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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (c) 2016-2018 Christoph Hellwig.
5 */
6#include <linux/module.h>
7#include <linux/compiler.h>
8#include <linux/fs.h>
9#include <linux/iomap.h>
10#include <linux/pagemap.h>
11#include <linux/uio.h>
12#include <linux/buffer_head.h>
13#include <linux/dax.h>
14#include <linux/writeback.h>
15#include <linux/swap.h>
16#include <linux/bio.h>
17#include <linux/sched/signal.h>
18#include <linux/migrate.h>
19
20#include "../internal.h"
21
22static struct iomap_page *
23iomap_page_create(struct inode *inode, struct page *page)
24{
25 struct iomap_page *iop = to_iomap_page(page);
26
27 if (iop || i_blocksize(inode) == PAGE_SIZE)
28 return iop;
29
30 iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
31 atomic_set(&iop->read_count, 0);
32 atomic_set(&iop->write_count, 0);
33 bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
34
35 /*
36 * migrate_page_move_mapping() assumes that pages with private data have
37 * their count elevated by 1.
38 */
39 get_page(page);
40 set_page_private(page, (unsigned long)iop);
41 SetPagePrivate(page);
42 return iop;
43}
44
45static void
46iomap_page_release(struct page *page)
47{
48 struct iomap_page *iop = to_iomap_page(page);
49
50 if (!iop)
51 return;
52 WARN_ON_ONCE(atomic_read(&iop->read_count));
53 WARN_ON_ONCE(atomic_read(&iop->write_count));
54 ClearPagePrivate(page);
55 set_page_private(page, 0);
56 put_page(page);
57 kfree(iop);
58}
59
60/*
61 * Calculate the range inside the page that we actually need to read.
62 */
63static void
64iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
65 loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
66{
67 loff_t orig_pos = *pos;
68 loff_t isize = i_size_read(inode);
69 unsigned block_bits = inode->i_blkbits;
70 unsigned block_size = (1 << block_bits);
71 unsigned poff = offset_in_page(*pos);
72 unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
73 unsigned first = poff >> block_bits;
74 unsigned last = (poff + plen - 1) >> block_bits;
75
76 /*
77 * If the block size is smaller than the page size we need to check the
78 * per-block uptodate status and adjust the offset and length if needed
79 * to avoid reading in already uptodate ranges.
80 */
81 if (iop) {
82 unsigned int i;
83
84 /* move forward for each leading block marked uptodate */
85 for (i = first; i <= last; i++) {
86 if (!test_bit(i, iop->uptodate))
87 break;
88 *pos += block_size;
89 poff += block_size;
90 plen -= block_size;
91 first++;
92 }
93
94 /* truncate len if we find any trailing uptodate block(s) */
95 for ( ; i <= last; i++) {
96 if (test_bit(i, iop->uptodate)) {
97 plen -= (last - i + 1) * block_size;
98 last = i - 1;
99 break;
100 }
101 }
102 }
103
104 /*
105 * If the extent spans the block that contains the i_size we need to
106 * handle both halves separately so that we properly zero data in the
107 * page cache for blocks that are entirely outside of i_size.
