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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (C) 2016-2019 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/list_sort.h>
16#include <linux/swap.h>
17#include <linux/bio.h>
18#include <linux/sched/signal.h>
19#include <linux/migrate.h>
20#include "trace.h"
21
22#include "../internal.h"
23
24/*
25 * Structure allocated for each page when block size < PAGE_SIZE to track
26 * sub-page uptodate status and I/O completions.
27 */
28struct iomap_page {
29 atomic_t read_count;
30 atomic_t write_count;
31 spinlock_t uptodate_lock;
32 DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
33};
34
35static inline struct iomap_page *to_iomap_page(struct page *page)
36{
37 if (page_has_private(page))
38 return (struct iomap_page *)page_private(page);
39 return NULL;
40}
41
42static struct bio_set iomap_ioend_bioset;
43
44static struct iomap_page *
45iomap_page_create(struct inode *inode, struct page *page)
46{
47 struct iomap_page *iop = to_iomap_page(page);
48
49 if (iop || i_blocksize(inode) == PAGE_SIZE)
50 return iop;
51
52 iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
53 atomic_set(&iop->read_count, 0);
54 atomic_set(&iop->write_count, 0);
55 spin_lock_init(&iop->uptodate_lock);
56 bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
57
58 /*
59 * migrate_page_move_mapping() assumes that pages with private data have
60 * their count elevated by 1.
61 */
62 attach_page_private(page, iop);
63 return iop;
64}
65
66static void
67iomap_page_release(struct page *page)
68{
69 struct iomap_page *iop = detach_page_private(page);
70
71 if (!iop)
72 return;
73 WARN_ON_ONCE(atomic_read(&iop->read_count));
74 WARN_ON_ONCE(atomic_read(&iop->write_count));
75 kfree(iop);
76}
77
78/*
79 * Calculate the range inside the page that we actually need to read.
80 */
81static void
82iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
83 loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
84{
85 loff_t orig_pos = *pos;
86 loff_t isize = i_size_read(inode);
87 unsigned block_bits = inode->i_blkbits;
88 unsigned block_size = (1 << block_bits);
89 unsigned poff = offset_in_page(*pos);
90 unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
91 unsigned first = poff >> block_bits;
92 unsigned last = (poff + plen - 1) >> block_bits;
93
94 /*
95 * If the block size is smaller than the page size we need to check the
96 * per-block uptodate status and adjust the offset and length if needed
97 * to avoid reading in already uptodate ranges.
98 */
99 if (iop) {
100 unsigned int i;
101
102 /* move forward for each leading block marked uptodate */
103 for (i = first; i <= last; i++) {
104 if (!test_bit(i, iop->uptodate))
105 break;
106 *pos += block_size;
107 poff += block_size;
108 plen -= block_size;
109 first++;
110 }
111
112 /* truncate len if we find any trailing uptodate block(s) */
113 for ( ; i <= last; i++) {
114 if (test_bit(i, iop->uptodate)) {
115 plen -= (last - i + 1) * block_size;
116 last = i - 1;
117 break;
118 }
119 }
120 }
121
122 /*
123 * If the extent spans the block that contains the i_size we need to
124 * handle both halves separately so that we properly zero data in the
125 * page cache for blocks that are entirely outside of i_size.
126 */
127 if (orig_pos <= isize && orig_pos + length > isize) {
128 unsigned end = offset_in_page(isize - 1) >> block_bits;
129
130 if (first <= end && last > end)
131 plen -= (last - end) * block_size;
132 }
133
134 *offp = poff;
135 *lenp = plen;
136}
137
138static void
139iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
140{
141 struct iomap_page *iop = to_iomap_page(page);
142 struct inode *inode = page->mapping->host;
143 unsigned first = off >> inode->i_blkbits;
144 unsigned last = (off + len - 1) >> inode->i_blkbits;
145 bool uptodate = true;
146 unsigned long flags;
147 unsigned int i;
148
149 spin_lock_irqsave(&iop->uptodate_lock, flags);
150 for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
151 if (i >= first && i <= last)
152 set_bit(i, iop->uptodate);
153 else if (!test_bit(i, iop->uptodate))
154 uptodate = false;
155 }
156
157 if (uptodate)
158 SetPageUptodate(page);
159 spin_unlock_irqrestore(&iop->uptodate_lock, flags);
160}
161
162static void
163iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
164{
165 if (PageError(page))
166 return;
167
168 if (page_has_private(page))
169 iomap_iop_set_range_uptodate(page, off, len);
170 else
171 SetPageUptodate(page);
172}
173
174static void
175iomap_read_finish(struct iomap_page *iop, struct page *page)
176{
177 if (!iop || atomic_dec_and_test(&iop->read_count))
178 unlock_page(page);
179}
180
181static void
182iomap_read_page_end_io(struct bio_vec *bvec, int error)
183{
184 struct page *page = bvec->bv_page;
185 struct iomap_page *iop = to_iomap_page(page);
186
187 if (unlikely(error)) {
188 ClearPageUptodate(page);
189 SetPageError(page);
190 } else {
191 iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
192 }
193
194 iomap_read_finish(iop, page);
195}
196
197static void
198iomap_read_end_io(struct bio *bio)
199{
200 int error = blk_status_to_errno(bio->bi_status);
201 struct bio_vec *bvec;
202 struct bvec_iter_all iter_all;
203
204 bio_for_each_segment_all(bvec, bio, iter_all)
205 iomap_read_page_end_io(bvec, error);
206 bio_put(bio);
207}
208
209struct iomap_readpage_ctx {
210 struct page *cur_page;
211 bool cur_page_in_bio;
212 struct bio *bio;
213 struct readahead_control *rac;
214};
215
216static void
217iomap_read_inline_data(struct inode *inode, struct page *page,
218 struct iomap *iomap)
219{
220 size_t size = i_size_read(inode);
221 void *addr;
222
223 if (PageUptodate(page))
224 return;
225
226 BUG_ON(page->index);
227 BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
228
229 addr = kmap_atomic(page);
230 memcpy(addr, iomap->inline_data, size);
231 memset(addr + size, 0, PAGE_SIZE - size);
232 kunmap_atomic(addr);
233 SetPageUptodate(page);
234}
235
236static inline bool iomap_block_needs_zeroing(struct inode *inode,
237 struct iomap *iomap, loff_t pos)
238{
239 return iomap->type != IOMAP_MAPPED ||
240 (iomap->flags & IOMAP_F_NEW) ||
241 pos >= i_size_read(inode);
242}
243
244static loff_t
245iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
246 struct iomap *iomap, struct iomap *srcmap)
247{
248 struct iomap_readpage_ctx *ctx = data;
249 struct page *page = ctx->cur_page;
250 struct iomap_page *iop = iomap_page_create(inode, page);
251 bool same_page = false, is_contig = false;
252 loff_t orig_pos = pos;
253 unsigned poff, plen;
254 sector_t sector;
255
256 if (iomap->type == IOMAP_INLINE) {
257 WARN_ON_ONCE(pos);
258 iomap_read_inline_data(inode, page, iomap);
259 return PAGE_SIZE;
260 }
261
262 /* zero post-eof blocks as the page may be mapped */
263 iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
264 if (plen == 0)
265 goto done;
266
267 if (iomap_block_needs_zeroing(inode, iomap, pos)) {
268 zero_user(page, poff, plen);
269 iomap_set_range_uptodate(page, poff, plen);
270 goto done;
271 }
272
273 ctx->cur_page_in_bio = true;
274
275 /*
276 * Try to merge into a previous segment if we can.
