1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * fs/mpage.c |
4 | * |
5 | * Copyright (C) 2002, Linus Torvalds. |
6 | * |
7 | * Contains functions related to preparing and submitting BIOs which contain |
8 | * multiple pagecache pages. |
9 | * |
10 | * 15May2002 Andrew Morton |
11 | * Initial version |
12 | * 27Jun2002 axboe@suse.de |
13 | * use bio_add_page() to build bio's just the right size |
14 | */ |
15 | |
16 | #include <linux/kernel.h> |
17 | #include <linux/export.h> |
18 | #include <linux/mm.h> |
19 | #include <linux/kdev_t.h> |
20 | #include <linux/gfp.h> |
21 | #include <linux/bio.h> |
22 | #include <linux/fs.h> |
23 | #include <linux/buffer_head.h> |
24 | #include <linux/blkdev.h> |
25 | #include <linux/highmem.h> |
26 | #include <linux/prefetch.h> |
27 | #include <linux/mpage.h> |
28 | #include <linux/mm_inline.h> |
29 | #include <linux/writeback.h> |
30 | #include <linux/backing-dev.h> |
31 | #include <linux/pagevec.h> |
32 | #include "internal.h" |
33 | |
34 | /* |
35 | * I/O completion handler for multipage BIOs. |
36 | * |
37 | * The mpage code never puts partial pages into a BIO (except for end-of-file). |
38 | * If a page does not map to a contiguous run of blocks then it simply falls |
39 | * back to block_read_full_folio(). |
40 | * |
41 | * Why is this? If a page's completion depends on a number of different BIOs |
42 | * which can complete in any order (or at the same time) then determining the |
43 | * status of that page is hard. See end_buffer_async_read() for the details. |
44 | * There is no point in duplicating all that complexity. |
45 | */ |
46 | static void mpage_read_end_io(struct bio *bio) |
47 | { |
48 | struct folio_iter fi; |
49 | int err = blk_status_to_errno(status: bio->bi_status); |
50 | |
51 | bio_for_each_folio_all(fi, bio) { |
52 | if (err) |
53 | folio_set_error(folio: fi.folio); |
54 | else |
55 | folio_mark_uptodate(folio: fi.folio); |
56 | folio_unlock(folio: fi.folio); |
57 | } |
58 | |
59 | bio_put(bio); |
60 | } |
61 | |
62 | static void mpage_write_end_io(struct bio *bio) |
63 | { |
64 | struct folio_iter fi; |
65 | int err = blk_status_to_errno(status: bio->bi_status); |
66 | |
67 | bio_for_each_folio_all(fi, bio) { |
68 | if (err) { |
69 | folio_set_error(folio: fi.folio); |
70 | mapping_set_error(mapping: fi.folio->mapping, error: err); |
71 | } |
72 | folio_end_writeback(folio: fi.folio); |
73 | } |
74 | |
75 | bio_put(bio); |
76 | } |
77 | |
78 | static struct bio *mpage_bio_submit_read(struct bio *bio) |
79 | { |
80 | bio->bi_end_io = mpage_read_end_io; |
81 | guard_bio_eod(bio); |
82 | submit_bio(bio); |
83 | return NULL; |
84 | } |
85 | |
86 | static struct bio *mpage_bio_submit_write(struct bio *bio) |
87 | { |
88 | bio->bi_end_io = mpage_write_end_io; |
89 | guard_bio_eod(bio); |
90 | submit_bio(bio); |
91 | return NULL; |
92 | } |
93 | |
94 | /* |
95 | * support function for mpage_readahead. The fs supplied get_block might |
96 | * return an up to date buffer. This is used to map that buffer into |
97 | * the page, which allows read_folio to avoid triggering a duplicate call |
98 | * to get_block. |
99 | * |
100 | * The idea is to avoid adding buffers to pages that don't already have |
101 | * them. So when the buffer is up to date and the page size == block size, |
102 | * this marks the page up to date instead of adding new buffers. |
