blob: a49db8806a3aafd8fed12b29fa45277b9d6a5416
1 | /* |
2 | * Copyright (C) 2010 Red Hat, Inc. |
3 | * Copyright (c) 2016 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/mm.h> |
21 | #include <linux/swap.h> |
22 | #include <linux/pagemap.h> |
23 | #include <linux/file.h> |
24 | #include <linux/uio.h> |
25 | #include <linux/backing-dev.h> |
26 | #include <linux/buffer_head.h> |
27 | #include <linux/dax.h> |
28 | #include "internal.h" |
29 | |
30 | /* |
31 | * Execute a iomap write on a segment of the mapping that spans a |
32 | * contiguous range of pages that have identical block mapping state. |
33 | * |
34 | * This avoids the need to map pages individually, do individual allocations |
35 | * for each page and most importantly avoid the need for filesystem specific |
36 | * locking per page. Instead, all the operations are amortised over the entire |
37 | * range of pages. It is assumed that the filesystems will lock whatever |
38 | * resources they require in the iomap_begin call, and release them in the |
39 | * iomap_end call. |
40 | */ |
41 | loff_t |
42 | iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags, |
43 | struct iomap_ops *ops, void *data, iomap_actor_t actor) |
44 | { |
45 | struct iomap iomap = { 0 }; |
46 | loff_t written = 0, ret; |
47 | |
48 | /* |
49 | * Need to map a range from start position for length bytes. This can |
50 | * span multiple pages - it is only guaranteed to return a range of a |
51 | * single type of pages (e.g. all into a hole, all mapped or all |
52 | * unwritten). Failure at this point has nothing to undo. |
53 | * |
54 | * If allocation is required for this range, reserve the space now so |
55 | * that the allocation is guaranteed to succeed later on. Once we copy |
56 | * the data into the page cache pages, then we cannot fail otherwise we |
57 | * expose transient stale data. If the reserve fails, we can safely |
58 | * back out at this point as there is nothing to undo. |
59 | */ |
60 | ret = ops->iomap_begin(inode, pos, length, flags, &iomap); |
61 | if (ret) |
62 | return ret; |
63 | if (WARN_ON(iomap.offset > pos)) |
64 | return -EIO; |
65 | |
66 | /* |
67 | * Cut down the length to the one actually provided by the filesystem, |
68 | * as it might not be able to give us the whole size that we requested. |
69 | */ |
70 | if (iomap.offset + iomap.length < pos + length) |
71 | length = iomap.offset + iomap.length - pos; |
72 | |
73 | /* |
74 | * Now that we have guaranteed that the space allocation will succeed. |
75 | * we can do the copy-in page by page without having to worry about |
76 | * failures exposing transient data. |
77 | */ |
78 | written = actor(inode, pos, length, data, &iomap); |
79 | |
80 | /* |
81 | * Now the data has been copied, commit the range we've copied. This |
82 | * should not fail unless the filesystem has had a fatal error. |
83 | */ |
84 | if (ops->iomap_end) { |
85 | ret = ops->iomap_end(inode, pos, length, |
86 | written > 0 ? written : 0, |
87 | flags, &iomap); |
88 | } |
89 | |
90 | return written ? written : ret; |
91 | } |
92 | |
93 | static void |
94 | iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) |
95 | { |
96 | loff_t i_size = i_size_read(inode); |
97 | |
98 | /* |
99 | * Only truncate newly allocated pages beyoned EOF, even if the |
100 | * write started inside the existing inode size. |
101 | */ |
102 | if (pos + len > i_size) |
103 | truncate_pagecache_range(inode, max(pos, i_size), pos + len); |
