blob: de622d4282a6507a9c4e4eb082ac6ff8286efb48 [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>
Ross Zwisler2765cfb2015-08-18 13:55:40 -060028#include <linux/pmem.h>
Matthew Wilcox289c6ae2015-02-16 15:58:59 -080029#include <linux/sched.h>
Ingo Molnarf361bf42017-02-03 23:47:37 +010030#include <linux/sched/signal.h>
Matthew Wilcoxd475c632015-02-16 15:58:56 -080031#include <linux/uio.h>
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -080032#include <linux/vmstat.h>
Dan Williams34c0fd52016-01-15 16:56:14 -080033#include <linux/pfn_t.h>
Dan Williams0e749e52016-01-15 16:55:53 -080034#include <linux/sizes.h>
Jan Kara4b4bb462016-12-14 15:07:53 -080035#include <linux/mmu_notifier.h>
Christoph Hellwiga254e562016-09-19 11:24:49 +100036#include <linux/iomap.h>
37#include "internal.h"
Matthew Wilcoxd475c632015-02-16 15:58:56 -080038
Ross Zwisler282a8e02017-02-22 15:39:50 -080039#define CREATE_TRACE_POINTS
40#include <trace/events/fs_dax.h>
41
Jan Karaac401cc2016-05-12 18:29:18 +020042/* We choose 4096 entries - same as per-zone page wait tables */
43#define DAX_WAIT_TABLE_BITS 12
44#define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
45
Ross Zwislerce95ab0f2016-11-08 11:31:44 +110046static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
Jan Karaac401cc2016-05-12 18:29:18 +020047
48static int __init init_dax_wait_table(void)
49{
50 int i;
51
52 for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++)
53 init_waitqueue_head(wait_table + i);
54 return 0;
55}
56fs_initcall(init_dax_wait_table);
57
Dan Williamsb2e0d162016-01-15 16:55:59 -080058static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
59{
60 struct request_queue *q = bdev->bd_queue;
61 long rc = -EIO;
62
Dan Williams7a9eb202016-06-03 18:06:47 -070063 dax->addr = ERR_PTR(-EIO);
Dan Williamsb2e0d162016-01-15 16:55:59 -080064 if (blk_queue_enter(q, true) != 0)
65 return rc;
66
67 rc = bdev_direct_access(bdev, dax);
68 if (rc < 0) {
Dan Williams7a9eb202016-06-03 18:06:47 -070069 dax->addr = ERR_PTR(rc);
Dan Williamsb2e0d162016-01-15 16:55:59 -080070 blk_queue_exit(q);
71 return rc;
72 }
73 return rc;
74}
75
76static void dax_unmap_atomic(struct block_device *bdev,
77 const struct blk_dax_ctl *dax)
78{
79 if (IS_ERR(dax->addr))
80 return;
81 blk_queue_exit(bdev->bd_queue);
82}
83
Ross Zwisler642261a2016-11-08 11:34:45 +110084static int dax_is_pmd_entry(void *entry)
85{
86 return (unsigned long)entry & RADIX_DAX_PMD;
87}
88
89static int dax_is_pte_entry(void *entry)
90{
91 return !((unsigned long)entry & RADIX_DAX_PMD);
92}
93
94static int dax_is_zero_entry(void *entry)
95{
96 return (unsigned long)entry & RADIX_DAX_HZP;
97}
98
99static int dax_is_empty_entry(void *entry)
100{
101 return (unsigned long)entry & RADIX_DAX_EMPTY;
102}
103
Dan Williamsd1a5f2b42016-01-28 20:25:31 -0800104struct page *read_dax_sector(struct block_device *bdev, sector_t n)
105{
106 struct page *page = alloc_pages(GFP_KERNEL, 0);
107 struct blk_dax_ctl dax = {
108 .size = PAGE_SIZE,
109 .sector = n & ~((((int) PAGE_SIZE) / 512) - 1),
110 };
111 long rc;
112
113 if (!page)
114 return ERR_PTR(-ENOMEM);
115
116 rc = dax_map_atomic(bdev, &dax);
117 if (rc < 0)
118 return ERR_PTR(rc);
119 memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE);
120 dax_unmap_atomic(bdev, &dax);
121 return page;
122}
123
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800124/*
Jan Karaac401cc2016-05-12 18:29:18 +0200125 * DAX radix tree locking
126 */
127struct exceptional_entry_key {
128 struct address_space *mapping;
Ross Zwisler63e95b52016-11-08 11:32:20 +1100129 pgoff_t entry_start;
Jan Karaac401cc2016-05-12 18:29:18 +0200130};
131
132struct wait_exceptional_entry_queue {
133 wait_queue_t wait;
134 struct exceptional_entry_key key;
135};
136
Ross Zwisler63e95b52016-11-08 11:32:20 +1100137static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
138 pgoff_t index, void *entry, struct exceptional_entry_key *key)
139{
140 unsigned long hash;
141
142 /*
143 * If 'entry' is a PMD, align the 'index' that we use for the wait
144 * queue to the start of that PMD. This ensures that all offsets in
145 * the range covered by the PMD map to the same bit lock.
146 */
Ross Zwisler642261a2016-11-08 11:34:45 +1100147 if (dax_is_pmd_entry(entry))
Ross Zwisler63e95b52016-11-08 11:32:20 +1100148 index &= ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1);
149
150 key->mapping = mapping;
151 key->entry_start = index;
152
153 hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS);
154 return wait_table + hash;
155}
156
Jan Karaac401cc2016-05-12 18:29:18 +0200157static int wake_exceptional_entry_func(wait_queue_t *wait, unsigned int mode,
158 int sync, void *keyp)
159{
160 struct exceptional_entry_key *key = keyp;
161 struct wait_exceptional_entry_queue *ewait =
162 container_of(wait, struct wait_exceptional_entry_queue, wait);
163
164 if (key->mapping != ewait->key.mapping ||
Ross Zwisler63e95b52016-11-08 11:32:20 +1100165 key->entry_start != ewait->key.entry_start)
Jan Karaac401cc2016-05-12 18:29:18 +0200166 return 0;
167 return autoremove_wake_function(wait, mode, sync, NULL);
168}
169
170/*
171 * Check whether the given slot is locked. The function must be called with
172 * mapping->tree_lock held
173 */
174static inline int slot_locked(struct address_space *mapping, void **slot)
175{
176 unsigned long entry = (unsigned long)
177 radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
178 return entry & RADIX_DAX_ENTRY_LOCK;
179}
180
181/*
182 * Mark the given slot is locked. The function must be called with
183 * mapping->tree_lock held
184 */
185static inline void *lock_slot(struct address_space *mapping, void **slot)
186{
187 unsigned long entry = (unsigned long)
188 radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
189
190 entry |= RADIX_DAX_ENTRY_LOCK;
Johannes Weiner6d75f362016-12-12 16:43:43 -0800191 radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200192 return (void *)entry;
193}
194
195/*
196 * Mark the given slot is unlocked. The function must be called with
197 * mapping->tree_lock held
198 */
199static inline void *unlock_slot(struct address_space *mapping, void **slot)
200{
201 unsigned long entry = (unsigned long)
202 radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
203
204 entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
Johannes Weiner6d75f362016-12-12 16:43:43 -0800205 radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200206 return (void *)entry;
207}
208
209/*
210 * Lookup entry in radix tree, wait for it to become unlocked if it is
211 * exceptional entry and return it. The caller must call
212 * put_unlocked_mapping_entry() when he decided not to lock the entry or
213 * put_locked_mapping_entry() when he locked the entry and now wants to
214 * unlock it.
215 *
216 * The function must be called with mapping->tree_lock held.
