1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * fs/dax.c - Direct Access filesystem code |
4 | * Copyright (c) 2013-2014 Intel Corporation |
5 | * Author: Matthew Wilcox <matthew.r.wilcox@intel.com> |
6 | * Author: Ross Zwisler <ross.zwisler@linux.intel.com> |
7 | */ |
8 | |
9 | #include <linux/atomic.h> |
10 | #include <linux/blkdev.h> |
11 | #include <linux/buffer_head.h> |
12 | #include <linux/dax.h> |
13 | #include <linux/fs.h> |
14 | #include <linux/highmem.h> |
15 | #include <linux/memcontrol.h> |
16 | #include <linux/mm.h> |
17 | #include <linux/mutex.h> |
18 | #include <linux/pagevec.h> |
19 | #include <linux/sched.h> |
20 | #include <linux/sched/signal.h> |
21 | #include <linux/uio.h> |
22 | #include <linux/vmstat.h> |
23 | #include <linux/pfn_t.h> |
24 | #include <linux/sizes.h> |
25 | #include <linux/mmu_notifier.h> |
26 | #include <linux/iomap.h> |
27 | #include <linux/rmap.h> |
28 | #include <asm/pgalloc.h> |
29 | |
30 | #define CREATE_TRACE_POINTS |
31 | #include <trace/events/fs_dax.h> |
32 | |
33 | /* We choose 4096 entries - same as per-zone page wait tables */ |
34 | #define DAX_WAIT_TABLE_BITS 12 |
35 | #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS) |
36 | |
37 | /* The 'colour' (ie low bits) within a PMD of a page offset. */ |
38 | #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) |
39 | #define PG_PMD_NR (PMD_SIZE >> PAGE_SHIFT) |
40 | |
41 | static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; |
42 | |
43 | static int __init init_dax_wait_table(void) |
44 | { |
45 | int i; |
46 | |
47 | for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++) |
48 | init_waitqueue_head(wait_table + i); |
49 | return 0; |
50 | } |
51 | fs_initcall(init_dax_wait_table); |
52 | |
53 | /* |
54 | * DAX pagecache entries use XArray value entries so they can't be mistaken |
55 | * for pages. We use one bit for locking, one bit for the entry size (PMD) |
56 | * and two more to tell us if the entry is a zero page or an empty entry that |
57 | * is just used for locking. In total four special bits. |
58 | * |
59 | * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE |
60 | * and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem |
61 | * block allocation. |
62 | */ |
63 | #define DAX_SHIFT (4) |
64 | #define DAX_LOCKED (1UL << 0) |
65 | #define DAX_PMD (1UL << 1) |
66 | #define DAX_ZERO_PAGE (1UL << 2) |
67 | #define DAX_EMPTY (1UL << 3) |
68 | |
69 | static unsigned long dax_to_pfn(void *entry) |
70 | { |
71 | return xa_to_value(entry) >> DAX_SHIFT; |
72 | } |
73 | |
74 | static void *dax_make_entry(pfn_t pfn, unsigned long flags) |
75 | { |
76 | return xa_mk_value(v: flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT)); |
77 | } |
78 | |
79 | static bool dax_is_locked(void *entry) |
80 | { |
81 | return xa_to_value(entry) & DAX_LOCKED; |
82 | } |
83 | |
84 | static unsigned int dax_entry_order(void *entry) |
85 | { |
86 | if (xa_to_value(entry) & DAX_PMD) |
87 | return PMD_ORDER; |
88 | return 0; |
89 | } |
90 | |
91 | static unsigned long dax_is_pmd_entry(void *entry) |
92 | { |
93 | return xa_to_value(entry) & DAX_PMD; |
94 | } |
95 | |
96 | static bool dax_is_pte_entry(void *entry) |
97 | { |
98 | return !(xa_to_value(entry) & DAX_PMD); |
99 | } |
100 | |
101 | static int dax_is_zero_entry(void *entry) |
102 | { |
103 | return xa_to_value(entry) & DAX_ZERO_PAGE; |
104 | } |
105 | |
106 | static int dax_is_empty_entry(void *entry) |
107 | { |
108 | return xa_to_value(entry) & DAX_EMPTY; |
109 | } |
110 | |
111 | /* |
112 | * true if the entry that was found is of a smaller order than the entry |
113 | * we were looking for |
114 | */ |
115 | static bool dax_is_conflict(void *entry) |
116 | { |
117 | return entry == XA_RETRY_ENTRY; |
118 | } |
119 | |
120 | /* |
121 | * DAX page cache entry locking |
122 | */ |
123 | struct exceptional_entry_key { |
124 | struct xarray *xa; |
125 | pgoff_t entry_start; |
126 | }; |
127 | |
128 | struct wait_exceptional_entry_queue { |
129 | wait_queue_entry_t wait; |
130 | struct exceptional_entry_key key; |
131 | }; |
132 | |
133 | /** |
134 | * enum dax_wake_mode: waitqueue wakeup behaviour |
135 | * @WAKE_ALL: wake all waiters in the waitqueue |
136 | * @WAKE_NEXT: wake only the first waiter in the waitqueue |
137 | */ |
138 | enum dax_wake_mode { |
139 | WAKE_ALL, |
140 | WAKE_NEXT, |
141 | }; |
142 | |
143 | static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas, |
144 | void *entry, struct exceptional_entry_key *key) |
145 | { |
146 | unsigned long hash; |
147 | unsigned long index = xas->xa_index; |
148 | |
149 | /* |
150 | * If 'entry' is a PMD, align the 'index' that we use for the wait |
151 | * queue to the start of that PMD. This ensures that all offsets in |
152 | * the range covered by the PMD map to the same bit lock. |
153 | */ |
154 | if (dax_is_pmd_entry(entry)) |
155 | index &= ~PG_PMD_COLOUR; |
156 | key->xa = xas->xa; |
157 | key->entry_start = index; |
158 | |
159 | hash = hash_long((unsigned long)xas->xa ^ index, DAX_WAIT_TABLE_BITS); |
160 | return wait_table + hash; |
161 | } |
162 | |
163 | static int wake_exceptional_entry_func(wait_queue_entry_t *wait, |
164 | unsigned int mode, int sync, void *keyp) |
165 | { |
166 | struct exceptional_entry_key *key = keyp; |
167 | struct wait_exceptional_entry_queue *ewait = |
168 | container_of(wait, struct wait_exceptional_entry_queue, wait); |
169 | |
170 | if (key->xa != ewait->key.xa || |
171 | key->entry_start != ewait->key.entry_start) |
172 | return 0; |
173 | return autoremove_wake_function(wq_entry: wait, mode, sync, NULL); |
174 | } |
175 | |
176 | /* |
177 | * @entry may no longer be the entry at the index in the mapping. |
178 | * The important information it's conveying is whether the entry at |
179 | * this index used to be a PMD entry. |
180 | */ |
181 | static void dax_wake_entry(struct xa_state *xas, void *entry, |
182 | enum dax_wake_mode mode) |
183 | { |
184 | struct exceptional_entry_key key; |
185 | wait_queue_head_t *wq; |
186 | |
187 | wq = dax_entry_waitqueue(xas, entry, key: &key); |
188 | |
189 | /* |
190 | * Checking for locked entry and prepare_to_wait_exclusive() happens |
191 | * under the i_pages lock, ditto for entry handling in our callers. |
192 | * So at this point all tasks that could have seen our entry locked |
193 | * must be in the waitqueue and the following check will see them. |
194 | */ |
195 | if (waitqueue_active(wq_head: wq)) |
196 | __wake_up(wq_head: wq, TASK_NORMAL, nr: mode == WAKE_ALL ? 0 : 1, key: &key); |
197 | } |
198 | |
199 | /* |
200 | * Look up entry in page cache, wait for it to become unlocked if it |
201 | * is a DAX entry and return it. The caller must subsequently call |
202 | * put_unlocked_entry() if it did not lock the entry or dax_unlock_entry() |
203 | * if it did. The entry returned may have a larger order than @order. |
204 | * If @order is larger than the order of the entry found in i_pages, this |
205 | * function returns a dax_is_conflict entry. |
206 | * |
207 | * Must be called with the i_pages lock held. |
208 | */ |
209 | static void *get_unlocked_entry(struct xa_state *xas, unsigned int order) |
210 | { |
211 | void *entry; |
212 | struct wait_exceptional_entry_queue ewait; |
213 | wait_queue_head_t *wq; |
214 | |
215 | init_wait(&ewait.wait); |
216 | ewait.wait.func = wake_exceptional_entry_func; |
217 | |
218 | for (;;) { |
219 | entry = xas_find_conflict(xas); |
220 | if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) |
221 | return entry; |
222 | if (dax_entry_order(entry) < order) |
223 | return XA_RETRY_ENTRY; |
224 | if (!dax_is_locked(entry)) |
225 | return entry; |
226 | |
227 | wq = dax_entry_waitqueue(xas, entry, key: &ewait.key); |
228 | prepare_to_wait_exclusive(wq_head: wq, wq_entry: &ewait.wait, |
229 | TASK_UNINTERRUPTIBLE); |
230 | xas_unlock_irq(xas); |
231 | xas_reset(xas); |
232 | schedule(); |
233 | finish_wait(wq_head: wq, wq_entry: &ewait.wait); |
234 | xas_lock_irq(xas); |
235 | } |
236 | } |
237 | |
238 | /* |
239 | * The only thing keeping the address space around is the i_pages lock |
240 | * (it's cycled in clear_inode() after removing the entries from i_pages) |
241 | * After we call xas_unlock_irq(), we cannot touch xas->xa. |
242 | */ |
243 | static void wait_entry_unlocked(struct xa_state *xas, void *entry) |
244 | { |
245 | struct wait_exceptional_entry_queue ewait; |
246 | wait_queue_head_t *wq; |
247 | |
248 | init_wait(&ewait.wait); |
249 | ewait.wait.func = wake_exceptional_entry_func; |
250 | |
251 | wq = dax_entry_waitqueue(xas, entry, key: &ewait.key); |
252 | /* |
253 | * Unlike get_unlocked_entry() there is no guarantee that this |
254 | * path ever successfully retrieves an unlocked entry before an |
255 | * inode dies. Perform a non-exclusive wait in case this path |
256 | * never successfully performs its own wake up. |
257 | */ |
258 | prepare_to_wait(wq_head: wq, wq_entry: &ewait.wait, TASK_UNINTERRUPTIBLE); |
259 | xas_unlock_irq(xas); |
260 | schedule(); |
261 | finish_wait(wq_head: wq, wq_entry: &ewait.wait); |
262 | } |
263 | |
