blob: 71f87d74afe126dc86c76e99b4961881eb468459
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/iomap.h> |
35 | #include "internal.h" |
36 | |
37 | /* |
38 | * We use lowest available bit in exceptional entry for locking, other two |
39 | * bits to determine entry type. In total 3 special bits. |
40 | */ |
41 | #define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3) |
42 | #define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) |
43 | #define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) |
44 | #define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD) |
45 | #define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK) |
46 | #define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT)) |
47 | #define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \ |
48 | RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \ |
49 | RADIX_TREE_EXCEPTIONAL_ENTRY)) |
50 | |
51 | /* We choose 4096 entries - same as per-zone page wait tables */ |
52 | #define DAX_WAIT_TABLE_BITS 12 |
53 | #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS) |
54 | |
55 | wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; |
56 | |
57 | static int __init init_dax_wait_table(void) |
58 | { |
59 | int i; |
60 | |
61 | for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++) |
62 | init_waitqueue_head(wait_table + i); |
63 | return 0; |
64 | } |
65 | fs_initcall(init_dax_wait_table); |
66 | |
67 | static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping, |
68 | pgoff_t index) |
69 | { |
70 | unsigned long hash = hash_long((unsigned long)mapping ^ index, |
71 | DAX_WAIT_TABLE_BITS); |
72 | return wait_table + hash; |
73 | } |
74 | |
75 | static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax) |
76 | { |
77 | struct request_queue *q = bdev->bd_queue; |
78 | long rc = -EIO; |
79 | |
80 | dax->addr = ERR_PTR(-EIO); |
81 | if (blk_queue_enter(q, true) != 0) |
82 | return rc; |
83 | |
84 | rc = bdev_direct_access(bdev, dax); |
85 | if (rc < 0) { |
86 | dax->addr = ERR_PTR(rc); |
87 | blk_queue_exit(q); |
88 | return rc; |
89 | } |
90 | return rc; |
91 | } |
92 | |
93 | static void dax_unmap_atomic(struct block_device *bdev, |
94 | const struct blk_dax_ctl *dax) |
95 | { |
96 | if (IS_ERR(dax->addr)) |
97 | return; |
98 | blk_queue_exit(bdev->bd_queue); |
99 | } |
100 | |
101 | struct page *read_dax_sector(struct block_device *bdev, sector_t n) |
102 | { |
103 | struct page *page = alloc_pages(GFP_KERNEL, 0); |
104 | struct blk_dax_ctl dax = { |
105 | .size = PAGE_SIZE, |
106 | .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), |
107 | }; |
108 | long rc; |
109 | |
110 | if (!page) |
111 | return ERR_PTR(-ENOMEM); |
112 | |
113 | rc = dax_map_atomic(bdev, &dax); |
114 | if (rc < 0) |
115 | return ERR_PTR(rc); |
116 | memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE); |
117 | dax_unmap_atomic(bdev, &dax); |
118 | return page; |
119 | } |
120 | |
121 | static bool buffer_written(struct buffer_head *bh) |
122 | { |
123 | return buffer_mapped(bh) && !buffer_unwritten(bh); |
124 | } |
125 | |
126 | /* |
127 | * When ext4 encounters a hole, it returns without modifying the buffer_head |
128 | * which means that we can't trust b_size. To cope with this, we set b_state |
129 | * to 0 before calling get_block and, if any bit is set, we know we can trust |
130 | * b_size. Unfortunate, really, since ext4 knows precisely how long a hole is |
131 | * and would save us time calling get_block repeatedly. |
132 | */ |
133 | static bool buffer_size_valid(struct buffer_head *bh) |
134 | { |
135 | return bh->b_state != 0; |
136 | } |
137 | |
138 | |
139 | static sector_t to_sector(const struct buffer_head *bh, |
140 | const struct inode *inode) |
141 | { |
142 | sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9); |
143 | |
144 | return sector; |
145 | } |
146 | |
147 | static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, |
148 | loff_t start, loff_t end, get_block_t get_block, |
149 | struct buffer_head *bh) |
150 | { |
151 | loff_t pos = start, max = start, bh_max = start; |
152 | bool hole = false; |
153 | struct block_device *bdev = NULL; |
154 | int rw = iov_iter_rw(iter), rc; |
155 | long map_len = 0; |
156 | struct blk_dax_ctl dax = { |
157 | .addr = ERR_PTR(-EIO), |
158 | }; |
159 | unsigned blkbits = inode->i_blkbits; |
160 | sector_t file_blks = (i_size_read(inode) + (1 << blkbits) - 1) |
161 | >> blkbits; |
162 | |
163 | if (rw == READ) |
164 | end = min(end, i_size_read(inode)); |
165 | |
166 | while (pos < end) { |
167 | size_t len; |
168 | if (pos == max) { |
169 | long page = pos >> PAGE_SHIFT; |
170 | sector_t block = page << (PAGE_SHIFT - blkbits); |
171 | unsigned first = pos - (block << blkbits); |
172 | long size; |
173 | |
174 | if (pos == bh_max) { |
175 | bh->b_size = PAGE_ALIGN(end - pos); |
176 | bh->b_state = 0; |
177 | rc = get_block(inode, block, bh, rw == WRITE); |
178 | if (rc) |
179 | break; |
180 | if (!buffer_size_valid(bh)) |
181 | bh->b_size = 1 << blkbits; |
182 | bh_max = pos - first + bh->b_size; |
183 | bdev = bh->b_bdev; |
184 | /* |
185 | * We allow uninitialized buffers for writes |
186 | * beyond EOF as those cannot race with faults |
187 | */ |
188 | WARN_ON_ONCE( |
189 | (buffer_new(bh) && block < file_blks) || |
190 | (rw == WRITE && buffer_unwritten(bh))); |
191 | } else { |
192 | unsigned done = bh->b_size - |
193 | (bh_max - (pos - first)); |
194 | bh->b_blocknr += done >> blkbits; |
195 | bh->b_size -= done; |
196 | } |
197 | |
198 | hole = rw == READ && !buffer_written(bh); |
199 | if (hole) { |
200 | size = bh->b_size - first; |
201 | } else { |
202 | dax_unmap_atomic(bdev, &dax); |
203 | dax.sector = to_sector(bh, inode); |
204 | dax.size = bh->b_size; |
205 | map_len = dax_map_atomic(bdev, &dax); |
206 | if (map_len < 0) { |
207 | rc = map_len; |
208 | break; |
209 | } |
210 | dax.addr += first; |
211 | size = map_len - first; |
212 | } |
213 | /* |
214 | * pos + size is one past the last offset for IO, |
215 | * so pos + size can overflow loff_t at extreme offsets. |
216 | * Cast to u64 to catch this and get the true minimum. |
217 | */ |
218 | max = min_t(u64, pos + size, end); |
219 | } |
220 | |
221 | if (iov_iter_rw(iter) == WRITE) { |