104 | } |
105 | |
106 | static int |
107 | iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, |
108 | struct page **pagep, struct iomap *iomap) |
109 | { |
110 | pgoff_t index = pos >> PAGE_SHIFT; |
111 | struct page *page; |
112 | int status = 0; |
113 | |
114 | BUG_ON(pos + len > iomap->offset + iomap->length); |
115 | |
116 | if (fatal_signal_pending(current)) |
117 | return -EINTR; |
118 | |
119 | page = grab_cache_page_write_begin(inode->i_mapping, index, flags); |
120 | if (!page) |
121 | return -ENOMEM; |
122 | |
123 | status = __block_write_begin_int(page, pos, len, NULL, iomap); |
124 | if (unlikely(status)) { |
125 | unlock_page(page); |
126 | put_page(page); |
127 | page = NULL; |
128 | |
129 | iomap_write_failed(inode, pos, len); |
130 | } |
131 | |
132 | *pagep = page; |
133 | return status; |
134 | } |
135 | |
136 | static int |
137 | iomap_write_end(struct inode *inode, loff_t pos, unsigned len, |
138 | unsigned copied, struct page *page) |
139 | { |
140 | int ret; |
141 | |
142 | ret = generic_write_end(NULL, inode->i_mapping, pos, len, |
143 | copied, page, NULL); |
144 | if (ret < len) |
145 | iomap_write_failed(inode, pos, len); |
146 | return ret; |
147 | } |
148 | |
149 | static loff_t |
150 | iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, |
151 | struct iomap *iomap) |
152 | { |
153 | struct iov_iter *i = data; |
154 | long status = 0; |
155 | ssize_t written = 0; |
156 | unsigned int flags = AOP_FLAG_NOFS; |
157 | |
158 | /* |
159 | * Copies from kernel address space cannot fail (NFSD is a big user). |
160 | */ |
161 | if (!iter_is_iovec(i)) |
162 | flags |= AOP_FLAG_UNINTERRUPTIBLE; |
163 | |
164 | do { |
165 | struct page *page; |
166 | unsigned long offset; /* Offset into pagecache page */ |
167 | unsigned long bytes; /* Bytes to write to page */ |
168 | size_t copied; /* Bytes copied from user */ |
169 | |
170 | offset = (pos & (PAGE_SIZE - 1)); |
171 | bytes = min_t(unsigned long, PAGE_SIZE - offset, |
172 | iov_iter_count(i)); |
173 | again: |
174 | if (bytes > length) |
175 | bytes = length; |
176 | |
177 | /* |
178 | * Bring in the user page that we will copy from _first_. |
179 | * Otherwise there's a nasty deadlock on copying from the |
180 | * same page as we're writing to, without it being marked |
181 | * up-to-date. |
182 | * |
183 | * Not only is this an optimisation, but it is also required |
184 | * to check that the address is actually valid, when atomic |
185 | * usercopies are used, below. |
186 | */ |
187 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { |
188 | status = -EFAULT; |
189 | break; |
190 | } |
191 | |
192 | status = iomap_write_begin(inode, pos, bytes, flags, &page, |
193 | iomap); |
194 | if (unlikely(status)) |
195 | break; |
196 | |
197 | if (mapping_writably_mapped(inode->i_mapping)) |
198 | flush_dcache_page(page); |
199 | |
200 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); |
201 | |
202 | flush_dcache_page(page); |
203 | |
204 | status = iomap_write_end(inode, pos, bytes, copied, page); |
205 | if (unlikely(status < 0)) |
206 | break; |
207 | copied = status; |
208 | |
209 | cond_resched(); |
210 | |
211 | iov_iter_advance(i, copied); |
212 | if (unlikely(copied == 0)) { |
213 | /* |
214 | * If we were unable to copy any data at all, we must |
215 | * fall back to a single segment length write. |
216 | * |
217 | * If we didn't fallback here, we could livelock |