264 | static void put_unlocked_entry(struct xa_state *xas, void *entry, |
265 | enum dax_wake_mode mode) |
266 | { |
267 | if (entry && !dax_is_conflict(entry)) |
268 | dax_wake_entry(xas, entry, mode); |
269 | } |
270 | |
271 | /* |
272 | * We used the xa_state to get the entry, but then we locked the entry and |
273 | * dropped the xa_lock, so we know the xa_state is stale and must be reset |
274 | * before use. |
275 | */ |
276 | static void dax_unlock_entry(struct xa_state *xas, void *entry) |
277 | { |
278 | void *old; |
279 | |
280 | BUG_ON(dax_is_locked(entry)); |
281 | xas_reset(xas); |
282 | xas_lock_irq(xas); |
283 | old = xas_store(xas, entry); |
284 | xas_unlock_irq(xas); |
285 | BUG_ON(!dax_is_locked(old)); |
286 | dax_wake_entry(xas, entry, mode: WAKE_NEXT); |
287 | } |
288 | |
289 | /* |
290 | * Return: The entry stored at this location before it was locked. |
291 | */ |
292 | static void *dax_lock_entry(struct xa_state *xas, void *entry) |
293 | { |
294 | unsigned long v = xa_to_value(entry); |
295 | return xas_store(xas, entry: xa_mk_value(v: v | DAX_LOCKED)); |
296 | } |
297 | |
298 | static unsigned long dax_entry_size(void *entry) |
299 | { |
300 | if (dax_is_zero_entry(entry)) |
301 | return 0; |
302 | else if (dax_is_empty_entry(entry)) |
303 | return 0; |
304 | else if (dax_is_pmd_entry(entry)) |
305 | return PMD_SIZE; |
306 | else |
307 | return PAGE_SIZE; |
308 | } |
309 | |
310 | static unsigned long dax_end_pfn(void *entry) |
311 | { |
312 | return dax_to_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE; |
313 | } |
314 | |
315 | /* |
316 | * Iterate through all mapped pfns represented by an entry, i.e. skip |
317 | * 'empty' and 'zero' entries. |
318 | */ |
319 | #define for_each_mapped_pfn(entry, pfn) \ |
320 | for (pfn = dax_to_pfn(entry); \ |
321 | pfn < dax_end_pfn(entry); pfn++) |
322 | |
323 | static inline bool dax_page_is_shared(struct page *page) |
324 | { |
325 | return page->mapping == PAGE_MAPPING_DAX_SHARED; |
326 | } |
327 | |
328 | /* |
329 | * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the |
330 | * refcount. |
331 | */ |
332 | static inline void dax_page_share_get(struct page *page) |
333 | { |
334 | if (page->mapping != PAGE_MAPPING_DAX_SHARED) { |
335 | /* |
336 | * Reset the index if the page was already mapped |
337 | * regularly before. |
338 | */ |
339 | if (page->mapping) |
340 | page->share = 1; |
341 | page->mapping = PAGE_MAPPING_DAX_SHARED; |
342 | } |
343 | page->share++; |
344 | } |
345 | |
346 | static inline unsigned long dax_page_share_put(struct page *page) |
347 | { |
348 | return --page->share; |
349 | } |
350 | |
351 | /* |
352 | * When it is called in dax_insert_entry(), the shared flag will indicate that |
353 | * whether this entry is shared by multiple files. If so, set the page->mapping |
354 | * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount. |
355 | */ |
356 | static void dax_associate_entry(void *entry, struct address_space *mapping, |
357 | struct vm_area_struct *vma, unsigned long address, bool shared) |
358 | { |
359 | unsigned long size = dax_entry_size(entry), pfn, index; |
360 | int i = 0; |
361 | |
362 | if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) |
363 | return; |
364 | |
365 | index = linear_page_index(vma, address: address & ~(size - 1)); |
366 | for_each_mapped_pfn(entry, pfn) { |
367 | struct page *page = pfn_to_page(pfn); |
368 | |
369 | if (shared) { |
370 | dax_page_share_get(page); |
371 | } else { |
372 | WARN_ON_ONCE(page->mapping); |
373 | page->mapping = mapping; |
374 | page->index = index + i++; |
375 | } |
376 | } |
377 | } |
378 | |
379 | static void dax_disassociate_entry(void *entry, struct address_space *mapping, |
380 | bool trunc) |
381 | { |
382 | unsigned long pfn; |
383 | |
384 | if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) |
385 | return; |
386 | |
387 | for_each_mapped_pfn(entry, pfn) { |
388 | struct page *page = pfn_to_page(pfn); |
389 | |
390 | WARN_ON_ONCE(trunc && page_ref_count(page) > 1); |
391 | if (dax_page_is_shared(page)) { |
392 | /* keep the shared flag if this page is still shared */ |
393 | if (dax_page_share_put(page) > 0) |
394 | continue; |
395 | } else |
396 | WARN_ON_ONCE(page->mapping && page->mapping != mapping); |
397 | page->mapping = NULL; |
398 | page->index = 0; |
399 | } |
400 | } |
401 | |
402 | static struct page *dax_busy_page(void *entry) |
403 | { |
404 | unsigned long pfn; |
405 | |
406 | for_each_mapped_pfn(entry, pfn) { |
407 | struct page *page = pfn_to_page(pfn); |
408 | |
409 | if (page_ref_count(page) > 1) |
410 | return page; |
411 | } |
412 | return NULL; |
413 | } |
414 | |
415 | /** |
416 | * dax_lock_folio - Lock the DAX entry corresponding to a folio |
417 | * @folio: The folio whose entry we want to lock |
418 | * |
419 | * Context: Process context. |
420 | * Return: A cookie to pass to dax_unlock_folio() or 0 if the entry could |
421 | * not be locked. |
422 | */ |
423 | dax_entry_t dax_lock_folio(struct folio *folio) |
424 | { |
425 | XA_STATE(xas, NULL, 0); |
426 | void *entry; |
427 | |
428 | /* Ensure folio->mapping isn't freed while we look at it */ |
429 | rcu_read_lock(); |
430 | for (;;) { |
431 | struct address_space *mapping = READ_ONCE(folio->mapping); |
432 | |
433 | entry = NULL; |
434 | if (!mapping || !dax_mapping(mapping)) |
435 | break; |
436 | |
437 | /* |
438 | * In the device-dax case there's no need to lock, a |
439 | * struct dev_pagemap pin is sufficient to keep the |
440 | * inode alive, and we assume we have dev_pagemap pin |
441 | * otherwise we would not have a valid pfn_to_page() |
442 | * translation. |
443 | */ |
444 | entry = (void *)~0UL; |
445 | if (S_ISCHR(mapping->host->i_mode)) |
446 | break; |
447 | |
448 | xas.xa = &mapping->i_pages; |
449 | xas_lock_irq(&xas); |
450 | if (mapping != folio->mapping) { |
451 | xas_unlock_irq(&xas); |
452 | continue; |
453 | } |
454 | xas_set(xas: &xas, index: folio->index); |
455 | entry = xas_load(&xas); |
456 | if (dax_is_locked(entry)) { |
457 | rcu_read_unlock(); |
458 | wait_entry_unlocked(xas: &xas, entry); |
459 | rcu_read_lock(); |
460 | continue; |
461 | } |
462 | dax_lock_entry(xas: &xas, entry); |
463 | xas_unlock_irq(&xas); |
464 | break; |
465 | } |
466 | rcu_read_unlock(); |
467 | return (dax_entry_t)entry; |
468 | } |
469 | |
470 | void dax_unlock_folio(struct folio *folio, dax_entry_t cookie) |
471 | { |
472 | struct address_space *mapping = folio->mapping; |
473 | XA_STATE(xas, &mapping->i_pages, folio->index); |
474 | |
475 | if (S_ISCHR(mapping->host->i_mode)) |
476 | return; |
477 | |
478 | dax_unlock_entry(xas: &xas, entry: (void *)cookie); |
479 | } |
480 | |
481 | /* |
482 | * dax_lock_mapping_entry - Lock the DAX entry corresponding to a mapping |
483 | * @mapping: the file's mapping whose entry we want to lock |
484 | * @index: the offset within this file |
485 | * @page: output the dax page corresponding to this dax entry |
486 | * |
487 | * Return: A cookie to pass to dax_unlock_mapping_entry() or 0 if the entry |
488 | * could not be locked. |
489 | */ |
490 | dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, pgoff_t index, |
491 | struct page **page) |
492 | { |
493 | XA_STATE(xas, NULL, 0); |
494 | void *entry; |
495 | |
496 | rcu_read_lock(); |
497 | for (;;) { |
498 | entry = NULL; |
499 | if (!dax_mapping(mapping)) |
500 | break; |
501 | |
502 | xas.xa = &mapping->i_pages; |
503 | xas_lock_irq(&xas); |
504 | xas_set(xas: &xas, index); |
505 | entry = xas_load(&xas); |
506 | if (dax_is_locked(entry)) { |
507 | rcu_read_unlock(); |
508 | wait_entry_unlocked(xas: &xas, entry); |
509 | rcu_read_lock(); |
510 | continue; |
511 | } |
512 | if (!entry || |
513 | dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { |
514 | /* |
515 | * Because we are looking for entry from file's mapping |
516 | * and index, so the entry may not be inserted for now, |
517 | * or even a zero/empty entry. We don't think this is |
518 | * an error case. So, return a special value and do |
519 | * not output @page. |
520 | */ |
521 | entry = (void *)~0UL; |
522 | } else { |
523 | *page = pfn_to_page(dax_to_pfn(entry)); |
524 | dax_lock_entry(xas: &xas, entry); |
525 | } |
526 | xas_unlock_irq(&xas); |
527 | break; |
528 | } |
529 | rcu_read_unlock(); |
530 | return (dax_entry_t)entry; |
531 | } |
532 | |
533 | void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index, |
534 | dax_entry_t cookie) |
535 | { |
536 | XA_STATE(xas, &mapping->i_pages, index); |
537 | |
538 | if (cookie == ~0UL) |
539 | return; |
540 | |
541 | dax_unlock_entry(xas: &xas, entry: (void *)cookie); |
542 | } |
543 | |
544 | /* |
545 | * Find page cache entry at given index. If it is a DAX entry, return it |
546 | * with the entry locked. If the page cache doesn't contain an entry at |
547 | * that index, add a locked empty entry. |
548 | * |
549 | * When requesting an entry with size DAX_PMD, grab_mapping_entry() will |
550 | * either return that locked entry or will return VM_FAULT_FALLBACK. |
551 | * This will happen if there are any PTE entries within the PMD range |
552 | * that we are requesting. |