217 */
218static void *get_unlocked_mapping_entry(struct address_space *mapping,
219 pgoff_t index, void ***slotp)
220{
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100221 void *entry, **slot;
Jan Karaac401cc2016-05-12 18:29:18 +0200222 struct wait_exceptional_entry_queue ewait;
Ross Zwisler63e95b52016-11-08 11:32:20 +1100223 wait_queue_head_t *wq;
Jan Karaac401cc2016-05-12 18:29:18 +0200224
225 init_wait(&ewait.wait);
226 ewait.wait.func = wake_exceptional_entry_func;
Jan Karaac401cc2016-05-12 18:29:18 +0200227
228 for (;;) {
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100229 entry = __radix_tree_lookup(&mapping->page_tree, index, NULL,
Jan Karaac401cc2016-05-12 18:29:18 +0200230 &slot);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100231 if (!entry || !radix_tree_exceptional_entry(entry) ||
Jan Karaac401cc2016-05-12 18:29:18 +0200232 !slot_locked(mapping, slot)) {
233 if (slotp)
234 *slotp = slot;
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100235 return entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200236 }
Ross Zwisler63e95b52016-11-08 11:32:20 +1100237
238 wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
Jan Karaac401cc2016-05-12 18:29:18 +0200239 prepare_to_wait_exclusive(wq, &ewait.wait,
240 TASK_UNINTERRUPTIBLE);
241 spin_unlock_irq(&mapping->tree_lock);
242 schedule();
243 finish_wait(wq, &ewait.wait);
244 spin_lock_irq(&mapping->tree_lock);
245 }
246}
247
Jan Karab1aa8122016-12-14 15:07:24 -0800248static void dax_unlock_mapping_entry(struct address_space *mapping,
249 pgoff_t index)
250{
251 void *entry, **slot;
252
253 spin_lock_irq(&mapping->tree_lock);
254 entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
255 if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
256 !slot_locked(mapping, slot))) {
257 spin_unlock_irq(&mapping->tree_lock);
258 return;
259 }
260 unlock_slot(mapping, slot);
261 spin_unlock_irq(&mapping->tree_lock);
262 dax_wake_mapping_entry_waiter(mapping, index, entry, false);
263}
264
Jan Karaac401cc2016-05-12 18:29:18 +0200265static void put_locked_mapping_entry(struct address_space *mapping,
266 pgoff_t index, void *entry)
267{
268 if (!radix_tree_exceptional_entry(entry)) {
269 unlock_page(entry);
270 put_page(entry);
271 } else {
Jan Karabc2466e2016-05-12 18:29:19 +0200272 dax_unlock_mapping_entry(mapping, index);
Jan Karaac401cc2016-05-12 18:29:18 +0200273 }
274}
275
276/*
277 * Called when we are done with radix tree entry we looked up via
278 * get_unlocked_mapping_entry() and which we didn't lock in the end.
279 */
280static void put_unlocked_mapping_entry(struct address_space *mapping,
281 pgoff_t index, void *entry)
282{
283 if (!radix_tree_exceptional_entry(entry))
284 return;
285
286 /* We have to wake up next waiter for the radix tree entry lock */
Ross Zwisler422476c2016-11-08 11:33:44 +1100287 dax_wake_mapping_entry_waiter(mapping, index, entry, false);
288}
289
Jan Karaac401cc2016-05-12 18:29:18 +0200290/*
291 * Find radix tree entry at given index. If it points to a page, return with
292 * the page locked. If it points to the exceptional entry, return with the
293 * radix tree entry locked. If the radix tree doesn't contain given index,
294 * create empty exceptional entry for the index and return with it locked.
295 *
Ross Zwisler642261a2016-11-08 11:34:45 +1100296 * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
297 * either return that locked entry or will return an error. This error will
298 * happen if there are any 4k entries (either zero pages or DAX entries)
299 * within the 2MiB range that we are requesting.
300 *
301 * We always favor 4k entries over 2MiB entries. There isn't a flow where we
302 * evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB
303 * insertion will fail if it finds any 4k entries already in the tree, and a
304 * 4k insertion will cause an existing 2MiB entry to be unmapped and
305 * downgraded to 4k entries. This happens for both 2MiB huge zero pages as
306 * well as 2MiB empty entries.
307 *
308 * The exception to this downgrade path is for 2MiB DAX PMD entries that have
309 * real storage backing them. We will leave these real 2MiB DAX entries in
310 * the tree, and PTE writes will simply dirty the entire 2MiB DAX entry.
311 *
Jan Karaac401cc2016-05-12 18:29:18 +0200312 * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For
313 * persistent memory the benefit is doubtful. We can add that later if we can
314 * show it helps.
315 */
Ross Zwisler642261a2016-11-08 11:34:45 +1100316static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
317 unsigned long size_flag)
Jan Karaac401cc2016-05-12 18:29:18 +0200318{
Ross Zwisler642261a2016-11-08 11:34:45 +1100319 bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100320 void *entry, **slot;
Jan Karaac401cc2016-05-12 18:29:18 +0200321
322restart:
323 spin_lock_irq(&mapping->tree_lock);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100324 entry = get_unlocked_mapping_entry(mapping, index, &slot);
Ross Zwisler642261a2016-11-08 11:34:45 +1100325
326 if (entry) {
327 if (size_flag & RADIX_DAX_PMD) {
328 if (!radix_tree_exceptional_entry(entry) ||
329 dax_is_pte_entry(entry)) {
330 put_unlocked_mapping_entry(mapping, index,
331 entry);
332 entry = ERR_PTR(-EEXIST);
333 goto out_unlock;
334 }
335 } else { /* trying to grab a PTE entry */
336 if (radix_tree_exceptional_entry(entry) &&
337 dax_is_pmd_entry(entry) &&
338 (dax_is_zero_entry(entry) ||
339 dax_is_empty_entry(entry))) {
340 pmd_downgrade = true;
341 }
342 }
343 }
344
Jan Karaac401cc2016-05-12 18:29:18 +0200345 /* No entry for given index? Make sure radix tree is big enough. */
Ross Zwisler642261a2016-11-08 11:34:45 +1100346 if (!entry || pmd_downgrade) {
Jan Karaac401cc2016-05-12 18:29:18 +0200347 int err;
348
Ross Zwisler642261a2016-11-08 11:34:45 +1100349 if (pmd_downgrade) {
350 /*
351 * Make sure 'entry' remains valid while we drop
352 * mapping->tree_lock.
353 */
354 entry = lock_slot(mapping, slot);
355 }
356
Jan Karaac401cc2016-05-12 18:29:18 +0200357 spin_unlock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100358 /*
359 * Besides huge zero pages the only other thing that gets
360 * downgraded are empty entries which don't need to be
361 * unmapped.
362 */
363 if (pmd_downgrade && dax_is_zero_entry(entry))
364 unmap_mapping_range(mapping,
365 (index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
366
Jan Kara0cb80b42016-12-12 21:34:12 -0500367 err = radix_tree_preload(
368 mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
369 if (err) {
370 if (pmd_downgrade)
371 put_locked_mapping_entry(mapping, index, entry);
372 return ERR_PTR(err);
373 }
Jan Karaac401cc2016-05-12 18:29:18 +0200374 spin_lock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100375
376 if (pmd_downgrade) {
377 radix_tree_delete(&mapping->page_tree, index);
378 mapping->nrexceptional--;
379 dax_wake_mapping_entry_waiter(mapping, index, entry,
380 true);
381 }
382
383 entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
384
385 err = __radix_tree_insert(&mapping->page_tree, index,
386 dax_radix_order(entry), entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200387 radix_tree_preload_end();
388 if (err) {
389 spin_unlock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100390 /*
391 * Someone already created the entry? This is a
392 * normal failure when inserting PMDs in a range
393 * that already contains PTEs. In that case we want
394 * to return -EEXIST immediately.
395 */
396 if (err == -EEXIST && !(size_flag & RADIX_DAX_PMD))
Jan Karaac401cc2016-05-12 18:29:18 +0200397 goto restart;
Ross Zwisler642261a2016-11-08 11:34:45 +1100398 /*
399 * Our insertion of a DAX PMD entry failed, most
400 * likely because it collided with a PTE sized entry
401 * at a different index in the PMD range. We haven't
402 * inserted anything into the radix tree and have no
403 * waiters to wake.
404 */
Jan Karaac401cc2016-05-12 18:29:18 +0200405 return ERR_PTR(err);
406 }
407 /* Good, we have inserted empty locked entry into the tree. */
408 mapping->nrexceptional++;
409 spin_unlock_irq(&mapping->tree_lock);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100410 return entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200411 }
412 /* Normal page in radix tree? */
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100413 if (!radix_tree_exceptional_entry(entry)) {
414 struct page *page = entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200415
416 get_page(page);
417 spin_unlock_irq(&mapping->tree_lock);
418 lock_page(page);
419 /* Page got truncated? Retry... */
420 if (unlikely(page->mapping != mapping)) {
421 unlock_page(page);
422 put_page(page);
423 goto restart;
424 }
425 return page;
426 }
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100427 entry = lock_slot(mapping, slot);
Ross Zwisler642261a2016-11-08 11:34:45 +1100428 out_unlock:
Jan Karaac401cc2016-05-12 18:29:18 +0200429 spin_unlock_irq(&mapping->tree_lock);
Ross Zwislere3ad61c2016-11-08 11:32:12 +1100430 return entry;
Jan Karaac401cc2016-05-12 18:29:18 +0200431}
432
Ross Zwisler63e95b52016-11-08 11:32:20 +1100433/*
434 * We do not necessarily hold the mapping->tree_lock when we call this
435 * function so it is possible that 'entry' is no longer a valid item in the
Ross Zwisler642261a2016-11-08 11:34:45 +1100436 * radix tree. This is okay because all we really need to do is to find the
437 * correct waitqueue where tasks might be waiting for that old 'entry' and
438 * wake them.
