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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> | |
20 | #include <linux/dax.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/genhd.h> | |
23 | #include <linux/highmem.h> | |
24 | #include <linux/memcontrol.h> | |
25 | #include <linux/mm.h> | |
26 | #include <linux/mutex.h> | |
27 | #include <linux/pagevec.h> | |
28 | #include <linux/pmem.h> | |
29 | #include <linux/sched.h> | |
30 | #include <linux/uio.h> | |
31 | #include <linux/vmstat.h> | |
32 | #include <linux/pfn_t.h> | |
33 | #include <linux/sizes.h> | |
34 | #include <linux/mmu_notifier.h> | |
35 | #include <linux/iomap.h> | |
36 | #include "internal.h" | |
37 | ||
38 | /* We choose 4096 entries - same as per-zone page wait tables */ | |
39 | #define DAX_WAIT_TABLE_BITS 12 | |
40 | #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS) | |
41 | ||
42 | static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; | |
43 | ||
44 | static int __init init_dax_wait_table(void) | |
45 | { | |
46 | int i; | |
47 | ||
48 | for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++) | |
49 | init_waitqueue_head(wait_table + i); | |
50 | return 0; | |
51 | } | |
52 | fs_initcall(init_dax_wait_table); | |
53 | ||
54 | static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax) | |
55 | { | |
56 | struct request_queue *q = bdev->bd_queue; | |
57 | long rc = -EIO; | |
58 | ||
59 | dax->addr = ERR_PTR(-EIO); | |
60 | if (blk_queue_enter(q, true) != 0) | |
61 | return rc; | |
62 | ||
63 | rc = bdev_direct_access(bdev, dax); | |
64 | if (rc < 0) { | |
65 | dax->addr = ERR_PTR(rc); | |
66 | blk_queue_exit(q); | |
67 | return rc; | |
68 | } | |
69 | return rc; | |
70 | } | |
71 | ||
72 | static void dax_unmap_atomic(struct block_device *bdev, | |
73 | const struct blk_dax_ctl *dax) | |
74 | { | |
75 | if (IS_ERR(dax->addr)) | |
76 | return; | |
77 | blk_queue_exit(bdev->bd_queue); | |
78 | } | |
79 | ||
80 | static int dax_is_pmd_entry(void *entry) | |
81 | { | |
82 | return (unsigned long)entry & RADIX_DAX_PMD; | |
83 | } | |
84 | ||
85 | static int dax_is_pte_entry(void *entry) | |
86 | { | |
87 | return !((unsigned long)entry & RADIX_DAX_PMD); | |
88 | } | |
89 | ||
90 | static int dax_is_zero_entry(void *entry) | |
91 | { | |
92 | return (unsigned long)entry & RADIX_DAX_HZP; | |
93 | } | |
94 | ||
95 | static int dax_is_empty_entry(void *entry) | |
96 | { | |
97 | return (unsigned long)entry & RADIX_DAX_EMPTY; | |
98 | } | |
99 | ||
100 | struct page *read_dax_sector(struct block_device *bdev, sector_t n) | |
101 | { | |
102 | struct page *page = alloc_pages(GFP_KERNEL, 0); | |
103 | struct blk_dax_ctl dax = { | |
104 | .size = PAGE_SIZE, | |
105 | .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), | |
106 | }; | |
107 | long rc; | |
108 | ||
109 | if (!page) | |
110 | return ERR_PTR(-ENOMEM); | |
111 | ||
112 | rc = dax_map_atomic(bdev, &dax); | |
113 | if (rc < 0) | |
114 | return ERR_PTR(rc); | |
115 | memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE); | |
116 | dax_unmap_atomic(bdev, &dax); | |
117 | return page; | |
118 | } | |
119 | ||
120 | /* | |
121 | * DAX radix tree locking | |
122 | */ | |
123 | struct exceptional_entry_key { | |
124 | struct address_space *mapping; | |
125 | pgoff_t entry_start; | |
126 | }; | |
127 | ||
128 | struct wait_exceptional_entry_queue { | |
129 | wait_queue_t wait; | |
130 | struct exceptional_entry_key key; | |
131 | }; | |
132 | ||
133 | static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping, | |
134 | pgoff_t index, void *entry, struct exceptional_entry_key *key) | |
135 | { | |
136 | unsigned long hash; | |
137 | ||
138 | /* | |
139 | * If 'entry' is a PMD, align the 'index' that we use for the wait | |
140 | * queue to the start of that PMD. This ensures that all offsets in | |
141 | * the range covered by the PMD map to the same bit lock. | |
142 | */ | |
143 | if (dax_is_pmd_entry(entry)) | |
144 | index &= ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1); | |
145 | ||
146 | key->mapping = mapping; | |
147 | key->entry_start = index; | |
148 | ||
149 | hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS); | |
150 | return wait_table + hash; | |
151 | } | |
152 | ||
153 | static int wake_exceptional_entry_func(wait_queue_t *wait, unsigned int mode, | |
154 | int sync, void *keyp) | |
155 | { | |
156 | struct exceptional_entry_key *key = keyp; | |
157 | struct wait_exceptional_entry_queue *ewait = | |
158 | container_of(wait, struct wait_exceptional_entry_queue, wait); | |
159 | ||
160 | if (key->mapping != ewait->key.mapping || | |
161 | key->entry_start != ewait->key.entry_start) | |
162 | return 0; | |
163 | return autoremove_wake_function(wait, mode, sync, NULL); | |
164 | } | |
165 | ||
166 | /* | |
167 | * Check whether the given slot is locked. The function must be called with | |
168 | * mapping->tree_lock held | |
169 | */ | |
170 | static inline int slot_locked(struct address_space *mapping, void **slot) | |
171 | { | |
172 | unsigned long entry = (unsigned long) | |
173 | radix_tree_deref_slot_protected(slot, &mapping->tree_lock); | |
174 | return entry & RADIX_DAX_ENTRY_LOCK; | |
175 | } | |
176 | ||
177 | /* | |
178 | * Mark the given slot is locked. The function must be called with | |
179 | * mapping->tree_lock held | |
180 | */ | |
181 | static inline void *lock_slot(struct address_space *mapping, void **slot) | |
182 | { | |
183 | unsigned long entry = (unsigned long) | |
184 | radix_tree_deref_slot_protected(slot, &mapping->tree_lock); | |
185 | ||
186 | entry |= RADIX_DAX_ENTRY_LOCK; | |
187 | radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); | |
188 | return (void *)entry; | |
189 | } | |
190 | ||
191 | /* | |
192 | * Mark the given slot is unlocked. The function must be called with | |
193 | * mapping->tree_lock held | |
194 | */ | |
195 | static inline void *unlock_slot(struct address_space *mapping, void **slot) | |
196 | { | |
197 | unsigned long entry = (unsigned long) | |
198 | radix_tree_deref_slot_protected(slot, &mapping->tree_lock); | |
199 | ||
200 | entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK; | |
201 | radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); | |
202 | return (void *)entry; | |
203 | } | |
204 | ||
205 | /* | |
206 | * Lookup entry in radix tree, wait for it to become unlocked if it is | |
207 | * exceptional entry and return it. The caller must call | |
208 | * put_unlocked_mapping_entry() when he decided not to lock the entry or | |
