mm: migrate: drop unused argument of migrate_page_move_mapping()
[sfrench/cifs-2.6.git] / fs / iomap.c
1 /*
2  * Copyright (C) 2010 Red Hat, Inc.
3  * Copyright (c) 2016-2018 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/migrate.h>
21 #include <linux/mm.h>
22 #include <linux/mm_inline.h>
23 #include <linux/swap.h>
24 #include <linux/pagemap.h>
25 #include <linux/pagevec.h>
26 #include <linux/file.h>
27 #include <linux/uio.h>
28 #include <linux/backing-dev.h>
29 #include <linux/buffer_head.h>
30 #include <linux/task_io_accounting_ops.h>
31 #include <linux/dax.h>
32 #include <linux/sched/signal.h>
33
34 #include "internal.h"
35
36 /*
37  * Execute a iomap write on a segment of the mapping that spans a
38  * contiguous range of pages that have identical block mapping state.
39  *
40  * This avoids the need to map pages individually, do individual allocations
41  * for each page and most importantly avoid the need for filesystem specific
42  * locking per page. Instead, all the operations are amortised over the entire
43  * range of pages. It is assumed that the filesystems will lock whatever
44  * resources they require in the iomap_begin call, and release them in the
45  * iomap_end call.
46  */
47 loff_t
48 iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
49                 const struct iomap_ops *ops, void *data, iomap_actor_t actor)
50 {
51         struct iomap iomap = { 0 };
52         loff_t written = 0, ret;
53
54         /*
55          * Need to map a range from start position for length bytes. This can
56          * span multiple pages - it is only guaranteed to return a range of a
57          * single type of pages (e.g. all into a hole, all mapped or all
58          * unwritten). Failure at this point has nothing to undo.
59          *
60          * If allocation is required for this range, reserve the space now so
61          * that the allocation is guaranteed to succeed later on. Once we copy
62          * the data into the page cache pages, then we cannot fail otherwise we
63          * expose transient stale data. If the reserve fails, we can safely
64          * back out at this point as there is nothing to undo.
65          */
66         ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
67         if (ret)
68                 return ret;
69         if (WARN_ON(iomap.offset > pos))
70                 return -EIO;
71         if (WARN_ON(iomap.length == 0))
72                 return -EIO;
73
74         /*
75          * Cut down the length to the one actually provided by the filesystem,
76          * as it might not be able to give us the whole size that we requested.
77          */
78         if (iomap.offset + iomap.length < pos + length)
79                 length = iomap.offset + iomap.length - pos;
80
81         /*
82          * Now that we have guaranteed that the space allocation will succeed.
83          * we can do the copy-in page by page without having to worry about
84          * failures exposing transient data.
85          */
86         written = actor(inode, pos, length, data, &iomap);
87
88         /*
89          * Now the data has been copied, commit the range we've copied.  This
90          * should not fail unless the filesystem has had a fatal error.
91          */
92         if (ops->iomap_end) {
93                 ret = ops->iomap_end(inode, pos, length,
94                                      written > 0 ? written : 0,
95                                      flags, &iomap);
96         }
97
98         return written ? written : ret;
99 }
100
101 static sector_t
102 iomap_sector(struct iomap *iomap, loff_t pos)
103 {
104         return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
105 }
106
107 static struct iomap_page *
108 iomap_page_create(struct inode *inode, struct page *page)
109 {
110         struct iomap_page *iop = to_iomap_page(page);
111
112         if (iop || i_blocksize(inode) == PAGE_SIZE)
113                 return iop;
114
115         iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
116         atomic_set(&iop->read_count, 0);
117         atomic_set(&iop->write_count, 0);
118         bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
119         set_page_private(page, (unsigned long)iop);
120         SetPagePrivate(page);
121         return iop;
122 }
123
124 static void
125 iomap_page_release(struct page *page)
126 {
127         struct iomap_page *iop = to_iomap_page(page);
128
129         if (!iop)
130                 return;
131         WARN_ON_ONCE(atomic_read(&iop->read_count));
132         WARN_ON_ONCE(atomic_read(&iop->write_count));
133         ClearPagePrivate(page);
134         set_page_private(page, 0);
135         kfree(iop);
136 }
137
138 /*
139  * Calculate the range inside the page that we actually need to read.
140  */
141 static void
142 iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
143                 loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
144 {
145         loff_t orig_pos = *pos;
146         loff_t isize = i_size_read(inode);
147         unsigned block_bits = inode->i_blkbits;
148         unsigned block_size = (1 << block_bits);
149         unsigned poff = offset_in_page(*pos);
150         unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
151         unsigned first = poff >> block_bits;
152         unsigned last = (poff + plen - 1) >> block_bits;
153
154         /*
155          * If the block size is smaller than the page size we need to check the
156          * per-block uptodate status and adjust the offset and length if needed
157          * to avoid reading in already uptodate ranges.
158          */
159         if (iop) {
160                 unsigned int i;
161
162                 /* move forward for each leading block marked uptodate */
163                 for (i = first; i <= last; i++) {
164                         if (!test_bit(i, iop->uptodate))
165                                 break;
166                         *pos += block_size;
167                         poff += block_size;
168                         plen -= block_size;
169                         first++;
170                 }
171
172                 /* truncate len if we find any trailing uptodate block(s) */
173                 for ( ; i <= last; i++) {
174                         if (test_bit(i, iop->uptodate)) {
175                                 plen -= (last - i + 1) * block_size;
176                                 last = i - 1;
177                                 break;
178                         }
179                 }
180         }
181
182         /*
183          * If the extent spans the block that contains the i_size we need to
184          * handle both halves separately so that we properly zero data in the
185          * page cache for blocks that are entirely outside of i_size.
186          */
187         if (orig_pos <= isize && orig_pos + length > isize) {
188                 unsigned end = offset_in_page(isize - 1) >> block_bits;
189
190                 if (first <= end && last > end)
191                         plen -= (last - end) * block_size;
192         }
193
194         *offp = poff;
195         *lenp = plen;
196 }
197
198 static void
199 iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
200 {
201         struct iomap_page *iop = to_iomap_page(page);
202         struct inode *inode = page->mapping->host;
203         unsigned first = off >> inode->i_blkbits;
204         unsigned last = (off + len - 1) >> inode->i_blkbits;
205         unsigned int i;
206         bool uptodate = true;
207
208         if (iop) {
209                 for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
210                         if (i >= first && i <= last)
211                                 set_bit(i, iop->uptodate);
212                         else if (!test_bit(i, iop->uptodate))
213                                 uptodate = false;
214                 }
215         }
216
217         if (uptodate && !PageError(page))
218                 SetPageUptodate(page);
219 }
220
221 static void
222 iomap_read_finish(struct iomap_page *iop, struct page *page)
223 {
224         if (!iop || atomic_dec_and_test(&iop->read_count))
225                 unlock_page(page);
226 }
227
228 static void
229 iomap_read_page_end_io(struct bio_vec *bvec, int error)
230 {
231         struct page *page = bvec->bv_page;
232         struct iomap_page *iop = to_iomap_page(page);
233
234         if (unlikely(error)) {
235                 ClearPageUptodate(page);
236                 SetPageError(page);
237         } else {
238                 iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
239         }
240
241         iomap_read_finish(iop, page);
242 }
243
244 static void
245 iomap_read_inline_data(struct inode *inode, struct page *page,
246                 struct iomap *iomap)
247 {
248         size_t size = i_size_read(inode);
249         void *addr;
250
251         if (PageUptodate(page))
252                 return;
253
254         BUG_ON(page->index);
255         BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
256
257         addr = kmap_atomic(page);
258         memcpy(addr, iomap->inline_data, size);
259         memset(addr + size, 0, PAGE_SIZE - size);
260         kunmap_atomic(addr);
261         SetPageUptodate(page);
262 }
263
264 static void
265 iomap_read_end_io(struct bio *bio)
266 {
267         int error = blk_status_to_errno(bio->bi_status);
268         struct bio_vec *bvec;
269         int i;
270
271         bio_for_each_segment_all(bvec, bio, i)
272                 iomap_read_page_end_io(bvec, error);
273         bio_put(bio);
274 }
275
276 struct iomap_readpage_ctx {
277         struct page             *cur_page;
278         bool                    cur_page_in_bio;
279         bool                    is_readahead;
280         struct bio              *bio;
281         struct list_head        *pages;
282 };
283
284 static loff_t
285 iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
286                 struct iomap *iomap)
287 {
288         struct iomap_readpage_ctx *ctx = data;
289         struct page *page = ctx->cur_page;
290         struct iomap_page *iop = iomap_page_create(inode, page);
291         bool is_contig = false;
292         loff_t orig_pos = pos;
293         unsigned poff, plen;
294         sector_t sector;
295
296         if (iomap->type == IOMAP_INLINE) {
297                 WARN_ON_ONCE(pos);
298                 iomap_read_inline_data(inode, page, iomap);
299                 return PAGE_SIZE;
300         }
301
302         /* zero post-eof blocks as the page may be mapped */
303         iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
304         if (plen == 0)
305                 goto done;
306
307         if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) {
308                 zero_user(page, poff, plen);
309                 iomap_set_range_uptodate(page, poff, plen);
310                 goto done;
311         }
312
313         ctx->cur_page_in_bio = true;
314
315         /*
316          * Try to merge into a previous segment if we can.