553 | * |
554 | * We always favor PTE entries over PMD entries. There isn't a flow where we |
555 | * evict PTE entries in order to 'upgrade' them to a PMD entry. A PMD |
556 | * insertion will fail if it finds any PTE entries already in the tree, and a |
557 | * PTE insertion will cause an existing PMD entry to be unmapped and |
558 | * downgraded to PTE entries. This happens for both PMD zero pages as |
559 | * well as PMD empty entries. |
560 | * |
561 | * The exception to this downgrade path is for PMD entries that have |
562 | * real storage backing them. We will leave these real PMD entries in |
563 | * the tree, and PTE writes will simply dirty the entire PMD entry. |
564 | * |
565 | * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For |
566 | * persistent memory the benefit is doubtful. We can add that later if we can |
567 | * show it helps. |
568 | * |
569 | * On error, this function does not return an ERR_PTR. Instead it returns |
570 | * a VM_FAULT code, encoded as an xarray internal entry. The ERR_PTR values |
571 | * overlap with xarray value entries. |
572 | */ |
573 | static void *grab_mapping_entry(struct xa_state *xas, |
574 | struct address_space *mapping, unsigned int order) |
575 | { |
576 | unsigned long index = xas->xa_index; |
577 | bool pmd_downgrade; /* splitting PMD entry into PTE entries? */ |
578 | void *entry; |
579 | |
580 | retry: |
581 | pmd_downgrade = false; |
582 | xas_lock_irq(xas); |
583 | entry = get_unlocked_entry(xas, order); |
584 | |
585 | if (entry) { |
586 | if (dax_is_conflict(entry)) |
587 | goto fallback; |
588 | if (!xa_is_value(entry)) { |
589 | xas_set_err(xas, err: -EIO); |
590 | goto out_unlock; |
591 | } |
592 | |
593 | if (order == 0) { |
594 | if (dax_is_pmd_entry(entry) && |
595 | (dax_is_zero_entry(entry) || |
596 | dax_is_empty_entry(entry))) { |
597 | pmd_downgrade = true; |
598 | } |
599 | } |
600 | } |
601 | |
602 | if (pmd_downgrade) { |
603 | /* |
604 | * Make sure 'entry' remains valid while we drop |
605 | * the i_pages lock. |
606 | */ |
607 | dax_lock_entry(xas, entry); |
608 | |
609 | /* |
610 | * Besides huge zero pages the only other thing that gets |
611 | * downgraded are empty entries which don't need to be |
612 | * unmapped. |
613 | */ |
614 | if (dax_is_zero_entry(entry)) { |
615 | xas_unlock_irq(xas); |
616 | unmap_mapping_pages(mapping, |
617 | start: xas->xa_index & ~PG_PMD_COLOUR, |
618 | PG_PMD_NR, even_cows: false); |
619 | xas_reset(xas); |
620 | xas_lock_irq(xas); |
621 | } |
622 | |
623 | dax_disassociate_entry(entry, mapping, trunc: false); |
624 | xas_store(xas, NULL); /* undo the PMD join */ |
625 | dax_wake_entry(xas, entry, mode: WAKE_ALL); |
626 | mapping->nrpages -= PG_PMD_NR; |
627 | entry = NULL; |
628 | xas_set(xas, index); |
629 | } |
630 | |
631 | if (entry) { |
632 | dax_lock_entry(xas, entry); |
633 | } else { |
634 | unsigned long flags = DAX_EMPTY; |
635 | |
636 | if (order > 0) |
637 | flags |= DAX_PMD; |
638 | entry = dax_make_entry(pfn: pfn_to_pfn_t(pfn: 0), flags); |
639 | dax_lock_entry(xas, entry); |
640 | if (xas_error(xas)) |
641 | goto out_unlock; |
642 | mapping->nrpages += 1UL << order; |
643 | } |
644 | |
645 | out_unlock: |
646 | xas_unlock_irq(xas); |
647 | if (xas_nomem(xas, mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM)) |
648 | goto retry; |
649 | if (xas->xa_node == XA_ERROR(-ENOMEM)) |
650 | return xa_mk_internal(v: VM_FAULT_OOM); |
651 | if (xas_error(xas)) |
652 | return xa_mk_internal(v: VM_FAULT_SIGBUS); |
653 | return entry; |
654 | fallback: |
655 | xas_unlock_irq(xas); |
656 | return xa_mk_internal(v: VM_FAULT_FALLBACK); |
657 | } |
658 | |
659 | /** |
660 | * dax_layout_busy_page_range - find first pinned page in @mapping |
661 | * @mapping: address space to scan for a page with ref count > 1 |
662 | * @start: Starting offset. Page containing 'start' is included. |
663 | * @end: End offset. Page containing 'end' is included. If 'end' is LLONG_MAX, |
664 | * pages from 'start' till the end of file are included. |
665 | * |
666 | * DAX requires ZONE_DEVICE mapped pages. These pages are never |
667 | * 'onlined' to the page allocator so they are considered idle when |
668 | * page->count == 1. A filesystem uses this interface to determine if |
669 | * any page in the mapping is busy, i.e. for DMA, or other |
670 | * get_user_pages() usages. |
671 | * |
672 | * It is expected that the filesystem is holding locks to block the |
673 | * establishment of new mappings in this address_space. I.e. it expects |
674 | * to be able to run unmap_mapping_range() and subsequently not race |
675 | * mapping_mapped() becoming true. |
676 | */ |
677 | struct page *dax_layout_busy_page_range(struct address_space *mapping, |
678 | loff_t start, loff_t end) |
679 | { |
680 | void *entry; |
681 | unsigned int scanned = 0; |
682 | struct page *page = NULL; |
683 | pgoff_t start_idx = start >> PAGE_SHIFT; |
684 | pgoff_t end_idx; |
685 | XA_STATE(xas, &mapping->i_pages, start_idx); |
686 | |
687 | /* |
688 | * In the 'limited' case get_user_pages() for dax is disabled. |
689 | */ |
690 | if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) |
691 | return NULL; |
692 | |
693 | if (!dax_mapping(mapping) || !mapping_mapped(mapping)) |
694 | return NULL; |
695 | |
696 | /* If end == LLONG_MAX, all pages from start to till end of file */ |
697 | if (end == LLONG_MAX) |
698 | end_idx = ULONG_MAX; |
699 | else |
700 | end_idx = end >> PAGE_SHIFT; |
701 | /* |
702 | * If we race get_user_pages_fast() here either we'll see the |
703 | * elevated page count in the iteration and wait, or |
704 | * get_user_pages_fast() will see that the page it took a reference |
705 | * against is no longer mapped in the page tables and bail to the |
706 | * get_user_pages() slow path. The slow path is protected by |
707 | * pte_lock() and pmd_lock(). New references are not taken without |
708 | * holding those locks, and unmap_mapping_pages() will not zero the |
709 | * pte or pmd without holding the respective lock, so we are |
710 | * guaranteed to either see new references or prevent new |
711 | * references from being established. |
712 | */ |
713 | unmap_mapping_pages(mapping, start: start_idx, nr: end_idx - start_idx + 1, even_cows: 0); |
714 | |
715 | xas_lock_irq(&xas); |
716 | xas_for_each(&xas, entry, end_idx) { |
717 | if (WARN_ON_ONCE(!xa_is_value(entry))) |
718 | continue; |
719 | if (unlikely(dax_is_locked(entry))) |
720 | entry = get_unlocked_entry(xas: &xas, order: 0); |
721 | if (entry) |
722 | page = dax_busy_page(entry); |
723 | put_unlocked_entry(xas: &xas, entry, mode: WAKE_NEXT); |
724 | if (page) |
725 | break; |
726 | if (++scanned % XA_CHECK_SCHED) |
727 | continue; |
728 | |
729 | xas_pause(&xas); |
730 | xas_unlock_irq(&xas); |
731 | cond_resched(); |
732 | xas_lock_irq(&xas); |
733 | } |
734 | xas_unlock_irq(&xas); |
735 | return page; |
736 | } |
737 | EXPORT_SYMBOL_GPL(dax_layout_busy_page_range); |
738 | |
739 | struct page *dax_layout_busy_page(struct address_space *mapping) |
740 | { |
741 | return dax_layout_busy_page_range(mapping, 0, LLONG_MAX); |
742 | } |
743 | EXPORT_SYMBOL_GPL(dax_layout_busy_page); |
744 | |
745 | static int __dax_invalidate_entry(struct address_space *mapping, |
746 | pgoff_t index, bool trunc) |
747 | { |
748 | XA_STATE(xas, &mapping->i_pages, index); |
749 | int ret = 0; |
750 | void *entry; |
751 | |
752 | xas_lock_irq(&xas); |
753 | entry = get_unlocked_entry(xas: &xas, order: 0); |
754 | if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) |
755 | goto out; |
756 | if (!trunc && |
757 | (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY) || |
758 | xas_get_mark(&xas, PAGECACHE_TAG_TOWRITE))) |
759 | goto out; |
760 | dax_disassociate_entry(entry, mapping, trunc); |
761 | xas_store(&xas, NULL); |
762 | mapping->nrpages -= 1UL << dax_entry_order(entry); |
763 | ret = 1; |
764 | out: |
765 | put_unlocked_entry(xas: &xas, entry, mode: WAKE_ALL); |
766 | xas_unlock_irq(&xas); |
767 | return ret; |
768 | } |
769 | |
770 | static int __dax_clear_dirty_range(struct address_space *mapping, |
771 | pgoff_t start, pgoff_t end) |
772 | { |
773 | XA_STATE(xas, &mapping->i_pages, start); |
774 | unsigned int scanned = 0; |
775 | void *entry; |
776 | |
777 | xas_lock_irq(&xas); |
778 | xas_for_each(&xas, entry, end) { |
779 | entry = get_unlocked_entry(xas: &xas, order: 0); |
780 | xas_clear_mark(&xas, PAGECACHE_TAG_DIRTY); |
781 | xas_clear_mark(&xas, PAGECACHE_TAG_TOWRITE); |
782 | put_unlocked_entry(xas: &xas, entry, mode: WAKE_NEXT); |
783 | |
784 | if (++scanned % XA_CHECK_SCHED) |
785 | continue; |
786 | |
787 | xas_pause(&xas); |
788 | xas_unlock_irq(&xas); |
789 | cond_resched(); |
790 | xas_lock_irq(&xas); |
791 | } |
792 | xas_unlock_irq(&xas); |
793 | |
794 | return 0; |
795 | } |
796 | |
797 | /* |
798 | * Delete DAX entry at @index from @mapping. Wait for it |
799 | * to be unlocked before deleting it. |
800 | */ |
801 | int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) |
802 | { |
803 | int ret = __dax_invalidate_entry(mapping, index, trunc: true); |