108 */
109 if (orig_pos <= isize && orig_pos + length > isize) {
110 unsigned end = offset_in_page(isize - 1) >> block_bits;
111
112 if (first <= end && last > end)
113 plen -= (last - end) * block_size;
114 }
115
116 *offp = poff;
117 *lenp = plen;
118}
119
120static void
121iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
122{
123 struct iomap_page *iop = to_iomap_page(page);
124 struct inode *inode = page->mapping->host;
125 unsigned first = off >> inode->i_blkbits;
126 unsigned last = (off + len - 1) >> inode->i_blkbits;
127 unsigned int i;
128 bool uptodate = true;
129
130 if (iop) {
131 for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
132 if (i >= first && i <= last)
133 set_bit(i, iop->uptodate);
134 else if (!test_bit(i, iop->uptodate))
135 uptodate = false;
136 }
137 }
138
139 if (uptodate && !PageError(page))
140 SetPageUptodate(page);
141}
142
143static void
144iomap_read_finish(struct iomap_page *iop, struct page *page)
145{
146 if (!iop || atomic_dec_and_test(&iop->read_count))
147 unlock_page(page);
148}
149
150static void
151iomap_read_page_end_io(struct bio_vec *bvec, int error)
152{
153 struct page *page = bvec->bv_page;
154 struct iomap_page *iop = to_iomap_page(page);
155
156 if (unlikely(error)) {
157 ClearPageUptodate(page);
158 SetPageError(page);
159 } else {
160 iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
161 }
162
163 iomap_read_finish(iop, page);
164}
165
166static void
167iomap_read_end_io(struct bio *bio)
168{
169 int error = blk_status_to_errno(bio->bi_status);
170 struct bio_vec *bvec;
171 struct bvec_iter_all iter_all;
172
173 bio_for_each_segment_all(bvec, bio, iter_all)
174 iomap_read_page_end_io(bvec, error);
175 bio_put(bio);
176}
177
178struct iomap_readpage_ctx {
179 struct page *cur_page;
180 bool cur_page_in_bio;
181 bool is_readahead;
182 struct bio *bio;
183 struct list_head *pages;
184};
185
186static void
187iomap_read_inline_data(struct inode *inode, struct page *page,
188 struct iomap *iomap)
189{
190 size_t size = i_size_read(inode);
191 void *addr;
192
193 if (PageUptodate(page))
194 return;
195
196 BUG_ON(page->index);
197 BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
198
199 addr = kmap_atomic(page);
200 memcpy(addr, iomap->inline_data, size);
201 memset(addr + size, 0, PAGE_SIZE - size);
202 kunmap_atomic(addr);
203 SetPageUptodate(page);
204}
205
206static loff_t
207iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
208 struct iomap *iomap)
209{
210 struct iomap_readpage_ctx *ctx = data;
211 struct page *page = ctx->cur_page;
212 struct iomap_page *iop = iomap_page_create(inode, page);
213 bool same_page = false, is_contig = false;
214 loff_t orig_pos = pos;
215 unsigned poff, plen;
216 sector_t sector;
217
218 if (iomap->type == IOMAP_INLINE) {
219 WARN_ON_ONCE(pos);
220 iomap_read_inline_data(inode, page, iomap);
221 return PAGE_SIZE;
222 }
223
224 /* zero post-eof blocks as the page may be mapped */
225 iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
226 if (plen == 0)
227 goto done;
228
229 if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) {
230 zero_user(page, poff, plen);
231 iomap_set_range_uptodate(page, poff, plen);
232 goto done;
233 }
234
235 ctx->cur_page_in_bio = true;
236
237 /*
238 * Try to merge into a previous segment if we can.
239 */
240 sector = iomap_sector(iomap, pos);
241 if (ctx->bio && bio_end_sector(ctx->bio) == sector)
242 is_contig = true;
243
244 if (is_contig &&
245 __bio_try_merge_page(ctx->bio, page, plen, poff, &same_page)) {
246 if (!same_page && iop)
247 atomic_inc(&iop->read_count);
248 goto done;
249 }
250
251 /*
252 * If we start a new segment we need to increase the read count, and we
253 * need to do so before submitting any previous full bio to make sure
254 * that we don't prematurely unlock the page.