Ross Zwisler63e95b52016-11-08 11:32:20 +1100439 */
Jan Karaac401cc2016-05-12 18:29:18 +0200440void dax_wake_mapping_entry_waiter(struct address_space *mapping,
Ross Zwisler63e95b52016-11-08 11:32:20 +1100441 pgoff_t index, void *entry, bool wake_all)
Jan Karaac401cc2016-05-12 18:29:18 +0200442{
Ross Zwisler63e95b52016-11-08 11:32:20 +1100443 struct exceptional_entry_key key;
444 wait_queue_head_t *wq;
445
446 wq = dax_entry_waitqueue(mapping, index, entry, &key);
Jan Karaac401cc2016-05-12 18:29:18 +0200447
448 /*
449 * Checking for locked entry and prepare_to_wait_exclusive() happens
450 * under mapping->tree_lock, ditto for entry handling in our callers.
451 * So at this point all tasks that could have seen our entry locked
452 * must be in the waitqueue and the following check will see them.
453 */
Ross Zwisler63e95b52016-11-08 11:32:20 +1100454 if (waitqueue_active(wq))
Jan Karaac401cc2016-05-12 18:29:18 +0200455 __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
Jan Karaac401cc2016-05-12 18:29:18 +0200456}
457
Jan Karac6dcf522016-08-10 17:22:44 +0200458static int __dax_invalidate_mapping_entry(struct address_space *mapping,
459 pgoff_t index, bool trunc)
460{
461 int ret = 0;
462 void *entry;
463 struct radix_tree_root *page_tree = &mapping->page_tree;
464
465 spin_lock_irq(&mapping->tree_lock);
466 entry = get_unlocked_mapping_entry(mapping, index, NULL);
467 if (!entry || !radix_tree_exceptional_entry(entry))
468 goto out;
469 if (!trunc &&
470 (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
471 radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)))
472 goto out;
473 radix_tree_delete(page_tree, index);
474 mapping->nrexceptional--;
475 ret = 1;
476out:
477 put_unlocked_mapping_entry(mapping, index, entry);
478 spin_unlock_irq(&mapping->tree_lock);
479 return ret;
480}
Jan Karaac401cc2016-05-12 18:29:18 +0200481/*
482 * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
483 * entry to get unlocked before deleting it.
484 */
485int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
486{
Jan Karac6dcf522016-08-10 17:22:44 +0200487 int ret = __dax_invalidate_mapping_entry(mapping, index, true);
Jan Karaac401cc2016-05-12 18:29:18 +0200488
Jan Karaac401cc2016-05-12 18:29:18 +0200489 /*
490 * This gets called from truncate / punch_hole path. As such, the caller
491 * must hold locks protecting against concurrent modifications of the
492 * radix tree (usually fs-private i_mmap_sem for writing). Since the
493 * caller has seen exceptional entry for this index, we better find it
494 * at that index as well...
495 */
Jan Karac6dcf522016-08-10 17:22:44 +0200496 WARN_ON_ONCE(!ret);
497 return ret;
498}
Jan Karaac401cc2016-05-12 18:29:18 +0200499
Jan Karac6dcf522016-08-10 17:22:44 +0200500/*
501 * Invalidate exceptional DAX entry if easily possible. This handles DAX
502 * entries for invalidate_inode_pages() so we evict the entry only if we can
503 * do so without blocking.
504 */
505int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index)
506{
507 int ret = 0;
508 void *entry, **slot;
509 struct radix_tree_root *page_tree = &mapping->page_tree;
510
511 spin_lock_irq(&mapping->tree_lock);
512 entry = __radix_tree_lookup(page_tree, index, NULL, &slot);
513 if (!entry || !radix_tree_exceptional_entry(entry) ||
514 slot_locked(mapping, slot))
515 goto out;
516 if (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
517 radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
518 goto out;
519 radix_tree_delete(page_tree, index);
520 mapping->nrexceptional--;
521 ret = 1;
522out:
523 spin_unlock_irq(&mapping->tree_lock);
524 if (ret)
525 dax_wake_mapping_entry_waiter(mapping, index, entry, true);
526 return ret;
527}
528
529/*
530 * Invalidate exceptional DAX entry if it is clean.
531 */
532int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
533 pgoff_t index)
534{
535 return __dax_invalidate_mapping_entry(mapping, index, false);
Jan Karaac401cc2016-05-12 18:29:18 +0200536}
537
538/*
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800539 * The user has performed a load from a hole in the file. Allocating
540 * a new page in the file would cause excessive storage usage for
541 * workloads with sparse files. We allocate a page cache page instead.
542 * We'll kick it out of the page cache if it's ever written to,
543 * otherwise it will simply fall out of the page cache under memory
544 * pressure without ever having been dirtied.
545 */
Jan Karaf449b932016-10-19 14:48:38 +0200546static int dax_load_hole(struct address_space *mapping, void **entry,
Jan Karaac401cc2016-05-12 18:29:18 +0200547 struct vm_fault *vmf)
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800548{
Jan Karaac401cc2016-05-12 18:29:18 +0200549 struct page *page;
Jan Karaf449b932016-10-19 14:48:38 +0200550 int ret;
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800551
Jan Karaac401cc2016-05-12 18:29:18 +0200552 /* Hole page already exists? Return it... */
Jan Karaf449b932016-10-19 14:48:38 +0200553 if (!radix_tree_exceptional_entry(*entry)) {
554 page = *entry;
555 goto out;
Jan Karaac401cc2016-05-12 18:29:18 +0200556 }
557
558 /* This will replace locked radix tree entry with a hole page */
559 page = find_or_create_page(mapping, vmf->pgoff,
560 vmf->gfp_mask | __GFP_ZERO);
Jan Karab1aa8122016-12-14 15:07:24 -0800561 if (!page)
Jan Karaac401cc2016-05-12 18:29:18 +0200562 return VM_FAULT_OOM;
Jan Karaf449b932016-10-19 14:48:38 +0200563 out:
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800564 vmf->page = page;
Jan Karaf449b932016-10-19 14:48:38 +0200565 ret = finish_fault(vmf);
566 vmf->page = NULL;
567 *entry = page;
568 if (!ret) {
569 /* Grab reference for PTE that is now referencing the page */
570 get_page(page);
571 return VM_FAULT_NOPAGE;
572 }
573 return ret;
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800574}
575
Christoph Hellwigb0d5e822016-09-19 11:24:49 +1000576static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size,
577 struct page *to, unsigned long vaddr)
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800578{
Dan Williamsb2e0d162016-01-15 16:55:59 -0800579 struct blk_dax_ctl dax = {
Christoph Hellwigb0d5e822016-09-19 11:24:49 +1000580 .sector = sector,
581 .size = size,
Dan Williamsb2e0d162016-01-15 16:55:59 -0800582 };
Ross Zwislere2e05392015-08-18 13:55:41 -0600583 void *vto;
584
Dan Williamsb2e0d162016-01-15 16:55:59 -0800585 if (dax_map_atomic(bdev, &dax) < 0)
586 return PTR_ERR(dax.addr);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800587 vto = kmap_atomic(to);
Dan Williamsb2e0d162016-01-15 16:55:59 -0800588 copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800589 kunmap_atomic(vto);
Dan Williamsb2e0d162016-01-15 16:55:59 -0800590 dax_unmap_atomic(bdev, &dax);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800591 return 0;
592}
593
Ross Zwisler642261a2016-11-08 11:34:45 +1100594/*
595 * By this point grab_mapping_entry() has ensured that we have a locked entry
596 * of the appropriate size so we don't have to worry about downgrading PMDs to
597 * PTEs. If we happen to be trying to insert a PTE and there is a PMD
598 * already in the tree, we will skip the insertion and just dirty the PMD as
599 * appropriate.
600 */
Jan Karaac401cc2016-05-12 18:29:18 +0200601static void *dax_insert_mapping_entry(struct address_space *mapping,
602 struct vm_fault *vmf,
Ross Zwisler642261a2016-11-08 11:34:45 +1100603 void *entry, sector_t sector,
604 unsigned long flags)
Ross Zwisler9973c982016-01-22 15:10:47 -0800605{
606 struct radix_tree_root *page_tree = &mapping->page_tree;
Jan Karaac401cc2016-05-12 18:29:18 +0200607 int error = 0;
608 bool hole_fill = false;
609 void *new_entry;
610 pgoff_t index = vmf->pgoff;
Ross Zwisler9973c982016-01-22 15:10:47 -0800611
Jan Karaac401cc2016-05-12 18:29:18 +0200612 if (vmf->flags & FAULT_FLAG_WRITE)
Dmitry Monakhovd2b2a282016-02-05 15:36:55 -0800613 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Ross Zwisler9973c982016-01-22 15:10:47 -0800614
Jan Karaac401cc2016-05-12 18:29:18 +0200615 /* Replacing hole page with block mapping? */
616 if (!radix_tree_exceptional_entry(entry)) {
617 hole_fill = true;
618 /*
619 * Unmap the page now before we remove it from page cache below.