277 */
278 sector = iomap_sector(iomap, pos);
279 if (ctx->bio && bio_end_sector(ctx->bio) == sector)
280 is_contig = true;
281
282 if (is_contig &&
283 __bio_try_merge_page(ctx->bio, page, plen, poff, &same_page)) {
284 if (!same_page && iop)
285 atomic_inc(&iop->read_count);
286 goto done;
287 }
288
289 /*
290 * If we start a new segment we need to increase the read count, and we
291 * need to do so before submitting any previous full bio to make sure
292 * that we don't prematurely unlock the page.
293 */
294 if (iop)
295 atomic_inc(&iop->read_count);
296
297 if (!ctx->bio || !is_contig || bio_full(ctx->bio, plen)) {
298 gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
299 gfp_t orig_gfp = gfp;
300 int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
301
302 if (ctx->bio)
303 submit_bio(ctx->bio);
304
305 if (ctx->rac) /* same as readahead_gfp_mask */
306 gfp |= __GFP_NORETRY | __GFP_NOWARN;
307 ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
308 /*
309 * If the bio_alloc fails, try it again for a single page to
310 * avoid having to deal with partial page reads. This emulates
311 * what do_mpage_readpage does.
312 */
313 if (!ctx->bio)
314 ctx->bio = bio_alloc(orig_gfp, 1);
315 ctx->bio->bi_opf = REQ_OP_READ;
316 if (ctx->rac)
317 ctx->bio->bi_opf |= REQ_RAHEAD;
318 ctx->bio->bi_iter.bi_sector = sector;
319 bio_set_dev(ctx->bio, iomap->bdev);
320 ctx->bio->bi_end_io = iomap_read_end_io;
321 }
322
323 bio_add_page(ctx->bio, page, plen, poff);
324done:
325 /*
326 * Move the caller beyond our range so that it keeps making progress.
327 * For that we have to include any leading non-uptodate ranges, but
328 * we can skip trailing ones as they will be handled in the next
329 * iteration.
330 */
331 return pos - orig_pos + plen;
332}
333
334int
335iomap_readpage(struct page *page, const struct iomap_ops *ops)
336{
337 struct iomap_readpage_ctx ctx = { .cur_page = page };
338 struct inode *inode = page->mapping->host;
339 unsigned poff;
340 loff_t ret;
341
342 trace_iomap_readpage(page->mapping->host, 1);
343
344 for (poff = 0; poff < PAGE_SIZE; poff += ret) {
345 ret = iomap_apply(inode, page_offset(page) + poff,
346 PAGE_SIZE - poff, 0, ops, &ctx,
347 iomap_readpage_actor);
348 if (ret <= 0) {
349 WARN_ON_ONCE(ret == 0);
350 SetPageError(page);
351 break;
352 }
353 }
354
355 if (ctx.bio) {
356 submit_bio(ctx.bio);
357 WARN_ON_ONCE(!ctx.cur_page_in_bio);
358 } else {
359 WARN_ON_ONCE(ctx.cur_page_in_bio);
360 unlock_page(page);
361 }
362
363 /*
364 * Just like mpage_readahead and block_read_full_page we always
365 * return 0 and just mark the page as PageError on errors. This
366 * should be cleaned up all through the stack eventually.
367 */
368 return 0;
369}
370EXPORT_SYMBOL_GPL(iomap_readpage);
371
372static loff_t
373iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length,
374 void *data, struct iomap *iomap, struct iomap *srcmap)
375{
376 struct iomap_readpage_ctx *ctx = data;
377 loff_t done, ret;
378
379 for (done = 0; done < length; done += ret) {
380 if (ctx->cur_page && offset_in_page(pos + done) == 0) {
381 if (!ctx->cur_page_in_bio)
382 unlock_page(ctx->cur_page);
383 put_page(ctx->cur_page);
384 ctx->cur_page = NULL;
385 }
386 if (!ctx->cur_page) {
387 ctx->cur_page = readahead_page(ctx->rac);
388 ctx->cur_page_in_bio = false;
389 }
390 ret = iomap_readpage_actor(inode, pos + done, length - done,
391 ctx, iomap, srcmap);
392 }
393
394 return done;
395}
396
397/**
398 * iomap_readahead - Attempt to read pages from a file.
399 * @rac: Describes the pages to be read.
400 * @ops: The operations vector for the filesystem.
401 *
402 * This function is for filesystems to call to implement their readahead
403 * address_space operation.
404 *
405 * Context: The @ops callbacks may submit I/O (eg to read the addresses of
406 * blocks from disc), and may wait for it. The caller may be trying to
407 * access a different page, and so sleeping excessively should be avoided.
408 * It may allocate memory, but should avoid costly allocations. This
409 * function is called with memalloc_nofs set, so allocations will not cause
410 * the filesystem to be reentered.
