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1/*
2 * Copyright (C) 2010 Red Hat, Inc.
3 * Copyright (c) 2016 Christoph Hellwig.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 */
14#include <linux/module.h>
15#include <linux/compiler.h>
16#include <linux/fs.h>
17#include <linux/iomap.h>
18#include <linux/uaccess.h>
19#include <linux/gfp.h>
20#include <linux/mm.h>
21#include <linux/swap.h>
22#include <linux/pagemap.h>
23#include <linux/file.h>
24#include <linux/uio.h>
25#include <linux/backing-dev.h>
26#include <linux/buffer_head.h>
27#include <linux/task_io_accounting_ops.h>
28#include <linux/dax.h>
29#include <linux/sched/signal.h>
30
31#include "internal.h"
32
33/*
34 * Execute a iomap write on a segment of the mapping that spans a
35 * contiguous range of pages that have identical block mapping state.
36 *
37 * This avoids the need to map pages individually, do individual allocations
38 * for each page and most importantly avoid the need for filesystem specific
39 * locking per page. Instead, all the operations are amortised over the entire
40 * range of pages. It is assumed that the filesystems will lock whatever
41 * resources they require in the iomap_begin call, and release them in the
42 * iomap_end call.
43 */
44loff_t
45iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
46 const struct iomap_ops *ops, void *data, iomap_actor_t actor)
47{
48 struct iomap iomap = { 0 };
49 loff_t written = 0, ret;
50
51 /*
52 * Need to map a range from start position for length bytes. This can
53 * span multiple pages - it is only guaranteed to return a range of a
54 * single type of pages (e.g. all into a hole, all mapped or all
55 * unwritten). Failure at this point has nothing to undo.
56 *
57 * If allocation is required for this range, reserve the space now so
58 * that the allocation is guaranteed to succeed later on. Once we copy
59 * the data into the page cache pages, then we cannot fail otherwise we
60 * expose transient stale data. If the reserve fails, we can safely
61 * back out at this point as there is nothing to undo.
62 */
63 ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
64 if (ret)
65 return ret;
66 if (WARN_ON(iomap.offset > pos))
67 return -EIO;
68
69 /*
70 * Cut down the length to the one actually provided by the filesystem,
71 * as it might not be able to give us the whole size that we requested.
72 */
73 if (iomap.offset + iomap.length < pos + length)
74 length = iomap.offset + iomap.length - pos;
75
76 /*
77 * Now that we have guaranteed that the space allocation will succeed.
78 * we can do the copy-in page by page without having to worry about
79 * failures exposing transient data.
80 */
81 written = actor(inode, pos, length, data, &iomap);
82
83 /*
84 * Now the data has been copied, commit the range we've copied. This
85 * should not fail unless the filesystem has had a fatal error.
86 */
87 if (ops->iomap_end) {
88 ret = ops->iomap_end(inode, pos, length,
89 written > 0 ? written : 0,
90 flags, &iomap);
91 }
92
93 return written ? written : ret;
94}
95
96static void
97iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
98{
99 loff_t i_size = i_size_read(inode);
100
101 /*
102 * Only truncate newly allocated pages beyoned EOF, even if the
103 * write started inside the existing inode size.
104 */
105 if (pos + len > i_size)
106 truncate_pagecache_range(inode, max(pos, i_size), pos + len);
107}
108
109static int
110iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
111 struct page **pagep, struct iomap *iomap)
112{
113 pgoff_t index = pos >> PAGE_SHIFT;
114 struct page *page;
115 int status = 0;
116
117 BUG_ON(pos + len > iomap->offset + iomap->length);
118
119 if (fatal_signal_pending(current))
120 return -EINTR;
121
122 page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
123 if (!page)
124 return -ENOMEM;
125
126 status = __block_write_begin_int(page, pos, len, NULL, iomap);
127 if (unlikely(status)) {
128 unlock_page(page);
129 put_page(page);
130 page = NULL;
131
132 iomap_write_failed(inode, pos, len);
133 }
134
135 *pagep = page;
136 return status;
137}
138
139static int
140iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
141 unsigned copied, struct page *page)
142{
143 int ret;
144
145 ret = generic_write_end(NULL, inode->i_mapping, pos, len,
146 copied, page, NULL);
147 if (ret < len)
148 iomap_write_failed(inode, pos, len);
149 return ret;
150}
151
152static loff_t
153iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
154 struct iomap *iomap)
155{
156 struct iov_iter *i = data;
157 long status = 0;
158 ssize_t written = 0;
159 unsigned int flags = AOP_FLAG_NOFS;
160
161 do {
162 struct page *page;
163 unsigned long offset; /* Offset into pagecache page */
164 unsigned long bytes; /* Bytes to write to page */
165 size_t copied; /* Bytes copied from user */
166
167 offset = (pos & (PAGE_SIZE - 1));
168 bytes = min_t(unsigned long, PAGE_SIZE - offset,
169 iov_iter_count(i));
170again:
171 if (bytes > length)
172 bytes = length;
173
174 /*
175 * Bring in the user page that we will copy from _first_.