620 * The page is locked so it cannot be faulted in again.
621 */
622 unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
623 PAGE_SIZE, 0);
624 error = radix_tree_preload(vmf->gfp_mask & ~__GFP_HIGHMEM);
625 if (error)
626 return ERR_PTR(error);
Ross Zwisler642261a2016-11-08 11:34:45 +1100627 } else if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_HZP)) {
628 /* replacing huge zero page with PMD block mapping */
629 unmap_mapping_range(mapping,
630 (vmf->pgoff << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
Ross Zwisler9973c982016-01-22 15:10:47 -0800631 }
632
Jan Karaac401cc2016-05-12 18:29:18 +0200633 spin_lock_irq(&mapping->tree_lock);
Ross Zwisler642261a2016-11-08 11:34:45 +1100634 new_entry = dax_radix_locked_entry(sector, flags);
635
Jan Karaac401cc2016-05-12 18:29:18 +0200636 if (hole_fill) {
637 __delete_from_page_cache(entry, NULL);
638 /* Drop pagecache reference */
639 put_page(entry);
Ross Zwisler642261a2016-11-08 11:34:45 +1100640 error = __radix_tree_insert(page_tree, index,
641 dax_radix_order(new_entry), new_entry);
Jan Karaac401cc2016-05-12 18:29:18 +0200642 if (error) {
643 new_entry = ERR_PTR(error);
Ross Zwisler9973c982016-01-22 15:10:47 -0800644 goto unlock;
645 }
Jan Karaac401cc2016-05-12 18:29:18 +0200646 mapping->nrexceptional++;
Ross Zwisler642261a2016-11-08 11:34:45 +1100647 } else if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
648 /*
649 * Only swap our new entry into the radix tree if the current
650 * entry is a zero page or an empty entry. If a normal PTE or
651 * PMD entry is already in the tree, we leave it alone. This
652 * means that if we are trying to insert a PTE and the
653 * existing entry is a PMD, we will just leave the PMD in the
654 * tree and dirty it if necessary.
655 */
Johannes Weinerf7942432016-12-12 16:43:41 -0800656 struct radix_tree_node *node;
Jan Karaac401cc2016-05-12 18:29:18 +0200657 void **slot;
658 void *ret;
Ross Zwisler9973c982016-01-22 15:10:47 -0800659
Johannes Weinerf7942432016-12-12 16:43:41 -0800660 ret = __radix_tree_lookup(page_tree, index, &node, &slot);
Jan Karaac401cc2016-05-12 18:29:18 +0200661 WARN_ON_ONCE(ret != entry);
Johannes Weiner4d693d02016-12-12 16:43:49 -0800662 __radix_tree_replace(page_tree, node, slot,
663 new_entry, NULL, NULL);
Ross Zwisler9973c982016-01-22 15:10:47 -0800664 }
Jan Karaac401cc2016-05-12 18:29:18 +0200665 if (vmf->flags & FAULT_FLAG_WRITE)
Ross Zwisler9973c982016-01-22 15:10:47 -0800666 radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
667 unlock:
668 spin_unlock_irq(&mapping->tree_lock);
Jan Karaac401cc2016-05-12 18:29:18 +0200669 if (hole_fill) {
670 radix_tree_preload_end();
671 /*
672 * We don't need hole page anymore, it has been replaced with
673 * locked radix tree entry now.
674 */
675 if (mapping->a_ops->freepage)
676 mapping->a_ops->freepage(entry);
677 unlock_page(entry);
678 put_page(entry);
679 }
680 return new_entry;
Ross Zwisler9973c982016-01-22 15:10:47 -0800681}
682
Jan Kara4b4bb462016-12-14 15:07:53 -0800683static inline unsigned long
684pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
685{
686 unsigned long address;
687
688 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
689 VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
690 return address;
691}
692
693/* Walk all mappings of a given index of a file and writeprotect them */
694static void dax_mapping_entry_mkclean(struct address_space *mapping,
695 pgoff_t index, unsigned long pfn)
696{
697 struct vm_area_struct *vma;
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800698 pte_t pte, *ptep = NULL;
699 pmd_t *pmdp = NULL;
Jan Kara4b4bb462016-12-14 15:07:53 -0800700 spinlock_t *ptl;
701 bool changed;
702
703 i_mmap_lock_read(mapping);
704 vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
705 unsigned long address;
706
707 cond_resched();
708
709 if (!(vma->vm_flags & VM_SHARED))
710 continue;
711
712 address = pgoff_address(index, vma);
713 changed = false;
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800714 if (follow_pte_pmd(vma->vm_mm, address, &ptep, &pmdp, &ptl))
Jan Kara4b4bb462016-12-14 15:07:53 -0800715 continue;
Jan Kara4b4bb462016-12-14 15:07:53 -0800716
Ross Zwislerf729c8c2017-01-10 16:57:24 -0800717 if (pmdp) {
718#ifdef CONFIG_FS_DAX_PMD
719 pmd_t pmd;
720
721 if (pfn != pmd_pfn(*pmdp))
722 goto unlock_pmd;
723 if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))
724 goto unlock_pmd;
725
726 flush_cache_page(vma, address, pfn);
727 pmd = pmdp_huge_clear_flush(vma, address, pmdp);
728 pmd = pmd_wrprotect(pmd);
729 pmd = pmd_mkclean(pmd);
730 set_pmd_at(vma->vm_mm, address, pmdp, pmd);
731 changed = true;
732unlock_pmd:
733 spin_unlock(ptl);
734#endif
735 } else {
736 if (pfn != pte_pfn(*ptep))
737 goto unlock_pte;
738 if (!pte_dirty(*ptep) && !pte_write(*ptep))
739 goto unlock_pte;
740
741 flush_cache_page(vma, address, pfn);
742 pte = ptep_clear_flush(vma, address, ptep);
743 pte = pte_wrprotect(pte);
744 pte = pte_mkclean(pte);
745 set_pte_at(vma->vm_mm, address, ptep, pte);
746 changed = true;
747unlock_pte:
748 pte_unmap_unlock(ptep, ptl);
749 }
Jan Kara4b4bb462016-12-14 15:07:53 -0800750
751 if (changed)
752 mmu_notifier_invalidate_page(vma->vm_mm, address);
753 }
754 i_mmap_unlock_read(mapping);
755}
756
Ross Zwisler9973c982016-01-22 15:10:47 -0800757static int dax_writeback_one(struct block_device *bdev,
758 struct address_space *mapping, pgoff_t index, void *entry)
759{
760 struct radix_tree_root *page_tree = &mapping->page_tree;
Ross Zwisler9973c982016-01-22 15:10:47 -0800761 struct blk_dax_ctl dax;
Jan Karaa6abc2c2016-12-14 15:07:47 -0800762 void *entry2, **slot;
Ross Zwisler9973c982016-01-22 15:10:47 -0800763 int ret = 0;
764
Ross Zwisler9973c982016-01-22 15:10:47 -0800765 /*
Jan Karaa6abc2c2016-12-14 15:07:47 -0800766 * A page got tagged dirty in DAX mapping? Something is seriously
767 * wrong.
Ross Zwisler9973c982016-01-22 15:10:47 -0800768 */
Jan Karaa6abc2c2016-12-14 15:07:47 -0800769 if (WARN_ON(!radix_tree_exceptional_entry(entry)))
770 return -EIO;
Ross Zwisler9973c982016-01-22 15:10:47 -0800771
Jan Karaa6abc2c2016-12-14 15:07:47 -0800772 spin_lock_irq(&mapping->tree_lock);
773 entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
774 /* Entry got punched out / reallocated? */
775 if (!entry2 || !radix_tree_exceptional_entry(entry2))
776 goto put_unlocked;
777 /*
778 * Entry got reallocated elsewhere? No need to writeback. We have to
779 * compare sectors as we must not bail out due to difference in lockbit
780 * or entry type.
781 */
782 if (dax_radix_sector(entry2) != dax_radix_sector(entry))
783 goto put_unlocked;
Ross Zwisler642261a2016-11-08 11:34:45 +1100784 if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
785 dax_is_zero_entry(entry))) {
Ross Zwisler9973c982016-01-22 15:10:47 -0800786 ret = -EIO;
Jan Karaa6abc2c2016-12-14 15:07:47 -0800787 goto put_unlocked;
Ross Zwisler9973c982016-01-22 15:10:47 -0800788 }
789
Jan Karaa6abc2c2016-12-14 15:07:47 -0800790 /* Another fsync thread may have already written back this entry */
791 if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
792 goto put_unlocked;
793 /* Lock the entry to serialize with page faults */
794 entry = lock_slot(mapping, slot);
795 /*
796 * We can clear the tag now but we have to be careful so that concurrent
797 * dax_writeback_one() calls for the same index cannot finish before we
798 * actually flush the caches. This is achieved as the calls will look
799 * at the entry only under tree_lock and once they do that they will
800 * see the entry locked and wait for it to unlock.