255 */
256 if (iop)
257 atomic_inc(&iop->read_count);
258
259 if (!ctx->bio || !is_contig || bio_full(ctx->bio, plen)) {
260 gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
261 int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
262
263 if (ctx->bio)
264 submit_bio(ctx->bio);
265
266 if (ctx->is_readahead) /* same as readahead_gfp_mask */
267 gfp |= __GFP_NORETRY | __GFP_NOWARN;
268 ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
269 ctx->bio->bi_opf = REQ_OP_READ;
270 if (ctx->is_readahead)
271 ctx->bio->bi_opf |= REQ_RAHEAD;
272 ctx->bio->bi_iter.bi_sector = sector;
273 bio_set_dev(ctx->bio, iomap->bdev);
274 ctx->bio->bi_end_io = iomap_read_end_io;
275 }
276
277 bio_add_page(ctx->bio, page, plen, poff);
278done:
279 /*
280 * Move the caller beyond our range so that it keeps making progress.
281 * For that we have to include any leading non-uptodate ranges, but
282 * we can skip trailing ones as they will be handled in the next
283 * iteration.
284 */
285 return pos - orig_pos + plen;
286}
287
288int
289iomap_readpage(struct page *page, const struct iomap_ops *ops)
290{
291 struct iomap_readpage_ctx ctx = { .cur_page = page };
292 struct inode *inode = page->mapping->host;
293 unsigned poff;
294 loff_t ret;
295
296 for (poff = 0; poff < PAGE_SIZE; poff += ret) {
297 ret = iomap_apply(inode, page_offset(page) + poff,
298 PAGE_SIZE - poff, 0, ops, &ctx,
299 iomap_readpage_actor);
300 if (ret <= 0) {
301 WARN_ON_ONCE(ret == 0);
302 SetPageError(page);
303 break;
304 }
305 }
306
307 if (ctx.bio) {
308 submit_bio(ctx.bio);
309 WARN_ON_ONCE(!ctx.cur_page_in_bio);
310 } else {
311 WARN_ON_ONCE(ctx.cur_page_in_bio);
312 unlock_page(page);
313 }
314
315 /*
316 * Just like mpage_readpages and block_read_full_page we always
317 * return 0 and just mark the page as PageError on errors. This
318 * should be cleaned up all through the stack eventually.
319 */
320 return 0;
321}
322EXPORT_SYMBOL_GPL(iomap_readpage);
323
324static struct page *
325iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
326 loff_t length, loff_t *done)
327{
328 while (!list_empty(pages)) {
329 struct page *page = lru_to_page(pages);
330
331 if (page_offset(page) >= (u64)pos + length)
332 break;
333
334 list_del(&page->lru);
335 if (!add_to_page_cache_lru(page, inode->i_mapping, page->index,
336 GFP_NOFS))
337 return page;
338
339 /*
340 * If we already have a page in the page cache at index we are
341 * done. Upper layers don't care if it is uptodate after the
342 * readpages call itself as every page gets checked again once
343 * actually needed.
344 */
345 *done += PAGE_SIZE;
346 put_page(page);
347 }
348
349 return NULL;
350}
351
352static loff_t
353iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
354 void *data, struct iomap *iomap)
355{
356 struct iomap_readpage_ctx *ctx = data;
357 loff_t done, ret;
358
359 for (done = 0; done < length; done += ret) {
360 if (ctx->cur_page && offset_in_page(pos + done) == 0) {
361 if (!ctx->cur_page_in_bio)
362 unlock_page(ctx->cur_page);
363 put_page(ctx->cur_page);
364 ctx->cur_page = NULL;
365 }
366 if (!ctx->cur_page) {
367 ctx->cur_page = iomap_next_page(inode, ctx->pages,
368 pos, length, &done);
369 if (!ctx->cur_page)
370 break;
371 ctx->cur_page_in_bio = false;
372 }
373 ret = iomap_readpage_actor(inode, pos + done, length - done,
374 ctx, iomap);
375 }
376
377 return done;
378}
379
380int
381iomap_readpages(struct address_space *mapping, struct list_head *pages,
382 unsigned nr_pages, const struct iomap_ops *ops)
383{
384 struct iomap_readpage_ctx ctx = {
385 .pages = pages,
386 .is_readahead = true,
387 };
388 loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
389 loff_t last = page_offset(list_entry(pages->next, struct page, lru));
390 loff_t length = last - pos + PAGE_SIZE, ret = 0;
391
392 while (length > 0) {
393 ret = iomap_apply(mapping->host, pos, length, 0, ops,
394 &ctx, iomap_readpages_actor);
395 if (ret <= 0) {
396 WARN_ON_ONCE(ret == 0);
397 goto done;
398 }
399 pos += ret;
400 length -= ret;
401 }
402 ret = 0;
403done:
404 if (ctx.bio)
405 submit_bio(ctx.bio);
406 if (ctx.cur_page) {
407 if (!ctx.cur_page_in_bio)
408 unlock_page(ctx.cur_page);
409 put_page(ctx.cur_page);
410 }
411
412 /*
413 * Check that we didn't lose a page due to the arcance calling
414 * conventions..