209 | * put_locked_mapping_entry() when he locked the entry and now wants to | |
210 | * unlock it. | |
211 | * | |
212 | * The function must be called with mapping->tree_lock held. | |
213 | */ | |
214 | static void *get_unlocked_mapping_entry(struct address_space *mapping, | |
215 | pgoff_t index, void ***slotp) | |
216 | { | |
217 | void *entry, **slot; | |
218 | struct wait_exceptional_entry_queue ewait; | |
219 | wait_queue_head_t *wq; | |
220 | ||
221 | init_wait(&ewait.wait); | |
222 | ewait.wait.func = wake_exceptional_entry_func; | |
223 | ||
224 | for (;;) { | |
225 | entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, | |
226 | &slot); | |
227 | if (!entry || !radix_tree_exceptional_entry(entry) || | |
228 | !slot_locked(mapping, slot)) { | |
229 | if (slotp) | |
230 | *slotp = slot; | |
231 | return entry; | |
232 | } | |
233 | ||
234 | wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key); | |
235 | prepare_to_wait_exclusive(wq, &ewait.wait, | |
236 | TASK_UNINTERRUPTIBLE); | |
237 | spin_unlock_irq(&mapping->tree_lock); | |
238 | schedule(); | |
239 | finish_wait(wq, &ewait.wait); | |
240 | spin_lock_irq(&mapping->tree_lock); | |
241 | } | |
242 | } | |
243 | ||
244 | static void dax_unlock_mapping_entry(struct address_space *mapping, | |
245 | pgoff_t index) | |
246 | { | |
247 | void *entry, **slot; | |
248 | ||
249 | spin_lock_irq(&mapping->tree_lock); | |
250 | entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot); | |
251 | if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) || | |
252 | !slot_locked(mapping, slot))) { | |
253 | spin_unlock_irq(&mapping->tree_lock); | |
254 | return; | |
255 | } | |
256 | unlock_slot(mapping, slot); | |
257 | spin_unlock_irq(&mapping->tree_lock); | |
258 | dax_wake_mapping_entry_waiter(mapping, index, entry, false); | |
259 | } | |
260 | ||
261 | static void put_locked_mapping_entry(struct address_space *mapping, | |
262 | pgoff_t index, void *entry) | |
263 | { | |
264 | if (!radix_tree_exceptional_entry(entry)) { | |
265 | unlock_page(entry); | |
266 | put_page(entry); | |
267 | } else { | |
268 | dax_unlock_mapping_entry(mapping, index); | |
269 | } | |
270 | } | |
271 | ||
272 | /* | |
273 | * Called when we are done with radix tree entry we looked up via | |
274 | * get_unlocked_mapping_entry() and which we didn't lock in the end. | |
275 | */ | |
276 | static void put_unlocked_mapping_entry(struct address_space *mapping, | |
277 | pgoff_t index, void *entry) | |
278 | { | |
279 | if (!radix_tree_exceptional_entry(entry)) | |
280 | return; | |
281 | ||
282 | /* We have to wake up next waiter for the radix tree entry lock */ | |
283 | dax_wake_mapping_entry_waiter(mapping, index, entry, false); | |
284 | } | |
285 | ||
286 | /* | |
287 | * Find radix tree entry at given index. If it points to a page, return with | |
288 | * the page locked. If it points to the exceptional entry, return with the | |
289 | * radix tree entry locked. If the radix tree doesn't contain given index, | |
290 | * create empty exceptional entry for the index and return with it locked. | |
291 | * | |
292 | * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will | |
293 | * either return that locked entry or will return an error. This error will | |
294 | * happen if there are any 4k entries (either zero pages or DAX entries) | |
295 | * within the 2MiB range that we are requesting. | |
296 | * | |
297 | * We always favor 4k entries over 2MiB entries. There isn't a flow where we | |
298 | * evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB | |
299 | * insertion will fail if it finds any 4k entries already in the tree, and a | |
300 | * 4k insertion will cause an existing 2MiB entry to be unmapped and | |
301 | * downgraded to 4k entries. This happens for both 2MiB huge zero pages as | |
302 | * well as 2MiB empty entries. | |
303 | * | |
304 | * The exception to this downgrade path is for 2MiB DAX PMD entries that have | |
305 | * real storage backing them. We will leave these real 2MiB DAX entries in | |
306 | * the tree, and PTE writes will simply dirty the entire 2MiB DAX entry. | |
307 | * | |
308 | * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For | |
309 | * persistent memory the benefit is doubtful. We can add that later if we can | |
310 | * show it helps. | |
311 | */ | |
312 | static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, | |
313 | unsigned long size_flag) | |
314 | { | |
315 | bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */ | |
316 | void *entry, **slot; | |
317 | ||
318 | restart: | |
319 | spin_lock_irq(&mapping->tree_lock); | |
320 | entry = get_unlocked_mapping_entry(mapping, index, &slot); | |
321 | ||
322 | if (entry) { | |
323 | if (size_flag & RADIX_DAX_PMD) { | |
324 | if (!radix_tree_exceptional_entry(entry) || | |
325 | dax_is_pte_entry(entry)) { | |
326 | put_unlocked_mapping_entry(mapping, index, | |
327 | entry); | |
328 | entry = ERR_PTR(-EEXIST); | |
329 | goto out_unlock; | |
330 | } | |
331 | } else { /* trying to grab a PTE entry */ | |
332 | if (radix_tree_exceptional_entry(entry) && | |
333 | dax_is_pmd_entry(entry) && | |
334 | (dax_is_zero_entry(entry) || | |
335 | dax_is_empty_entry(entry))) { | |
336 | pmd_downgrade = true; | |
337 | } | |
338 | } | |
339 | } | |
340 | ||
341 | /* No entry for given index? Make sure radix tree is big enough. */ | |
342 | if (!entry || pmd_downgrade) { | |
343 | int err; | |
344 | ||
345 | if (pmd_downgrade) { | |
346 | /* | |
347 | * Make sure 'entry' remains valid while we drop | |
348 | * mapping->tree_lock. | |
349 | */ | |
350 | entry = lock_slot(mapping, slot); | |
351 | } | |
352 | ||
353 | spin_unlock_irq(&mapping->tree_lock); | |
354 | /* | |
355 | * Besides huge zero pages the only other thing that gets | |
356 | * downgraded are empty entries which don't need to be | |
357 | * unmapped. | |
358 | */ | |
359 | if (pmd_downgrade && dax_is_zero_entry(entry)) | |
360 | unmap_mapping_range(mapping, | |
361 | (index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); | |
362 | ||
363 | err = radix_tree_preload( | |
364 | mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM); | |
365 | if (err) { | |
366 | if (pmd_downgrade) | |
367 | put_locked_mapping_entry(mapping, index, entry); | |
368 | return ERR_PTR(err); | |
369 | } | |
370 | spin_lock_irq(&mapping->tree_lock); | |
371 | ||
372 | if (pmd_downgrade) { | |
373 | radix_tree_delete(&mapping->page_tree, index); | |
