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ae259a9c CH |
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> | |
9a286f0e | 27 | #include <linux/dax.h> |
ae259a9c CH |
28 | #include "internal.h" |
29 | ||
30 | typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len, | |
31 | void *data, struct iomap *iomap); | |
32 | ||
33 | /* | |
34 | * Execute a iomap write on a segment of the mapping that spans a | |
35 | * contiguous range of pages that have identical block mapping state. | |
36 | * | |
37 | * This avoids the need to map pages individually, do individual allocations | |
38 | * for each page and most importantly avoid the need for filesystem specific | |
39 | * locking per page. Instead, all the operations are amortised over the entire | |
40 | * range of pages. It is assumed that the filesystems will lock whatever | |
41 | * resources they require in the iomap_begin call, and release them in the | |
42 | * iomap_end call. | |
43 | */ | |
44 | static loff_t | |
45 | iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags, | |
46 | struct iomap_ops *ops, void *data, iomap_actor_t actor) | |
47 | { | |
48 | struct iomap iomap = { 0 }; | |
49 | loff_t written = 0, ret; | |
50 | ||
51 | /* | |
52 | * Need to map a range from start position for length bytes. This can | |
53 | * span multiple pages - it is only guaranteed to return a range of a | |
54 | * single type of pages (e.g. all into a hole, all mapped or all | |
55 | * unwritten). Failure at this point has nothing to undo. | |
56 | * | |
57 | * If allocation is required for this range, reserve the space now so | |
58 | * that the allocation is guaranteed to succeed later on. Once we copy | |
59 | * the data into the page cache pages, then we cannot fail otherwise we | |
60 | * expose transient stale data. If the reserve fails, we can safely | |
61 | * back out at this point as there is nothing to undo. | |
62 | */ | |
63 | ret = ops->iomap_begin(inode, pos, length, flags, &iomap); | |
64 | if (ret) | |
65 | return ret; | |
66 | if (WARN_ON(iomap.offset > pos)) | |
67 | return -EIO; | |
68 | ||
69 | /* | |
70 | * Cut down the length to the one actually provided by the filesystem, | |
71 | * as it might not be able to give us the whole size that we requested. | |
72 | */ | |
73 | if (iomap.offset + iomap.length < pos + length) | |
74 | length = iomap.offset + iomap.length - pos; | |
75 | ||
76 | /* | |
77 | * Now that we have guaranteed that the space allocation will succeed. | |
78 | * we can do the copy-in page by page without having to worry about | |
79 | * failures exposing transient data. | |
80 | */ | |
81 | written = actor(inode, pos, length, data, &iomap); | |
82 | ||
83 | /* | |
84 | * Now the data has been copied, commit the range we've copied. This | |
85 | * should not fail unless the filesystem has had a fatal error. | |
86 | */ | |
87 | ret = ops->iomap_end(inode, pos, length, written > 0 ? written : 0, | |
88 | flags, &iomap); | |
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 | page = grab_cache_page_write_begin(inode->i_mapping, index, flags); | |
117 | if (!page) | |
118 | return -ENOMEM; | |
119 | ||
120 | status = __block_write_begin_int(page, pos, len, NULL, iomap); | |
121 | if (unlikely(status)) { | |
122 | unlock_page(page); | |
123 | put_page(page); | |
124 | page = NULL; | |
125 | ||
126 | iomap_write_failed(inode, pos, len); | |
127 | } | |
128 | ||
129 | *pagep = page; | |
130 | return status; | |
131 | } | |
132 | ||
133 | static int | |
134 | iomap_write_end(struct inode *inode, loff_t pos, unsigned len, | |
135 | unsigned copied, struct page *page) | |
136 | { | |
137 | int ret; | |