218 | * because not all segments in the iov can be copied at |
219 | * once without a pagefault. |
220 | */ |
221 | bytes = min_t(unsigned long, PAGE_SIZE - offset, |
222 | iov_iter_single_seg_count(i)); |
223 | goto again; |
224 | } |
225 | pos += copied; |
226 | written += copied; |
227 | length -= copied; |
228 | |
229 | balance_dirty_pages_ratelimited(inode->i_mapping); |
230 | } while (iov_iter_count(i) && length); |
231 | |
232 | return written ? written : status; |
233 | } |
234 | |
235 | ssize_t |
236 | iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter, |
237 | struct iomap_ops *ops) |
238 | { |
239 | struct inode *inode = iocb->ki_filp->f_mapping->host; |
240 | loff_t pos = iocb->ki_pos, ret = 0, written = 0; |
241 | |
242 | while (iov_iter_count(iter)) { |
243 | ret = iomap_apply(inode, pos, iov_iter_count(iter), |
244 | IOMAP_WRITE, ops, iter, iomap_write_actor); |
245 | if (ret <= 0) |
246 | break; |
247 | pos += ret; |
248 | written += ret; |
249 | } |
250 | |
251 | return written ? written : ret; |
252 | } |
253 | EXPORT_SYMBOL_GPL(iomap_file_buffered_write); |
254 | |
255 | static struct page * |
256 | __iomap_read_page(struct inode *inode, loff_t offset) |
257 | { |
258 | struct address_space *mapping = inode->i_mapping; |
259 | struct page *page; |
260 | |
261 | page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL); |
262 | if (IS_ERR(page)) |
263 | return page; |
264 | if (!PageUptodate(page)) { |
265 | put_page(page); |
266 | return ERR_PTR(-EIO); |
267 | } |
268 | return page; |
269 | } |
270 | |
271 | static loff_t |
272 | iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data, |
273 | struct iomap *iomap) |
274 | { |
275 | long status = 0; |
276 | ssize_t written = 0; |
277 | |
278 | do { |
279 | struct page *page, *rpage; |
280 | unsigned long offset; /* Offset into pagecache page */ |
281 | unsigned long bytes; /* Bytes to write to page */ |
282 | |
283 | offset = (pos & (PAGE_SIZE - 1)); |
284 | bytes = min_t(loff_t, PAGE_SIZE - offset, length); |
285 | |
286 | rpage = __iomap_read_page(inode, pos); |
287 | if (IS_ERR(rpage)) |
288 | return PTR_ERR(rpage); |
289 | |
290 | status = iomap_write_begin(inode, pos, bytes, |
291 | AOP_FLAG_NOFS | AOP_FLAG_UNINTERRUPTIBLE, |
292 | &page, iomap); |
293 | put_page(rpage); |
294 | if (unlikely(status)) |
295 | return status; |
296 | |
297 | WARN_ON_ONCE(!PageUptodate(page)); |
298 | |
299 | status = iomap_write_end(inode, pos, bytes, bytes, page); |
300 | if (unlikely(status <= 0)) { |
301 | if (WARN_ON_ONCE(status == 0)) |
302 | return -EIO; |
303 | return status; |
304 | } |
305 | |
306 | cond_resched(); |
307 | |
308 | pos += status; |
309 | written += status; |
310 | length -= status; |
311 | |
312 | balance_dirty_pages_ratelimited(inode->i_mapping); |
313 | } while (length); |
314 | |
315 | return written; |
316 | } |
317 | |
318 | int |
319 | iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len, |
320 | struct iomap_ops *ops) |
321 | { |
322 | loff_t ret; |
323 | |
324 | while (len) { |
325 | ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL, |
326 | iomap_dirty_actor); |
327 | if (ret <= 0) |
328 | return ret; |
329 | pos += ret; |
330 | len -= ret; |
331 | } |
332 | |
333 | return 0; |
334 | } |
335 | EXPORT_SYMBOL_GPL(iomap_file_dirty); |
336 | |
337 | static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, |
338 | unsigned bytes, struct iomap *iomap) |
339 | { |
340 | struct page *page; |
