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>
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.
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
17 #include <linux/atomic.h>
18 #include <linux/blkdev.h>
19 #include <linux/buffer_head.h>
20 #include <linux/dax.h>
22 #include <linux/genhd.h>
23 #include <linux/highmem.h>
24 #include <linux/memcontrol.h>
26 #include <linux/mutex.h>
27 #include <linux/pagevec.h>
28 #include <linux/pmem.h>
29 #include <linux/sched.h>
30 #include <linux/uio.h>
31 #include <linux/vmstat.h>
32 #include <linux/pfn_t.h>
33 #include <linux/sizes.h>
34 #include <linux/mmu_notifier.h>
35 #include <linux/iomap.h>
38 /* We choose 4096 entries - same as per-zone page wait tables */
39 #define DAX_WAIT_TABLE_BITS 12
40 #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
42 static wait_queue_head_t wait_table
[DAX_WAIT_TABLE_ENTRIES
];
44 static int __init
init_dax_wait_table(void)
48 for (i
= 0; i
< DAX_WAIT_TABLE_ENTRIES
; i
++)
49 init_waitqueue_head(wait_table
+ i
);
52 fs_initcall(init_dax_wait_table
);
54 static long dax_map_atomic(struct block_device
*bdev
, struct blk_dax_ctl
*dax
)
56 struct request_queue
*q
= bdev
->bd_queue
;
59 dax
->addr
= ERR_PTR(-EIO
);
60 if (blk_queue_enter(q
, true) != 0)
63 rc
= bdev_direct_access(bdev
, dax
);
65 dax
->addr
= ERR_PTR(rc
);
72 static void dax_unmap_atomic(struct block_device
*bdev
,
73 const struct blk_dax_ctl
*dax
)
75 if (IS_ERR(dax
->addr
))
77 blk_queue_exit(bdev
->bd_queue
);
80 static int dax_is_pmd_entry(void *entry
)
82 return (unsigned long)entry
& RADIX_DAX_PMD
;
85 static int dax_is_pte_entry(void *entry
)
87 return !((unsigned long)entry
& RADIX_DAX_PMD
);
90 static int dax_is_zero_entry(void *entry
)
92 return (unsigned long)entry
& RADIX_DAX_HZP
;
95 static int dax_is_empty_entry(void *entry
)
97 return (unsigned long)entry
& RADIX_DAX_EMPTY
;
100 struct page
*read_dax_sector(struct block_device
*bdev
, sector_t n
)
102 struct page
*page
= alloc_pages(GFP_KERNEL
, 0);
103 struct blk_dax_ctl dax
= {
105 .sector
= n
& ~((((int) PAGE_SIZE
) / 512) - 1),
110 return ERR_PTR(-ENOMEM
);
112 rc
= dax_map_atomic(bdev
, &dax
);
115 memcpy_from_pmem(page_address(page
), dax
.addr
, PAGE_SIZE
);
116 dax_unmap_atomic(bdev
, &dax
);
121 * DAX radix tree locking
123 struct exceptional_entry_key
{
124 struct address_space
*mapping
;
128 struct wait_exceptional_entry_queue
{
130 struct exceptional_entry_key key
;
133 static wait_queue_head_t
*dax_entry_waitqueue(struct address_space
*mapping
,
134 pgoff_t index
, void *entry
, struct exceptional_entry_key
*key
)
139 * If 'entry' is a PMD, align the 'index' that we use for the wait
140 * queue to the start of that PMD. This ensures that all offsets in
141 * the range covered by the PMD map to the same bit lock.