415 */
416 WARN_ON_ONCE(!ret && !list_empty(ctx.pages));
417 return ret;
418}
419EXPORT_SYMBOL_GPL(iomap_readpages);
420
421/*
422 * iomap_is_partially_uptodate checks whether blocks within a page are
423 * uptodate or not.
424 *
425 * Returns true if all blocks which correspond to a file portion
426 * we want to read within the page are uptodate.
427 */
428int
429iomap_is_partially_uptodate(struct page *page, unsigned long from,
430 unsigned long count)
431{
432 struct iomap_page *iop = to_iomap_page(page);
433 struct inode *inode = page->mapping->host;
434 unsigned len, first, last;
435 unsigned i;
436
437 /* Limit range to one page */
438 len = min_t(unsigned, PAGE_SIZE - from, count);
439
440 /* First and last blocks in range within page */
441 first = from >> inode->i_blkbits;
442 last = (from + len - 1) >> inode->i_blkbits;
443
444 if (iop) {
445 for (i = first; i <= last; i++)
446 if (!test_bit(i, iop->uptodate))
447 return 0;
448 return 1;
449 }
450
451 return 0;
452}
453EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
454
455int
456iomap_releasepage(struct page *page, gfp_t gfp_mask)
457{
458 /*
459 * mm accommodates an old ext3 case where clean pages might not have had
460 * the dirty bit cleared. Thus, it can send actual dirty pages to
461 * ->releasepage() via shrink_active_list(), skip those here.
462 */
463 if (PageDirty(page) || PageWriteback(page))
464 return 0;
465 iomap_page_release(page);
466 return 1;
467}
468EXPORT_SYMBOL_GPL(iomap_releasepage);
469
470void
471iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
472{
473 /*
474 * If we are invalidating the entire page, clear the dirty state from it
475 * and release it to avoid unnecessary buildup of the LRU.
476 */
477 if (offset == 0 && len == PAGE_SIZE) {
478 WARN_ON_ONCE(PageWriteback(page));
479 cancel_dirty_page(page);
480 iomap_page_release(page);
481 }
482}
483EXPORT_SYMBOL_GPL(iomap_invalidatepage);
484
485#ifdef CONFIG_MIGRATION
486int
487iomap_migrate_page(struct address_space *mapping, struct page *newpage,
488 struct page *page, enum migrate_mode mode)
489{
490 int ret;
491
492 ret = migrate_page_move_mapping(mapping, newpage, page, 0);
493 if (ret != MIGRATEPAGE_SUCCESS)
494 return ret;
495
496 if (page_has_private(page)) {
497 ClearPagePrivate(page);
498 get_page(newpage);
499 set_page_private(newpage, page_private(page));
500 set_page_private(page, 0);
501 put_page(page);
502 SetPagePrivate(newpage);
503 }
504
505 if (mode != MIGRATE_SYNC_NO_COPY)
506 migrate_page_copy(newpage, page);
507 else
508 migrate_page_states(newpage, page);
509 return MIGRATEPAGE_SUCCESS;
510}
511EXPORT_SYMBOL_GPL(iomap_migrate_page);
512#endif /* CONFIG_MIGRATION */
513
514static void
515iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
516{
517 loff_t i_size = i_size_read(inode);
518
519 /*
520 * Only truncate newly allocated pages beyoned EOF, even if the
521 * write started inside the existing inode size.