103 | */ |
104 | static void map_buffer_to_folio(struct folio *folio, struct buffer_head *bh, |
105 | int page_block) |
106 | { |
107 | struct inode *inode = folio->mapping->host; |
108 | struct buffer_head *page_bh, *head; |
109 | int block = 0; |
110 | |
111 | head = folio_buffers(folio); |
112 | if (!head) { |
113 | /* |
114 | * don't make any buffers if there is only one buffer on |
115 | * the folio and the folio just needs to be set up to date |
116 | */ |
117 | if (inode->i_blkbits == PAGE_SHIFT && |
118 | buffer_uptodate(bh)) { |
119 | folio_mark_uptodate(folio); |
120 | return; |
121 | } |
122 | head = create_empty_buffers(folio, blocksize: i_blocksize(node: inode), b_state: 0); |
123 | } |
124 | |
125 | page_bh = head; |
126 | do { |
127 | if (block == page_block) { |
128 | page_bh->b_state = bh->b_state; |
129 | page_bh->b_bdev = bh->b_bdev; |
130 | page_bh->b_blocknr = bh->b_blocknr; |
131 | break; |
132 | } |
133 | page_bh = page_bh->b_this_page; |
134 | block++; |
135 | } while (page_bh != head); |
136 | } |
137 | |
138 | struct mpage_readpage_args { |
139 | struct bio *bio; |
140 | struct folio *folio; |
141 | unsigned int nr_pages; |
142 | bool is_readahead; |
143 | sector_t last_block_in_bio; |
144 | struct buffer_head map_bh; |
145 | unsigned long first_logical_block; |
146 | get_block_t *get_block; |
147 | }; |
148 | |
149 | /* |
150 | * This is the worker routine which does all the work of mapping the disk |
151 | * blocks and constructs largest possible bios, submits them for IO if the |
152 | * blocks are not contiguous on the disk. |
153 | * |
154 | * We pass a buffer_head back and forth and use its buffer_mapped() flag to |
155 | * represent the validity of its disk mapping and to decide when to do the next |
156 | * get_block() call. |
157 | */ |
158 | static struct bio *do_mpage_readpage(struct mpage_readpage_args *args) |
159 | { |
160 | struct folio *folio = args->folio; |
161 | struct inode *inode = folio->mapping->host; |
162 | const unsigned blkbits = inode->i_blkbits; |
163 | const unsigned blocks_per_page = PAGE_SIZE >> blkbits; |
164 | const unsigned blocksize = 1 << blkbits; |
165 | struct buffer_head *map_bh = &args->map_bh; |
166 | sector_t block_in_file; |
167 | sector_t last_block; |
168 | sector_t last_block_in_file; |
169 | sector_t first_block; |
170 | unsigned page_block; |
171 | unsigned first_hole = blocks_per_page; |
172 | struct block_device *bdev = NULL; |
173 | int length; |
174 | int fully_mapped = 1; |
175 | blk_opf_t opf = REQ_OP_READ; |
176 | unsigned nblocks; |
177 | unsigned relative_block; |
178 | gfp_t gfp = mapping_gfp_constraint(mapping: folio->mapping, GFP_KERNEL); |
179 | |
180 | /* MAX_BUF_PER_PAGE, for example */ |
181 | VM_BUG_ON_FOLIO(folio_test_large(folio), folio); |
182 | |
183 | if (args->is_readahead) { |
184 | opf |= REQ_RAHEAD; |
185 | gfp |= __GFP_NORETRY | __GFP_NOWARN; |
186 | } |
187 | |
188 | if (folio_buffers(folio)) |
189 | goto confused; |
190 | |
191 | block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits); |
192 | last_block = block_in_file + args->nr_pages * blocks_per_page; |
193 | last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits; |
194 | if (last_block > last_block_in_file) |
195 | last_block = last_block_in_file; |
196 | page_block = 0; |
197 | |
198 | /* |