374 | mapping->nrexceptional--; | |
375 | dax_wake_mapping_entry_waiter(mapping, index, entry, | |
376 | true); | |
377 | } | |
378 | ||
379 | entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY); | |
380 | ||
381 | err = __radix_tree_insert(&mapping->page_tree, index, | |
382 | dax_radix_order(entry), entry); | |
383 | radix_tree_preload_end(); | |
384 | if (err) { | |
385 | spin_unlock_irq(&mapping->tree_lock); | |
386 | /* | |
387 | * Someone already created the entry? This is a | |
388 | * normal failure when inserting PMDs in a range | |
389 | * that already contains PTEs. In that case we want | |
390 | * to return -EEXIST immediately. | |
391 | */ | |
392 | if (err == -EEXIST && !(size_flag & RADIX_DAX_PMD)) | |
393 | goto restart; | |
394 | /* | |
395 | * Our insertion of a DAX PMD entry failed, most | |
396 | * likely because it collided with a PTE sized entry | |
397 | * at a different index in the PMD range. We haven't | |
398 | * inserted anything into the radix tree and have no | |
399 | * waiters to wake. | |
400 | */ | |
401 | return ERR_PTR(err); | |
402 | } | |
403 | /* Good, we have inserted empty locked entry into the tree. */ | |
404 | mapping->nrexceptional++; | |
405 | spin_unlock_irq(&mapping->tree_lock); | |
406 | return entry; | |
407 | } | |
408 | /* Normal page in radix tree? */ | |
409 | if (!radix_tree_exceptional_entry(entry)) { | |
410 | struct page *page = entry; | |
411 | ||
412 | get_page(page); | |
413 | spin_unlock_irq(&mapping->tree_lock); | |
414 | lock_page(page); | |
415 | /* Page got truncated? Retry... */ | |
416 | if (unlikely(page->mapping != mapping)) { | |
417 | unlock_page(page); | |
418 | put_page(page); | |
419 | goto restart; | |
420 | } | |
421 | return page; | |
422 | } | |
423 | entry = lock_slot(mapping, slot); | |
424 | out_unlock: | |
425 | spin_unlock_irq(&mapping->tree_lock); | |
426 | return entry; | |
427 | } | |
428 | ||
429 | /* | |
430 | * We do not necessarily hold the mapping->tree_lock when we call this | |
431 | * function so it is possible that 'entry' is no longer a valid item in the | |
432 | * radix tree. This is okay because all we really need to do is to find the | |
433 | * correct waitqueue where tasks might be waiting for that old 'entry' and | |
434 | * wake them. | |
435 | */ | |
436 | void dax_wake_mapping_entry_waiter(struct address_space *mapping, | |
437 | pgoff_t index, void *entry, bool wake_all) | |
438 | { | |
439 | struct exceptional_entry_key key; | |
440 | wait_queue_head_t *wq; | |
441 | ||
442 | wq = dax_entry_waitqueue(mapping, index, entry, &key); | |
443 | ||
444 | /* | |
445 | * Checking for locked entry and prepare_to_wait_exclusive() happens | |
446 | * under mapping->tree_lock, ditto for entry handling in our callers. | |
447 | * So at this point all tasks that could have seen our entry locked | |
448 | * must be in the waitqueue and the following check will see them. | |
449 | */ | |
450 | if (waitqueue_active(wq)) | |
451 | __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key); | |
452 | } | |
453 | ||
454 | static int __dax_invalidate_mapping_entry(struct address_space *mapping, | |
455 | pgoff_t index, bool trunc) | |
456 | { | |
457 | int ret = 0; | |
458 | void *entry; | |
459 | struct radix_tree_root *page_tree = &mapping->page_tree; | |
460 | ||
461 | spin_lock_irq(&mapping->tree_lock); | |
462 | entry = get_unlocked_mapping_entry(mapping, index, NULL); | |
463 | if (!entry || !radix_tree_exceptional_entry(entry)) | |
464 | goto out; | |
465 | if (!trunc && | |
466 | (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) || | |
467 | radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))) | |
468 | goto out; | |
469 | radix_tree_delete(page_tree, index); | |
470 | mapping->nrexceptional--; | |
471 | ret = 1; | |
472 | out: | |
473 | put_unlocked_mapping_entry(mapping, index, entry); | |
474 | spin_unlock_irq(&mapping->tree_lock); | |
475 | return ret; | |
476 | } | |
477 | /* | |
478 | * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree | |
479 | * entry to get unlocked before deleting it. | |
480 | */ | |
481 | int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) | |
482 | { | |
483 | int ret = __dax_invalidate_mapping_entry(mapping, index, true); | |
484 | ||
485 | /* | |
486 | * This gets called from truncate / punch_hole path. As such, the caller | |
487 | * must hold locks protecting against concurrent modifications of the | |
488 | * radix tree (usually fs-private i_mmap_sem for writing). Since the | |
489 | * caller has seen exceptional entry for this index, we better find it | |
490 | * at that index as well... | |
491 | */ | |
492 | WARN_ON_ONCE(!ret); | |
493 | return ret; | |
494 | } | |
495 | ||
496 | /* | |
497 | * Invalidate exceptional DAX entry if easily possible. This handles DAX | |
498 | * entries for invalidate_inode_pages() so we evict the entry only if we can | |
499 | * do so without blocking. | |
500 | */ | |
501 | int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index) | |
502 | { | |
503 | int ret = 0; | |
504 | void *entry, **slot; | |
505 | struct radix_tree_root *page_tree = &mapping->page_tree; | |
506 | ||
507 | spin_lock_irq(&mapping->tree_lock); | |
508 | entry = __radix_tree_lookup(page_tree, index, NULL, &slot); | |
509 | if (!entry || !radix_tree_exceptional_entry(entry) || | |
510 | slot_locked(mapping, slot)) | |
511 | goto out; | |
512 | if (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) || | |
513 | radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) | |
514 | goto out; | |
515 | radix_tree_delete(page_tree, index); | |
516 | mapping->nrexceptional--; | |
517 | ret = 1; | |
518 | out: | |
519 | spin_unlock_irq(&mapping->tree_lock); | |
520 | if (ret) | |
521 | dax_wake_mapping_entry_waiter(mapping, index, entry, true); | |
522 | return ret; | |
523 | } | |
524 | ||
525 | /* | |
526 | * Invalidate exceptional DAX entry if it is clean. | |
527 | */ | |
528 | int dax_invalidate_mapping_entry_sync(struct address_space *mapping, | |
529 | pgoff_t index) | |
530 | { | |
531 | return __dax_invalidate_mapping_entry(mapping, index, false); | |
532 | } | |
533 | ||
534 | /* | |
535 | * The user has performed a load from a hole in the file. Allocating | |
536 | * a new page in the file would cause excessive storage usage for | |
537 | * workloads with sparse files. We allocate a page cache page instead. | |
538 | * We'll kick it out of the page cache if it's ever written to, | |