222 | len = copy_from_iter_pmem(dax.addr, max - pos, iter); |
223 | } else if (!hole) |
224 | len = copy_to_iter((void __force *) dax.addr, max - pos, |
225 | iter); |
226 | else |
227 | len = iov_iter_zero(max - pos, iter); |
228 | |
229 | if (!len) { |
230 | rc = -EFAULT; |
231 | break; |
232 | } |
233 | |
234 | pos += len; |
235 | if (!IS_ERR(dax.addr)) |
236 | dax.addr += len; |
237 | } |
238 | |
239 | dax_unmap_atomic(bdev, &dax); |
240 | |
241 | return (pos == start) ? rc : pos - start; |
242 | } |
243 | |
244 | /** |
245 | * dax_do_io - Perform I/O to a DAX file |
246 | * @iocb: The control block for this I/O |
247 | * @inode: The file which the I/O is directed at |
248 | * @iter: The addresses to do I/O from or to |
249 | * @get_block: The filesystem method used to translate file offsets to blocks |
250 | * @end_io: A filesystem callback for I/O completion |
251 | * @flags: See below |
252 | * |
253 | * This function uses the same locking scheme as do_blockdev_direct_IO: |
254 | * If @flags has DIO_LOCKING set, we assume that the i_mutex is held by the |
255 | * caller for writes. For reads, we take and release the i_mutex ourselves. |
256 | * If DIO_LOCKING is not set, the filesystem takes care of its own locking. |
257 | * As with do_blockdev_direct_IO(), we increment i_dio_count while the I/O |
258 | * is in progress. |
259 | */ |
260 | ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, |
261 | struct iov_iter *iter, get_block_t get_block, |
262 | dio_iodone_t end_io, int flags) |
263 | { |
264 | struct buffer_head bh; |
265 | ssize_t retval = -EINVAL; |
266 | loff_t pos = iocb->ki_pos; |
267 | loff_t end = pos + iov_iter_count(iter); |
268 | |
269 | memset(&bh, 0, sizeof(bh)); |
270 | bh.b_bdev = inode->i_sb->s_bdev; |
271 | |
272 | if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) |
273 | inode_lock(inode); |
274 | |
275 | /* Protects against truncate */ |
276 | if (!(flags & DIO_SKIP_DIO_COUNT)) |
277 | inode_dio_begin(inode); |
278 | |
279 | retval = dax_io(inode, iter, pos, end, get_block, &bh); |
280 | |
281 | if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) |
282 | inode_unlock(inode); |
283 | |
284 | if (end_io) { |
285 | int err; |
286 | |
287 | err = end_io(iocb, pos, retval, bh.b_private); |
288 | if (err) |
289 | retval = err; |
290 | } |
291 | |
292 | if (!(flags & DIO_SKIP_DIO_COUNT)) |
293 | inode_dio_end(inode); |
294 | return retval; |
295 | } |
296 | EXPORT_SYMBOL_GPL(dax_do_io); |
297 | |
298 | /* |
299 | * DAX radix tree locking |
300 | */ |
301 | struct exceptional_entry_key { |
302 | struct address_space *mapping; |
303 | unsigned long index; |
304 | }; |
305 | |
306 | struct wait_exceptional_entry_queue { |
307 | wait_queue_t wait; |
308 | struct exceptional_entry_key key; |
309 | }; |
310 | |
311 | static int wake_exceptional_entry_func(wait_queue_t *wait, unsigned int mode, |
312 | int sync, void *keyp) |
313 | { |
314 | struct exceptional_entry_key *key = keyp; |
315 | struct wait_exceptional_entry_queue *ewait = |
316 | container_of(wait, struct wait_exceptional_entry_queue, wait); |
317 | |
318 | if (key->mapping != ewait->key.mapping || |
319 | key->index != ewait->key.index) |
320 | return 0; |
321 | return autoremove_wake_function(wait, mode, sync, NULL); |
322 | } |
323 | |
324 | /* |
325 | * Check whether the given slot is locked. The function must be called with |
326 | * mapping->tree_lock held |
327 | */ |
328 | static inline int slot_locked(struct address_space *mapping, void **slot) |
329 | { |
330 | unsigned long entry = (unsigned long) |
331 | radix_tree_deref_slot_protected(slot, &mapping->tree_lock); |
332 | return entry & RADIX_DAX_ENTRY_LOCK; |
333 | } |
334 | |
335 | /* |
336 | * Mark the given slot is locked. The function must be called with |
337 | * mapping->tree_lock held |
338 | */ |
339 | static inline void *lock_slot(struct address_space *mapping, void **slot) |
340 | { |
341 | unsigned long entry = (unsigned long) |
342 | radix_tree_deref_slot_protected(slot, &mapping->tree_lock); |
343 | |
344 | entry |= RADIX_DAX_ENTRY_LOCK; |
345 | radix_tree_replace_slot(slot, (void *)entry); |
346 | return (void *)entry; |
347 | } |
348 | |
349 | /* |
350 | * Mark the given slot is unlocked. The function must be called with |
351 | * mapping->tree_lock held |
352 | */ |
353 | static inline void *unlock_slot(struct address_space *mapping, void **slot) |
354 | { |
355 | unsigned long entry = (unsigned long) |
356 | radix_tree_deref_slot_protected(slot, &mapping->tree_lock); |
357 | |
358 | entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK; |
359 | radix_tree_replace_slot(slot, (void *)entry); |
360 | return (void *)entry; |
361 | } |
362 | |
363 | /* |
364 | * Lookup entry in radix tree, wait for it to become unlocked if it is |
365 | * exceptional entry and return it. The caller must call |
366 | * put_unlocked_mapping_entry() when he decided not to lock the entry or |
367 | * put_locked_mapping_entry() when he locked the entry and now wants to |
368 | * unlock it. |
369 | * |
370 | * The function must be called with mapping->tree_lock held. |
371 | */ |
372 | static void *get_unlocked_mapping_entry(struct address_space *mapping, |
373 | pgoff_t index, void ***slotp) |
374 | { |
375 | void *ret, **slot; |
376 | struct wait_exceptional_entry_queue ewait; |
377 | wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index); |
378 | |
379 | init_wait(&ewait.wait); |
380 | ewait.wait.func = wake_exceptional_entry_func; |
381 | ewait.key.mapping = mapping; |
382 | ewait.key.index = index; |
383 | |
384 | for (;;) { |
385 | ret = __radix_tree_lookup(&mapping->page_tree, index, NULL, |
386 | &slot); |
387 | if (!ret || !radix_tree_exceptional_entry(ret) || |
388 | !slot_locked(mapping, slot)) { |
389 | if (slotp) |
390 | *slotp = slot; |
391 | return ret; |
392 | } |
393 | prepare_to_wait_exclusive(wq, &ewait.wait, |
394 | TASK_UNINTERRUPTIBLE); |
395 | spin_unlock_irq(&mapping->tree_lock); |
396 | schedule(); |
397 | finish_wait(wq, &ewait.wait); |
398 | spin_lock_irq(&mapping->tree_lock); |
399 | } |
400 | } |
401 | |
402 | /* |
403 | * Find radix tree entry at given index. If it points to a page, return with |