199 | * Map blocks using the result from the previous get_blocks call first. |
200 | */ |
201 | nblocks = map_bh->b_size >> blkbits; |
202 | if (buffer_mapped(bh: map_bh) && |
203 | block_in_file > args->first_logical_block && |
204 | block_in_file < (args->first_logical_block + nblocks)) { |
205 | unsigned map_offset = block_in_file - args->first_logical_block; |
206 | unsigned last = nblocks - map_offset; |
207 | |
208 | first_block = map_bh->b_blocknr + map_offset; |
209 | for (relative_block = 0; ; relative_block++) { |
210 | if (relative_block == last) { |
211 | clear_buffer_mapped(bh: map_bh); |
212 | break; |
213 | } |
214 | if (page_block == blocks_per_page) |
215 | break; |
216 | page_block++; |
217 | block_in_file++; |
218 | } |
219 | bdev = map_bh->b_bdev; |
220 | } |
221 | |
222 | /* |
223 | * Then do more get_blocks calls until we are done with this folio. |
224 | */ |
225 | map_bh->b_folio = folio; |
226 | while (page_block < blocks_per_page) { |
227 | map_bh->b_state = 0; |
228 | map_bh->b_size = 0; |
229 | |
230 | if (block_in_file < last_block) { |
231 | map_bh->b_size = (last_block-block_in_file) << blkbits; |
232 | if (args->get_block(inode, block_in_file, map_bh, 0)) |
233 | goto confused; |
234 | args->first_logical_block = block_in_file; |
235 | } |
236 | |
237 | if (!buffer_mapped(bh: map_bh)) { |
238 | fully_mapped = 0; |
239 | if (first_hole == blocks_per_page) |
240 | first_hole = page_block; |
241 | page_block++; |
242 | block_in_file++; |
243 | continue; |
244 | } |
245 | |
246 | /* some filesystems will copy data into the page during |
247 | * the get_block call, in which case we don't want to |
248 | * read it again. map_buffer_to_folio copies the data |
249 | * we just collected from get_block into the folio's buffers |
250 | * so read_folio doesn't have to repeat the get_block call |
251 | */ |
252 | if (buffer_uptodate(bh: map_bh)) { |
253 | map_buffer_to_folio(folio, bh: map_bh, page_block); |
254 | goto confused; |
255 | } |
256 | |
257 | if (first_hole != blocks_per_page) |
258 | goto confused; /* hole -> non-hole */ |
259 | |
260 | /* Contiguous blocks? */ |
261 | if (!page_block) |
262 | first_block = map_bh->b_blocknr; |
263 | else if (first_block + page_block != map_bh->b_blocknr) |
264 | goto confused; |
265 | nblocks = map_bh->b_size >> blkbits; |
266 | for (relative_block = 0; ; relative_block++) { |
267 | if (relative_block == nblocks) { |
268 | clear_buffer_mapped(bh: map_bh); |
269 | break; |
270 | } else if (page_block == blocks_per_page) |
271 | break; |
272 | page_block++; |
273 | block_in_file++; |
274 | } |
275 | bdev = map_bh->b_bdev; |
276 | } |
277 | |
278 | if (first_hole != blocks_per_page) { |
279 | folio_zero_segment(folio, start: first_hole << blkbits, PAGE_SIZE); |
280 | if (first_hole == 0) { |
281 | folio_mark_uptodate(folio); |
282 | folio_unlock(folio); |
283 | goto out; |
284 | } |
285 | } else if (fully_mapped) { |
286 | folio_set_mappedtodisk(folio); |
287 | } |
288 | |
289 | /* |
290 | * This folio will go to BIO. Do we need to send this BIO off first? |
291 | */ |
292 | if (args->bio && (args->last_block_in_bio != first_block - 1)) |
293 | args->bio = mpage_bio_submit_read(bio: args->bio); |
294 | |
295 | alloc_new: |
296 | if (args->bio == NULL) { |
297 | args->bio = bio_alloc(bdev, nr_vecs: bio_max_segs(nr_segs: args->nr_pages), opf, |
298 | gfp_mask: gfp); |
