data up to i_size.
765 * Revert iter to a state corresponding to that as some callers (such
766 * as the splice code) rely on it.
767 */
768 if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size)
769 iov_iter_revert(iter, iomi.pos - dio->i_size);
770
771 if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) {
772 if (!(iocb->ki_flags & IOCB_NOWAIT))
773 wait_for_completion = true;
774 ret = 0;
775 }
776
777 /* magic error code to fall back to buffered I/O */
778 if (ret == -ENOTBLK) {
779 wait_for_completion = true;
780 ret = 0;
781 }
782 if (ret < 0)
783 iomap_dio_set_error(dio, ret);
784
785 /*
786 * If all the writes we issued were already written through to the
787 * media, we don't need to flush the cache on IO completion. Clear the
788 * sync flag for this case.
789 *
790 * Otherwise clear the inline completion flag if any sync work is
791 * needed, as that needs to be performed from process context.
792 */
793 if (dio->flags & IOMAP_DIO_WRITE_THROUGH)
794 dio->flags &= ~IOMAP_DIO_NEED_SYNC;
795 else if (dio->flags & IOMAP_DIO_NEED_SYNC)
796 dio->flags |= IOMAP_DIO_COMP_WORK;
797
798 /*
799 * We are about to drop our additional submission reference, which
800 * might be the last reference to the dio. There are three different
801 * ways we can progress here:
802 *
803 * (a) If this is the last reference we will always complete and free
804 * the dio ourselves.
805 * (b) If this is not the last reference, and we serve an asynchronous
806 * iocb, we must never touch the dio after the decrement, the
807 * I/O completion handler will complete and free it.
808 * (c) If this is not the last reference, but we serve a synchronous
809 * iocb, the I/O completion handler will wake us up on the drop
810 * of the final reference, and we will complete and free it here
811 * after we got woken by the I/O completion handler.
812 */
813 dio->wait_for_completion = wait_for_completion;
814 if (!atomic_dec_and_test(&dio->ref)) {
815 if (!wait_for_completion) {
816 trace_iomap_dio_rw_queued(inode, iomi.pos, iomi.len);
817 return ERR_PTR(-EIOCBQUEUED);
818 }
819
820 for (;;) {
821 set_current_state(TASK_UNINTERRUPTIBLE);
822 if (!READ_ONCE(dio->submit.waiter))
823 break;
824
825 blk_io_schedule();
826 }
827 __set_current_state(TASK_RUNNING);
828 }
829
830 return dio;
831
832 out_free_dio:
833 kfree(dio);
834 if (ret)
835 return ERR_PTR(ret);
836 return NULL;
837 }
838 EXPORT_SYMBOL_GPL(__iomap_dio_rw);
839
840 ssize_t
iomap_dio_rw(struct kiocb * iocb,struct iov_iter * iter,const struct iomap_ops * ops,const struct iomap_dio_ops * dops,unsigned int dio_flags,void * private,size_t done_before)841 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
842 const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
843 unsigned int dio_flags, void *private, size_t done_before)
844 {
845 struct iomap_dio *dio;
846
847 dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, private,
848 done_before);
849 if (IS_ERR_OR_NULL(dio))
850 return PTR_ERR_OR_ZERO(dio);
851 return iomap_dio_complete(dio);
852 }
853 EXPORT_SYMBOL_GPL(iomap_dio_rw);
854