404 | * the page locked. If it points to the exceptional entry, return with the |
405 | * radix tree entry locked. If the radix tree doesn't contain given index, |
406 | * create empty exceptional entry for the index and return with it locked. |
407 | * |
408 | * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For |
409 | * persistent memory the benefit is doubtful. We can add that later if we can |
410 | * show it helps. |
411 | */ |
412 | static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index) |
413 | { |
414 | void *ret, **slot; |
415 | |
416 | restart: |
417 | spin_lock_irq(&mapping->tree_lock); |
418 | ret = get_unlocked_mapping_entry(mapping, index, &slot); |
419 | /* No entry for given index? Make sure radix tree is big enough. */ |
420 | if (!ret) { |
421 | int err; |
422 | |
423 | spin_unlock_irq(&mapping->tree_lock); |
424 | err = radix_tree_preload( |
425 | mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM); |
426 | if (err) |
427 | return ERR_PTR(err); |
428 | ret = (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | |
429 | RADIX_DAX_ENTRY_LOCK); |
430 | spin_lock_irq(&mapping->tree_lock); |
431 | err = radix_tree_insert(&mapping->page_tree, index, ret); |
432 | radix_tree_preload_end(); |
433 | if (err) { |
434 | spin_unlock_irq(&mapping->tree_lock); |
435 | /* Someone already created the entry? */ |
436 | if (err == -EEXIST) |
437 | goto restart; |
438 | return ERR_PTR(err); |
439 | } |
440 | /* Good, we have inserted empty locked entry into the tree. */ |
441 | mapping->nrexceptional++; |
442 | spin_unlock_irq(&mapping->tree_lock); |
443 | return ret; |
444 | } |
445 | /* Normal page in radix tree? */ |
446 | if (!radix_tree_exceptional_entry(ret)) { |
447 | struct page *page = ret; |
448 | |
449 | get_page(page); |
450 | spin_unlock_irq(&mapping->tree_lock); |
451 | lock_page(page); |
452 | /* Page got truncated? Retry... */ |
453 | if (unlikely(page->mapping != mapping)) { |
454 | unlock_page(page); |
455 | put_page(page); |
456 | goto restart; |
457 | } |
458 | return page; |
459 | } |
460 | ret = lock_slot(mapping, slot); |
461 | spin_unlock_irq(&mapping->tree_lock); |
462 | return ret; |
463 | } |
464 | |
465 | void dax_wake_mapping_entry_waiter(struct address_space *mapping, |
466 | pgoff_t index, bool wake_all) |
467 | { |
468 | wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index); |
469 | |
470 | /* |
471 | * Checking for locked entry and prepare_to_wait_exclusive() happens |
472 | * under mapping->tree_lock, ditto for entry handling in our callers. |
473 | * So at this point all tasks that could have seen our entry locked |
474 | * must be in the waitqueue and the following check will see them. |
475 | */ |
476 | if (waitqueue_active(wq)) { |
477 | struct exceptional_entry_key key; |
478 | |
479 | key.mapping = mapping; |
480 | key.index = index; |
481 | __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key); |
482 | } |
483 | } |
484 | |
485 | void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index) |
486 | { |
487 | void *ret, **slot; |
488 | |
489 | spin_lock_irq(&mapping->tree_lock); |
490 | ret = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot); |
491 | if (WARN_ON_ONCE(!ret || !radix_tree_exceptional_entry(ret) || |
492 | !slot_locked(mapping, slot))) { |
493 | spin_unlock_irq(&mapping->tree_lock); |
494 | return; |
495 | } |
496 | unlock_slot(mapping, slot); |
497 | spin_unlock_irq(&mapping->tree_lock); |
498 | dax_wake_mapping_entry_waiter(mapping, index, false); |
499 | } |
500 | |
501 | static void put_locked_mapping_entry(struct address_space *mapping, |
502 | pgoff_t index, void *entry) |
503 | { |
504 | if (!radix_tree_exceptional_entry(entry)) { |
505 | unlock_page(entry); |
506 | put_page(entry); |
507 | } else { |
508 | dax_unlock_mapping_entry(mapping, index); |
509 | } |
510 | } |
511 | |
512 | /* |
513 | * Called when we are done with radix tree entry we looked up via |
514 | * get_unlocked_mapping_entry() and which we didn't lock in the end. |
515 | */ |
516 | static void put_unlocked_mapping_entry(struct address_space *mapping, |
517 | pgoff_t index, void *entry) |
518 | { |
519 | if (!radix_tree_exceptional_entry(entry)) |
520 | return; |
521 | |
522 | /* We have to wake up next waiter for the radix tree entry lock */ |
523 | dax_wake_mapping_entry_waiter(mapping, index, false); |
524 | } |
525 | |
526 | /* |
527 | * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree |
528 | * entry to get unlocked before deleting it. |
529 | */ |
530 | int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) |
531 | { |
532 | void *entry; |
533 | |
534 | spin_lock_irq(&mapping->tree_lock); |
535 | entry = get_unlocked_mapping_entry(mapping, index, NULL); |
536 | /* |
537 | * This gets called from truncate / punch_hole path. As such, the caller |
538 | * must hold locks protecting against concurrent modifications of the |
539 | * radix tree (usually fs-private i_mmap_sem for writing). Since the |
540 | * caller has seen exceptional entry for this index, we better find it |
541 | * at that index as well... |
542 | */ |
543 | if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry))) { |
544 | spin_unlock_irq(&mapping->tree_lock); |
545 | return 0; |
546 | } |
547 | radix_tree_delete(&mapping->page_tree, index); |
548 | mapping->nrexceptional--; |
549 | spin_unlock_irq(&mapping->tree_lock); |
550 | dax_wake_mapping_entry_waiter(mapping, index, true); |
551 | |
552 | return 1; |
553 | } |
554 | |
555 | /* |
556 | * The user has performed a load from a hole in the file. Allocating |
557 | * a new page in the file would cause excessive storage usage for |
558 | * workloads with sparse files. We allocate a page cache page instead. |
559 | * We'll kick it out of the page cache if it's ever written to, |
560 | * otherwise it will simply fall out of the page cache under memory |
561 | * pressure without ever having been dirtied. |
562 | */ |
563 | static int dax_load_hole(struct address_space *mapping, void *entry, |
564 | struct vm_fault *vmf) |
565 | { |
566 | struct page *page; |
567 | |
568 | /* Hole page already exists? Return it... */ |
569 | if (!radix_tree_exceptional_entry(entry)) { |
570 | vmf->page = entry; |
571 | return VM_FAULT_LOCKED; |
572 | } |
573 | |