176 * Otherwise there's a nasty deadlock on copying from the
177 * same page as we're writing to, without it being marked
178 * up-to-date.
179 *
180 * Not only is this an optimisation, but it is also required
181 * to check that the address is actually valid, when atomic
182 * usercopies are used, below.
183 */
184 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
185 status = -EFAULT;
186 break;
187 }
188
189 status = iomap_write_begin(inode, pos, bytes, flags, &page,
190 iomap);
191 if (unlikely(status))
192 break;
193
194 if (mapping_writably_mapped(inode->i_mapping))
195 flush_dcache_page(page);
196
197 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
198
199 flush_dcache_page(page);
200
201 status = iomap_write_end(inode, pos, bytes, copied, page);
202 if (unlikely(status < 0))
203 break;
204 copied = status;
205
206 cond_resched();
207
208 iov_iter_advance(i, copied);
209 if (unlikely(copied == 0)) {
210 /*
211 * If we were unable to copy any data at all, we must
212 * fall back to a single segment length write.
213 *
214 * If we didn't fallback here, we could livelock
215 * because not all segments in the iov can be copied at
216 * once without a pagefault.
217 */
218 bytes = min_t(unsigned long, PAGE_SIZE - offset,
219 iov_iter_single_seg_count(i));
220 goto again;
221 }
222 pos += copied;
223 written += copied;
224 length -= copied;
225
226 balance_dirty_pages_ratelimited(inode->i_mapping);
227 } while (iov_iter_count(i) && length);
228
229 return written ? written : status;
230}
231
232ssize_t
233iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
234 const struct iomap_ops *ops)
235{
236 struct inode *inode = iocb->ki_filp->f_mapping->host;
237 loff_t pos = iocb->ki_pos, ret = 0, written = 0;
238
239 while (iov_iter_count(iter)) {
240 ret = iomap_apply(inode, pos, iov_iter_count(iter),
241 IOMAP_WRITE, ops, iter, iomap_write_actor);
242 if (ret <= 0)
243 break;
244 pos += ret;
245 written += ret;
246 }
247
248 return written ? written : ret;
249}
250EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
251
252static struct page *
253__iomap_read_page(struct inode *inode, loff_t offset)
254{
255 struct address_space *mapping = inode->i_mapping;
256 struct page *page;
257
258 page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
259 if (IS_ERR(page))
260 return page;
261 if (!PageUptodate(page)) {
262 put_page(page);
263 return ERR_PTR(-EIO);
264 }
265 return page;
266}
267
268static loff_t
269iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
270 struct iomap *iomap)
271{
272 long status = 0;
273 ssize_t written = 0;
274
275 do {
276 struct page *page, *rpage;
277 unsigned long offset; /* Offset into pagecache page */
278 unsigned long bytes; /* Bytes to write to page */
279
280 offset = (pos & (PAGE_SIZE - 1));
281 bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
282
283 rpage = __iomap_read_page(inode, pos);
284 if (IS_ERR(rpage))
285 return PTR_ERR(rpage);
286
287 status = iomap_write_begin(inode, pos, bytes,
288 AOP_FLAG_NOFS, &page, iomap);
289 put_page(rpage);
290 if (unlikely(status))
291 return status;
292
293 WARN_ON_ONCE(!PageUptodate(page));
294
295 status = iomap_write_end(inode, pos, bytes, bytes, page);
296 if (unlikely(status <= 0)) {
297 if (WARN_ON_ONCE(status == 0))
298 return -EIO;
299 return status;
300 }
301
302 cond_resched();
303
304 pos += status;
305 written += status;
306 length -= status;
307
308 balance_dirty_pages_ratelimited(inode->i_mapping);
309 } while (length);
310
311 return written;
312}
313
314int
315iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
316 const struct iomap_ops *ops)
317{
318 loff_t ret;
319
320 while (len) {