411 */
412void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
413{
414 struct inode *inode = rac->mapping->host;
415 loff_t pos = readahead_pos(rac);
416 loff_t length = readahead_length(rac);
417 struct iomap_readpage_ctx ctx = {
418 .rac = rac,
419 };
420
421 trace_iomap_readahead(inode, readahead_count(rac));
422
423 while (length > 0) {
424 loff_t ret = iomap_apply(inode, pos, length, 0, ops,
425 &ctx, iomap_readahead_actor);
426 if (ret <= 0) {
427 WARN_ON_ONCE(ret == 0);
428 break;
429 }
430 pos += ret;
431 length -= ret;
432 }
433
434 if (ctx.bio)
435 submit_bio(ctx.bio);
436 if (ctx.cur_page) {
437 if (!ctx.cur_page_in_bio)
438 unlock_page(ctx.cur_page);
439 put_page(ctx.cur_page);
440 }
441}
442EXPORT_SYMBOL_GPL(iomap_readahead);
443
444/*
445 * iomap_is_partially_uptodate checks whether blocks within a page are
446 * uptodate or not.
447 *
448 * Returns true if all blocks which correspond to a file portion
449 * we want to read within the page are uptodate.
450 */
451int
452iomap_is_partially_uptodate(struct page *page, unsigned long from,
453 unsigned long count)
454{
455 struct iomap_page *iop = to_iomap_page(page);
456 struct inode *inode = page->mapping->host;
457 unsigned len, first, last;
458 unsigned i;
459
460 /* Limit range to one page */
461 len = min_t(unsigned, PAGE_SIZE - from, count);
462
463 /* First and last blocks in range within page */
464 first = from >> inode->i_blkbits;
465 last = (from + len - 1) >> inode->i_blkbits;
466
467 if (iop) {
468 for (i = first; i <= last; i++)
469 if (!test_bit(i, iop->uptodate))
470 return 0;
471 return 1;
472 }
473
474 return 0;
475}
476EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
477
478int
479iomap_releasepage(struct page *page, gfp_t gfp_mask)
480{
481 trace_iomap_releasepage(page->mapping->host, page_offset(page),
482 PAGE_SIZE);
483
484 /*
485 * mm accommodates an old ext3 case where clean pages might not have had
486 * the dirty bit cleared. Thus, it can send actual dirty pages to
487 * ->releasepage() via shrink_active_list(), skip those here.
488 */
489 if (PageDirty(page) || PageWriteback(page))
490 return 0;
491 iomap_page_release(page);
492 return 1;
493}
494EXPORT_SYMBOL_GPL(iomap_releasepage);
495
496void
497iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
498{
499 trace_iomap_invalidatepage(page->mapping->host, offset, len);
500
501 /*
502 * If we are invalidating the entire page, clear the dirty state from it
503 * and release it to avoid unnecessary buildup of the LRU.
504 */
505 if (offset == 0 && len == PAGE_SIZE) {
506 WARN_ON_ONCE(PageWriteback(page));
507 cancel_dirty_page(page);
508 iomap_page_release(page);
509 }
510}
511EXPORT_SYMBOL_GPL(iomap_invalidatepage);
512
513#ifdef CONFIG_MIGRATION
514int
515iomap_migrate_page(struct address_space *mapping, struct page *newpage,
516 struct page *page, enum migrate_mode mode)
517{
518 int ret;
519
520 ret = migrate_page_move_mapping(mapping, newpage, page, 0);
521 if (ret != MIGRATEPAGE_SUCCESS)
522 return ret;
523
524 if (page_has_private(page))
525 attach_page_private(newpage, detach_page_private(page));
526
527 if (mode != MIGRATE_SYNC_NO_COPY)
528 migrate_page_copy(newpage, page);
529 else
530 migrate_page_states(newpage, page);
531 return MIGRATEPAGE_SUCCESS;
532}
533EXPORT_SYMBOL_GPL(iomap_migrate_page);
534#endif /* CONFIG_MIGRATION */
535
536enum {
537 IOMAP_WRITE_F_UNSHARE = (1 << 0),
538};
539
540static void
541iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
542{
543 loff_t i_size = i_size_read(inode);
544
545 /*
546 * Only truncate newly allocated pages beyoned EOF, even if the
547 * write started inside the existing inode size.
548 */
549 if (pos + len > i_size)
550 truncate_pagecache_range(inode, max(pos, i_size), pos + len);
551}
552
553static int
554iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff,
555 unsigned plen, struct iomap *iomap)
556{
557 struct bio_vec bvec;
558 struct bio bio;
559
560 bio_init(&bio, &bvec, 1);
561 bio.bi_opf = REQ_OP_READ;
562 bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
563 bio_set_dev(&bio, iomap->bdev);
564 __bio_add_page(&bio, page, plen, poff);
565 return submit_bio_wait(&bio);
566}
567
568static int
569__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
570 struct page *page, struct iomap *srcmap)
571{
572 struct iomap_page *iop = iomap_page_create(inode, page);
573 loff_t block_size = i_blocksize(inode);
574 loff_t block_start = pos & ~(block_size - 1);
575 loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
576 unsigned from = offset_in_page(pos), to = from + len, poff, plen;
577 int status;
578
579 if (PageUptodate(page))
580 return 0;
581
582 do {
583 iomap_adjust_read_range(inode, iop, &block_start,
584 block_end - block_start, &poff, &plen);
585 if (plen == 0)
586 break;
587
588 if (!(flags & IOMAP_WRITE_F_UNSHARE) &&
589 (from <= poff || from >= poff + plen) &&
590 (to <= poff || to >= poff + plen))
591 continue;
592
593 if (iomap_block_needs_zeroing(inode, srcmap, block_start)) {
594 if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE))
595 return -EIO;
596 zero_user_segments(page, poff, from, to, poff + plen);
597 iomap_set_range_uptodate(page, poff, plen);
598 continue;
599 }
600
601 status = iomap_read_page_sync(block_start, page, poff, plen,
602 srcmap);
603 if (status)
604 return status;
605 } while ((block_start += plen) < block_end);
606
607 return 0;
608}
609
610static int
611iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
612 struct page **pagep, struct iomap *iomap, struct iomap *srcmap)
613{
614 const struct iomap_page_ops *page_ops = iomap->page_ops;
615 struct page *page;
616 int status = 0;
617
618 BUG_ON(pos + len > iomap->offset + iomap->length);
619 if (srcmap != iomap)
620 BUG_ON(pos + len > srcmap->offset + srcmap->length);
621
622 if (fatal_signal_pending(current))
623 return -EINTR;
624
625 if (page_ops && page_ops->page_prepare) {
626 status = page_ops->page_prepare(inode, pos, len, iomap);
627 if (status)
628 return status;
629 }
630
631 page = grab_cache_page_write_begin(inode->i_mapping, pos >> PAGE_SHIFT,
632 AOP_FLAG_NOFS);
633 if (!page) {
634 status = -ENOMEM;
635 goto out_no_page;
636 }
637
638 if (srcmap->type == IOMAP_INLINE)
639 iomap_read_inline_data(inode, page, srcmap);
640 else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
641 status = __block_write_begin_int(page, pos, len, NULL, srcmap);
642 else
643 status = __iomap_write_begin(inode, pos, len, flags, page,
644 srcmap);
645
646 if (unlikely(status))
647 goto out_unlock;
648
649 *pagep = page;
650 return 0;
651
652out_unlock:
653 unlock_page(page);
654 put_page(page);
655 iomap_write_failed(inode, pos, len);
656
657out_no_page:
658 if (page_ops && page_ops->page_done)
659 page_ops->page_done(inode, pos, 0, NULL, iomap);
660 return status;
661}
662
663int
664iomap_set_page_dirty(struct page *page)
665{
666 struct address_space *mapping = page_mapping(page);
667 int newly_dirty;
668
669 if (unlikely(!mapping))
670 return !TestSetPageDirty(page);
671
672 /*
673 * Lock out page->mem_cgroup migration to keep PageDirty
674 * synchronized with per-memcg dirty page counters.