574 | /* This will replace locked radix tree entry with a hole page */ |
575 | page = find_or_create_page(mapping, vmf->pgoff, |
576 | vmf->gfp_mask | __GFP_ZERO); |
577 | if (!page) { |
578 | put_locked_mapping_entry(mapping, vmf->pgoff, entry); |
579 | return VM_FAULT_OOM; |
580 | } |
581 | vmf->page = page; |
582 | return VM_FAULT_LOCKED; |
583 | } |
584 | |
585 | static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size, |
586 | struct page *to, unsigned long vaddr) |
587 | { |
588 | struct blk_dax_ctl dax = { |
589 | .sector = sector, |
590 | .size = size, |
591 | }; |
592 | void *vto; |
593 | |
594 | if (dax_map_atomic(bdev, &dax) < 0) |
595 | return PTR_ERR(dax.addr); |
596 | vto = kmap_atomic(to); |
597 | copy_user_page(vto, (void __force *)dax.addr, vaddr, to); |
598 | kunmap_atomic(vto); |
599 | dax_unmap_atomic(bdev, &dax); |
600 | return 0; |
601 | } |
602 | |
603 | #define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_SHIFT)) |
604 | |
605 | static void *dax_insert_mapping_entry(struct address_space *mapping, |
606 | struct vm_fault *vmf, |
607 | void *entry, sector_t sector) |
608 | { |
609 | struct radix_tree_root *page_tree = &mapping->page_tree; |
610 | int error = 0; |
611 | bool hole_fill = false; |
612 | void *new_entry; |
613 | pgoff_t index = vmf->pgoff; |
614 | |
615 | if (vmf->flags & FAULT_FLAG_WRITE) |
616 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
617 | |
618 | /* Replacing hole page with block mapping? */ |
619 | if (!radix_tree_exceptional_entry(entry)) { |
620 | hole_fill = true; |
621 | /* |
622 | * Unmap the page now before we remove it from page cache below. |
623 | * The page is locked so it cannot be faulted in again. |
624 | */ |
625 | unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, |
626 | PAGE_SIZE, 0); |
627 | error = radix_tree_preload(vmf->gfp_mask & ~__GFP_HIGHMEM); |
628 | if (error) |
629 | return ERR_PTR(error); |
630 | } |
631 | |
632 | spin_lock_irq(&mapping->tree_lock); |
633 | new_entry = (void *)((unsigned long)RADIX_DAX_ENTRY(sector, false) | |
634 | RADIX_DAX_ENTRY_LOCK); |
635 | if (hole_fill) { |
636 | __delete_from_page_cache(entry, NULL); |
637 | /* Drop pagecache reference */ |
638 | put_page(entry); |
639 | error = radix_tree_insert(page_tree, index, new_entry); |
640 | if (error) { |
641 | new_entry = ERR_PTR(error); |
642 | goto unlock; |
643 | } |
644 | mapping->nrexceptional++; |
645 | } else { |
646 | void **slot; |
647 | void *ret; |
648 | |
649 | ret = __radix_tree_lookup(page_tree, index, NULL, &slot); |
650 | WARN_ON_ONCE(ret != entry); |
651 | radix_tree_replace_slot(slot, new_entry); |
652 | } |
653 | if (vmf->flags & FAULT_FLAG_WRITE) |
654 | radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); |
655 | unlock: |
656 | spin_unlock_irq(&mapping->tree_lock); |
657 | if (hole_fill) { |
658 | radix_tree_preload_end(); |
659 | /* |
660 | * We don't need hole page anymore, it has been replaced with |
661 | * locked radix tree entry now. |
662 | */ |
663 | if (mapping->a_ops->freepage) |
664 | mapping->a_ops->freepage(entry); |
665 | unlock_page(entry); |
666 | put_page(entry); |
667 | } |
668 | return new_entry; |
669 | } |
670 | |
671 | static int dax_writeback_one(struct block_device *bdev, |
672 | struct address_space *mapping, pgoff_t index, void *entry) |
673 | { |
674 | struct radix_tree_root *page_tree = &mapping->page_tree; |
675 | int type = RADIX_DAX_TYPE(entry); |
676 | struct radix_tree_node *node; |
677 | struct blk_dax_ctl dax; |
678 | void **slot; |
679 | int ret = 0; |
680 | |
681 | spin_lock_irq(&mapping->tree_lock); |
682 | /* |
683 | * Regular page slots are stabilized by the page lock even |
684 | * without the tree itself locked. These unlocked entries |
685 | * need verification under the tree lock. |
686 | */ |
687 | if (!__radix_tree_lookup(page_tree, index, &node, &slot)) |
688 | goto unlock; |
689 | if (*slot != entry) |
690 | goto unlock; |
691 | |
692 | /* another fsync thread may have already written back this entry */ |
693 | if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) |
694 | goto unlock; |
695 | |
696 | if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) { |
697 | ret = -EIO; |
698 | goto unlock; |
699 | } |
700 | |
701 | dax.sector = RADIX_DAX_SECTOR(entry); |
702 | dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE); |
703 | spin_unlock_irq(&mapping->tree_lock); |
704 | |
705 | /* |
706 | * We cannot hold tree_lock while calling dax_map_atomic() because it |
707 | * eventually calls cond_resched(). |
708 | */ |
709 | ret = dax_map_atomic(bdev, &dax); |
710 | if (ret < 0) |
711 | return ret; |
712 | |
713 | if (WARN_ON_ONCE(ret < dax.size)) { |
714 | ret = -EIO; |
715 | goto unmap; |
716 | } |
717 | |
718 | wb_cache_pmem(dax.addr, dax.size); |
719 | |
720 | spin_lock_irq(&mapping->tree_lock); |
721 | radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); |
722 | spin_unlock_irq(&mapping->tree_lock); |
723 | unmap: |
724 | dax_unmap_atomic(bdev, &dax); |
725 | return ret; |
726 | |
727 | unlock: |
728 | spin_unlock_irq(&mapping->tree_lock); |
729 | return ret; |
730 | } |
731 | |
732 | /* |
733 | * Flush the mapping to the persistent domain within the byte range of [start, |
734 | * end]. This is required by data integrity operations to ensure file data is |
735 | * on persistent storage prior to completion of the operation. |
736 | */ |
737 | int dax_writeback_mapping_range(struct address_space *mapping, |
738 | struct block_device *bdev, struct writeback_control *wbc) |
739 | { |
740 | struct inode *inode = mapping->host; |
741 | pgoff_t start_index, end_index, pmd_index; |
742 | pgoff_t indices[PAGEVEC_SIZE]; |
743 | struct pagevec pvec; |
744 | bool done = false; |
745 | int i, ret = 0; |
746 | void *entry; |
747 | |
748 | if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) |
749 | return -EIO; |
750 | |
751 | if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) |
752 | return 0; |
753 | |
754 | start_index = wbc->range_start >> PAGE_SHIFT; |
755 | end_index = wbc->range_end >> PAGE_SHIFT; |
756 | pmd_index = DAX_PMD_INDEX(start_index); |
757 | |
758 | rcu_read_lock(); |
759 | entry = radix_tree_lookup(&mapping->page_tree, pmd_index); |
760 | rcu_read_unlock(); |