321 ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
322 iomap_dirty_actor);
323 if (ret <= 0)
324 return ret;
325 pos += ret;
326 len -= ret;
327 }
328
329 return 0;
330}
331EXPORT_SYMBOL_GPL(iomap_file_dirty);
332
333static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
334 unsigned bytes, struct iomap *iomap)
335{
336 struct page *page;
337 int status;
338
339 status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page,
340 iomap);
341 if (status)
342 return status;
343
344 zero_user(page, offset, bytes);
345 mark_page_accessed(page);
346
347 return iomap_write_end(inode, pos, bytes, bytes, page);
348}
349
350static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
351 struct iomap *iomap)
352{
353 sector_t sector = iomap->blkno +
354 (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);
355
356 return __dax_zero_page_range(iomap->bdev, iomap->dax_dev, sector,
357 offset, bytes);
358}
359
360static loff_t
361iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
362 void *data, struct iomap *iomap)
363{
364 bool *did_zero = data;
365 loff_t written = 0;
366 int status;
367
368 /* already zeroed? we're done. */
369 if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
370 return count;
371
372 do {
373 unsigned offset, bytes;
374
375 offset = pos & (PAGE_SIZE - 1); /* Within page */
376 bytes = min_t(unsigned, PAGE_SIZE - offset, count);
377
378 if (IS_DAX(inode))
379 status = iomap_dax_zero(pos, offset, bytes, iomap);
380 else
381 status = iomap_zero(inode, pos, offset, bytes, iomap);
382 if (status < 0)
383 return status;
384
385 pos += bytes;
386 count -= bytes;
387 written += bytes;
388 if (did_zero)
389 *did_zero = true;
390 } while (count > 0);
391
392 return written;
393}
394
395int
396iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
397 const struct iomap_ops *ops)
398{
399 loff_t ret;
400
401 while (len > 0) {
402 ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
403 ops, did_zero, iomap_zero_range_actor);
404 if (ret <= 0)
405 return ret;
406
407 pos += ret;
408 len -= ret;
409 }
410
411 return 0;
412}
413EXPORT_SYMBOL_GPL(iomap_zero_range);
414
415int
416iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
417 const struct iomap_ops *ops)
418{
419 unsigned int blocksize = i_blocksize(inode);
420 unsigned int off = pos & (blocksize - 1);
421
422 /* Block boundary? Nothing to do */
423 if (!off)
424 return 0;
425 return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
426}
427EXPORT_SYMBOL_GPL(iomap_truncate_page);
428
429static loff_t
430iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
431 void *data, struct iomap *iomap)
432{
433 struct page *page = data;
434 int ret;
435
436 ret = __block_write_begin_int(page, pos, length, NULL, iomap);
437 if (ret)
438 return ret;
439
440 block_commit_write(page, 0, length);
441 return length;
442}
443
444int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
445{
446 struct page *page = vmf->page;
447 struct inode *inode = file_inode(vmf->vma->vm_file);
448 unsigned long length;
449 loff_t offset, size;
450 ssize_t ret;
451
452 lock_page(page);
453 size = i_size_read(inode);
454 if ((page->mapping != inode->i_mapping) ||
455 (page_offset(page) > size)) {
456 /* We overload EFAULT to mean page got truncated */
457 ret = -EFAULT;
458 goto out_unlock;
459 }
460
461 /* page is wholly or partially inside EOF */
462 if (((page->index + 1) << PAGE_SHIFT) > size)
463 length = size & ~PAGE_MASK;
464 else
465 length = PAGE_SIZE;
466
467 offset = page_offset(page);
468 while (length > 0) {
469 ret = iomap_apply(inode, offset, length,
470 IOMAP_WRITE | IOMAP_FAULT, ops, page,
471 iomap_page_mkwrite_actor);