522 */
523 if (pos + len > i_size)
524 truncate_pagecache_range(inode, max(pos, i_size), pos + len);
525}
526
527static int
528iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page,
529 unsigned poff, unsigned plen, unsigned from, unsigned to,
530 struct iomap *iomap)
531{
532 struct bio_vec bvec;
533 struct bio bio;
534
535 if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) {
536 zero_user_segments(page, poff, from, to, poff + plen);
537 iomap_set_range_uptodate(page, poff, plen);
538 return 0;
539 }
540
541 bio_init(&bio, &bvec, 1);
542 bio.bi_opf = REQ_OP_READ;
543 bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
544 bio_set_dev(&bio, iomap->bdev);
545 __bio_add_page(&bio, page, plen, poff);
546 return submit_bio_wait(&bio);
547}
548
549static int
550__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
551 struct page *page, struct iomap *iomap)
552{
553 struct iomap_page *iop = iomap_page_create(inode, page);
554 loff_t block_size = i_blocksize(inode);
555 loff_t block_start = pos & ~(block_size - 1);
556 loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
557 unsigned from = offset_in_page(pos), to = from + len, poff, plen;
558 int status = 0;
559
560 if (PageUptodate(page))
561 return 0;
562
563 do {
564 iomap_adjust_read_range(inode, iop, &block_start,
565 block_end - block_start, &poff, &plen);
566 if (plen == 0)
567 break;
568
569 if ((from > poff && from < poff + plen) ||
570 (to > poff && to < poff + plen)) {
571 status = iomap_read_page_sync(inode, block_start, page,
572 poff, plen, from, to, iomap);
573 if (status)
574 break;
575 }
576
577 } while ((block_start += plen) < block_end);
578
579 return status;
580}
581
582static int
583iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
584 struct page **pagep, struct iomap *iomap)
585{
586 const struct iomap_page_ops *page_ops = iomap->page_ops;
587 pgoff_t index = pos >> PAGE_SHIFT;
588 struct page *page;
589 int status = 0;
590
591 BUG_ON(pos + len > iomap->offset + iomap->length);
592
593 if (fatal_signal_pending(current))
594 return -EINTR;
595
596 if (page_ops && page_ops->page_prepare) {
597 status = page_ops->page_prepare(inode, pos, len, iomap);
598 if (status)
599 return status;
600 }
601
602 page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
603 if (!page) {
604 status = -ENOMEM;
605 goto out_no_page;
606 }
607
608 if (iomap->type == IOMAP_INLINE)
609 iomap_read_inline_data(inode, page, iomap);
610 else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
611 status = __block_write_begin_int(page, pos, len, NULL, iomap);
612 else
613 status = __iomap_write_begin(inode, pos, len, page, iomap);
614
615 if (unlikely(status))
616 goto out_unlock;
617
618 *pagep = page;
619 return 0;
620
621out_unlock:
622 unlock_page(page);
623 put_page(page);
624 iomap_write_failed(inode, pos, len);
625
626out_no_page:
627 if (page_ops && page_ops->page_done)
628 page_ops->page_done(inode, pos, 0, NULL, iomap);
629 return status;
630}
631
632int
633iomap_set_page_dirty(struct page *page)
634{
635 struct address_space *mapping = page_mapping(page);
636 int newly_dirty;
637
638 if (unlikely(!mapping))
639 return !TestSetPageDirty(page);
640
641 /*
642 * Lock out page->mem_cgroup migration to keep PageDirty
643 * synchronized with per-memcg dirty page counters.