341 | int status; |
342 | |
343 | status = iomap_write_begin(inode, pos, bytes, |
344 | AOP_FLAG_UNINTERRUPTIBLE | AOP_FLAG_NOFS, &page, iomap); |
345 | if (status) |
346 | return status; |
347 | |
348 | zero_user(page, offset, bytes); |
349 | mark_page_accessed(page); |
350 | |
351 | return iomap_write_end(inode, pos, bytes, bytes, page); |
352 | } |
353 | |
354 | static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes, |
355 | struct iomap *iomap) |
356 | { |
357 | sector_t sector = iomap->blkno + |
358 | (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9); |
359 | |
360 | return __dax_zero_page_range(iomap->bdev, sector, offset, bytes); |
361 | } |
362 | |
363 | static loff_t |
364 | iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, |
365 | void *data, struct iomap *iomap) |
366 | { |
367 | bool *did_zero = data; |
368 | loff_t written = 0; |
369 | int status; |
370 | |
371 | /* already zeroed? we're done. */ |
372 | if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) |
373 | return count; |
374 | |
375 | do { |
376 | unsigned offset, bytes; |
377 | |
378 | offset = pos & (PAGE_SIZE - 1); /* Within page */ |
379 | bytes = min_t(loff_t, PAGE_SIZE - offset, count); |
380 | |
381 | if (IS_DAX(inode)) |
382 | status = iomap_dax_zero(pos, offset, bytes, iomap); |
383 | else |
384 | status = iomap_zero(inode, pos, offset, bytes, iomap); |
385 | if (status < 0) |
386 | return status; |
387 | |
388 | pos += bytes; |
389 | count -= bytes; |
390 | written += bytes; |
391 | if (did_zero) |
392 | *did_zero = true; |
393 | } while (count > 0); |
394 | |
395 | return written; |
396 | } |
397 | |
398 | int |
399 | iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, |
400 | struct iomap_ops *ops) |
401 | { |
402 | loff_t ret; |
403 | |
404 | while (len > 0) { |
405 | ret = iomap_apply(inode, pos, len, IOMAP_ZERO, |
406 | ops, did_zero, iomap_zero_range_actor); |
407 | if (ret <= 0) |
408 | return ret; |
409 | |
410 | pos += ret; |
411 | len -= ret; |
412 | } |
413 | |
414 | return 0; |
415 | } |
416 | EXPORT_SYMBOL_GPL(iomap_zero_range); |
417 | |
418 | int |
419 | iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, |
420 | struct iomap_ops *ops) |
421 | { |
422 | unsigned int blocksize = i_blocksize(inode); |
423 | unsigned int off = pos & (blocksize - 1); |
424 | |
425 | /* Block boundary? Nothing to do */ |
426 | if (!off) |
427 | return 0; |
428 | return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops); |
429 | } |
430 | EXPORT_SYMBOL_GPL(iomap_truncate_page); |
431 | |
432 | static loff_t |
433 | iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, |
434 | void *data, struct iomap *iomap) |
435 | { |
436 | struct page *page = data; |
437 | int ret; |
438 | |
439 | ret = __block_write_begin_int(page, pos, length, NULL, iomap); |
440 | if (ret) |
441 | return ret; |
442 | |
443 | block_commit_write(page, 0, length); |
444 | return length; |
445 | } |
446 | |
447 | int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
448 | struct iomap_ops *ops) |
449 | { |
450 | struct page *page = vmf->page; |
451 | struct inode *inode = file_inode(vma->vm_file); |
452 | unsigned long length; |
453 | loff_t offset, size; |
454 | ssize_t ret; |
455 | |
456 | lock_page(page); |
457 | size = i_size_read(inode); |
458 | if ((page->mapping != inode->i_mapping) || |
459 | (page_offset(page) > size)) { |
460 | /* We overload EFAULT to mean page got truncated */ |