472 if (unlikely(ret <= 0))
473 goto out_unlock;
474 offset += ret;
475 length -= ret;
476 }
477
478 set_page_dirty(page);
479 wait_for_stable_page(page);
480 return 0;
481out_unlock:
482 unlock_page(page);
483 return ret;
484}
485EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
486
487struct fiemap_ctx {
488 struct fiemap_extent_info *fi;
489 struct iomap prev;
490};
491
492static int iomap_to_fiemap(struct fiemap_extent_info *fi,
493 struct iomap *iomap, u32 flags)
494{
495 switch (iomap->type) {
496 case IOMAP_HOLE:
497 /* skip holes */
498 return 0;
499 case IOMAP_DELALLOC:
500 flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
501 break;
502 case IOMAP_UNWRITTEN:
503 flags |= FIEMAP_EXTENT_UNWRITTEN;
504 break;
505 case IOMAP_MAPPED:
506 break;
507 }
508
509 if (iomap->flags & IOMAP_F_MERGED)
510 flags |= FIEMAP_EXTENT_MERGED;
511 if (iomap->flags & IOMAP_F_SHARED)
512 flags |= FIEMAP_EXTENT_SHARED;
513
514 return fiemap_fill_next_extent(fi, iomap->offset,
515 iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
516 iomap->length, flags);
517
518}
519
520static loff_t
521iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
522 struct iomap *iomap)
523{
524 struct fiemap_ctx *ctx = data;
525 loff_t ret = length;
526
527 if (iomap->type == IOMAP_HOLE)
528 return length;
529
530 ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
531 ctx->prev = *iomap;
532 switch (ret) {
533 case 0: /* success */
534 return length;
535 case 1: /* extent array full */
536 return 0;
537 default:
538 return ret;
539 }
540}
541
542int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
543 loff_t start, loff_t len, const struct iomap_ops *ops)
544{
545 struct fiemap_ctx ctx;
546 loff_t ret;
547
548 memset(&ctx, 0, sizeof(ctx));
549 ctx.fi = fi;
550 ctx.prev.type = IOMAP_HOLE;
551
552 ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
553 if (ret)
554 return ret;
555
556 if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
557 ret = filemap_write_and_wait(inode->i_mapping);
558 if (ret)
559 return ret;
560 }
561
562 while (len > 0) {
563 ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
564 iomap_fiemap_actor);
565 /* inode with no (attribute) mapping will give ENOENT */
566 if (ret == -ENOENT)
567 break;
568 if (ret < 0)
569 return ret;
570 if (ret == 0)
571 break;
572
573 start += ret;
574 len -= ret;
575 }
576
577 if (ctx.prev.type != IOMAP_HOLE) {
578 ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
579 if (ret < 0)
580 return ret;
581 }
582
583 return 0;
584}
585EXPORT_SYMBOL_GPL(iomap_fiemap);
586
587static loff_t
588iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
589 void *data, struct iomap *iomap)
590{
591 switch (iomap->type) {
592 case IOMAP_UNWRITTEN:
593 offset = page_cache_seek_hole_data(inode, offset, length,
594 SEEK_HOLE);
595 if (offset < 0)
596 return length;
597 /* fall through */
598 case IOMAP_HOLE:
599 *(loff_t *)data = offset;
600 return 0;
601 default:
602 return length;
603 }
604}
605
606loff_t
607iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
608{
609 loff_t size = i_size_read(inode);
610 loff_t length = size - offset;
611 loff_t ret;
612
613 /* Nothing to be found beyond the end of the file. */
614 if (offset >= size)
615 return -ENXIO;
616
617 while (length > 0) {
618 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
619 &offset, iomap_seek_hole_actor);
620 if (ret < 0)
621 return ret;
622 if (ret == 0)
623 break;
624
625 offset += ret;
626 length -= ret;
627 }
628
629 return offset;
630}
631EXPORT_SYMBOL_GPL(iomap_seek_hole);
632
633static loff_t
634iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
635 void *data, struct iomap *iomap)