299 | if (args->bio == NULL) |
300 | goto confused; |
301 | args->bio->bi_iter.bi_sector = first_block << (blkbits - 9); |
302 | } |
303 | |
304 | length = first_hole << blkbits; |
305 | if (!bio_add_folio(bio: args->bio, folio, len: length, off: 0)) { |
306 | args->bio = mpage_bio_submit_read(bio: args->bio); |
307 | goto alloc_new; |
308 | } |
309 | |
310 | relative_block = block_in_file - args->first_logical_block; |
311 | nblocks = map_bh->b_size >> blkbits; |
312 | if ((buffer_boundary(bh: map_bh) && relative_block == nblocks) || |
313 | (first_hole != blocks_per_page)) |
314 | args->bio = mpage_bio_submit_read(bio: args->bio); |
315 | else |
316 | args->last_block_in_bio = first_block + blocks_per_page - 1; |
317 | out: |
318 | return args->bio; |
319 | |
320 | confused: |
321 | if (args->bio) |
322 | args->bio = mpage_bio_submit_read(bio: args->bio); |
323 | if (!folio_test_uptodate(folio)) |
324 | block_read_full_folio(folio, args->get_block); |
325 | else |
326 | folio_unlock(folio); |
327 | goto out; |
328 | } |
329 | |
330 | /** |
331 | * mpage_readahead - start reads against pages |
332 | * @rac: Describes which pages to read. |
333 | * @get_block: The filesystem's block mapper function. |
334 | * |
335 | * This function walks the pages and the blocks within each page, building and |
336 | * emitting large BIOs. |
337 | * |
338 | * If anything unusual happens, such as: |
339 | * |
340 | * - encountering a page which has buffers |
341 | * - encountering a page which has a non-hole after a hole |
342 | * - encountering a page with non-contiguous blocks |
343 | * |
344 | * then this code just gives up and calls the buffer_head-based read function. |
345 | * It does handle a page which has holes at the end - that is a common case: |
346 | * the end-of-file on blocksize < PAGE_SIZE setups. |
347 | * |
348 | * BH_Boundary explanation: |
349 | * |
350 | * There is a problem. The mpage read code assembles several pages, gets all |
351 | * their disk mappings, and then submits them all. That's fine, but obtaining |
352 | * the disk mappings may require I/O. Reads of indirect blocks, for example. |
353 | * |
354 | * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be |
355 | * submitted in the following order: |
356 | * |
357 | * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16 |
358 | * |
359 | * because the indirect block has to be read to get the mappings of blocks |
360 | * 13,14,15,16. Obviously, this impacts performance. |
361 | * |
362 | * So what we do it to allow the filesystem's get_block() function to set |
363 | * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block |
364 | * after this one will require I/O against a block which is probably close to |
365 | * this one. So you should push what I/O you have currently accumulated. |
366 | * |
367 | * This all causes the disk requests to be issued in the correct order. |
368 | */ |
369 | void mpage_readahead(struct readahead_control *rac, get_block_t get_block) |
370 | { |
371 | struct folio *folio; |
372 | struct mpage_readpage_args args = { |
373 | .get_block = get_block, |
374 | .is_readahead = true, |
375 | }; |
376 | |
377 | while ((folio = readahead_folio(ractl: rac))) { |
378 | prefetchw(x: &folio->flags); |
379 | args.folio = folio; |
380 | args.nr_pages = readahead_count(rac); |
381 | args.bio = do_mpage_readpage(args: &args); |
