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d475c634 MW |
1 | /* |
2 | * fs/dax.c - Direct Access filesystem code | |
3 | * Copyright (c) 2013-2014 Intel Corporation | |
4 | * Author: Matthew Wilcox <matthew.r.wilcox@intel.com> | |
5 | * Author: Ross Zwisler <ross.zwisler@linux.intel.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify it | |
8 | * under the terms and conditions of the GNU General Public License, | |
9 | * version 2, as published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope it will be useful, but WITHOUT | |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
14 | * more details. | |
15 | */ | |
16 | ||
17 | #include <linux/atomic.h> | |
18 | #include <linux/blkdev.h> | |
19 | #include <linux/buffer_head.h> | |
d77e92e2 | 20 | #include <linux/dax.h> |
d475c634 MW |
21 | #include <linux/fs.h> |
22 | #include <linux/genhd.h> | |
f7ca90b1 MW |
23 | #include <linux/highmem.h> |
24 | #include <linux/memcontrol.h> | |
25 | #include <linux/mm.h> | |
d475c634 | 26 | #include <linux/mutex.h> |
9973c98e | 27 | #include <linux/pagevec.h> |
2765cfbb | 28 | #include <linux/pmem.h> |
289c6aed | 29 | #include <linux/sched.h> |
d475c634 | 30 | #include <linux/uio.h> |
f7ca90b1 | 31 | #include <linux/vmstat.h> |
34c0fd54 | 32 | #include <linux/pfn_t.h> |
0e749e54 | 33 | #include <linux/sizes.h> |
d475c634 | 34 | |
e4b27491 N |
35 | #define RADIX_DAX_MASK 0xf |
36 | #define RADIX_DAX_SHIFT 4 | |
37 | #define RADIX_DAX_PTE (0x4 | RADIX_TREE_EXCEPTIONAL_ENTRY) | |
38 | #define RADIX_DAX_PMD (0x8 | RADIX_TREE_EXCEPTIONAL_ENTRY) | |
39 | #define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_MASK) | |
40 | #define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT)) | |
41 | #define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \ | |
42 | RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE))) | |
43 | ||
b2e0d162 DW |
44 | static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax) |
45 | { | |
46 | struct request_queue *q = bdev->bd_queue; | |
47 | long rc = -EIO; | |
48 | ||
49 | dax->addr = (void __pmem *) ERR_PTR(-EIO); | |
50 | if (blk_queue_enter(q, true) != 0) | |
51 | return rc; | |
52 | ||
53 | rc = bdev_direct_access(bdev, dax); | |
54 | if (rc < 0) { | |
55 | dax->addr = (void __pmem *) ERR_PTR(rc); | |
56 | blk_queue_exit(q); | |
57 | return rc; | |
58 | } | |
59 | return rc; | |
60 | } | |
61 | ||
62 | static void dax_unmap_atomic(struct block_device *bdev, | |
63 | const struct blk_dax_ctl *dax) | |
64 | { | |
65 | if (IS_ERR(dax->addr)) | |
66 | return; | |
67 | blk_queue_exit(bdev->bd_queue); | |
68 | } | |
69 | ||
d1a5f2b4 DW |
70 | struct page *read_dax_sector(struct block_device *bdev, sector_t n) |
71 | { | |
72 | struct page *page = alloc_pages(GFP_KERNEL, 0); | |
73 | struct blk_dax_ctl dax = { | |
74 | .size = PAGE_SIZE, | |
75 | .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), | |
76 | }; | |
77 | long rc; | |
78 | ||
79 | if (!page) | |
80 | return ERR_PTR(-ENOMEM); | |
81 | ||
82 | rc = dax_map_atomic(bdev, &dax); | |
83 | if (rc < 0) | |
84 | return ERR_PTR(rc); | |
85 | memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE); | |
86 | dax_unmap_atomic(bdev, &dax); | |
87 | return page; | |
88 | } | |
89 | ||
d475c634 MW |
90 | static bool buffer_written(struct buffer_head *bh) |
91 | { | |
92 | return buffer_mapped(bh) && !buffer_unwritten(bh); | |
93 | } | |
94 | ||
95 | /* | |
96 | * When ext4 encounters a hole, it returns without modifying the buffer_head | |
97 | * which means that we can't trust b_size. To cope with this, we set b_state | |
98 | * to 0 before calling get_block and, if any bit is set, we know we can trust | |
99 | * b_size. Unfortunate, really, since ext4 knows precisely how long a hole is | |
100 | * and would save us time calling get_block repeatedly. | |
101 | */ | |
102 | static bool buffer_size_valid(struct buffer_head *bh) | |
103 | { | |
104 | return bh->b_state != 0; | |
105 | } | |
106 | ||
b2e0d162 DW |
107 | |
108 | static sector_t to_sector(const struct buffer_head *bh, | |
109 | const struct inode *inode) | |
110 | { | |
111 | sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9); | |
112 | ||
113 | return sector; | |
114 | } | |
115 | ||
a95cd631 OS |
116 | static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, |
117 | loff_t start, loff_t end, get_block_t get_block, | |
118 | struct buffer_head *bh) | |
d475c634 | 119 | { |
b2e0d162 DW |
120 | loff_t pos = start, max = start, bh_max = start; |
121 | bool hole = false, need_wmb = false; | |
122 | struct block_device *bdev = NULL; | |
123 | int rw = iov_iter_rw(iter), rc; | |
124 | long map_len = 0; | |
125 | struct blk_dax_ctl dax = { | |
126 | .addr = (void __pmem *) ERR_PTR(-EIO), | |
127 | }; | |
069c77bc JK |
128 | unsigned blkbits = inode->i_blkbits; |
129 | sector_t file_blks = (i_size_read(inode) + (1 << blkbits) - 1) | |
130 | >> blkbits; | |
b2e0d162 DW |
131 | |
132 | if (rw == READ) | |
d475c634 MW |
133 | end = min(end, i_size_read(inode)); |
