blob: 814ae8f9587dd52e6c4d190c5f77fa65fc51344b [file] [log] [blame]
Christoph Hellwigae259a92016-06-21 09:23:11 +10001/*
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>
Christoph Hellwig9a286f02016-06-21 09:31:39 +100027#include <linux/dax.h>
Christoph Hellwigae259a92016-06-21 09:23:11 +100028#include "internal.h"
29
Christoph Hellwigae259a92016-06-21 09:23:11 +100030/*
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 */
Christoph Hellwigbefb5032016-09-19 11:24:49 +100041loff_t
Christoph Hellwigae259a92016-06-21 09:23:11 +100042iomap_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 */
Christoph Hellwigf20ac7a2016-08-17 08:42:34 +100084 if (ops->iomap_end) {
85 ret = ops->iomap_end(inode, pos, length,
86 written > 0 ? written : 0,
87 flags, &iomap);
88 }
Christoph Hellwigae259a92016-06-21 09:23:11 +100089
90 return written ? written : ret;
91}
92
93static void
94iomap_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
106static int
107iomap_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
Michal Hocko72cd6042017-02-03 13:13:26 -0800116 if (fatal_signal_pending(current))
117 return -EINTR;
118
Christoph Hellwigae259a92016-06-21 09:23:11 +1000119 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
136static int
137iomap_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
149static loff_t
150iomap_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));
173again:
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
Christoph Hellwigae259a92016-06-21 09:23:11 +1000200 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
Christoph Hellwigae259a92016-06-21 09:23:11 +1000201
202 flush_dcache_page(page);
Christoph Hellwigae259a92016-06-21 09:23:11 +1000203
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
235ssize_t
236iomap_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}
253EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
254
Christoph Hellwig5f4e5752016-09-19 10:12:45 +1000255static 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
271static loff_t
272iomap_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(unsigned long, 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
318int
319iomap_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}
335EXPORT_SYMBOL_GPL(iomap_file_dirty);
336
Christoph Hellwigae259a92016-06-21 09:23:11 +1000337static 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
Christoph Hellwig9a286f02016-06-21 09:31:39 +1000354static 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
Christoph Hellwigae259a92016-06-21 09:23:11 +1000363static loff_t
364iomap_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(unsigned, PAGE_SIZE - offset, count);
380
Christoph Hellwig9a286f02016-06-21 09:31:39 +1000381 if (IS_DAX(inode))
382 status = iomap_dax_zero(pos, offset, bytes, iomap);
383 else
384 status = iomap_zero(inode, pos, offset, bytes, iomap);
Christoph Hellwigae259a92016-06-21 09:23:11 +1000385 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
398int
399iomap_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}
416EXPORT_SYMBOL_GPL(iomap_zero_range);
417
418int
419iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
420 struct iomap_ops *ops)
421{
422 unsigned blocksize = (1 << inode->i_blkbits);
423 unsigned 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}
430EXPORT_SYMBOL_GPL(iomap_truncate_page);
431
432static loff_t
433iomap_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
Jan Karac663e292016-10-24 14:20:25 +1100439 ret = __block_write_begin_int(page, pos, length, NULL, iomap);
Christoph Hellwigae259a92016-06-21 09:23:11 +1000440 if (ret)
441 return ret;
442
443 block_commit_write(page, 0, length);
444 return length;
445}
446
447int 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;
484out_unlock:
485 unlock_page(page);
486 return ret;
487}
488EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
Christoph Hellwig8be9f562016-06-21 09:38:45 +1000489
490struct fiemap_ctx {
491 struct fiemap_extent_info *fi;
492 struct iomap prev;
493};
494
495static 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
Christoph Hellwig17de0a92016-08-29 11:33:58 +1000512 if (iomap->flags & IOMAP_F_MERGED)
513 flags |= FIEMAP_EXTENT_MERGED;
Darrick J. Wonge43c4602016-09-19 10:13:02 +1000514 if (iomap->flags & IOMAP_F_SHARED)
515 flags |= FIEMAP_EXTENT_SHARED;
Christoph Hellwig17de0a92016-08-29 11:33:58 +1000516
Christoph Hellwig8be9f562016-06-21 09:38:45 +1000517 return fiemap_fill_next_extent(fi, iomap->offset,
518 iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
Christoph Hellwig17de0a92016-08-29 11:33:58 +1000519 iomap->length, flags);
Christoph Hellwig8be9f562016-06-21 09:38:45 +1000520
521}
522
523static loff_t
524iomap_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
545int 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
Dave Chinner8896b8f2016-08-17 08:41:10 +1000559 if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
560 ret = filemap_write_and_wait(inode->i_mapping);
561 if (ret)
562 return ret;
563 }
Christoph Hellwig8be9f562016-06-21 09:38:45 +1000564
565 while (len > 0) {
Christoph Hellwigd33fd772016-10-20 15:51:28 +1100566 ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
Christoph Hellwig8be9f562016-06-21 09:38:45 +1000567 iomap_fiemap_actor);
Dave Chinnerac2dc052016-08-17 08:41:34 +1000568 /* inode with no (attribute) mapping will give ENOENT */
569 if (ret == -ENOENT)
570 break;
Christoph Hellwig8be9f562016-06-21 09:38:45 +1000571 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}
588EXPORT_SYMBOL_GPL(iomap_fiemap);