761 | |
762 | /* see if the start of our range is covered by a PMD entry */ |
763 | if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) |
764 | start_index = pmd_index; |
765 | |
766 | tag_pages_for_writeback(mapping, start_index, end_index); |
767 | |
768 | pagevec_init(&pvec, 0); |
769 | while (!done) { |
770 | pvec.nr = find_get_entries_tag(mapping, start_index, |
771 | PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE, |
772 | pvec.pages, indices); |
773 | |
774 | if (pvec.nr == 0) |
775 | break; |
776 | |
777 | for (i = 0; i < pvec.nr; i++) { |
778 | if (indices[i] > end_index) { |
779 | done = true; |
780 | break; |
781 | } |
782 | |
783 | ret = dax_writeback_one(bdev, mapping, indices[i], |
784 | pvec.pages[i]); |
785 | if (ret < 0) |
786 | return ret; |
787 | } |
788 | start_index = indices[pvec.nr - 1] + 1; |
789 | } |
790 | return 0; |
791 | } |
792 | EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); |
793 | |
794 | static int dax_insert_mapping(struct address_space *mapping, |
795 | struct block_device *bdev, sector_t sector, size_t size, |
796 | void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf) |
797 | { |
798 | unsigned long vaddr = (unsigned long)vmf->virtual_address; |
799 | struct blk_dax_ctl dax = { |
800 | .sector = sector, |
801 | .size = size, |
802 | }; |
803 | void *ret; |
804 | void *entry = *entryp; |
805 | |
806 | if (dax_map_atomic(bdev, &dax) < 0) |
807 | return PTR_ERR(dax.addr); |
808 | dax_unmap_atomic(bdev, &dax); |
809 | |
810 | ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector); |
811 | if (IS_ERR(ret)) |
812 | return PTR_ERR(ret); |
813 | *entryp = ret; |
814 | |
815 | return vm_insert_mixed(vma, vaddr, dax.pfn); |
816 | } |
817 | |
818 | /** |
819 | * dax_fault - handle a page fault on a DAX file |
820 | * @vma: The virtual memory area where the fault occurred |
821 | * @vmf: The description of the fault |
822 | * @get_block: The filesystem method used to translate file offsets to blocks |
823 | * |
824 | * When a page fault occurs, filesystems may call this helper in their |
825 | * fault handler for DAX files. dax_fault() assumes the caller has done all |
826 | * the necessary locking for the page fault to proceed successfully. |
827 | */ |
828 | int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, |
829 | get_block_t get_block) |
830 | { |
831 | struct file *file = vma->vm_file; |
832 | struct address_space *mapping = file->f_mapping; |
833 | struct inode *inode = mapping->host; |
834 | void *entry; |
835 | struct buffer_head bh; |
836 | unsigned long vaddr = (unsigned long)vmf->virtual_address; |
837 | unsigned blkbits = inode->i_blkbits; |
838 | sector_t block; |
839 | pgoff_t size; |
840 | int error; |
841 | int major = 0; |
842 | |
843 | /* |
844 | * Check whether offset isn't beyond end of file now. Caller is supposed |
845 | * to hold locks serializing us with truncate / punch hole so this is |
846 | * a reliable test. |
847 | */ |
848 | size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; |
849 | if (vmf->pgoff >= size) |
850 | return VM_FAULT_SIGBUS; |
851 | |
852 | memset(&bh, 0, sizeof(bh)); |
853 | block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits); |
854 | bh.b_bdev = inode->i_sb->s_bdev; |
855 | bh.b_size = PAGE_SIZE; |
856 | |
857 | entry = grab_mapping_entry(mapping, vmf->pgoff); |
858 | if (IS_ERR(entry)) { |
859 | error = PTR_ERR(entry); |
860 | goto out; |
861 | } |
862 | |
863 | error = get_block(inode, block, &bh, 0); |
864 | if (!error && (bh.b_size < PAGE_SIZE)) |
865 | error = -EIO; /* fs corruption? */ |
866 | if (error) |
867 | goto unlock_entry; |
868 | |
869 | if (vmf->cow_page) { |
870 | struct page *new_page = vmf->cow_page; |
871 | if (buffer_written(&bh)) |
872 | error = copy_user_dax(bh.b_bdev, to_sector(&bh, inode), |
873 | bh.b_size, new_page, vaddr); |
874 | else |
875 | clear_user_highpage(new_page, vaddr); |
876 | if (error) |
877 | goto unlock_entry; |
878 | if (!radix_tree_exceptional_entry(entry)) { |
879 | vmf->page = entry; |
880 | return VM_FAULT_LOCKED; |
881 | } |
882 | vmf->entry = entry; |
883 | return VM_FAULT_DAX_LOCKED; |
884 | } |
885 | |
886 | if (!buffer_mapped(&bh)) { |
887 | if (vmf->flags & FAULT_FLAG_WRITE) { |
888 | error = get_block(inode, block, &bh, 1); |
889 | count_vm_event(PGMAJFAULT); |
890 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
891 | major = VM_FAULT_MAJOR; |
892 | if (!error && (bh.b_size < PAGE_SIZE)) |
893 | error = -EIO; |
894 | if (error) |
895 | goto unlock_entry; |
896 | } else { |
897 | return dax_load_hole(mapping, entry, vmf); |
898 | } |
899 | } |
900 | |
901 | /* Filesystem should not return unwritten buffers to us! */ |
902 | WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); |
903 | error = dax_insert_mapping(mapping, bh.b_bdev, to_sector(&bh, inode), |
904 | bh.b_size, &entry, vma, vmf); |
905 | unlock_entry: |
906 | put_locked_mapping_entry(mapping, vmf->pgoff, entry); |
907 | out: |
908 | if (error == -ENOMEM) |
909 | return VM_FAULT_OOM | major; |
910 | /* -EBUSY is fine, somebody else faulted on the same PTE */ |
911 | if ((error < 0) && (error != -EBUSY)) |
912 | return VM_FAULT_SIGBUS | major; |
913 | return VM_FAULT_NOPAGE | major; |
914 | } |
915 | EXPORT_SYMBOL_GPL(dax_fault); |
916 | |
917 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) |
918 | /* |
919 | * The 'colour' (ie low bits) within a PMD of a page offset. This comes up |
920 | * more often than one might expect in the below function. |
921 | */ |
922 | #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) |
923 | |
924 | static void __dax_dbg(struct buffer_head *bh, unsigned long address, |
925 | const char *reason, const char *fn) |
926 | { |
927 | if (bh) { |
928 | char bname[BDEVNAME_SIZE]; |
929 | bdevname(bh->b_bdev, bname); |
930 | pr_debug("%s: %s addr: %lx dev %s state %lx start %lld " |
931 | "length %zd fallback: %s\n", fn, current->comm, |
932 | address, bname, bh->b_state, (u64)bh->b_blocknr, |
933 | bh->b_size, reason); |
934 | } else { |
935 | pr_debug("%s: %s addr: %lx fallback: %s\n", fn, |
936 | current->comm, address, reason); |
937 | } |
938 | } |
939 | |
940 | #define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd") |