134 | ||
135 | while (pos < end) { | |
2765cfbb | 136 | size_t len; |
d475c634 | 137 | if (pos == max) { |
e94f5a22 JM |
138 | long page = pos >> PAGE_SHIFT; |
139 | sector_t block = page << (PAGE_SHIFT - blkbits); | |
d475c634 MW |
140 | unsigned first = pos - (block << blkbits); |
141 | long size; | |
142 | ||
143 | if (pos == bh_max) { | |
144 | bh->b_size = PAGE_ALIGN(end - pos); | |
145 | bh->b_state = 0; | |
b2e0d162 DW |
146 | rc = get_block(inode, block, bh, rw == WRITE); |
147 | if (rc) | |
d475c634 MW |
148 | break; |
149 | if (!buffer_size_valid(bh)) | |
150 | bh->b_size = 1 << blkbits; | |
151 | bh_max = pos - first + bh->b_size; | |
b2e0d162 | 152 | bdev = bh->b_bdev; |
069c77bc JK |
153 | /* |
154 | * We allow uninitialized buffers for writes | |
155 | * beyond EOF as those cannot race with faults | |
156 | */ | |
157 | WARN_ON_ONCE( | |
158 | (buffer_new(bh) && block < file_blks) || | |
159 | (rw == WRITE && buffer_unwritten(bh))); | |
d475c634 MW |
160 | } else { |
161 | unsigned done = bh->b_size - | |
162 | (bh_max - (pos - first)); | |
163 | bh->b_blocknr += done >> blkbits; | |
164 | bh->b_size -= done; | |
165 | } | |
166 | ||
b2e0d162 | 167 | hole = rw == READ && !buffer_written(bh); |
d475c634 | 168 | if (hole) { |
d475c634 MW |
169 | size = bh->b_size - first; |
170 | } else { | |
b2e0d162 DW |
171 | dax_unmap_atomic(bdev, &dax); |
172 | dax.sector = to_sector(bh, inode); | |
173 | dax.size = bh->b_size; | |
174 | map_len = dax_map_atomic(bdev, &dax); | |
175 | if (map_len < 0) { | |
176 | rc = map_len; | |
d475c634 | 177 | break; |
b2e0d162 | 178 | } |
b2e0d162 DW |
179 | dax.addr += first; |
180 | size = map_len - first; | |
d475c634 MW |
181 | } |
182 | max = min(pos + size, end); | |
183 | } | |
184 | ||
2765cfbb | 185 | if (iov_iter_rw(iter) == WRITE) { |
b2e0d162 | 186 | len = copy_from_iter_pmem(dax.addr, max - pos, iter); |
2765cfbb RZ |
187 | need_wmb = true; |
188 | } else if (!hole) | |
b2e0d162 | 189 | len = copy_to_iter((void __force *) dax.addr, max - pos, |
e2e05394 | 190 | iter); |
d475c634 MW |
191 | else |
192 | len = iov_iter_zero(max - pos, iter); | |
193 | ||
cadfbb6e | 194 | if (!len) { |
b2e0d162 | 195 | rc = -EFAULT; |
d475c634 | 196 | break; |
cadfbb6e | 197 | } |
d475c634 MW |
198 | |
199 | pos += len; | |
b2e0d162 DW |
200 | if (!IS_ERR(dax.addr)) |
201 | dax.addr += len; | |
d475c634 MW |
202 | } |
203 | ||
2765cfbb RZ |
204 | if (need_wmb) |
205 | wmb_pmem(); | |
b2e0d162 | 206 | dax_unmap_atomic(bdev, &dax); |
2765cfbb | 207 | |
b2e0d162 | 208 | return (pos == start) ? rc : pos - start; |
d475c634 MW |
209 | } |
210 | ||
211 | /** | |
212 | * dax_do_io - Perform I/O to a DAX file | |
d475c634 MW |
213 | * @iocb: The control block for this I/O |
214 | * @inode: The file which the I/O is directed at | |
215 | * @iter: The addresses to do I/O from or to | |
216 | * @pos: The file offset where the I/O starts | |
217 | * @get_block: The filesystem method used to translate file offsets to blocks | |
218 | * @end_io: A filesystem callback for I/O completion | |
219 | * @flags: See below | |
220 | * | |
221 | * This function uses the same locking scheme as do_blockdev_direct_IO: | |
222 | * If @flags has DIO_LOCKING set, we assume that the i_mutex is held by the | |
223 | * caller for writes. For reads, we take and release the i_mutex ourselves. | |
224 | * If DIO_LOCKING is not set, the filesystem takes care of its own locking. | |
225 | * As with do_blockdev_direct_IO(), we increment i_dio_count while the I/O | |
226 | * is in progress. | |
227 | */ | |
a95cd631 OS |
228 | ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, |
229 | struct iov_iter *iter, loff_t pos, get_block_t get_block, | |
230 | dio_iodone_t end_io, int flags) | |
d475c634 MW |
231 | { |
232 | struct buffer_head bh; | |
233 | ssize_t retval = -EINVAL; | |
234 | loff_t end = pos + iov_iter_count(iter); | |
235 | ||
236 | memset(&bh, 0, sizeof(bh)); | |
eab95db6 | 237 | bh.b_bdev = inode->i_sb->s_bdev; |
d475c634 | 238 | |
c3d98e39 | 239 | if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) |
5955102c | 240 | inode_lock(inode); |
d475c634 MW |
241 | |
242 | /* Protects against truncate */ | |
bbab37dd MW |
243 | if (!(flags & DIO_SKIP_DIO_COUNT)) |
244 | inode_dio_begin(inode); | |
d475c634 | 245 | |
a95cd631 | 246 | retval = dax_io(inode, iter, pos, end, get_block, &bh); |
d475c634 | 247 | |
a95cd631 | 248 | if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) |
5955102c | 249 | inode_unlock(inode); |
d475c634 | 250 | |
187372a3 CH |
251 | if (end_io) { |
252 | int err; | |
253 | ||
254 | err = end_io(iocb, pos, retval, bh.b_private); | |
255 | if (err) | |
256 | retval = err; | |
257 | } | |
d475c634 | 258 | |
bbab37dd MW |
259 | if (!(flags & DIO_SKIP_DIO_COUNT)) |
260 | inode_dio_end(inode); | |
d475c634 MW |
261 | return retval; |
262 | } | |
263 | EXPORT_SYMBOL_GPL(dax_do_io); | |
f7ca90b1 MW |
264 | |
265 | /* | |
266 | * The user has performed a load from a hole in the file. Allocating | |