143 if (dax_is_pmd_entry(entry
))
144 index
&= ~((1UL << (PMD_SHIFT
- PAGE_SHIFT
)) - 1);
146 key
->mapping
= mapping
;
147 key
->entry_start
= index
;
149 hash
= hash_long((unsigned long)mapping
^ index
, DAX_WAIT_TABLE_BITS
);
150 return wait_table
+ hash
;
153 static int wake_exceptional_entry_func(wait_queue_t
*wait
, unsigned int mode
,
154 int sync
, void *keyp
)
156 struct exceptional_entry_key
*key
= keyp
;
157 struct wait_exceptional_entry_queue
*ewait
=
158 container_of(wait
, struct wait_exceptional_entry_queue
, wait
);
160 if (key
->mapping
!= ewait
->key
.mapping
||
161 key
->entry_start
!= ewait
->key
.entry_start
)
163 return autoremove_wake_function(wait
, mode
, sync
, NULL
);
167 * Check whether the given slot is locked. The function must be called with
168 * mapping->tree_lock held
170 static inline int slot_locked(struct address_space
*mapping
, void **slot
)
172 unsigned long entry
= (unsigned long)
173 radix_tree_deref_slot_protected(slot
, &mapping
->tree_lock
);
174 return entry
& RADIX_DAX_ENTRY_LOCK
;
178 * Mark the given slot is locked. The function must be called with
179 * mapping->tree_lock held
181 static inline void *lock_slot(struct address_space
*mapping
, void **slot
)
183 unsigned long entry
= (unsigned long)
184 radix_tree_deref_slot_protected(slot
, &mapping
->tree_lock
);
186 entry
|= RADIX_DAX_ENTRY_LOCK
;
187 radix_tree_replace_slot(&mapping
->page_tree
, slot
, (void *)entry
);
188 return (void *)entry
;
192 * Mark the given slot is unlocked. The function must be called with
193 * mapping->tree_lock held
195 static inline void *unlock_slot(struct address_space
*mapping
, void **slot
)
197 unsigned long entry
= (unsigned long)
198 radix_tree_deref_slot_protected(slot
, &mapping
->tree_lock
);
200 entry
&= ~(unsigned long)RADIX_DAX_ENTRY_LOCK
;
201 radix_tree_replace_slot(&mapping
->page_tree
, slot
, (void *)entry
);
202 return (void *)entry
;
206 * Lookup entry in radix tree, wait for it to become unlocked if it is
207 * exceptional entry and return it. The caller must call
208 * put_unlocked_mapping_entry() when he decided not to lock the entry or
209 * put_locked_mapping_entry() when he locked the entry and now wants to
212 * The function must be called with mapping->tree_lock held.
214 static void *get_unlocked_mapping_entry(struct address_space
*mapping
,
215 pgoff_t index
, void ***slotp
)
218 struct wait_exceptional_entry_queue ewait
;
219 wait_queue_head_t
*wq
;
221 init_wait(&ewait
.wait
);
222 ewait
.wait
.func
= wake_exceptional_entry_func
;
225 entry
= __radix_tree_lookup(&mapping
->page_tree
, index
, NULL
,
227 if (!entry
|| !radix_tree_exceptional_entry(entry
) ||
228 !slot_locked(mapping
, slot
)) {
234 wq
= dax_entry_waitqueue(mapping
, index
, entry
, &ewait
.key
);
235 prepare_to_wait_exclusive(wq
, &ewait
.wait
,
236 TASK_UNINTERRUPTIBLE
);
237 spin_unlock_irq(&mapping
->tree_lock
);
239 finish_wait(wq
, &ewait
.wait
);
240 spin_lock_irq(&mapping
->tree_lock
);
244 static void dax_unlock_mapping_entry(struct address_space
*mapping
,
249 spin_lock_irq(&mapping
->tree_lock
);
250 entry
= __radix_tree_lookup(&mapping
->page_tree
, index
, NULL
, &slot
);
251 if (WARN_ON_ONCE(!entry
|| !radix_tree_exceptional_entry(entry
) ||
252 !slot_locked(mapping
, slot
))) {
253 spin_unlock_irq(&mapping
->tree_lock
);
256 unlock_slot(mapping
, slot
);
257 spin_unlock_irq(&mapping
->tree_lock
);
258 dax_wake_mapping_entry_waiter(mapping
, index
, entry
, false);
261 static void put_locked_mapping_entry(struct address_space
*mapping
,
262 pgoff_t index
, void *entry
)
264 if (!radix_tree_exceptional_entry(entry
)) {
268 dax_unlock_mapping_entry(mapping
, index
);
273 * Called when we are done with radix tree entry we looked up via
274 * get_unlocked_mapping_entry() and which we didn't lock in the end.