644 */
645 lock_page_memcg(page);
646 newly_dirty = !TestSetPageDirty(page);
647 if (newly_dirty)
648 __set_page_dirty(page, mapping, 0);
649 unlock_page_memcg(page);
650
651 if (newly_dirty)
652 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
653 return newly_dirty;
654}
655EXPORT_SYMBOL_GPL(iomap_set_page_dirty);
656
657static int
658__iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
659 unsigned copied, struct page *page, struct iomap *iomap)
660{
661 flush_dcache_page(page);
662
663 /*
664 * The blocks that were entirely written will now be uptodate, so we
665 * don't have to worry about a readpage reading them and overwriting a
666 * partial write. However if we have encountered a short write and only
667 * partially written into a block, it will not be marked uptodate, so a
668 * readpage might come in and destroy our partial write.
669 *
670 * Do the simplest thing, and just treat any short write to a non
671 * uptodate page as a zero-length write, and force the caller to redo
672 * the whole thing.
673 */
674 if (unlikely(copied < len && !PageUptodate(page)))
675 return 0;
676 iomap_set_range_uptodate(page, offset_in_page(pos), len);
677 iomap_set_page_dirty(page);
678 return copied;
679}
680
681static int
682iomap_write_end_inline(struct inode *inode, struct page *page,
683 struct iomap *iomap, loff_t pos, unsigned copied)
684{
685 void *addr;
686
687 WARN_ON_ONCE(!PageUptodate(page));
688 BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
689
690 addr = kmap_atomic(page);
691 memcpy(iomap->inline_data + pos, addr + pos, copied);
692 kunmap_atomic(addr);
693
694 mark_inode_dirty(inode);
695 return copied;
696}
697
698static int
699iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
700 unsigned copied, struct page *page, struct iomap *iomap)
701{
702 const struct iomap_page_ops *page_ops = iomap->page_ops;
703 loff_t old_size = inode->i_size;
704 int ret;
705
706 if (iomap->type == IOMAP_INLINE) {
707 ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
708 } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
709 ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
710 page, NULL);
711 } else {
712 ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
713 }
714
715 /*
716 * Update the in-memory inode size after copying the data into the page
717 * cache. It's up to the file system to write the updated size to disk,
718 * preferably after I/O completion so that no stale data is exposed.
719 */
720 if (pos + ret > old_size) {
721 i_size_write(inode, pos + ret);
722 iomap->flags |= IOMAP_F_SIZE_CHANGED;
723 }
724 unlock_page(page);
725
726 if (old_size < pos)
727 pagecache_isize_extended(inode, old_size, pos);
728 if (page_ops && page_ops->page_done)
729 page_ops->page_done(inode, pos, ret, page, iomap);
730 put_page(page);
731
732 if (ret < len)
733 iomap_write_failed(inode, pos, len);
734 return ret;
735}
736
737static loff_t
738iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
739 struct iomap *iomap)
740{
741 struct iov_iter *i = data;
742 long status = 0;
743 ssize_t written = 0;
744 unsigned int flags = AOP_FLAG_NOFS;
745
746 do {
747 struct page *page;
748 unsigned long offset; /* Offset into pagecache page */
749 unsigned long bytes; /* Bytes to write to page */
750 size_t copied; /* Bytes copied from user */
751
752 offset = offset_in_page(pos);
753 bytes = min_t(unsigned long, PAGE_SIZE - offset,
754 iov_iter_count(i));
755again:
756 if (bytes > length)
757 bytes = length;
758
759 /*
760 * Bring in the user page that we will copy from _first_.
761 * Otherwise there's a nasty deadlock on copying from the
762 * same page as we're writing to, without it being marked
763 * up-to-date.
764 *
765 * Not only is this an optimisation, but it is also required
766 * to check that the address is actually valid, when atomic
767 * usercopies are used, below.