267 | * a new page in the file would cause excessive storage usage for | |
268 | * workloads with sparse files. We allocate a page cache page instead. | |
269 | * We'll kick it out of the page cache if it's ever written to, | |
270 | * otherwise it will simply fall out of the page cache under memory | |
271 | * pressure without ever having been dirtied. | |
272 | */ | |
273 | static int dax_load_hole(struct address_space *mapping, struct page *page, | |
274 | struct vm_fault *vmf) | |
275 | { | |
f7ca90b1 MW |
276 | if (!page) |
277 | page = find_or_create_page(mapping, vmf->pgoff, | |
278 | GFP_KERNEL | __GFP_ZERO); | |
279 | if (!page) | |
280 | return VM_FAULT_OOM; | |
f7ca90b1 MW |
281 | |
282 | vmf->page = page; | |
283 | return VM_FAULT_LOCKED; | |
284 | } | |
285 | ||
b2e0d162 DW |
286 | static int copy_user_bh(struct page *to, struct inode *inode, |
287 | struct buffer_head *bh, unsigned long vaddr) | |
f7ca90b1 | 288 | { |
b2e0d162 DW |
289 | struct blk_dax_ctl dax = { |
290 | .sector = to_sector(bh, inode), | |
291 | .size = bh->b_size, | |
292 | }; | |
293 | struct block_device *bdev = bh->b_bdev; | |
e2e05394 RZ |
294 | void *vto; |
295 | ||
b2e0d162 DW |
296 | if (dax_map_atomic(bdev, &dax) < 0) |
297 | return PTR_ERR(dax.addr); | |
f7ca90b1 | 298 | vto = kmap_atomic(to); |
b2e0d162 | 299 | copy_user_page(vto, (void __force *)dax.addr, vaddr, to); |
f7ca90b1 | 300 | kunmap_atomic(vto); |
b2e0d162 | 301 | dax_unmap_atomic(bdev, &dax); |
f7ca90b1 MW |
302 | return 0; |
303 | } | |
304 | ||
9973c98e | 305 | #define NO_SECTOR -1 |
09cbfeaf | 306 | #define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_SHIFT)) |
9973c98e RZ |
307 | |
308 | static int dax_radix_entry(struct address_space *mapping, pgoff_t index, | |
309 | sector_t sector, bool pmd_entry, bool dirty) | |
310 | { | |
311 | struct radix_tree_root *page_tree = &mapping->page_tree; | |
312 | pgoff_t pmd_index = DAX_PMD_INDEX(index); | |
313 | int type, error = 0; | |
314 | void *entry; | |
315 | ||
316 | WARN_ON_ONCE(pmd_entry && !dirty); | |
d2b2a28e DM |
317 | if (dirty) |
318 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
9973c98e RZ |
319 | |
320 | spin_lock_irq(&mapping->tree_lock); | |
321 | ||
322 | entry = radix_tree_lookup(page_tree, pmd_index); | |
323 | if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) { | |
324 | index = pmd_index; | |
325 | goto dirty; | |
326 | } | |
327 | ||
328 | entry = radix_tree_lookup(page_tree, index); | |
329 | if (entry) { | |
330 | type = RADIX_DAX_TYPE(entry); | |
331 | if (WARN_ON_ONCE(type != RADIX_DAX_PTE && | |
332 | type != RADIX_DAX_PMD)) { | |
333 | error = -EIO; | |
334 | goto unlock; | |
335 | } | |
336 | ||
337 | if (!pmd_entry || type == RADIX_DAX_PMD) | |
338 | goto dirty; | |
339 | ||
340 | /* | |
341 | * We only insert dirty PMD entries into the radix tree. This | |
342 | * means we don't need to worry about removing a dirty PTE | |
343 | * entry and inserting a clean PMD entry, thus reducing the | |
344 | * range we would flush with a follow-up fsync/msync call. | |
345 | */ | |
346 | radix_tree_delete(&mapping->page_tree, index); | |
347 | mapping->nrexceptional--; | |
348 | } | |
349 | ||
350 | if (sector == NO_SECTOR) { | |
351 | /* | |
352 | * This can happen during correct operation if our pfn_mkwrite | |
353 | * fault raced against a hole punch operation. If this | |
354 | * happens the pte that was hole punched will have been | |
355 | * unmapped and the radix tree entry will have been removed by | |
356 | * the time we are called, but the call will still happen. We | |
357 | * will return all the way up to wp_pfn_shared(), where the | |
358 | * pte_same() check will fail, eventually causing page fault | |
359 | * to be retried by the CPU. | |
360 | */ | |
361 | goto unlock; | |
362 | } | |
363 | ||
364 | error = radix_tree_insert(page_tree, index, | |
365 | RADIX_DAX_ENTRY(sector, pmd_entry)); | |
366 | if (error) | |
367 | goto unlock; | |
368 | ||
369 | mapping->nrexceptional++; | |
370 | dirty: | |
371 | if (dirty) | |
372 | radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); | |
373 | unlock: | |
374 | spin_unlock_irq(&mapping->tree_lock); | |
375 | return error; | |
376 | } | |
377 | ||
378 | static int dax_writeback_one(struct block_device *bdev, | |
379 | struct address_space *mapping, pgoff_t index, void *entry) | |
380 | { | |
381 | struct radix_tree_root *page_tree = &mapping->page_tree; | |
382 | int type = RADIX_DAX_TYPE(entry); | |
383 | struct radix_tree_node *node; | |
384 | struct blk_dax_ctl dax; | |
385 | void **slot; | |
386 | int ret = 0; | |
387 | ||
388 | spin_lock_irq(&mapping->tree_lock); | |
389 | /* | |
390 | * Regular page slots are stabilized by the page lock even | |
391 | * without the tree itself locked. These unlocked entries | |
392 | * need verification under the tree lock. | |
393 | */ | |
394 | if (!__radix_tree_lookup(page_tree, index, &node, &slot)) | |
395 | goto unlock; | |
396 | if (*slot != entry) | |
397 | goto unlock; | |