804 | |
805 | /* |
806 | * This gets called from truncate / punch_hole path. As such, the caller |
807 | * must hold locks protecting against concurrent modifications of the |
808 | * page cache (usually fs-private i_mmap_sem for writing). Since the |
809 | * caller has seen a DAX entry for this index, we better find it |
810 | * at that index as well... |
811 | */ |
812 | WARN_ON_ONCE(!ret); |
813 | return ret; |
814 | } |
815 | |
816 | /* |
817 | * Invalidate DAX entry if it is clean. |
818 | */ |
819 | int dax_invalidate_mapping_entry_sync(struct address_space *mapping, |
820 | pgoff_t index) |
821 | { |
822 | return __dax_invalidate_entry(mapping, index, trunc: false); |
823 | } |
824 | |
825 | static pgoff_t dax_iomap_pgoff(const struct iomap *iomap, loff_t pos) |
826 | { |
827 | return PHYS_PFN(iomap->addr + (pos & PAGE_MASK) - iomap->offset); |
828 | } |
829 | |
830 | static int copy_cow_page_dax(struct vm_fault *vmf, const struct iomap_iter *iter) |
831 | { |
832 | pgoff_t pgoff = dax_iomap_pgoff(iomap: &iter->iomap, pos: iter->pos); |
833 | void *vto, *kaddr; |
834 | long rc; |
835 | int id; |
836 | |
837 | id = dax_read_lock(); |
838 | rc = dax_direct_access(dax_dev: iter->iomap.dax_dev, pgoff, nr_pages: 1, mode: DAX_ACCESS, |
839 | kaddr: &kaddr, NULL); |
840 | if (rc < 0) { |
841 | dax_read_unlock(id); |
842 | return rc; |
843 | } |
844 | vto = kmap_atomic(page: vmf->cow_page); |
845 | copy_user_page(to: vto, from: kaddr, vaddr: vmf->address, topage: vmf->cow_page); |
846 | kunmap_atomic(vto); |
847 | dax_read_unlock(id); |
848 | return 0; |
849 | } |
850 | |
851 | /* |
852 | * MAP_SYNC on a dax mapping guarantees dirty metadata is |
853 | * flushed on write-faults (non-cow), but not read-faults. |
854 | */ |
855 | static bool dax_fault_is_synchronous(const struct iomap_iter *iter, |
856 | struct vm_area_struct *vma) |
857 | { |
858 | return (iter->flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC) && |
859 | (iter->iomap.flags & IOMAP_F_DIRTY); |
860 | } |
861 | |
862 | /* |
863 | * By this point grab_mapping_entry() has ensured that we have a locked entry |
864 | * of the appropriate size so we don't have to worry about downgrading PMDs to |
865 | * PTEs. If we happen to be trying to insert a PTE and there is a PMD |
866 | * already in the tree, we will skip the insertion and just dirty the PMD as |
867 | * appropriate. |
868 | */ |
869 | static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, |
870 | const struct iomap_iter *iter, void *entry, pfn_t pfn, |
871 | unsigned long flags) |
872 | { |
873 | struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
874 | void *new_entry = dax_make_entry(pfn, flags); |
875 | bool write = iter->flags & IOMAP_WRITE; |
876 | bool dirty = write && !dax_fault_is_synchronous(iter, vma: vmf->vma); |
877 | bool shared = iter->iomap.flags & IOMAP_F_SHARED; |
878 | |
879 | if (dirty) |
880 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
881 | |
882 | if (shared || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) { |
883 | unsigned long index = xas->xa_index; |
884 | /* we are replacing a zero page with block mapping */ |
885 | if (dax_is_pmd_entry(entry)) |
886 | unmap_mapping_pages(mapping, start: index & ~PG_PMD_COLOUR, |
887 | PG_PMD_NR, even_cows: false); |
888 | else /* pte entry */ |
889 | unmap_mapping_pages(mapping, start: index, nr: 1, even_cows: false); |
890 | } |
891 | |
892 | xas_reset(xas); |
893 | xas_lock_irq(xas); |
894 | if (shared || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { |
895 | void *old; |
896 | |
897 | dax_disassociate_entry(entry, mapping, trunc: false); |
898 | dax_associate_entry(entry: new_entry, mapping, vma: vmf->vma, address: vmf->address, |
899 | shared); |
900 | /* |
901 | * Only swap our new entry into the page cache if the current |
902 | * entry is a zero page or an empty entry. If a normal PTE or |
903 | * PMD entry is already in the cache, we leave it alone. This |
904 | * means that if we are trying to insert a PTE and the |
905 | * existing entry is a PMD, we will just leave the PMD in the |
906 | * tree and dirty it if necessary. |
907 | */ |
908 | old = dax_lock_entry(xas, entry: new_entry); |
909 | WARN_ON_ONCE(old != xa_mk_value(xa_to_value(entry) | |
910 | DAX_LOCKED)); |
911 | entry = new_entry; |
912 | } else { |
913 | xas_load(xas); /* Walk the xa_state */ |
914 | } |
915 | |
916 | if (dirty) |
917 | xas_set_mark(xas, PAGECACHE_TAG_DIRTY); |
918 | |
919 | if (write && shared) |
920 | xas_set_mark(xas, PAGECACHE_TAG_TOWRITE); |
921 | |
922 | xas_unlock_irq(xas); |
923 | return entry; |
924 | } |
925 | |
926 | static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, |
927 | struct address_space *mapping, void *entry) |
928 | { |
929 | unsigned long pfn, index, count, end; |
930 | long ret = 0; |
931 | struct vm_area_struct *vma; |
932 | |
933 | /* |
934 | * A page got tagged dirty in DAX mapping? Something is seriously |
935 | * wrong. |
936 | */ |
937 | if (WARN_ON(!xa_is_value(entry))) |
938 | return -EIO; |
939 | |
940 | if (unlikely(dax_is_locked(entry))) { |
941 | void *old_entry = entry; |
942 | |
943 | entry = get_unlocked_entry(xas, order: 0); |
944 | |
945 | /* Entry got punched out / reallocated? */ |
946 | if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) |
947 | goto put_unlocked; |
948 | /* |
949 | * Entry got reallocated elsewhere? No need to writeback. |
950 | * We have to compare pfns as we must not bail out due to |
951 | * difference in lockbit or entry type. |
952 | */ |
953 | if (dax_to_pfn(entry: old_entry) != dax_to_pfn(entry)) |
954 | goto put_unlocked; |
955 | if (WARN_ON_ONCE(dax_is_empty_entry(entry) || |
956 | dax_is_zero_entry(entry))) { |
957 | ret = -EIO; |
958 | goto put_unlocked; |
959 | } |
960 | |
961 | /* Another fsync thread may have already done this entry */ |
962 | if (!xas_get_mark(xas, PAGECACHE_TAG_TOWRITE)) |
963 | goto put_unlocked; |
964 | } |
965 | |
966 | /* Lock the entry to serialize with page faults */ |
967 | dax_lock_entry(xas, entry); |
968 | |
969 | /* |
970 | * We can clear the tag now but we have to be careful so that concurrent |
971 | * dax_writeback_one() calls for the same index cannot finish before we |
972 | * actually flush the caches. This is achieved as the calls will look |
973 | * at the entry only under the i_pages lock and once they do that |
974 | * they will see the entry locked and wait for it to unlock. |
975 | */ |
976 | xas_clear_mark(xas, PAGECACHE_TAG_TOWRITE); |
977 | xas_unlock_irq(xas); |
978 | |
979 | /* |
980 | * If dax_writeback_mapping_range() was given a wbc->range_start |
981 | * in the middle of a PMD, the 'index' we use needs to be |
982 | * aligned to the start of the PMD. |
983 | * This allows us to flush for PMD_SIZE and not have to worry about |
984 | * partial PMD writebacks. |
985 | */ |
986 | pfn = dax_to_pfn(entry); |
987 | count = 1UL << dax_entry_order(entry); |
988 | index = xas->xa_index & ~(count - 1); |
989 | end = index + count - 1; |
990 | |
991 | /* Walk all mappings of a given index of a file and writeprotect them */ |
992 | i_mmap_lock_read(mapping); |
993 | vma_interval_tree_foreach(vma, &mapping->i_mmap, index, end) { |
994 | pfn_mkclean_range(pfn, nr_pages: count, pgoff: index, vma); |
995 | cond_resched(); |
996 | } |
997 | i_mmap_unlock_read(mapping); |
998 | |
999 | dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size: count * PAGE_SIZE); |
1000 | /* |
1001 | * After we have flushed the cache, we can clear the dirty tag. There |
1002 | * cannot be new dirty data in the pfn after the flush has completed as |
1003 | * the pfn mappings are writeprotected and fault waits for mapping |
1004 | * entry lock. |
1005 | */ |
1006 | xas_reset(xas); |
1007 | xas_lock_irq(xas); |
1008 | xas_store(xas, entry); |
1009 | xas_clear_mark(xas, PAGECACHE_TAG_DIRTY); |
1010 | dax_wake_entry(xas, entry, mode: WAKE_NEXT); |
1011 | |
1012 | trace_dax_writeback_one(inode: mapping->host, pgoff: index, pglen: count); |
1013 | return ret; |
1014 | |
1015 | put_unlocked: |
1016 | put_unlocked_entry(xas, entry, mode: WAKE_NEXT); |
1017 | return ret; |
1018 | } |
1019 | |
1020 | /* |
1021 | * Flush the mapping to the persistent domain within the byte range of [start, |
1022 | * end]. This is required by data integrity operations to ensure file data is |
1023 | * on persistent storage prior to completion of the operation. |
1024 | */ |
1025 | int dax_writeback_mapping_range(struct address_space *mapping, |
1026 | struct dax_device *dax_dev, struct writeback_control *wbc) |
1027 | { |
1028 | XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT); |
1029 | struct inode *inode = mapping->host; |
1030 | pgoff_t end_index = wbc->range_end >> PAGE_SHIFT; |
1031 | void *entry; |
1032 | int ret = 0; |
1033 | unsigned int scanned = 0; |
1034 | |
1035 | if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) |
1036 | return -EIO; |
1037 | |
1038 | if (mapping_empty(mapping) || wbc->sync_mode != WB_SYNC_ALL) |
1039 | return 0; |
1040 | |
1041 | trace_dax_writeback_range(inode, start_index: xas.xa_index, end_index); |