539 | * otherwise it will simply fall out of the page cache under memory | |
540 | * pressure without ever having been dirtied. | |
541 | */ | |
542 | static int dax_load_hole(struct address_space *mapping, void **entry, | |
543 | struct vm_fault *vmf) | |
544 | { | |
545 | struct page *page; | |
546 | int ret; | |
547 | ||
548 | /* Hole page already exists? Return it... */ | |
549 | if (!radix_tree_exceptional_entry(*entry)) { | |
550 | page = *entry; | |
551 | goto out; | |
552 | } | |
553 | ||
554 | /* This will replace locked radix tree entry with a hole page */ | |
555 | page = find_or_create_page(mapping, vmf->pgoff, | |
556 | vmf->gfp_mask | __GFP_ZERO); | |
557 | if (!page) | |
558 | return VM_FAULT_OOM; | |
559 | out: | |
560 | vmf->page = page; | |
561 | ret = finish_fault(vmf); | |
562 | vmf->page = NULL; | |
563 | *entry = page; | |
564 | if (!ret) { | |
565 | /* Grab reference for PTE that is now referencing the page */ | |
566 | get_page(page); | |
567 | return VM_FAULT_NOPAGE; | |
568 | } | |
569 | return ret; | |
570 | } | |
571 | ||
572 | static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size, | |
573 | struct page *to, unsigned long vaddr) | |
574 | { | |
575 | struct blk_dax_ctl dax = { | |
576 | .sector = sector, | |
577 | .size = size, | |
578 | }; | |
579 | void *vto; | |
580 | ||
581 | if (dax_map_atomic(bdev, &dax) < 0) | |
582 | return PTR_ERR(dax.addr); | |
583 | vto = kmap_atomic(to); | |
584 | copy_user_page(vto, (void __force *)dax.addr, vaddr, to); | |
585 | kunmap_atomic(vto); | |
586 | dax_unmap_atomic(bdev, &dax); | |
587 | return 0; | |
588 | } | |
589 | ||
590 | /* | |
591 | * By this point grab_mapping_entry() has ensured that we have a locked entry | |
592 | * of the appropriate size so we don't have to worry about downgrading PMDs to | |
593 | * PTEs. If we happen to be trying to insert a PTE and there is a PMD | |
594 | * already in the tree, we will skip the insertion and just dirty the PMD as | |
595 | * appropriate. | |
596 | */ | |
597 | static void *dax_insert_mapping_entry(struct address_space *mapping, | |
598 | struct vm_fault *vmf, | |
599 | void *entry, sector_t sector, | |
600 | unsigned long flags) | |
601 | { | |
602 | struct radix_tree_root *page_tree = &mapping->page_tree; | |
603 | int error = 0; | |
604 | bool hole_fill = false; | |
605 | void *new_entry; | |
606 | pgoff_t index = vmf->pgoff; | |
607 | ||
608 | if (vmf->flags & FAULT_FLAG_WRITE) | |
609 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
610 | ||
611 | /* Replacing hole page with block mapping? */ | |
612 | if (!radix_tree_exceptional_entry(entry)) { | |
613 | hole_fill = true; | |
614 | /* | |
615 | * Unmap the page now before we remove it from page cache below. | |
616 | * The page is locked so it cannot be faulted in again. | |
617 | */ | |
618 | unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, | |
619 | PAGE_SIZE, 0); | |
620 | error = radix_tree_preload(vmf->gfp_mask & ~__GFP_HIGHMEM); | |
621 | if (error) | |
622 | return ERR_PTR(error); | |
623 | } else if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_HZP)) { | |
624 | /* replacing huge zero page with PMD block mapping */ | |
625 | unmap_mapping_range(mapping, | |
626 | (vmf->pgoff << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); | |
627 | } | |
628 | ||
629 | spin_lock_irq(&mapping->tree_lock); | |
630 | new_entry = dax_radix_locked_entry(sector, flags); | |
631 | ||
632 | if (hole_fill) { | |
633 | __delete_from_page_cache(entry, NULL); | |
634 | /* Drop pagecache reference */ | |
635 | put_page(entry); | |
636 | error = __radix_tree_insert(page_tree, index, | |
637 | dax_radix_order(new_entry), new_entry); | |
638 | if (error) { | |
639 | new_entry = ERR_PTR(error); | |
640 | goto unlock; | |
641 | } | |
642 | mapping->nrexceptional++; | |
643 | } else if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { | |
644 | /* | |
645 | * Only swap our new entry into the radix tree if the current | |
646 | * entry is a zero page or an empty entry. If a normal PTE or | |
647 | * PMD entry is already in the tree, we leave it alone. This | |
648 | * means that if we are trying to insert a PTE and the | |
649 | * existing entry is a PMD, we will just leave the PMD in the | |
650 | * tree and dirty it if necessary. | |
651 | */ | |
652 | struct radix_tree_node *node; | |
653 | void **slot; | |
654 | void *ret; | |
655 | ||
656 | ret = __radix_tree_lookup(page_tree, index, &node, &slot); | |
657 | WARN_ON_ONCE(ret != entry); | |
658 | __radix_tree_replace(page_tree, node, slot, | |
659 | new_entry, NULL, NULL); | |
660 | } | |
661 | if (vmf->flags & FAULT_FLAG_WRITE) | |
662 | radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); | |
663 | unlock: | |
664 | spin_unlock_irq(&mapping->tree_lock); | |
665 | if (hole_fill) { | |
666 | radix_tree_preload_end(); | |
667 | /* | |
668 | * We don't need hole page anymore, it has been replaced with | |
669 | * locked radix tree entry now. | |
670 | */ | |
671 | if (mapping->a_ops->freepage) | |
672 | mapping->a_ops->freepage(entry); | |
673 | unlock_page(entry); | |
674 | put_page(entry); | |
675 | } | |
676 | return new_entry; | |
677 | } | |
678 | ||
679 | static inline unsigned long | |
680 | pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma) | |
681 | { | |
682 | unsigned long address; | |
683 | ||
684 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
685 | VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); | |
686 | return address; | |
687 | } | |
688 | ||
689 | /* Walk all mappings of a given index of a file and writeprotect them */ | |
690 | static void dax_mapping_entry_mkclean(struct address_space *mapping, | |
691 | pgoff_t index, unsigned long pfn) | |
692 | { | |
693 | struct vm_area_struct *vma; | |
694 | pte_t pte, *ptep = NULL; | |
695 | pmd_t *pmdp = NULL; | |
696 | spinlock_t *ptl; | |
697 | bool changed; | |
698 | ||
699 | i_mmap_lock_read(mapping); | |
700 | vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) { | |
701 | unsigned long address; | |
702 | ||
703 | cond_resched(); | |
704 | ||
705 | if (!(vma->vm_flags & VM_SHARED)) | |
706 | continue; | |
707 | ||
708 | address = pgoff_address(index, vma); | |
709 | changed = false; | |
710 | if (follow_pte_pmd(vma->vm_mm, address, &ptep, &pmdp, &ptl)) | |
711 | continue; | |
712 | ||
713 | if (pmdp) { | |
714 | #ifdef CONFIG_FS_DAX_PMD | |
715 | pmd_t pmd; | |
716 | ||
717 | if (pfn != pmd_pfn(*pmdp)) | |
718 | goto unlock_pmd; | |