398 | ||
399 | /* another fsync thread may have already written back this entry */ | |
400 | if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) | |
401 | goto unlock; | |
402 | ||
403 | if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) { | |
404 | ret = -EIO; | |
405 | goto unlock; | |
406 | } | |
407 | ||
408 | dax.sector = RADIX_DAX_SECTOR(entry); | |
409 | dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE); | |
410 | spin_unlock_irq(&mapping->tree_lock); | |
411 | ||
412 | /* | |
413 | * We cannot hold tree_lock while calling dax_map_atomic() because it | |
414 | * eventually calls cond_resched(). | |
415 | */ | |
416 | ret = dax_map_atomic(bdev, &dax); | |
417 | if (ret < 0) | |
418 | return ret; | |
419 | ||
420 | if (WARN_ON_ONCE(ret < dax.size)) { | |
421 | ret = -EIO; | |
422 | goto unmap; | |
423 | } | |
424 | ||
425 | wb_cache_pmem(dax.addr, dax.size); | |
426 | ||
427 | spin_lock_irq(&mapping->tree_lock); | |
428 | radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); | |
429 | spin_unlock_irq(&mapping->tree_lock); | |
430 | unmap: | |
431 | dax_unmap_atomic(bdev, &dax); | |
432 | return ret; | |
433 | ||
434 | unlock: | |
435 | spin_unlock_irq(&mapping->tree_lock); | |
436 | return ret; | |
437 | } | |
438 | ||
439 | /* | |
440 | * Flush the mapping to the persistent domain within the byte range of [start, | |
441 | * end]. This is required by data integrity operations to ensure file data is | |
442 | * on persistent storage prior to completion of the operation. | |
443 | */ | |
7f6d5b52 RZ |
444 | int dax_writeback_mapping_range(struct address_space *mapping, |
445 | struct block_device *bdev, struct writeback_control *wbc) | |
9973c98e RZ |
446 | { |
447 | struct inode *inode = mapping->host; | |
9973c98e RZ |
448 | pgoff_t start_index, end_index, pmd_index; |
449 | pgoff_t indices[PAGEVEC_SIZE]; | |
450 | struct pagevec pvec; | |
451 | bool done = false; | |
452 | int i, ret = 0; | |
453 | void *entry; | |
454 | ||
455 | if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) | |
456 | return -EIO; | |
457 | ||
7f6d5b52 RZ |
458 | if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) |
459 | return 0; | |
460 | ||
09cbfeaf KS |
461 | start_index = wbc->range_start >> PAGE_SHIFT; |
462 | end_index = wbc->range_end >> PAGE_SHIFT; | |
9973c98e RZ |
463 | pmd_index = DAX_PMD_INDEX(start_index); |
464 | ||
465 | rcu_read_lock(); | |
466 | entry = radix_tree_lookup(&mapping->page_tree, pmd_index); | |
467 | rcu_read_unlock(); | |
468 | ||
469 | /* see if the start of our range is covered by a PMD entry */ | |
470 | if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) | |
471 | start_index = pmd_index; | |
472 | ||
473 | tag_pages_for_writeback(mapping, start_index, end_index); | |
474 | ||
475 | pagevec_init(&pvec, 0); | |
476 | while (!done) { | |
477 | pvec.nr = find_get_entries_tag(mapping, start_index, | |
478 | PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE, | |
479 | pvec.pages, indices); | |
480 | ||
481 | if (pvec.nr == 0) | |
482 | break; | |
483 | ||
484 | for (i = 0; i < pvec.nr; i++) { | |
485 | if (indices[i] > end_index) { | |
486 | done = true; | |
487 | break; | |
488 | } | |
489 | ||
490 | ret = dax_writeback_one(bdev, mapping, indices[i], | |
491 | pvec.pages[i]); | |
492 | if (ret < 0) | |
493 | return ret; | |
494 | } | |
495 | } | |
496 | wmb_pmem(); | |
497 | return 0; | |
498 | } | |
499 | EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); | |
500 | ||
f7ca90b1 MW |
501 | static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, |
502 | struct vm_area_struct *vma, struct vm_fault *vmf) | |
503 | { | |
f7ca90b1 | 504 | unsigned long vaddr = (unsigned long)vmf->virtual_address; |
b2e0d162 DW |
505 | struct address_space *mapping = inode->i_mapping; |
506 | struct block_device *bdev = bh->b_bdev; | |
507 | struct blk_dax_ctl dax = { | |
508 | .sector = to_sector(bh, inode), | |
509 | .size = bh->b_size, | |
510 | }; | |
f7ca90b1 MW |
511 | int error; |
512 | ||
0f90cc66 RZ |
513 | i_mmap_lock_read(mapping); |
514 | ||
b2e0d162 DW |
515 | if (dax_map_atomic(bdev, &dax) < 0) { |
516 | error = PTR_ERR(dax.addr); | |
f7ca90b1 MW |
517 | goto out; |
518 | } | |
b2e0d162 | 519 | dax_unmap_atomic(bdev, &dax); |
f7ca90b1 | 520 | |
9973c98e RZ |
521 | error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false, |
522 | vmf->flags & FAULT_FLAG_WRITE); | |
523 | if (error) | |
524 | goto out; | |
525 | ||
01c8f1c4 | 526 | error = vm_insert_mixed(vma, vaddr, dax.pfn); |
f7ca90b1 MW |
527 | |
528 | out: | |
0f90cc66 RZ |
529 | i_mmap_unlock_read(mapping); |
530 | ||
f7ca90b1 MW |
531 | return error; |
532 | } | |
533 | ||
ce5c5d55 DC |
534 | /** |
535 | * __dax_fault - handle a page fault on a DAX file | |
536 | * @vma: The virtual memory area where the fault occurred | |
537 | * @vmf: The description of the fault | |
538 | * @get_block: The filesystem method used to translate file offsets to blocks | |
539 | * | |