138 | ||
139 | ret = generic_write_end(NULL, inode->i_mapping, pos, len, | |
140 | copied, page, NULL); | |
141 | if (ret < len) | |
142 | iomap_write_failed(inode, pos, len); | |
143 | return ret; | |
144 | } | |
145 | ||
146 | static loff_t | |
147 | iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, | |
148 | struct iomap *iomap) | |
149 | { | |
150 | struct iov_iter *i = data; | |
151 | long status = 0; | |
152 | ssize_t written = 0; | |
153 | unsigned int flags = AOP_FLAG_NOFS; | |
154 | ||
155 | /* | |
156 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
157 | */ | |
158 | if (!iter_is_iovec(i)) | |
159 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
160 | ||
161 | do { | |
162 | struct page *page; | |
163 | unsigned long offset; /* Offset into pagecache page */ | |
164 | unsigned long bytes; /* Bytes to write to page */ | |
165 | size_t copied; /* Bytes copied from user */ | |
166 | ||
167 | offset = (pos & (PAGE_SIZE - 1)); | |
168 | bytes = min_t(unsigned long, PAGE_SIZE - offset, | |
169 | iov_iter_count(i)); | |
170 | again: | |
171 | if (bytes > length) | |
172 | bytes = length; | |
173 | ||
174 | /* | |
175 | * Bring in the user page that we will copy from _first_. | |
176 | * Otherwise there's a nasty deadlock on copying from the | |
177 | * same page as we're writing to, without it being marked | |
178 | * up-to-date. | |
179 | * | |
180 | * Not only is this an optimisation, but it is also required | |
181 | * to check that the address is actually valid, when atomic | |
182 | * usercopies are used, below. | |
183 | */ | |
184 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
185 | status = -EFAULT; | |
186 | break; | |
187 | } | |
188 | ||
189 | status = iomap_write_begin(inode, pos, bytes, flags, &page, | |
190 | iomap); | |
191 | if (unlikely(status)) | |
192 | break; | |
193 | ||
194 | if (mapping_writably_mapped(inode->i_mapping)) | |
195 | flush_dcache_page(page); | |
196 | ||
ae259a9c | 197 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); |
ae259a9c CH |
198 | |
199 | flush_dcache_page(page); | |
ae259a9c CH |
200 | |
201 | status = iomap_write_end(inode, pos, bytes, copied, page); | |
202 | if (unlikely(status < 0)) | |
203 | break; | |
204 | copied = status; | |
205 | ||
206 | cond_resched(); | |
207 | ||
208 | iov_iter_advance(i, copied); | |
209 | if (unlikely(copied == 0)) { | |
210 | /* | |
211 | * If we were unable to copy any data at all, we must | |
212 | * fall back to a single segment length write. | |
213 | * | |
214 | * If we didn't fallback here, we could livelock | |
215 | * because not all segments in the iov can be copied at | |
216 | * once without a pagefault. | |
217 | */ | |
218 | bytes = min_t(unsigned long, PAGE_SIZE - offset, | |
219 | iov_iter_single_seg_count(i)); | |
220 | goto again; | |
221 | } | |
222 | pos += copied; | |
223 | written += copied; | |
224 | length -= copied; | |
225 | ||
226 | balance_dirty_pages_ratelimited(inode->i_mapping); | |
227 | } while (iov_iter_count(i) && length); | |
228 | ||
229 | return written ? written : status; | |
230 | } | |
231 | ||
232 | ssize_t | |
233 | iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter, | |
234 | struct iomap_ops *ops) | |
235 | { | |
236 | struct inode *inode = iocb->ki_filp->f_mapping->host; | |
237 | loff_t pos = iocb->ki_pos, ret = 0, written = 0; | |
238 | ||
239 | while (iov_iter_count(iter)) { | |
240 | ret = iomap_apply(inode, pos, iov_iter_count(iter), | |
241 | IOMAP_WRITE, ops, iter, iomap_write_actor); | |
242 | if (ret <= 0) | |
243 | break; | |
244 | pos += ret; | |
245 | written += ret; | |
246 | } | |
247 | ||
248 | return written ? written : ret; | |