719 | if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp)) | |
720 | goto unlock_pmd; | |
721 | ||
722 | flush_cache_page(vma, address, pfn); | |
723 | pmd = pmdp_huge_clear_flush(vma, address, pmdp); | |
724 | pmd = pmd_wrprotect(pmd); | |
725 | pmd = pmd_mkclean(pmd); | |
726 | set_pmd_at(vma->vm_mm, address, pmdp, pmd); | |
727 | changed = true; | |
728 | unlock_pmd: | |
729 | spin_unlock(ptl); | |
730 | #endif | |
731 | } else { | |
732 | if (pfn != pte_pfn(*ptep)) | |
733 | goto unlock_pte; | |
734 | if (!pte_dirty(*ptep) && !pte_write(*ptep)) | |
735 | goto unlock_pte; | |
736 | ||
737 | flush_cache_page(vma, address, pfn); | |
738 | pte = ptep_clear_flush(vma, address, ptep); | |
739 | pte = pte_wrprotect(pte); | |
740 | pte = pte_mkclean(pte); | |
741 | set_pte_at(vma->vm_mm, address, ptep, pte); | |
742 | changed = true; | |
743 | unlock_pte: | |
744 | pte_unmap_unlock(ptep, ptl); | |
745 | } | |
746 | ||
747 | if (changed) | |
748 | mmu_notifier_invalidate_page(vma->vm_mm, address); | |
749 | } | |
750 | i_mmap_unlock_read(mapping); | |
751 | } | |
752 | ||
753 | static int dax_writeback_one(struct block_device *bdev, | |
754 | struct address_space *mapping, pgoff_t index, void *entry) | |
755 | { | |
756 | struct radix_tree_root *page_tree = &mapping->page_tree; | |
757 | struct blk_dax_ctl dax; | |
758 | void *entry2, **slot; | |
759 | int ret = 0; | |
760 | ||
761 | /* | |
762 | * A page got tagged dirty in DAX mapping? Something is seriously | |
763 | * wrong. | |
764 | */ | |
765 | if (WARN_ON(!radix_tree_exceptional_entry(entry))) | |
766 | return -EIO; | |
767 | ||
768 | spin_lock_irq(&mapping->tree_lock); | |
769 | entry2 = get_unlocked_mapping_entry(mapping, index, &slot); | |
770 | /* Entry got punched out / reallocated? */ | |
771 | if (!entry2 || !radix_tree_exceptional_entry(entry2)) | |
772 | goto put_unlocked; | |
773 | /* | |
774 | * Entry got reallocated elsewhere? No need to writeback. We have to | |
775 | * compare sectors as we must not bail out due to difference in lockbit | |
776 | * or entry type. | |
777 | */ | |
778 | if (dax_radix_sector(entry2) != dax_radix_sector(entry)) | |
779 | goto put_unlocked; | |
780 | if (WARN_ON_ONCE(dax_is_empty_entry(entry) || | |
781 | dax_is_zero_entry(entry))) { | |
782 | ret = -EIO; | |
783 | goto put_unlocked; | |
784 | } | |
785 | ||
786 | /* Another fsync thread may have already written back this entry */ | |
787 | if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) | |
788 | goto put_unlocked; | |
789 | /* Lock the entry to serialize with page faults */ | |
790 | entry = lock_slot(mapping, slot); | |
791 | /* | |
792 | * We can clear the tag now but we have to be careful so that concurrent | |
793 | * dax_writeback_one() calls for the same index cannot finish before we | |
794 | * actually flush the caches. This is achieved as the calls will look | |
795 | * at the entry only under tree_lock and once they do that they will | |
796 | * see the entry locked and wait for it to unlock. | |
797 | */ | |
798 | radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); | |
799 | spin_unlock_irq(&mapping->tree_lock); | |
800 | ||
801 | /* | |
802 | * Even if dax_writeback_mapping_range() was given a wbc->range_start | |
803 | * in the middle of a PMD, the 'index' we are given will be aligned to | |
804 | * the start index of the PMD, as will the sector we pull from | |
805 | * 'entry'. This allows us to flush for PMD_SIZE and not have to | |
806 | * worry about partial PMD writebacks. | |
807 | */ | |
808 | dax.sector = dax_radix_sector(entry); | |
809 | dax.size = PAGE_SIZE << dax_radix_order(entry); | |
810 | ||
811 | /* | |
812 | * We cannot hold tree_lock while calling dax_map_atomic() because it | |
813 | * eventually calls cond_resched(). | |
814 | */ | |
815 | ret = dax_map_atomic(bdev, &dax); | |
816 | if (ret < 0) { | |
817 | put_locked_mapping_entry(mapping, index, entry); | |
818 | return ret; | |
819 | } | |
820 | ||
821 | if (WARN_ON_ONCE(ret < dax.size)) { | |
822 | ret = -EIO; | |
823 | goto unmap; | |
824 | } | |
825 | ||
826 | dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn)); | |
827 | wb_cache_pmem(dax.addr, dax.size); | |
828 | /* | |
829 | * After we have flushed the cache, we can clear the dirty tag. There | |
830 | * cannot be new dirty data in the pfn after the flush has completed as | |
831 | * the pfn mappings are writeprotected and fault waits for mapping | |
832 | * entry lock. | |
833 | */ | |
834 | spin_lock_irq(&mapping->tree_lock); | |
835 | radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY); | |
836 | spin_unlock_irq(&mapping->tree_lock); | |
837 | unmap: | |
838 | dax_unmap_atomic(bdev, &dax); | |
839 | put_locked_mapping_entry(mapping, index, entry); | |
840 | return ret; | |
841 | ||
842 | put_unlocked: | |
843 | put_unlocked_mapping_entry(mapping, index, entry2); | |
844 | spin_unlock_irq(&mapping->tree_lock); | |
845 | return ret; | |
846 | } | |
847 | ||
848 | /* | |
849 | * Flush the mapping to the persistent domain within the byte range of [start, | |
850 | * end]. This is required by data integrity operations to ensure file data is | |
851 | * on persistent storage prior to completion of the operation. | |
852 | */ | |
853 | int dax_writeback_mapping_range(struct address_space *mapping, | |
854 | struct block_device *bdev, struct writeback_control *wbc) | |
855 | { | |
856 | struct inode *inode = mapping->host; | |
857 | pgoff_t start_index, end_index; | |
858 | pgoff_t indices[PAGEVEC_SIZE]; | |
859 | struct pagevec pvec; | |
860 | bool done = false; | |
861 | int i, ret = 0; | |
862 | ||
863 | if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) | |
864 | return -EIO; | |
865 | ||
866 | if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) | |
867 | return 0; | |
868 | ||
869 | start_index = wbc->range_start >> PAGE_SHIFT; | |
870 | end_index = wbc->range_end >> PAGE_SHIFT; | |
871 | ||
872 | tag_pages_for_writeback(mapping, start_index, end_index); | |
873 | ||
874 | pagevec_init(&pvec, 0); | |
875 | while (!done) { | |
876 | pvec.nr = find_get_entries_tag(mapping, start_index, | |
877 | PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE, | |
878 | pvec.pages, indices); | |
879 | ||
880 | if (pvec.nr == 0) | |
881 | break; | |
882 | ||
883 | for (i = 0; i < pvec.nr; i++) { | |
884 | if (indices[i] > end_index) { | |
885 | done = true; | |
886 | break; | |
887 | } | |
888 | ||
889 | ret = dax_writeback_one(bdev, mapping, indices[i], | |