941 | |
942 | /** |
943 | * dax_pmd_fault - handle a PMD fault on a DAX file |
944 | * @vma: The virtual memory area where the fault occurred |
945 | * @vmf: The description of the fault |
946 | * @get_block: The filesystem method used to translate file offsets to blocks |
947 | * |
948 | * When a page fault occurs, filesystems may call this helper in their |
949 | * pmd_fault handler for DAX files. |
950 | */ |
951 | int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, |
952 | pmd_t *pmd, unsigned int flags, get_block_t get_block) |
953 | { |
954 | struct file *file = vma->vm_file; |
955 | struct address_space *mapping = file->f_mapping; |
956 | struct inode *inode = mapping->host; |
957 | struct buffer_head bh; |
958 | unsigned blkbits = inode->i_blkbits; |
959 | unsigned long pmd_addr = address & PMD_MASK; |
960 | bool write = flags & FAULT_FLAG_WRITE; |
961 | struct block_device *bdev; |
962 | pgoff_t size, pgoff; |
963 | sector_t block; |
964 | int result = 0; |
965 | bool alloc = false; |
966 | |
967 | /* dax pmd mappings require pfn_t_devmap() */ |
968 | if (!IS_ENABLED(CONFIG_FS_DAX_PMD)) |
969 | return VM_FAULT_FALLBACK; |
970 | |
971 | /* Fall back to PTEs if we're going to COW */ |
972 | if (write && !(vma->vm_flags & VM_SHARED)) { |
973 | split_huge_pmd(vma, pmd, address); |
974 | dax_pmd_dbg(NULL, address, "cow write"); |
975 | return VM_FAULT_FALLBACK; |
976 | } |
977 | /* If the PMD would extend outside the VMA */ |
978 | if (pmd_addr < vma->vm_start) { |
979 | dax_pmd_dbg(NULL, address, "vma start unaligned"); |
980 | return VM_FAULT_FALLBACK; |
981 | } |
982 | if ((pmd_addr + PMD_SIZE) > vma->vm_end) { |
983 | dax_pmd_dbg(NULL, address, "vma end unaligned"); |
984 | return VM_FAULT_FALLBACK; |
985 | } |
986 | |
987 | pgoff = linear_page_index(vma, pmd_addr); |
988 | size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; |
989 | if (pgoff >= size) |
990 | return VM_FAULT_SIGBUS; |
991 | /* If the PMD would cover blocks out of the file */ |
992 | if ((pgoff | PG_PMD_COLOUR) >= size) { |
993 | dax_pmd_dbg(NULL, address, |
994 | "offset + huge page size > file size"); |
995 | return VM_FAULT_FALLBACK; |
996 | } |
997 | |
998 | memset(&bh, 0, sizeof(bh)); |
999 | bh.b_bdev = inode->i_sb->s_bdev; |
1000 | block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); |
1001 | |
1002 | bh.b_size = PMD_SIZE; |
1003 | |
1004 | if (get_block(inode, block, &bh, 0) != 0) |
1005 | return VM_FAULT_SIGBUS; |
1006 | |
1007 | if (!buffer_mapped(&bh) && write) { |
1008 | if (get_block(inode, block, &bh, 1) != 0) |
1009 | return VM_FAULT_SIGBUS; |
1010 | alloc = true; |
1011 | WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); |
1012 | } |
1013 | |
1014 | bdev = bh.b_bdev; |
1015 | |
1016 | /* |
1017 | * If the filesystem isn't willing to tell us the length of a hole, |
1018 | * just fall back to PTEs. Calling get_block 512 times in a loop |
1019 | * would be silly. |
1020 | */ |
1021 | if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) { |
1022 | dax_pmd_dbg(&bh, address, "allocated block too small"); |
1023 | return VM_FAULT_FALLBACK; |
1024 | } |
1025 | |
1026 | /* |
1027 | * If we allocated new storage, make sure no process has any |
1028 | * zero pages covering this hole |
1029 | */ |
1030 | if (alloc) { |
1031 | loff_t lstart = pgoff << PAGE_SHIFT; |
1032 | loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */ |
1033 | |
1034 | truncate_pagecache_range(inode, lstart, lend); |
1035 | } |
1036 | |
1037 | if (!write && !buffer_mapped(&bh)) { |
1038 | spinlock_t *ptl; |
1039 | pmd_t entry; |
1040 | struct page *zero_page = mm_get_huge_zero_page(vma->vm_mm); |
1041 | |
1042 | if (unlikely(!zero_page)) { |
1043 | dax_pmd_dbg(&bh, address, "no zero page"); |
1044 | goto fallback; |
1045 | } |
1046 | |
1047 | ptl = pmd_lock(vma->vm_mm, pmd); |
1048 | if (!pmd_none(*pmd)) { |
1049 | spin_unlock(ptl); |
1050 | dax_pmd_dbg(&bh, address, "pmd already present"); |
1051 | goto fallback; |
1052 | } |
1053 | |
1054 | dev_dbg(part_to_dev(bdev->bd_part), |
1055 | "%s: %s addr: %lx pfn: <zero> sect: %llx\n", |
1056 | __func__, current->comm, address, |
1057 | (unsigned long long) to_sector(&bh, inode)); |
1058 | |
1059 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
1060 | entry = pmd_mkhuge(entry); |
1061 | set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry); |
1062 | result = VM_FAULT_NOPAGE; |
1063 | spin_unlock(ptl); |
1064 | } else { |
1065 | struct blk_dax_ctl dax = { |
1066 | .sector = to_sector(&bh, inode), |
1067 | .size = PMD_SIZE, |
1068 | }; |
1069 | long length = dax_map_atomic(bdev, &dax); |
1070 | |
1071 | if (length < 0) { |
1072 | dax_pmd_dbg(&bh, address, "dax-error fallback"); |
1073 | goto fallback; |
1074 | } |
1075 | if (length < PMD_SIZE) { |
1076 | dax_pmd_dbg(&bh, address, "dax-length too small"); |
1077 | dax_unmap_atomic(bdev, &dax); |
1078 | goto fallback; |
1079 | } |
1080 | if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) { |
1081 | dax_pmd_dbg(&bh, address, "pfn unaligned"); |
1082 | dax_unmap_atomic(bdev, &dax); |
1083 | goto fallback; |
1084 | } |
1085 | |
1086 | if (!pfn_t_devmap(dax.pfn)) { |
1087 | dax_unmap_atomic(bdev, &dax); |
1088 | dax_pmd_dbg(&bh, address, "pfn not in memmap"); |
1089 | goto fallback; |
1090 | } |
1091 | dax_unmap_atomic(bdev, &dax); |
1092 | |
1093 | /* |
1094 | * For PTE faults we insert a radix tree entry for reads, and |
1095 | * leave it clean. Then on the first write we dirty the radix |
1096 | * tree entry via the dax_pfn_mkwrite() path. This sequence |
1097 | * allows the dax_pfn_mkwrite() call to be simpler and avoid a |
1098 | * call into get_block() to translate the pgoff to a sector in |
1099 | * order to be able to create a new radix tree entry. |
1100 | * |
1101 | * The PMD path doesn't have an equivalent to |
1102 | * dax_pfn_mkwrite(), though, so for a read followed by a |
1103 | * write we traverse all the way through dax_pmd_fault() |
1104 | * twice. This means we can just skip inserting a radix tree |
1105 | * entry completely on the initial read and just wait until |
1106 | * the write to insert a dirty entry. |
1107 | */ |
1108 | if (write) { |
1109 | /* |
1110 | * We should insert radix-tree entry and dirty it here. |