249 | } | |
250 | EXPORT_SYMBOL_GPL(iomap_file_buffered_write); | |
251 | ||
252 | static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, | |
253 | unsigned bytes, struct iomap *iomap) | |
254 | { | |
255 | struct page *page; | |
256 | int status; | |
257 | ||
258 | status = iomap_write_begin(inode, pos, bytes, | |
259 | AOP_FLAG_UNINTERRUPTIBLE | AOP_FLAG_NOFS, &page, iomap); | |
260 | if (status) | |
261 | return status; | |
262 | ||
263 | zero_user(page, offset, bytes); | |
264 | mark_page_accessed(page); | |
265 | ||
266 | return iomap_write_end(inode, pos, bytes, bytes, page); | |
267 | } | |
268 | ||
9a286f0e CH |
269 | static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes, |
270 | struct iomap *iomap) | |
271 | { | |
272 | sector_t sector = iomap->blkno + | |
273 | (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9); | |
274 | ||
275 | return __dax_zero_page_range(iomap->bdev, sector, offset, bytes); | |
276 | } | |
277 | ||
ae259a9c CH |
278 | static loff_t |
279 | iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, | |
280 | void *data, struct iomap *iomap) | |
281 | { | |
282 | bool *did_zero = data; | |
283 | loff_t written = 0; | |
284 | int status; | |
285 | ||
286 | /* already zeroed? we're done. */ | |
287 | if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) | |
288 | return count; | |
289 | ||
290 | do { | |
291 | unsigned offset, bytes; | |
292 | ||
293 | offset = pos & (PAGE_SIZE - 1); /* Within page */ | |
294 | bytes = min_t(unsigned, PAGE_SIZE - offset, count); | |
295 | ||
9a286f0e CH |
296 | if (IS_DAX(inode)) |
297 | status = iomap_dax_zero(pos, offset, bytes, iomap); | |
298 | else | |
299 | status = iomap_zero(inode, pos, offset, bytes, iomap); | |
ae259a9c CH |
300 | if (status < 0) |
301 | return status; | |
302 | ||
303 | pos += bytes; | |
304 | count -= bytes; | |
305 | written += bytes; | |
306 | if (did_zero) | |
307 | *did_zero = true; | |
308 | } while (count > 0); | |
309 | ||
310 | return written; | |
311 | } | |
312 | ||
313 | int | |
314 | iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, | |
315 | struct iomap_ops *ops) | |
316 | { | |
317 | loff_t ret; | |
318 | ||
319 | while (len > 0) { | |
320 | ret = iomap_apply(inode, pos, len, IOMAP_ZERO, | |
321 | ops, did_zero, iomap_zero_range_actor); | |
322 | if (ret <= 0) | |
323 | return ret; | |
324 | ||
325 | pos += ret; | |
326 | len -= ret; | |
327 | } | |
328 | ||
329 | return 0; | |
330 | } | |
331 | EXPORT_SYMBOL_GPL(iomap_zero_range); | |
332 | ||
333 | int | |
334 | iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, | |
335 | struct iomap_ops *ops) | |
336 | { | |
337 | unsigned blocksize = (1 << inode->i_blkbits); | |
338 | unsigned off = pos & (blocksize - 1); | |
339 | ||
340 | /* Block boundary? Nothing to do */ | |
341 | if (!off) | |
342 | return 0; | |
343 | return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops); | |
344 | } | |
345 | EXPORT_SYMBOL_GPL(iomap_truncate_page); | |
346 | ||
347 | static loff_t | |
348 | iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, | |
349 | void *data, struct iomap *iomap) | |
350 | { | |
351 | struct page *page = data; | |
352 | int ret; | |
353 | ||
354 | ret = __block_write_begin_int(page, pos & ~PAGE_MASK, length, | |
355 | NULL, iomap); | |
356 | if (ret) | |
357 | return ret; | |
358 | ||
359 | block_commit_write(page, 0, length); | |
360 | return length; | |
361 | } | |
362 | ||
363 | int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, | |
364 | struct iomap_ops *ops) | |
365 | { | |
366 | struct page *page = vmf->page; | |
367 | struct inode *inode = file_inode(vma->vm_file); | |