890 | pvec.pages[i]); | |
891 | if (ret < 0) | |
892 | return ret; | |
893 | } | |
894 | } | |
895 | return 0; | |
896 | } | |
897 | EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); | |
898 | ||
899 | static int dax_insert_mapping(struct address_space *mapping, | |
900 | struct block_device *bdev, sector_t sector, size_t size, | |
901 | void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf) | |
902 | { | |
903 | unsigned long vaddr = vmf->address; | |
904 | struct blk_dax_ctl dax = { | |
905 | .sector = sector, | |
906 | .size = size, | |
907 | }; | |
908 | void *ret; | |
909 | void *entry = *entryp; | |
910 | ||
911 | if (dax_map_atomic(bdev, &dax) < 0) | |
912 | return PTR_ERR(dax.addr); | |
913 | dax_unmap_atomic(bdev, &dax); | |
914 | ||
915 | ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector, 0); | |
916 | if (IS_ERR(ret)) | |
917 | return PTR_ERR(ret); | |
918 | *entryp = ret; | |
919 | ||
920 | return vm_insert_mixed(vma, vaddr, dax.pfn); | |
921 | } | |
922 | ||
923 | /** | |
924 | * dax_pfn_mkwrite - handle first write to DAX page | |
925 | * @vma: The virtual memory area where the fault occurred | |
926 | * @vmf: The description of the fault | |
927 | */ | |
928 | int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) | |
929 | { | |
930 | struct file *file = vma->vm_file; | |
931 | struct address_space *mapping = file->f_mapping; | |
932 | void *entry, **slot; | |
933 | pgoff_t index = vmf->pgoff; | |
934 | ||
935 | spin_lock_irq(&mapping->tree_lock); | |
936 | entry = get_unlocked_mapping_entry(mapping, index, &slot); | |
937 | if (!entry || !radix_tree_exceptional_entry(entry)) { | |
938 | if (entry) | |
939 | put_unlocked_mapping_entry(mapping, index, entry); | |
940 | spin_unlock_irq(&mapping->tree_lock); | |
941 | return VM_FAULT_NOPAGE; | |
942 | } | |
943 | radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY); | |
944 | entry = lock_slot(mapping, slot); | |
945 | spin_unlock_irq(&mapping->tree_lock); | |
946 | /* | |
947 | * If we race with somebody updating the PTE and finish_mkwrite_fault() | |
948 | * fails, we don't care. We need to return VM_FAULT_NOPAGE and retry | |
949 | * the fault in either case. | |
950 | */ | |
951 | finish_mkwrite_fault(vmf); | |
952 | put_locked_mapping_entry(mapping, index, entry); | |
953 | return VM_FAULT_NOPAGE; | |
954 | } | |
955 | EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); | |
956 | ||
957 | static bool dax_range_is_aligned(struct block_device *bdev, | |
958 | unsigned int offset, unsigned int length) | |
959 | { | |
960 | unsigned short sector_size = bdev_logical_block_size(bdev); | |
961 | ||
962 | if (!IS_ALIGNED(offset, sector_size)) | |
963 | return false; | |
964 | if (!IS_ALIGNED(length, sector_size)) | |
965 | return false; | |
966 | ||
967 | return true; | |
968 | } | |
969 | ||
970 | int __dax_zero_page_range(struct block_device *bdev, sector_t sector, | |
971 | unsigned int offset, unsigned int length) | |
972 | { | |
973 | struct blk_dax_ctl dax = { | |
974 | .sector = sector, | |
975 | .size = PAGE_SIZE, | |
976 | }; | |
977 | ||
978 | if (dax_range_is_aligned(bdev, offset, length)) { | |
979 | sector_t start_sector = dax.sector + (offset >> 9); | |
980 | ||
981 | return blkdev_issue_zeroout(bdev, start_sector, | |
982 | length >> 9, GFP_NOFS, true); | |
983 | } else { | |
984 | if (dax_map_atomic(bdev, &dax) < 0) | |
985 | return PTR_ERR(dax.addr); | |
986 | clear_pmem(dax.addr + offset, length); | |
987 | dax_unmap_atomic(bdev, &dax); | |
988 | } | |
989 | return 0; | |
990 | } | |
991 | EXPORT_SYMBOL_GPL(__dax_zero_page_range); | |
992 | ||
993 | static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) | |
994 | { | |
995 | return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9); | |
996 | } | |
997 | ||
998 | static loff_t | |
999 | dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, | |
1000 | struct iomap *iomap) | |
1001 | { | |
1002 | struct iov_iter *iter = data; | |
1003 | loff_t end = pos + length, done = 0; | |
1004 | ssize_t ret = 0; | |
1005 | ||
1006 | if (iov_iter_rw(iter) == READ) { | |
1007 | end = min(end, i_size_read(inode)); | |
1008 | if (pos >= end) | |
1009 | return 0; | |
1010 | ||
1011 | if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) | |
1012 | return iov_iter_zero(min(length, end - pos), iter); | |
1013 | } | |
1014 | ||
1015 | if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED)) | |
1016 | return -EIO; | |
1017 | ||
1018 | /* | |
1019 | * Write can allocate block for an area which has a hole page mapped | |
1020 | * into page tables. We have to tear down these mappings so that data | |
1021 | * written by write(2) is visible in mmap. | |
1022 | */ | |
1023 | if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) { | |
1024 | invalidate_inode_pages2_range(inode->i_mapping, | |
1025 | pos >> PAGE_SHIFT, | |
1026 | (end - 1) >> PAGE_SHIFT); | |
1027 | } | |
1028 | ||
1029 | while (pos < end) { | |
1030 | unsigned offset = pos & (PAGE_SIZE - 1); | |
1031 | struct blk_dax_ctl dax = { 0 }; | |
1032 | ssize_t map_len; | |
1033 | ||
1034 | if (fatal_signal_pending(current)) { | |
1035 | ret = -EINTR; | |
1036 | break; | |
1037 | } | |
1038 | ||
1039 | dax.sector = dax_iomap_sector(iomap, pos); | |
1040 | dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK; | |
1041 | map_len = dax_map_atomic(iomap->bdev, &dax); | |
1042 | if (map_len < 0) { | |
1043 | ret = map_len; | |
1044 | break; | |
1045 | } | |
1046 | ||
1047 | dax.addr += offset; | |
1048 | map_len -= offset; | |
1049 | if (map_len > end - pos) | |
1050 | map_len = end - pos; | |
1051 | ||
1052 | if (iov_iter_rw(iter) == WRITE) | |
1053 | map_len = copy_from_iter_pmem(dax.addr, map_len, iter); | |
1054 | else | |
1055 | map_len = copy_to_iter(dax.addr, map_len, iter); | |
1056 | dax_unmap_atomic(iomap->bdev, &dax); | |
1057 | if (map_len <= 0) { | |
1058 | ret = map_len ? map_len : -EFAULT; | |
1059 | break; | |
1060 | } | |
1061 | ||
1062 | pos += map_len; | |
1063 | length -= map_len; | |
1064 | done += map_len; | |
1065 | } | |
1066 | ||
1067 | return done ? done : ret; | |
1068 | } | |
1069 | ||
1070 | /** | |
1071 | * dax_iomap_rw - Perform I/O to a DAX file | |
1072 | * @iocb: The control block for this I/O | |
1073 | * @iter: The addresses to do I/O from or to | |
1074 | * @ops: iomap ops passed from the file system | |
1075 | * | |
1076 | * This function performs read and write operations to directly mapped | |