801 */
802 radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
803 spin_unlock_irq(&mapping->tree_lock);
804
Ross Zwisler642261a2016-11-08 11:34:45 +1100805 /*
806 * Even if dax_writeback_mapping_range() was given a wbc->range_start
807 * in the middle of a PMD, the 'index' we are given will be aligned to
808 * the start index of the PMD, as will the sector we pull from
809 * 'entry'. This allows us to flush for PMD_SIZE and not have to
810 * worry about partial PMD writebacks.
811 */
812 dax.sector = dax_radix_sector(entry);
813 dax.size = PAGE_SIZE << dax_radix_order(entry);
Ross Zwisler9973c982016-01-22 15:10:47 -0800814
815 /*
816 * We cannot hold tree_lock while calling dax_map_atomic() because it
817 * eventually calls cond_resched().
818 */
819 ret = dax_map_atomic(bdev, &dax);
Jan Karaa6abc2c2016-12-14 15:07:47 -0800820 if (ret < 0) {
821 put_locked_mapping_entry(mapping, index, entry);
Ross Zwisler9973c982016-01-22 15:10:47 -0800822 return ret;
Jan Karaa6abc2c2016-12-14 15:07:47 -0800823 }
Ross Zwisler9973c982016-01-22 15:10:47 -0800824
825 if (WARN_ON_ONCE(ret < dax.size)) {
826 ret = -EIO;
827 goto unmap;
828 }
829
Jan Kara4b4bb462016-12-14 15:07:53 -0800830 dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn));
Ross Zwisler9973c982016-01-22 15:10:47 -0800831 wb_cache_pmem(dax.addr, dax.size);
Jan Kara4b4bb462016-12-14 15:07:53 -0800832 /*
833 * After we have flushed the cache, we can clear the dirty tag. There
834 * cannot be new dirty data in the pfn after the flush has completed as
835 * the pfn mappings are writeprotected and fault waits for mapping
836 * entry lock.
837 */
838 spin_lock_irq(&mapping->tree_lock);
839 radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
840 spin_unlock_irq(&mapping->tree_lock);
Ross Zwisler9973c982016-01-22 15:10:47 -0800841 unmap:
842 dax_unmap_atomic(bdev, &dax);
Jan Karaa6abc2c2016-12-14 15:07:47 -0800843 put_locked_mapping_entry(mapping, index, entry);
Ross Zwisler9973c982016-01-22 15:10:47 -0800844 return ret;
845
Jan Karaa6abc2c2016-12-14 15:07:47 -0800846 put_unlocked:
847 put_unlocked_mapping_entry(mapping, index, entry2);
Ross Zwisler9973c982016-01-22 15:10:47 -0800848 spin_unlock_irq(&mapping->tree_lock);
849 return ret;
850}
851
852/*
853 * Flush the mapping to the persistent domain within the byte range of [start,
854 * end]. This is required by data integrity operations to ensure file data is
855 * on persistent storage prior to completion of the operation.
856 */
Ross Zwisler7f6d5b52016-02-26 15:19:55 -0800857int dax_writeback_mapping_range(struct address_space *mapping,
858 struct block_device *bdev, struct writeback_control *wbc)
Ross Zwisler9973c982016-01-22 15:10:47 -0800859{
860 struct inode *inode = mapping->host;
Ross Zwisler642261a2016-11-08 11:34:45 +1100861 pgoff_t start_index, end_index;
Ross Zwisler9973c982016-01-22 15:10:47 -0800862 pgoff_t indices[PAGEVEC_SIZE];
863 struct pagevec pvec;
864 bool done = false;
865 int i, ret = 0;
Ross Zwisler9973c982016-01-22 15:10:47 -0800866
867 if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
868 return -EIO;
869
Ross Zwisler7f6d5b52016-02-26 15:19:55 -0800870 if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
871 return 0;
872
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300873 start_index = wbc->range_start >> PAGE_SHIFT;
874 end_index = wbc->range_end >> PAGE_SHIFT;
Ross Zwisler9973c982016-01-22 15:10:47 -0800875
876 tag_pages_for_writeback(mapping, start_index, end_index);
877
878 pagevec_init(&pvec, 0);
879 while (!done) {
880 pvec.nr = find_get_entries_tag(mapping, start_index,
881 PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
882 pvec.pages, indices);
883
884 if (pvec.nr == 0)
885 break;
886
887 for (i = 0; i < pvec.nr; i++) {
888 if (indices[i] > end_index) {
889 done = true;
890 break;
891 }
892
893 ret = dax_writeback_one(bdev, mapping, indices[i],
894 pvec.pages[i]);
895 if (ret < 0)
896 return ret;
897 }
898 }
Ross Zwisler9973c982016-01-22 15:10:47 -0800899 return 0;
900}
901EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
902
Jan Karaac401cc2016-05-12 18:29:18 +0200903static int dax_insert_mapping(struct address_space *mapping,
Christoph Hellwig1aaba092016-09-19 11:24:49 +1000904 struct block_device *bdev, sector_t sector, size_t size,
905 void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf)
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800906{
Jan Kara1a29d852016-12-14 15:07:01 -0800907 unsigned long vaddr = vmf->address;
Dan Williamsb2e0d162016-01-15 16:55:59 -0800908 struct blk_dax_ctl dax = {
Christoph Hellwig1aaba092016-09-19 11:24:49 +1000909 .sector = sector,
910 .size = size,
Dan Williamsb2e0d162016-01-15 16:55:59 -0800911 };
Jan Karaac401cc2016-05-12 18:29:18 +0200912 void *ret;
913 void *entry = *entryp;
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800914
Jan Kara4d9a2c82016-05-12 18:29:20 +0200915 if (dax_map_atomic(bdev, &dax) < 0)
916 return PTR_ERR(dax.addr);
Dan Williamsb2e0d162016-01-15 16:55:59 -0800917 dax_unmap_atomic(bdev, &dax);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800918
Ross Zwisler642261a2016-11-08 11:34:45 +1100919 ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector, 0);
Jan Kara4d9a2c82016-05-12 18:29:20 +0200920 if (IS_ERR(ret))
921 return PTR_ERR(ret);
Jan Karaac401cc2016-05-12 18:29:18 +0200922 *entryp = ret;
Ross Zwisler9973c982016-01-22 15:10:47 -0800923
Jan Kara4d9a2c82016-05-12 18:29:20 +0200924 return vm_insert_mixed(vma, vaddr, dax.pfn);
Matthew Wilcoxf7ca90b2015-02-16 15:59:02 -0800925}
926
Dave Chinnerce5c5d52015-06-04 09:18:18 +1000927/**
Boaz Harrosh0e3b2102015-04-15 16:15:14 -0700928 * dax_pfn_mkwrite - handle first write to DAX page
Boaz Harrosh0e3b2102015-04-15 16:15:14 -0700929 * @vmf: The description of the fault
Boaz Harrosh0e3b2102015-04-15 16:15:14 -0700930 */
Dave Jiang11bac802017-02-24 14:56:41 -0800931int dax_pfn_mkwrite(struct vm_fault *vmf)
Boaz Harrosh0e3b2102015-04-15 16:15:14 -0700932{
Dave Jiang11bac802017-02-24 14:56:41 -0800933 struct file *file = vmf->vma->vm_file;
Jan Karaac401cc2016-05-12 18:29:18 +0200934 struct address_space *mapping = file->f_mapping;
Jan Kara2f89dc12016-12-14 15:07:50 -0800935 void *entry, **slot;
Jan Karaac401cc2016-05-12 18:29:18 +0200936 pgoff_t index = vmf->pgoff;
Boaz Harrosh0e3b2102015-04-15 16:15:14 -0700937
Jan Karaac401cc2016-05-12 18:29:18 +0200938 spin_lock_irq(&mapping->tree_lock);
Jan Kara2f89dc12016-12-14 15:07:50 -0800939 entry = get_unlocked_mapping_entry(mapping, index, &slot);
940 if (!entry || !radix_tree_exceptional_entry(entry)) {
941 if (entry)
942 put_unlocked_mapping_entry(mapping, index, entry);
943 spin_unlock_irq(&mapping->tree_lock);
944 return VM_FAULT_NOPAGE;
945 }
Jan Karaac401cc2016-05-12 18:29:18 +0200946 radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
Jan Kara2f89dc12016-12-14 15:07:50 -0800947 entry = lock_slot(mapping, slot);
Jan Karaac401cc2016-05-12 18:29:18 +0200948 spin_unlock_irq(&mapping->tree_lock);
Jan Kara2f89dc12016-12-14 15:07:50 -0800949 /*
950 * If we race with somebody updating the PTE and finish_mkwrite_fault()
951 * fails, we don't care. We need to return VM_FAULT_NOPAGE and retry
952 * the fault in either case.
953 */
954 finish_mkwrite_fault(vmf);
955 put_locked_mapping_entry(mapping, index, entry);
Boaz Harrosh0e3b2102015-04-15 16:15:14 -0700956 return VM_FAULT_NOPAGE;
957}
958EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
959
Vishal Verma4b0228f2016-04-21 15:13:46 -0400960static bool dax_range_is_aligned(struct block_device *bdev,
961 unsigned int offset, unsigned int length)
962{
963 unsigned short sector_size = bdev_logical_block_size(bdev);
964
965 if (!IS_ALIGNED(offset, sector_size))
966 return false;
967 if (!IS_ALIGNED(length, sector_size))
968 return false;
969
970 return true;
971}
972
Christoph Hellwig679c8bd2016-05-09 10:47:04 +0200973int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
974 unsigned int offset, unsigned int length)
975{
976 struct blk_dax_ctl dax = {
977 .sector = sector,
978 .size = PAGE_SIZE,
979 };
980
Vishal Verma4b0228f2016-04-21 15:13:46 -0400981 if (dax_range_is_aligned(bdev, offset, length)) {
982 sector_t start_sector = dax.sector + (offset >> 9);
983
984 return blkdev_issue_zeroout(bdev, start_sector,
985 length >> 9, GFP_NOFS, true);
986 } else {
987 if (dax_map_atomic(bdev, &dax) < 0)
988 return PTR_ERR(dax.addr);
989 clear_pmem(dax.addr + offset, length);
Vishal Verma4b0228f2016-04-21 15:13:46 -0400990 dax_unmap_atomic(bdev, &dax);
991 }
Christoph Hellwig679c8bd2016-05-09 10:47:04 +0200992 return 0;
993}
994EXPORT_SYMBOL_GPL(__dax_zero_page_range);
995
Ross Zwisler333ccc92016-11-08 11:33:09 +1100996static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
997{
998 return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
999}
1000
Christoph Hellwiga254e562016-09-19 11:24:49 +10001001static loff_t
Ross Zwisler11c59c92016-11-08 11:32:46 +11001002dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
Christoph Hellwiga254e562016-09-19 11:24:49 +10001003 struct iomap *iomap)
1004{
1005 struct iov_iter *iter = data;
1006 loff_t end = pos + length, done = 0;
1007 ssize_t ret = 0;
1008
1009 if (iov_iter_rw(iter) == READ) {
1010 end = min(end, i_size_read(inode));
1011 if (pos >= end)
1012 return 0;
1013
1014 if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
1015 return iov_iter_zero(min(length, end - pos), iter);
1016 }
1017
1018 if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
1019 return -EIO;
1020
Jan Karae3fce682016-08-10 17:10:28 +02001021 /*
1022 * Write can allocate block for an area which has a hole page mapped
1023 * into page tables. We have to tear down these mappings so that data
1024 * written by write(2) is visible in mmap.
1025 */
1026 if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) {
1027 invalidate_inode_pages2_range(inode->i_mapping,
1028 pos >> PAGE_SHIFT,
1029 (end - 1) >> PAGE_SHIFT);
1030 }
1031
Christoph Hellwiga254e562016-09-19 11:24:49 +10001032 while (pos < end) {
1033 unsigned offset = pos & (PAGE_SIZE - 1);
1034 struct blk_dax_ctl dax = { 0 };
1035 ssize_t map_len;
1036
Michal Hockod1908f52017-02-03 13:13:26 -08001037 if (fatal_signal_pending(current)) {
1038 ret = -EINTR;
1039 break;
1040 }
1041
Ross Zwisler333ccc92016-11-08 11:33:09 +11001042 dax.sector = dax_iomap_sector(iomap, pos);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001043 dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
1044 map_len = dax_map_atomic(iomap->bdev, &dax);
1045 if (map_len < 0) {
1046 ret = map_len;
1047 break;
1048 }
1049
1050 dax.addr += offset;
1051 map_len -= offset;
1052 if (map_len > end - pos)
1053 map_len = end - pos;
1054
1055 if (iov_iter_rw(iter) == WRITE)
1056 map_len = copy_from_iter_pmem(dax.addr, map_len, iter);
1057 else
1058 map_len = copy_to_iter(dax.addr, map_len, iter);
1059 dax_unmap_atomic(iomap->bdev, &dax);
1060 if (map_len <= 0) {
1061 ret = map_len ? map_len : -EFAULT;
1062 break;
1063 }
1064
1065 pos += map_len;
1066 length -= map_len;
1067 done += map_len;
1068 }
1069
1070 return done ? done : ret;
1071}
1072
1073/**
Ross Zwisler11c59c92016-11-08 11:32:46 +11001074 * dax_iomap_rw - Perform I/O to a DAX file
Christoph Hellwiga254e562016-09-19 11:24:49 +10001075 * @iocb: The control block for this I/O
1076 * @iter: The addresses to do I/O from or to
1077 * @ops: iomap ops passed from the file system
1078 *
1079 * This function performs read and write operations to directly mapped
1080 * persistent memory. The callers needs to take care of read/write exclusion
1081 * and evicting any page cache pages in the region under I/O.
1082 */
1083ssize_t
Ross Zwisler11c59c92016-11-08 11:32:46 +11001084dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
Christoph Hellwig8ff6daa2017-01-27 23:20:26 -08001085 const struct iomap_ops *ops)
Christoph Hellwiga254e562016-09-19 11:24:49 +10001086{
1087 struct address_space *mapping = iocb->ki_filp->f_mapping;
1088 struct inode *inode = mapping->host;
1089 loff_t pos = iocb->ki_pos, ret = 0, done = 0;
1090 unsigned flags = 0;
1091
Christoph Hellwig168316d2017-02-08 14:43:13 -05001092 if (iov_iter_rw(iter) == WRITE) {
1093 lockdep_assert_held_exclusive(&inode->i_rwsem);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001094 flags |= IOMAP_WRITE;
Christoph Hellwig168316d2017-02-08 14:43:13 -05001095 } else {
1096 lockdep_assert_held(&inode->i_rwsem);
1097 }
Christoph Hellwiga254e562016-09-19 11:24:49 +10001098
Christoph Hellwiga254e562016-09-19 11:24:49 +10001099 while (iov_iter_count(iter)) {
1100 ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
Ross Zwisler11c59c92016-11-08 11:32:46 +11001101 iter, dax_iomap_actor);
Christoph Hellwiga254e562016-09-19 11:24:49 +10001102 if (ret <= 0)
1103 break;
1104 pos += ret;
1105 done += ret;
1106 }
1107
1108 iocb->ki_pos += done;
1109 return done ? done : ret;
1110}
Ross Zwisler11c59c92016-11-08 11:32:46 +11001111EXPORT_SYMBOL_GPL(dax_iomap_rw);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001112
Jan Kara9f141d62016-10-19 14:34:31 +02001113static int dax_fault_return(int error)
1114{
1115 if (error == 0)
1116 return VM_FAULT_NOPAGE;
1117 if (error == -ENOMEM)
1118 return VM_FAULT_OOM;
1119 return VM_FAULT_SIGBUS;
1120}
1121
Dave Jianga2d581672017-02-24 14:56:59 -08001122static int dax_iomap_pte_fault(struct vm_fault *vmf,
1123 const struct iomap_ops *ops)
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001124{
Dave Jiang11bac802017-02-24 14:56:41 -08001125 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001126 struct inode *inode = mapping->host;
Jan Kara1a29d852016-12-14 15:07:01 -08001127 unsigned long vaddr = vmf->address;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001128 loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
1129 sector_t sector;
1130 struct iomap iomap = { 0 };
Jan Kara9484ab12016-11-10 10:26:50 +11001131 unsigned flags = IOMAP_FAULT;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001132 int error, major = 0;
Jan Karab1aa8122016-12-14 15:07:24 -08001133 int vmf_ret = 0;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001134 void *entry;
1135
1136 /*
1137 * Check whether offset isn't beyond end of file now. Caller is supposed
1138 * to hold locks serializing us with truncate / punch hole so this is
1139 * a reliable test.
1140 */
1141 if (pos >= i_size_read(inode))
1142 return VM_FAULT_SIGBUS;
1143
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001144 if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
1145 flags |= IOMAP_WRITE;
1146
1147 /*
1148 * Note that we don't bother to use iomap_apply here: DAX required
1149 * the file system block size to be equal the page size, which means
1150 * that we never have to deal with more than a single extent here.
1151 */
1152 error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
1153 if (error)
Jan Kara9f141d62016-10-19 14:34:31 +02001154 return dax_fault_return(error);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001155 if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
Jan Kara9f141d62016-10-19 14:34:31 +02001156 vmf_ret = dax_fault_return(-EIO); /* fs corruption? */
1157 goto finish_iomap;
1158 }
1159
1160 entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
1161 if (IS_ERR(entry)) {
1162 vmf_ret = dax_fault_return(PTR_ERR(entry));
Ross Zwisler15502902016-11-08 11:33:26 +11001163 goto finish_iomap;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001164 }
1165
Ross Zwisler333ccc92016-11-08 11:33:09 +11001166 sector = dax_iomap_sector(&iomap, pos);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001167
1168 if (vmf->cow_page) {
1169 switch (iomap.type) {
1170 case IOMAP_HOLE:
1171 case IOMAP_UNWRITTEN:
1172 clear_user_highpage(vmf->cow_page, vaddr);
1173 break;
1174 case IOMAP_MAPPED:
1175 error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE,
1176 vmf->cow_page, vaddr);
1177 break;
1178 default:
1179 WARN_ON_ONCE(1);
1180 error = -EIO;
1181 break;
1182 }
1183
1184 if (error)
Jan Kara9f141d62016-10-19 14:34:31 +02001185 goto error_unlock_entry;
Jan Karab1aa8122016-12-14 15:07:24 -08001186
1187 __SetPageUptodate(vmf->cow_page);
1188 vmf_ret = finish_fault(vmf);
1189 if (!vmf_ret)
1190 vmf_ret = VM_FAULT_DONE_COW;
Jan Kara9f141d62016-10-19 14:34:31 +02001191 goto unlock_entry;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001192 }
1193
1194 switch (iomap.type) {
1195 case IOMAP_MAPPED:
1196 if (iomap.flags & IOMAP_F_NEW) {
1197 count_vm_event(PGMAJFAULT);
Dave Jiang11bac802017-02-24 14:56:41 -08001198 mem_cgroup_count_vm_event(vmf->vma->vm_mm, PGMAJFAULT);
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001199 major = VM_FAULT_MAJOR;
1200 }
1201 error = dax_insert_mapping(mapping, iomap.bdev, sector,
Dave Jiang11bac802017-02-24 14:56:41 -08001202 PAGE_SIZE, &entry, vmf->vma, vmf);
Jan Kara9f141d62016-10-19 14:34:31 +02001203 /* -EBUSY is fine, somebody else faulted on the same PTE */
1204 if (error == -EBUSY)
1205 error = 0;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001206 break;
1207 case IOMAP_UNWRITTEN:
1208 case IOMAP_HOLE:
Ross Zwisler15502902016-11-08 11:33:26 +11001209 if (!(vmf->flags & FAULT_FLAG_WRITE)) {
Jan Karaf449b932016-10-19 14:48:38 +02001210 vmf_ret = dax_load_hole(mapping, &entry, vmf);
Jan Kara9f141d62016-10-19 14:34:31 +02001211 goto unlock_entry;
Ross Zwisler15502902016-11-08 11:33:26 +11001212 }
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001213 /*FALLTHRU*/
1214 default:
1215 WARN_ON_ONCE(1);
1216 error = -EIO;
1217 break;
1218 }
1219
Jan Kara9f141d62016-10-19 14:34:31 +02001220 error_unlock_entry:
1221 vmf_ret = dax_fault_return(error) | major;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001222 unlock_entry:
Jan Karaf449b932016-10-19 14:48:38 +02001223 put_locked_mapping_entry(mapping, vmf->pgoff, entry);
Jan Kara9f141d62016-10-19 14:34:31 +02001224 finish_iomap:
1225 if (ops->iomap_end) {
1226 int copied = PAGE_SIZE;
1227
1228 if (vmf_ret & VM_FAULT_ERROR)
1229 copied = 0;
1230 /*
1231 * The fault is done by now and there's no way back (other
1232 * thread may be already happily using PTE we have installed).
1233 * Just ignore error from ->iomap_end since we cannot do much
1234 * with it.
1235 */
1236 ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
Ross Zwisler15502902016-11-08 11:33:26 +11001237 }
Jan Kara9f141d62016-10-19 14:34:31 +02001238 return vmf_ret;
Christoph Hellwiga7d73fe2016-09-19 11:24:50 +10001239}
Ross Zwisler642261a2016-11-08 11:34:45 +11001240
1241#ifdef CONFIG_FS_DAX_PMD
1242/*
1243 * The 'colour' (ie low bits) within a PMD of a page offset. This comes up
1244 * more often than one might expect in the below functions.
1245 */
1246#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
1247
Dave Jiangf4200392017-02-22 15:40:06 -08001248static int dax_pmd_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
1249 loff_t pos, void **entryp)
Ross Zwisler642261a2016-11-08 11:34:45 +11001250{
Dave Jiangf4200392017-02-22 15:40:06 -08001251 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
Ross Zwisler642261a2016-11-08 11:34:45 +11001252 struct block_device *bdev = iomap->bdev;
Ross Zwisler27a7ffa2017-02-22 15:40:00 -08001253 struct inode *inode = mapping->host;
Ross Zwisler642261a2016-11-08 11:34:45 +11001254 struct blk_dax_ctl dax = {
1255 .sector = dax_iomap_sector(iomap, pos),
1256 .size = PMD_SIZE,
1257 };
1258 long length = dax_map_atomic(bdev, &dax);
Ross Zwisler27a7ffa2017-02-22 15:40:00 -08001259 void *ret = NULL;
Ross Zwisler642261a2016-11-08 11:34:45 +11001260
1261 if (length < 0) /* dax_map_atomic() failed */
Ross Zwisler27a7ffa2017-02-22 15:40:00 -08001262 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001263 if (length < PMD_SIZE)
1264 goto unmap_fallback;
1265 if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)
1266 goto unmap_fallback;
1267 if (!pfn_t_devmap(dax.pfn))
1268 goto unmap_fallback;
1269
1270 dax_unmap_atomic(bdev, &dax);
1271
1272 ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector,
1273 RADIX_DAX_PMD);
1274 if (IS_ERR(ret))
Ross Zwisler27a7ffa2017-02-22 15:40:00 -08001275 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001276 *entryp = ret;
1277
Dave Jiangf4200392017-02-22 15:40:06 -08001278 trace_dax_pmd_insert_mapping(inode, vmf, length, dax.pfn, ret);
1279 return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
1280 dax.pfn, vmf->flags & FAULT_FLAG_WRITE);
Ross Zwisler642261a2016-11-08 11:34:45 +11001281
1282 unmap_fallback:
1283 dax_unmap_atomic(bdev, &dax);
Ross Zwisler27a7ffa2017-02-22 15:40:00 -08001284fallback:
Dave Jiangf4200392017-02-22 15:40:06 -08001285 trace_dax_pmd_insert_mapping_fallback(inode, vmf, length,
1286 dax.pfn, ret);
Ross Zwisler642261a2016-11-08 11:34:45 +11001287 return VM_FAULT_FALLBACK;
1288}
1289
Dave Jiangf4200392017-02-22 15:40:06 -08001290static int dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
1291 void **entryp)
Ross Zwisler642261a2016-11-08 11:34:45 +11001292{
Dave Jiangf4200392017-02-22 15:40:06 -08001293 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
1294 unsigned long pmd_addr = vmf->address & PMD_MASK;
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001295 struct inode *inode = mapping->host;
Ross Zwisler642261a2016-11-08 11:34:45 +11001296 struct page *zero_page;
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001297 void *ret = NULL;
Ross Zwisler642261a2016-11-08 11:34:45 +11001298 spinlock_t *ptl;
1299 pmd_t pmd_entry;
Ross Zwisler642261a2016-11-08 11:34:45 +11001300
Dave Jiangf4200392017-02-22 15:40:06 -08001301 zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm);
Ross Zwisler642261a2016-11-08 11:34:45 +11001302
1303 if (unlikely(!zero_page))
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001304 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001305
1306 ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0,
1307 RADIX_DAX_PMD | RADIX_DAX_HZP);
1308 if (IS_ERR(ret))
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001309 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001310 *entryp = ret;
1311
Dave Jiangf4200392017-02-22 15:40:06 -08001312 ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1313 if (!pmd_none(*(vmf->pmd))) {
Ross Zwisler642261a2016-11-08 11:34:45 +11001314 spin_unlock(ptl);
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001315 goto fallback;
Ross Zwisler642261a2016-11-08 11:34:45 +11001316 }
1317
Dave Jiangf4200392017-02-22 15:40:06 -08001318 pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
Ross Zwisler642261a2016-11-08 11:34:45 +11001319 pmd_entry = pmd_mkhuge(pmd_entry);
Dave Jiangf4200392017-02-22 15:40:06 -08001320 set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
Ross Zwisler642261a2016-11-08 11:34:45 +11001321 spin_unlock(ptl);
Dave Jiangf4200392017-02-22 15:40:06 -08001322 trace_dax_pmd_load_hole(inode, vmf, zero_page, ret);
Ross Zwisler642261a2016-11-08 11:34:45 +11001323 return VM_FAULT_NOPAGE;
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001324
1325fallback:
Dave Jiangf4200392017-02-22 15:40:06 -08001326 trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, ret);
Ross Zwisler653b2ea2017-02-22 15:39:57 -08001327 return VM_FAULT_FALLBACK;
Ross Zwisler642261a2016-11-08 11:34:45 +11001328}
1329
Dave Jianga2d581672017-02-24 14:56:59 -08001330static int dax_iomap_pmd_fault(struct vm_fault *vmf,
1331 const struct iomap_ops *ops)
Ross Zwisler642261a2016-11-08 11:34:45 +11001332{
Dave Jiangf4200392017-02-22 15:40:06 -08001333 struct vm_area_struct *vma = vmf->vma;
Ross Zwisler642261a2016-11-08 11:34:45 +11001334 struct address_space *mapping = vma->vm_file->f_mapping;
Dave Jiangd8a849e2017-02-22 15:40:03 -08001335 unsigned long pmd_addr = vmf->address & PMD_MASK;
1336 bool write = vmf->flags & FAULT_FLAG_WRITE;
Jan Kara9484ab12016-11-10 10:26:50 +11001337 unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
Ross Zwisler642261a2016-11-08 11:34:45 +11001338 struct inode *inode = mapping->host;
1339 int result = VM_FAULT_FALLBACK;
1340 struct iomap iomap = { 0 };
1341 pgoff_t max_pgoff, pgoff;
Ross Zwisler642261a2016-11-08 11:34:45 +11001342 void *entry;
1343 loff_t pos;
1344 int error;
1345
Ross Zwisler282a8e02017-02-22 15:39:50 -08001346 /*
1347 * Check whether offset isn't beyond end of file now. Caller is
1348 * supposed to hold locks serializing us with truncate / punch hole so
1349 * this is a reliable test.