540 | * When a page fault occurs, filesystems may call this helper in their | |
541 | * fault handler for DAX files. __dax_fault() assumes the caller has done all | |
542 | * the necessary locking for the page fault to proceed successfully. | |
543 | */ | |
544 | int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, | |
02fbd139 | 545 | get_block_t get_block) |
f7ca90b1 MW |
546 | { |
547 | struct file *file = vma->vm_file; | |
548 | struct address_space *mapping = file->f_mapping; | |
549 | struct inode *inode = mapping->host; | |
550 | struct page *page; | |
551 | struct buffer_head bh; | |
552 | unsigned long vaddr = (unsigned long)vmf->virtual_address; | |
553 | unsigned blkbits = inode->i_blkbits; | |
554 | sector_t block; | |
555 | pgoff_t size; | |
556 | int error; | |
557 | int major = 0; | |
558 | ||
559 | size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
560 | if (vmf->pgoff >= size) | |
561 | return VM_FAULT_SIGBUS; | |
562 | ||
563 | memset(&bh, 0, sizeof(bh)); | |
564 | block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits); | |
eab95db6 | 565 | bh.b_bdev = inode->i_sb->s_bdev; |
f7ca90b1 MW |
566 | bh.b_size = PAGE_SIZE; |
567 | ||
568 | repeat: | |
569 | page = find_get_page(mapping, vmf->pgoff); | |
570 | if (page) { | |
571 | if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) { | |
09cbfeaf | 572 | put_page(page); |
f7ca90b1 MW |
573 | return VM_FAULT_RETRY; |
574 | } | |
575 | if (unlikely(page->mapping != mapping)) { | |
576 | unlock_page(page); | |
09cbfeaf | 577 | put_page(page); |
f7ca90b1 MW |
578 | goto repeat; |
579 | } | |
f7ca90b1 MW |
580 | } |
581 | ||
582 | error = get_block(inode, block, &bh, 0); | |
583 | if (!error && (bh.b_size < PAGE_SIZE)) | |
584 | error = -EIO; /* fs corruption? */ | |
585 | if (error) | |
0f90cc66 | 586 | goto unlock_page; |
f7ca90b1 | 587 | |
aef39ab1 | 588 | if (!buffer_mapped(&bh) && !vmf->cow_page) { |
f7ca90b1 MW |
589 | if (vmf->flags & FAULT_FLAG_WRITE) { |
590 | error = get_block(inode, block, &bh, 1); | |
591 | count_vm_event(PGMAJFAULT); | |
592 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); | |
593 | major = VM_FAULT_MAJOR; | |
594 | if (!error && (bh.b_size < PAGE_SIZE)) | |
595 | error = -EIO; | |
596 | if (error) | |
0f90cc66 | 597 | goto unlock_page; |
f7ca90b1 MW |
598 | } else { |
599 | return dax_load_hole(mapping, page, vmf); | |
600 | } | |
601 | } | |
602 | ||
603 | if (vmf->cow_page) { | |
604 | struct page *new_page = vmf->cow_page; | |
605 | if (buffer_written(&bh)) | |
b2e0d162 | 606 | error = copy_user_bh(new_page, inode, &bh, vaddr); |
f7ca90b1 MW |
607 | else |
608 | clear_user_highpage(new_page, vaddr); | |
609 | if (error) | |
0f90cc66 | 610 | goto unlock_page; |
f7ca90b1 | 611 | vmf->page = page; |
7795bec8 | 612 | if (!page) |
0f90cc66 | 613 | i_mmap_lock_read(mapping); |
f7ca90b1 MW |
614 | return VM_FAULT_LOCKED; |
615 | } | |
616 | ||
617 | /* Check we didn't race with a read fault installing a new page */ | |
618 | if (!page && major) | |
619 | page = find_lock_page(mapping, vmf->pgoff); | |
620 | ||
621 | if (page) { | |
622 | unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, | |
09cbfeaf | 623 | PAGE_SIZE, 0); |
f7ca90b1 MW |
624 | delete_from_page_cache(page); |
625 | unlock_page(page); | |
09cbfeaf | 626 | put_page(page); |
9973c98e | 627 | page = NULL; |
f7ca90b1 MW |
628 | } |
629 | ||
02fbd139 | 630 | /* Filesystem should not return unwritten buffers to us! */ |
2b10945c | 631 | WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); |
f7ca90b1 MW |
632 | error = dax_insert_mapping(inode, &bh, vma, vmf); |
633 | ||
634 | out: | |
635 | if (error == -ENOMEM) | |
636 | return VM_FAULT_OOM | major; | |
637 | /* -EBUSY is fine, somebody else faulted on the same PTE */ | |
638 | if ((error < 0) && (error != -EBUSY)) | |
639 | return VM_FAULT_SIGBUS | major; | |
640 | return VM_FAULT_NOPAGE | major; | |
641 | ||
0f90cc66 | 642 | unlock_page: |
f7ca90b1 MW |
643 | if (page) { |
644 | unlock_page(page); | |
09cbfeaf | 645 | put_page(page); |
f7ca90b1 MW |
646 | } |
647 | goto out; | |
648 | } | |
ce5c5d55 | 649 | EXPORT_SYMBOL(__dax_fault); |
f7ca90b1 MW |
650 | |
651 | /** | |
652 | * dax_fault - handle a page fault on a DAX file | |
653 | * @vma: The virtual memory area where the fault occurred | |
654 | * @vmf: The description of the fault | |
655 | * @get_block: The filesystem method used to translate file offsets to blocks | |
656 | * | |
657 | * When a page fault occurs, filesystems may call this helper in their | |
658 | * fault handler for DAX files. | |
659 | */ | |
660 | int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, | |
02fbd139 | 661 | get_block_t get_block) |
f7ca90b1 MW |
662 | { |
663 | int result; | |
664 | struct super_block *sb = file_inode(vma->vm_file)->i_sb; | |
665 | ||
666 | if (vmf->flags & FAULT_FLAG_WRITE) { | |
667 | sb_start_pagefault(sb); | |
668 | file_update_time(vma->vm_file); | |
669 | } | |
02fbd139 | 670 | result = __dax_fault(vma, vmf, get_block); |
f7ca90b1 MW |