636{
637 switch (iomap->type) {
638 case IOMAP_HOLE:
639 return length;
640 case IOMAP_UNWRITTEN:
641 offset = page_cache_seek_hole_data(inode, offset, length,
642 SEEK_DATA);
643 if (offset < 0)
644 return length;
645 /*FALLTHRU*/
646 default:
647 *(loff_t *)data = offset;
648 return 0;
649 }
650}
651
652loff_t
653iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
654{
655 loff_t size = i_size_read(inode);
656 loff_t length = size - offset;
657 loff_t ret;
658
659 /* Nothing to be found beyond the end of the file. */
660 if (offset >= size)
661 return -ENXIO;
662
663 while (length > 0) {
664 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
665 &offset, iomap_seek_data_actor);
666 if (ret < 0)
667 return ret;
668 if (ret == 0)
669 break;
670
671 offset += ret;
672 length -= ret;
673 }
674
675 if (length <= 0)
676 return -ENXIO;
677 return offset;
678}
679EXPORT_SYMBOL_GPL(iomap_seek_data);
680
681/*
682 * Private flags for iomap_dio, must not overlap with the public ones in
683 * iomap.h:
684 */
685#define IOMAP_DIO_WRITE (1 << 30)
686#define IOMAP_DIO_DIRTY (1 << 31)
687
688struct iomap_dio {
689 struct kiocb *iocb;
690 iomap_dio_end_io_t *end_io;
691 loff_t i_size;
692 loff_t size;
693 atomic_t ref;
694 unsigned flags;
695 int error;
696
697 union {
698 /* used during submission and for synchronous completion: */
699 struct {
700 struct iov_iter *iter;
701 struct task_struct *waiter;
702 struct request_queue *last_queue;
703 blk_qc_t cookie;
704 } submit;
705
706 /* used for aio completion: */
707 struct {
708 struct work_struct work;
709 } aio;
710 };
711};
712
713static ssize_t iomap_dio_complete(struct iomap_dio *dio)
714{
715 struct kiocb *iocb = dio->iocb;
716 ssize_t ret;
717
718 if (dio->end_io) {
719 ret = dio->end_io(iocb,
720 dio->error ? dio->error : dio->size,
721 dio->flags);
722 } else {
723 ret = dio->error;
724 }
725
726 if (likely(!ret)) {
727 ret = dio->size;
728 /* check for short read */
729 if (iocb->ki_pos + ret > dio->i_size &&
730 !(dio->flags & IOMAP_DIO_WRITE))
731 ret = dio->i_size - iocb->ki_pos;
732 iocb->ki_pos += ret;
733 }
734
735 inode_dio_end(file_inode(iocb->ki_filp));
736 kfree(dio);
737
738 return ret;
739}
740
741static void iomap_dio_complete_work(struct work_struct *work)
742{
743 struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
744 struct kiocb *iocb = dio->iocb;
745 bool is_write = (dio->flags & IOMAP_DIO_WRITE);
746 ssize_t ret;
747
748 ret = iomap_dio_complete(dio);
749 if (is_write && ret > 0)
750 ret = generic_write_sync(iocb, ret);
751 iocb->ki_complete(iocb, ret, 0);
752}
753
754/*
755 * Set an error in the dio if none is set yet. We have to use cmpxchg
756 * as the submission context and the completion context(s) can race to
757 * update the error.
758 */
759static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
760{
761 cmpxchg(&dio->error, 0, ret);
762}
763
764static void iomap_dio_bio_end_io(struct bio *bio)
765{
766 struct iomap_dio *dio = bio->bi_private;
767 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
768
769 if (bio->bi_status)
770 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
771
772 if (atomic_dec_and_test(&dio->ref)) {
773 if (is_sync_kiocb(dio->iocb)) {
774 struct task_struct *waiter = dio->submit.waiter;
775
776 WRITE_ONCE(dio->submit.waiter, NULL);
777 wake_up_process(waiter);
778 } else if (dio->flags & IOMAP_DIO_WRITE) {
779 struct inode *inode = file_inode(dio->iocb->ki_filp);
780
781 INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
782 queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
783 } else {
784 iomap_dio_complete_work(&dio->aio.work);
785 }
786 }
787
788 if (should_dirty) {