317          */
318         sector = iomap_sector(iomap, pos);
319         if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
320                 if (__bio_try_merge_page(ctx->bio, page, plen, poff))
321                         goto done;
322                 is_contig = true;
323         }
324
325         /*
326          * If we start a new segment we need to increase the read count, and we
327          * need to do so before submitting any previous full bio to make sure
328          * that we don't prematurely unlock the page.
329          */
330         if (iop)
331                 atomic_inc(&iop->read_count);
332
333         if (!ctx->bio || !is_contig || bio_full(ctx->bio)) {
334                 gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
335                 int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
336
337                 if (ctx->bio)
338                         submit_bio(ctx->bio);
339
340                 if (ctx->is_readahead) /* same as readahead_gfp_mask */
341                         gfp |= __GFP_NORETRY | __GFP_NOWARN;
342                 ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
343                 ctx->bio->bi_opf = REQ_OP_READ;
344                 if (ctx->is_readahead)
345                         ctx->bio->bi_opf |= REQ_RAHEAD;
346                 ctx->bio->bi_iter.bi_sector = sector;
347                 bio_set_dev(ctx->bio, iomap->bdev);
348                 ctx->bio->bi_end_io = iomap_read_end_io;
349         }
350
351         __bio_add_page(ctx->bio, page, plen, poff);
352 done:
353         /*
354          * Move the caller beyond our range so that it keeps making progress.
355          * For that we have to include any leading non-uptodate ranges, but
356          * we can skip trailing ones as they will be handled in the next
357          * iteration.
358          */
359         return pos - orig_pos + plen;
360 }
361
362 int
363 iomap_readpage(struct page *page, const struct iomap_ops *ops)
364 {
365         struct iomap_readpage_ctx ctx = { .cur_page = page };
366         struct inode *inode = page->mapping->host;
367         unsigned poff;
368         loff_t ret;
369
370         for (poff = 0; poff < PAGE_SIZE; poff += ret) {
371                 ret = iomap_apply(inode, page_offset(page) + poff,
372                                 PAGE_SIZE - poff, 0, ops, &ctx,
373                                 iomap_readpage_actor);
374                 if (ret <= 0) {
375                         WARN_ON_ONCE(ret == 0);
376                         SetPageError(page);
377                         break;
378                 }
379         }
380
381         if (ctx.bio) {
382                 submit_bio(ctx.bio);
383                 WARN_ON_ONCE(!ctx.cur_page_in_bio);
384         } else {
385                 WARN_ON_ONCE(ctx.cur_page_in_bio);
386                 unlock_page(page);
387         }
388
389         /*
390          * Just like mpage_readpages and block_read_full_page we always
391          * return 0 and just mark the page as PageError on errors.  This
392          * should be cleaned up all through the stack eventually.
393          */
394         return 0;
395 }
396 EXPORT_SYMBOL_GPL(iomap_readpage);
397
398 static struct page *
399 iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
400                 loff_t length, loff_t *done)
401 {
402         while (!list_empty(pages)) {
403                 struct page *page = lru_to_page(pages);
404
405                 if (page_offset(page) >= (u64)pos + length)
406                         break;
407
408                 list_del(&page->lru);
409                 if (!add_to_page_cache_lru(page, inode->i_mapping, page->index,
410                                 GFP_NOFS))
411                         return page;
412
413                 /*
414                  * If we already have a page in the page cache at index we are
415                  * done.  Upper layers don't care if it is uptodate after the
416                  * readpages call itself as every page gets checked again once
417                  * actually needed.
418                  */
419                 *done += PAGE_SIZE;
420                 put_page(page);
421         }
422
423         return NULL;
424 }
425
426 static loff_t
427 iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
428                 void *data, struct iomap *iomap)
429 {
430         struct iomap_readpage_ctx *ctx = data;
431         loff_t done, ret;
432
433         for (done = 0; done < length; done += ret) {
434                 if (ctx->cur_page && offset_in_page(pos + done) == 0) {
435                         if (!ctx->cur_page_in_bio)
436                                 unlock_page(ctx->cur_page);
437                         put_page(ctx->cur_page);
438                         ctx->cur_page = NULL;
439                 }
440                 if (!ctx->cur_page) {
441                         ctx->cur_page = iomap_next_page(inode, ctx->pages,
442                                         pos, length, &done);
443                         if (!ctx->cur_page)
444                                 break;
445                         ctx->cur_page_in_bio = false;
446                 }
447                 ret = iomap_readpage_actor(inode, pos + done, length - done,
448                                 ctx, iomap);
449         }
450
451         return done;
452 }
453
454 int
455 iomap_readpages(struct address_space *mapping, struct list_head *pages,
456                 unsigned nr_pages, const struct iomap_ops *ops)
457 {
458         struct iomap_readpage_ctx ctx = {
459                 .pages          = pages,
460                 .is_readahead   = true,
461         };
462         loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
463         loff_t last = page_offset(list_entry(pages->next, struct page, lru));
464         loff_t length = last - pos + PAGE_SIZE, ret = 0;
465
466         while (length > 0) {
467                 ret = iomap_apply(mapping->host, pos, length, 0, ops,
468                                 &ctx, iomap_readpages_actor);
469                 if (ret <= 0) {
470                         WARN_ON_ONCE(ret == 0);
471                         goto done;
472                 }
473                 pos += ret;
474                 length -= ret;
475         }
476         ret = 0;
477 done:
478         if (ctx.bio)
479                 submit_bio(ctx.bio);
480         if (ctx.cur_page) {
481                 if (!ctx.cur_page_in_bio)
482                         unlock_page(ctx.cur_page);
483                 put_page(ctx.cur_page);
484         }
485
486         /*
487          * Check that we didn't lose a page due to the arcance calling
488          * conventions..
489          */
490         WARN_ON_ONCE(!ret && !list_empty(ctx.pages));
491         return ret;
492 }
493 EXPORT_SYMBOL_GPL(iomap_readpages);
494
495 /*
496  * iomap_is_partially_uptodate checks whether blocks within a page are
497  * uptodate or not.
498  *
499  * Returns true if all blocks which correspond to a file portion
500  * we want to read within the page are uptodate.
501  */
502 int
503 iomap_is_partially_uptodate(struct page *page, unsigned long from,
504                 unsigned long count)
505 {
506         struct iomap_page *iop = to_iomap_page(page);
507         struct inode *inode = page->mapping->host;
508         unsigned len, first, last;
509         unsigned i;
510
511         /* Limit range to one page */
512         len = min_t(unsigned, PAGE_SIZE - from, count);
513
514         /* First and last blocks in range within page */
515         first = from >> inode->i_blkbits;
516         last = (from + len - 1) >> inode->i_blkbits;
517
518         if (iop) {
519                 for (i = first; i <= last; i++)
520                         if (!test_bit(i, iop->uptodate))
521                                 return 0;
522                 return 1;
523         }
524
525         return 0;
526 }
527 EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
528
529 int
530 iomap_releasepage(struct page *page, gfp_t gfp_mask)
531 {
532         /*
533          * mm accommodates an old ext3 case where clean pages might not have had
534          * the dirty bit cleared. Thus, it can send actual dirty pages to
535          * ->releasepage() via shrink_active_list(), skip those here.
536          */
537         if (PageDirty(page) || PageWriteback(page))
538                 return 0;
539         iomap_page_release(page);
540         return 1;
541 }
542 EXPORT_SYMBOL_GPL(iomap_releasepage);
543
544 void
545 iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
546 {
547         /*
548          * If we are invalidating the entire page, clear the dirty state from it
549          * and release it to avoid unnecessary buildup of the LRU.