1350 */
1351 pgoff = linear_page_index(vma, pmd_addr);
1352 max_pgoff = (i_size_read(inode) - 1) >> PAGE_SHIFT;
1353
Dave Jiangf4200392017-02-22 15:40:06 -08001354 trace_dax_pmd_fault(inode, vmf, max_pgoff, 0);
Ross Zwisler282a8e02017-02-22 15:39:50 -08001355
Ross Zwisler642261a2016-11-08 11:34:45 +11001356 /* Fall back to PTEs if we're going to COW */
1357 if (write && !(vma->vm_flags & VM_SHARED))
1358 goto fallback;
1359
1360 /* If the PMD would extend outside the VMA */
1361 if (pmd_addr < vma->vm_start)
1362 goto fallback;
1363 if ((pmd_addr + PMD_SIZE) > vma->vm_end)
1364 goto fallback;
1365
Ross Zwisler282a8e02017-02-22 15:39:50 -08001366 if (pgoff > max_pgoff) {
1367 result = VM_FAULT_SIGBUS;
1368 goto out;
1369 }
Ross Zwisler642261a2016-11-08 11:34:45 +11001370
1371 /* If the PMD would extend beyond the file size */
1372 if ((pgoff | PG_PMD_COLOUR) > max_pgoff)
1373 goto fallback;
1374
1375 /*
Ross Zwisler642261a2016-11-08 11:34:45 +11001376 * Note that we don't use iomap_apply here. We aren't doing I/O, only
1377 * setting up a mapping, so really we're using iomap_begin() as a way
1378 * to look up our filesystem block.
1379 */
1380 pos = (loff_t)pgoff << PAGE_SHIFT;
1381 error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
1382 if (error)
Jan Kara9f141d62016-10-19 14:34:31 +02001383 goto fallback;
1384
Ross Zwisler642261a2016-11-08 11:34:45 +11001385 if (iomap.offset + iomap.length < pos + PMD_SIZE)
1386 goto finish_iomap;
1387
Jan Kara9f141d62016-10-19 14:34:31 +02001388 /*
1389 * grab_mapping_entry() will make sure we get a 2M empty entry, a DAX
1390 * PMD or a HZP entry. If it can't (because a 4k page is already in
1391 * the tree, for instance), it will return -EEXIST and we just fall
1392 * back to 4k entries.
1393 */
1394 entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
1395 if (IS_ERR(entry))
1396 goto finish_iomap;
1397
Ross Zwisler642261a2016-11-08 11:34:45 +11001398 switch (iomap.type) {
1399 case IOMAP_MAPPED:
Dave Jiangf4200392017-02-22 15:40:06 -08001400 result = dax_pmd_insert_mapping(vmf, &iomap, pos, &entry);
Ross Zwisler642261a2016-11-08 11:34:45 +11001401 break;
1402 case IOMAP_UNWRITTEN:
1403 case IOMAP_HOLE:
1404 if (WARN_ON_ONCE(write))
Jan Kara9f141d62016-10-19 14:34:31 +02001405 goto unlock_entry;
Dave Jiangf4200392017-02-22 15:40:06 -08001406 result = dax_pmd_load_hole(vmf, &iomap, &entry);
Ross Zwisler642261a2016-11-08 11:34:45 +11001407 break;
1408 default:
1409 WARN_ON_ONCE(1);
1410 break;
1411 }
1412
Ross Zwisler642261a2016-11-08 11:34:45 +11001413 unlock_entry:
1414 put_locked_mapping_entry(mapping, pgoff, entry);
Jan Kara9f141d62016-10-19 14:34:31 +02001415 finish_iomap:
1416 if (ops->iomap_end) {
1417 int copied = PMD_SIZE;
1418
1419 if (result == VM_FAULT_FALLBACK)
1420 copied = 0;
1421 /*
1422 * The fault is done by now and there's no way back (other
1423 * thread may be already happily using PMD we have installed).
1424 * Just ignore error from ->iomap_end since we cannot do much
1425 * with it.
1426 */
1427 ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
1428 &iomap);
1429 }
Ross Zwisler642261a2016-11-08 11:34:45 +11001430 fallback:
1431 if (result == VM_FAULT_FALLBACK) {
Dave Jiangd8a849e2017-02-22 15:40:03 -08001432 split_huge_pmd(vma, vmf->pmd, vmf->address);
Ross Zwisler642261a2016-11-08 11:34:45 +11001433 count_vm_event(THP_FAULT_FALLBACK);
1434 }
Ross Zwisler282a8e02017-02-22 15:39:50 -08001435out:
Dave Jiangf4200392017-02-22 15:40:06 -08001436 trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result);
Ross Zwisler642261a2016-11-08 11:34:45 +11001437 return result;
1438}
Dave Jianga2d581672017-02-24 14:56:59 -08001439#else
Arnd Bergmann01cddfe2017-02-27 14:26:44 -08001440static int dax_iomap_pmd_fault(struct vm_fault *vmf,
1441 const struct iomap_ops *ops)
Dave Jianga2d581672017-02-24 14:56:59 -08001442{
1443 return VM_FAULT_FALLBACK;
1444}
Ross Zwisler642261a2016-11-08 11:34:45 +11001445#endif /* CONFIG_FS_DAX_PMD */
Dave Jianga2d581672017-02-24 14:56:59 -08001446
1447/**
1448 * dax_iomap_fault - handle a page fault on a DAX file
1449 * @vmf: The description of the fault
1450 * @ops: iomap ops passed from the file system
1451 *
1452 * When a page fault occurs, filesystems may call this helper in
1453 * their fault handler for DAX files. dax_iomap_fault() assumes the caller
1454 * has done all the necessary locking for page fault to proceed
1455 * successfully.
1456 */
Dave Jiangc791ace2017-02-24 14:57:08 -08001457int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
1458 const struct iomap_ops *ops)
Dave Jianga2d581672017-02-24 14:56:59 -08001459{
Dave Jiangc791ace2017-02-24 14:57:08 -08001460 switch (pe_size) {
1461 case PE_SIZE_PTE:
Dave Jianga2d581672017-02-24 14:56:59 -08001462 return dax_iomap_pte_fault(vmf, ops);
Dave Jiangc791ace2017-02-24 14:57:08 -08001463 case PE_SIZE_PMD:
Dave Jianga2d581672017-02-24 14:56:59 -08001464 return dax_iomap_pmd_fault(vmf, ops);
1465 default:
1466 return VM_FAULT_FALLBACK;
1467 }
1468}
1469EXPORT_SYMBOL_GPL(dax_iomap_fault);