1042 | |
1043 | tag_pages_for_writeback(mapping, start: xas.xa_index, end: end_index); |
1044 | |
1045 | xas_lock_irq(&xas); |
1046 | xas_for_each_marked(&xas, entry, end_index, PAGECACHE_TAG_TOWRITE) { |
1047 | ret = dax_writeback_one(xas: &xas, dax_dev, mapping, entry); |
1048 | if (ret < 0) { |
1049 | mapping_set_error(mapping, error: ret); |
1050 | break; |
1051 | } |
1052 | if (++scanned % XA_CHECK_SCHED) |
1053 | continue; |
1054 | |
1055 | xas_pause(&xas); |
1056 | xas_unlock_irq(&xas); |
1057 | cond_resched(); |
1058 | xas_lock_irq(&xas); |
1059 | } |
1060 | xas_unlock_irq(&xas); |
1061 | trace_dax_writeback_range_done(inode, start_index: xas.xa_index, end_index); |
1062 | return ret; |
1063 | } |
1064 | EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); |
1065 | |
1066 | static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos, |
1067 | size_t size, void **kaddr, pfn_t *pfnp) |
1068 | { |
1069 | pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); |
1070 | int id, rc = 0; |
1071 | long length; |
1072 | |
1073 | id = dax_read_lock(); |
1074 | length = dax_direct_access(dax_dev: iomap->dax_dev, pgoff, PHYS_PFN(size), |
1075 | mode: DAX_ACCESS, kaddr, pfn: pfnp); |
1076 | if (length < 0) { |
1077 | rc = length; |
1078 | goto out; |
1079 | } |
1080 | if (!pfnp) |
1081 | goto out_check_addr; |
1082 | rc = -EINVAL; |
1083 | if (PFN_PHYS(length) < size) |
1084 | goto out; |
1085 | if (pfn_t_to_pfn(pfn: *pfnp) & (PHYS_PFN(size)-1)) |
1086 | goto out; |
1087 | /* For larger pages we need devmap */ |
1088 | if (length > 1 && !pfn_t_devmap(pfn: *pfnp)) |
1089 | goto out; |
1090 | rc = 0; |
1091 | |
1092 | out_check_addr: |
1093 | if (!kaddr) |
1094 | goto out; |
1095 | if (!*kaddr) |
1096 | rc = -EFAULT; |
1097 | out: |
1098 | dax_read_unlock(id); |
1099 | return rc; |
1100 | } |
1101 | |
1102 | /** |
1103 | * dax_iomap_copy_around - Prepare for an unaligned write to a shared/cow page |
1104 | * by copying the data before and after the range to be written. |
1105 | * @pos: address to do copy from. |
1106 | * @length: size of copy operation. |
1107 | * @align_size: aligned w.r.t align_size (either PMD_SIZE or PAGE_SIZE) |
1108 | * @srcmap: iomap srcmap |
1109 | * @daddr: destination address to copy to. |
1110 | * |
1111 | * This can be called from two places. Either during DAX write fault (page |
1112 | * aligned), to copy the length size data to daddr. Or, while doing normal DAX |
1113 | * write operation, dax_iomap_iter() might call this to do the copy of either |
1114 | * start or end unaligned address. In the latter case the rest of the copy of |
1115 | * aligned ranges is taken care by dax_iomap_iter() itself. |
1116 | * If the srcmap contains invalid data, such as HOLE and UNWRITTEN, zero the |
1117 | * area to make sure no old data remains. |
1118 | */ |
1119 | static int dax_iomap_copy_around(loff_t pos, uint64_t length, size_t align_size, |
1120 | const struct iomap *srcmap, void *daddr) |
1121 | { |
1122 | loff_t head_off = pos & (align_size - 1); |
1123 | size_t size = ALIGN(head_off + length, align_size); |
1124 | loff_t end = pos + length; |
1125 | loff_t pg_end = round_up(end, align_size); |
1126 | /* copy_all is usually in page fault case */ |
1127 | bool copy_all = head_off == 0 && end == pg_end; |
1128 | /* zero the edges if srcmap is a HOLE or IOMAP_UNWRITTEN */ |
1129 | bool zero_edge = srcmap->flags & IOMAP_F_SHARED || |
1130 | srcmap->type == IOMAP_UNWRITTEN; |
1131 | void *saddr = NULL; |
1132 | int ret = 0; |
1133 | |
1134 | if (!zero_edge) { |
1135 | ret = dax_iomap_direct_access(iomap: srcmap, pos, size, kaddr: &saddr, NULL); |
1136 | if (ret) |
1137 | return dax_mem2blk_err(err: ret); |
1138 | } |
1139 | |
1140 | if (copy_all) { |
1141 | if (zero_edge) |
1142 | memset(daddr, 0, size); |
1143 | else |
1144 | ret = copy_mc_to_kernel(to: daddr, from: saddr, len: length); |
1145 | goto out; |
1146 | } |
1147 | |
1148 | /* Copy the head part of the range */ |
1149 | if (head_off) { |
1150 | if (zero_edge) |
1151 | memset(daddr, 0, head_off); |
1152 | else { |
1153 | ret = copy_mc_to_kernel(to: daddr, from: saddr, len: head_off); |
1154 | if (ret) |
1155 | return -EIO; |
1156 | } |
1157 | } |
1158 | |
1159 | /* Copy the tail part of the range */ |
1160 | if (end < pg_end) { |
1161 | loff_t tail_off = head_off + length; |
1162 | loff_t tail_len = pg_end - end; |
1163 | |
1164 | if (zero_edge) |
1165 | memset(daddr + tail_off, 0, tail_len); |
1166 | else { |
1167 | ret = copy_mc_to_kernel(to: daddr + tail_off, |
1168 | from: saddr + tail_off, len: tail_len); |
1169 | if (ret) |
1170 | return -EIO; |
1171 | } |
1172 | } |
1173 | out: |
1174 | if (zero_edge) |
1175 | dax_flush(dax_dev: srcmap->dax_dev, addr: daddr, size); |
1176 | return ret ? -EIO : 0; |
1177 | } |
1178 | |
1179 | /* |
1180 | * The user has performed a load from a hole in the file. Allocating a new |
1181 | * page in the file would cause excessive storage usage for workloads with |
1182 | * sparse files. Instead we insert a read-only mapping of the 4k zero page. |
1183 | * If this page is ever written to we will re-fault and change the mapping to |
1184 | * point to real DAX storage instead. |
1185 | */ |
1186 | static vm_fault_t dax_load_hole(struct xa_state *xas, struct vm_fault *vmf, |
1187 | const struct iomap_iter *iter, void **entry) |
1188 | { |
1189 | struct inode *inode = iter->inode; |
1190 | unsigned long vaddr = vmf->address; |
1191 | pfn_t pfn = pfn_to_pfn_t(pfn: my_zero_pfn(addr: vaddr)); |
1192 | vm_fault_t ret; |
1193 | |
1194 | *entry = dax_insert_entry(xas, vmf, iter, entry: *entry, pfn, DAX_ZERO_PAGE); |
1195 | |
1196 | ret = vmf_insert_mixed(vma: vmf->vma, addr: vaddr, pfn); |
1197 | trace_dax_load_hole(inode, vmf, result: ret); |
1198 | return ret; |
1199 | } |
1200 | |
1201 | #ifdef CONFIG_FS_DAX_PMD |
1202 | static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, |
1203 | const struct iomap_iter *iter, void **entry) |
1204 | { |
1205 | struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
1206 | unsigned long pmd_addr = vmf->address & PMD_MASK; |
1207 | struct vm_area_struct *vma = vmf->vma; |
1208 | struct inode *inode = mapping->host; |
1209 | pgtable_t pgtable = NULL; |
1210 | struct page *zero_page; |
1211 | spinlock_t *ptl; |
1212 | pmd_t pmd_entry; |
1213 | pfn_t pfn; |
1214 | |
1215 | zero_page = mm_get_huge_zero_page(mm: vmf->vma->vm_mm); |
1216 | |
1217 | if (unlikely(!zero_page)) |
1218 | goto fallback; |
1219 | |
1220 | pfn = page_to_pfn_t(page: zero_page); |
1221 | *entry = dax_insert_entry(xas, vmf, iter, entry: *entry, pfn, |
1222 | DAX_PMD | DAX_ZERO_PAGE); |
1223 | |
1224 | if (arch_needs_pgtable_deposit()) { |
1225 | pgtable = pte_alloc_one(vma->vm_mm); |
1226 | if (!pgtable) |
1227 | return VM_FAULT_OOM; |
1228 | } |
1229 | |
1230 | ptl = pmd_lock(mm: vmf->vma->vm_mm, pmd: vmf->pmd); |
1231 | if (!pmd_none(pmd: *(vmf->pmd))) { |
1232 | spin_unlock(lock: ptl); |
1233 | goto fallback; |
1234 | } |
1235 | |
1236 | if (pgtable) { |
1237 | pgtable_trans_huge_deposit(mm: vma->vm_mm, pmdp: vmf->pmd, pgtable); |
1238 | mm_inc_nr_ptes(mm: vma->vm_mm); |
1239 | } |
1240 | pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); |
1241 | pmd_entry = pmd_mkhuge(pmd: pmd_entry); |
1242 | set_pmd_at(mm: vmf->vma->vm_mm, addr: pmd_addr, pmdp: vmf->pmd, pmd: pmd_entry); |
1243 | spin_unlock(lock: ptl); |
1244 | trace_dax_pmd_load_hole(inode, vmf, zero_page, radix_entry: *entry); |
1245 | return VM_FAULT_NOPAGE; |
1246 | |
1247 | fallback: |
1248 | if (pgtable) |
1249 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
1250 | trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, radix_entry: *entry); |
1251 | return VM_FAULT_FALLBACK; |
1252 | } |
1253 | #else |
1254 | static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, |
1255 | const struct iomap_iter *iter, void **entry) |
1256 | { |
1257 | return VM_FAULT_FALLBACK; |
1258 | } |
1259 | #endif /* CONFIG_FS_DAX_PMD */ |
1260 | |
1261 | static s64 dax_unshare_iter(struct iomap_iter *iter) |
1262 | { |
1263 | struct iomap *iomap = &iter->iomap; |
1264 | const struct iomap *srcmap = iomap_iter_srcmap(i: iter); |
1265 | loff_t pos = iter->pos; |
1266 | loff_t length = iomap_length(iter); |
1267 | int id = 0; |
1268 | s64 ret = 0; |
1269 | void *daddr = NULL, *saddr = NULL; |
1270 | |
1271 | /* don't bother with blocks that are not shared to start with */ |
1272 | if (!(iomap->flags & IOMAP_F_SHARED)) |
1273 | return length; |
1274 | |
1275 | id = dax_read_lock(); |
1276 | ret = dax_iomap_direct_access(iomap, pos, size: length, kaddr: &daddr, NULL); |
1277 | if (ret < 0) |
1278 | goto out_unlock; |
1279 | |
1280 | /* zero the distance if srcmap is HOLE or UNWRITTEN */ |
1281 | if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) { |
1282 | memset(daddr, 0, length); |
1283 | dax_flush(dax_dev: iomap->dax_dev, addr: daddr, size: length); |
1284 | ret = length; |
1285 | goto out_unlock; |
1286 | } |
1287 | |
1288 | ret = dax_iomap_direct_access(iomap: srcmap, pos, size: length, kaddr: &saddr, NULL); |
1289 | if (ret < 0) |
1290 | goto out_unlock; |