675 */
676 lock_page_memcg(page);
677 newly_dirty = !TestSetPageDirty(page);
678 if (newly_dirty)
679 __set_page_dirty(page, mapping, 0);
680 unlock_page_memcg(page);
681
682 if (newly_dirty)
683 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
684 return newly_dirty;
685}
686EXPORT_SYMBOL_GPL(iomap_set_page_dirty);
687
688static int
689__iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
690 unsigned copied, struct page *page)
691{
692 flush_dcache_page(page);
693
694 /*
695 * The blocks that were entirely written will now be uptodate, so we
696 * don't have to worry about a readpage reading them and overwriting a
697 * partial write. However if we have encountered a short write and only
698 * partially written into a block, it will not be marked uptodate, so a
699 * readpage might come in and destroy our partial write.
700 *
701 * Do the simplest thing, and just treat any short write to a non
702 * uptodate page as a zero-length write, and force the caller to redo
703 * the whole thing.
704 */
705 if (unlikely(copied < len && !PageUptodate(page)))
706 return 0;
707 iomap_set_range_uptodate(page, offset_in_page(pos), len);
708 iomap_set_page_dirty(page);
709 return copied;
710}
711
712static int
713iomap_write_end_inline(struct inode *inode, struct page *page,
714 struct iomap *iomap, loff_t pos, unsigned copied)
715{
716 void *addr;
717
718 WARN_ON_ONCE(!PageUptodate(page));
719 BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
720
721 addr = kmap_atomic(page);
722 memcpy(iomap->inline_data + pos, addr + pos, copied);
723 kunmap_atomic(addr);
724
725 mark_inode_dirty(inode);
726 return copied;
727}
728
729static int
730iomap_write_end(struct inode *inode, loff_t pos, unsigned len, unsigned copied,
731 struct page *page, struct iomap *iomap, struct iomap *srcmap)
732{
733 const struct iomap_page_ops *page_ops = iomap->page_ops;
734 loff_t old_size = inode->i_size;
735 int ret;
736
737 if (srcmap->type == IOMAP_INLINE) {
738 ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
739 } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
740 ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
741 page, NULL);
742 } else {
743 ret = __iomap_write_end(inode, pos, len, copied, page);
744 }
745
746 /*
747 * Update the in-memory inode size after copying the data into the page
748 * cache. It's up to the file system to write the updated size to disk,
749 * preferably after I/O completion so that no stale data is exposed.
750 */
751 if (pos + ret > old_size) {
752 i_size_write(inode, pos + ret);
753 iomap->flags |= IOMAP_F_SIZE_CHANGED;
754 }
755 unlock_page(page);
756
757 if (old_size < pos)
758 pagecache_isize_extended(inode, old_size, pos);
759 if (page_ops && page_ops->page_done)
760 page_ops->page_done(inode, pos, ret, page, iomap);
761 put_page(page);
762
763 if (ret < len)
764 iomap_write_failed(inode, pos, len);
765 return ret;
766}
767
768static loff_t
769iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
770 struct iomap *iomap, struct iomap *srcmap)
771{
772 struct iov_iter *i = data;
773 long status = 0;
774 ssize_t written = 0;
775
776 do {
777 struct page *page;
778 unsigned long offset; /* Offset into pagecache page */
779 unsigned long bytes; /* Bytes to write to page */
780 size_t copied; /* Bytes copied from user */
781
782 offset = offset_in_page(pos);
783 bytes = min_t(unsigned long, PAGE_SIZE - offset,
784 iov_iter_count(i));
785again:
786 if (bytes > length)
787 bytes = length;
788
789 /*
790 * Bring in the user page that we will copy from _first_.
791 * Otherwise there's a nasty deadlock on copying from the
792 * same page as we're writing to, without it being marked
793 * up-to-date.
794 *
795 * Not only is this an optimisation, but it is also required
796 * to check that the address is actually valid, when atomic
797 * usercopies are used, below.
798 */
799 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
800 status = -EFAULT;
801 break;
802 }
803
804 status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap,
805 srcmap);
806 if (unlikely(status))
807 break;
808
809 if (mapping_writably_mapped(inode->i_mapping))
810 flush_dcache_page(page);
811
812 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
813
814 flush_dcache_page(page);
815
816 status = iomap_write_end(inode, pos, bytes, copied, page, iomap,
817 srcmap);
818 if (unlikely(status < 0))
819 break;
820 copied = status;
821
822 cond_resched();
823
824 iov_iter_advance(i, copied);
825 if (unlikely(copied == 0)) {
826 /*
827 * If we were unable to copy any data at all, we must
828 * fall back to a single segment length write.
829 *
830 * If we didn't fallback here, we could livelock
831 * because not all segments in the iov can be copied at
832 * once without a pagefault.