671 | if (vmf->flags & FAULT_FLAG_WRITE) |
672 | sb_end_pagefault(sb); | |
673 | ||
674 | return result; | |
675 | } | |
676 | EXPORT_SYMBOL_GPL(dax_fault); | |
4c0ccfef | 677 | |
348e967a | 678 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) |
844f35db MW |
679 | /* |
680 | * The 'colour' (ie low bits) within a PMD of a page offset. This comes up | |
681 | * more often than one might expect in the below function. | |
682 | */ | |
683 | #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) | |
684 | ||
cbb38e41 DW |
685 | static void __dax_dbg(struct buffer_head *bh, unsigned long address, |
686 | const char *reason, const char *fn) | |
687 | { | |
688 | if (bh) { | |
689 | char bname[BDEVNAME_SIZE]; | |
690 | bdevname(bh->b_bdev, bname); | |
691 | pr_debug("%s: %s addr: %lx dev %s state %lx start %lld " | |
692 | "length %zd fallback: %s\n", fn, current->comm, | |
693 | address, bname, bh->b_state, (u64)bh->b_blocknr, | |
694 | bh->b_size, reason); | |
695 | } else { | |
696 | pr_debug("%s: %s addr: %lx fallback: %s\n", fn, | |
697 | current->comm, address, reason); | |
698 | } | |
699 | } | |
700 | ||
701 | #define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd") | |
702 | ||
844f35db | 703 | int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, |
02fbd139 | 704 | pmd_t *pmd, unsigned int flags, get_block_t get_block) |
844f35db MW |
705 | { |
706 | struct file *file = vma->vm_file; | |
707 | struct address_space *mapping = file->f_mapping; | |
708 | struct inode *inode = mapping->host; | |
709 | struct buffer_head bh; | |
710 | unsigned blkbits = inode->i_blkbits; | |
711 | unsigned long pmd_addr = address & PMD_MASK; | |
712 | bool write = flags & FAULT_FLAG_WRITE; | |
b2e0d162 | 713 | struct block_device *bdev; |
844f35db | 714 | pgoff_t size, pgoff; |
b2e0d162 | 715 | sector_t block; |
9973c98e RZ |
716 | int error, result = 0; |
717 | bool alloc = false; | |
844f35db | 718 | |
c046c321 | 719 | /* dax pmd mappings require pfn_t_devmap() */ |
ee82c9ed DW |
720 | if (!IS_ENABLED(CONFIG_FS_DAX_PMD)) |
721 | return VM_FAULT_FALLBACK; | |
722 | ||
844f35db | 723 | /* Fall back to PTEs if we're going to COW */ |
59bf4fb9 TK |
724 | if (write && !(vma->vm_flags & VM_SHARED)) { |
725 | split_huge_pmd(vma, pmd, address); | |
cbb38e41 | 726 | dax_pmd_dbg(NULL, address, "cow write"); |
844f35db | 727 | return VM_FAULT_FALLBACK; |
59bf4fb9 | 728 | } |
844f35db | 729 | /* If the PMD would extend outside the VMA */ |
cbb38e41 DW |
730 | if (pmd_addr < vma->vm_start) { |
731 | dax_pmd_dbg(NULL, address, "vma start unaligned"); | |
844f35db | 732 | return VM_FAULT_FALLBACK; |
cbb38e41 DW |
733 | } |
734 | if ((pmd_addr + PMD_SIZE) > vma->vm_end) { | |
735 | dax_pmd_dbg(NULL, address, "vma end unaligned"); | |
844f35db | 736 | return VM_FAULT_FALLBACK; |
cbb38e41 | 737 | } |
844f35db | 738 | |
3fdd1b47 | 739 | pgoff = linear_page_index(vma, pmd_addr); |
844f35db MW |
740 | size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; |
741 | if (pgoff >= size) | |
742 | return VM_FAULT_SIGBUS; | |
743 | /* If the PMD would cover blocks out of the file */ | |
cbb38e41 DW |
744 | if ((pgoff | PG_PMD_COLOUR) >= size) { |
745 | dax_pmd_dbg(NULL, address, | |
746 | "offset + huge page size > file size"); | |
844f35db | 747 | return VM_FAULT_FALLBACK; |
cbb38e41 | 748 | } |
844f35db MW |
749 | |
750 | memset(&bh, 0, sizeof(bh)); | |
d4bbe706 | 751 | bh.b_bdev = inode->i_sb->s_bdev; |
844f35db MW |
752 | block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); |
753 | ||
754 | bh.b_size = PMD_SIZE; | |
9973c98e RZ |
755 | |
756 | if (get_block(inode, block, &bh, 0) != 0) | |
844f35db | 757 | return VM_FAULT_SIGBUS; |
9973c98e RZ |
758 | |
759 | if (!buffer_mapped(&bh) && write) { | |
760 | if (get_block(inode, block, &bh, 1) != 0) | |
761 | return VM_FAULT_SIGBUS; | |
762 | alloc = true; | |
2b10945c | 763 | WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); |
9973c98e RZ |
764 | } |
765 | ||
b2e0d162 | 766 | bdev = bh.b_bdev; |
844f35db MW |
767 | |
768 | /* | |
769 | * If the filesystem isn't willing to tell us the length of a hole, | |
770 | * just fall back to PTEs. Calling get_block 512 times in a loop | |
771 | * would be silly. | |
772 | */ | |
cbb38e41 DW |
773 | if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) { |
774 | dax_pmd_dbg(&bh, address, "allocated block too small"); | |
9973c98e RZ |
775 | return VM_FAULT_FALLBACK; |
776 | } | |
777 | ||
778 | /* | |
779 | * If we allocated new storage, make sure no process has any | |
780 | * zero pages covering this hole | |
781 | */ | |
782 | if (alloc) { | |
783 | loff_t lstart = pgoff << PAGE_SHIFT; | |
784 | loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */ | |
785 | ||
786 | truncate_pagecache_range(inode, lstart, lend); | |
cbb38e41 | 787 | } |
844f35db | 788 | |
de14b9cb | 789 | i_mmap_lock_read(mapping); |
46c043ed | 790 | |
b9953536 | 791 | if (!write && !buffer_mapped(&bh)) { |
844f35db | 792 | spinlock_t *ptl; |
d295e341 | 793 | pmd_t entry; |
