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