768 */
769 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
770 status = -EFAULT;
771 break;
772 }
773
774 status = iomap_write_begin(inode, pos, bytes, flags, &page,
775 iomap);
776 if (unlikely(status))
777 break;
778
779 if (mapping_writably_mapped(inode->i_mapping))
780 flush_dcache_page(page);
781
782 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
783
784 flush_dcache_page(page);
785
786 status = iomap_write_end(inode, pos, bytes, copied, page,
787 iomap);
788 if (unlikely(status < 0))
789 break;
790 copied = status;
791
792 cond_resched();
793
794 iov_iter_advance(i, copied);
795 if (unlikely(copied == 0)) {
796 /*
797 * If we were unable to copy any data at all, we must
798 * fall back to a single segment length write.
799 *
800 * If we didn't fallback here, we could livelock
801 * because not all segments in the iov can be copied at
802 * once without a pagefault.
803 */
804 bytes = min_t(unsigned long, PAGE_SIZE - offset,
805 iov_iter_single_seg_count(i));
806 goto again;
807 }
808 pos += copied;
809 written += copied;
810 length -= copied;
811
812 balance_dirty_pages_ratelimited(inode->i_mapping);
813 } while (iov_iter_count(i) && length);
814
815 return written ? written : status;
816}
817
818ssize_t
819iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
820 const struct iomap_ops *ops)
821{
822 struct inode *inode = iocb->ki_filp->f_mapping->host;
823 loff_t pos = iocb->ki_pos, ret = 0, written = 0;
824
825 while (iov_iter_count(iter)) {
826 ret = iomap_apply(inode, pos, iov_iter_count(iter),
827 IOMAP_WRITE, ops, iter, iomap_write_actor);
828 if (ret <= 0)
829 break;
830 pos += ret;
831 written += ret;
832 }
833
834 return written ? written : ret;
835}
836EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
837
838static struct page *
839__iomap_read_page(struct inode *inode, loff_t offset)
840{
841 struct address_space *mapping = inode->i_mapping;
842 struct page *page;
843
844 page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
845 if (IS_ERR(page))
846 return page;
847 if (!PageUptodate(page)) {
848 put_page(page);
849 return ERR_PTR(-EIO);
850 }
851 return page;
852}
853
854static loff_t
855iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
856 struct iomap *iomap)
857{
858 long status = 0;
859 ssize_t written = 0;
860
861 do {
862 struct page *page, *rpage;
863 unsigned long offset; /* Offset into pagecache page */
864 unsigned long bytes; /* Bytes to write to page */
865
866 offset = offset_in_page(pos);
867 bytes = min_t(loff_t, PAGE_SIZE - offset, length);
868
869 rpage = __iomap_read_page(inode, pos);
870 if (IS_ERR(rpage))
871 return PTR_ERR(rpage);
872
873 status = iomap_write_begin(inode, pos, bytes,
874 AOP_FLAG_NOFS, &page, iomap);
875 put_page(rpage);
876 if (unlikely(status))
877 return status;
878
879 WARN_ON_ONCE(!PageUptodate(page));
880
881 status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
882 if (unlikely(status <= 0)) {
883 if (WARN_ON_ONCE(status == 0))
884 return -EIO;
885 return status;
886 }
887
888 cond_resched();
889
890 pos += status;
891 written += status;
892 length -= status;
893
894 balance_dirty_pages_ratelimited(inode->i_mapping);
895 } while (length);
896
897 return written;
898}
899
900int
901iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
902 const struct iomap_ops *ops)
903{
904 loff_t ret;
905
906 while (len) {
907 ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
908 iomap_dirty_actor);
909 if (ret <= 0)
910 return ret;
911 pos += ret;
912 len -= ret;
913 }
914
915 return 0;
916}
917EXPORT_SYMBOL_GPL(iomap_file_dirty);
918
919static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
920 unsigned bytes, struct iomap *iomap)
921{
922 struct page *page;
923 int status;