276 static void put_unlocked_mapping_entry(struct address_space
*mapping
,
277 pgoff_t index
, void *entry
)
279 if (!radix_tree_exceptional_entry(entry
))
282 /* We have to wake up next waiter for the radix tree entry lock */
283 dax_wake_mapping_entry_waiter(mapping
, index
, entry
, false);
287 * Find radix tree entry at given index. If it points to a page, return with
288 * the page locked. If it points to the exceptional entry, return with the
289 * radix tree entry locked. If the radix tree doesn't contain given index,
290 * create empty exceptional entry for the index and return with it locked.
292 * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
293 * either return that locked entry or will return an error. This error will
294 * happen if there are any 4k entries (either zero pages or DAX entries)
295 * within the 2MiB range that we are requesting.
297 * We always favor 4k entries over 2MiB entries. There isn't a flow where we
298 * evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB
299 * insertion will fail if it finds any 4k entries already in the tree, and a
300 * 4k insertion will cause an existing 2MiB entry to be unmapped and
301 * downgraded to 4k entries. This happens for both 2MiB huge zero pages as
302 * well as 2MiB empty entries.
304 * The exception to this downgrade path is for 2MiB DAX PMD entries that have
305 * real storage backing them. We will leave these real 2MiB DAX entries in
306 * the tree, and PTE writes will simply dirty the entire 2MiB DAX entry.
308 * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For
309 * persistent memory the benefit is doubtful. We can add that later if we can
312 static void *grab_mapping_entry(struct address_space
*mapping
, pgoff_t index
,
313 unsigned long size_flag
)
315 bool pmd_downgrade
= false; /* splitting 2MiB entry into 4k entries? */
319 spin_lock_irq(&mapping
->tree_lock
);
320 entry
= get_unlocked_mapping_entry(mapping
, index
, &slot
);
323 if (size_flag
& RADIX_DAX_PMD
) {
324 if (!radix_tree_exceptional_entry(entry
) ||
325 dax_is_pte_entry(entry
)) {
326 put_unlocked_mapping_entry(mapping
, index
,
328 entry
= ERR_PTR(-EEXIST
);
331 } else { /* trying to grab a PTE entry */
332 if (radix_tree_exceptional_entry(entry
) &&
333 dax_is_pmd_entry(entry
) &&
334 (dax_is_zero_entry(entry
) ||
335 dax_is_empty_entry(entry
))) {
336 pmd_downgrade
= true;
341 /* No entry for given index? Make sure radix tree is big enough. */
342 if (!entry
|| pmd_downgrade
) {
347 * Make sure 'entry' remains valid while we drop
348 * mapping->tree_lock.
350 entry
= lock_slot(mapping
, slot
);
353 spin_unlock_irq(&mapping
->tree_lock
);
355 * Besides huge zero pages the only other thing that gets
356 * downgraded are empty entries which don't need to be
359 if (pmd_downgrade
&& dax_is_zero_entry(entry
))
360 unmap_mapping_range(mapping
,
361 (index
<< PAGE_SHIFT
) & PMD_MASK
, PMD_SIZE
, 0);
363 err
= radix_tree_preload(
364 mapping_gfp_mask(mapping
) & ~__GFP_HIGHMEM
);
367 put_locked_mapping_entry(mapping
, index
, entry
);
370 spin_lock_irq(&mapping
->tree_lock
);
373 radix_tree_delete(&mapping
->page_tree
, index
);
374 mapping
->nrexceptional
--;
375 dax_wake_mapping_entry_waiter(mapping
, index
, entry
,
379 entry
= dax_radix_locked_entry(0, size_flag
| RADIX_DAX_EMPTY
);
381 err
= __radix_tree_insert(&mapping
->page_tree
, index
,
382 dax_radix_order(entry
), entry
);
383 radix_tree_preload_end();
385 spin_unlock_irq(&mapping
->tree_lock
);
387 * Someone already created the entry? This is a
388 * normal failure when inserting PMDs in a range
389 * that already contains PTEs. In that case we want
390 * to return -EEXIST immediately.