833 */
834 bytes = min_t(unsigned long, PAGE_SIZE - offset,
835 iov_iter_single_seg_count(i));
836 goto again;
837 }
838 pos += copied;
839 written += copied;
840 length -= copied;
841
842 balance_dirty_pages_ratelimited(inode->i_mapping);
843 } while (iov_iter_count(i) && length);
844
845 return written ? written : status;
846}
847
848ssize_t
849iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
850 const struct iomap_ops *ops)
851{
852 struct inode *inode = iocb->ki_filp->f_mapping->host;
853 loff_t pos = iocb->ki_pos, ret = 0, written = 0;
854
855 while (iov_iter_count(iter)) {
856 ret = iomap_apply(inode, pos, iov_iter_count(iter),
857 IOMAP_WRITE, ops, iter, iomap_write_actor);
858 if (ret <= 0)
859 break;
860 pos += ret;
861 written += ret;
862 }
863
864 return written ? written : ret;
865}
866EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
867
868static loff_t
869iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
870 struct iomap *iomap, struct iomap *srcmap)
871{
872 long status = 0;
873 loff_t written = 0;
874
875 /* don't bother with blocks that are not shared to start with */
876 if (!(iomap->flags & IOMAP_F_SHARED))
877 return length;
878 /* don't bother with holes or unwritten extents */
879 if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
880 return length;
881
882 do {
883 unsigned long offset = offset_in_page(pos);
884 unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
885 struct page *page;
886
887 status = iomap_write_begin(inode, pos, bytes,
888 IOMAP_WRITE_F_UNSHARE, &page, iomap, srcmap);
889 if (unlikely(status))
890 return status;
891
892 status = iomap_write_end(inode, pos, bytes, bytes, page, iomap,
893 srcmap);
894 if (unlikely(status <= 0)) {
895 if (WARN_ON_ONCE(status == 0))
896 return -EIO;
897 return status;
898 }
899
900 cond_resched();
901
902 pos += status;
903 written += status;
904 length -= status;
905
906 balance_dirty_pages_ratelimited(inode->i_mapping);
907 } while (length);
908
909 return written;
910}
911
912int
913iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
914 const struct iomap_ops *ops)
915{
916 loff_t ret;
917
918 while (len) {
919 ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
920 iomap_unshare_actor);
921 if (ret <= 0)
922 return ret;
923 pos += ret;
924 len -= ret;
925 }
926
927 return 0;
928}
929EXPORT_SYMBOL_GPL(iomap_file_unshare);
930
931static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
932 unsigned bytes, struct iomap *iomap, struct iomap *srcmap)
933{
934 struct page *page;
935 int status;
936
937 status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap);
938 if (status)
939 return status;
940
941 zero_user(page, offset, bytes);
942 mark_page_accessed(page);
943
944 return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap);
945}
946
947static loff_t
948iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
949 void *data, struct iomap *iomap, struct iomap *srcmap)
950{
951 bool *did_zero = data;
952 loff_t written = 0;
953 int status;
954
955 /* already zeroed? we're done. */
956 if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
957 return count;
958
959 do {
960 unsigned offset, bytes;
961
962 offset = offset_in_page(pos);
963 bytes = min_t(loff_t, PAGE_SIZE - offset, count);
964
965 if (IS_DAX(inode))
966 status = dax_iomap_zero(pos, offset, bytes, iomap);
967 else
968 status = iomap_zero(inode, pos, offset, bytes, iomap,
969 srcmap);
970 if (status < 0)
971 return status;
972
973 pos += bytes;
974 count -= bytes;
975 written += bytes;
976 if (did_zero)
977 *did_zero = true;
978 } while (count > 0);
979
980 return written;
981}
982
983int
984iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
985 const struct iomap_ops *ops)
986{
987 loff_t ret;
988
989 while (len > 0) {
990 ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
991 ops, did_zero, iomap_zero_range_actor);
992 if (ret <= 0)
993 return ret;
994
995 pos += ret;
996 len -= ret;
997 }
998
999 return 0;
1000}
1001EXPORT_SYMBOL_GPL(iomap_zero_range);
1002
1003int
1004iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
1005 const struct iomap_ops *ops)
1006{
1007 unsigned int blocksize = i_blocksize(inode);
1008 unsigned int off = pos & (blocksize - 1);
1009
1010 /* Block boundary? Nothing to do */
1011 if (!off)
1012 return 0;
1013 return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
1014}
1015EXPORT_SYMBOL_GPL(iomap_truncate_page);
1016
1017static loff_t
1018iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
1019 void *data, struct iomap *iomap, struct iomap *srcmap)
1020{
1021 struct page *page = data;
1022 int ret;
1023
1024 if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
1025 ret = __block_write_begin_int(page, pos, length, NULL, iomap);
1026 if (ret)
1027 return ret;
1028 block_commit_write(page, 0, length);
1029 } else {
1030 WARN_ON_ONCE(!PageUptodate(page));
1031 iomap_page_create(inode, page);
1032 set_page_dirty(page);
1033 }
1034
1035 return length;
1036}
1037
1038vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
1039{
1040 struct page *page = vmf->page;
1041 struct inode *inode = file_inode(vmf->vma->vm_file);
1042 unsigned long length;
1043 loff_t offset;
1044 ssize_t ret;
1045
1046 lock_page(page);
1047 ret = page_mkwrite_check_truncate(page, inode);
1048 if (ret < 0)
1049 goto out_unlock;
1050 length = ret;
1051
1052 offset = page_offset(page);
1053 while (length > 0) {
1054 ret = iomap_apply(inode, offset, length,
1055 IOMAP_WRITE | IOMAP_FAULT, ops, page,
1056 iomap_page_mkwrite_actor);
1057 if (unlikely(ret <= 0))
1058 goto out_unlock;
1059 offset += ret;
1060 length -= ret;
1061 }
1062
1063 wait_for_stable_page(page);
1064 return VM_FAULT_LOCKED;
1065out_unlock:
1066 unlock_page(page);
1067 return block_page_mkwrite_return(ret);
1068}
1069EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
1070
1071static void
1072iomap_finish_page_writeback(struct inode *inode, struct page *page,
1073 int error)
1074{
1075 struct iomap_page *iop = to_iomap_page(page);
1076
1077 if (error) {
1078 SetPageError(page);
1079 mapping_set_error(inode->i_mapping, -EIO);
1080 }
1081
1082 WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE && !iop);
1083 WARN_ON_ONCE(iop && atomic_read(&iop->write_count) <= 0);
1084
1085 if (!iop || atomic_dec_and_test(&iop->write_count))
1086 end_page_writeback(page);
1087}
1088
1089/*
1090 * We're now finished for good with this ioend structure. Update the page
1091 * state, release holds on bios, and finally free up memory. Do not use the
1092 * ioend after this.
