blob: c2ebf10b70daf706fcf80a1ad2cab3468fe75170 [file] [log] [blame]
Matthew Wilcoxd475c632015-02-16 15:58:56 -08001/*
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>
Ross Zwislerd77e92e2015-09-09 10:29:40 -060020#include <linux/dax.h>
Matthew Wilcoxd475c632015-02-16 15:58:56 -080021#include <linux/fs.h>
22#include <linux/genhd.h>
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -080023#include <linux/highmem.h>
24#include <linux/memcontrol.h>
25#include <linux/mm.h>
Matthew Wilcoxd475c632015-02-16 15:58:56 -080026#include <linux/mutex.h>
Ross Zwisler9973c982016-01-22 15:10:47 -080027#include <linux/pagevec.h>
Matthew Wilcox289c6ae2015-02-16 15:58:59 -080028#include <linux/sched.h>
Ingo Molnarf361bf42017-02-03 23:47:37 +010029#include <linux/sched/signal.h>
Matthew Wilcoxd475c632015-02-16 15:58:56 -080030#include <linux/uio.h>
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -080031#include <linux/vmstat.h>
Dan Williams34c0fd52016-01-15 16:56:14 -080032#include <linux/pfn_t.h>
Dan Williams0e749e52016-01-15 16:55:53 -080033#include <linux/sizes.h>
Jan Kara4b4bb462016-12-14 15:07:53 -080034#include <linux/mmu_notifier.h>
Christoph Hellwiga254e562016-09-19 11:24:49 +100035#include <linux/iomap.h>
36#include "internal.h"
Matthew Wilcoxd475c632015-02-16 15:58:56 -080037
Ross Zwisler282a8e02017-02-22 15:39:50 -080038#define CREATE_TRACE_POINTS
39#include <trace/events/fs_dax.h>
40
Jan Karaac401cc2016-05-12 18:29:18 +020041/* We choose 4096 entries - same as per-zone page wait tables */
42#define DAX_WAIT_TABLE_BITS 12
43#define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
44
Ross Zwisler917f3452017-09-06 16:18:58 -070045/* The 'colour' (ie low bits) within a PMD of a page offset. */
46#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
47
Ross Zwislerce95ab02016-11-08 11:31:44 +110048static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
Jan Karaac401cc2016-05-12 18:29:18 +020049
50static int __init init_dax_wait_table(void)
51{
52 int i;
53
54 for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++)
55 init_waitqueue_head(wait_table + i);
56 return 0;
57}
58fs_initcall(init_dax_wait_table);
59
Ross Zwisler527b19d2017-09-06 16:18:51 -070060/*
61 * We use lowest available bit in exceptional entry for locking, one bit for
62 * the entry size (PMD) and two more to tell us if the entry is a zero page or
63 * an empty entry that is just used for locking. In total four special bits.
64 *
65 * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE
66 * and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
67 * block allocation.
68 */
69#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
70#define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
71#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
72#define RADIX_DAX_ZERO_PAGE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
73#define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
74
75static unsigned long dax_radix_sector(void *entry)
76{
77 return (unsigned long)entry >> RADIX_DAX_SHIFT;
78}
79
80static void *dax_radix_locked_entry(sector_t sector, unsigned long flags)
81{
82 return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
83 ((unsigned long)sector << RADIX_DAX_SHIFT) |
84 RADIX_DAX_ENTRY_LOCK);
85}
86
87static unsigned int dax_radix_order(void *entry)
88{
89 if ((unsigned long)entry & RADIX_DAX_PMD)
90 return PMD_SHIFT - PAGE_SHIFT;
91 return 0;
92}
93
Ross Zwisler642261a2016-11-08 11:34:45 +110094static int dax_is_pmd_entry(void *entry)
95{
96 return (unsigned long)entry & RADIX_DAX_PMD;
97}
98
99static int dax_is_pte_entry(void *entry)
100{
101 return !((unsigned long)entry & RADIX_DAX_PMD);
102}
103
104static int dax_is_zero_entry(void *entry)
105{
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700106 return (unsigned long)entry & RADIX_DAX_ZERO_PAGE;
Ross Zwisler642261a2016-11-08 11:34:45 +1100107}
108
109static int dax_is_empty_entry(void *entry)
110{
111 return (unsigned long)entry & RADIX_DAX_EMPTY;
112}
113
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800114/*
Jan Karaac401cc2016-05-12 18:29:18 +0200115 * DAX radix tree locking
116 */
117struct exceptional_entry_key {
118 struct address_space *mapping;
Ross Zwisler63e95b52016-11-08 11:32:20 +1100119 pgoff_t entry_start;
Jan Karaac401cc2016-05-12 18:29:18 +0200120};
121
122struct wait_exceptional_entry_queue {
Ingo Molnarac6424b2017-06-20 12:06:13 +0200123 wait_queue_entry_t wait;
Jan Karaac401cc2016-05-12 18:29:18 +0200124 struct exceptional_entry_key key;
125};
126
Ross Zwisler63e95b52016-11-08 11:32:20 +1100127static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
128 pgoff_t index, void *entry, struct exceptional_entry_key *key)
129{
130 unsigned long hash;
131
132 /*
133 * If 'entry' is a PMD, align the 'index' that we use for the wait
134 * queue to the start of that PMD. This ensures that all offsets in
135 * the range covered by the PMD map to the same bit lock.
136 */
Ross Zwisler642261a2016-11-08 11:34:45 +1100137 if (dax_is_pmd_entry(entry))
Ross Zwisler917f3452017-09-06 16:18:58 -0700138 index &= ~PG_PMD_COLOUR;
Ross Zwisler63e95b52016-11-08 11:32:20 +1100139
140 key->mapping = mapping;
141 key->entry_start = index;
142
143 hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS);
144 return wait_table + hash;
145}
146
Ingo Molnarac6424b2017-06-20 12:06:13 +0200147static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mode,
Jan Karaac401cc2016-05-12 18:29:18 +0200148 int sync, void *keyp)
149{
150 struct exceptional_entry_key *key = keyp;
151 struct wait_exceptional_entry_queue *ewait =
152 container_of(wait, struct wait_exceptional_entry_queue, wait);
153
154 if (key->mapping != ewait->key.mapping ||
Ross Zwisler63e95b52016-11-08 11:32:20 +1100155 key->entry_start != ewait->key.entry_start)
Jan Karaac401cc2016-05-12 18:29:18 +0200156 return 0;
157 return autoremove_wake_function(wait, mode, sync, NULL);
158}
159
160/*
Ross Zwislere30331f2017-09-06 16:18:39 -0700161 * We do not necessarily hold the mapping->tree_lock when we call this
162 * function so it is possible that 'entry' is no longer a valid item in the
163 * radix tree. This is okay because all we really need to do is to find the
164 * correct waitqueue where tasks might be waiting for that old 'entry' and
165 * wake them.
166 */
Ross Zwislerd01ad192017-09-06 16:18:47 -0700167static void dax_wake_mapping_entry_waiter(struct address_space *mapping,
Ross Zwislere30331f2017-09-06 16:18:39 -0700168 pgoff_t index, void *entry, bool wake_all)
169{
170 struct exceptional_entry_key key;
171 wait_queue_head_t *wq;
172
173 wq = dax_entry_waitqueue(mapping, index, entry, &key);
174
175 /*
176 * Checking for locked entry and prepare_to_wait_exclusive() happens
177 * under mapping->tree_lock, ditto for entry handling in our callers.
178 * So at this point all tasks that could have seen our entry locked
179 * must be in the waitqueue and the following check will see them.
180 */
181 if (waitqueue_active(wq))
182 __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
183}
184
185/*
Jan Karaac401cc2016-05-12 18:29:18 +0200186 * Check whether the given slot is locked. The function must be called with
187 * mapping->tree_lock held
188 */
189static inline int slot_locked(struct address_space *mapping, void **slot)
190{
191 unsigned long entry = (unsigned long)
192 radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
193 return entry & RADIX_DAX_ENTRY_LOCK;
194}
195
196/*
197 * Mark the given slot is locked. The function must be called with
198 * mapping->tree_lock held
199 */
200static inline void *lock_slot(struct address_space *mapping, void **slot)
201{
202 unsigned long entry = (unsigned long)
203 radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
204
205 entry |= RADIX_DAX_ENTRY_LOCK;
Johannes Weiner6d75f362016-12-12 16:43:43 -0800206 radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200207 return (void *)entry;
208}
209
210/*
211 * Mark the given slot is unlocked. The function must be called with
212 * mapping->tree_lock held
213 */
214static inline void *unlock_slot(struct address_space *mapping, void **slot)
215{
216 unsigned long entry = (unsigned long)
217 radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
218
219 entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
Johannes Weiner6d75f362016-12-12 16:43:43 -0800220 radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200221 return (void *)entry;
222}
223
224/*
225 * Lookup entry in radix tree, wait for it to become unlocked if it is
226 * exceptional entry and return it. The caller must call
227 * put_unlocked_mapping_entry() when he decided not to lock the entry or
228 * put_locked_mapping_entry() when he locked the entry and now wants to
229 * unlock it.
230 *
231 * The function must be called with mapping->tree_lock held.
232 */
233static void *get_unlocked_mapping_entry(struct address_space *mapping,
234 pgoff_t index, void ***slotp)
235{
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100236 void *entry, **slot;
Jan Karaac401cc2016-05-12 18:29:18 +0200237 struct wait_exceptional_entry_queue ewait;
Ross Zwisler63e95b52016-11-08 11:32:20 +1100238 wait_queue_head_t *wq;
Jan Karaac401cc2016-05-12 18:29:18 +0200239
240 init_wait(&ewait.wait);
241 ewait.wait.func = wake_exceptional_entry_func;
Jan Karaac401cc2016-05-12 18:29:18 +0200242
243 for (;;) {
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100244 entry = __radix_tree_lookup(&mapping->page_tree, index, NULL,
Jan Karaac401cc2016-05-12 18:29:18 +0200245 &slot);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700246 if (!entry ||
247 WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) ||
Jan Karaac401cc2016-05-12 18:29:18 +0200248 !slot_locked(mapping, slot)) {
249 if (slotp)
250 *slotp = slot;
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100251 return entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200252 }
Ross Zwisler63e95b52016-11-08 11:32:20 +1100253
254 wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
Jan Karaac401cc2016-05-12 18:29:18 +0200255 prepare_to_wait_exclusive(wq, &ewait.wait,
256 TASK_UNINTERRUPTIBLE);
257 spin_unlock_irq(&mapping->tree_lock);
258 schedule();
259 finish_wait(wq, &ewait.wait);
260 spin_lock_irq(&mapping->tree_lock);
261 }
262}
263
Jan Karab1aa8122016-12-14 15:07:24 -0800264static void dax_unlock_mapping_entry(struct address_space *mapping,
265 pgoff_t index)
266{
267 void *entry, **slot;
268
269 spin_lock_irq(&mapping->tree_lock);
270 entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
271 if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
272 !slot_locked(mapping, slot))) {
273 spin_unlock_irq(&mapping->tree_lock);
274 return;
275 }
276 unlock_slot(mapping, slot);
277 spin_unlock_irq(&mapping->tree_lock);
278 dax_wake_mapping_entry_waiter(mapping, index, entry, false);
279}
280
Jan Karaac401cc2016-05-12 18:29:18 +0200281static void put_locked_mapping_entry(struct address_space *mapping,
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700282 pgoff_t index)
Jan Karaac401cc2016-05-12 18:29:18 +0200283{
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700284 dax_unlock_mapping_entry(mapping, index);
Jan Karaac401cc2016-05-12 18:29:18 +0200285}
286
287/*
288 * Called when we are done with radix tree entry we looked up via
289 * get_unlocked_mapping_entry() and which we didn't lock in the end.
290 */
291static void put_unlocked_mapping_entry(struct address_space *mapping,
292 pgoff_t index, void *entry)
293{
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700294 if (!entry)
Jan Karaac401cc2016-05-12 18:29:18 +0200295 return;
296
297 /* We have to wake up next waiter for the radix tree entry lock */
Ross Zwisler422476c2016-11-08 11:33:44 +1100298 dax_wake_mapping_entry_waiter(mapping, index, entry, false);
299}
300
Jan Karaac401cc2016-05-12 18:29:18 +0200301/*
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700302 * Find radix tree entry at given index. If it points to an exceptional entry,
303 * return it with the radix tree entry locked. If the radix tree doesn't
304 * contain given index, create an empty exceptional entry for the index and
305 * return with it locked.
Jan Karaac401cc2016-05-12 18:29:18 +0200306 *
Ross Zwisler642261a2016-11-08 11:34:45 +1100307 * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
308 * either return that locked entry or will return an error. This error will
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700309 * happen if there are any 4k entries within the 2MiB range that we are
310 * requesting.
Ross Zwisler642261a2016-11-08 11:34:45 +1100311 *
312 * We always favor 4k entries over 2MiB entries. There isn't a flow where we
313 * evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB
314 * insertion will fail if it finds any 4k entries already in the tree, and a
315 * 4k insertion will cause an existing 2MiB entry to be unmapped and
316 * downgraded to 4k entries. This happens for both 2MiB huge zero pages as
317 * well as 2MiB empty entries.
318 *
319 * The exception to this downgrade path is for 2MiB DAX PMD entries that have
320 * real storage backing them. We will leave these real 2MiB DAX entries in
321 * the tree, and PTE writes will simply dirty the entire 2MiB DAX entry.
322 *
Jan Karaac401cc2016-05-12 18:29:18 +0200323 * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For
324 * persistent memory the benefit is doubtful. We can add that later if we can
325 * show it helps.
326 */
Ross Zwisler642261a2016-11-08 11:34:45 +1100327static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
328 unsigned long size_flag)
Jan Karaac401cc2016-05-12 18:29:18 +0200329{
Ross Zwisler642261a2016-11-08 11:34:45 +1100330 bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100331 void *entry, **slot;
Jan Karaac401cc2016-05-12 18:29:18 +0200332
333restart:
334 spin_lock_irq(&mapping->tree_lock);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100335 entry = get_unlocked_mapping_entry(mapping, index, &slot);
Ross Zwisler642261a2016-11-08 11:34:45 +1100336
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700337 if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) {
338 entry = ERR_PTR(-EIO);
339 goto out_unlock;
340 }
341
Ross Zwisler642261a2016-11-08 11:34:45 +1100342 if (entry) {
343 if (size_flag & RADIX_DAX_PMD) {
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700344 if (dax_is_pte_entry(entry)) {
Ross Zwisler642261a2016-11-08 11:34:45 +1100345 put_unlocked_mapping_entry(mapping, index,
346 entry);
347 entry = ERR_PTR(-EEXIST);
348 goto out_unlock;
349 }
350 } else { /* trying to grab a PTE entry */
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700351 if (dax_is_pmd_entry(entry) &&
Ross Zwisler642261a2016-11-08 11:34:45 +1100352 (dax_is_zero_entry(entry) ||
353 dax_is_empty_entry(entry))) {
354 pmd_downgrade = true;
355 }
356 }
357 }
358
Jan Karaac401cc2016-05-12 18:29:18 +0200359 /* No entry for given index? Make sure radix tree is big enough. */
Ross Zwisler642261a2016-11-08 11:34:45 +1100360 if (!entry || pmd_downgrade) {
Jan Karaac401cc2016-05-12 18:29:18 +0200361 int err;
362
Ross Zwisler642261a2016-11-08 11:34:45 +1100363 if (pmd_downgrade) {
364 /*
365 * Make sure 'entry' remains valid while we drop
366 * mapping->tree_lock.
367 */
368 entry = lock_slot(mapping, slot);
369 }
370
Jan Karaac401cc2016-05-12 18:29:18 +0200371 spin_unlock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100372 /*
373 * Besides huge zero pages the only other thing that gets
374 * downgraded are empty entries which don't need to be
375 * unmapped.
376 */
377 if (pmd_downgrade && dax_is_zero_entry(entry))
378 unmap_mapping_range(mapping,
379 (index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
380
Jan Kara0cb80b42016-12-12 21:34:12 -0500381 err = radix_tree_preload(
382 mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
383 if (err) {
384 if (pmd_downgrade)
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700385 put_locked_mapping_entry(mapping, index);
Jan Kara0cb80b42016-12-12 21:34:12 -0500386 return ERR_PTR(err);
387 }
Jan Karaac401cc2016-05-12 18:29:18 +0200388 spin_lock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100389
Ross Zwislere11f8b72017-04-07 16:04:57 -0700390 if (!entry) {
391 /*
392 * We needed to drop the page_tree lock while calling
393 * radix_tree_preload() and we didn't have an entry to
394 * lock. See if another thread inserted an entry at
395 * our index during this time.
396 */
397 entry = __radix_tree_lookup(&mapping->page_tree, index,
398 NULL, &slot);
399 if (entry) {
400 radix_tree_preload_end();
401 spin_unlock_irq(&mapping->tree_lock);
402 goto restart;
403 }
404 }
405
Ross Zwisler642261a2016-11-08 11:34:45 +1100406 if (pmd_downgrade) {
407 radix_tree_delete(&mapping->page_tree, index);
408 mapping->nrexceptional--;
409 dax_wake_mapping_entry_waiter(mapping, index, entry,
410 true);
411 }
412
413 entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
414
415 err = __radix_tree_insert(&mapping->page_tree, index,
416 dax_radix_order(entry), entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200417 radix_tree_preload_end();
418 if (err) {
419 spin_unlock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100420 /*
Ross Zwislere11f8b72017-04-07 16:04:57 -0700421 * Our insertion of a DAX entry failed, most likely
422 * because we were inserting a PMD entry and it
423 * collided with a PTE sized entry at a different
424 * index in the PMD range. We haven't inserted
425 * anything into the radix tree and have no waiters to
426 * wake.
Ross Zwisler642261a2016-11-08 11:34:45 +1100427 */
Jan Karaac401cc2016-05-12 18:29:18 +0200428 return ERR_PTR(err);
429 }
430 /* Good, we have inserted empty locked entry into the tree. */
431 mapping->nrexceptional++;
432 spin_unlock_irq(&mapping->tree_lock);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100433 return entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200434 }
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100435 entry = lock_slot(mapping, slot);
Ross Zwisler642261a2016-11-08 11:34:45 +1100436 out_unlock:
Jan Karaac401cc2016-05-12 18:29:18 +0200437 spin_unlock_irq(&mapping->tree_lock);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100438 return entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200439}
440
Jan Karac6dcf522016-08-10 17:22:44 +0200441static int __dax_invalidate_mapping_entry(struct address_space *mapping,
442 pgoff_t index, bool trunc)
443{
444 int ret = 0;
445 void *entry;
446 struct radix_tree_root *page_tree = &mapping->page_tree;
447
448 spin_lock_irq(&mapping->tree_lock);
449 entry = get_unlocked_mapping_entry(mapping, index, NULL);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700450 if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)))
Jan Karac6dcf522016-08-10 17:22:44 +0200451 goto out;
452 if (!trunc &&
453 (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
454 radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)))
455 goto out;
456 radix_tree_delete(page_tree, index);
457 mapping->nrexceptional--;
458 ret = 1;
459out:
460 put_unlocked_mapping_entry(mapping, index, entry);
461 spin_unlock_irq(&mapping->tree_lock);
462 return ret;
463}
Jan Karaac401cc2016-05-12 18:29:18 +0200464/*
465 * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
466 * entry to get unlocked before deleting it.
467 */
468int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
469{
Jan Karac6dcf522016-08-10 17:22:44 +0200470 int ret = __dax_invalidate_mapping_entry(mapping, index, true);
Jan Karaac401cc2016-05-12 18:29:18 +0200471
Jan Karaac401cc2016-05-12 18:29:18 +0200472 /*
473 * This gets called from truncate / punch_hole path. As such, the caller
474 * must hold locks protecting against concurrent modifications of the
475 * radix tree (usually fs-private i_mmap_sem for writing). Since the
476 * caller has seen exceptional entry for this index, we better find it
477 * at that index as well...
478 */
Jan Karac6dcf522016-08-10 17:22:44 +0200479 WARN_ON_ONCE(!ret);
480 return ret;
481}
Jan Karaac401cc2016-05-12 18:29:18 +0200482
Jan Karac6dcf522016-08-10 17:22:44 +0200483/*
Jan Karac6dcf522016-08-10 17:22:44 +0200484 * Invalidate exceptional DAX entry if it is clean.
485 */
486int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
487 pgoff_t index)
488{
489 return __dax_invalidate_mapping_entry(mapping, index, false);
Jan Karaac401cc2016-05-12 18:29:18 +0200490}
491
Dan Williamscccbce62017-01-27 13:31:42 -0800492static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
493 sector_t sector, size_t size, struct page *to,
494 unsigned long vaddr)
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800495{
Dan Williamscccbce62017-01-27 13:31:42 -0800496 void *vto, *kaddr;
497 pgoff_t pgoff;
498 pfn_t pfn;
499 long rc;
500 int id;
Ross Zwislere2e05392015-08-18 13:55:41 -0600501
Dan Williamscccbce62017-01-27 13:31:42 -0800502 rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
503 if (rc)
504 return rc;
505
506 id = dax_read_lock();
507 rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
508 if (rc < 0) {
509 dax_read_unlock(id);
510 return rc;
511 }
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800512 vto = kmap_atomic(to);
Dan Williamscccbce62017-01-27 13:31:42 -0800513 copy_user_page(vto, (void __force *)kaddr, vaddr, to);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800514 kunmap_atomic(vto);
Dan Williamscccbce62017-01-27 13:31:42 -0800515 dax_read_unlock(id);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800516 return 0;
517}
518
Ross Zwisler642261a2016-11-08 11:34:45 +1100519/*
520 * By this point grab_mapping_entry() has ensured that we have a locked entry
521 * of the appropriate size so we don't have to worry about downgrading PMDs to
522 * PTEs. If we happen to be trying to insert a PTE and there is a PMD
523 * already in the tree, we will skip the insertion and just dirty the PMD as
524 * appropriate.
525 */
Jan Karaac401cc2016-05-12 18:29:18 +0200526static void *dax_insert_mapping_entry(struct address_space *mapping,
527 struct vm_fault *vmf,
Ross Zwisler642261a2016-11-08 11:34:45 +1100528 void *entry, sector_t sector,
Jan Karaf5b7b742017-11-01 16:36:40 +0100529 unsigned long flags, bool dirty)
Ross Zwisler9973c982016-01-22 15:10:47 -0800530{
531 struct radix_tree_root *page_tree = &mapping->page_tree;
Jan Karaac401cc2016-05-12 18:29:18 +0200532 void *new_entry;
533 pgoff_t index = vmf->pgoff;
Ross Zwisler9973c982016-01-22 15:10:47 -0800534
Jan Karaf5b7b742017-11-01 16:36:40 +0100535 if (dirty)
Dmitry Monakhovd2b2a282016-02-05 15:36:55 -0800536 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Ross Zwisler9973c982016-01-22 15:10:47 -0800537
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700538 if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_ZERO_PAGE)) {
539 /* we are replacing a zero page with block mapping */
540 if (dax_is_pmd_entry(entry))
541 unmap_mapping_range(mapping,
542 (vmf->pgoff << PAGE_SHIFT) & PMD_MASK,
543 PMD_SIZE, 0);
544 else /* pte entry */
545 unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
546 PAGE_SIZE, 0);
Ross Zwisler9973c982016-01-22 15:10:47 -0800547 }
548
Jan Karaac401cc2016-05-12 18:29:18 +0200549 spin_lock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100550 new_entry = dax_radix_locked_entry(sector, flags);
551
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700552 if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
Ross Zwisler642261a2016-11-08 11:34:45 +1100553 /*
554 * Only swap our new entry into the radix tree if the current
555 * entry is a zero page or an empty entry. If a normal PTE or
556 * PMD entry is already in the tree, we leave it alone. This
557 * means that if we are trying to insert a PTE and the
558 * existing entry is a PMD, we will just leave the PMD in the
559 * tree and dirty it if necessary.
560 */
Johannes Weinerf7942432016-12-12 16:43:41 -0800561 struct radix_tree_node *node;
Jan Karaac401cc2016-05-12 18:29:18 +0200562 void **slot;
563 void *ret;
Ross Zwisler9973c982016-01-22 15:10:47 -0800564
Johannes Weinerf7942432016-12-12 16:43:41 -0800565 ret = __radix_tree_lookup(page_tree, index, &node, &slot);
Jan Karaac401cc2016-05-12 18:29:18 +0200566 WARN_ON_ONCE(ret != entry);
Johannes Weiner4d693d02016-12-12 16:43:49 -0800567 __radix_tree_replace(page_tree, node, slot,
Mel Gormanc7df8ad2017-11-15 17:37:41 -0800568 new_entry, NULL);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700569 entry = new_entry;
Ross Zwisler9973c982016-01-22 15:10:47 -0800570 }
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700571
Jan Karaf5b7b742017-11-01 16:36:40 +0100572 if (dirty)
Ross Zwisler9973c982016-01-22 15:10:47 -0800573 radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700574
Ross Zwisler9973c982016-01-22 15:10:47 -0800575 spin_unlock_irq(&mapping->tree_lock);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700576 return entry;
Ross Zwisler9973c982016-01-22 15:10:47 -0800577}
578
Jan Kara4b4bb462016-12-14 15:07:53 -0800579static inline unsigned long
580pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
581{
582 unsigned long address;
583
584 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
585 VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
586 return address;
587}
588
589/* Walk all mappings of a given index of a file and writeprotect them */
590static void dax_mapping_entry_mkclean(struct address_space *mapping,
591 pgoff_t index, unsigned long pfn)
592{
593 struct vm_area_struct *vma;
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800594 pte_t pte, *ptep = NULL;
595 pmd_t *pmdp = NULL;
Jan Kara4b4bb462016-12-14 15:07:53 -0800596 spinlock_t *ptl;
Jan Kara4b4bb462016-12-14 15:07:53 -0800597
598 i_mmap_lock_read(mapping);
599 vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
Jérôme Glissea4d1a882017-08-31 17:17:26 -0400600 unsigned long address, start, end;
Jan Kara4b4bb462016-12-14 15:07:53 -0800601
602 cond_resched();
603
604 if (!(vma->vm_flags & VM_SHARED))
605 continue;
606
607 address = pgoff_address(index, vma);
Jérôme Glissea4d1a882017-08-31 17:17:26 -0400608
609 /*
610 * Note because we provide start/end to follow_pte_pmd it will
611 * call mmu_notifier_invalidate_range_start() on our behalf
612 * before taking any lock.
613 */
614 if (follow_pte_pmd(vma->vm_mm, address, &start, &end, &ptep, &pmdp, &ptl))
Jan Kara4b4bb462016-12-14 15:07:53 -0800615 continue;
Jan Kara4b4bb462016-12-14 15:07:53 -0800616
Jérôme Glisse0f108512017-11-15 17:34:07 -0800617 /*
618 * No need to call mmu_notifier_invalidate_range() as we are
619 * downgrading page table protection not changing it to point
620 * to a new page.
621 *
622 * See Documentation/vm/mmu_notifier.txt
623 */
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800624 if (pmdp) {
625#ifdef CONFIG_FS_DAX_PMD
626 pmd_t pmd;
627
628 if (pfn != pmd_pfn(*pmdp))
629 goto unlock_pmd;
Linus Torvaldsf6f37322017-12-15 18:53:22 -0800630 if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800631 goto unlock_pmd;
632
633 flush_cache_page(vma, address, pfn);
634 pmd = pmdp_huge_clear_flush(vma, address, pmdp);
635 pmd = pmd_wrprotect(pmd);
636 pmd = pmd_mkclean(pmd);
637 set_pmd_at(vma->vm_mm, address, pmdp, pmd);
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800638unlock_pmd:
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800639#endif
Jan H. Schönherree190ca2018-01-31 16:14:04 -0800640 spin_unlock(ptl);
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800641 } else {
642 if (pfn != pte_pfn(*ptep))
643 goto unlock_pte;
644 if (!pte_dirty(*ptep) && !pte_write(*ptep))
645 goto unlock_pte;
646
647 flush_cache_page(vma, address, pfn);
648 pte = ptep_clear_flush(vma, address, ptep);
649 pte = pte_wrprotect(pte);
650 pte = pte_mkclean(pte);
651 set_pte_at(vma->vm_mm, address, ptep, pte);
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800652unlock_pte:
653 pte_unmap_unlock(ptep, ptl);
654 }
Jan Kara4b4bb462016-12-14 15:07:53 -0800655
Jérôme Glissea4d1a882017-08-31 17:17:26 -0400656 mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
Jan Kara4b4bb462016-12-14 15:07:53 -0800657 }
658 i_mmap_unlock_read(mapping);
659}
660
Ross Zwisler9973c982016-01-22 15:10:47 -0800661static int dax_writeback_one(struct block_device *bdev,
Dan Williamscccbce62017-01-27 13:31:42 -0800662 struct dax_device *dax_dev, struct address_space *mapping,
663 pgoff_t index, void *entry)
Ross Zwisler9973c982016-01-22 15:10:47 -0800664{
665 struct radix_tree_root *page_tree = &mapping->page_tree;
Dan Williamscccbce62017-01-27 13:31:42 -0800666 void *entry2, **slot, *kaddr;
667 long ret = 0, id;
668 sector_t sector;
669 pgoff_t pgoff;
670 size_t size;
671 pfn_t pfn;
Ross Zwisler9973c982016-01-22 15:10:47 -0800672
Ross Zwisler9973c982016-01-22 15:10:47 -0800673 /*
Jan Karaa6abc2c2016-12-14 15:07:47 -0800674 * A page got tagged dirty in DAX mapping? Something is seriously
675 * wrong.
Ross Zwisler9973c982016-01-22 15:10:47 -0800676 */
Jan Karaa6abc2c2016-12-14 15:07:47 -0800677 if (WARN_ON(!radix_tree_exceptional_entry(entry)))
678 return -EIO;
Ross Zwisler9973c982016-01-22 15:10:47 -0800679
Jan Karaa6abc2c2016-12-14 15:07:47 -0800680 spin_lock_irq(&mapping->tree_lock);
681 entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
682 /* Entry got punched out / reallocated? */
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700683 if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2)))
Jan Karaa6abc2c2016-12-14 15:07:47 -0800684 goto put_unlocked;
685 /*
686 * Entry got reallocated elsewhere? No need to writeback. We have to
687 * compare sectors as we must not bail out due to difference in lockbit
688 * or entry type.
689 */
690 if (dax_radix_sector(entry2) != dax_radix_sector(entry))
691 goto put_unlocked;
Ross Zwisler642261a2016-11-08 11:34:45 +1100692 if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
693 dax_is_zero_entry(entry))) {
Ross Zwisler9973c982016-01-22 15:10:47 -0800694 ret = -EIO;
Jan Karaa6abc2c2016-12-14 15:07:47 -0800695 goto put_unlocked;
Ross Zwisler9973c982016-01-22 15:10:47 -0800696 }
697
Jan Karaa6abc2c2016-12-14 15:07:47 -0800698 /* Another fsync thread may have already written back this entry */
699 if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
700 goto put_unlocked;
701 /* Lock the entry to serialize with page faults */
702 entry = lock_slot(mapping, slot);
703 /*
704 * We can clear the tag now but we have to be careful so that concurrent
705 * dax_writeback_one() calls for the same index cannot finish before we
706 * actually flush the caches. This is achieved as the calls will look
707 * at the entry only under tree_lock and once they do that they will
708 * see the entry locked and wait for it to unlock.
709 */
710 radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
711 spin_unlock_irq(&mapping->tree_lock);
712
Ross Zwisler642261a2016-11-08 11:34:45 +1100713 /*
714 * Even if dax_writeback_mapping_range() was given a wbc->range_start
715 * in the middle of a PMD, the 'index' we are given will be aligned to
716 * the start index of the PMD, as will the sector we pull from
717 * 'entry'. This allows us to flush for PMD_SIZE and not have to
718 * worry about partial PMD writebacks.
719 */
Dan Williamscccbce62017-01-27 13:31:42 -0800720 sector = dax_radix_sector(entry);
721 size = PAGE_SIZE << dax_radix_order(entry);
722
723 id = dax_read_lock();
724 ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
725 if (ret)
726 goto dax_unlock;
Ross Zwisler9973c982016-01-22 15:10:47 -0800727
728 /*
Dan Williamscccbce62017-01-27 13:31:42 -0800729 * dax_direct_access() may sleep, so cannot hold tree_lock over
730 * its invocation.
Ross Zwisler9973c982016-01-22 15:10:47 -0800731 */
Dan Williamscccbce62017-01-27 13:31:42 -0800732 ret = dax_direct_access(dax_dev, pgoff, size / PAGE_SIZE, &kaddr, &pfn);
733 if (ret < 0)
734 goto dax_unlock;
Ross Zwisler9973c982016-01-22 15:10:47 -0800735
Dan Williamscccbce62017-01-27 13:31:42 -0800736 if (WARN_ON_ONCE(ret < size / PAGE_SIZE)) {
Ross Zwisler9973c982016-01-22 15:10:47 -0800737 ret = -EIO;
Dan Williamscccbce62017-01-27 13:31:42 -0800738 goto dax_unlock;
Ross Zwisler9973c982016-01-22 15:10:47 -0800739 }
740
Dan Williamscccbce62017-01-27 13:31:42 -0800741 dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(pfn));
Mikulas Patockac3ca0152017-08-31 21:47:43 -0400742 dax_flush(dax_dev, kaddr, size);
Jan Kara4b4bb462016-12-14 15:07:53 -0800743 /*
744 * After we have flushed the cache, we can clear the dirty tag. There
745 * cannot be new dirty data in the pfn after the flush has completed as
746 * the pfn mappings are writeprotected and fault waits for mapping
747 * entry lock.
748 */
749 spin_lock_irq(&mapping->tree_lock);
750 radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
751 spin_unlock_irq(&mapping->tree_lock);
Ross Zwislerf9bc3a02017-05-08 16:00:13 -0700752 trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT);
Dan Williamscccbce62017-01-27 13:31:42 -0800753 dax_unlock:
754 dax_read_unlock(id);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700755 put_locked_mapping_entry(mapping, index);
Ross Zwisler9973c982016-01-22 15:10:47 -0800756 return ret;
757
Jan Karaa6abc2c2016-12-14 15:07:47 -0800758 put_unlocked:
759 put_unlocked_mapping_entry(mapping, index, entry2);
Ross Zwisler9973c982016-01-22 15:10:47 -0800760 spin_unlock_irq(&mapping->tree_lock);
761 return ret;
762}
763
764/*
765 * Flush the mapping to the persistent domain within the byte range of [start,
766 * end]. This is required by data integrity operations to ensure file data is
767 * on persistent storage prior to completion of the operation.
768 */
Ross Zwisler7f6d5b52016-02-26 15:19:55 -0800769int dax_writeback_mapping_range(struct address_space *mapping,
770 struct block_device *bdev, struct writeback_control *wbc)
Ross Zwisler9973c982016-01-22 15:10:47 -0800771{
772 struct inode *inode = mapping->host;
Ross Zwisler642261a2016-11-08 11:34:45 +1100773 pgoff_t start_index, end_index;
Ross Zwisler9973c982016-01-22 15:10:47 -0800774 pgoff_t indices[PAGEVEC_SIZE];
Dan Williamscccbce62017-01-27 13:31:42 -0800775 struct dax_device *dax_dev;
Ross Zwisler9973c982016-01-22 15:10:47 -0800776 struct pagevec pvec;
777 bool done = false;
778 int i, ret = 0;
Ross Zwisler9973c982016-01-22 15:10:47 -0800779
780 if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
781 return -EIO;
782
Ross Zwisler7f6d5b52016-02-26 15:19:55 -0800783 if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
784 return 0;
785
Dan Williamscccbce62017-01-27 13:31:42 -0800786 dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
787 if (!dax_dev)
788 return -EIO;
789
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300790 start_index = wbc->range_start >> PAGE_SHIFT;
791 end_index = wbc->range_end >> PAGE_SHIFT;
Ross Zwisler9973c982016-01-22 15:10:47 -0800792
Ross Zwislerd14a3f42017-05-08 16:00:10 -0700793 trace_dax_writeback_range(inode, start_index, end_index);
794
Ross Zwisler9973c982016-01-22 15:10:47 -0800795 tag_pages_for_writeback(mapping, start_index, end_index);
796
Mel Gorman86679822017-11-15 17:37:52 -0800797 pagevec_init(&pvec);
Ross Zwisler9973c982016-01-22 15:10:47 -0800798 while (!done) {
799 pvec.nr = find_get_entries_tag(mapping, start_index,
800 PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
801 pvec.pages, indices);
802
803 if (pvec.nr == 0)
804 break;
805
806 for (i = 0; i < pvec.nr; i++) {
807 if (indices[i] > end_index) {
808 done = true;
809 break;
810 }
811
Dan Williamscccbce62017-01-27 13:31:42 -0800812 ret = dax_writeback_one(bdev, dax_dev, mapping,
813 indices[i], pvec.pages[i]);
Jeff Layton819ec6b2017-07-06 07:02:27 -0400814 if (ret < 0) {
815 mapping_set_error(mapping, ret);
Ross Zwislerd14a3f42017-05-08 16:00:10 -0700816 goto out;
Jeff Layton819ec6b2017-07-06 07:02:27 -0400817 }
Ross Zwisler9973c982016-01-22 15:10:47 -0800818 }
Jan Kara1eb643d2017-06-23 15:08:46 -0700819 start_index = indices[pvec.nr - 1] + 1;
Ross Zwisler9973c982016-01-22 15:10:47 -0800820 }
Ross Zwislerd14a3f42017-05-08 16:00:10 -0700821out:
Dan Williamscccbce62017-01-27 13:31:42 -0800822 put_dax(dax_dev);
Ross Zwislerd14a3f42017-05-08 16:00:10 -0700823 trace_dax_writeback_range_done(inode, start_index, end_index);
824 return (ret < 0 ? ret : 0);
Ross Zwisler9973c982016-01-22 15:10:47 -0800825}
826EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
827
Jan Kara31a6f1a2017-11-01 16:36:32 +0100828static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800829{
Linus Torvaldsa3841f92017-11-17 09:51:57 -0800830 return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
Jan Kara31a6f1a2017-11-01 16:36:32 +0100831}
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800832
Jan Kara5e161e42017-11-01 16:36:33 +0100833static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
834 pfn_t *pfnp)
835{
836 const sector_t sector = dax_iomap_sector(iomap, pos);
837 pgoff_t pgoff;
838 void *kaddr;
839 int id, rc;
840 long length;
841
842 rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff);
Dan Williamscccbce62017-01-27 13:31:42 -0800843 if (rc)
844 return rc;
Dan Williamscccbce62017-01-27 13:31:42 -0800845 id = dax_read_lock();
Jan Kara5e161e42017-11-01 16:36:33 +0100846 length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
847 &kaddr, pfnp);
848 if (length < 0) {
849 rc = length;
850 goto out;
Dan Williamscccbce62017-01-27 13:31:42 -0800851 }
Jan Kara5e161e42017-11-01 16:36:33 +0100852 rc = -EINVAL;
853 if (PFN_PHYS(length) < size)
854 goto out;
855 if (pfn_t_to_pfn(*pfnp) & (PHYS_PFN(size)-1))
856 goto out;
857 /* For larger pages we need devmap */
858 if (length > 1 && !pfn_t_devmap(*pfnp))
859 goto out;
860 rc = 0;
861out:
Dan Williamscccbce62017-01-27 13:31:42 -0800862 dax_read_unlock(id);
Jan Kara5e161e42017-11-01 16:36:33 +0100863 return rc;
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800864}
865
Ross Zwislere30331f2017-09-06 16:18:39 -0700866/*
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700867 * The user has performed a load from a hole in the file. Allocating a new
868 * page in the file would cause excessive storage usage for workloads with
869 * sparse files. Instead we insert a read-only mapping of the 4k zero page.
870 * If this page is ever written to we will re-fault and change the mapping to
871 * point to real DAX storage instead.
Ross Zwislere30331f2017-09-06 16:18:39 -0700872 */
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700873static int dax_load_hole(struct address_space *mapping, void *entry,
Ross Zwislere30331f2017-09-06 16:18:39 -0700874 struct vm_fault *vmf)
875{
876 struct inode *inode = mapping->host;
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700877 unsigned long vaddr = vmf->address;
878 int ret = VM_FAULT_NOPAGE;
879 struct page *zero_page;
880 void *entry2;
Ross Zwislere30331f2017-09-06 16:18:39 -0700881
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700882 zero_page = ZERO_PAGE(0);
883 if (unlikely(!zero_page)) {
Ross Zwislere30331f2017-09-06 16:18:39 -0700884 ret = VM_FAULT_OOM;
885 goto out;
886 }
887
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700888 entry2 = dax_insert_mapping_entry(mapping, vmf, entry, 0,
Jan Karaf5b7b742017-11-01 16:36:40 +0100889 RADIX_DAX_ZERO_PAGE, false);
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700890 if (IS_ERR(entry2)) {
891 ret = VM_FAULT_SIGBUS;
892 goto out;
Ross Zwislere30331f2017-09-06 16:18:39 -0700893 }
Ross Zwisler91d25ba2017-09-06 16:18:43 -0700894
895 vm_insert_mixed(vmf->vma, vaddr, page_to_pfn_t(zero_page));
Ross Zwislere30331f2017-09-06 16:18:39 -0700896out:
897 trace_dax_load_hole(inode, vmf, ret);
898 return ret;
899}
900
Vishal Verma4b0228f2016-04-21 15:13:46 -0400901static bool dax_range_is_aligned(struct block_device *bdev,
902 unsigned int offset, unsigned int length)
903{
904 unsigned short sector_size = bdev_logical_block_size(bdev);
905
906 if (!IS_ALIGNED(offset, sector_size))
907 return false;
908 if (!IS_ALIGNED(length, sector_size))
909 return false;
910
911 return true;
912}
913
Dan Williamscccbce62017-01-27 13:31:42 -0800914int __dax_zero_page_range(struct block_device *bdev,
915 struct dax_device *dax_dev, sector_t sector,
916 unsigned int offset, unsigned int size)
Christoph Hellwig679c8bd2016-05-09 10:47:04 +0200917{
Dan Williamscccbce62017-01-27 13:31:42 -0800918 if (dax_range_is_aligned(bdev, offset, size)) {
919 sector_t start_sector = sector + (offset >> 9);
Vishal Verma4b0228f2016-04-21 15:13:46 -0400920
921 return blkdev_issue_zeroout(bdev, start_sector,
Linus Torvalds53ef7d02017-05-05 18:49:20 -0700922 size >> 9, GFP_NOFS, 0);
Vishal Verma4b0228f2016-04-21 15:13:46 -0400923 } else {
Dan Williamscccbce62017-01-27 13:31:42 -0800924 pgoff_t pgoff;
925 long rc, id;
926 void *kaddr;
927 pfn_t pfn;
928
Dan Williamse84b83b2017-05-10 19:38:13 -0700929 rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
Dan Williamscccbce62017-01-27 13:31:42 -0800930 if (rc)
931 return rc;
932
933 id = dax_read_lock();
Dan Williamse84b83b2017-05-10 19:38:13 -0700934 rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr,
Dan Williamscccbce62017-01-27 13:31:42 -0800935 &pfn);
936 if (rc < 0) {
937 dax_read_unlock(id);
938 return rc;
939 }
Dan Williams81f55872017-05-29 13:12:20 -0700940 memset(kaddr + offset, 0, size);
Mikulas Patockac3ca0152017-08-31 21:47:43 -0400941 dax_flush(dax_dev, kaddr + offset, size);
Dan Williamscccbce62017-01-27 13:31:42 -0800942 dax_read_unlock(id);
Vishal Verma4b0228f2016-04-21 15:13:46 -0400943 }
Christoph Hellwig679c8bd2016-05-09 10:47:04 +0200944 return 0;
945}
946EXPORT_SYMBOL_GPL(__dax_zero_page_range);
947
Christoph Hellwiga254e562016-09-19 11:24:49 +1000948static loff_t
Ross Zwisler11c59c92016-11-08 11:32:46 +1100949dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
Christoph Hellwiga254e562016-09-19 11:24:49 +1000950 struct iomap *iomap)
951{
Dan Williamscccbce62017-01-27 13:31:42 -0800952 struct block_device *bdev = iomap->bdev;
953 struct dax_device *dax_dev = iomap->dax_dev;
Christoph Hellwiga254e562016-09-19 11:24:49 +1000954 struct iov_iter *iter = data;
955 loff_t end = pos + length, done = 0;
956 ssize_t ret = 0;
Dan Williamscccbce62017-01-27 13:31:42 -0800957 int id;
Christoph Hellwiga254e562016-09-19 11:24:49 +1000958
959 if (iov_iter_rw(iter) == READ) {
960 end = min(end, i_size_read(inode));
961 if (pos >= end)
962 return 0;
963
964 if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
965 return iov_iter_zero(min(length, end - pos), iter);
966 }
967
968 if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
969 return -EIO;
970
Jan Karae3fce682016-08-10 17:10:28 +0200971 /*
972 * Write can allocate block for an area which has a hole page mapped
973 * into page tables. We have to tear down these mappings so that data
974 * written by write(2) is visible in mmap.
975 */
Jan Karacd656372017-05-12 15:46:50 -0700976 if (iomap->flags & IOMAP_F_NEW) {
Jan Karae3fce682016-08-10 17:10:28 +0200977 invalidate_inode_pages2_range(inode->i_mapping,
978 pos >> PAGE_SHIFT,
979 (end - 1) >> PAGE_SHIFT);
980 }
981
Dan Williamscccbce62017-01-27 13:31:42 -0800982 id = dax_read_lock();
Christoph Hellwiga254e562016-09-19 11:24:49 +1000983 while (pos < end) {
984 unsigned offset = pos & (PAGE_SIZE - 1);
Dan Williamscccbce62017-01-27 13:31:42 -0800985 const size_t size = ALIGN(length + offset, PAGE_SIZE);
986 const sector_t sector = dax_iomap_sector(iomap, pos);
Christoph Hellwiga254e562016-09-19 11:24:49 +1000987 ssize_t map_len;
Dan Williamscccbce62017-01-27 13:31:42 -0800988 pgoff_t pgoff;
989 void *kaddr;
990 pfn_t pfn;
Christoph Hellwiga254e562016-09-19 11:24:49 +1000991
Michal Hockod1908f52017-02-03 13:13:26 -0800992 if (fatal_signal_pending(current)) {
993 ret = -EINTR;
994 break;
995 }
996
Dan Williamscccbce62017-01-27 13:31:42 -0800997 ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
998 if (ret)
999 break;
1000
1001 map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
1002 &kaddr, &pfn);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001003 if (map_len < 0) {
1004 ret = map_len;
1005 break;
1006 }
1007
Dan Williamscccbce62017-01-27 13:31:42 -08001008 map_len = PFN_PHYS(map_len);
1009 kaddr += offset;
Christoph Hellwiga254e562016-09-19 11:24:49 +10001010 map_len -= offset;
1011 if (map_len > end - pos)
1012 map_len = end - pos;
1013
Ross Zwislera2e050f2017-09-06 16:18:54 -07001014 /*
1015 * The userspace address for the memory copy has already been
1016 * validated via access_ok() in either vfs_read() or
1017 * vfs_write(), depending on which operation we are doing.
1018 */
Christoph Hellwiga254e562016-09-19 11:24:49 +10001019 if (iov_iter_rw(iter) == WRITE)
Dan Williamsfec53772017-05-29 21:56:49 -07001020 map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr,
1021 map_len, iter);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001022 else
Dan Williamscccbce62017-01-27 13:31:42 -08001023 map_len = copy_to_iter(kaddr, map_len, iter);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001024 if (map_len <= 0) {
1025 ret = map_len ? map_len : -EFAULT;
1026 break;
1027 }
1028
1029 pos += map_len;
1030 length -= map_len;
1031 done += map_len;
1032 }
Dan Williamscccbce62017-01-27 13:31:42 -08001033 dax_read_unlock(id);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001034
1035 return done ? done : ret;
1036}
1037
1038/**
Ross Zwisler11c59c92016-11-08 11:32:46 +11001039 * dax_iomap_rw - Perform I/O to a DAX file
Christoph Hellwiga254e562016-09-19 11:24:49 +10001040 * @iocb: The control block for this I/O
1041 * @iter: The addresses to do I/O from or to
1042 * @ops: iomap ops passed from the file system
1043 *
1044 * This function performs read and write operations to directly mapped
1045 * persistent memory. The callers needs to take care of read/write exclusion
1046 * and evicting any page cache pages in the region under I/O.
1047 */
1048ssize_t
Ross Zwisler11c59c92016-11-08 11:32:46 +11001049dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
Christoph Hellwig8ff6daa2017-01-27 23:20:26 -08001050 const struct iomap_ops *ops)
Christoph Hellwiga254e562016-09-19 11:24:49 +10001051{
1052 struct address_space *mapping = iocb->ki_filp->f_mapping;
1053 struct inode *inode = mapping->host;
1054 loff_t pos = iocb->ki_pos, ret = 0, done = 0;
1055 unsigned flags = 0;
1056
Christoph Hellwig168316d2017-02-08 14:43:13 -05001057 if (iov_iter_rw(iter) == WRITE) {
1058 lockdep_assert_held_exclusive(&inode->i_rwsem);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001059 flags |= IOMAP_WRITE;
Christoph Hellwig168316d2017-02-08 14:43:13 -05001060 } else {
1061 lockdep_assert_held(&inode->i_rwsem);
1062 }
Christoph Hellwiga254e562016-09-19 11:24:49 +10001063
Christoph Hellwiga254e562016-09-19 11:24:49 +10001064 while (iov_iter_count(iter)) {
1065 ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
Ross Zwisler11c59c92016-11-08 11:32:46 +11001066 iter, dax_iomap_actor);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001067 if (ret <= 0)
1068 break;
1069 pos += ret;
1070 done += ret;
1071 }
1072
1073 iocb->ki_pos += done;
1074 return done ? done : ret;
1075}
Ross Zwisler11c59c92016-11-08 11:32:46 +11001076EXPORT_SYMBOL_GPL(dax_iomap_rw);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001077
Jan Kara9f141d62016-10-19 14:34:31 +02001078static int dax_fault_return(int error)
1079{
1080 if (error == 0)
1081 return VM_FAULT_NOPAGE;
1082 if (error == -ENOMEM)
1083 return VM_FAULT_OOM;
1084 return VM_FAULT_SIGBUS;
1085}
1086
Dan Williamsaaa422c2017-11-13 16:38:44 -08001087/*
1088 * MAP_SYNC on a dax mapping guarantees dirty metadata is
1089 * flushed on write-faults (non-cow), but not read-faults.
1090 */
1091static bool dax_fault_is_synchronous(unsigned long flags,
1092 struct vm_area_struct *vma, struct iomap *iomap)
1093{
1094 return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC)
1095 && (iomap->flags & IOMAP_F_DIRTY);
1096}
1097
Jan Kara9a0dd422017-11-01 16:36:39 +01001098static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
Dave Jianga2d58162017-02-24 14:56:59 -08001099 const struct iomap_ops *ops)
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001100{
Jan Karaa0987ad2017-11-01 16:36:34 +01001101 struct vm_area_struct *vma = vmf->vma;
1102 struct address_space *mapping = vma->vm_file->f_mapping;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001103 struct inode *inode = mapping->host;
Jan Kara1a29d852016-12-14 15:07:01 -08001104 unsigned long vaddr = vmf->address;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001105 loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001106 struct iomap iomap = { 0 };
Jan Kara9484ab12016-11-10 10:26:50 +11001107 unsigned flags = IOMAP_FAULT;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001108 int error, major = 0;
Jan Karad2c43ef2017-11-01 16:36:35 +01001109 bool write = vmf->flags & FAULT_FLAG_WRITE;
Jan Karacaa51d22017-11-01 16:36:42 +01001110 bool sync;
Jan Karab1aa8122016-12-14 15:07:24 -08001111 int vmf_ret = 0;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001112 void *entry;
Jan Kara1b5a1cb2017-11-01 16:36:36 +01001113 pfn_t pfn;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001114
Ross Zwislera9c42b32017-05-08 16:00:00 -07001115 trace_dax_pte_fault(inode, vmf, vmf_ret);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001116 /*
1117 * Check whether offset isn't beyond end of file now. Caller is supposed
1118 * to hold locks serializing us with truncate / punch hole so this is
1119 * a reliable test.
1120 */
Ross Zwislera9c42b32017-05-08 16:00:00 -07001121 if (pos >= i_size_read(inode)) {
1122 vmf_ret = VM_FAULT_SIGBUS;
1123 goto out;
1124 }
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001125
Jan Karad2c43ef2017-11-01 16:36:35 +01001126 if (write && !vmf->cow_page)
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001127 flags |= IOMAP_WRITE;
1128
Jan Kara13e451f2017-05-12 15:46:57 -07001129 entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
1130 if (IS_ERR(entry)) {
1131 vmf_ret = dax_fault_return(PTR_ERR(entry));
1132 goto out;
1133 }
1134
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001135 /*
Ross Zwislere2093922017-06-02 14:46:37 -07001136 * It is possible, particularly with mixed reads & writes to private
1137 * mappings, that we have raced with a PMD fault that overlaps with
1138 * the PTE we need to set up. If so just return and the fault will be
1139 * retried.
1140 */
1141 if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) {
1142 vmf_ret = VM_FAULT_NOPAGE;
1143 goto unlock_entry;
1144 }
1145
1146 /*
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001147 * Note that we don't bother to use iomap_apply here: DAX required
1148 * the file system block size to be equal the page size, which means
1149 * that we never have to deal with more than a single extent here.
1150 */
1151 error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
Ross Zwislera9c42b32017-05-08 16:00:00 -07001152 if (error) {
1153 vmf_ret = dax_fault_return(error);
Jan Kara13e451f2017-05-12 15:46:57 -07001154 goto unlock_entry;
Ross Zwislera9c42b32017-05-08 16:00:00 -07001155 }
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001156 if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
Jan Kara13e451f2017-05-12 15:46:57 -07001157 error = -EIO; /* fs corruption? */
1158 goto error_finish_iomap;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001159 }
1160
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001161 if (vmf->cow_page) {
Jan Kara31a6f1a2017-11-01 16:36:32 +01001162 sector_t sector = dax_iomap_sector(&iomap, pos);
1163
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001164 switch (iomap.type) {
1165 case IOMAP_HOLE:
1166 case IOMAP_UNWRITTEN:
1167 clear_user_highpage(vmf->cow_page, vaddr);
1168 break;
1169 case IOMAP_MAPPED:
Dan Williamscccbce62017-01-27 13:31:42 -08001170 error = copy_user_dax(iomap.bdev, iomap.dax_dev,
1171 sector, PAGE_SIZE, vmf->cow_page, vaddr);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001172 break;
1173 default:
1174 WARN_ON_ONCE(1);
1175 error = -EIO;
1176 break;
1177 }
1178
1179 if (error)
Jan Kara13e451f2017-05-12 15:46:57 -07001180 goto error_finish_iomap;
Jan Karab1aa8122016-12-14 15:07:24 -08001181
1182 __SetPageUptodate(vmf->cow_page);
1183 vmf_ret = finish_fault(vmf);
1184 if (!vmf_ret)
1185 vmf_ret = VM_FAULT_DONE_COW;
Jan Kara13e451f2017-05-12 15:46:57 -07001186 goto finish_iomap;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001187 }
1188
Dan Williamsaaa422c2017-11-13 16:38:44 -08001189 sync = dax_fault_is_synchronous(flags, vma, &iomap);
Jan Karacaa51d22017-11-01 16:36:42 +01001190
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001191 switch (iomap.type) {
1192 case IOMAP_MAPPED:
1193 if (iomap.flags & IOMAP_F_NEW) {
1194 count_vm_event(PGMAJFAULT);
Jan Karaa0987ad2017-11-01 16:36:34 +01001195 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001196 major = VM_FAULT_MAJOR;
1197 }
Jan Kara1b5a1cb2017-11-01 16:36:36 +01001198 error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn);
1199 if (error < 0)
1200 goto error_finish_iomap;
1201
1202 entry = dax_insert_mapping_entry(mapping, vmf, entry,
1203 dax_iomap_sector(&iomap, pos),
Jan Karacaa51d22017-11-01 16:36:42 +01001204 0, write && !sync);
Jan Kara1b5a1cb2017-11-01 16:36:36 +01001205 if (IS_ERR(entry)) {
1206 error = PTR_ERR(entry);
1207 goto error_finish_iomap;
1208 }
1209
Jan Karacaa51d22017-11-01 16:36:42 +01001210 /*
1211 * If we are doing synchronous page fault and inode needs fsync,
1212 * we can insert PTE into page tables only after that happens.
1213 * Skip insertion for now and return the pfn so that caller can
1214 * insert it after fsync is done.
1215 */
1216 if (sync) {
1217 if (WARN_ON_ONCE(!pfnp)) {
1218 error = -EIO;
1219 goto error_finish_iomap;
1220 }
1221 *pfnp = pfn;
1222 vmf_ret = VM_FAULT_NEEDDSYNC | major;
1223 goto finish_iomap;
1224 }
Jan Kara1b5a1cb2017-11-01 16:36:36 +01001225 trace_dax_insert_mapping(inode, vmf, entry);
1226 if (write)
1227 error = vm_insert_mixed_mkwrite(vma, vaddr, pfn);
1228 else
1229 error = vm_insert_mixed(vma, vaddr, pfn);
1230
Jan Kara9f141d62016-10-19 14:34:31 +02001231 /* -EBUSY is fine, somebody else faulted on the same PTE */
1232 if (error == -EBUSY)
1233 error = 0;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001234 break;
1235 case IOMAP_UNWRITTEN:
1236 case IOMAP_HOLE:
Jan Karad2c43ef2017-11-01 16:36:35 +01001237 if (!write) {
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001238 vmf_ret = dax_load_hole(mapping, entry, vmf);
Jan Kara13e451f2017-05-12 15:46:57 -07001239 goto finish_iomap;
Ross Zwisler15502902016-11-08 11:33:26 +11001240 }
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001241 /*FALLTHRU*/
1242 default:
1243 WARN_ON_ONCE(1);
1244 error = -EIO;
1245 break;
1246 }
1247
Jan Kara13e451f2017-05-12 15:46:57 -07001248 error_finish_iomap:
Jan Kara9f141d62016-10-19 14:34:31 +02001249 vmf_ret = dax_fault_return(error) | major;
Jan Kara9f141d62016-10-19 14:34:31 +02001250 finish_iomap:
1251 if (ops->iomap_end) {
1252 int copied = PAGE_SIZE;
1253
1254 if (vmf_ret & VM_FAULT_ERROR)
1255 copied = 0;
1256 /*
1257 * The fault is done by now and there's no way back (other
1258 * thread may be already happily using PTE we have installed).
1259 * Just ignore error from ->iomap_end since we cannot do much
1260 * with it.
1261 */
1262 ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
Ross Zwisler15502902016-11-08 11:33:26 +11001263 }
Jan Kara13e451f2017-05-12 15:46:57 -07001264 unlock_entry:
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001265 put_locked_mapping_entry(mapping, vmf->pgoff);
Jan Kara13e451f2017-05-12 15:46:57 -07001266 out:
Ross Zwislera9c42b32017-05-08 16:00:00 -07001267 trace_dax_pte_fault_done(inode, vmf, vmf_ret);
Jan Kara9f141d62016-10-19 14:34:31 +02001268 return vmf_ret;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001269}
Ross Zwisler642261a2016-11-08 11:34:45 +11001270
1271#ifdef CONFIG_FS_DAX_PMD
Jan Kara302a5e32017-11-01 16:36:37 +01001272/*
1273 * The 'colour' (ie low bits) within a PMD of a page offset. This comes up
1274 * more often than one might expect in the below functions.
1275 */
1276#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
Ross Zwisler642261a2016-11-08 11:34:45 +11001277
Dave Jiangf4200392017-02-22 15:40:06 -08001278static int dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001279 void *entry)
Ross Zwisler642261a2016-11-08 11:34:45 +11001280{
Dave Jiangf4200392017-02-22 15:40:06 -08001281 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
1282 unsigned long pmd_addr = vmf->address & PMD_MASK;
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001283 struct inode *inode = mapping->host;
Ross Zwisler642261a2016-11-08 11:34:45 +11001284 struct page *zero_page;
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001285 void *ret = NULL;
Ross Zwisler642261a2016-11-08 11:34:45 +11001286 spinlock_t *ptl;
1287 pmd_t pmd_entry;
Ross Zwisler642261a2016-11-08 11:34:45 +11001288
Dave Jiangf4200392017-02-22 15:40:06 -08001289 zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm);
Ross Zwisler642261a2016-11-08 11:34:45 +11001290
1291 if (unlikely(!zero_page))
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001292 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001293
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001294 ret = dax_insert_mapping_entry(mapping, vmf, entry, 0,
Jan Karaf5b7b742017-11-01 16:36:40 +01001295 RADIX_DAX_PMD | RADIX_DAX_ZERO_PAGE, false);
Ross Zwisler642261a2016-11-08 11:34:45 +11001296 if (IS_ERR(ret))
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001297 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001298
Dave Jiangf4200392017-02-22 15:40:06 -08001299 ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1300 if (!pmd_none(*(vmf->pmd))) {
Ross Zwisler642261a2016-11-08 11:34:45 +11001301 spin_unlock(ptl);
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001302 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001303 }
1304
Dave Jiangf4200392017-02-22 15:40:06 -08001305 pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
Ross Zwisler642261a2016-11-08 11:34:45 +11001306 pmd_entry = pmd_mkhuge(pmd_entry);
Dave Jiangf4200392017-02-22 15:40:06 -08001307 set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
Ross Zwisler642261a2016-11-08 11:34:45 +11001308 spin_unlock(ptl);
Dave Jiangf4200392017-02-22 15:40:06 -08001309 trace_dax_pmd_load_hole(inode, vmf, zero_page, ret);
Ross Zwisler642261a2016-11-08 11:34:45 +11001310 return VM_FAULT_NOPAGE;
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001311
1312fallback:
Dave Jiangf4200392017-02-22 15:40:06 -08001313 trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, ret);
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001314 return VM_FAULT_FALLBACK;
Ross Zwisler642261a2016-11-08 11:34:45 +11001315}
1316
Jan Kara9a0dd422017-11-01 16:36:39 +01001317static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
Dave Jianga2d58162017-02-24 14:56:59 -08001318 const struct iomap_ops *ops)
Ross Zwisler642261a2016-11-08 11:34:45 +11001319{
Dave Jiangf4200392017-02-22 15:40:06 -08001320 struct vm_area_struct *vma = vmf->vma;
Ross Zwisler642261a2016-11-08 11:34:45 +11001321 struct address_space *mapping = vma->vm_file->f_mapping;
Dave Jiangd8a849e2017-02-22 15:40:03 -08001322 unsigned long pmd_addr = vmf->address & PMD_MASK;
1323 bool write = vmf->flags & FAULT_FLAG_WRITE;
Jan Karacaa51d22017-11-01 16:36:42 +01001324 bool sync;
Jan Kara9484ab12016-11-10 10:26:50 +11001325 unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
Ross Zwisler642261a2016-11-08 11:34:45 +11001326 struct inode *inode = mapping->host;
1327 int result = VM_FAULT_FALLBACK;
1328 struct iomap iomap = { 0 };
1329 pgoff_t max_pgoff, pgoff;
Ross Zwisler642261a2016-11-08 11:34:45 +11001330 void *entry;
1331 loff_t pos;
1332 int error;
Jan Kara302a5e32017-11-01 16:36:37 +01001333 pfn_t pfn;
Ross Zwisler642261a2016-11-08 11:34:45 +11001334
Ross Zwisler282a8e02017-02-22 15:39:50 -08001335 /*
1336 * Check whether offset isn't beyond end of file now. Caller is
1337 * supposed to hold locks serializing us with truncate / punch hole so
1338 * this is a reliable test.
1339 */
1340 pgoff = linear_page_index(vma, pmd_addr);
Jeff Moyer957ac8c2017-11-14 20:37:27 -05001341 max_pgoff = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
Ross Zwisler282a8e02017-02-22 15:39:50 -08001342
Dave Jiangf4200392017-02-22 15:40:06 -08001343 trace_dax_pmd_fault(inode, vmf, max_pgoff, 0);
Ross Zwisler282a8e02017-02-22 15:39:50 -08001344
Ross Zwislerfffa2812017-08-25 15:55:36 -07001345 /*
1346 * Make sure that the faulting address's PMD offset (color) matches
1347 * the PMD offset from the start of the file. This is necessary so
1348 * that a PMD range in the page table overlaps exactly with a PMD
1349 * range in the radix tree.
1350 */
1351 if ((vmf->pgoff & PG_PMD_COLOUR) !=
1352 ((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR))
1353 goto fallback;
1354
Ross Zwisler642261a2016-11-08 11:34:45 +11001355 /* Fall back to PTEs if we're going to COW */
1356 if (write && !(vma->vm_flags & VM_SHARED))
1357 goto fallback;
1358
1359 /* If the PMD would extend outside the VMA */
1360 if (pmd_addr < vma->vm_start)
1361 goto fallback;
1362 if ((pmd_addr + PMD_SIZE) > vma->vm_end)
1363 goto fallback;
1364
Jeff Moyer957ac8c2017-11-14 20:37:27 -05001365 if (pgoff >= max_pgoff) {
Ross Zwisler282a8e02017-02-22 15:39:50 -08001366 result = VM_FAULT_SIGBUS;
1367 goto out;
1368 }
Ross Zwisler642261a2016-11-08 11:34:45 +11001369
1370 /* If the PMD would extend beyond the file size */
Jeff Moyer957ac8c2017-11-14 20:37:27 -05001371 if ((pgoff | PG_PMD_COLOUR) >= max_pgoff)
Ross Zwisler642261a2016-11-08 11:34:45 +11001372 goto fallback;
1373
1374 /*
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001375 * grab_mapping_entry() will make sure we get a 2MiB empty entry, a
1376 * 2MiB zero page entry or a DAX PMD. If it can't (because a 4k page
1377 * is already in the tree, for instance), it will return -EEXIST and
1378 * we just fall back to 4k entries.
Jan Kara9f141d62016-10-19 14:34:31 +02001379 */
1380 entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
1381 if (IS_ERR(entry))
Ross Zwisler876f2942017-05-12 15:47:00 -07001382 goto fallback;
1383
1384 /*
Ross Zwislere2093922017-06-02 14:46:37 -07001385 * It is possible, particularly with mixed reads & writes to private
1386 * mappings, that we have raced with a PTE fault that overlaps with
1387 * the PMD we need to set up. If so just return and the fault will be
1388 * retried.