844f35db | 794 | struct page *zero_page = get_huge_zero_page(); |
d295e341 | 795 | |
cbb38e41 DW |
796 | if (unlikely(!zero_page)) { |
797 | dax_pmd_dbg(&bh, address, "no zero page"); | |
844f35db | 798 | goto fallback; |
cbb38e41 | 799 | } |
844f35db | 800 | |
d295e341 KS |
801 | ptl = pmd_lock(vma->vm_mm, pmd); |
802 | if (!pmd_none(*pmd)) { | |
803 | spin_unlock(ptl); | |
cbb38e41 | 804 | dax_pmd_dbg(&bh, address, "pmd already present"); |
d295e341 KS |
805 | goto fallback; |
806 | } | |
807 | ||
cbb38e41 DW |
808 | dev_dbg(part_to_dev(bdev->bd_part), |
809 | "%s: %s addr: %lx pfn: <zero> sect: %llx\n", | |
810 | __func__, current->comm, address, | |
811 | (unsigned long long) to_sector(&bh, inode)); | |
812 | ||
d295e341 KS |
813 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
814 | entry = pmd_mkhuge(entry); | |
815 | set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry); | |
844f35db | 816 | result = VM_FAULT_NOPAGE; |
d295e341 | 817 | spin_unlock(ptl); |
844f35db | 818 | } else { |
b2e0d162 DW |
819 | struct blk_dax_ctl dax = { |
820 | .sector = to_sector(&bh, inode), | |
821 | .size = PMD_SIZE, | |
822 | }; | |
823 | long length = dax_map_atomic(bdev, &dax); | |
824 | ||
844f35db | 825 | if (length < 0) { |
8b3db979 DW |
826 | dax_pmd_dbg(&bh, address, "dax-error fallback"); |
827 | goto fallback; | |
844f35db | 828 | } |
cbb38e41 DW |
829 | if (length < PMD_SIZE) { |
830 | dax_pmd_dbg(&bh, address, "dax-length too small"); | |
831 | dax_unmap_atomic(bdev, &dax); | |
832 | goto fallback; | |
833 | } | |
834 | if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) { | |
835 | dax_pmd_dbg(&bh, address, "pfn unaligned"); | |
b2e0d162 | 836 | dax_unmap_atomic(bdev, &dax); |
844f35db | 837 | goto fallback; |
b2e0d162 | 838 | } |
844f35db | 839 | |
c046c321 | 840 | if (!pfn_t_devmap(dax.pfn)) { |
b2e0d162 | 841 | dax_unmap_atomic(bdev, &dax); |
cbb38e41 | 842 | dax_pmd_dbg(&bh, address, "pfn not in memmap"); |
152d7bd8 | 843 | goto fallback; |
b2e0d162 | 844 | } |
b2e0d162 | 845 | dax_unmap_atomic(bdev, &dax); |
0f90cc66 | 846 | |
9973c98e RZ |
847 | /* |
848 | * For PTE faults we insert a radix tree entry for reads, and | |
849 | * leave it clean. Then on the first write we dirty the radix | |
850 | * tree entry via the dax_pfn_mkwrite() path. This sequence | |
851 | * allows the dax_pfn_mkwrite() call to be simpler and avoid a | |
852 | * call into get_block() to translate the pgoff to a sector in | |
853 | * order to be able to create a new radix tree entry. | |
854 | * | |
855 | * The PMD path doesn't have an equivalent to | |
856 | * dax_pfn_mkwrite(), though, so for a read followed by a | |
857 | * write we traverse all the way through __dax_pmd_fault() | |
858 | * twice. This means we can just skip inserting a radix tree | |
859 | * entry completely on the initial read and just wait until | |
860 | * the write to insert a dirty entry. | |
861 | */ | |
862 | if (write) { | |
863 | error = dax_radix_entry(mapping, pgoff, dax.sector, | |
864 | true, true); | |
865 | if (error) { | |
866 | dax_pmd_dbg(&bh, address, | |
867 | "PMD radix insertion failed"); | |
868 | goto fallback; | |
869 | } | |
870 | } | |
871 | ||
cbb38e41 DW |
872 | dev_dbg(part_to_dev(bdev->bd_part), |
873 | "%s: %s addr: %lx pfn: %lx sect: %llx\n", | |
874 | __func__, current->comm, address, | |
875 | pfn_t_to_pfn(dax.pfn), | |
876 | (unsigned long long) dax.sector); | |
34c0fd54 | 877 | result |= vmf_insert_pfn_pmd(vma, address, pmd, |
f25748e3 | 878 | dax.pfn, write); |
844f35db MW |
879 | } |
880 | ||
881 | out: | |
0f90cc66 RZ |
882 | i_mmap_unlock_read(mapping); |
883 | ||
844f35db MW |
884 | return result; |
885 | ||
886 | fallback: | |
887 | count_vm_event(THP_FAULT_FALLBACK); | |
888 | result = VM_FAULT_FALLBACK; | |
889 | goto out; | |
890 | } | |
891 | EXPORT_SYMBOL_GPL(__dax_pmd_fault); | |
892 | ||
893 | /** | |
894 | * dax_pmd_fault - handle a PMD fault on a DAX file | |
895 | * @vma: The virtual memory area where the fault occurred | |
896 | * @vmf: The description of the fault | |
897 | * @get_block: The filesystem method used to translate file offsets to blocks | |
898 | * | |
899 | * When a page fault occurs, filesystems may call this helper in their | |
900 | * pmd_fault handler for DAX files. | |
901 | */ | |
902 | int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, | |
02fbd139 | 903 | pmd_t *pmd, unsigned int flags, get_block_t get_block) |
844f35db MW |
904 | { |
905 | int result; | |
906 | struct super_block *sb = file_inode(vma->vm_file)->i_sb; | |
907 | ||
908 | if (flags & FAULT_FLAG_WRITE) { | |
909 | sb_start_pagefault(sb); | |
910 | file_update_time(vma->vm_file); | |
911 | } | |
02fbd139 | 912 | result = __dax_pmd_fault(vma, address, pmd, flags, get_block); |
844f35db MW |
913 | if (flags & FAULT_FLAG_WRITE) |
914 | sb_end_pagefault(sb); | |
915 | ||
916 | return result; | |
917 | } | |
918 | EXPORT_SYMBOL_GPL(dax_pmd_fault); | |
dd8a2b6c | 919 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