550          */
551         if (offset == 0 && len == PAGE_SIZE) {
552                 WARN_ON_ONCE(PageWriteback(page));
553                 cancel_dirty_page(page);
554                 iomap_page_release(page);
555         }
556 }
557 EXPORT_SYMBOL_GPL(iomap_invalidatepage);
558
559 #ifdef CONFIG_MIGRATION
560 int
561 iomap_migrate_page(struct address_space *mapping, struct page *newpage,
562                 struct page *page, enum migrate_mode mode)
563 {
564         int ret;
565
566         ret = migrate_page_move_mapping(mapping, newpage, page, mode, 0);
567         if (ret != MIGRATEPAGE_SUCCESS)
568                 return ret;
569
570         if (page_has_private(page)) {
571                 ClearPagePrivate(page);
572                 set_page_private(newpage, page_private(page));
573                 set_page_private(page, 0);
574                 SetPagePrivate(newpage);
575         }
576
577         if (mode != MIGRATE_SYNC_NO_COPY)
578                 migrate_page_copy(newpage, page);
579         else
580                 migrate_page_states(newpage, page);
581         return MIGRATEPAGE_SUCCESS;
582 }
583 EXPORT_SYMBOL_GPL(iomap_migrate_page);
584 #endif /* CONFIG_MIGRATION */
585
586 static void
587 iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
588 {
589         loff_t i_size = i_size_read(inode);
590
591         /*
592          * Only truncate newly allocated pages beyoned EOF, even if the
593          * write started inside the existing inode size.
594          */
595         if (pos + len > i_size)
596                 truncate_pagecache_range(inode, max(pos, i_size), pos + len);
597 }
598
599 static int
600 iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page,
601                 unsigned poff, unsigned plen, unsigned from, unsigned to,
602                 struct iomap *iomap)
603 {
604         struct bio_vec bvec;
605         struct bio bio;
606
607         if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) {
608                 zero_user_segments(page, poff, from, to, poff + plen);
609                 iomap_set_range_uptodate(page, poff, plen);
610                 return 0;
611         }
612
613         bio_init(&bio, &bvec, 1);
614         bio.bi_opf = REQ_OP_READ;
615         bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
616         bio_set_dev(&bio, iomap->bdev);
617         __bio_add_page(&bio, page, plen, poff);
618         return submit_bio_wait(&bio);
619 }
620
621 static int
622 __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
623                 struct page *page, struct iomap *iomap)
624 {
625         struct iomap_page *iop = iomap_page_create(inode, page);
626         loff_t block_size = i_blocksize(inode);
627         loff_t block_start = pos & ~(block_size - 1);
628         loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
629         unsigned from = offset_in_page(pos), to = from + len, poff, plen;
630         int status = 0;
631
632         if (PageUptodate(page))
633                 return 0;
634
635         do {
636                 iomap_adjust_read_range(inode, iop, &block_start,
637                                 block_end - block_start, &poff, &plen);
638                 if (plen == 0)
639                         break;
640
641                 if ((from > poff && from < poff + plen) ||
642                     (to > poff && to < poff + plen)) {
643                         status = iomap_read_page_sync(inode, block_start, page,
644                                         poff, plen, from, to, iomap);
645                         if (status)
646                                 break;
647                 }
648
649         } while ((block_start += plen) < block_end);
650
651         return status;
652 }
653
654 static int
655 iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
656                 struct page **pagep, struct iomap *iomap)
657 {
658         pgoff_t index = pos >> PAGE_SHIFT;
659         struct page *page;
660         int status = 0;
661
662         BUG_ON(pos + len > iomap->offset + iomap->length);
663
664         if (fatal_signal_pending(current))
665                 return -EINTR;
666
667         page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
668         if (!page)
669                 return -ENOMEM;
670
671         if (iomap->type == IOMAP_INLINE)
672                 iomap_read_inline_data(inode, page, iomap);
673         else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
674                 status = __block_write_begin_int(page, pos, len, NULL, iomap);
675         else
676                 status = __iomap_write_begin(inode, pos, len, page, iomap);
677         if (unlikely(status)) {
678                 unlock_page(page);
679                 put_page(page);
680                 page = NULL;
681
682                 iomap_write_failed(inode, pos, len);
683         }
684
685         *pagep = page;
686         return status;
687 }
688
689 int
690 iomap_set_page_dirty(struct page *page)
691 {
692         struct address_space *mapping = page_mapping(page);
693         int newly_dirty;
694
695         if (unlikely(!mapping))
696                 return !TestSetPageDirty(page);
697
698         /*
699          * Lock out page->mem_cgroup migration to keep PageDirty
700          * synchronized with per-memcg dirty page counters.
701          */
702         lock_page_memcg(page);
703         newly_dirty = !TestSetPageDirty(page);
704         if (newly_dirty)
705                 __set_page_dirty(page, mapping, 0);
706         unlock_page_memcg(page);
707
708         if (newly_dirty)
709                 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
710         return newly_dirty;
711 }
712 EXPORT_SYMBOL_GPL(iomap_set_page_dirty);
713
714 static int
715 __iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
716                 unsigned copied, struct page *page, struct iomap *iomap)
717 {
718         flush_dcache_page(page);
719
720         /*
721          * The blocks that were entirely written will now be uptodate, so we
722          * don't have to worry about a readpage reading them and overwriting a
723          * partial write.  However if we have encountered a short write and only
724          * partially written into a block, it will not be marked uptodate, so a
725          * readpage might come in and destroy our partial write.
726          *
727          * Do the simplest thing, and just treat any short write to a non
728          * uptodate page as a zero-length write, and force the caller to redo
729          * the whole thing.
730          */
731         if (unlikely(copied < len && !PageUptodate(page))) {
732                 copied = 0;
733         } else {
734                 iomap_set_range_uptodate(page, offset_in_page(pos), len);
735                 iomap_set_page_dirty(page);
736         }
737         return __generic_write_end(inode, pos, copied, page);
738 }
739
740 static int
741 iomap_write_end_inline(struct inode *inode, struct page *page,
742                 struct iomap *iomap, loff_t pos, unsigned copied)
743 {
744         void *addr;
745
746         WARN_ON_ONCE(!PageUptodate(page));
747         BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
748
749         addr = kmap_atomic(page);
750         memcpy(iomap->inline_data + pos, addr + pos, copied);
751         kunmap_atomic(addr);
752
753         mark_inode_dirty(inode);
754         __generic_write_end(inode, pos, copied, page);
755         return copied;
756 }
757
758 static int
759 iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
760                 unsigned copied, struct page *page, struct iomap *iomap)
761 {
762         int ret;
763
764         if (iomap->type == IOMAP_INLINE) {
765                 ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
766         } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
767                 ret = generic_write_end(NULL, inode->i_mapping, pos, len,
768                                 copied, page, NULL);
769         } else {
770                 ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
771         }
772
773         if (iomap->page_done)
774                 iomap->page_done(inode, pos, copied, page, iomap);
775
776         if (ret < len)
777                 iomap_write_failed(inode, pos, len);
778         return ret;
779 }
780
781 static loff_t
782 iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
783                 struct iomap *iomap)
784 {
785         struct iov_iter *i = data;
786         long status = 0;
787         ssize_t written = 0;
788         unsigned int flags = AOP_FLAG_NOFS;
789
790         do {
791                 struct page *page;
792                 unsigned long offset;   /* Offset into pagecache page */
793                 unsigned long bytes;    /* Bytes to write to page */
794                 size_t copied;          /* Bytes copied from user */
795
796                 offset = offset_in_page(pos);
797                 bytes = min_t(unsigned long, PAGE_SIZE - offset,
798                                                 iov_iter_count(i));
799 again:
800                 if (bytes > length)
801                         bytes = length;
802
803                 /*
804                  * Bring in the user page that we will copy from _first_.
805                  * Otherwise there's a nasty deadlock on copying from the
806                  * same page as we're writing to, without it being marked
807                  * up-to-date.
808                  *
809                  * Not only is this an optimisation, but it is also required
810                  * to check that the address is actually valid, when atomic
811                  * usercopies are used, below.