392 if (err
== -EEXIST
&& !(size_flag
& RADIX_DAX_PMD
))
395 * Our insertion of a DAX PMD entry failed, most
396 * likely because it collided with a PTE sized entry
397 * at a different index in the PMD range. We haven't
398 * inserted anything into the radix tree and have no
403 /* Good, we have inserted empty locked entry into the tree. */
404 mapping
->nrexceptional
++;
405 spin_unlock_irq(&mapping
->tree_lock
);
408 /* Normal page in radix tree? */
409 if (!radix_tree_exceptional_entry(entry
)) {
410 struct page
*page
= entry
;
413 spin_unlock_irq(&mapping
->tree_lock
);
415 /* Page got truncated? Retry... */
416 if (unlikely(page
->mapping
!= mapping
)) {
423 entry
= lock_slot(mapping
, slot
);
425 spin_unlock_irq(&mapping
->tree_lock
);
430 * We do not necessarily hold the mapping->tree_lock when we call this
431 * function so it is possible that 'entry' is no longer a valid item in the
432 * radix tree. This is okay because all we really need to do is to find the
433 * correct waitqueue where tasks might be waiting for that old 'entry' and
436 void dax_wake_mapping_entry_waiter(struct address_space
*mapping
,
437 pgoff_t index
, void *entry
, bool wake_all
)
439 struct exceptional_entry_key key
;
440 wait_queue_head_t
*wq
;
442 wq
= dax_entry_waitqueue(mapping
, index
, entry
, &key
);
445 * Checking for locked entry and prepare_to_wait_exclusive() happens
446 * under mapping->tree_lock, ditto for entry handling in our callers.
447 * So at this point all tasks that could have seen our entry locked
448 * must be in the waitqueue and the following check will see them.
450 if (waitqueue_active(wq
))
451 __wake_up(wq
, TASK_NORMAL
, wake_all
? 0 : 1, &key
);
455 * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
456 * entry to get unlocked before deleting it.
458 int dax_delete_mapping_entry(struct address_space
*mapping
, pgoff_t index
)
462 spin_lock_irq(&mapping
->tree_lock
);
463 entry
= get_unlocked_mapping_entry(mapping
, index
, NULL
);
465 * This gets called from truncate / punch_hole path. As such, the caller
466 * must hold locks protecting against concurrent modifications of the
467 * radix tree (usually fs-private i_mmap_sem for writing). Since the
468 * caller has seen exceptional entry for this index, we better find it
469 * at that index as well...
471 if (WARN_ON_ONCE(!entry
|| !radix_tree_exceptional_entry(entry
))) {
472 spin_unlock_irq(&mapping
->tree_lock
);
475 radix_tree_delete(&mapping
->page_tree
, index
);
476 mapping
->nrexceptional
--;
477 spin_unlock_irq(&mapping
->tree_lock
);
478 dax_wake_mapping_entry_waiter(mapping
, index
, entry
, true);
484 * The user has performed a load from a hole in the file. Allocating
485 * a new page in the file would cause excessive storage usage for
486 * workloads with sparse files. We allocate a page cache page instead.
487 * We'll kick it out of the page cache if it's ever written to,
488 * otherwise it will simply fall out of the page cache under memory
489 * pressure without ever having been dirtied.
491 static int dax_load_hole(struct address_space
*mapping
, void *entry
,
492 struct vm_fault
*vmf
)
496 /* