1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * dax: direct host memory access
4 * Copyright (C) 2020 Red Hat, Inc.
5 */
6
7 #include "fuse_i.h"
8
9 #include <linux/delay.h>
10 #include <linux/dax.h>
11 #include <linux/uio.h>
12 #include <linux/pagemap.h>
13 #include <linux/pfn_t.h>
14 #include <linux/iomap.h>
15 #include <linux/interval_tree.h>
16
17 /*
18 * Default memory range size. A power of 2 so it agrees with common FUSE_INIT
19 * map_alignment values 4KB and 64KB.
20 */
21 #define FUSE_DAX_SHIFT 21
22 #define FUSE_DAX_SZ (1 << FUSE_DAX_SHIFT)
23 #define FUSE_DAX_PAGES (FUSE_DAX_SZ / PAGE_SIZE)
24
25 /* Number of ranges reclaimer will try to free in one invocation */
26 #define FUSE_DAX_RECLAIM_CHUNK (10)
27
28 /*
29 * Dax memory reclaim threshold in percetage of total ranges. When free
30 * number of free ranges drops below this threshold, reclaim can trigger
31 * Default is 20%
32 */
33 #define FUSE_DAX_RECLAIM_THRESHOLD (20)
34
35 /** Translation information for file offsets to DAX window offsets */
36 struct fuse_dax_mapping {
37 /* Pointer to inode where this memory range is mapped */
38 struct inode *inode;
39
40 /* Will connect in fcd->free_ranges to keep track of free memory */
41 struct list_head list;
42
43 /* For interval tree in file/inode */
44 struct interval_tree_node itn;
45
46 /* Will connect in fc->busy_ranges to keep track busy memory */
47 struct list_head busy_list;
48
49 /** Position in DAX window */
50 u64 window_offset;
51
52 /** Length of mapping, in bytes */
53 loff_t length;
54
55 /* Is this mapping read-only or read-write */
56 bool writable;
57
58 /* reference count when the mapping is used by dax iomap. */
59 refcount_t refcnt;
60 };
61
62 /* Per-inode dax map */
63 struct fuse_inode_dax {
64 /* Semaphore to protect modifications to the dmap tree */
65 struct rw_semaphore sem;
66
67 /* Sorted rb tree of struct fuse_dax_mapping elements */
68 struct rb_root_cached tree;
69 unsigned long nr;
70 };
71
72 struct fuse_conn_dax {
73 /* DAX device */
74 struct dax_device *dev;
75
76 /* Lock protecting accessess to members of this structure */
77 spinlock_t lock;
78
79 /* List of memory ranges which are busy */
80 unsigned long nr_busy_ranges;
81 struct list_head busy_ranges;
82
83 /* Worker to free up memory ranges */
84 struct delayed_work free_work;
85
86 /* Wait queue for a dax range to become free */
87 wait_queue_head_t range_waitq;
88
89 /* DAX Window Free Ranges */
90 long nr_free_ranges;
91 struct list_head free_ranges;
92
93 unsigned long nr_ranges;
94 };
95
96 static inline struct fuse_dax_mapping *
97 node_to_dmap(struct interval_tree_node *node)
98 {
99 if (!node)
100 return NULL;
101
102 return container_of(node, struct fuse_dax_mapping, itn);
103 }
104
105 static struct fuse_dax_mapping *
106 alloc_dax_mapping_reclaim(struct fuse_conn_dax *fcd, struct inode *inode);
107
108 static void
109 __kick_dmap_free_worker(struct fuse_conn_dax *fcd, unsigned long delay_ms)
110 {
111 unsigned long free_threshold;
112
113 /* If number of free ranges are below threshold, start reclaim */
114 free_threshold = max_t(unsigned long, fcd->nr_ranges * FUSE_DAX_RECLAIM_THRESHOLD / 100,
115 1);
116 if (fcd->nr_free_ranges < free_threshold)
117 queue_delayed_work(system_long_wq, &fcd->free_work,
118 msecs_to_jiffies(delay_ms));
119 }
120
121 static void kick_dmap_free_worker(struct fuse_conn_dax *fcd,
122 unsigned long delay_ms)
123 {
124 spin_lock(&fcd->lock);
125 __kick_dmap_free_worker(fcd, delay_ms);
126 spin_unlock(&fcd->lock);
127 }
128
129 static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn_dax *fcd)
130 {
131 struct fuse_dax_mapping *dmap;
132
133 spin_lock(&fcd->lock);
134 dmap = list_first_entry_or_null(&fcd->free_ranges,
135 struct fuse_dax_mapping, list);
136 if (dmap) {
137 list_del_init(&dmap->list);
138 WARN_ON(fcd->nr_free_ranges <= 0);
139 fcd->nr_free_ranges--;
140 }
141 __kick_dmap_free_worker(fcd, 0);
142 spin_unlock(&fcd->lock);
143
144 return dmap;
145 }
146
147 /* This assumes fcd->lock is held */
148 static void __dmap_remove_busy_list(struct fuse_conn_dax *fcd,
149 struct fuse_dax_mapping *dmap)
150 {
151 list_del_init(&dmap->busy_list);
152 WARN_ON(fcd->nr_busy_ranges == 0);
153 fcd->nr_busy_ranges--;
154 }
155
156 static void dmap_remove_busy_list(struct fuse_conn_dax *fcd,
157 struct fuse_dax_mapping *dmap)
158 {
159 spin_lock(&fcd->lock);
160 __dmap_remove_busy_list(fcd, dmap);
161 spin_unlock(&fcd->lock);
162 }
163
164 /* This assumes fcd->lock is held */
165 static void __dmap_add_to_free_pool(struct fuse_conn_dax *fcd,
166 struct fuse_dax_mapping *dmap)
167 {
168 list_add_tail(&dmap->list, &fcd->free_ranges);
169 fcd->nr_free_ranges++;
170 wake_up(&fcd->range_waitq);
171 }
172
173 static void dmap_add_to_free_pool(struct fuse_conn_dax *fcd,
174 struct fuse_dax_mapping *dmap)
175 {
176 /* Return fuse_dax_mapping to free list */
177 spin_lock(&fcd->lock);
178 __dmap_add_to_free_pool(fcd, dmap);
179 spin_unlock(&fcd->lock);
180 }
181
182 static int fuse_setup_one_mapping(struct inode *inode, unsigned long start_idx,
183 struct fuse_dax_mapping *dmap, bool writable,
184 bool upgrade)
185 {
186 struct fuse_mount *fm = get_fuse_mount(inode);
187 struct fuse_conn_dax *fcd = fm->fc->dax;
188 struct fuse_inode *fi = get_fuse_inode(inode);
189 struct fuse_setupmapping_in inarg;
190 loff_t offset = start_idx << FUSE_DAX_SHIFT;
191 FUSE_ARGS(args);
192 ssize_t err;
193
194 WARN_ON(fcd->nr_free_ranges < 0);
195
196 /* Ask fuse daemon to setup mapping */
197 memset(&inarg, 0, sizeof(inarg));
198 inarg.foffset = offset;
199 inarg.fh = -1;
200 inarg.moffset = dmap->window_offset;
201 inarg.len = FUSE_DAX_SZ;
202 inarg.flags |= FUSE_SETUPMAPPING_FLAG_READ;
203 if (writable)
204 inarg.flags |= FUSE_SETUPMAPPING_FLAG_WRITE;
205 args.opcode = FUSE_SETUPMAPPING;
206 args.nodeid = fi->nodeid;
207 args.in_numargs = 1;
208 args.in_args[0].size = sizeof(inarg);
209 args.in_args[0].value = &inarg;
210 err = fuse_simple_request(fm, &args);
211 if (err < 0)
212 return err;
213 dmap->writable = writable;
214 if (!upgrade) {
215 /*
216 * We don't take a reference on inode. inode is valid right now
217 * and when inode is going away, cleanup logic should first
218 * cleanup dmap entries.
219 */
220 dmap->inode = inode;
221 dmap->itn.start = dmap->itn.last = start_idx;
222 /* Protected by fi->dax->sem */
223 interval_tree_insert(&dmap->itn, &fi->dax->tree);
224 fi->dax->nr++;
225 spin_lock(&fcd->lock);
226 list_add_tail(&dmap->busy_list, &fcd->busy_ranges);
227 fcd->nr_busy_ranges++;
228 spin_unlock(&fcd->lock);
229 }
230 return 0;
231 }
232
233 static int fuse_send_removemapping(struct inode *inode,
234 struct fuse_removemapping_in *inargp,
235 struct fuse_removemapping_one *remove_one)
236 {
237 struct fuse_inode *fi = get_fuse_inode(inode);
238 struct fuse_mount *fm = get_fuse_mount(inode);
239 FUSE_ARGS(args);
240
241 args.opcode = FUSE_REMOVEMAPPING;
242 args.nodeid = fi->nodeid;
243 args.in_numargs = 2;
244 args.in_args[0].size = sizeof(*inargp);
245 args.in_args[0].value = inargp;
246 args.in_args[1].size = inargp->count * sizeof(*remove_one);
247 args.in_args[1].value = remove_one;
248 return fuse_simple_request(fm, &args);
249 }
250
251 static int dmap_removemapping_list(struct inode *inode, unsigned int num,
252 struct list_head *to_remove)
253 {
254 struct fuse_removemapping_one *remove_one, *ptr;
255 struct fuse_removemapping_in inarg;
256 struct fuse_dax_mapping *dmap;
257 int ret, i = 0, nr_alloc;
258
259 nr_alloc = min_t(unsigned int, num, FUSE_REMOVEMAPPING_MAX_ENTRY);
260 remove_one = kmalloc_array(nr_alloc, sizeof(*remove_one), GFP_NOFS);
261 if (!remove_one)
262 return -ENOMEM;
263
264 ptr = remove_one;
265 list_for_each_entry(dmap, to_remove, list) {
266 ptr->moffset = dmap->window_offset;
267 ptr->len = dmap->length;
268 ptr++;
269 i++;
270 num--;
271 if (i >= nr_alloc || num == 0) {
272 memset(&inarg, 0, sizeof(inarg));
273 inarg.count = i;
274 ret = fuse_send_removemapping(inode, &inarg,
275 remove_one);
276 if (ret)
277 goto out;
278 ptr = remove_one;
279 i = 0;
280 }
281 }
282 out:
283 kfree(remove_one);
284 return ret;
285 }
286
287 /*
288 * Cleanup dmap entry and add back to free list. This should be called with
289 * fcd->lock held.
290 */
291 static void dmap_reinit_add_to_free_pool(struct fuse_conn_dax *fcd,
292 struct fuse_dax_mapping *dmap)
293 {
294 pr_debug("fuse: freeing memory range start_idx=0x%lx end_idx=0x%lx window_offset=0x%llx length=0x%llx\n",
295 dmap->itn.start, dmap->itn.last, dmap->window_offset,
296 dmap->length);
297 __dmap_remove_busy_list(fcd, dmap);
298 dmap->inode = NULL;
299 dmap->itn.start = dmap->itn.last = 0;
300 __dmap_add_to_free_pool(fcd, dmap);
301 }
302
303 /*
304 * Free inode dmap entries whose range falls inside [start, end].
305 * Does not take any locks. At this point of time it should only be
306 * called from evict_inode() path where we know all dmap entries can be
307 * reclaimed.
308 */
309 static void inode_reclaim_dmap_range(struct fuse_conn_dax *fcd,
310 struct inode *inode,
311 loff_t start, loff_t end)
312 {
313 struct fuse_inode *fi = get_fuse_inode(inode);
314 struct fuse_dax_mapping *dmap, *n;
315 int err, num = 0;
316 LIST_HEAD(to_remove);
317 unsigned long start_idx = start >> FUSE_DAX_SHIFT;
318 unsigned long end_idx = end >> FUSE_DAX_SHIFT;
319 struct interval_tree_node *node;
320
321 while (1) {
322 node = interval_tree_iter_first(&fi->dax->tree, start_idx,
323 end_idx);
324 if (!node)
325 break;
326 dmap = node_to_dmap(node);
327 /* inode is going away. There should not be any users of dmap */
328 WARN_ON(refcount_read(&dmap->refcnt) > 1);
329 interval_tree_remove(&dmap->itn, &fi->dax->tree);
330 num++;
331 list_add(&dmap->list, &to_remove);
332 }
333
334 /* Nothing to remove */
335 if (list_empty(&to_remove))
336 return;
337
338 WARN_ON(fi->dax->nr < num);
339 fi->dax->nr -= num;
340 err = dmap_removemapping_list(inode, num, &to_remove);
341 if (err && err != -ENOTCONN) {
342 pr_warn("Failed to removemappings. start=0x%llx end=0x%llx\n",
343 start, end);
344 }
345 spin_lock(&fcd->lock);
346 list_for_each_entry_safe(dmap, n, &to_remove, list) {
347 list_del_init(&dmap->list);
348 dmap_reinit_add_to_free_pool(fcd, dmap);
349 }
350 spin_unlock(&fcd->lock);
351 }
352
353 static int dmap_removemapping_one(struct inode *inode,
354 struct fuse_dax_mapping *dmap)
355 {
356 struct fuse_removemapping_one forget_one;
357 struct fuse_removemapping_in inarg;
358
359 memset(&inarg, 0, sizeof(inarg));
360 inarg.count = 1;
361 memset(&forget_one, 0, sizeof(forget_one));
362 forget_one.moffset = dmap->window_offset;
363 forget_one.len = dmap->length;
364
365 return fuse_send_removemapping(inode, &inarg, &forget_one);
366 }
367
368 /*
369 * It is called from evict_inode() and by that time inode is going away. So
370 * this function does not take any locks like fi->dax->sem for traversing
371 * that fuse inode interval tree. If that lock is taken then lock validator
372 * complains of deadlock situation w.r.t fs_reclaim lock.
373 */
374 void fuse_dax_inode_cleanup(struct inode *inode)
375 {
376 struct fuse_conn *fc = get_fuse_conn(inode);
377 struct fuse_inode *fi = get_fuse_inode(inode);
378
379 /*
380 * fuse_evict_inode() has already called truncate_inode_pages_final()
381 * before we arrive here. So we should not have to worry about any
382 * pages/exception entries still associated with inode.
383 */
384 inode_reclaim_dmap_range(fc->dax, inode, 0, -1);
385 WARN_ON(fi->dax->nr);
386 }
387
388 static void fuse_fill_iomap_hole(struct iomap *iomap, loff_t length)
389 {
390 iomap->addr = IOMAP_NULL_ADDR;
391 iomap->length = length;
392 iomap->type = IOMAP_HOLE;
393 }
394
395 static void fuse_fill_iomap(struct inode *inode, loff_t pos, loff_t length,
396 struct iomap *iomap, struct fuse_dax_mapping *dmap,
397 unsigned int flags)
398 {
399 loff_t offset, len;
400 loff_t i_size = i_size_read(inode);
401
402 offset = pos - (dmap->itn.start << FUSE_DAX_SHIFT);
403 len = min(length, dmap->length - offset);
404
405 /* If length is beyond end of file, truncate further */
406 if (pos + len > i_size)
407 len = i_size - pos;
408
409 if (len > 0) {
410 iomap->addr = dmap->window_offset + offset;
411 iomap->length = len;
412 if (flags & IOMAP_FAULT)
413 iomap->length = ALIGN(len, PAGE_SIZE);
414 iomap->type = IOMAP_MAPPED;
415 /*
416 * increace refcnt so that reclaim code knows this dmap is in
417 * use. This assumes fi->dax->sem mutex is held either
418 * shared/exclusive.
419 */
420 refcount_inc(&dmap->refcnt);
421
422 /* iomap->private should be NULL */
423 WARN_ON_ONCE(iomap->private);
424 iomap->private = dmap;
425 } else {
426 /* Mapping beyond end of file is hole */
427 fuse_fill_iomap_hole(iomap, length);
428 }
429 }
430
431 static int fuse_setup_new_dax_mapping(struct inode *inode, loff_t pos,
432 loff_t length, unsigned int flags,
433 struct iomap *iomap)
434 {
435 struct fuse_inode *fi = get_fuse_inode(inode);
436 struct fuse_conn *fc = get_fuse_conn(inode);
437 struct fuse_conn_dax *fcd = fc->dax;
438 struct fuse_dax_mapping *dmap, *alloc_dmap = NULL;
439 int ret;
440 bool writable = flags & IOMAP_WRITE;
441 unsigned long start_idx = pos >> FUSE_DAX_SHIFT;
442 struct interval_tree_node *node;
443
444 /*
445 * Can't do inline reclaim in fault path. We call
446 * dax_layout_busy_page() before we free a range. And
447 * fuse_wait_dax_page() drops mapping->invalidate_lock and requires it.
448 * In fault path we enter with mapping->invalidate_lock held and can't
449 * drop it. Also in fault path we hold mapping->invalidate_lock shared
450 * and not exclusive, so that creates further issues with
451 * fuse_wait_dax_page(). Hence return -EAGAIN and fuse_dax_fault()
452 * will wait for a memory range to become free and retry.
453 */
454 if (flags & IOMAP_FAULT) {
455 alloc_dmap = alloc_dax_mapping(fcd);
456 if (!alloc_dmap)
457 return -EAGAIN;
458 } else {
459 alloc_dmap = alloc_dax_mapping_reclaim(fcd, inode);
460 if (IS_ERR(alloc_dmap))
461 return PTR_ERR(alloc_dmap);
462 }
463
464 /* If we are here, we should have memory allocated */
465 if (WARN_ON(!alloc_dmap))
466 return -EIO;
467
468 /*
469 * Take write lock so that only one caller can try to setup mapping
470 * and other waits.
471 */
472 down_write(&fi->dax->sem);
473 /*
474 * We dropped lock. Check again if somebody else setup
475 * mapping already.
476 */
477 node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
478 if (node) {
479 dmap = node_to_dmap(node);
480 fuse_fill_iomap(inode, pos, length, iomap, dmap, flags);
481 dmap_add_to_free_pool(fcd, alloc_dmap);
482 up_write(&fi->dax->sem);
483 return 0;
484 }
485
486 /* Setup one mapping */
487 ret = fuse_setup_one_mapping(inode, pos >> FUSE_DAX_SHIFT, alloc_dmap,
488 writable, false);
489 if (ret < 0) {
490 dmap_add_to_free_pool(fcd, alloc_dmap);
491 up_write(&fi->dax->sem);
492 return ret;
493 }
494 fuse_fill_iomap(inode, pos, length, iomap, alloc_dmap, flags);
495 up_write(&fi->dax->sem);
496 return 0;
497 }
498
499 static int fuse_upgrade_dax_mapping(struct inode *inode, loff_t pos,
500 loff_t length, unsigned int flags,
501 struct iomap *iomap)
502 {
503 struct fuse_inode *fi = get_fuse_inode(inode);
504 struct fuse_dax_mapping *dmap;
505 int ret;
506 unsigned long idx = pos >> FUSE_DAX_SHIFT;
507 struct interval_tree_node *node;
508
509 /*
510 * Take exclusive lock so that only one caller can try to setup
511 * mapping and others wait.
512 */
513 down_write(&fi->dax->sem);
514 node = interval_tree_iter_first(&fi->dax->tree, idx, idx);
515
516 /* We are holding either inode lock or invalidate_lock, and that should
517 * ensure that dmap can't be truncated. We are holding a reference
518 * on dmap and that should make sure it can't be reclaimed. So dmap
519 * should still be there in tree despite the fact we dropped and
520 * re-acquired the fi->dax->sem lock.
521 */
522 ret = -EIO;
523 if (WARN_ON(!node))
524 goto out_err;
525
526 dmap = node_to_dmap(node);
527
528 /* We took an extra reference on dmap to make sure its not reclaimd.
529 * Now we hold fi->dax->sem lock and that reference is not needed
530 * anymore. Drop it.
531 */
532 if (refcount_dec_and_test(&dmap->refcnt)) {
533 /* refcount should not hit 0. This object only goes
534 * away when fuse connection goes away
535 */
536 WARN_ON_ONCE(1);
537 }
538
539 /* Maybe another thread already upgraded mapping while we were not
540 * holding lock.
541 */
542 if (dmap->writable) {
543 ret = 0;
544 goto out_fill_iomap;
545 }
546
547 ret = fuse_setup_one_mapping(inode, pos >> FUSE_DAX_SHIFT, dmap, true,
548 true);
549 if (ret < 0)
550 goto out_err;
551 out_fill_iomap:
552 fuse_fill_iomap(inode, pos, length, iomap, dmap, flags);
553 out_err:
554 up_write(&fi->dax->sem);
555 return ret;
556 }
557
558 /* This is just for DAX and the mapping is ephemeral, do not use it for other
559 * purposes since there is no block device with a permanent mapping.
560 */
561 static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
562 unsigned int flags, struct iomap *iomap,
563 struct iomap *srcmap)
564 {
565 struct fuse_inode *fi = get_fuse_inode(inode);
566 struct fuse_conn *fc = get_fuse_conn(inode);
567 struct fuse_dax_mapping *dmap;
568 bool writable = flags & IOMAP_WRITE;
569 unsigned long start_idx = pos >> FUSE_DAX_SHIFT;
570 struct interval_tree_node *node;
571
572 /* We don't support FIEMAP */
573 if (WARN_ON(flags & IOMAP_REPORT))
574 return -EIO;
575
576 iomap->offset = pos;
577 iomap->flags = 0;
578 iomap->bdev = NULL;
579 iomap->dax_dev = fc->dax->dev;
580
581 /*
582 * Both read/write and mmap path can race here. So we need something
583 * to make sure if we are setting up mapping, then other path waits
584 *
585 * For now, use a semaphore for this. It probably needs to be
586 * optimized later.
587 */
588 down_read(&fi->dax->sem);
589 node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
590 if (node) {
591 dmap = node_to_dmap(node);
592 if (writable && !dmap->writable) {
593 /* Upgrade read-only mapping to read-write. This will
594 * require exclusive fi->dax->sem lock as we don't want
595 * two threads to be trying to this simultaneously
596 * for same dmap. So drop shared lock and acquire
597 * exclusive lock.
598 *
599 * Before dropping fi->dax->sem lock, take reference
600 * on dmap so that its not freed by range reclaim.
601 */
602 refcount_inc(&dmap->refcnt);
603 up_read(&fi->dax->sem);
604 pr_debug("%s: Upgrading mapping at offset 0x%llx length 0x%llx\n",
605 __func__, pos, length);
606 return fuse_upgrade_dax_mapping(inode, pos, length,
607 flags, iomap);
608 } else {
609 fuse_fill_iomap(inode, pos, length, iomap, dmap, flags);
610 up_read(&fi->dax->sem);
611 return 0;
612 }
613 } else {
614 up_read(&fi->dax->sem);
615 pr_debug("%s: no mapping at offset 0x%llx length 0x%llx\n",
616 __func__, pos, length);
617 if (pos >= i_size_read(inode))
618 goto iomap_hole;
619
620 return fuse_setup_new_dax_mapping(inode, pos, length, flags,
621 iomap);
622 }
623
624 /*
625 * If read beyond end of file happens, fs code seems to return
626 * it as hole
627 */
628 iomap_hole:
629 fuse_fill_iomap_hole(iomap, length);
630 pr_debug("%s returning hole mapping. pos=0x%llx length_asked=0x%llx length_returned=0x%llx\n",
631 __func__, pos, length, iomap->length);
632 return 0;
633 }
634
635 static int fuse_iomap_end(struct inode *inode, loff_t pos, loff_t length,
636 ssize_t written, unsigned int flags,
637 struct iomap *iomap)
638 {
639 struct fuse_dax_mapping *dmap = iomap->private;
640
641 if (dmap) {
642 if (refcount_dec_and_test(&dmap->refcnt)) {
643 /* refcount should not hit 0. This object only goes
644 * away when fuse connection goes away
645 */
646 WARN_ON_ONCE(1);
647 }
648 }
649
650 /* DAX writes beyond end-of-file aren't handled using iomap, so the
651 * file size is unchanged and there is nothing to do here.
652 */
653 return 0;
654 }
655
656 static const struct iomap_ops fuse_iomap_ops = {
657 .iomap_begin = fuse_iomap_begin,
658 .iomap_end = fuse_iomap_end,
659 };
660
661 static void fuse_wait_dax_page(struct inode *inode)
662 {
663 filemap_invalidate_unlock(inode->i_mapping);
664 schedule();
665 filemap_invalidate_lock(inode->i_mapping);
666 }
667
668 /* Should be called with mapping->invalidate_lock held exclusively */
669 static int __fuse_dax_break_layouts(struct inode *inode, bool *retry,
670 loff_t start, loff_t end)
671 {
672 struct page *page;
673
674 page = dax_layout_busy_page_range(inode->i_mapping, start, end);
675 if (!page)
676 return 0;
677
678 *retry = true;
679 return ___wait_var_event(&page->_refcount,
680 atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
681 0, 0, fuse_wait_dax_page(inode));
682 }
683
684 /* dmap_end == 0 leads to unmapping of whole file */
685 int fuse_dax_break_layouts(struct inode *inode, u64 dmap_start,
686 u64 dmap_end)
687 {
688 bool retry;
689 int ret;
690
691 do {
692 retry = false;
693 ret = __fuse_dax_break_layouts(inode, &retry, dmap_start,
694 dmap_end);
695 } while (ret == 0 && retry);
696
697 return ret;
698 }
699
700 ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
701 {
702 struct inode *inode = file_inode(iocb->ki_filp);
703 ssize_t ret;
704
705 if (iocb->ki_flags & IOCB_NOWAIT) {
706 if (!inode_trylock_shared(inode))
707 return -EAGAIN;
708 } else {
709 inode_lock_shared(inode);
710 }
711
712 ret = dax_iomap_rw(iocb, to, &fuse_iomap_ops);
713 inode_unlock_shared(inode);
714
715 /* TODO file_accessed(iocb->f_filp) */
716 return ret;
717 }
718
719 static bool file_extending_write(struct kiocb *iocb, struct iov_iter *from)
720 {
721 struct inode *inode = file_inode(iocb->ki_filp);
722
723 return (iov_iter_rw(from) == WRITE &&
724 ((iocb->ki_pos) >= i_size_read(inode) ||
725 (iocb->ki_pos + iov_iter_count(from) > i_size_read(inode))));
726 }
727
728 static ssize_t fuse_dax_direct_write(struct kiocb *iocb, struct iov_iter *from)
729 {
730 struct inode *inode = file_inode(iocb->ki_filp);
731 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
732 ssize_t ret;
733
734 ret = fuse_direct_io(&io, from, &iocb->ki_pos, FUSE_DIO_WRITE);
735
736 fuse_write_update_attr(inode, iocb->ki_pos, ret);
737 return ret;
738 }
739
740 ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
741 {
742 struct inode *inode = file_inode(iocb->ki_filp);
743 ssize_t ret;
744
745 if (iocb->ki_flags & IOCB_NOWAIT) {
746 if (!inode_trylock(inode))
747 return -EAGAIN;
748 } else {
749 inode_lock(inode);
750 }
751
752 ret = generic_write_checks(iocb, from);
753 if (ret <= 0)
754 goto out;
755
756 ret = file_remove_privs(iocb->ki_filp);
757 if (ret)
758 goto out;
759 /* TODO file_update_time() but we don't want metadata I/O */
760
761 /* Do not use dax for file extending writes as write and on
762 * disk i_size increase are not atomic otherwise.
763 */
764 if (file_extending_write(iocb, from))
765 ret = fuse_dax_direct_write(iocb, from);
766 else
767 ret = dax_iomap_rw(iocb, from, &fuse_iomap_ops);
768
769 out:
770 inode_unlock(inode);
771
772 if (ret > 0)
773 ret = generic_write_sync(iocb, ret);
774 return ret;
775 }
776
777 static int fuse_dax_writepages(struct address_space *mapping,
778 struct writeback_control *wbc)
779 {
780
781 struct inode *inode = mapping->host;
782 struct fuse_conn *fc = get_fuse_conn(inode);
783
784 return dax_writeback_mapping_range(mapping, fc->dax->dev, wbc);
785 }
786
787 static vm_fault_t __fuse_dax_fault(struct vm_fault *vmf, unsigned int order,
788 bool write)
789 {
790 vm_fault_t ret;
791 struct inode *inode = file_inode(vmf->vma->vm_file);
792 struct super_block *sb = inode->i_sb;
793 pfn_t pfn;
794 int error = 0;
795 struct fuse_conn *fc = get_fuse_conn(inode);
796 struct fuse_conn_dax *fcd = fc->dax;
797 bool retry = false;
798
799 if (write)
800 sb_start_pagefault(sb);
801 retry:
802 if (retry && !(fcd->nr_free_ranges > 0))
803 wait_event(fcd->range_waitq, (fcd->nr_free_ranges > 0));
804
805 /*
806 * We need to serialize against not only truncate but also against
807 * fuse dax memory range reclaim. While a range is being reclaimed,
808 * we do not want any read/write/mmap to make progress and try
809 * to populate page cache or access memory we are trying to free.
810 */
811 filemap_invalidate_lock_shared(inode->i_mapping);
812 ret = dax_iomap_fault(vmf, order, &pfn, &error, &fuse_iomap_ops);
813 if ((ret & VM_FAULT_ERROR) && error == -EAGAIN) {
814 error = 0;
815 retry = true;
816 filemap_invalidate_unlock_shared(inode->i_mapping);
817 goto retry;
818 }
819
820 if (ret & VM_FAULT_NEEDDSYNC)
821 ret = dax_finish_sync_fault(vmf, order, pfn);
822 filemap_invalidate_unlock_shared(inode->i_mapping);
823
824 if (write)
825 sb_end_pagefault(sb);
826
827 return ret;
828 }
829
830 static vm_fault_t fuse_dax_fault(struct vm_fault *vmf)
831 {
832 return __fuse_dax_fault(vmf, 0, vmf->flags & FAULT_FLAG_WRITE);
833 }
834
835 static vm_fault_t fuse_dax_huge_fault(struct vm_fault *vmf, unsigned int order)
836 {
837 return __fuse_dax_fault(vmf, order, vmf->flags & FAULT_FLAG_WRITE);
838 }
839
840 static vm_fault_t fuse_dax_page_mkwrite(struct vm_fault *vmf)
841 {
842 return __fuse_dax_fault(vmf, 0, true);
843 }
844
845 static vm_fault_t fuse_dax_pfn_mkwrite(struct vm_fault *vmf)
846 {
847 return __fuse_dax_fault(vmf, 0, true);
848 }
849
850 static const struct vm_operations_struct fuse_dax_vm_ops = {
851 .fault = fuse_dax_fault,
852 .huge_fault = fuse_dax_huge_fault,
853 .page_mkwrite = fuse_dax_page_mkwrite,
854 .pfn_mkwrite = fuse_dax_pfn_mkwrite,
855 };
856
857 int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma)
858 {
859 file_accessed(file);
860 vma->vm_ops = &fuse_dax_vm_ops;
861 vm_flags_set(vma, VM_MIXEDMAP | VM_HUGEPAGE);
862 return 0;
863 }
864
865 static int dmap_writeback_invalidate(struct inode *inode,
866 struct fuse_dax_mapping *dmap)
867 {
868 int ret;
869 loff_t start_pos = dmap->itn.start << FUSE_DAX_SHIFT;
870 loff_t end_pos = (start_pos + FUSE_DAX_SZ - 1);
871
872 ret = filemap_fdatawrite_range(inode->i_mapping, start_pos, end_pos);
873 if (ret) {
874 pr_debug("fuse: filemap_fdatawrite_range() failed. err=%d start_pos=0x%llx, end_pos=0x%llx\n",
875 ret, start_pos, end_pos);
876 return ret;
877 }
878
879 ret = invalidate_inode_pages2_range(inode->i_mapping,
880 start_pos >> PAGE_SHIFT,
881 end_pos >> PAGE_SHIFT);
882 if (ret)
883 pr_debug("fuse: invalidate_inode_pages2_range() failed err=%d\n",
884 ret);
885
886 return ret;
887 }
888
889 static int reclaim_one_dmap_locked(struct inode *inode,
890 struct fuse_dax_mapping *dmap)
891 {
892 int ret;
893 struct fuse_inode *fi = get_fuse_inode(inode);
894
895 /*
896 * igrab() was done to make sure inode won't go under us, and this
897 * further avoids the race with evict().
898 */
899 ret = dmap_writeback_invalidate(inode, dmap);
900 if (ret)
901 return ret;
902
903 /* Remove dax mapping from inode interval tree now */
904 interval_tree_remove(&dmap->itn, &fi->dax->tree);
905 fi->dax->nr--;
906
907 /* It is possible that umount/shutdown has killed the fuse connection
908 * and worker thread is trying to reclaim memory in parallel. Don't
909 * warn in that case.
910 */
911 ret = dmap_removemapping_one(inode, dmap);
912 if (ret && ret != -ENOTCONN) {
913 pr_warn("Failed to remove mapping. offset=0x%llx len=0x%llx ret=%d\n",
914 dmap->window_offset, dmap->length, ret);
915 }
916 return 0;
917 }
918
919 /* Find first mapped dmap for an inode and return file offset. Caller needs
920 * to hold fi->dax->sem lock either shared or exclusive.
921 */
922 static struct fuse_dax_mapping *inode_lookup_first_dmap(struct inode *inode)
923 {
924 struct fuse_inode *fi = get_fuse_inode(inode);
925 struct fuse_dax_mapping *dmap;
926 struct interval_tree_node *node;
927
928 for (node = interval_tree_iter_first(&fi->dax->tree, 0, -1); node;
929 node = interval_tree_iter_next(node, 0, -1)) {
930 dmap = node_to_dmap(node);
931 /* still in use. */
932 if (refcount_read(&dmap->refcnt) > 1)
933 continue;
934
935 return dmap;
936 }
937
938 return NULL;
939 }
940
941 /*
942 * Find first mapping in the tree and free it and return it. Do not add
943 * it back to free pool.
944 */
945 static struct fuse_dax_mapping *
946 inode_inline_reclaim_one_dmap(struct fuse_conn_dax *fcd, struct inode *inode,
947 bool *retry)
948 {
949 struct fuse_inode *fi = get_fuse_inode(inode);
950 struct fuse_dax_mapping *dmap;
951 u64 dmap_start, dmap_end;
952 unsigned long start_idx;
953 int ret;
954 struct interval_tree_node *node;
955
956 filemap_invalidate_lock(inode->i_mapping);
957
958 /* Lookup a dmap and corresponding file offset to reclaim. */
959 down_read(&fi->dax->sem);
960 dmap = inode_lookup_first_dmap(inode);
961 if (dmap) {
962 start_idx = dmap->itn.start;
963 dmap_start = start_idx << FUSE_DAX_SHIFT;
964 dmap_end = dmap_start + FUSE_DAX_SZ - 1;
965 }
966 up_read(&fi->dax->sem);
967
968 if (!dmap)
969 goto out_mmap_sem;
970 /*
971 * Make sure there are no references to inode pages using
972 * get_user_pages()
973 */
974 ret = fuse_dax_break_layouts(inode, dmap_start, dmap_end);
975 if (ret) {
976 pr_debug("fuse: fuse_dax_break_layouts() failed. err=%d\n",
977 ret);
978 dmap = ERR_PTR(ret);
979 goto out_mmap_sem;
980 }
981
982 down_write(&fi->dax->sem);
983 node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
984 /* Range already got reclaimed by somebody else */
985 if (!node) {
986 if (retry)
987 *retry = true;
988 goto out_write_dmap_sem;
989 }
990
991 dmap = node_to_dmap(node);
992 /* still in use. */
993 if (refcount_read(&dmap->refcnt) > 1) {
994 dmap = NULL;
995 if (retry)
996 *retry = true;
997 goto out_write_dmap_sem;
998 }
999
1000 ret = reclaim_one_dmap_locked(inode, dmap);
1001 if (ret < 0) {
1002 dmap = ERR_PTR(ret);
1003 goto out_write_dmap_sem;
1004 }
1005
1006 /* Clean up dmap. Do not add back to free list */
1007 dmap_remove_busy_list(fcd, dmap);
1008 dmap->inode = NULL;
1009 dmap->itn.start = dmap->itn.last = 0;
1010
1011 pr_debug("fuse: %s: inline reclaimed memory range. inode=%p, window_offset=0x%llx, length=0x%llx\n",
1012 __func__, inode, dmap->window_offset, dmap->length);
1013
1014 out_write_dmap_sem:
1015 up_write(&fi->dax->sem);
1016 out_mmap_sem:
1017 filemap_invalidate_unlock(inode->i_mapping);
1018 return dmap;
1019 }
1020
1021 static struct fuse_dax_mapping *
1022 alloc_dax_mapping_reclaim(struct fuse_conn_dax *fcd, struct inode *inode)
1023 {
1024 struct fuse_dax_mapping *dmap;
1025 struct fuse_inode *fi = get_fuse_inode(inode);
1026
1027 while (1) {
1028 bool retry = false;
1029
1030 dmap = alloc_dax_mapping(fcd);
1031 if (dmap)
1032 return dmap;
1033
1034 dmap = inode_inline_reclaim_one_dmap(fcd, inode, &retry);
1035 /*
1036 * Either we got a mapping or it is an error, return in both
1037 * the cases.
1038 */
1039 if (dmap)
1040 return dmap;
1041
1042 /* If we could not reclaim a mapping because it
1043 * had a reference or some other temporary failure,
1044 * Try again. We want to give up inline reclaim only
1045 * if there is no range assigned to this node. Otherwise
1046 * if a deadlock is possible if we sleep with
1047 * mapping->invalidate_lock held and worker to free memory
1048 * can't make progress due to unavailability of
1049 * mapping->invalidate_lock. So sleep only if fi->dax->nr=0
1050 */
1051 if (retry)
1052 continue;
1053 /*
1054 * There are no mappings which can be reclaimed. Wait for one.
1055 * We are not holding fi->dax->sem. So it is possible
1056 * that range gets added now. But as we are not holding
1057 * mapping->invalidate_lock, worker should still be able to
1058 * free up a range and wake us up.
1059 */
1060 if (!fi->dax->nr && !(fcd->nr_free_ranges > 0)) {
1061 if (wait_event_killable_exclusive(fcd->range_waitq,
1062 (fcd->nr_free_ranges > 0))) {
1063 return ERR_PTR(-EINTR);
1064 }
1065 }
1066 }
1067 }
1068
1069 static int lookup_and_reclaim_dmap_locked(struct fuse_conn_dax *fcd,
1070 struct inode *inode,
1071 unsigned long start_idx)
1072 {
1073 int ret;
1074 struct fuse_inode *fi = get_fuse_inode(inode);
1075 struct fuse_dax_mapping *dmap;
1076 struct interval_tree_node *node;
1077
1078 /* Find fuse dax mapping at file offset inode. */
1079 node = interval_tree_iter_first(&fi->dax->tree, start_idx, start_idx);
1080
1081 /* Range already got cleaned up by somebody else */
1082 if (!node)
1083 return 0;
1084 dmap = node_to_dmap(node);
1085
1086 /* still in use. */
1087 if (refcount_read(&dmap->refcnt) > 1)
1088 return 0;
1089
1090 ret = reclaim_one_dmap_locked(inode, dmap);
1091 if (ret < 0)
1092 return ret;
1093
1094 /* Cleanup dmap entry and add back to free list */
1095 spin_lock(&fcd->lock);
1096 dmap_reinit_add_to_free_pool(fcd, dmap);
1097 spin_unlock(&fcd->lock);
1098 return ret;
1099 }
1100
1101 /*
1102 * Free a range of memory.
1103 * Locking:
1104 * 1. Take mapping->invalidate_lock to block dax faults.
1105 * 2. Take fi->dax->sem to protect interval tree and also to make sure
1106 * read/write can not reuse a dmap which we might be freeing.
1107 */
1108 static int lookup_and_reclaim_dmap(struct fuse_conn_dax *fcd,
1109 struct inode *inode,
1110 unsigned long start_idx,
1111 unsigned long end_idx)
1112 {
1113 int ret;
1114 struct fuse_inode *fi = get_fuse_inode(inode);
1115 loff_t dmap_start = start_idx << FUSE_DAX_SHIFT;
1116 loff_t dmap_end = (dmap_start + FUSE_DAX_SZ) - 1;
1117
1118 filemap_invalidate_lock(inode->i_mapping);
1119 ret = fuse_dax_break_layouts(inode, dmap_start, dmap_end);
1120 if (ret) {
1121 pr_debug("virtio_fs: fuse_dax_break_layouts() failed. err=%d\n",
1122 ret);
1123 goto out_mmap_sem;
1124 }
1125
1126 down_write(&fi->dax->sem);
1127 ret = lookup_and_reclaim_dmap_locked(fcd, inode, start_idx);
1128 up_write(&fi->dax->sem);
1129 out_mmap_sem:
1130 filemap_invalidate_unlock(inode->i_mapping);
1131 return ret;
1132 }
1133
1134 static int try_to_free_dmap_chunks(struct fuse_conn_dax *fcd,
1135 unsigned long nr_to_free)
1136 {
1137 struct fuse_dax_mapping *dmap, *pos, *temp;
1138 int ret, nr_freed = 0;
1139 unsigned long start_idx = 0, end_idx = 0;
1140 struct inode *inode = NULL;
1141
1142 /* Pick first busy range and free it for now*/
1143 while (1) {
1144 if (nr_freed >= nr_to_free)
1145 break;
1146
1147 dmap = NULL;
1148 spin_lock(&fcd->lock);
1149
1150 if (!fcd->nr_busy_ranges) {
1151 spin_unlock(&fcd->lock);
1152 return 0;
1153 }
1154
1155 list_for_each_entry_safe(pos, temp, &fcd->busy_ranges,
1156 busy_list) {
1157 /* skip this range if it's in use. */
1158 if (refcount_read(&pos->refcnt) > 1)
1159 continue;
1160
1161 inode = igrab(pos->inode);
1162 /*
1163 * This inode is going away. That will free
1164 * up all the ranges anyway, continue to
1165 * next range.
1166 */
1167 if (!inode)
1168 continue;
1169 /*
1170 * Take this element off list and add it tail. If
1171 * this element can't be freed, it will help with
1172 * selecting new element in next iteration of loop.
1173 */
1174 dmap = pos;
1175 list_move_tail(&dmap->busy_list, &fcd->busy_ranges);
1176 start_idx = end_idx = dmap->itn.start;
1177 break;
1178 }
1179 spin_unlock(&fcd->lock);
1180 if (!dmap)
1181 return 0;
1182
1183 ret = lookup_and_reclaim_dmap(fcd, inode, start_idx, end_idx);
1184 iput(inode);
1185 if (ret)
1186 return ret;
1187 nr_freed++;
1188 }
1189 return 0;
1190 }
1191
1192 static void fuse_dax_free_mem_worker(struct work_struct *work)
1193 {
1194 int ret;
1195 struct fuse_conn_dax *fcd = container_of(work, struct fuse_conn_dax,
1196 free_work.work);
1197 ret = try_to_free_dmap_chunks(fcd, FUSE_DAX_RECLAIM_CHUNK);
1198 if (ret) {
1199 pr_debug("fuse: try_to_free_dmap_chunks() failed with err=%d\n",
1200 ret);
1201 }
1202
1203 /* If number of free ranges are still below threshold, requeue */
1204 kick_dmap_free_worker(fcd, 1);
1205 }
1206
1207 static void fuse_free_dax_mem_ranges(struct list_head *mem_list)
1208 {
1209 struct fuse_dax_mapping *range, *temp;
1210
1211 /* Free All allocated elements */
1212 list_for_each_entry_safe(range, temp, mem_list, list) {
1213 list_del(&range->list);
1214 if (!list_empty(&range->busy_list))
1215 list_del(&range->busy_list);
1216 kfree(range);
1217 }
1218 }
1219
1220 void fuse_dax_conn_free(struct fuse_conn *fc)
1221 {
1222 if (fc->dax) {
1223 fuse_free_dax_mem_ranges(&fc->dax->free_ranges);
1224 kfree(fc->dax);
1225 fc->dax = NULL;
1226 }
1227 }
1228
1229 static int fuse_dax_mem_range_init(struct fuse_conn_dax *fcd)
1230 {
1231 long nr_pages, nr_ranges;
1232 struct fuse_dax_mapping *range;
1233 int ret, id;
1234 size_t dax_size = -1;
1235 unsigned long i;
1236
1237 init_waitqueue_head(&fcd->range_waitq);
1238 INIT_LIST_HEAD(&fcd->free_ranges);
1239 INIT_LIST_HEAD(&fcd->busy_ranges);
1240 INIT_DELAYED_WORK(&fcd->free_work, fuse_dax_free_mem_worker);
1241
1242 id = dax_read_lock();
1243 nr_pages = dax_direct_access(fcd->dev, 0, PHYS_PFN(dax_size),
1244 DAX_ACCESS, NULL, NULL);
1245 dax_read_unlock(id);
1246 if (nr_pages < 0) {
1247 pr_debug("dax_direct_access() returned %ld\n", nr_pages);
1248 return nr_pages;
1249 }
1250
1251 nr_ranges = nr_pages/FUSE_DAX_PAGES;
1252 pr_debug("%s: dax mapped %ld pages. nr_ranges=%ld\n",
1253 __func__, nr_pages, nr_ranges);
1254
1255 for (i = 0; i < nr_ranges; i++) {
1256 range = kzalloc(sizeof(struct fuse_dax_mapping), GFP_KERNEL);
1257 ret = -ENOMEM;
1258 if (!range)
1259 goto out_err;
1260
1261 /* TODO: This offset only works if virtio-fs driver is not
1262 * having some memory hidden at the beginning. This needs
1263 * better handling
1264 */
1265 range->window_offset = i * FUSE_DAX_SZ;
1266 range->length = FUSE_DAX_SZ;
1267 INIT_LIST_HEAD(&range->busy_list);
1268 refcount_set(&range->refcnt, 1);
1269 list_add_tail(&range->list, &fcd->free_ranges);
1270 }
1271
1272 fcd->nr_free_ranges = nr_ranges;
1273 fcd->nr_ranges = nr_ranges;
1274 return 0;
1275 out_err:
1276 /* Free All allocated elements */
1277 fuse_free_dax_mem_ranges(&fcd->free_ranges);
1278 return ret;
1279 }
1280
1281 int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode dax_mode,
1282 struct dax_device *dax_dev)
1283 {
1284 struct fuse_conn_dax *fcd;
1285 int err;
1286
1287 fc->dax_mode = dax_mode;
1288
1289 if (!dax_dev)
1290 return 0;
1291
1292 fcd = kzalloc(sizeof(*fcd), GFP_KERNEL);
1293 if (!fcd)
1294 return -ENOMEM;
1295
1296 spin_lock_init(&fcd->lock);
1297 fcd->dev = dax_dev;
1298 err = fuse_dax_mem_range_init(fcd);
1299 if (err) {
1300 kfree(fcd);
1301 return err;
1302 }
1303
1304 fc->dax = fcd;
1305 return 0;
1306 }
1307
1308 bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi)
1309 {
1310 struct fuse_conn *fc = get_fuse_conn_super(sb);
1311
1312 fi->dax = NULL;
1313 if (fc->dax) {
1314 fi->dax = kzalloc(sizeof(*fi->dax), GFP_KERNEL_ACCOUNT);
1315 if (!fi->dax)
1316 return false;
1317
1318 init_rwsem(&fi->dax->sem);
1319 fi->dax->tree = RB_ROOT_CACHED;
1320 }
1321
1322 return true;
1323 }
1324
1325 static const struct address_space_operations fuse_dax_file_aops = {
1326 .writepages = fuse_dax_writepages,
1327 .direct_IO = noop_direct_IO,
1328 .dirty_folio = noop_dirty_folio,
1329 };
1330
1331 static bool fuse_should_enable_dax(struct inode *inode, unsigned int flags)
1332 {
1333 struct fuse_conn *fc = get_fuse_conn(inode);
1334 enum fuse_dax_mode dax_mode = fc->dax_mode;
1335
1336 if (dax_mode == FUSE_DAX_NEVER)
1337 return false;
1338
1339 /*
1340 * fc->dax may be NULL in 'inode' mode when filesystem device doesn't
1341 * support DAX, in which case it will silently fallback to 'never' mode.
1342 */
1343 if (!fc->dax)
1344 return false;
1345
1346 if (dax_mode == FUSE_DAX_ALWAYS)
1347 return true;
1348
1349 /* dax_mode is FUSE_DAX_INODE* */
1350 return fc->inode_dax && (flags & FUSE_ATTR_DAX);
1351 }
1352
1353 void fuse_dax_inode_init(struct inode *inode, unsigned int flags)
1354 {
1355 if (!fuse_should_enable_dax(inode, flags))
1356 return;
1357
1358 inode->i_flags |= S_DAX;
1359 inode->i_data.a_ops = &fuse_dax_file_aops;
1360 }
1361
1362 void fuse_dax_dontcache(struct inode *inode, unsigned int flags)
1363 {
1364 struct fuse_conn *fc = get_fuse_conn(inode);
1365
1366 if (fuse_is_inode_dax_mode(fc->dax_mode) &&
1367 ((bool) IS_DAX(inode) != (bool) (flags & FUSE_ATTR_DAX)))
1368 d_mark_dontcache(inode);
1369 }
1370
1371 bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment)
1372 {
1373 if (fc->dax && (map_alignment > FUSE_DAX_SHIFT)) {
1374 pr_warn("FUSE: map_alignment %u incompatible with dax mem range size %u\n",
1375 map_alignment, FUSE_DAX_SZ);
1376 return false;
1377 }
1378 return true;
1379 }
1380
1381 void fuse_dax_cancel_work(struct fuse_conn *fc)
1382 {
1383 struct fuse_conn_dax *fcd = fc->dax;
1384
1385 if (fcd)
1386 cancel_delayed_work_sync(&fcd->free_work);
1387
1388 }
1389 EXPORT_SYMBOL_GPL(fuse_dax_cancel_work);
1390
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