1291 | |
1292 | if (copy_mc_to_kernel(to: daddr, from: saddr, len: length) == 0) |
1293 | ret = length; |
1294 | else |
1295 | ret = -EIO; |
1296 | |
1297 | out_unlock: |
1298 | dax_read_unlock(id); |
1299 | return dax_mem2blk_err(err: ret); |
1300 | } |
1301 | |
1302 | int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len, |
1303 | const struct iomap_ops *ops) |
1304 | { |
1305 | struct iomap_iter iter = { |
1306 | .inode = inode, |
1307 | .pos = pos, |
1308 | .len = len, |
1309 | .flags = IOMAP_WRITE | IOMAP_UNSHARE | IOMAP_DAX, |
1310 | }; |
1311 | int ret; |
1312 | |
1313 | while ((ret = iomap_iter(iter: &iter, ops)) > 0) |
1314 | iter.processed = dax_unshare_iter(iter: &iter); |
1315 | return ret; |
1316 | } |
1317 | EXPORT_SYMBOL_GPL(dax_file_unshare); |
1318 | |
1319 | static int dax_memzero(struct iomap_iter *iter, loff_t pos, size_t size) |
1320 | { |
1321 | const struct iomap *iomap = &iter->iomap; |
1322 | const struct iomap *srcmap = iomap_iter_srcmap(i: iter); |
1323 | unsigned offset = offset_in_page(pos); |
1324 | pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); |
1325 | void *kaddr; |
1326 | long ret; |
1327 | |
1328 | ret = dax_direct_access(dax_dev: iomap->dax_dev, pgoff, nr_pages: 1, mode: DAX_ACCESS, kaddr: &kaddr, |
1329 | NULL); |
1330 | if (ret < 0) |
1331 | return dax_mem2blk_err(err: ret); |
1332 | |
1333 | memset(kaddr + offset, 0, size); |
1334 | if (iomap->flags & IOMAP_F_SHARED) |
1335 | ret = dax_iomap_copy_around(pos, length: size, PAGE_SIZE, srcmap, |
1336 | daddr: kaddr); |
1337 | else |
1338 | dax_flush(dax_dev: iomap->dax_dev, addr: kaddr + offset, size); |
1339 | return ret; |
1340 | } |
1341 | |
1342 | static s64 dax_zero_iter(struct iomap_iter *iter, bool *did_zero) |
1343 | { |
1344 | const struct iomap *iomap = &iter->iomap; |
1345 | const struct iomap *srcmap = iomap_iter_srcmap(i: iter); |
1346 | loff_t pos = iter->pos; |
1347 | u64 length = iomap_length(iter); |
1348 | s64 written = 0; |
1349 | |
1350 | /* already zeroed? we're done. */ |
1351 | if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) |
1352 | return length; |
1353 | |
1354 | /* |
1355 | * invalidate the pages whose sharing state is to be changed |
1356 | * because of CoW. |
1357 | */ |
1358 | if (iomap->flags & IOMAP_F_SHARED) |
1359 | invalidate_inode_pages2_range(mapping: iter->inode->i_mapping, |
1360 | start: pos >> PAGE_SHIFT, |
1361 | end: (pos + length - 1) >> PAGE_SHIFT); |
1362 | |
1363 | do { |
1364 | unsigned offset = offset_in_page(pos); |
1365 | unsigned size = min_t(u64, PAGE_SIZE - offset, length); |
1366 | pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); |
1367 | long rc; |
1368 | int id; |
1369 | |
1370 | id = dax_read_lock(); |
1371 | if (IS_ALIGNED(pos, PAGE_SIZE) && size == PAGE_SIZE) |
1372 | rc = dax_zero_page_range(dax_dev: iomap->dax_dev, pgoff, nr_pages: 1); |
1373 | else |
1374 | rc = dax_memzero(iter, pos, size); |
1375 | dax_read_unlock(id); |
1376 | |
1377 | if (rc < 0) |
1378 | return rc; |
1379 | pos += size; |
1380 | length -= size; |
1381 | written += size; |
1382 | } while (length > 0); |
1383 | |
1384 | if (did_zero) |
1385 | *did_zero = true; |
1386 | return written; |
1387 | } |
1388 | |
1389 | int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, |
1390 | const struct iomap_ops *ops) |
1391 | { |
1392 | struct iomap_iter iter = { |
1393 | .inode = inode, |
1394 | .pos = pos, |
1395 | .len = len, |
1396 | .flags = IOMAP_DAX | IOMAP_ZERO, |
1397 | }; |
1398 | int ret; |
1399 | |
1400 | while ((ret = iomap_iter(iter: &iter, ops)) > 0) |
1401 | iter.processed = dax_zero_iter(iter: &iter, did_zero); |
1402 | return ret; |
1403 | } |
1404 | EXPORT_SYMBOL_GPL(dax_zero_range); |
1405 | |
1406 | int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, |
1407 | const struct iomap_ops *ops) |
1408 | { |
1409 | unsigned int blocksize = i_blocksize(node: inode); |
1410 | unsigned int off = pos & (blocksize - 1); |
1411 | |
1412 | /* Block boundary? Nothing to do */ |
1413 | if (!off) |
1414 | return 0; |
1415 | return dax_zero_range(inode, pos, blocksize - off, did_zero, ops); |
1416 | } |
1417 | EXPORT_SYMBOL_GPL(dax_truncate_page); |
1418 | |
1419 | static loff_t dax_iomap_iter(const struct iomap_iter *iomi, |
1420 | struct iov_iter *iter) |
1421 | { |
1422 | const struct iomap *iomap = &iomi->iomap; |
1423 | const struct iomap *srcmap = iomap_iter_srcmap(i: iomi); |
1424 | loff_t length = iomap_length(iter: iomi); |
1425 | loff_t pos = iomi->pos; |
1426 | struct dax_device *dax_dev = iomap->dax_dev; |
1427 | loff_t end = pos + length, done = 0; |
1428 | bool write = iov_iter_rw(i: iter) == WRITE; |
1429 | bool cow = write && iomap->flags & IOMAP_F_SHARED; |
1430 | ssize_t ret = 0; |
1431 | size_t xfer; |
1432 | int id; |
1433 | |
1434 | if (!write) { |
1435 | end = min(end, i_size_read(iomi->inode)); |
1436 | if (pos >= end) |
1437 | return 0; |
1438 | |
1439 | if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) |
1440 | return iov_iter_zero(min(length, end - pos), iter); |
1441 | } |
1442 | |
1443 | /* |
1444 | * In DAX mode, enforce either pure overwrites of written extents, or |
1445 | * writes to unwritten extents as part of a copy-on-write operation. |
1446 | */ |
1447 | if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED && |
1448 | !(iomap->flags & IOMAP_F_SHARED))) |
1449 | return -EIO; |
1450 | |
1451 | /* |
1452 | * Write can allocate block for an area which has a hole page mapped |
1453 | * into page tables. We have to tear down these mappings so that data |
1454 | * written by write(2) is visible in mmap. |
1455 | */ |
1456 | if (iomap->flags & IOMAP_F_NEW || cow) { |
1457 | /* |
1458 | * Filesystem allows CoW on non-shared extents. The src extents |
1459 | * may have been mmapped with dirty mark before. To be able to |
1460 | * invalidate its dax entries, we need to clear the dirty mark |
1461 | * in advance. |
1462 | */ |
1463 | if (cow) |
1464 | __dax_clear_dirty_range(mapping: iomi->inode->i_mapping, |
1465 | start: pos >> PAGE_SHIFT, |
1466 | end: (end - 1) >> PAGE_SHIFT); |
1467 | invalidate_inode_pages2_range(mapping: iomi->inode->i_mapping, |
1468 | start: pos >> PAGE_SHIFT, |
1469 | end: (end - 1) >> PAGE_SHIFT); |
1470 | } |
1471 | |
1472 | id = dax_read_lock(); |
1473 | while (pos < end) { |
1474 | unsigned offset = pos & (PAGE_SIZE - 1); |
1475 | const size_t size = ALIGN(length + offset, PAGE_SIZE); |
1476 | pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); |
1477 | ssize_t map_len; |
1478 | bool recovery = false; |
1479 | void *kaddr; |
1480 | |
1481 | if (fatal_signal_pending(current)) { |
1482 | ret = -EINTR; |
1483 | break; |
1484 | } |
1485 | |
1486 | map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), |
1487 | mode: DAX_ACCESS, kaddr: &kaddr, NULL); |
1488 | if (map_len == -EHWPOISON && iov_iter_rw(i: iter) == WRITE) { |
1489 | map_len = dax_direct_access(dax_dev, pgoff, |
1490 | PHYS_PFN(size), mode: DAX_RECOVERY_WRITE, |
1491 | kaddr: &kaddr, NULL); |
1492 | if (map_len > 0) |
1493 | recovery = true; |
1494 | } |
1495 | if (map_len < 0) { |
1496 | ret = dax_mem2blk_err(err: map_len); |
1497 | break; |
1498 | } |
1499 | |
1500 | if (cow) { |
1501 | ret = dax_iomap_copy_around(pos, length, PAGE_SIZE, |
1502 | srcmap, daddr: kaddr); |
1503 | if (ret) |
1504 | break; |
1505 | } |
1506 | |
1507 | map_len = PFN_PHYS(map_len); |
1508 | kaddr += offset; |
1509 | map_len -= offset; |
1510 | if (map_len > end - pos) |
1511 | map_len = end - pos; |
1512 | |
1513 | if (recovery) |
1514 | xfer = dax_recovery_write(dax_dev, pgoff, addr: kaddr, |
1515 | bytes: map_len, i: iter); |
1516 | else if (write) |
1517 | xfer = dax_copy_from_iter(dax_dev, pgoff, addr: kaddr, |
1518 | bytes: map_len, i: iter); |
1519 | else |
1520 | xfer = dax_copy_to_iter(dax_dev, pgoff, addr: kaddr, |
1521 | bytes: map_len, i: iter); |
1522 | |
1523 | pos += xfer; |
1524 | length -= xfer; |
1525 | done += xfer; |
1526 | |
1527 | if (xfer == 0) |
1528 | ret = -EFAULT; |
1529 | if (xfer < map_len) |
1530 | break; |
1531 | } |
1532 | dax_read_unlock(id); |
1533 | |
1534 | return done ? done : ret; |
1535 | } |
1536 | |
1537 | /** |
1538 | * dax_iomap_rw - Perform I/O to a DAX file |
1539 | * @iocb: The control block for this I/O |
1540 | * @iter: The addresses to do I/O from or to |
1541 | * @ops: iomap ops passed from the file system |
1542 | * |
1543 | * This function performs read and write operations to directly mapped |
1544 | * persistent memory. The callers needs to take care of read/write exclusion |
1545 | * and evicting any page cache pages in the region under I/O. |
1546 | */ |
1547 | ssize_t |
1548 | dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, |
1549 | const struct iomap_ops *ops) |
1550 | { |
1551 | struct iomap_iter iomi = { |
1552 | .inode = iocb->ki_filp->f_mapping->host, |
1553 | .pos = iocb->ki_pos, |
1554 | .len = iov_iter_count(i: iter), |
1555 | .flags = IOMAP_DAX, |
1556 | }; |
1557 | loff_t done = 0; |
1558 | int ret; |
1559 | |
1560 | if (!iomi.len) |
1561 | return 0; |
1562 | |
1563 | if (iov_iter_rw(i: iter) == WRITE) { |