382 | } |
383 | if (args.bio) |
384 | mpage_bio_submit_read(bio: args.bio); |
385 | } |
386 | EXPORT_SYMBOL(mpage_readahead); |
387 | |
388 | /* |
389 | * This isn't called much at all |
390 | */ |
391 | int mpage_read_folio(struct folio *folio, get_block_t get_block) |
392 | { |
393 | struct mpage_readpage_args args = { |
394 | .folio = folio, |
395 | .nr_pages = 1, |
396 | .get_block = get_block, |
397 | }; |
398 | |
399 | args.bio = do_mpage_readpage(args: &args); |
400 | if (args.bio) |
401 | mpage_bio_submit_read(bio: args.bio); |
402 | return 0; |
403 | } |
404 | EXPORT_SYMBOL(mpage_read_folio); |
405 | |
406 | /* |
407 | * Writing is not so simple. |
408 | * |
409 | * If the page has buffers then they will be used for obtaining the disk |
410 | * mapping. We only support pages which are fully mapped-and-dirty, with a |
411 | * special case for pages which are unmapped at the end: end-of-file. |
412 | * |
413 | * If the page has no buffers (preferred) then the page is mapped here. |
414 | * |
415 | * If all blocks are found to be contiguous then the page can go into the |
416 | * BIO. Otherwise fall back to the mapping's writepage(). |
417 | * |
418 | * FIXME: This code wants an estimate of how many pages are still to be |
419 | * written, so it can intelligently allocate a suitably-sized BIO. For now, |
420 | * just allocate full-size (16-page) BIOs. |
421 | */ |
422 | |
423 | struct mpage_data { |
424 | struct bio *bio; |
425 | sector_t last_block_in_bio; |
426 | get_block_t *get_block; |
427 | }; |
428 | |
429 | /* |
430 | * We have our BIO, so we can now mark the buffers clean. Make |
431 | * sure to only clean buffers which we know we'll be writing. |
432 | */ |
433 | static void clean_buffers(struct folio *folio, unsigned first_unmapped) |
434 | { |
435 | unsigned buffer_counter = 0; |
436 | struct buffer_head *bh, *head = folio_buffers(folio); |
437 | |
438 | if (!head) |
439 | return; |
440 | bh = head; |
441 | |
442 | do { |
443 | if (buffer_counter++ == first_unmapped) |
444 | break; |
445 | clear_buffer_dirty(bh); |
446 | bh = bh->b_this_page; |
447 | } while (bh != head); |
448 | |
449 | /* |
450 | * we cannot drop the bh if the page is not uptodate or a concurrent |
451 | * read_folio would fail to serialize with the bh and it would read from |
452 | * disk before we reach the platter. |
453 | */ |
454 | if (buffer_heads_over_limit && folio_test_uptodate(folio)) |
455 | try_to_free_buffers(folio); |
456 | } |
457 | |
458 | static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, |
459 | void *data) |
460 | { |
461 | struct mpage_data *mpd = data; |
462 | struct bio *bio = mpd->bio; |
463 | struct address_space *mapping = folio->mapping; |
464 | struct inode *inode = mapping->host; |
465 | const unsigned blkbits = inode->i_blkbits; |
466 | const unsigned blocks_per_page = PAGE_SIZE >> blkbits; |
467 | sector_t last_block; |
468 | sector_t block_in_file; |
469 | sector_t first_block; |
470 | unsigned page_block; |
471 | unsigned first_unmapped = blocks_per_page; |
472 | struct block_device *bdev = NULL; |
473 | int boundary = 0; |
474 | sector_t boundary_block = 0; |
475 | struct block_device *boundary_bdev = NULL; |
476 | size_t length; |
477 | struct buffer_head map_bh; |
478 | loff_t i_size = i_size_read(inode); |
479 | int ret = 0; |
480 | struct buffer_head *head = folio_buffers(folio); |