789 bio_check_pages_dirty(bio);
790 } else {
791 struct bio_vec *bvec;
792 int i;
793
794 bio_for_each_segment_all(bvec, bio, i)
795 put_page(bvec->bv_page);
796 bio_put(bio);
797 }
798}
799
800static blk_qc_t
801iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
802 unsigned len)
803{
804 struct page *page = ZERO_PAGE(0);
805 struct bio *bio;
806
807 bio = bio_alloc(GFP_KERNEL, 1);
808 bio->bi_bdev = iomap->bdev;
809 bio->bi_iter.bi_sector =
810 iomap->blkno + ((pos - iomap->offset) >> 9);
811 bio->bi_private = dio;
812 bio->bi_end_io = iomap_dio_bio_end_io;
813
814 get_page(page);
815 if (bio_add_page(bio, page, len, 0) != len)
816 BUG();
817 bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
818
819 atomic_inc(&dio->ref);
820 return submit_bio(bio);
821}
822
823static loff_t
824iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
825 void *data, struct iomap *iomap)
826{
827 struct iomap_dio *dio = data;
828 unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
829 unsigned int fs_block_size = i_blocksize(inode), pad;
830 unsigned int align = iov_iter_alignment(dio->submit.iter);
831 struct iov_iter iter;
832 struct bio *bio;
833 bool need_zeroout = false;
834 int nr_pages, ret;
835
836 if ((pos | length | align) & ((1 << blkbits) - 1))
837 return -EINVAL;
838
839 switch (iomap->type) {
840 case IOMAP_HOLE:
841 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
842 return -EIO;
843 /*FALLTHRU*/
844 case IOMAP_UNWRITTEN:
845 if (!(dio->flags & IOMAP_DIO_WRITE)) {
846 iov_iter_zero(length, dio->submit.iter);
847 dio->size += length;
848 return length;
849 }
850 dio->flags |= IOMAP_DIO_UNWRITTEN;
851 need_zeroout = true;
852 break;
853 case IOMAP_MAPPED:
854 if (iomap->flags & IOMAP_F_SHARED)
855 dio->flags |= IOMAP_DIO_COW;
856 if (iomap->flags & IOMAP_F_NEW)
857 need_zeroout = true;
858 break;
859 default:
860 WARN_ON_ONCE(1);
861 return -EIO;
862 }
863
864 /*
865 * Operate on a partial iter trimmed to the extent we were called for.
866 * We'll update the iter in the dio once we're done with this extent.
867 */
868 iter = *dio->submit.iter;
869 iov_iter_truncate(&iter, length);
870
871 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
872 if (nr_pages <= 0)
873 return nr_pages;
874
875 if (need_zeroout) {
876 /* zero out from the start of the block to the write offset */
877 pad = pos & (fs_block_size - 1);
878 if (pad)
879 iomap_dio_zero(dio, iomap, pos - pad, pad);
880 }
881
882 do {
883 if (dio->error)
884 return 0;
885
886 bio = bio_alloc(GFP_KERNEL, nr_pages);
887 bio->bi_bdev = iomap->bdev;
888 bio->bi_iter.bi_sector =
889 iomap->blkno + ((pos - iomap->offset) >> 9);
890 bio->bi_write_hint = dio->iocb->ki_hint;
891 bio->bi_private = dio;
892 bio->bi_end_io = iomap_dio_bio_end_io;
893
894 ret = bio_iov_iter_get_pages(bio, &iter);
895 if (unlikely(ret)) {
896 bio_put(bio);
897 return ret;
898 }
899
900 if (dio->flags & IOMAP_DIO_WRITE) {
901 bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
902 task_io_account_write(bio->bi_iter.bi_size);
903 } else {
904 bio_set_op_attrs(bio, REQ_OP_READ, 0);
905 if (dio->flags & IOMAP_DIO_DIRTY)
906 bio_set_pages_dirty(bio);
907 }
908
909 dio->size += bio->bi_iter.bi_size;
910 pos += bio->bi_iter.bi_size;
911
912 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
913
914 atomic_inc(&dio->ref);
915
916 dio->submit.last_queue = bdev_get_queue(iomap->bdev);
917 dio->submit.cookie = submit_bio(bio);
918 } while (nr_pages);
919
920 if (need_zeroout) {
921 /* zero out from the end of the write to the end of the block */
922 pad = pos & (fs_block_size - 1);
923 if (pad)
924 iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