924
925 status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page,
926 iomap);
927 if (status)
928 return status;
929
930 zero_user(page, offset, bytes);
931 mark_page_accessed(page);
932
933 return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
934}
935
936static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
937 struct iomap *iomap)
938{
939 return __dax_zero_page_range(iomap->bdev, iomap->dax_dev,
940 iomap_sector(iomap, pos & PAGE_MASK), offset, bytes);
941}
942
943static loff_t
944iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
945 void *data, struct iomap *iomap)
946{
947 bool *did_zero = data;
948 loff_t written = 0;
949 int status;
950
951 /* already zeroed? we're done. */
952 if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
953 return count;
954
955 do {
956 unsigned offset, bytes;
957
958 offset = offset_in_page(pos);
959 bytes = min_t(loff_t, PAGE_SIZE - offset, count);
960
961 if (IS_DAX(inode))
962 status = iomap_dax_zero(pos, offset, bytes, iomap);
963 else
964 status = iomap_zero(inode, pos, offset, bytes, iomap);
965 if (status < 0)
966 return status;
967
968 pos += bytes;
969 count -= bytes;
970 written += bytes;
971 if (did_zero)
972 *did_zero = true;
973 } while (count > 0);
974
975 return written;
976}
977
978int
979iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
980 const struct iomap_ops *ops)
981{
982 loff_t ret;
983
984 while (len > 0) {
985 ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
986 ops, did_zero, iomap_zero_range_actor);
987 if (ret <= 0)
988 return ret;
989
990 pos += ret;
991 len -= ret;
992 }
993
994 return 0;
995}
996EXPORT_SYMBOL_GPL(iomap_zero_range);
997
998int
999iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
1000 const struct iomap_ops *ops)
1001{
1002 unsigned int blocksize = i_blocksize(inode);
1003 unsigned int off = pos & (blocksize - 1);
1004
1005 /* Block boundary? Nothing to do */
1006 if (!off)
1007 return 0;
1008 return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
1009}
1010EXPORT_SYMBOL_GPL(iomap_truncate_page);
1011
1012static loff_t
1013iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
1014 void *data, struct iomap *iomap)
1015{
1016 struct page *page = data;
1017 int ret;
1018
1019 if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
1020 ret = __block_write_begin_int(page, pos, length, NULL, iomap);
1021 if (ret)
1022 return ret;
1023 block_commit_write(page, 0, length);
1024 } else {
1025 WARN_ON_ONCE(!PageUptodate(page));
1026 iomap_page_create(inode, page);
1027 set_page_dirty(page);
1028 }
1029
1030 return length;
1031}
1032
1033vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
1034{
1035 struct page *page = vmf->page;
1036 struct inode *inode = file_inode(vmf->vma->vm_file);
1037 unsigned long length;
1038 loff_t offset, size;
1039 ssize_t ret;
1040
1041 lock_page(page);
1042 size = i_size_read(inode);
1043 if ((page->mapping != inode->i_mapping) ||
1044 (page_offset(page) > size)) {
1045 /* We overload EFAULT to mean page got truncated */
1046 ret = -EFAULT;
1047 goto out_unlock;
1048 }
1049
1050 /* page is wholly or partially inside EOF */
1051 if (((page->index + 1) << PAGE_SHIFT) > size)
1052 length = offset_in_page(size);
1053 else
1054 length = PAGE_SIZE;
1055
1056 offset = page_offset(page);
1057 while (length > 0) {
1058 ret = iomap_apply(inode, offset, length,
1059 IOMAP_WRITE | IOMAP_FAULT, ops, page,
1060 iomap_page_mkwrite_actor);
1061 if (unlikely(ret <= 0))
1062 goto out_unlock;
1063 offset += ret;
1064 length -= ret;
1065 }
1066
1067 wait_for_stable_page(page);
1068 return VM_FAULT_LOCKED;
1069out_unlock:
1070 unlock_page(page);
1071 return block_page_mkwrite_return(ret);
1072}
1073EXPORT_SYMBOL_GPL(iomap_page_mkwrite);