1111 | * For now this is broken... |
1112 | */ |
1113 | } |
1114 | |
1115 | dev_dbg(part_to_dev(bdev->bd_part), |
1116 | "%s: %s addr: %lx pfn: %lx sect: %llx\n", |
1117 | __func__, current->comm, address, |
1118 | pfn_t_to_pfn(dax.pfn), |
1119 | (unsigned long long) dax.sector); |
1120 | result |= vmf_insert_pfn_pmd(vma, address, pmd, |
1121 | dax.pfn, write); |
1122 | } |
1123 | |
1124 | out: |
1125 | return result; |
1126 | |
1127 | fallback: |
1128 | count_vm_event(THP_FAULT_FALLBACK); |
1129 | result = VM_FAULT_FALLBACK; |
1130 | goto out; |
1131 | } |
1132 | EXPORT_SYMBOL_GPL(dax_pmd_fault); |
1133 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
1134 | |
1135 | /** |
1136 | * dax_pfn_mkwrite - handle first write to DAX page |
1137 | * @vma: The virtual memory area where the fault occurred |
1138 | * @vmf: The description of the fault |
1139 | */ |
1140 | int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) |
1141 | { |
1142 | struct file *file = vma->vm_file; |
1143 | struct address_space *mapping = file->f_mapping; |
1144 | void *entry; |
1145 | pgoff_t index = vmf->pgoff; |
1146 | |
1147 | spin_lock_irq(&mapping->tree_lock); |
1148 | entry = get_unlocked_mapping_entry(mapping, index, NULL); |
1149 | if (!entry || !radix_tree_exceptional_entry(entry)) |
1150 | goto out; |
1151 | radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY); |
1152 | put_unlocked_mapping_entry(mapping, index, entry); |
1153 | out: |
1154 | spin_unlock_irq(&mapping->tree_lock); |
1155 | return VM_FAULT_NOPAGE; |
1156 | } |
1157 | EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); |
1158 | |
1159 | static bool dax_range_is_aligned(struct block_device *bdev, |
1160 | unsigned int offset, unsigned int length) |
1161 | { |
1162 | unsigned short sector_size = bdev_logical_block_size(bdev); |
1163 | |
1164 | if (!IS_ALIGNED(offset, sector_size)) |
1165 | return false; |
1166 | if (!IS_ALIGNED(length, sector_size)) |
1167 | return false; |
1168 | |
1169 | return true; |
1170 | } |
1171 | |
1172 | int __dax_zero_page_range(struct block_device *bdev, sector_t sector, |
1173 | unsigned int offset, unsigned int length) |
1174 | { |
1175 | struct blk_dax_ctl dax = { |
1176 | .sector = sector, |
1177 | .size = PAGE_SIZE, |
1178 | }; |
1179 | |
1180 | if (dax_range_is_aligned(bdev, offset, length)) { |
1181 | sector_t start_sector = dax.sector + (offset >> 9); |
1182 | |
1183 | return blkdev_issue_zeroout(bdev, start_sector, |
1184 | length >> 9, GFP_NOFS, true); |
1185 | } else { |
1186 | if (dax_map_atomic(bdev, &dax) < 0) |
1187 | return PTR_ERR(dax.addr); |
1188 | clear_pmem(dax.addr + offset, length); |
1189 | dax_unmap_atomic(bdev, &dax); |
1190 | } |
1191 | return 0; |
1192 | } |
1193 | EXPORT_SYMBOL_GPL(__dax_zero_page_range); |
1194 | |
1195 | /** |
1196 | * dax_zero_page_range - zero a range within a page of a DAX file |
1197 | * @inode: The file being truncated |
1198 | * @from: The file offset that is being truncated to |
1199 | * @length: The number of bytes to zero |
1200 | * @get_block: The filesystem method used to translate file offsets to blocks |
1201 | * |
1202 | * This function can be called by a filesystem when it is zeroing part of a |
1203 | * page in a DAX file. This is intended for hole-punch operations. If |
1204 | * you are truncating a file, the helper function dax_truncate_page() may be |
1205 | * more convenient. |
1206 | */ |
1207 | int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, |
1208 | get_block_t get_block) |
1209 | { |
1210 | struct buffer_head bh; |
1211 | pgoff_t index = from >> PAGE_SHIFT; |
1212 | unsigned offset = from & (PAGE_SIZE-1); |
1213 | int err; |
1214 | |
1215 | /* Block boundary? Nothing to do */ |
1216 | if (!length) |
1217 | return 0; |
1218 | BUG_ON((offset + length) > PAGE_SIZE); |
1219 | |
1220 | memset(&bh, 0, sizeof(bh)); |
1221 | bh.b_bdev = inode->i_sb->s_bdev; |
1222 | bh.b_size = PAGE_SIZE; |
1223 | err = get_block(inode, index, &bh, 0); |
1224 | if (err < 0 || !buffer_written(&bh)) |
1225 | return err; |
1226 | |
1227 | return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode), |
1228 | offset, length); |
1229 | } |
1230 | EXPORT_SYMBOL_GPL(dax_zero_page_range); |
1231 | |
1232 | /** |
1233 | * dax_truncate_page - handle a partial page being truncated in a DAX file |
1234 | * @inode: The file being truncated |
1235 | * @from: The file offset that is being truncated to |
1236 | * @get_block: The filesystem method used to translate file offsets to blocks |
1237 | * |
1238 | * Similar to block_truncate_page(), this function can be called by a |
1239 | * filesystem when it is truncating a DAX file to handle the partial page. |
1240 | */ |
1241 | int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) |
1242 | { |
1243 | unsigned length = PAGE_ALIGN(from) - from; |
1244 | return dax_zero_page_range(inode, from, length, get_block); |
1245 | } |
1246 | EXPORT_SYMBOL_GPL(dax_truncate_page); |
1247 | |
1248 | #ifdef CONFIG_FS_IOMAP |
1249 | static loff_t |
1250 | iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, |
1251 | struct iomap *iomap) |
1252 | { |
1253 | struct iov_iter *iter = data; |
1254 | loff_t end = pos + length, done = 0; |
1255 | ssize_t ret = 0; |
1256 | |
1257 | if (iov_iter_rw(iter) == READ) { |
1258 | end = min(end, i_size_read(inode)); |
1259 | if (pos >= end) |
1260 | return 0; |
1261 | |
1262 | if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) |
1263 | return iov_iter_zero(min(length, end - pos), iter); |
1264 | } |
1265 | |
1266 | if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED)) |
1267 | return -EIO; |
1268 | |
1269 | /* |
1270 | * Write can allocate block for an area which has a hole page mapped |
1271 | * into page tables. We have to tear down these mappings so that data |
1272 | * written by write(2) is visible in mmap. |
1273 | */ |
1274 | if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) { |
1275 | invalidate_inode_pages2_range(inode->i_mapping, |
1276 | pos >> PAGE_SHIFT, |
1277 | (end - 1) >> PAGE_SHIFT); |
1278 | } |
1279 | |
1280 | while (pos < end) { |
1281 | unsigned offset = pos & (PAGE_SIZE - 1); |
1282 | struct blk_dax_ctl dax = { 0 }; |
1283 | ssize_t map_len; |
1284 | |