1389 */
1390 if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) &&
1391 !pmd_devmap(*vmf->pmd)) {
1392 result = 0;
1393 goto unlock_entry;
1394 }
1395
1396 /*
Ross Zwisler876f2942017-05-12 15:47:00 -07001397 * Note that we don't use iomap_apply here. We aren't doing I/O, only
1398 * setting up a mapping, so really we're using iomap_begin() as a way
1399 * to look up our filesystem block.
1400 */
1401 pos = (loff_t)pgoff << PAGE_SHIFT;
1402 error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
1403 if (error)
1404 goto unlock_entry;
1405
1406 if (iomap.offset + iomap.length < pos + PMD_SIZE)
Jan Kara9f141d62016-10-19 14:34:31 +02001407 goto finish_iomap;
1408
Dan Williamsaaa422c2017-11-13 16:38:44 -08001409 sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap);
Jan Karacaa51d22017-11-01 16:36:42 +01001410
Ross Zwisler642261a2016-11-08 11:34:45 +11001411 switch (iomap.type) {
1412 case IOMAP_MAPPED:
Jan Kara302a5e32017-11-01 16:36:37 +01001413 error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn);
1414 if (error < 0)
1415 goto finish_iomap;
1416
1417 entry = dax_insert_mapping_entry(mapping, vmf, entry,
1418 dax_iomap_sector(&iomap, pos),
Jan Karacaa51d22017-11-01 16:36:42 +01001419 RADIX_DAX_PMD, write && !sync);
Jan Kara302a5e32017-11-01 16:36:37 +01001420 if (IS_ERR(entry))
1421 goto finish_iomap;
1422
Jan Karacaa51d22017-11-01 16:36:42 +01001423 /*
1424 * If we are doing synchronous page fault and inode needs fsync,
1425 * we can insert PMD into page tables only after that happens.
1426 * Skip insertion for now and return the pfn so that caller can
1427 * insert it after fsync is done.
1428 */
1429 if (sync) {
1430 if (WARN_ON_ONCE(!pfnp))
1431 goto finish_iomap;
1432 *pfnp = pfn;
1433 result = VM_FAULT_NEEDDSYNC;
1434 goto finish_iomap;
1435 }
1436
Jan Kara302a5e32017-11-01 16:36:37 +01001437 trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry);
1438 result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn,
1439 write);
Ross Zwisler642261a2016-11-08 11:34:45 +11001440 break;
1441 case IOMAP_UNWRITTEN:
1442 case IOMAP_HOLE:
1443 if (WARN_ON_ONCE(write))
Ross Zwisler876f2942017-05-12 15:47:00 -07001444 break;
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001445 result = dax_pmd_load_hole(vmf, &iomap, entry);
Ross Zwisler642261a2016-11-08 11:34:45 +11001446 break;
1447 default:
1448 WARN_ON_ONCE(1);
1449 break;
1450 }
1451
Jan Kara9f141d62016-10-19 14:34:31 +02001452 finish_iomap:
1453 if (ops->iomap_end) {
1454 int copied = PMD_SIZE;
1455
1456 if (result == VM_FAULT_FALLBACK)
1457 copied = 0;
1458 /*
1459 * The fault is done by now and there's no way back (other
1460 * thread may be already happily using PMD we have installed).
1461 * Just ignore error from ->iomap_end since we cannot do much
1462 * with it.
1463 */
1464 ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
1465 &iomap);
1466 }
Ross Zwisler876f2942017-05-12 15:47:00 -07001467 unlock_entry:
Ross Zwisler91d25ba2017-09-06 16:18:43 -07001468 put_locked_mapping_entry(mapping, pgoff);
Ross Zwisler642261a2016-11-08 11:34:45 +11001469 fallback:
1470 if (result == VM_FAULT_FALLBACK) {
Dave Jiangd8a849e2017-02-22 15:40:03 -08001471 split_huge_pmd(vma, vmf->pmd, vmf->address);
Ross Zwisler642261a2016-11-08 11:34:45 +11001472 count_vm_event(THP_FAULT_FALLBACK);
1473 }
Ross Zwisler282a8e02017-02-22 15:39:50 -08001474out:
Dave Jiangf4200392017-02-22 15:40:06 -08001475 trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result);
Ross Zwisler642261a2016-11-08 11:34:45 +11001476 return result;
1477}
Dave Jianga2d58162017-02-24 14:56:59 -08001478#else
Jan Kara9a0dd422017-11-01 16:36:39 +01001479static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
Arnd Bergmann01cddfe2017-02-27 14:26:44 -08001480 const struct iomap_ops *ops)
Dave Jianga2d58162017-02-24 14:56:59 -08001481{
1482 return VM_FAULT_FALLBACK;
1483}
Ross Zwisler642261a2016-11-08 11:34:45 +11001484#endif /* CONFIG_FS_DAX_PMD */
Dave Jianga2d58162017-02-24 14:56:59 -08001485
1486/**
1487 * dax_iomap_fault - handle a page fault on a DAX file
1488 * @vmf: The description of the fault
Jan Karacec04e82017-11-01 16:36:38 +01001489 * @pe_size: Size of the page to fault in
Jan Kara9a0dd422017-11-01 16:36:39 +01001490 * @pfnp: PFN to insert for synchronous faults if fsync is required
Jan Karacec04e82017-11-01 16:36:38 +01001491 * @ops: Iomap ops passed from the file system
Dave Jianga2d58162017-02-24 14:56:59 -08001492 *
1493 * When a page fault occurs, filesystems may call this helper in
1494 * their fault handler for DAX files. dax_iomap_fault() assumes the caller
1495 * has done all the necessary locking for page fault to proceed
1496 * successfully.
1497 */
Dave Jiangc791ace2017-02-24 14:57:08 -08001498int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
Jan Kara9a0dd422017-11-01 16:36:39 +01001499 pfn_t *pfnp, const struct iomap_ops *ops)
Dave Jianga2d58162017-02-24 14:56:59 -08001500{
Dave Jiangc791ace2017-02-24 14:57:08 -08001501 switch (pe_size) {
1502 case PE_SIZE_PTE:
Jan Kara9a0dd422017-11-01 16:36:39 +01001503 return dax_iomap_pte_fault(vmf, pfnp, ops);
Dave Jiangc791ace2017-02-24 14:57:08 -08001504 case PE_SIZE_PMD:
Jan Kara9a0dd422017-11-01 16:36:39 +01001505 return dax_iomap_pmd_fault(vmf, pfnp, ops);
Dave Jianga2d58162017-02-24 14:56:59 -08001506 default:
1507 return VM_FAULT_FALLBACK;
1508 }
1509}
1510EXPORT_SYMBOL_GPL(dax_iomap_fault);
Jan Kara71eab6d2017-11-01 16:36:43 +01001511
1512/**
1513 * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables
1514 * @vmf: The description of the fault
1515 * @pe_size: Size of entry to be inserted
1516 * @pfn: PFN to insert
1517 *
1518 * This function inserts writeable PTE or PMD entry into page tables for mmaped
1519 * DAX file. It takes care of marking corresponding radix tree entry as dirty
1520 * as well.
1521 */
1522static int dax_insert_pfn_mkwrite(struct vm_fault *vmf,
1523 enum page_entry_size pe_size,
1524 pfn_t pfn)
1525{
1526 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
1527 void *entry, **slot;
1528 pgoff_t index = vmf->pgoff;
1529 int vmf_ret, error;
1530
1531 spin_lock_irq(&mapping->tree_lock);
1532 entry = get_unlocked_mapping_entry(mapping, index, &slot);
1533 /* Did we race with someone splitting entry or so? */
1534 if (!entry ||
1535 (pe_size == PE_SIZE_PTE && !dax_is_pte_entry(entry)) ||
1536 (pe_size == PE_SIZE_PMD && !dax_is_pmd_entry(entry))) {
1537 put_unlocked_mapping_entry(mapping, index, entry);
1538 spin_unlock_irq(&mapping->tree_lock);
1539 trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
1540 VM_FAULT_NOPAGE);
1541 return VM_FAULT_NOPAGE;
1542 }
1543 radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
1544 entry = lock_slot(mapping, slot);
1545 spin_unlock_irq(&mapping->tree_lock);
1546 switch (pe_size) {
1547 case PE_SIZE_PTE:
1548 error = vm_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
1549 vmf_ret = dax_fault_return(error);
1550 break;
1551#ifdef CONFIG_FS_DAX_PMD
1552 case PE_SIZE_PMD:
1553 vmf_ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
1554 pfn, true);
1555 break;
1556#endif
1557 default:
1558 vmf_ret = VM_FAULT_FALLBACK;
1559 }
1560 put_locked_mapping_entry(mapping, index);
1561 trace_dax_insert_pfn_mkwrite(mapping->host, vmf, vmf_ret);
1562 return vmf_ret;
1563}
1564
1565/**
1566 * dax_finish_sync_fault - finish synchronous page fault
1567 * @vmf: The description of the fault
1568 * @pe_size: Size of entry to be inserted
1569 * @pfn: PFN to insert
1570 *
1571 * This function ensures that the file range touched by the page fault is
1572 * stored persistently on the media and handles inserting of appropriate page
1573 * table entry.
1574 */
1575int dax_finish_sync_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
1576 pfn_t pfn)
1577{
1578 int err;
1579 loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT;
1580 size_t len = 0;
1581
1582 if (pe_size == PE_SIZE_PTE)
1583 len = PAGE_SIZE;
1584 else if (pe_size == PE_SIZE_PMD)
1585 len = PMD_SIZE;
1586 else
1587 WARN_ON_ONCE(1);
1588 err = vfs_fsync_range(vmf->vma->vm_file, start, start + len - 1, 1);
1589 if (err)
1590 return VM_FAULT_SIGBUS;
1591 return dax_insert_pfn_mkwrite(vmf, pe_size, pfn);
1592}
1593EXPORT_SYMBOL_GPL(dax_finish_sync_fault);