481 | |
482 | if (head) { |
483 | struct buffer_head *bh = head; |
484 | |
485 | /* If they're all mapped and dirty, do it */ |
486 | page_block = 0; |
487 | do { |
488 | BUG_ON(buffer_locked(bh)); |
489 | if (!buffer_mapped(bh)) { |
490 | /* |
491 | * unmapped dirty buffers are created by |
492 | * block_dirty_folio -> mmapped data |
493 | */ |
494 | if (buffer_dirty(bh)) |
495 | goto confused; |
496 | if (first_unmapped == blocks_per_page) |
497 | first_unmapped = page_block; |
498 | continue; |
499 | } |
500 | |
501 | if (first_unmapped != blocks_per_page) |
502 | goto confused; /* hole -> non-hole */ |
503 | |
504 | if (!buffer_dirty(bh) || !buffer_uptodate(bh)) |
505 | goto confused; |
506 | if (page_block) { |
507 | if (bh->b_blocknr != first_block + page_block) |
508 | goto confused; |
509 | } else { |
510 | first_block = bh->b_blocknr; |
511 | } |
512 | page_block++; |
513 | boundary = buffer_boundary(bh); |
514 | if (boundary) { |
515 | boundary_block = bh->b_blocknr; |
516 | boundary_bdev = bh->b_bdev; |
517 | } |
518 | bdev = bh->b_bdev; |
519 | } while ((bh = bh->b_this_page) != head); |
520 | |
521 | if (first_unmapped) |
522 | goto page_is_mapped; |
523 | |
524 | /* |
525 | * Page has buffers, but they are all unmapped. The page was |
526 | * created by pagein or read over a hole which was handled by |
527 | * block_read_full_folio(). If this address_space is also |
528 | * using mpage_readahead then this can rarely happen. |
529 | */ |
530 | goto confused; |
531 | } |
532 | |
533 | /* |
534 | * The page has no buffers: map it to disk |
535 | */ |
536 | BUG_ON(!folio_test_uptodate(folio)); |
537 | block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits); |
538 | /* |
539 | * Whole page beyond EOF? Skip allocating blocks to avoid leaking |
540 | * space. |
541 | */ |
542 | if (block_in_file >= (i_size + (1 << blkbits) - 1) >> blkbits) |
543 | goto page_is_mapped; |
544 | last_block = (i_size - 1) >> blkbits; |
545 | map_bh.b_folio = folio; |
546 | for (page_block = 0; page_block < blocks_per_page; ) { |
547 | |
548 | map_bh.b_state = 0; |
549 | map_bh.b_size = 1 << blkbits; |
550 | if (mpd->get_block(inode, block_in_file, &map_bh, 1)) |
551 | goto confused; |
552 | if (!buffer_mapped(bh: &map_bh)) |
553 | goto confused; |
554 | if (buffer_new(bh: &map_bh)) |
555 | clean_bdev_bh_alias(bh: &map_bh); |
556 | if (buffer_boundary(bh: &map_bh)) { |
557 | boundary_block = map_bh.b_blocknr; |
558 | boundary_bdev = map_bh.b_bdev; |
559 | } |
560 | if (page_block) { |
561 | if (map_bh.b_blocknr != first_block + page_block) |
562 | goto confused; |
563 | } else { |
564 | first_block = map_bh.b_blocknr; |
565 | } |
566 | page_block++; |
567 | boundary = buffer_boundary(bh: &map_bh); |
568 | bdev = map_bh.b_bdev; |
569 | if (block_in_file == last_block) |
570 | break; |
571 | block_in_file++; |
572 | } |
573 | BUG_ON(page_block == 0); |
574 | |
575 | first_unmapped = page_block; |
576 | |
577 | page_is_mapped: |
578 | /* Don't bother writing beyond EOF, truncate will discard the folio */ |
579 | if (folio_pos(folio) >= i_size) |
580 | goto confused; |
581 | length = folio_size(folio); |
582 | if (folio_pos(folio) + length > i_size) { |
583 | /* |
584 | * The page straddles i_size. It must be zeroed out on each |
585 | * and every writepage invocation because it may be mmapped. |