812                  */
813                 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
814                         status = -EFAULT;
815                         break;
816                 }
817
818                 status = iomap_write_begin(inode, pos, bytes, flags, &page,
819                                 iomap);
820                 if (unlikely(status))
821                         break;
822
823                 if (mapping_writably_mapped(inode->i_mapping))
824                         flush_dcache_page(page);
825
826                 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
827
828                 flush_dcache_page(page);
829
830                 status = iomap_write_end(inode, pos, bytes, copied, page,
831                                 iomap);
832                 if (unlikely(status < 0))
833                         break;
834                 copied = status;
835
836                 cond_resched();
837
838                 iov_iter_advance(i, copied);
839                 if (unlikely(copied == 0)) {
840                         /*
841                          * If we were unable to copy any data at all, we must
842                          * fall back to a single segment length write.
843                          *
844                          * If we didn't fallback here, we could livelock
845                          * because not all segments in the iov can be copied at
846                          * once without a pagefault.
847                          */
848                         bytes = min_t(unsigned long, PAGE_SIZE - offset,
849                                                 iov_iter_single_seg_count(i));
850                         goto again;
851                 }
852                 pos += copied;
853                 written += copied;
854                 length -= copied;
855
856                 balance_dirty_pages_ratelimited(inode->i_mapping);
857         } while (iov_iter_count(i) && length);
858
859         return written ? written : status;
860 }
861
862 ssize_t
863 iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
864                 const struct iomap_ops *ops)
865 {
866         struct inode *inode = iocb->ki_filp->f_mapping->host;
867         loff_t pos = iocb->ki_pos, ret = 0, written = 0;
868
869         while (iov_iter_count(iter)) {
870                 ret = iomap_apply(inode, pos, iov_iter_count(iter),
871                                 IOMAP_WRITE, ops, iter, iomap_write_actor);
872                 if (ret <= 0)
873                         break;
874                 pos += ret;
875                 written += ret;
876         }
877
878         return written ? written : ret;
879 }
880 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
881
882 static struct page *
883 __iomap_read_page(struct inode *inode, loff_t offset)
884 {
885         struct address_space *mapping = inode->i_mapping;
886         struct page *page;
887
888         page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
889         if (IS_ERR(page))
890                 return page;
891         if (!PageUptodate(page)) {
892                 put_page(page);
893                 return ERR_PTR(-EIO);
894         }
895         return page;
896 }
897
898 static loff_t
899 iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
900                 struct iomap *iomap)
901 {
902         long status = 0;
903         ssize_t written = 0;
904
905         do {
906                 struct page *page, *rpage;
907                 unsigned long offset;   /* Offset into pagecache page */
908                 unsigned long bytes;    /* Bytes to write to page */
909
910                 offset = offset_in_page(pos);
911                 bytes = min_t(loff_t, PAGE_SIZE - offset, length);
912
913                 rpage = __iomap_read_page(inode, pos);
914                 if (IS_ERR(rpage))
915                         return PTR_ERR(rpage);
916
917                 status = iomap_write_begin(inode, pos, bytes,
918                                            AOP_FLAG_NOFS, &page, iomap);
919                 put_page(rpage);
920                 if (unlikely(status))
921                         return status;
922
923                 WARN_ON_ONCE(!PageUptodate(page));
924
925                 status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
926                 if (unlikely(status <= 0)) {
927                         if (WARN_ON_ONCE(status == 0))
928                                 return -EIO;
929                         return status;
930                 }
931
932                 cond_resched();
933
934                 pos += status;
935                 written += status;
936                 length -= status;
937
938                 balance_dirty_pages_ratelimited(inode->i_mapping);
939         } while (length);
940
941         return written;
942 }
943
944 int
945 iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
946                 const struct iomap_ops *ops)
947 {
948         loff_t ret;
949
950         while (len) {
951                 ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
952                                 iomap_dirty_actor);
953                 if (ret <= 0)
954                         return ret;
955                 pos += ret;
956                 len -= ret;
957         }
958
959         return 0;
960 }
961 EXPORT_SYMBOL_GPL(iomap_file_dirty);
962
963 static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
964                 unsigned bytes, struct iomap *iomap)
965 {
966         struct page *page;
967         int status;
968
969         status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page,
970                                    iomap);
971         if (status)
972                 return status;
973
974         zero_user(page, offset, bytes);
975         mark_page_accessed(page);
976
977         return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
978 }
979
980 static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
981                 struct iomap *iomap)
982 {
983         return __dax_zero_page_range(iomap->bdev, iomap->dax_dev,
984                         iomap_sector(iomap, pos & PAGE_MASK), offset, bytes);
985 }
986
987 static loff_t
988 iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
989                 void *data, struct iomap *iomap)
990 {
991         bool *did_zero = data;
992         loff_t written = 0;
993         int status;
994
995         /* already zeroed?  we're done. */
996         if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
997                 return count;
998
999         do {
1000                 unsigned offset, bytes;
1001
1002                 offset = offset_in_page(pos);
1003                 bytes = min_t(loff_t, PAGE_SIZE - offset, count);
1004
1005                 if (IS_DAX(inode))
1006                         status = iomap_dax_zero(pos, offset, bytes, iomap);
1007                 else
1008                         status = iomap_zero(inode, pos, offset, bytes, iomap);
1009                 if (status < 0)
1010                         return status;
1011
1012                 pos += bytes;
1013                 count -= bytes;
1014                 written += bytes;
1015                 if (did_zero)
1016                         *did_zero = true;
1017         } while (count > 0);
1018
1019         return written;
1020 }
1021
1022 int
1023 iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
1024                 const struct iomap_ops *ops)
1025 {
1026         loff_t ret;
1027
1028         while (len > 0) {
1029                 ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
1030                                 ops, did_zero, iomap_zero_range_actor);
1031                 if (ret <= 0)
1032                         return ret;
1033
1034                 pos += ret;
1035                 len -= ret;
1036         }
1037
1038         return 0;
1039 }
1040 EXPORT_SYMBOL_GPL(iomap_zero_range);
1041
1042 int
1043 iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
1044                 const struct iomap_ops *ops)
1045 {
1046         unsigned int blocksize = i_blocksize(inode);
1047         unsigned int off = pos & (blocksize - 1);
1048
1049         /* Block boundary? Nothing to do */
1050         if (!off)
1051                 return 0;
1052         return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
1053 }
1054 EXPORT_SYMBOL_GPL(iomap_truncate_page);
1055
1056 static loff_t
1057 iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
1058                 void *data, struct iomap *iomap)
1059 {
1060         struct page *page = data;
1061         int ret;
1062
1063         if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
1064                 ret = __block_write_begin_int(page, pos, length, NULL, iomap);
1065                 if (ret)
1066                         return ret;
1067                 block_commit_write(page, 0, length);
1068         } else {
1069                 WARN_ON_ONCE(!PageUptodate(page));
1070                 iomap_page_create(inode, page);
1071                 set_page_dirty(page);
1072         }
1073
1074         return length;
1075 }
1076
1077 vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
1078 {
1079         struct page *page = vmf->page;
1080         struct inode *inode = file_inode(vmf->vma->vm_file);
1081         unsigned long length;
1082         loff_t offset, size;
1083         ssize_t ret;
1084
1085         lock_page(page);
1086         size = i_size_read(inode);
1087         if ((page->mapping != inode->i_mapping) ||
1088             (page_offset(page) > size)) {
1089                 /* We overload EFAULT to mean page got truncated */
1090                 ret = -EFAULT;
1091                 goto out_unlock;
1092         }
1093
1094         /* page is wholly or partially inside EOF */
1095         if (((page->index + 1) << PAGE_SHIFT) > size)
1096                 length = offset_in_page(size);
1097         else
1098                 length = PAGE_SIZE;
1099
1100         offset = page_offset(page);
1101         while (length > 0) {
1102                 ret = iomap_apply(inode, offset, length,
1103                                 IOMAP_WRITE | IOMAP_FAULT, ops, page,
1104                                 iomap_page_mkwrite_actor);
1105                 if (unlikely(ret <= 0))
1106                         goto out_unlock;
1107                 offset += ret;
1108                 length -= ret;
1109         }
1110
1111         wait_for_stable_page(page);
1112         return VM_FAULT_LOCKED;
1113 out_unlock:
1114         unlock_page(page);
1115         return block_page_mkwrite_return(ret);
1116 }
1117 EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
1118
1119 struct fiemap_ctx {
1120         struct fiemap_extent_info *fi;
1121         struct iomap prev;
1122 };
1123
1124 static int iomap_to_fiemap(struct fiemap_extent_info *fi,
1125                 struct iomap *iomap, u32 flags)
1126 {
1127         switch (iomap->type) {
1128         case IOMAP_HOLE:
1129                 /* skip holes */
1130                 return 0;
1131         case IOMAP_DELALLOC:
1132                 flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
1133                 break;
1134         case IOMAP_MAPPED:
1135                 break;
1136         case IOMAP_UNWRITTEN:
1137                 flags |= FIEMAP_EXTENT_UNWRITTEN;
1138                 break;
1139         case IOMAP_INLINE:
1140                 flags |= FIEMAP_EXTENT_DATA_INLINE;
1141                 break;
1142         }
1143
1144         if (iomap->flags & IOMAP_F_MERGED)
1145                 flags |= FIEMAP_EXTENT_MERGED;
1146         if (iomap->flags & IOMAP_F_SHARED)
1147                 flags |= FIEMAP_EXTENT_SHARED;
1148
1149         return fiemap_fill_next_extent(fi, iomap->offset,
1150                         iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0,