368 | unsigned long length; | |
369 | loff_t offset, size; | |
370 | ssize_t ret; | |
371 | ||
372 | lock_page(page); | |
373 | size = i_size_read(inode); | |
374 | if ((page->mapping != inode->i_mapping) || | |
375 | (page_offset(page) > size)) { | |
376 | /* We overload EFAULT to mean page got truncated */ | |
377 | ret = -EFAULT; | |
378 | goto out_unlock; | |
379 | } | |
380 | ||
381 | /* page is wholly or partially inside EOF */ | |
382 | if (((page->index + 1) << PAGE_SHIFT) > size) | |
383 | length = size & ~PAGE_MASK; | |
384 | else | |
385 | length = PAGE_SIZE; | |
386 | ||
387 | offset = page_offset(page); | |
388 | while (length > 0) { | |
389 | ret = iomap_apply(inode, offset, length, IOMAP_WRITE, | |
390 | ops, page, iomap_page_mkwrite_actor); | |
391 | if (unlikely(ret <= 0)) | |
392 | goto out_unlock; | |
393 | offset += ret; | |
394 | length -= ret; | |
395 | } | |
396 | ||
397 | set_page_dirty(page); | |
398 | wait_for_stable_page(page); | |
399 | return 0; | |
400 | out_unlock: | |
401 | unlock_page(page); | |
402 | return ret; | |
403 | } | |
404 | EXPORT_SYMBOL_GPL(iomap_page_mkwrite); | |
8be9f564 CH |
405 | |
406 | struct fiemap_ctx { | |
407 | struct fiemap_extent_info *fi; | |
408 | struct iomap prev; | |
409 | }; | |
410 | ||
411 | static int iomap_to_fiemap(struct fiemap_extent_info *fi, | |
412 | struct iomap *iomap, u32 flags) | |
413 | { | |
414 | switch (iomap->type) { | |
415 | case IOMAP_HOLE: | |
416 | /* skip holes */ | |
417 | return 0; | |
418 | case IOMAP_DELALLOC: | |
419 | flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN; | |
420 | break; | |
421 | case IOMAP_UNWRITTEN: | |
422 | flags |= FIEMAP_EXTENT_UNWRITTEN; | |
423 | break; | |
424 | case IOMAP_MAPPED: | |
425 | break; | |
426 | } | |
427 | ||
428 | return fiemap_fill_next_extent(fi, iomap->offset, | |
429 | iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0, | |
430 | iomap->length, flags | FIEMAP_EXTENT_MERGED); | |
431 | ||
432 | } | |
433 | ||
434 | static loff_t | |
435 | iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, | |
436 | struct iomap *iomap) | |
437 | { | |
438 | struct fiemap_ctx *ctx = data; | |
439 | loff_t ret = length; | |
440 | ||
441 | if (iomap->type == IOMAP_HOLE) | |
442 | return length; | |
443 | ||
444 | ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0); | |
445 | ctx->prev = *iomap; | |
446 | switch (ret) { | |
447 | case 0: /* success */ | |
448 | return length; | |
449 | case 1: /* extent array full */ | |
450 | return 0; | |
451 | default: | |
452 | return ret; | |
453 | } | |
454 | } | |
455 | ||
456 | int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, | |
457 | loff_t start, loff_t len, struct iomap_ops *ops) | |
458 | { | |
459 | struct fiemap_ctx ctx; | |
460 | loff_t ret; | |
461 | ||
462 | memset(&ctx, 0, sizeof(ctx)); | |
463 | ctx.fi = fi; | |
464 | ctx.prev.type = IOMAP_HOLE; | |
465 | ||
466 | ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC); | |
467 | if (ret) | |
468 | return ret; | |
469 | ||
470 | ret = filemap_write_and_wait(inode->i_mapping); | |
471 | if (ret) | |
472 | return ret; | |
473 | ||
474 | while (len > 0) { | |
475 | ret = iomap_apply(inode, start, len, 0, ops, &ctx, | |
476 | iomap_fiemap_actor); | |
477 | if (ret < 0) | |
478 | return ret; | |
479 | if (ret == 0) | |
480 | break; | |
481 | ||
482 | start += ret; | |
483 | len -= ret; | |
484 | } | |
485 | ||
486 | if (ctx.prev.type != IOMAP_HOLE) { | |
487 | ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST); | |
488 | if (ret < 0) | |
489 | return ret; | |
490 | } | |
491 | ||
492 | return 0; | |
493 | } | |
494 | EXPORT_SYMBOL_GPL(iomap_fiemap); |