1093 */
1094static void
1095iomap_finish_ioend(struct iomap_ioend *ioend, int error)
1096{
1097 struct inode *inode = ioend->io_inode;
1098 struct bio *bio = &ioend->io_inline_bio;
1099 struct bio *last = ioend->io_bio, *next;
1100 u64 start = bio->bi_iter.bi_sector;
1101 loff_t offset = ioend->io_offset;
1102 bool quiet = bio_flagged(bio, BIO_QUIET);
1103
1104 for (bio = &ioend->io_inline_bio; bio; bio = next) {
1105 struct bio_vec *bv;
1106 struct bvec_iter_all iter_all;
1107
1108 /*
1109 * For the last bio, bi_private points to the ioend, so we
1110 * need to explicitly end the iteration here.
1111 */
1112 if (bio == last)
1113 next = NULL;
1114 else
1115 next = bio->bi_private;
1116
1117 /* walk each page on bio, ending page IO on them */
1118 bio_for_each_segment_all(bv, bio, iter_all)
1119 iomap_finish_page_writeback(inode, bv->bv_page, error);
1120 bio_put(bio);
1121 }
1122 /* The ioend has been freed by bio_put() */
1123
1124 if (unlikely(error && !quiet)) {
1125 printk_ratelimited(KERN_ERR
1126"%s: writeback error on inode %lu, offset %lld, sector %llu",
1127 inode->i_sb->s_id, inode->i_ino, offset, start);
1128 }
1129}
1130
1131void
1132iomap_finish_ioends(struct iomap_ioend *ioend, int error)
1133{
1134 struct list_head tmp;
1135
1136 list_replace_init(&ioend->io_list, &tmp);
1137 iomap_finish_ioend(ioend, error);
1138
1139 while (!list_empty(&tmp)) {
1140 ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
1141 list_del_init(&ioend->io_list);
1142 iomap_finish_ioend(ioend, error);
1143 }
1144}
1145EXPORT_SYMBOL_GPL(iomap_finish_ioends);
1146
1147/*
1148 * We can merge two adjacent ioends if they have the same set of work to do.
1149 */
1150static bool
1151iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
1152{
1153 if (ioend->io_bio->bi_status != next->io_bio->bi_status)
1154 return false;
1155 if ((ioend->io_flags & IOMAP_F_SHARED) ^
1156 (next->io_flags & IOMAP_F_SHARED))
1157 return false;
1158 if ((ioend->io_type == IOMAP_UNWRITTEN) ^
1159 (next->io_type == IOMAP_UNWRITTEN))
1160 return false;
1161 if (ioend->io_offset + ioend->io_size != next->io_offset)
1162 return false;
1163 return true;
1164}
1165
1166void
1167iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends,
1168 void (*merge_private)(struct iomap_ioend *ioend,
1169 struct iomap_ioend *next))
1170{
1171 struct iomap_ioend *next;
1172
1173 INIT_LIST_HEAD(&ioend->io_list);
1174
1175 while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend,
1176 io_list))) {
1177 if (!iomap_ioend_can_merge(ioend, next))
1178 break;
1179 list_move_tail(&next->io_list, &ioend->io_list);
1180 ioend->io_size += next->io_size;
1181 if (next->io_private && merge_private)
1182 merge_private(ioend, next);
1183 }
1184}
1185EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
1186
1187static int
1188iomap_ioend_compare(void *priv, struct list_head *a, struct list_head *b)
1189{
1190 struct iomap_ioend *ia = container_of(a, struct iomap_ioend, io_list);
1191 struct iomap_ioend *ib = container_of(b, struct iomap_ioend, io_list);
1192
1193 if (ia->io_offset < ib->io_offset)
1194 return -1;
1195 if (ia->io_offset > ib->io_offset)
1196 return 1;
1197 return 0;
1198}
1199
1200void
1201iomap_sort_ioends(struct list_head *ioend_list)
1202{
1203 list_sort(NULL, ioend_list, iomap_ioend_compare);
1204}
1205EXPORT_SYMBOL_GPL(iomap_sort_ioends);
1206
1207static void iomap_writepage_end_bio(struct bio *bio)
1208{
1209 struct iomap_ioend *ioend = bio->bi_private;
1210
1211 iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status));
1212}
1213
1214/*
1215 * Submit the final bio for an ioend.
1216 *
1217 * If @error is non-zero, it means that we have a situation where some part of
1218 * the submission process has failed after we have marked paged for writeback
1219 * and unlocked them. In this situation, we need to fail the bio instead of
1220 * submitting it. This typically only happens on a filesystem shutdown.
1221 */
1222static int
1223iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend,
1224 int error)
1225{
1226 ioend->io_bio->bi_private = ioend;
1227 ioend->io_bio->bi_end_io = iomap_writepage_end_bio;
1228
1229 if (wpc->ops->prepare_ioend)
1230 error = wpc->ops->prepare_ioend(ioend, error);
1231 if (error) {
1232 /*
1233 * If we are failing the IO now, just mark the ioend with an
1234 * error and finish it. This will run IO completion immediately
1235 * as there is only one reference to the ioend at this point in
1236 * time.
1237 */
1238 ioend->io_bio->bi_status = errno_to_blk_status(error);
1239 bio_endio(ioend->io_bio);
1240 return error;
1241 }
1242
1243 submit_bio(ioend->io_bio);
1244 return 0;
1245}
1246
1247static struct iomap_ioend *
1248iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
1249 loff_t offset, sector_t sector, struct writeback_control *wbc)
1250{
1251 struct iomap_ioend *ioend;
1252 struct bio *bio;
1253
1254 bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &iomap_ioend_bioset);
1255 bio_set_dev(bio, wpc->iomap.bdev);
1256 bio->bi_iter.bi_sector = sector;
1257 bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
1258 bio->bi_write_hint = inode->i_write_hint;
1259 wbc_init_bio(wbc, bio);
1260
1261 ioend = container_of(bio, struct iomap_ioend, io_inline_bio);
1262 INIT_LIST_HEAD(&ioend->io_list);
1263 ioend->io_type = wpc->iomap.type;
1264 ioend->io_flags = wpc->iomap.flags;
1265 ioend->io_inode = inode;
1266 ioend->io_size = 0;
1267 ioend->io_offset = offset;
1268 ioend->io_private = NULL;
1269 ioend->io_bio = bio;
1270 return ioend;
1271}
1272
1273/*
1274 * Allocate a new bio, and chain the old bio to the new one.