1564 | lockdep_assert_held_write(&iomi.inode->i_rwsem); |
1565 | iomi.flags |= IOMAP_WRITE; |
1566 | } else { |
1567 | lockdep_assert_held(&iomi.inode->i_rwsem); |
1568 | } |
1569 | |
1570 | if (iocb->ki_flags & IOCB_NOWAIT) |
1571 | iomi.flags |= IOMAP_NOWAIT; |
1572 | |
1573 | while ((ret = iomap_iter(iter: &iomi, ops)) > 0) |
1574 | iomi.processed = dax_iomap_iter(iomi: &iomi, iter); |
1575 | |
1576 | done = iomi.pos - iocb->ki_pos; |
1577 | iocb->ki_pos = iomi.pos; |
1578 | return done ? done : ret; |
1579 | } |
1580 | EXPORT_SYMBOL_GPL(dax_iomap_rw); |
1581 | |
1582 | static vm_fault_t dax_fault_return(int error) |
1583 | { |
1584 | if (error == 0) |
1585 | return VM_FAULT_NOPAGE; |
1586 | return vmf_error(err: error); |
1587 | } |
1588 | |
1589 | /* |
1590 | * When handling a synchronous page fault and the inode need a fsync, we can |
1591 | * insert the PTE/PMD into page tables only after that fsync happened. Skip |
1592 | * insertion for now and return the pfn so that caller can insert it after the |
1593 | * fsync is done. |
1594 | */ |
1595 | static vm_fault_t dax_fault_synchronous_pfnp(pfn_t *pfnp, pfn_t pfn) |
1596 | { |
1597 | if (WARN_ON_ONCE(!pfnp)) |
1598 | return VM_FAULT_SIGBUS; |
1599 | *pfnp = pfn; |
1600 | return VM_FAULT_NEEDDSYNC; |
1601 | } |
1602 | |
1603 | static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf, |
1604 | const struct iomap_iter *iter) |
1605 | { |
1606 | vm_fault_t ret; |
1607 | int error = 0; |
1608 | |
1609 | switch (iter->iomap.type) { |
1610 | case IOMAP_HOLE: |
1611 | case IOMAP_UNWRITTEN: |
1612 | clear_user_highpage(page: vmf->cow_page, vaddr: vmf->address); |
1613 | break; |
1614 | case IOMAP_MAPPED: |
1615 | error = copy_cow_page_dax(vmf, iter); |
1616 | break; |
1617 | default: |
1618 | WARN_ON_ONCE(1); |
1619 | error = -EIO; |
1620 | break; |
1621 | } |
1622 | |
1623 | if (error) |
1624 | return dax_fault_return(error); |
1625 | |
1626 | __SetPageUptodate(page: vmf->cow_page); |
1627 | ret = finish_fault(vmf); |
1628 | if (!ret) |
1629 | return VM_FAULT_DONE_COW; |
1630 | return ret; |
1631 | } |
1632 | |
1633 | /** |
1634 | * dax_fault_iter - Common actor to handle pfn insertion in PTE/PMD fault. |
1635 | * @vmf: vm fault instance |
1636 | * @iter: iomap iter |
1637 | * @pfnp: pfn to be returned |
1638 | * @xas: the dax mapping tree of a file |
1639 | * @entry: an unlocked dax entry to be inserted |
1640 | * @pmd: distinguish whether it is a pmd fault |
1641 | */ |
1642 | static vm_fault_t dax_fault_iter(struct vm_fault *vmf, |
1643 | const struct iomap_iter *iter, pfn_t *pfnp, |
1644 | struct xa_state *xas, void **entry, bool pmd) |
1645 | { |
1646 | const struct iomap *iomap = &iter->iomap; |
1647 | const struct iomap *srcmap = iomap_iter_srcmap(i: iter); |
1648 | size_t size = pmd ? PMD_SIZE : PAGE_SIZE; |
1649 | loff_t pos = (loff_t)xas->xa_index << PAGE_SHIFT; |
1650 | bool write = iter->flags & IOMAP_WRITE; |
1651 | unsigned long entry_flags = pmd ? DAX_PMD : 0; |
1652 | int err = 0; |
1653 | pfn_t pfn; |
1654 | void *kaddr; |
1655 | |
1656 | if (!pmd && vmf->cow_page) |
1657 | return dax_fault_cow_page(vmf, iter); |
1658 | |
1659 | /* if we are reading UNWRITTEN and HOLE, return a hole. */ |
1660 | if (!write && |
1661 | (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) { |
1662 | if (!pmd) |
1663 | return dax_load_hole(xas, vmf, iter, entry); |
1664 | return dax_pmd_load_hole(xas, vmf, iter, entry); |
1665 | } |
1666 | |
1667 | if (iomap->type != IOMAP_MAPPED && !(iomap->flags & IOMAP_F_SHARED)) { |
1668 | WARN_ON_ONCE(1); |
1669 | return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS; |
1670 | } |
1671 | |
1672 | err = dax_iomap_direct_access(iomap, pos, size, kaddr: &kaddr, pfnp: &pfn); |
1673 | if (err) |
1674 | return pmd ? VM_FAULT_FALLBACK : dax_fault_return(error: err); |
1675 | |
1676 | *entry = dax_insert_entry(xas, vmf, iter, entry: *entry, pfn, flags: entry_flags); |
1677 | |
1678 | if (write && iomap->flags & IOMAP_F_SHARED) { |
1679 | err = dax_iomap_copy_around(pos, length: size, align_size: size, srcmap, daddr: kaddr); |
1680 | if (err) |
1681 | return dax_fault_return(error: err); |
1682 | } |
1683 | |
1684 | if (dax_fault_is_synchronous(iter, vma: vmf->vma)) |
1685 | return dax_fault_synchronous_pfnp(pfnp, pfn); |
1686 | |
1687 | /* insert PMD pfn */ |
1688 | if (pmd) |
1689 | return vmf_insert_pfn_pmd(vmf, pfn, write); |
1690 | |
1691 | /* insert PTE pfn */ |
1692 | if (write) |
1693 | return vmf_insert_mixed_mkwrite(vma: vmf->vma, addr: vmf->address, pfn); |
1694 | return vmf_insert_mixed(vma: vmf->vma, addr: vmf->address, pfn); |
1695 | } |
1696 | |
1697 | static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, |
1698 | int *iomap_errp, const struct iomap_ops *ops) |
1699 | { |
1700 | struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
1701 | XA_STATE(xas, &mapping->i_pages, vmf->pgoff); |
1702 | struct iomap_iter iter = { |
1703 | .inode = mapping->host, |
1704 | .pos = (loff_t)vmf->pgoff << PAGE_SHIFT, |
1705 | .len = PAGE_SIZE, |
1706 | .flags = IOMAP_DAX | IOMAP_FAULT, |
1707 | }; |
1708 | vm_fault_t ret = 0; |
1709 | void *entry; |
1710 | int error; |
1711 | |
1712 | trace_dax_pte_fault(inode: iter.inode, vmf, result: ret); |
1713 | /* |
1714 | * Check whether offset isn't beyond end of file now. Caller is supposed |
1715 | * to hold locks serializing us with truncate / punch hole so this is |
1716 | * a reliable test. |
1717 | */ |
1718 | if (iter.pos >= i_size_read(inode: iter.inode)) { |
1719 | ret = VM_FAULT_SIGBUS; |
1720 | goto out; |
1721 | } |
1722 | |
1723 | if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) |
1724 | iter.flags |= IOMAP_WRITE; |
1725 | |
1726 | entry = grab_mapping_entry(xas: &xas, mapping, order: 0); |
1727 | if (xa_is_internal(entry)) { |
1728 | ret = xa_to_internal(entry); |
1729 | goto out; |
1730 | } |
1731 | |
1732 | /* |
1733 | * It is possible, particularly with mixed reads & writes to private |
1734 | * mappings, that we have raced with a PMD fault that overlaps with |
1735 | * the PTE we need to set up. If so just return and the fault will be |
1736 | * retried. |
1737 | */ |
1738 | if (pmd_trans_huge(pmd: *vmf->pmd) || pmd_devmap(pmd: *vmf->pmd)) { |
1739 | ret = VM_FAULT_NOPAGE; |
1740 | goto unlock_entry; |
1741 | } |
1742 | |
1743 | while ((error = iomap_iter(iter: &iter, ops)) > 0) { |
1744 | if (WARN_ON_ONCE(iomap_length(&iter) < PAGE_SIZE)) { |
1745 | iter.processed = -EIO; /* fs corruption? */ |
1746 | continue; |
1747 | } |
1748 | |
1749 | ret = dax_fault_iter(vmf, iter: &iter, pfnp, xas: &xas, entry: &entry, pmd: false); |
1750 | if (ret != VM_FAULT_SIGBUS && |
1751 | (iter.iomap.flags & IOMAP_F_NEW)) { |
1752 | count_vm_event(item: PGMAJFAULT); |
1753 | count_memcg_event_mm(mm: vmf->vma->vm_mm, idx: PGMAJFAULT); |
1754 | ret |= VM_FAULT_MAJOR; |
1755 | } |
1756 | |
1757 | if (!(ret & VM_FAULT_ERROR)) |
1758 | iter.processed = PAGE_SIZE; |
1759 | } |
1760 | |
1761 | if (iomap_errp) |
1762 | *iomap_errp = error; |
1763 | if (!ret && error) |
1764 | ret = dax_fault_return(error); |
1765 | |
1766 | unlock_entry: |
1767 | dax_unlock_entry(xas: &xas, entry); |
1768 | out: |
1769 | trace_dax_pte_fault_done(inode: iter.inode, vmf, result: ret); |
1770 | return ret; |
1771 | } |
1772 | |
1773 | #ifdef CONFIG_FS_DAX_PMD |
1774 | static bool dax_fault_check_fallback(struct vm_fault *vmf, struct xa_state *xas, |
1775 | pgoff_t max_pgoff) |
1776 | { |
1777 | unsigned long pmd_addr = vmf->address & PMD_MASK; |
1778 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
1779 | |
1780 | /* |
1781 | * Make sure that the faulting address's PMD offset (color) matches |
1782 | * the PMD offset from the start of the file. This is necessary so |
1783 | * that a PMD range in the page table overlaps exactly with a PMD |
1784 | * range in the page cache. |
1785 | */ |
1786 | if ((vmf->pgoff & PG_PMD_COLOUR) != |
1787 | ((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR)) |
1788 | return true; |
1789 | |
1790 | /* Fall back to PTEs if we're going to COW */ |
1791 | if (write && !(vmf->vma->vm_flags & VM_SHARED)) |
1792 | return true; |
1793 | |
1794 | /* If the PMD would extend outside the VMA */ |
1795 | if (pmd_addr < vmf->vma->vm_start) |
1796 | return true; |
1797 | if ((pmd_addr + PMD_SIZE) > vmf->vma->vm_end) |
1798 | return true; |
1799 | |
1800 | /* If the PMD would extend beyond the file size */ |
1801 | if ((xas->xa_index | PG_PMD_COLOUR) >= max_pgoff) |
1802 | return true; |
1803 | |
1804 | return false; |
1805 | } |
1806 | |
1807 | static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, |
1808 | const struct iomap_ops *ops) |
1809 | { |
1810 | struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
1811 | XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER); |
1812 | struct iomap_iter iter = { |
1813 | .inode = mapping->host, |
1814 | .len = PMD_SIZE, |
1815 | .flags = IOMAP_DAX | IOMAP_FAULT, |
1816 | }; |
1817 | vm_fault_t ret = VM_FAULT_FALLBACK; |
1818 | pgoff_t max_pgoff; |
1819 | void *entry; |
1820 | |
1821 | if (vmf->flags & FAULT_FLAG_WRITE) |