1151                         iomap->length, flags);
1152 }
1153
1154 static loff_t
1155 iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
1156                 struct iomap *iomap)
1157 {
1158         struct fiemap_ctx *ctx = data;
1159         loff_t ret = length;
1160
1161         if (iomap->type == IOMAP_HOLE)
1162                 return length;
1163
1164         ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
1165         ctx->prev = *iomap;
1166         switch (ret) {
1167         case 0:         /* success */
1168                 return length;
1169         case 1:         /* extent array full */
1170                 return 0;
1171         default:
1172                 return ret;
1173         }
1174 }
1175
1176 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
1177                 loff_t start, loff_t len, const struct iomap_ops *ops)
1178 {
1179         struct fiemap_ctx ctx;
1180         loff_t ret;
1181
1182         memset(&ctx, 0, sizeof(ctx));
1183         ctx.fi = fi;
1184         ctx.prev.type = IOMAP_HOLE;
1185
1186         ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
1187         if (ret)
1188                 return ret;
1189
1190         if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
1191                 ret = filemap_write_and_wait(inode->i_mapping);
1192                 if (ret)
1193                         return ret;
1194         }
1195
1196         while (len > 0) {
1197                 ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
1198                                 iomap_fiemap_actor);
1199                 /* inode with no (attribute) mapping will give ENOENT */
1200                 if (ret == -ENOENT)
1201                         break;
1202                 if (ret < 0)
1203                         return ret;
1204                 if (ret == 0)
1205                         break;
1206
1207                 start += ret;
1208                 len -= ret;
1209         }
1210
1211         if (ctx.prev.type != IOMAP_HOLE) {
1212                 ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
1213                 if (ret < 0)
1214                         return ret;
1215         }
1216
1217         return 0;
1218 }
1219 EXPORT_SYMBOL_GPL(iomap_fiemap);
1220
1221 /*
1222  * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
1223  * Returns true if found and updates @lastoff to the offset in file.
1224  */
1225 static bool
1226 page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
1227                 int whence)
1228 {
1229         const struct address_space_operations *ops = inode->i_mapping->a_ops;
1230         unsigned int bsize = i_blocksize(inode), off;
1231         bool seek_data = whence == SEEK_DATA;
1232         loff_t poff = page_offset(page);
1233
1234         if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
1235                 return false;
1236
1237         if (*lastoff < poff) {
1238                 /*
1239                  * Last offset smaller than the start of the page means we found
1240                  * a hole:
1241                  */
1242                 if (whence == SEEK_HOLE)
1243                         return true;
1244                 *lastoff = poff;
1245         }
1246
1247         /*
1248          * Just check the page unless we can and should check block ranges:
1249          */
1250         if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
1251                 return PageUptodate(page) == seek_data;
1252
1253         lock_page(page);
1254         if (unlikely(page->mapping != inode->i_mapping))
1255                 goto out_unlock_not_found;
1256
1257         for (off = 0; off < PAGE_SIZE; off += bsize) {
1258                 if (offset_in_page(*lastoff) >= off + bsize)
1259                         continue;
1260                 if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
1261                         unlock_page(page);
1262                         return true;
1263                 }
1264                 *lastoff = poff + off + bsize;
1265         }
1266
1267 out_unlock_not_found:
1268         unlock_page(page);
1269         return false;
1270 }
1271
1272 /*
1273  * Seek for SEEK_DATA / SEEK_HOLE in the page cache.
1274  *
1275  * Within unwritten extents, the page cache determines which parts are holes
1276  * and which are data: uptodate buffer heads count as data; everything else
1277  * counts as a hole.
1278  *
1279  * Returns the resulting offset on successs, and -ENOENT otherwise.
1280  */
1281 static loff_t
1282 page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
1283                 int whence)
1284 {
1285         pgoff_t index = offset >> PAGE_SHIFT;
1286         pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
1287         loff_t lastoff = offset;
1288         struct pagevec pvec;
1289
1290         if (length <= 0)
1291                 return -ENOENT;
1292
1293         pagevec_init(&pvec);
1294
1295         do {
1296                 unsigned nr_pages, i;
1297
1298                 nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
1299                                                 end - 1);
1300                 if (nr_pages == 0)
1301                         break;
1302
1303                 for (i = 0; i < nr_pages; i++) {
1304                         struct page *page = pvec.pages[i];
1305
1306                         if (page_seek_hole_data(inode, page, &lastoff, whence))
1307                                 goto check_range;
1308                         lastoff = page_offset(page) + PAGE_SIZE;
1309                 }
1310                 pagevec_release(&pvec);
1311         } while (index < end);
1312
1313         /* When no page at lastoff and we are not done, we found a hole. */
1314         if (whence != SEEK_HOLE)
1315                 goto not_found;
1316
1317 check_range:
1318         if (lastoff < offset + length)
1319                 goto out;
1320 not_found:
1321         lastoff = -ENOENT;
1322 out:
1323         pagevec_release(&pvec);
1324         return lastoff;
1325 }
1326
1327
1328 static loff_t
1329 iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
1330                       void *data, struct iomap *iomap)
1331 {
1332         switch (iomap->type) {
1333         case IOMAP_UNWRITTEN:
1334                 offset = page_cache_seek_hole_data(inode, offset, length,
1335                                                    SEEK_HOLE);
1336                 if (offset < 0)
1337                         return length;
1338                 /* fall through */
1339         case IOMAP_HOLE:
1340                 *(loff_t *)data = offset;
1341                 return 0;
1342         default:
1343                 return length;
1344         }
1345 }
1346
1347 loff_t
1348 iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
1349 {
1350         loff_t size = i_size_read(inode);
1351         loff_t length = size - offset;
1352         loff_t ret;
1353
1354         /* Nothing to be found before or beyond the end of the file. */
1355         if (offset < 0 || offset >= size)
1356                 return -ENXIO;
1357
1358         while (length > 0) {
1359                 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
1360                                   &offset, iomap_seek_hole_actor);
1361                 if (ret < 0)
1362                         return ret;
1363                 if (ret == 0)
1364                         break;
1365
1366                 offset += ret;
1367                 length -= ret;
1368         }
1369
1370         return offset;
1371 }
1372 EXPORT_SYMBOL_GPL(iomap_seek_hole);
1373
1374 static loff_t
1375 iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
1376                       void *data, struct iomap *iomap)
1377 {
1378         switch (iomap->type) {
1379         case IOMAP_HOLE:
1380                 return length;
1381         case IOMAP_UNWRITTEN:
1382                 offset = page_cache_seek_hole_data(inode, offset, length,
1383                                                    SEEK_DATA);
1384                 if (offset < 0)
1385                         return length;
1386                 /*FALLTHRU*/
1387         default:
1388                 *(loff_t *)data = offset;
1389                 return 0;
1390         }
1391 }
1392
1393 loff_t
1394 iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
1395 {
1396         loff_t size = i_size_read(inode);
1397         loff_t length = size - offset;
1398         loff_t ret;
1399
1400         /* Nothing to be found before or beyond the end of the file. */
1401         if (offset < 0 || offset >= size)
1402                 return -ENXIO;
1403
1404         while (length > 0) {
1405                 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
1406                                   &offset, iomap_seek_data_actor);
1407                 if (ret < 0)
1408                         return ret;
1409                 if (ret == 0)
1410                         break;
1411
1412                 offset += ret;
1413                 length -= ret;
1414         }
1415
1416         if (length <= 0)
1417                 return -ENXIO;
1418         return offset;
1419 }
1420 EXPORT_SYMBOL_GPL(iomap_seek_data);
1421
1422 /*
1423  * Private flags for iomap_dio, must not overlap with the public ones in
1424  * iomap.h:
1425  */
1426 #define IOMAP_DIO_WRITE_FUA     (1 << 28)
1427 #define IOMAP_DIO_NEED_SYNC     (1 << 29)
1428 #define IOMAP_DIO_WRITE         (1 << 30)
1429 #define IOMAP_DIO_DIRTY         (1 << 31)
1430
1431 struct iomap_dio {
1432         struct kiocb            *iocb;
1433         iomap_dio_end_io_t      *end_io;
1434         loff_t                  i_size;
1435         loff_t                  size;
1436         atomic_t                ref;
1437         unsigned                flags;
1438         int                     error;
1439         bool                    wait_for_completion;
1440
1441         union {
1442                 /* used during submission and for synchronous completion: */
1443                 struct {
1444                         struct iov_iter         *iter;
1445                         struct task_struct      *waiter;
1446                         struct request_queue    *last_queue;
1447                         blk_qc_t                cookie;
1448                 } submit;
1449
1450                 /* used for aio completion: */
1451                 struct {
1452                         struct work_struct      work;
1453                 } aio;
1454         };
1455 };
1456
1457 static ssize_t iomap_dio_complete(struct iomap_dio *dio)
1458 {
1459         struct kiocb *iocb = dio->iocb;
1460         struct inode *inode = file_inode(iocb->ki_filp);
1461         loff_t offset = iocb->ki_pos;
1462         ssize_t ret;
1463
1464         if (dio->end_io) {
1465                 ret = dio->end_io(iocb,
1466                                 dio->error ? dio->error : dio->size,
1467                                 dio->flags);
1468         } else {
1469                 ret = dio->error;
1470         }
1471
1472         if (likely(!ret)) {
1473                 ret = dio->size;
1474                 /* check for short read */
1475                 if (offset + ret > dio->i_size &&
1476                     !(dio->flags & IOMAP_DIO_WRITE))
1477                         ret = dio->i_size - offset;
1478                 iocb->ki_pos += ret;
1479         }
1480
1481         /*
1482          * Try again to invalidate clean pages which might have been cached by
1483          * non-direct readahead, or faulted in by get_user_pages() if the source
1484          * of the write was an mmap'ed region of the file we're writing.  Either
1485          * one is a pretty crazy thing to do, so we don't support it 100%.  If
1486          * this invalidation fails, tough, the write still worked...