461 | ret = -EFAULT; |
462 | goto out_unlock; |
463 | } |
464 | |
465 | /* page is wholly or partially inside EOF */ |
466 | if (((page->index + 1) << PAGE_SHIFT) > size) |
467 | length = size & ~PAGE_MASK; |
468 | else |
469 | length = PAGE_SIZE; |
470 | |
471 | offset = page_offset(page); |
472 | while (length > 0) { |
473 | ret = iomap_apply(inode, offset, length, IOMAP_WRITE, |
474 | ops, page, iomap_page_mkwrite_actor); |
475 | if (unlikely(ret <= 0)) |
476 | goto out_unlock; |
477 | offset += ret; |
478 | length -= ret; |
479 | } |
480 | |
481 | set_page_dirty(page); |
482 | wait_for_stable_page(page); |
483 | return 0; |
484 | out_unlock: |
485 | unlock_page(page); |
486 | return ret; |
487 | } |
488 | EXPORT_SYMBOL_GPL(iomap_page_mkwrite); |
489 | |
490 | struct fiemap_ctx { |
491 | struct fiemap_extent_info *fi; |
492 | struct iomap prev; |
493 | }; |
494 | |
495 | static int iomap_to_fiemap(struct fiemap_extent_info *fi, |
496 | struct iomap *iomap, u32 flags) |
497 | { |
498 | switch (iomap->type) { |
499 | case IOMAP_HOLE: |
500 | /* skip holes */ |
501 | return 0; |
502 | case IOMAP_DELALLOC: |
503 | flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN; |
504 | break; |
505 | case IOMAP_UNWRITTEN: |
506 | flags |= FIEMAP_EXTENT_UNWRITTEN; |
507 | break; |
508 | case IOMAP_MAPPED: |
509 | break; |
510 | } |
511 | |
512 | if (iomap->flags & IOMAP_F_MERGED) |
513 | flags |= FIEMAP_EXTENT_MERGED; |
514 | if (iomap->flags & IOMAP_F_SHARED) |
515 | flags |= FIEMAP_EXTENT_SHARED; |
516 | |
517 | return fiemap_fill_next_extent(fi, iomap->offset, |
518 | iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0, |
519 | iomap->length, flags); |
520 | |
521 | } |
522 | |
523 | static loff_t |
524 | iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, |
525 | struct iomap *iomap) |
526 | { |
527 | struct fiemap_ctx *ctx = data; |
528 | loff_t ret = length; |
529 | |
530 | if (iomap->type == IOMAP_HOLE) |
531 | return length; |
532 | |
533 | ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0); |
534 | ctx->prev = *iomap; |
535 | switch (ret) { |
536 | case 0: /* success */ |
537 | return length; |
538 | case 1: /* extent array full */ |
539 | return 0; |
540 | default: |
541 | return ret; |
542 | } |
543 | } |
544 | |
545 | int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, |
546 | loff_t start, loff_t len, struct iomap_ops *ops) |
547 | { |
548 | struct fiemap_ctx ctx; |
549 | loff_t ret; |
550 | |
551 | memset(&ctx, 0, sizeof(ctx)); |
552 | ctx.fi = fi; |
553 | ctx.prev.type = IOMAP_HOLE; |
554 | |
555 | ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC); |
556 | if (ret) |
557 | return ret; |
558 | |
559 | if (fi->fi_flags & FIEMAP_FLAG_SYNC) { |
560 | ret = filemap_write_and_wait(inode->i_mapping); |
561 | if (ret) |
562 | return ret; |
563 | } |
564 | |
565 | while (len > 0) { |
566 | ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx, |
567 | iomap_fiemap_actor); |
568 | /* inode with no (attribute) mapping will give ENOENT */ |
569 | if (ret == -ENOENT) |
570 | break; |
571 | if (ret < 0) |
572 | return ret; |
573 | if (ret == 0) |
574 | break; |
575 | |
576 | start += ret; |
577 | len -= ret; |
578 | } |
579 | |
580 | if (ctx.prev.type != IOMAP_HOLE) { |
581 | ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST); |
582 | if (ret < 0) |
583 | return ret; |
584 | } |
585 | |
586 | return 0; |
587 | } |
588 | EXPORT_SYMBOL_GPL(iomap_fiemap); |
589 |