1285 | if (fatal_signal_pending(current)) { |
1286 | ret = -EINTR; |
1287 | break; |
1288 | } |
1289 | |
1290 | dax.sector = iomap->blkno + |
1291 | (((pos & PAGE_MASK) - iomap->offset) >> 9); |
1292 | dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK; |
1293 | map_len = dax_map_atomic(iomap->bdev, &dax); |
1294 | if (map_len < 0) { |
1295 | ret = map_len; |
1296 | break; |
1297 | } |
1298 | |
1299 | dax.addr += offset; |
1300 | map_len -= offset; |
1301 | if (map_len > end - pos) |
1302 | map_len = end - pos; |
1303 | |
1304 | if (iov_iter_rw(iter) == WRITE) |
1305 | map_len = copy_from_iter_pmem(dax.addr, map_len, iter); |
1306 | else |
1307 | map_len = copy_to_iter(dax.addr, map_len, iter); |
1308 | dax_unmap_atomic(iomap->bdev, &dax); |
1309 | if (map_len <= 0) { |
1310 | ret = map_len ? map_len : -EFAULT; |
1311 | break; |
1312 | } |
1313 | |
1314 | pos += map_len; |
1315 | length -= map_len; |
1316 | done += map_len; |
1317 | } |
1318 | |
1319 | return done ? done : ret; |
1320 | } |
1321 | |
1322 | /** |
1323 | * iomap_dax_rw - Perform I/O to a DAX file |
1324 | * @iocb: The control block for this I/O |
1325 | * @iter: The addresses to do I/O from or to |
1326 | * @ops: iomap ops passed from the file system |
1327 | * |
1328 | * This function performs read and write operations to directly mapped |
1329 | * persistent memory. The callers needs to take care of read/write exclusion |
1330 | * and evicting any page cache pages in the region under I/O. |
1331 | */ |
1332 | ssize_t |
1333 | iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, |
1334 | struct iomap_ops *ops) |
1335 | { |
1336 | struct address_space *mapping = iocb->ki_filp->f_mapping; |
1337 | struct inode *inode = mapping->host; |
1338 | loff_t pos = iocb->ki_pos, ret = 0, done = 0; |
1339 | unsigned flags = 0; |
1340 | |
1341 | if (iov_iter_rw(iter) == WRITE) |
1342 | flags |= IOMAP_WRITE; |
1343 | |
1344 | while (iov_iter_count(iter)) { |
1345 | ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops, |
1346 | iter, iomap_dax_actor); |
1347 | if (ret <= 0) |
1348 | break; |
1349 | pos += ret; |
1350 | done += ret; |
1351 | } |
1352 | |
1353 | iocb->ki_pos += done; |
1354 | return done ? done : ret; |
1355 | } |
1356 | EXPORT_SYMBOL_GPL(iomap_dax_rw); |
1357 | |
1358 | /** |
1359 | * iomap_dax_fault - handle a page fault on a DAX file |
1360 | * @vma: The virtual memory area where the fault occurred |
1361 | * @vmf: The description of the fault |
1362 | * @ops: iomap ops passed from the file system |
1363 | * |
1364 | * When a page fault occurs, filesystems may call this helper in their fault |
1365 | * or mkwrite handler for DAX files. Assumes the caller has done all the |
1366 | * necessary locking for the page fault to proceed successfully. |
1367 | */ |
1368 | int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, |
1369 | struct iomap_ops *ops) |
1370 | { |
1371 | struct address_space *mapping = vma->vm_file->f_mapping; |
1372 | struct inode *inode = mapping->host; |
1373 | unsigned long vaddr = (unsigned long)vmf->virtual_address; |
1374 | loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; |
1375 | sector_t sector; |
1376 | struct iomap iomap = { 0 }; |
1377 | unsigned flags = 0; |
1378 | int error, major = 0; |
1379 | void *entry; |
1380 | |
1381 | /* |
1382 | * Check whether offset isn't beyond end of file now. Caller is supposed |
1383 | * to hold locks serializing us with truncate / punch hole so this is |
1384 | * a reliable test. |
1385 | */ |
1386 | if (pos >= i_size_read(inode)) |
1387 | return VM_FAULT_SIGBUS; |
1388 | |
1389 | entry = grab_mapping_entry(mapping, vmf->pgoff); |
1390 | if (IS_ERR(entry)) { |
1391 | error = PTR_ERR(entry); |
1392 | goto out; |
1393 | } |
1394 | |
1395 | if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) |
1396 | flags |= IOMAP_WRITE; |
1397 | |
1398 | /* |
1399 | * Note that we don't bother to use iomap_apply here: DAX required |
1400 | * the file system block size to be equal the page size, which means |
1401 | * that we never have to deal with more than a single extent here. |
1402 | */ |
1403 | error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap); |
1404 | if (error) |
1405 | goto unlock_entry; |
1406 | if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { |
1407 | error = -EIO; /* fs corruption? */ |
1408 | goto unlock_entry; |
1409 | } |
1410 | |
1411 | sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9); |
1412 | |
1413 | if (vmf->cow_page) { |
1414 | switch (iomap.type) { |
1415 | case IOMAP_HOLE: |
1416 | case IOMAP_UNWRITTEN: |
1417 | clear_user_highpage(vmf->cow_page, vaddr); |
1418 | break; |
1419 | case IOMAP_MAPPED: |
1420 | error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE, |
1421 | vmf->cow_page, vaddr); |
1422 | break; |
1423 | default: |
1424 | WARN_ON_ONCE(1); |
1425 | error = -EIO; |
1426 | break; |
1427 | } |
1428 | |
1429 | if (error) |
1430 | goto unlock_entry; |
1431 | if (!radix_tree_exceptional_entry(entry)) { |
1432 | vmf->page = entry; |
1433 | return VM_FAULT_LOCKED; |
1434 | } |
1435 | vmf->entry = entry; |
1436 | return VM_FAULT_DAX_LOCKED; |
1437 | } |
1438 | |
1439 | switch (iomap.type) { |
1440 | case IOMAP_MAPPED: |
1441 | if (iomap.flags & IOMAP_F_NEW) { |
1442 | count_vm_event(PGMAJFAULT); |
1443 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
1444 | major = VM_FAULT_MAJOR; |
1445 | } |
1446 | error = dax_insert_mapping(mapping, iomap.bdev, sector, |
1447 | PAGE_SIZE, &entry, vma, vmf); |
1448 | break; |
1449 | case IOMAP_UNWRITTEN: |
1450 | case IOMAP_HOLE: |
1451 | if (!(vmf->flags & FAULT_FLAG_WRITE)) |
1452 | return dax_load_hole(mapping, entry, vmf); |
1453 | /*FALLTHRU*/ |
1454 | default: |
1455 | WARN_ON_ONCE(1); |
1456 | error = -EIO; |
1457 | break; |
1458 | } |
1459 | |
1460 | unlock_entry: |
1461 | put_locked_mapping_entry(mapping, vmf->pgoff, entry); |
1462 | out: |
1463 | if (error == -ENOMEM) |
1464 | return VM_FAULT_OOM | major; |
1465 | /* -EBUSY is fine, somebody else faulted on the same PTE */ |
1466 | if (error < 0 && error != -EBUSY) |
1467 | return VM_FAULT_SIGBUS | major; |
1468 | return VM_FAULT_NOPAGE | major; |
1469 | } |
1470 | EXPORT_SYMBOL_GPL(iomap_dax_fault); |
1471 | #endif /* CONFIG_FS_IOMAP */ |
1472 |