1487          *
1488          * And this page cache invalidation has to be after dio->end_io(), as
1489          * some filesystems convert unwritten extents to real allocations in
1490          * end_io() when necessary, otherwise a racing buffer read would cache
1491          * zeros from unwritten extents.
1492          */
1493         if (!dio->error &&
1494             (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) {
1495                 int err;
1496                 err = invalidate_inode_pages2_range(inode->i_mapping,
1497                                 offset >> PAGE_SHIFT,
1498                                 (offset + dio->size - 1) >> PAGE_SHIFT);
1499                 if (err)
1500                         dio_warn_stale_pagecache(iocb->ki_filp);
1501         }
1502
1503         /*
1504          * If this is a DSYNC write, make sure we push it to stable storage now
1505          * that we've written data.
1506          */
1507         if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
1508                 ret = generic_write_sync(iocb, ret);
1509
1510         inode_dio_end(file_inode(iocb->ki_filp));
1511         kfree(dio);
1512
1513         return ret;
1514 }
1515
1516 static void iomap_dio_complete_work(struct work_struct *work)
1517 {
1518         struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
1519         struct kiocb *iocb = dio->iocb;
1520
1521         iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);
1522 }
1523
1524 /*
1525  * Set an error in the dio if none is set yet.  We have to use cmpxchg
1526  * as the submission context and the completion context(s) can race to
1527  * update the error.
1528  */
1529 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
1530 {
1531         cmpxchg(&dio->error, 0, ret);
1532 }
1533
1534 static void iomap_dio_bio_end_io(struct bio *bio)
1535 {
1536         struct iomap_dio *dio = bio->bi_private;
1537         bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
1538
1539         if (bio->bi_status)
1540                 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
1541
1542         if (atomic_dec_and_test(&dio->ref)) {
1543                 if (dio->wait_for_completion) {
1544                         struct task_struct *waiter = dio->submit.waiter;
1545                         WRITE_ONCE(dio->submit.waiter, NULL);
1546                         wake_up_process(waiter);
1547                 } else if (dio->flags & IOMAP_DIO_WRITE) {
1548                         struct inode *inode = file_inode(dio->iocb->ki_filp);
1549
1550                         INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
1551                         queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
1552                 } else {
1553                         iomap_dio_complete_work(&dio->aio.work);
1554                 }
1555         }
1556
1557         if (should_dirty) {
1558                 bio_check_pages_dirty(bio);
1559         } else {
1560                 struct bio_vec *bvec;
1561                 int i;
1562
1563                 bio_for_each_segment_all(bvec, bio, i)
1564                         put_page(bvec->bv_page);
1565                 bio_put(bio);
1566         }
1567 }
1568
1569 static blk_qc_t
1570 iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
1571                 unsigned len)
1572 {
1573         struct page *page = ZERO_PAGE(0);
1574         struct bio *bio;
1575
1576         bio = bio_alloc(GFP_KERNEL, 1);
1577         bio_set_dev(bio, iomap->bdev);
1578         bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
1579         bio->bi_private = dio;
1580         bio->bi_end_io = iomap_dio_bio_end_io;
1581
1582         get_page(page);
1583         __bio_add_page(bio, page, len, 0);
1584         bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
1585
1586         atomic_inc(&dio->ref);
1587         return submit_bio(bio);
1588 }
1589
1590 static loff_t
1591 iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
1592                 struct iomap_dio *dio, struct iomap *iomap)
1593 {
1594         unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
1595         unsigned int fs_block_size = i_blocksize(inode), pad;
1596         unsigned int align = iov_iter_alignment(dio->submit.iter);
1597         struct iov_iter iter;
1598         struct bio *bio;
1599         bool need_zeroout = false;
1600         bool use_fua = false;
1601         int nr_pages, ret = 0;
1602         size_t copied = 0;
1603
1604         if ((pos | length | align) & ((1 << blkbits) - 1))
1605                 return -EINVAL;
1606
1607         if (iomap->type == IOMAP_UNWRITTEN) {
1608                 dio->flags |= IOMAP_DIO_UNWRITTEN;
1609                 need_zeroout = true;
1610         }
1611
1612         if (iomap->flags & IOMAP_F_SHARED)
1613                 dio->flags |= IOMAP_DIO_COW;
1614
1615         if (iomap->flags & IOMAP_F_NEW) {
1616                 need_zeroout = true;
1617         } else if (iomap->type == IOMAP_MAPPED) {
1618                 /*
1619                  * Use a FUA write if we need datasync semantics, this is a pure
1620                  * data IO that doesn't require any metadata updates (including
1621                  * after IO completion such as unwritten extent conversion) and
1622                  * the underlying device supports FUA. This allows us to avoid
1623                  * cache flushes on IO completion.
1624                  */
1625                 if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
1626                     (dio->flags & IOMAP_DIO_WRITE_FUA) &&
1627                     blk_queue_fua(bdev_get_queue(iomap->bdev)))
1628                         use_fua = true;
1629         }
1630
1631         /*
1632          * Operate on a partial iter trimmed to the extent we were called for.
1633          * We'll update the iter in the dio once we're done with this extent.
1634          */
1635         iter = *dio->submit.iter;
1636         iov_iter_truncate(&iter, length);
1637
1638         nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
1639         if (nr_pages <= 0)
1640                 return nr_pages;
1641
1642         if (need_zeroout) {
1643                 /* zero out from the start of the block to the write offset */
1644                 pad = pos & (fs_block_size - 1);
1645                 if (pad)
1646                         iomap_dio_zero(dio, iomap, pos - pad, pad);
1647         }
1648
1649         do {
1650                 size_t n;
1651                 if (dio->error) {
1652                         iov_iter_revert(dio->submit.iter, copied);
1653                         return 0;
1654                 }
1655
1656                 bio = bio_alloc(GFP_KERNEL, nr_pages);
1657                 bio_set_dev(bio, iomap->bdev);
1658                 bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
1659                 bio->bi_write_hint = dio->iocb->ki_hint;
1660                 bio->bi_ioprio = dio->iocb->ki_ioprio;
1661                 bio->bi_private = dio;
1662                 bio->bi_end_io = iomap_dio_bio_end_io;
1663
1664                 ret = bio_iov_iter_get_pages(bio, &iter);
1665                 if (unlikely(ret)) {
1666                         /*
1667                          * We have to stop part way through an IO. We must fall
1668                          * through to the sub-block tail zeroing here, otherwise
1669                          * this short IO may expose stale data in the tail of
1670                          * the block we haven't written data to.