1275 *
1276 * Note that we have to do perform the chaining in this unintuitive order
1277 * so that the bi_private linkage is set up in the right direction for the
1278 * traversal in iomap_finish_ioend().
1279 */
1280static struct bio *
1281iomap_chain_bio(struct bio *prev)
1282{
1283 struct bio *new;
1284
1285 new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);
1286 bio_copy_dev(new, prev);/* also copies over blkcg information */
1287 new->bi_iter.bi_sector = bio_end_sector(prev);
1288 new->bi_opf = prev->bi_opf;
1289 new->bi_write_hint = prev->bi_write_hint;
1290
1291 bio_chain(prev, new);
1292 bio_get(prev); /* for iomap_finish_ioend */
1293 submit_bio(prev);
1294 return new;
1295}
1296
1297static bool
1298iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t offset,
1299 sector_t sector)
1300{
1301 if ((wpc->iomap.flags & IOMAP_F_SHARED) !=
1302 (wpc->ioend->io_flags & IOMAP_F_SHARED))
1303 return false;
1304 if (wpc->iomap.type != wpc->ioend->io_type)
1305 return false;
1306 if (offset != wpc->ioend->io_offset + wpc->ioend->io_size)
1307 return false;
1308 if (sector != bio_end_sector(wpc->ioend->io_bio))
1309 return false;
1310 return true;
1311}
1312
1313/*
1314 * Test to see if we have an existing ioend structure that we could append to
1315 * first, otherwise finish off the current ioend and start another.
1316 */
1317static void
1318iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,
1319 struct iomap_page *iop, struct iomap_writepage_ctx *wpc,
1320 struct writeback_control *wbc, struct list_head *iolist)
1321{
1322 sector_t sector = iomap_sector(&wpc->iomap, offset);
1323 unsigned len = i_blocksize(inode);
1324 unsigned poff = offset & (PAGE_SIZE - 1);
1325 bool merged, same_page = false;
1326
1327 if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, offset, sector)) {
1328 if (wpc->ioend)
1329 list_add(&wpc->ioend->io_list, iolist);
1330 wpc->ioend = iomap_alloc_ioend(inode, wpc, offset, sector, wbc);
1331 }
1332
1333 merged = __bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
1334 &same_page);
1335 if (iop && !same_page)
1336 atomic_inc(&iop->write_count);
1337
1338 if (!merged) {
1339 if (bio_full(wpc->ioend->io_bio, len)) {
1340 wpc->ioend->io_bio =
1341 iomap_chain_bio(wpc->ioend->io_bio);
1342 }
1343 bio_add_page(wpc->ioend->io_bio, page, len, poff);
1344 }
1345
1346 wpc->ioend->io_size += len;
1347 wbc_account_cgroup_owner(wbc, page, len);
1348}
1349
1350/*
1351 * We implement an immediate ioend submission policy here to avoid needing to
1352 * chain multiple ioends and hence nest mempool allocations which can violate
1353 * forward progress guarantees we need to provide. The current ioend we are
1354 * adding blocks to is cached on the writepage context, and if the new block
1355 * does not append to the cached ioend it will create a new ioend and cache that
1356 * instead.
1357 *
1358 * If a new ioend is created and cached, the old ioend is returned and queued
1359 * locally for submission once the entire page is processed or an error has been
1360 * detected. While ioends are submitted immediately after they are completed,
1361 * batching optimisations are provided by higher level block plugging.
1362 *
1363 * At the end of a writeback pass, there will be a cached ioend remaining on the
1364 * writepage context that the caller will need to submit.
1365 */
1366static int
1367iomap_writepage_map(struct iomap_writepage_ctx *wpc,
1368 struct writeback_control *wbc, struct inode *inode,
1369 struct page *page, u64 end_offset)
1370{
1371 struct iomap_page *iop = to_iomap_page(page);
1372 struct iomap_ioend *ioend, *next;
1373 unsigned len = i_blocksize(inode);
1374 u64 file_offset; /* file offset of page */
1375 int error = 0, count = 0, i;
1376 LIST_HEAD(submit_list);
1377
1378 WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE && !iop);
1379 WARN_ON_ONCE(iop && atomic_read(&iop->write_count) != 0);
1380
1381 /*
1382 * Walk through the page to find areas to write back. If we run off the
1383 * end of the current map or find the current map invalid, grab a new
1384 * one.
1385 */
1386 for (i = 0, file_offset = page_offset(page);
1387 i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
1388 i++, file_offset += len) {
1389 if (iop && !test_bit(i, iop->uptodate))
1390 continue;
1391
1392 error = wpc->ops->map_blocks(wpc, inode, file_offset);
1393 if (error)
1394 break;
1395 if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE))
1396 continue;
1397 if (wpc->iomap.type == IOMAP_HOLE)
1398 continue;
1399 iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
1400 &submit_list);
1401 count++;
1402 }
1403
1404 WARN_ON_ONCE(!wpc->ioend && !list_empty(&submit_list));
1405 WARN_ON_ONCE(!PageLocked(page));
1406 WARN_ON_ONCE(PageWriteback(page));
1407
1408 /*
1409 * We cannot cancel the ioend directly here on error. We may have
1410 * already set other pages under writeback and hence we have to run I/O
1411 * completion to mark the error state of the pages under writeback
1412 * appropriately.
1413 */
1414 if (unlikely(error)) {
1415 if (!count) {
1416 /*
1417 * If the current page hasn't been added to ioend, it
1418 * won't be affected by I/O completions and we must
1419 * discard and unlock it right here.
1420 */
1421 if (wpc->ops->discard_page)
1422 wpc->ops->discard_page(page);
1423 ClearPageUptodate(page);
1424 unlock_page(page);
1425 goto done;
1426 }
1427
1428 /*
1429 * If the page was not fully cleaned, we need to ensure that the
1430 * higher layers come back to it correctly. That means we need
1431 * to keep the page dirty, and for WB_SYNC_ALL writeback we need
1432 * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed
1433 * so another attempt to write this page in this writeback sweep
1434 * will be made.