1077 | * persistent memory. The callers needs to take care of read/write exclusion | |
1078 | * and evicting any page cache pages in the region under I/O. | |
1079 | */ | |
1080 | ssize_t | |
1081 | dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, | |
1082 | struct iomap_ops *ops) | |
1083 | { | |
1084 | struct address_space *mapping = iocb->ki_filp->f_mapping; | |
1085 | struct inode *inode = mapping->host; | |
1086 | loff_t pos = iocb->ki_pos, ret = 0, done = 0; | |
1087 | unsigned flags = 0; | |
1088 | ||
1089 | if (iov_iter_rw(iter) == WRITE) | |
1090 | flags |= IOMAP_WRITE; | |
1091 | ||
1092 | while (iov_iter_count(iter)) { | |
1093 | ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops, | |
1094 | iter, dax_iomap_actor); | |
1095 | if (ret <= 0) | |
1096 | break; | |
1097 | pos += ret; | |
1098 | done += ret; | |
1099 | } | |
1100 | ||
1101 | iocb->ki_pos += done; | |
1102 | return done ? done : ret; | |
1103 | } | |
1104 | EXPORT_SYMBOL_GPL(dax_iomap_rw); | |
1105 | ||
1106 | static int dax_fault_return(int error) | |
1107 | { | |
1108 | if (error == 0) | |
1109 | return VM_FAULT_NOPAGE; | |
1110 | if (error == -ENOMEM) | |
1111 | return VM_FAULT_OOM; | |
1112 | return VM_FAULT_SIGBUS; | |
1113 | } | |
1114 | ||
1115 | /** | |
1116 | * dax_iomap_fault - handle a page fault on a DAX file | |
1117 | * @vma: The virtual memory area where the fault occurred | |
1118 | * @vmf: The description of the fault | |
1119 | * @ops: iomap ops passed from the file system | |
1120 | * | |
1121 | * When a page fault occurs, filesystems may call this helper in their fault | |
1122 | * or mkwrite handler for DAX files. Assumes the caller has done all the | |
1123 | * necessary locking for the page fault to proceed successfully. | |
1124 | */ | |
1125 | int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, | |
1126 | struct iomap_ops *ops) | |
1127 | { | |
1128 | struct address_space *mapping = vma->vm_file->f_mapping; | |
1129 | struct inode *inode = mapping->host; | |
1130 | unsigned long vaddr = vmf->address; | |
1131 | loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; | |
1132 | sector_t sector; | |
1133 | struct iomap iomap = { 0 }; | |
1134 | unsigned flags = IOMAP_FAULT; | |
1135 | int error, major = 0; | |
1136 | int vmf_ret = 0; | |
1137 | void *entry; | |
1138 | ||
1139 | /* | |
1140 | * Check whether offset isn't beyond end of file now. Caller is supposed | |
1141 | * to hold locks serializing us with truncate / punch hole so this is | |
1142 | * a reliable test. | |
1143 | */ | |
1144 | if (pos >= i_size_read(inode)) | |
1145 | return VM_FAULT_SIGBUS; | |
1146 | ||
1147 | if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) | |
1148 | flags |= IOMAP_WRITE; | |
1149 | ||
1150 | /* | |
1151 | * Note that we don't bother to use iomap_apply here: DAX required | |
1152 | * the file system block size to be equal the page size, which means | |
1153 | * that we never have to deal with more than a single extent here. | |
1154 | */ | |
1155 | error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap); | |
1156 | if (error) | |
1157 | return dax_fault_return(error); | |
1158 | if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { | |
1159 | vmf_ret = dax_fault_return(-EIO); /* fs corruption? */ | |
1160 | goto finish_iomap; | |
1161 | } | |
1162 | ||
1163 | entry = grab_mapping_entry(mapping, vmf->pgoff, 0); | |
1164 | if (IS_ERR(entry)) { | |
1165 | vmf_ret = dax_fault_return(PTR_ERR(entry)); | |
1166 | goto finish_iomap; | |
1167 | } | |
1168 | ||
1169 | sector = dax_iomap_sector(&iomap, pos); | |
1170 | ||
1171 | if (vmf->cow_page) { | |
1172 | switch (iomap.type) { | |
1173 | case IOMAP_HOLE: | |
1174 | case IOMAP_UNWRITTEN: | |
1175 | clear_user_highpage(vmf->cow_page, vaddr); | |
1176 | break; | |
1177 | case IOMAP_MAPPED: | |
1178 | error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE, | |
1179 | vmf->cow_page, vaddr); | |
1180 | break; | |
1181 | default: | |
1182 | WARN_ON_ONCE(1); | |
1183 | error = -EIO; | |
1184 | break; | |
1185 | } | |
1186 | ||
1187 | if (error) | |
1188 | goto error_unlock_entry; | |
1189 | ||
1190 | __SetPageUptodate(vmf->cow_page); | |
1191 | vmf_ret = finish_fault(vmf); | |
1192 | if (!vmf_ret) | |
1193 | vmf_ret = VM_FAULT_DONE_COW; | |
1194 | goto unlock_entry; | |
1195 | } | |
1196 | ||
1197 | switch (iomap.type) { | |
1198 | case IOMAP_MAPPED: | |
1199 | if (iomap.flags & IOMAP_F_NEW) { | |
1200 | count_vm_event(PGMAJFAULT); | |
1201 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); | |
1202 | major = VM_FAULT_MAJOR; | |
1203 | } | |
1204 | error = dax_insert_mapping(mapping, iomap.bdev, sector, | |
1205 | PAGE_SIZE, &entry, vma, vmf); | |
1206 | /* -EBUSY is fine, somebody else faulted on the same PTE */ | |
1207 | if (error == -EBUSY) | |
1208 | error = 0; | |
1209 | break; | |
1210 | case IOMAP_UNWRITTEN: | |
1211 | case IOMAP_HOLE: | |
1212 | if (!(vmf->flags & FAULT_FLAG_WRITE)) { | |
1213 | vmf_ret = dax_load_hole(mapping, &entry, vmf); | |
1214 | goto unlock_entry; | |
1215 | } | |
1216 | /*FALLTHRU*/ | |
1217 | default: | |
1218 | WARN_ON_ONCE(1); | |
1219 | error = -EIO; | |
1220 | break; | |
1221 | } | |
1222 | ||
1223 | error_unlock_entry: | |
1224 | vmf_ret = dax_fault_return(error) | major; | |
1225 | unlock_entry: | |
1226 | put_locked_mapping_entry(mapping, vmf->pgoff, entry); | |
1227 | finish_iomap: | |
1228 | if (ops->iomap_end) { | |
1229 | int copied = PAGE_SIZE; | |
1230 | ||
1231 | if (vmf_ret & VM_FAULT_ERROR) | |
1232 | copied = 0; | |
1233 | /* | |
1234 | * The fault is done by now and there's no way back (other | |
1235 | * thread may be already happily using PTE we have installed). | |
1236 | * Just ignore error from ->iomap_end since we cannot do much | |
1237 | * with it. | |
1238 | */ | |
1239 | ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap); | |
1240 | } | |
1241 | return vmf_ret; | |
1242 | } | |
1243 | EXPORT_SYMBOL_GPL(dax_iomap_fault); | |
1244 | ||
1245 | #ifdef CONFIG_FS_DAX_PMD | |
1246 | /* | |
1247 | * The 'colour' (ie low bits) within a PMD of a page offset. This comes up | |
1248 | * more often than one might expect in the below functions. | |
1249 | */ | |
1250 | #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) | |
1251 | ||
1252 | static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd, | |
1253 | struct vm_fault *vmf, unsigned long address, | |
1254 | struct iomap *iomap, loff_t pos, bool write, void **entryp) | |
1255 | { | |
1256 | struct address_space *mapping = vma->vm_file->f_mapping; | |