1671                          */
1672                         bio_put(bio);
1673                         goto zero_tail;
1674                 }
1675
1676                 n = bio->bi_iter.bi_size;
1677                 if (dio->flags & IOMAP_DIO_WRITE) {
1678                         bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
1679                         if (use_fua)
1680                                 bio->bi_opf |= REQ_FUA;
1681                         else
1682                                 dio->flags &= ~IOMAP_DIO_WRITE_FUA;
1683                         task_io_account_write(n);
1684                 } else {
1685                         bio->bi_opf = REQ_OP_READ;
1686                         if (dio->flags & IOMAP_DIO_DIRTY)
1687                                 bio_set_pages_dirty(bio);
1688                 }
1689
1690                 iov_iter_advance(dio->submit.iter, n);
1691
1692                 dio->size += n;
1693                 pos += n;
1694                 copied += n;
1695
1696                 nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
1697
1698                 atomic_inc(&dio->ref);
1699
1700                 dio->submit.last_queue = bdev_get_queue(iomap->bdev);
1701                 dio->submit.cookie = submit_bio(bio);
1702         } while (nr_pages);
1703
1704         /*
1705          * We need to zeroout the tail of a sub-block write if the extent type
1706          * requires zeroing or the write extends beyond EOF. If we don't zero
1707          * the block tail in the latter case, we can expose stale data via mmap
1708          * reads of the EOF block.
1709          */
1710 zero_tail:
1711         if (need_zeroout ||
1712             ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
1713                 /* zero out from the end of the write to the end of the block */
1714                 pad = pos & (fs_block_size - 1);
1715                 if (pad)
1716                         iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
1717         }
1718         return copied ? copied : ret;
1719 }
1720
1721 static loff_t
1722 iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
1723 {
1724         length = iov_iter_zero(length, dio->submit.iter);
1725         dio->size += length;
1726         return length;
1727 }
1728
1729 static loff_t
1730 iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
1731                 struct iomap_dio *dio, struct iomap *iomap)
1732 {
1733         struct iov_iter *iter = dio->submit.iter;
1734         size_t copied;
1735
1736         BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));
1737
1738         if (dio->flags & IOMAP_DIO_WRITE) {
1739                 loff_t size = inode->i_size;
1740
1741                 if (pos > size)
1742                         memset(iomap->inline_data + size, 0, pos - size);
1743                 copied = copy_from_iter(iomap->inline_data + pos, length, iter);
1744                 if (copied) {
1745                         if (pos + copied > size)
1746                                 i_size_write(inode, pos + copied);
1747                         mark_inode_dirty(inode);
1748                 }
1749         } else {
1750                 copied = copy_to_iter(iomap->inline_data + pos, length, iter);
1751         }
1752         dio->size += copied;
1753         return copied;
1754 }
1755
1756 static loff_t
1757 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
1758                 void *data, struct iomap *iomap)
1759 {
1760         struct iomap_dio *dio = data;
1761
1762         switch (iomap->type) {
1763         case IOMAP_HOLE:
1764                 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
1765                         return -EIO;
1766                 return iomap_dio_hole_actor(length, dio);
1767         case IOMAP_UNWRITTEN:
1768                 if (!(dio->flags & IOMAP_DIO_WRITE))
1769                         return iomap_dio_hole_actor(length, dio);
1770                 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
1771         case IOMAP_MAPPED:
1772                 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
1773         case IOMAP_INLINE:
1774                 return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
1775         default:
1776                 WARN_ON_ONCE(1);
1777                 return -EIO;
1778         }
1779 }
1780
1781 /*
1782  * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
1783  * is being issued as AIO or not.  This allows us to optimise pure data writes
1784  * to use REQ_FUA rather than requiring generic_write_sync() to issue a
1785  * REQ_FLUSH post write. This is slightly tricky because a single request here
1786  * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
1787  * may be pure data writes. In that case, we still need to do a full data sync
1788  * completion.
1789  */
1790 ssize_t
1791 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
1792                 const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
1793 {
1794         struct address_space *mapping = iocb->ki_filp->f_mapping;
1795         struct inode *inode = file_inode(iocb->ki_filp);
1796         size_t count = iov_iter_count(iter);
1797         loff_t pos = iocb->ki_pos, start = pos;
1798         loff_t end = iocb->ki_pos + count - 1, ret = 0;
1799         unsigned int flags = IOMAP_DIRECT;
1800         struct blk_plug plug;
1801         struct iomap_dio *dio;
1802
1803         lockdep_assert_held(&inode->i_rwsem);
1804
1805         if (!count)
1806                 return 0;
1807
1808         dio = kmalloc(sizeof(*dio), GFP_KERNEL);
1809         if (!dio)
1810                 return -ENOMEM;
1811
1812         dio->iocb = iocb;
1813         atomic_set(&dio->ref, 1);
1814         dio->size = 0;
1815         dio->i_size = i_size_read(inode);
1816         dio->end_io = end_io;
1817         dio->error = 0;
1818         dio->flags = 0;
1819         dio->wait_for_completion = is_sync_kiocb(iocb);
1820
1821         dio->submit.iter = iter;
1822         dio->submit.waiter = current;
1823         dio->submit.cookie = BLK_QC_T_NONE;
1824         dio->submit.last_queue = NULL;
1825
1826         if (iov_iter_rw(iter) == READ) {
1827                 if (pos >= dio->i_size)
1828                         goto out_free_dio;
1829
1830                 if (iter_is_iovec(iter) && iov_iter_rw(iter) == READ)
1831                         dio->flags |= IOMAP_DIO_DIRTY;
1832         } else {
1833                 flags |= IOMAP_WRITE;
1834                 dio->flags |= IOMAP_DIO_WRITE;
1835
1836                 /* for data sync or sync, we need sync completion processing */
1837                 if (iocb->ki_flags & IOCB_DSYNC)
1838                         dio->flags |= IOMAP_DIO_NEED_SYNC;
1839
1840                 /*
1841                  * For datasync only writes, we optimistically try using FUA for
1842                  * this IO.  Any non-FUA write that occurs will clear this flag,
1843                  * hence we know before completion whether a cache flush is
1844                  * necessary.
1845                  */
1846                 if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC)
1847                         dio->flags |= IOMAP_DIO_WRITE_FUA;
1848         }
1849
1850         if (iocb->ki_flags & IOCB_NOWAIT) {
1851                 if (filemap_range_has_page(mapping, start, end)) {
1852                         ret = -EAGAIN;
1853                         goto out_free_dio;
1854                 }
1855                 flags |= IOMAP_NOWAIT;
1856         }
1857
1858         ret = filemap_write_and_wait_range(mapping, start, end);
1859         if (ret)
1860                 goto out_free_dio;
1861
1862         /*
1863          * Try to invalidate cache pages for the range we're direct
1864          * writing.  If this invalidation fails, tough, the write will
1865          * still work, but racing two incompatible write paths is a
1866          * pretty crazy thing to do, so we don't support it 100%.
1867          */
1868         ret = invalidate_inode_pages2_range(mapping,
1869                         start >> PAGE_SHIFT, end >> PAGE_SHIFT);
1870         if (ret)
1871                 dio_warn_stale_pagecache(iocb->ki_filp);
1872         ret = 0;
1873
1874         if (iov_iter_rw(iter) == WRITE && !dio->wait_for_completion &&
1875             !inode->i_sb->s_dio_done_wq) {
1876                 ret = sb_init_dio_done_wq(inode->i_sb);
1877                 if (ret < 0)
1878                         goto out_free_dio;
1879         }
1880
1881         inode_dio_begin(inode);
1882
1883         blk_start_plug(&plug);
1884         do {
1885                 ret = iomap_apply(inode, pos, count, flags, ops, dio,
1886                                 iomap_dio_actor);
1887                 if (ret <= 0) {
1888                         /* magic error code to fall back to buffered I/O */
1889                         if (ret == -ENOTBLK) {
1890                                 dio->wait_for_completion = true;
1891                                 ret = 0;
1892                         }
1893                         break;
1894                 }
1895                 pos += ret;
1896
1897                 if (iov_iter_rw(iter) == READ && pos >= dio->i_size)
1898                         break;
1899         } while ((count = iov_iter_count(iter)) > 0);
1900         blk_finish_plug(&plug);
1901
1902         if (ret < 0)
1903                 iomap_dio_set_error(dio, ret);
1904
1905         /*
1906          * If all the writes we issued were FUA, we don't need to flush the
1907          * cache on IO completion. Clear the sync flag for this case.