586 | * "A file is mapped in multiples of the page size. For a file |
587 | * that is not a multiple of the page size, the remaining memory |
588 | * is zeroed when mapped, and writes to that region are not |
589 | * written out to the file." |
590 | */ |
591 | length = i_size - folio_pos(folio); |
592 | folio_zero_segment(folio, start: length, xend: folio_size(folio)); |
593 | } |
594 | |
595 | /* |
596 | * This page will go to BIO. Do we need to send this BIO off first? |
597 | */ |
598 | if (bio && mpd->last_block_in_bio != first_block - 1) |
599 | bio = mpage_bio_submit_write(bio); |
600 | |
601 | alloc_new: |
602 | if (bio == NULL) { |
603 | bio = bio_alloc(bdev, BIO_MAX_VECS, |
604 | opf: REQ_OP_WRITE | wbc_to_write_flags(wbc), |
605 | GFP_NOFS); |
606 | bio->bi_iter.bi_sector = first_block << (blkbits - 9); |
607 | wbc_init_bio(wbc, bio); |
608 | bio->bi_write_hint = inode->i_write_hint; |
609 | } |
610 | |
611 | /* |
612 | * Must try to add the page before marking the buffer clean or |
613 | * the confused fail path above (OOM) will be very confused when |
614 | * it finds all bh marked clean (i.e. it will not write anything) |
615 | */ |
616 | wbc_account_cgroup_owner(wbc, page: &folio->page, bytes: folio_size(folio)); |
617 | length = first_unmapped << blkbits; |
618 | if (!bio_add_folio(bio, folio, len: length, off: 0)) { |
619 | bio = mpage_bio_submit_write(bio); |
620 | goto alloc_new; |
621 | } |
622 | |
623 | clean_buffers(folio, first_unmapped); |
624 | |
625 | BUG_ON(folio_test_writeback(folio)); |
626 | folio_start_writeback(folio); |
627 | folio_unlock(folio); |
628 | if (boundary || (first_unmapped != blocks_per_page)) { |
629 | bio = mpage_bio_submit_write(bio); |
630 | if (boundary_block) { |
631 | write_boundary_block(bdev: boundary_bdev, |
632 | bblock: boundary_block, blocksize: 1 << blkbits); |
633 | } |
634 | } else { |
635 | mpd->last_block_in_bio = first_block + blocks_per_page - 1; |
636 | } |
637 | goto out; |
638 | |
639 | confused: |
640 | if (bio) |
641 | bio = mpage_bio_submit_write(bio); |
642 | |
643 | /* |
644 | * The caller has a ref on the inode, so *mapping is stable |
645 | */ |
646 | ret = block_write_full_folio(folio, wbc, get_block: mpd->get_block); |
647 | mapping_set_error(mapping, error: ret); |
648 | out: |
649 | mpd->bio = bio; |
650 | return ret; |
651 | } |
652 | |
653 | /** |
654 | * mpage_writepages - walk the list of dirty pages of the given address space & writepage() all of them |
655 | * @mapping: address space structure to write |
656 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write |
657 | * @get_block: the filesystem's block mapper function. |
658 | * |
659 | * This is a library function, which implements the writepages() |
660 | * address_space_operation. |
661 | */ |
662 | int |
663 | mpage_writepages(struct address_space *mapping, |
664 | struct writeback_control *wbc, get_block_t get_block) |
665 | { |
666 | struct mpage_data mpd = { |
667 | .get_block = get_block, |
668 | }; |
669 | struct blk_plug plug; |
670 | int ret; |
671 | |
672 | blk_start_plug(&plug); |
673 | ret = write_cache_pages(mapping, wbc, writepage: __mpage_writepage, data: &mpd); |
674 | if (mpd.bio) |
675 | mpage_bio_submit_write(bio: mpd.bio); |
676 | blk_finish_plug(&plug); |
677 | return ret; |
678 | } |
679 | EXPORT_SYMBOL(mpage_writepages); |
680 | |