1257 | struct block_device *bdev = iomap->bdev; | |
1258 | struct blk_dax_ctl dax = { | |
1259 | .sector = dax_iomap_sector(iomap, pos), | |
1260 | .size = PMD_SIZE, | |
1261 | }; | |
1262 | long length = dax_map_atomic(bdev, &dax); | |
1263 | void *ret; | |
1264 | ||
1265 | if (length < 0) /* dax_map_atomic() failed */ | |
1266 | return VM_FAULT_FALLBACK; | |
1267 | if (length < PMD_SIZE) | |
1268 | goto unmap_fallback; | |
1269 | if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) | |
1270 | goto unmap_fallback; | |
1271 | if (!pfn_t_devmap(dax.pfn)) | |
1272 | goto unmap_fallback; | |
1273 | ||
1274 | dax_unmap_atomic(bdev, &dax); | |
1275 | ||
1276 | ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector, | |
1277 | RADIX_DAX_PMD); | |
1278 | if (IS_ERR(ret)) | |
1279 | return VM_FAULT_FALLBACK; | |
1280 | *entryp = ret; | |
1281 | ||
1282 | return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write); | |
1283 | ||
1284 | unmap_fallback: | |
1285 | dax_unmap_atomic(bdev, &dax); | |
1286 | return VM_FAULT_FALLBACK; | |
1287 | } | |
1288 | ||
1289 | static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd, | |
1290 | struct vm_fault *vmf, unsigned long address, | |
1291 | struct iomap *iomap, void **entryp) | |
1292 | { | |
1293 | struct address_space *mapping = vma->vm_file->f_mapping; | |
1294 | unsigned long pmd_addr = address & PMD_MASK; | |
1295 | struct page *zero_page; | |
1296 | spinlock_t *ptl; | |
1297 | pmd_t pmd_entry; | |
1298 | void *ret; | |
1299 | ||
1300 | zero_page = mm_get_huge_zero_page(vma->vm_mm); | |
1301 | ||
1302 | if (unlikely(!zero_page)) | |
1303 | return VM_FAULT_FALLBACK; | |
1304 | ||
1305 | ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0, | |
1306 | RADIX_DAX_PMD | RADIX_DAX_HZP); | |
1307 | if (IS_ERR(ret)) | |
1308 | return VM_FAULT_FALLBACK; | |
1309 | *entryp = ret; | |
1310 | ||
1311 | ptl = pmd_lock(vma->vm_mm, pmd); | |
1312 | if (!pmd_none(*pmd)) { | |
1313 | spin_unlock(ptl); | |
1314 | return VM_FAULT_FALLBACK; | |
1315 | } | |
1316 | ||
1317 | pmd_entry = mk_pmd(zero_page, vma->vm_page_prot); | |
1318 | pmd_entry = pmd_mkhuge(pmd_entry); | |
1319 | set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry); | |
1320 | spin_unlock(ptl); | |
1321 | return VM_FAULT_NOPAGE; | |
1322 | } | |
1323 | ||
1324 | int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address, | |
1325 | pmd_t *pmd, unsigned int flags, struct iomap_ops *ops) | |
1326 | { | |
1327 | struct address_space *mapping = vma->vm_file->f_mapping; | |
1328 | unsigned long pmd_addr = address & PMD_MASK; | |
1329 | bool write = flags & FAULT_FLAG_WRITE; | |
1330 | unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT; | |
1331 | struct inode *inode = mapping->host; | |
1332 | int result = VM_FAULT_FALLBACK; | |
1333 | struct iomap iomap = { 0 }; | |
1334 | pgoff_t max_pgoff, pgoff; | |
1335 | struct vm_fault vmf; | |
1336 | void *entry; | |
1337 | loff_t pos; | |
1338 | int error; | |
1339 | ||
1340 | /* Fall back to PTEs if we're going to COW */ | |
1341 | if (write && !(vma->vm_flags & VM_SHARED)) | |
1342 | goto fallback; | |
1343 | ||
1344 | /* If the PMD would extend outside the VMA */ | |
1345 | if (pmd_addr < vma->vm_start) | |
1346 | goto fallback; | |
1347 | if ((pmd_addr + PMD_SIZE) > vma->vm_end) | |
1348 | goto fallback; | |
1349 | ||
1350 | /* | |
1351 | * Check whether offset isn't beyond end of file now. Caller is | |
1352 | * supposed to hold locks serializing us with truncate / punch hole so | |
1353 | * this is a reliable test. | |
1354 | */ | |
1355 | pgoff = linear_page_index(vma, pmd_addr); | |
1356 | max_pgoff = (i_size_read(inode) - 1) >> PAGE_SHIFT; | |
1357 | ||
1358 | if (pgoff > max_pgoff) | |
1359 | return VM_FAULT_SIGBUS; | |
1360 | ||
1361 | /* If the PMD would extend beyond the file size */ | |
1362 | if ((pgoff | PG_PMD_COLOUR) > max_pgoff) | |
1363 | goto fallback; | |
1364 | ||
1365 | /* | |
1366 | * Note that we don't use iomap_apply here. We aren't doing I/O, only | |
1367 | * setting up a mapping, so really we're using iomap_begin() as a way | |
1368 | * to look up our filesystem block. | |
1369 | */ | |
1370 | pos = (loff_t)pgoff << PAGE_SHIFT; | |
1371 | error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap); | |
1372 | if (error) | |
1373 | goto fallback; | |
1374 | ||
1375 | if (iomap.offset + iomap.length < pos + PMD_SIZE) | |
1376 | goto finish_iomap; | |
1377 | ||
1378 | /* | |
1379 | * grab_mapping_entry() will make sure we get a 2M empty entry, a DAX | |
1380 | * PMD or a HZP entry. If it can't (because a 4k page is already in | |
1381 | * the tree, for instance), it will return -EEXIST and we just fall | |
1382 | * back to 4k entries. | |
1383 | */ | |
1384 | entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD); | |
1385 | if (IS_ERR(entry)) | |
1386 | goto finish_iomap; | |
1387 | ||
1388 | vmf.pgoff = pgoff; | |
1389 | vmf.flags = flags; | |
1390 | vmf.gfp_mask = mapping_gfp_mask(mapping) | __GFP_IO; | |
1391 | ||
1392 | switch (iomap.type) { | |
1393 | case IOMAP_MAPPED: | |
1394 | result = dax_pmd_insert_mapping(vma, pmd, &vmf, address, | |
1395 | &iomap, pos, write, &entry); | |
1396 | break; | |
1397 | case IOMAP_UNWRITTEN: | |
1398 | case IOMAP_HOLE: | |
1399 | if (WARN_ON_ONCE(write)) | |
1400 | goto unlock_entry; | |
1401 | result = dax_pmd_load_hole(vma, pmd, &vmf, address, &iomap, | |
1402 | &entry); | |
1403 | break; | |
1404 | default: | |
1405 | WARN_ON_ONCE(1); | |
1406 | break; | |
1407 | } | |
1408 | ||
1409 | unlock_entry: | |
1410 | put_locked_mapping_entry(mapping, pgoff, entry); | |
1411 | finish_iomap: | |
1412 | if (ops->iomap_end) { | |
1413 | int copied = PMD_SIZE; | |
1414 | ||
1415 | if (result == VM_FAULT_FALLBACK) | |
1416 | copied = 0; | |
1417 | /* | |
1418 | * The fault is done by now and there's no way back (other | |
1419 | * thread may be already happily using PMD we have installed). | |
1420 | * Just ignore error from ->iomap_end since we cannot do much | |
1421 | * with it. | |
1422 | */ | |
1423 | ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags, | |
1424 | &iomap); | |
1425 | } | |
1426 | fallback: | |
1427 | if (result == VM_FAULT_FALLBACK) { | |
1428 | split_huge_pmd(vma, pmd, address); | |
1429 | count_vm_event(THP_FAULT_FALLBACK); | |
1430 | } | |
1431 | return result; | |
1432 | } | |
1433 | EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault); | |
1434 | #endif /* CONFIG_FS_DAX_PMD */ |