1822 | iter.flags |= IOMAP_WRITE; |
1823 | |
1824 | /* |
1825 | * Check whether offset isn't beyond end of file now. Caller is |
1826 | * supposed to hold locks serializing us with truncate / punch hole so |
1827 | * this is a reliable test. |
1828 | */ |
1829 | max_pgoff = DIV_ROUND_UP(i_size_read(iter.inode), PAGE_SIZE); |
1830 | |
1831 | trace_dax_pmd_fault(inode: iter.inode, vmf, max_pgoff, result: 0); |
1832 | |
1833 | if (xas.xa_index >= max_pgoff) { |
1834 | ret = VM_FAULT_SIGBUS; |
1835 | goto out; |
1836 | } |
1837 | |
1838 | if (dax_fault_check_fallback(vmf, xas: &xas, max_pgoff)) |
1839 | goto fallback; |
1840 | |
1841 | /* |
1842 | * grab_mapping_entry() will make sure we get an empty PMD entry, |
1843 | * a zero PMD entry or a DAX PMD. If it can't (because a PTE |
1844 | * entry is already in the array, for instance), it will return |
1845 | * VM_FAULT_FALLBACK. |
1846 | */ |
1847 | entry = grab_mapping_entry(xas: &xas, mapping, PMD_ORDER); |
1848 | if (xa_is_internal(entry)) { |
1849 | ret = xa_to_internal(entry); |
1850 | goto fallback; |
1851 | } |
1852 | |
1853 | /* |
1854 | * It is possible, particularly with mixed reads & writes to private |
1855 | * mappings, that we have raced with a PTE fault that overlaps with |
1856 | * the PMD we need to set up. If so just return and the fault will be |
1857 | * retried. |
1858 | */ |
1859 | if (!pmd_none(pmd: *vmf->pmd) && !pmd_trans_huge(pmd: *vmf->pmd) && |
1860 | !pmd_devmap(pmd: *vmf->pmd)) { |
1861 | ret = 0; |
1862 | goto unlock_entry; |
1863 | } |
1864 | |
1865 | iter.pos = (loff_t)xas.xa_index << PAGE_SHIFT; |
1866 | while (iomap_iter(iter: &iter, ops) > 0) { |
1867 | if (iomap_length(iter: &iter) < PMD_SIZE) |
1868 | continue; /* actually breaks out of the loop */ |
1869 | |
1870 | ret = dax_fault_iter(vmf, iter: &iter, pfnp, xas: &xas, entry: &entry, pmd: true); |
1871 | if (ret != VM_FAULT_FALLBACK) |
1872 | iter.processed = PMD_SIZE; |
1873 | } |
1874 | |
1875 | unlock_entry: |
1876 | dax_unlock_entry(xas: &xas, entry); |
1877 | fallback: |
1878 | if (ret == VM_FAULT_FALLBACK) { |
1879 | split_huge_pmd(vmf->vma, vmf->pmd, vmf->address); |
1880 | count_vm_event(item: THP_FAULT_FALLBACK); |
1881 | } |
1882 | out: |
1883 | trace_dax_pmd_fault_done(inode: iter.inode, vmf, max_pgoff, result: ret); |
1884 | return ret; |
1885 | } |
1886 | #else |
1887 | static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, |
1888 | const struct iomap_ops *ops) |
1889 | { |
1890 | return VM_FAULT_FALLBACK; |
1891 | } |
1892 | #endif /* CONFIG_FS_DAX_PMD */ |
1893 | |
1894 | /** |
1895 | * dax_iomap_fault - handle a page fault on a DAX file |
1896 | * @vmf: The description of the fault |
1897 | * @order: Order of the page to fault in |
1898 | * @pfnp: PFN to insert for synchronous faults if fsync is required |
1899 | * @iomap_errp: Storage for detailed error code in case of error |
1900 | * @ops: Iomap ops passed from the file system |
1901 | * |
1902 | * When a page fault occurs, filesystems may call this helper in |
1903 | * their fault handler for DAX files. dax_iomap_fault() assumes the caller |
1904 | * has done all the necessary locking for page fault to proceed |
1905 | * successfully. |
1906 | */ |
1907 | vm_fault_t dax_iomap_fault(struct vm_fault *vmf, unsigned int order, |
1908 | pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops) |
1909 | { |
1910 | if (order == 0) |
1911 | return dax_iomap_pte_fault(vmf, pfnp, iomap_errp, ops); |
1912 | else if (order == PMD_ORDER) |
1913 | return dax_iomap_pmd_fault(vmf, pfnp, ops); |
1914 | else |
1915 | return VM_FAULT_FALLBACK; |
1916 | } |
1917 | EXPORT_SYMBOL_GPL(dax_iomap_fault); |
1918 | |
1919 | /* |
1920 | * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables |
1921 | * @vmf: The description of the fault |
1922 | * @pfn: PFN to insert |
1923 | * @order: Order of entry to insert. |
1924 | * |
1925 | * This function inserts a writeable PTE or PMD entry into the page tables |
1926 | * for an mmaped DAX file. It also marks the page cache entry as dirty. |
1927 | */ |
1928 | static vm_fault_t |
1929 | dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order) |
1930 | { |
1931 | struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
1932 | XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, order); |
1933 | void *entry; |
1934 | vm_fault_t ret; |
1935 | |
1936 | xas_lock_irq(&xas); |
1937 | entry = get_unlocked_entry(xas: &xas, order); |
1938 | /* Did we race with someone splitting entry or so? */ |
1939 | if (!entry || dax_is_conflict(entry) || |
1940 | (order == 0 && !dax_is_pte_entry(entry))) { |
1941 | put_unlocked_entry(xas: &xas, entry, mode: WAKE_NEXT); |
1942 | xas_unlock_irq(&xas); |
1943 | trace_dax_insert_pfn_mkwrite_no_entry(inode: mapping->host, vmf, |
1944 | result: VM_FAULT_NOPAGE); |
1945 | return VM_FAULT_NOPAGE; |
1946 | } |
1947 | xas_set_mark(&xas, PAGECACHE_TAG_DIRTY); |
1948 | dax_lock_entry(xas: &xas, entry); |
1949 | xas_unlock_irq(&xas); |
1950 | if (order == 0) |
1951 | ret = vmf_insert_mixed_mkwrite(vma: vmf->vma, addr: vmf->address, pfn); |
1952 | #ifdef CONFIG_FS_DAX_PMD |
1953 | else if (order == PMD_ORDER) |
1954 | ret = vmf_insert_pfn_pmd(vmf, pfn, write: FAULT_FLAG_WRITE); |
1955 | #endif |
1956 | else |
1957 | ret = VM_FAULT_FALLBACK; |
1958 | dax_unlock_entry(xas: &xas, entry); |
1959 | trace_dax_insert_pfn_mkwrite(inode: mapping->host, vmf, result: ret); |
1960 | return ret; |
1961 | } |
1962 | |
1963 | /** |
1964 | * dax_finish_sync_fault - finish synchronous page fault |
1965 | * @vmf: The description of the fault |
1966 | * @order: Order of entry to be inserted |
1967 | * @pfn: PFN to insert |
1968 | * |
1969 | * This function ensures that the file range touched by the page fault is |
1970 | * stored persistently on the media and handles inserting of appropriate page |
1971 | * table entry. |
1972 | */ |
1973 | vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf, unsigned int order, |
1974 | pfn_t pfn) |
1975 | { |
1976 | int err; |
1977 | loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT; |
1978 | size_t len = PAGE_SIZE << order; |
1979 | |
1980 | err = vfs_fsync_range(file: vmf->vma->vm_file, start, end: start + len - 1, datasync: 1); |
1981 | if (err) |
1982 | return VM_FAULT_SIGBUS; |
1983 | return dax_insert_pfn_mkwrite(vmf, pfn, order); |
1984 | } |
1985 | EXPORT_SYMBOL_GPL(dax_finish_sync_fault); |
1986 | |
1987 | static loff_t dax_range_compare_iter(struct iomap_iter *it_src, |
1988 | struct iomap_iter *it_dest, u64 len, bool *same) |
1989 | { |
1990 | const struct iomap *smap = &it_src->iomap; |
1991 | const struct iomap *dmap = &it_dest->iomap; |
1992 | loff_t pos1 = it_src->pos, pos2 = it_dest->pos; |
1993 | void *saddr, *daddr; |
1994 | int id, ret; |
1995 | |
1996 | len = min(len, min(smap->length, dmap->length)); |
1997 | |
1998 | if (smap->type == IOMAP_HOLE && dmap->type == IOMAP_HOLE) { |
1999 | *same = true; |
2000 | return len; |
2001 | } |
2002 | |
2003 | if (smap->type == IOMAP_HOLE || dmap->type == IOMAP_HOLE) { |
2004 | *same = false; |
2005 | return 0; |
2006 | } |
2007 | |
2008 | id = dax_read_lock(); |
2009 | ret = dax_iomap_direct_access(iomap: smap, pos: pos1, ALIGN(pos1 + len, PAGE_SIZE), |
2010 | kaddr: &saddr, NULL); |
2011 | if (ret < 0) |
2012 | goto out_unlock; |
2013 | |
2014 | ret = dax_iomap_direct_access(iomap: dmap, pos: pos2, ALIGN(pos2 + len, PAGE_SIZE), |
2015 | kaddr: &daddr, NULL); |
2016 | if (ret < 0) |
2017 | goto out_unlock; |
2018 | |
2019 | *same = !memcmp(p: saddr, q: daddr, size: len); |
2020 | if (!*same) |
2021 | len = 0; |
2022 | dax_read_unlock(id); |
2023 | return len; |
2024 | |
2025 | out_unlock: |
2026 | dax_read_unlock(id); |
2027 | return -EIO; |
2028 | } |
2029 | |
2030 | int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff, |
2031 | struct inode *dst, loff_t dstoff, loff_t len, bool *same, |
2032 | const struct iomap_ops *ops) |
2033 | { |
2034 | struct iomap_iter src_iter = { |
2035 | .inode = src, |
2036 | .pos = srcoff, |
2037 | .len = len, |
2038 | .flags = IOMAP_DAX, |
2039 | }; |
2040 | struct iomap_iter dst_iter = { |
2041 | .inode = dst, |
2042 | .pos = dstoff, |
2043 | .len = len, |
2044 | .flags = IOMAP_DAX, |
2045 | }; |
2046 | int ret, compared = 0; |
2047 | |
2048 | while ((ret = iomap_iter(iter: &src_iter, ops)) > 0 && |
2049 | (ret = iomap_iter(iter: &dst_iter, ops)) > 0) { |
2050 | compared = dax_range_compare_iter(it_src: &src_iter, it_dest: &dst_iter, |
2051 | min(src_iter.len, dst_iter.len), same); |
2052 | if (compared < 0) |
2053 | return ret; |
2054 | src_iter.processed = dst_iter.processed = compared; |
2055 | } |
2056 | return ret; |
2057 | } |
2058 | |
2059 | int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in, |
2060 | struct file *file_out, loff_t pos_out, |
2061 | loff_t *len, unsigned int remap_flags, |
2062 | const struct iomap_ops *ops) |
2063 | { |
2064 | return __generic_remap_file_range_prep(file_in, pos_in, file_out, |
2065 | pos_out, len, remap_flags, dax_read_ops: ops); |
2066 | } |
2067 | EXPORT_SYMBOL_GPL(dax_remap_file_range_prep); |
2068 | |