1435 */
1436 set_page_writeback_keepwrite(page);
1437 } else {
1438 clear_page_dirty_for_io(page);
1439 set_page_writeback(page);
1440 }
1441
1442 unlock_page(page);
1443
1444 /*
1445 * Preserve the original error if there was one, otherwise catch
1446 * submission errors here and propagate into subsequent ioend
1447 * submissions.
1448 */
1449 list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
1450 int error2;
1451
1452 list_del_init(&ioend->io_list);
1453 error2 = iomap_submit_ioend(wpc, ioend, error);
1454 if (error2 && !error)
1455 error = error2;
1456 }
1457
1458 /*
1459 * We can end up here with no error and nothing to write only if we race
1460 * with a partial page truncate on a sub-page block sized filesystem.
1461 */
1462 if (!count)
1463 end_page_writeback(page);
1464done:
1465 mapping_set_error(page->mapping, error);
1466 return error;
1467}
1468
1469/*
1470 * Write out a dirty page.
1471 *
1472 * For delalloc space on the page we need to allocate space and flush it.
1473 * For unwritten space on the page we need to start the conversion to
1474 * regular allocated space.
1475 */
1476static int
1477iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
1478{
1479 struct iomap_writepage_ctx *wpc = data;
1480 struct inode *inode = page->mapping->host;
1481 pgoff_t end_index;
1482 u64 end_offset;
1483 loff_t offset;
1484
1485 trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE);
1486
1487 /*
1488 * Refuse to write the page out if we are called from reclaim context.
1489 *
1490 * This avoids stack overflows when called from deeply used stacks in
1491 * random callers for direct reclaim or memcg reclaim. We explicitly
1492 * allow reclaim from kswapd as the stack usage there is relatively low.
1493 *
1494 * This should never happen except in the case of a VM regression so
1495 * warn about it.
1496 */
1497 if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
1498 PF_MEMALLOC))
1499 goto redirty;
1500
1501 /*
1502 * Given that we do not allow direct reclaim to call us, we should
1503 * never be called in a recursive filesystem reclaim context.
1504 */
1505 if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
1506 goto redirty;
1507
1508 /*
1509 * Is this page beyond the end of the file?
1510 *
1511 * The page index is less than the end_index, adjust the end_offset
1512 * to the highest offset that this page should represent.
1513 * -----------------------------------------------------
1514 * | file mapping | <EOF> |
1515 * -----------------------------------------------------
1516 * | Page ... | Page N-2 | Page N-1 | Page N | |
1517 * ^--------------------------------^----------|--------
1518 * | desired writeback range | see else |
1519 * ---------------------------------^------------------|
1520 */
1521 offset = i_size_read(inode);
1522 end_index = offset >> PAGE_SHIFT;
1523 if (page->index < end_index)
1524 end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT;
1525 else {
1526 /*
1527 * Check whether the page to write out is beyond or straddles
1528 * i_size or not.
1529 * -------------------------------------------------------
1530 * | file mapping | <EOF> |
1531 * -------------------------------------------------------
1532 * | Page ... | Page N-2 | Page N-1 | Page N | Beyond |
1533 * ^--------------------------------^-----------|---------
1534 * | | Straddles |
1535 * ---------------------------------^-----------|--------|
1536 */
1537 unsigned offset_into_page = offset & (PAGE_SIZE - 1);
1538
1539 /*
1540 * Skip the page if it is fully outside i_size, e.g. due to a
1541 * truncate operation that is in progress. We must redirty the
1542 * page so that reclaim stops reclaiming it. Otherwise
1543 * iomap_vm_releasepage() is called on it and gets confused.
1544 *
1545 * Note that the end_index is unsigned long, it would overflow
1546 * if the given offset is greater than 16TB on 32-bit system
1547 * and if we do check the page is fully outside i_size or not
1548 * via "if (page->index >= end_index + 1)" as "end_index + 1"
1549 * will be evaluated to 0. Hence this page will be redirtied
1550 * and be written out repeatedly which would result in an
1551 * infinite loop, the user program that perform this operation
1552 * will hang. Instead, we can verify this situation by checking
1553 * if the page to write is totally beyond the i_size or if it's
1554 * offset is just equal to the EOF.
1555 */
1556 if (page->index > end_index ||
1557 (page->index == end_index && offset_into_page == 0))
1558 goto redirty;
1559
1560 /*
1561 * The page straddles i_size. It must be zeroed out on each
1562 * and every writepage invocation because it may be mmapped.
1563 * "A file is mapped in multiples of the page size. For a file
1564 * that is not a multiple of the page size, the remaining
1565 * memory is zeroed when mapped, and writes to that region are
1566 * not written out to the file."
1567 */
1568 zero_user_segment(page, offset_into_page, PAGE_SIZE);
1569
1570 /* Adjust the end_offset to the end of file */
1571 end_offset = offset;
1572 }
1573
1574 return iomap_writepage_map(wpc, wbc, inode, page, end_offset);
1575
1576redirty:
1577 redirty_page_for_writepage(wbc, page);
1578 unlock_page(page);
1579 return 0;
1580}
1581
1582int
1583iomap_writepage(struct page *page, struct writeback_control *wbc,
1584 struct iomap_writepage_ctx *wpc,
1585 const struct iomap_writeback_ops *ops)
1586{
1587 int ret;
1588
1589 wpc->ops = ops;
1590 ret = iomap_do_writepage(page, wbc, wpc);
1591 if (!wpc->ioend)
1592 return ret;
1593 return iomap_submit_ioend(wpc, wpc->ioend, ret);
1594}
1595EXPORT_SYMBOL_GPL(iomap_writepage);
1596
1597int
1598iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
1599 struct iomap_writepage_ctx *wpc,
1600 const struct iomap_writeback_ops *ops)
1601{
1602 int ret;
1603
1604 wpc->ops = ops;
1605 ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc);
1606 if (!wpc->ioend)
1607 return ret;
1608 return iomap_submit_ioend(wpc, wpc->ioend, ret);
1609}
1610EXPORT_SYMBOL_GPL(iomap_writepages);
1611
1612static int __init iomap_init(void)
1613{
1614 return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
1615 offsetof(struct iomap_ioend, io_inline_bio),
1616 BIOSET_NEED_BVECS);
1617}
1618fs_initcall(iomap_init);