1908          */
1909         if (dio->flags & IOMAP_DIO_WRITE_FUA)
1910                 dio->flags &= ~IOMAP_DIO_NEED_SYNC;
1911
1912         if (!atomic_dec_and_test(&dio->ref)) {
1913                 if (!dio->wait_for_completion)
1914                         return -EIOCBQUEUED;
1915
1916                 for (;;) {
1917                         set_current_state(TASK_UNINTERRUPTIBLE);
1918                         if (!READ_ONCE(dio->submit.waiter))
1919                                 break;
1920
1921                         if (!(iocb->ki_flags & IOCB_HIPRI) ||
1922                             !dio->submit.last_queue ||
1923                             !blk_poll(dio->submit.last_queue,
1924                                          dio->submit.cookie))
1925                                 io_schedule();
1926                 }
1927                 __set_current_state(TASK_RUNNING);
1928         }
1929
1930         ret = iomap_dio_complete(dio);
1931
1932         return ret;
1933
1934 out_free_dio:
1935         kfree(dio);
1936         return ret;
1937 }
1938 EXPORT_SYMBOL_GPL(iomap_dio_rw);
1939
1940 /* Swapfile activation */
1941
1942 #ifdef CONFIG_SWAP
1943 struct iomap_swapfile_info {
1944         struct iomap iomap;             /* accumulated iomap */
1945         struct swap_info_struct *sis;
1946         uint64_t lowest_ppage;          /* lowest physical addr seen (pages) */
1947         uint64_t highest_ppage;         /* highest physical addr seen (pages) */
1948         unsigned long nr_pages;         /* number of pages collected */
1949         int nr_extents;                 /* extent count */
1950 };
1951
1952 /*
1953  * Collect physical extents for this swap file.  Physical extents reported to
1954  * the swap code must be trimmed to align to a page boundary.  The logical
1955  * offset within the file is irrelevant since the swapfile code maps logical
1956  * page numbers of the swap device to the physical page-aligned extents.
1957  */
1958 static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
1959 {
1960         struct iomap *iomap = &isi->iomap;
1961         unsigned long nr_pages;
1962         uint64_t first_ppage;
1963         uint64_t first_ppage_reported;
1964         uint64_t next_ppage;
1965         int error;
1966
1967         /*
1968          * Round the start up and the end down so that the physical
1969          * extent aligns to a page boundary.
1970          */
1971         first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
1972         next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
1973                         PAGE_SHIFT;
1974
1975         /* Skip too-short physical extents. */
1976         if (first_ppage >= next_ppage)
1977                 return 0;
1978         nr_pages = next_ppage - first_ppage;
1979
1980         /*
1981          * Calculate how much swap space we're adding; the first page contains
1982          * the swap header and doesn't count.  The mm still wants that first
1983          * page fed to add_swap_extent, however.
1984          */
1985         first_ppage_reported = first_ppage;
1986         if (iomap->offset == 0)
1987                 first_ppage_reported++;
1988         if (isi->lowest_ppage > first_ppage_reported)
1989                 isi->lowest_ppage = first_ppage_reported;
1990         if (isi->highest_ppage < (next_ppage - 1))
1991                 isi->highest_ppage = next_ppage - 1;
1992
1993         /* Add extent, set up for the next call. */
1994         error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
1995         if (error < 0)
1996                 return error;
1997         isi->nr_extents += error;
1998         isi->nr_pages += nr_pages;
1999         return 0;
2000 }
2001
2002 /*
2003  * Accumulate iomaps for this swap file.  We have to accumulate iomaps because
2004  * swap only cares about contiguous page-aligned physical extents and makes no
2005  * distinction between written and unwritten extents.
2006  */
2007 static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
2008                 loff_t count, void *data, struct iomap *iomap)
2009 {
2010         struct iomap_swapfile_info *isi = data;
2011         int error;
2012
2013         switch (iomap->type) {
2014         case IOMAP_MAPPED:
2015         case IOMAP_UNWRITTEN:
2016                 /* Only real or unwritten extents. */
2017                 break;
2018         case IOMAP_INLINE:
2019                 /* No inline data. */
2020                 pr_err("swapon: file is inline\n");
2021                 return -EINVAL;
2022         default:
2023                 pr_err("swapon: file has unallocated extents\n");
2024                 return -EINVAL;
2025         }
2026
2027         /* No uncommitted metadata or shared blocks. */
2028         if (iomap->flags & IOMAP_F_DIRTY) {
2029                 pr_err("swapon: file is not committed\n");
2030                 return -EINVAL;
2031         }
2032         if (iomap->flags & IOMAP_F_SHARED) {
2033                 pr_err("swapon: file has shared extents\n");
2034                 return -EINVAL;
2035         }
2036
2037         /* Only one bdev per swap file. */
2038         if (iomap->bdev != isi->sis->bdev) {
2039                 pr_err("swapon: file is on multiple devices\n");
2040                 return -EINVAL;
2041         }
2042
2043         if (isi->iomap.length == 0) {
2044                 /* No accumulated extent, so just store it. */
2045                 memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
2046         } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
2047                 /* Append this to the accumulated extent. */
2048                 isi->iomap.length += iomap->length;
2049         } else {
2050                 /* Otherwise, add the retained iomap and store this one. */
2051                 error = iomap_swapfile_add_extent(isi);
2052                 if (error)
2053                         return error;
2054                 memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
2055         }
2056         return count;
2057 }
2058
2059 /*
2060  * Iterate a swap file's iomaps to construct physical extents that can be
2061  * passed to the swapfile subsystem.
2062  */
2063 int iomap_swapfile_activate(struct swap_info_struct *sis,
2064                 struct file *swap_file, sector_t *pagespan,
2065                 const struct iomap_ops *ops)
2066 {
2067         struct iomap_swapfile_info isi = {
2068                 .sis = sis,
2069                 .lowest_ppage = (sector_t)-1ULL,
2070         };
2071         struct address_space *mapping = swap_file->f_mapping;
2072         struct inode *inode = mapping->host;
2073         loff_t pos = 0;
2074         loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
2075         loff_t ret;
2076
2077         /*
2078          * Persist all file mapping metadata so that we won't have any
2079          * IOMAP_F_DIRTY iomaps.
2080          */
2081         ret = vfs_fsync(swap_file, 1);
2082         if (ret)
2083                 return ret;
2084
2085         while (len > 0) {
2086                 ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
2087                                 ops, &isi, iomap_swapfile_activate_actor);
2088                 if (ret <= 0)
2089                         return ret;
2090
2091                 pos += ret;
2092                 len -= ret;
2093         }
2094
2095         if (isi.iomap.length) {
2096                 ret = iomap_swapfile_add_extent(&isi);
2097                 if (ret)
2098                         return ret;
2099         }
2100
2101         *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
2102         sis->max = isi.nr_pages;
2103         sis->pages = isi.nr_pages - 1;
2104         sis->highest_bit = isi.nr_pages - 1;
2105         return isi.nr_extents;
2106 }
2107 EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
2108 #endif /* CONFIG_SWAP */
2109
2110 static loff_t
2111 iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
2112                 void *data, struct iomap *iomap)
2113 {
2114         sector_t *bno = data, addr;
2115
2116         if (iomap->type == IOMAP_MAPPED) {
2117                 addr = (pos - iomap->offset + iomap->addr) >> inode->i_blkbits;
2118                 if (addr > INT_MAX)
2119                         WARN(1, "would truncate bmap result\n");
2120                 else
2121                         *bno = addr;
2122         }
2123         return 0;
2124 }
2125
2126 /* legacy ->bmap interface.  0 is the error return (!) */
2127 sector_t
2128 iomap_bmap(struct address_space *mapping, sector_t bno,
2129                 const struct iomap_ops *ops)
2130 {
2131         struct inode *inode = mapping->host;
2132         loff_t pos = bno << inode->i_blkbits;
2133         unsigned blocksize = i_blocksize(inode);
2134
2135         if (filemap_write_and_wait(mapping))
2136                 return 0;
2137
2138         bno = 0;
2139         iomap_apply(inode, pos, blocksize, 0, ops, &bno, iomap_bmap_actor);
2140         return bno;
2141 }
2142 EXPORT_SYMBOL_GPL(iomap_bmap);