844f35db | 920 | |
0e3b210c BH |
921 | /** |
922 | * dax_pfn_mkwrite - handle first write to DAX page | |
923 | * @vma: The virtual memory area where the fault occurred | |
924 | * @vmf: The description of the fault | |
0e3b210c BH |
925 | */ |
926 | int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) | |
927 | { | |
9973c98e | 928 | struct file *file = vma->vm_file; |
30f471fd | 929 | int error; |
0e3b210c | 930 | |
9973c98e RZ |
931 | /* |
932 | * We pass NO_SECTOR to dax_radix_entry() because we expect that a | |
933 | * RADIX_DAX_PTE entry already exists in the radix tree from a | |
934 | * previous call to __dax_fault(). We just want to look up that PTE | |
935 | * entry using vmf->pgoff and make sure the dirty tag is set. This | |
936 | * saves us from having to make a call to get_block() here to look | |
937 | * up the sector. | |
938 | */ | |
30f471fd RZ |
939 | error = dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false, |
940 | true); | |
941 | ||
942 | if (error == -ENOMEM) | |
943 | return VM_FAULT_OOM; | |
944 | if (error) | |
945 | return VM_FAULT_SIGBUS; | |
0e3b210c BH |
946 | return VM_FAULT_NOPAGE; |
947 | } | |
948 | EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); | |
949 | ||
4b0228fa VV |
950 | static bool dax_range_is_aligned(struct block_device *bdev, |
951 | unsigned int offset, unsigned int length) | |
952 | { | |
953 | unsigned short sector_size = bdev_logical_block_size(bdev); | |
954 | ||
955 | if (!IS_ALIGNED(offset, sector_size)) | |
956 | return false; | |
957 | if (!IS_ALIGNED(length, sector_size)) | |
958 | return false; | |
959 | ||
960 | return true; | |
961 | } | |
962 | ||
679c8bd3 CH |
963 | int __dax_zero_page_range(struct block_device *bdev, sector_t sector, |
964 | unsigned int offset, unsigned int length) | |
965 | { | |
966 | struct blk_dax_ctl dax = { | |
967 | .sector = sector, | |
968 | .size = PAGE_SIZE, | |
969 | }; | |
970 | ||
4b0228fa VV |
971 | if (dax_range_is_aligned(bdev, offset, length)) { |
972 | sector_t start_sector = dax.sector + (offset >> 9); | |
973 | ||
974 | return blkdev_issue_zeroout(bdev, start_sector, | |
975 | length >> 9, GFP_NOFS, true); | |
976 | } else { | |
977 | if (dax_map_atomic(bdev, &dax) < 0) | |
978 | return PTR_ERR(dax.addr); | |
979 | clear_pmem(dax.addr + offset, length); | |
980 | wmb_pmem(); | |
981 | dax_unmap_atomic(bdev, &dax); | |
982 | } | |
679c8bd3 CH |
983 | return 0; |
984 | } | |
985 | EXPORT_SYMBOL_GPL(__dax_zero_page_range); | |
986 | ||
4c0ccfef | 987 | /** |
25726bc1 | 988 | * dax_zero_page_range - zero a range within a page of a DAX file |
4c0ccfef MW |
989 | * @inode: The file being truncated |
990 | * @from: The file offset that is being truncated to | |
25726bc1 | 991 | * @length: The number of bytes to zero |
4c0ccfef MW |
992 | * @get_block: The filesystem method used to translate file offsets to blocks |
993 | * | |
25726bc1 MW |
994 | * This function can be called by a filesystem when it is zeroing part of a |
995 | * page in a DAX file. This is intended for hole-punch operations. If | |
996 | * you are truncating a file, the helper function dax_truncate_page() may be | |
997 | * more convenient. | |
4c0ccfef | 998 | */ |
25726bc1 MW |
999 | int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, |
1000 | get_block_t get_block) | |
4c0ccfef MW |
1001 | { |
1002 | struct buffer_head bh; | |
09cbfeaf KS |
1003 | pgoff_t index = from >> PAGE_SHIFT; |
1004 | unsigned offset = from & (PAGE_SIZE-1); | |
4c0ccfef MW |
1005 | int err; |
1006 | ||
1007 | /* Block boundary? Nothing to do */ | |
1008 | if (!length) | |
1009 | return 0; | |
09cbfeaf | 1010 | BUG_ON((offset + length) > PAGE_SIZE); |
4c0ccfef MW |
1011 | |
1012 | memset(&bh, 0, sizeof(bh)); | |
eab95db6 | 1013 | bh.b_bdev = inode->i_sb->s_bdev; |
09cbfeaf | 1014 | bh.b_size = PAGE_SIZE; |
4c0ccfef | 1015 | err = get_block(inode, index, &bh, 0); |
679c8bd3 | 1016 | if (err < 0 || !buffer_written(&bh)) |
4c0ccfef | 1017 | return err; |
b2e0d162 | 1018 | |
679c8bd3 CH |
1019 | return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode), |
1020 | offset, length); | |
4c0ccfef | 1021 | } |
25726bc1 MW |
1022 | EXPORT_SYMBOL_GPL(dax_zero_page_range); |
1023 | ||
1024 | /** | |
1025 | * dax_truncate_page - handle a partial page being truncated in a DAX file | |
1026 | * @inode: The file being truncated | |
1027 | * @from: The file offset that is being truncated to | |
1028 | * @get_block: The filesystem method used to translate file offsets to blocks | |
1029 | * | |
1030 | * Similar to block_truncate_page(), this function can be called by a | |
1031 | * filesystem when it is truncating a DAX file to handle the partial page. | |
25726bc1 MW |
1032 | */ |
1033 | int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) | |
1034 | { | |
09cbfeaf | 1035 | unsigned length = PAGE_ALIGN(from) - from; |
25726bc1 MW |
1036 | return dax_zero_page_range(inode, from, length, get_block); |
1037 | } | |
4c0ccfef | 1038 | EXPORT_SYMBOL_GPL(dax_truncate_page); |