925 }
926
927 iov_iter_advance(dio->submit.iter, length);
928 return length;
929}
930
931ssize_t
932iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
933 const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
934{
935 struct address_space *mapping = iocb->ki_filp->f_mapping;
936 struct inode *inode = file_inode(iocb->ki_filp);
937 size_t count = iov_iter_count(iter);
938 loff_t pos = iocb->ki_pos, start = pos;
939 loff_t end = iocb->ki_pos + count - 1, ret = 0;
940 unsigned int flags = IOMAP_DIRECT;
941 struct blk_plug plug;
942 struct iomap_dio *dio;
943
944 lockdep_assert_held(&inode->i_rwsem);
945
946 if (!count)
947 return 0;
948
949 dio = kmalloc(sizeof(*dio), GFP_KERNEL);
950 if (!dio)
951 return -ENOMEM;
952
953 dio->iocb = iocb;
954 atomic_set(&dio->ref, 1);
955 dio->size = 0;
956 dio->i_size = i_size_read(inode);
957 dio->end_io = end_io;
958 dio->error = 0;
959 dio->flags = 0;
960
961 dio->submit.iter = iter;
962 if (is_sync_kiocb(iocb)) {
963 dio->submit.waiter = current;
964 dio->submit.cookie = BLK_QC_T_NONE;
965 dio->submit.last_queue = NULL;
966 }
967
968 if (iov_iter_rw(iter) == READ) {
969 if (pos >= dio->i_size)
970 goto out_free_dio;
971
972 if (iter->type == ITER_IOVEC)
973 dio->flags |= IOMAP_DIO_DIRTY;
974 } else {
975 dio->flags |= IOMAP_DIO_WRITE;
976 flags |= IOMAP_WRITE;
977 }
978
979 if (iocb->ki_flags & IOCB_NOWAIT) {
980 if (filemap_range_has_page(mapping, start, end)) {
981 ret = -EAGAIN;
982 goto out_free_dio;
983 }
984 flags |= IOMAP_NOWAIT;
985 }
986
987 ret = filemap_write_and_wait_range(mapping, start, end);
988 if (ret)
989 goto out_free_dio;
990
991 ret = invalidate_inode_pages2_range(mapping,
992 start >> PAGE_SHIFT, end >> PAGE_SHIFT);
993 WARN_ON_ONCE(ret);
994 ret = 0;
995
996 inode_dio_begin(inode);
997
998 blk_start_plug(&plug);
999 do {
1000 ret = iomap_apply(inode, pos, count, flags, ops, dio,
1001 iomap_dio_actor);
1002 if (ret <= 0) {
1003 /* magic error code to fall back to buffered I/O */
1004 if (ret == -ENOTBLK)
1005 ret = 0;
1006 break;
1007 }
1008 pos += ret;
1009
1010 if (iov_iter_rw(iter) == READ && pos >= dio->i_size)
1011 break;
1012 } while ((count = iov_iter_count(iter)) > 0);
1013 blk_finish_plug(&plug);
1014
1015 if (ret < 0)
1016 iomap_dio_set_error(dio, ret);
1017
1018 if (ret >= 0 && iov_iter_rw(iter) == WRITE && !is_sync_kiocb(iocb) &&
1019 !inode->i_sb->s_dio_done_wq) {
1020 ret = sb_init_dio_done_wq(inode->i_sb);
1021 if (ret < 0)
1022 iomap_dio_set_error(dio, ret);
1023 }
1024
1025 if (!atomic_dec_and_test(&dio->ref)) {
1026 if (!is_sync_kiocb(iocb))
1027 return -EIOCBQUEUED;
1028
1029 for (;;) {
1030 set_current_state(TASK_UNINTERRUPTIBLE);
1031 if (!READ_ONCE(dio->submit.waiter))
1032 break;
1033
1034 if (!(iocb->ki_flags & IOCB_HIPRI) ||
1035 !dio->submit.last_queue ||
1036 !blk_mq_poll(dio->submit.last_queue,
1037 dio->submit.cookie))
1038 io_schedule();
1039 }
1040 __set_current_state(TASK_RUNNING);
1041 }
1042
1043 ret = iomap_dio_complete(dio);
1044
1045 /*
1046 * Try again to invalidate clean pages which might have been cached by
1047 * non-direct readahead, or faulted in by get_user_pages() if the source
1048 * of the write was an mmap'ed region of the file we're writing. Either
1049 * one is a pretty crazy thing to do, so we don't support it 100%. If
1050 * this invalidation fails, tough, the write still worked...
1051 */
1052 if (iov_iter_rw(iter) == WRITE) {
1053 int err = invalidate_inode_pages2_range(mapping,
1054 start >> PAGE_SHIFT, end >> PAGE_SHIFT);
1055 WARN_ON_ONCE(err);
1056 }
1057
1058 return ret;
1059
1060out_free_dio:
1061 kfree(dio);
1062 return ret;
1063}
1064EXPORT_SYMBOL_GPL(iomap_dio_rw);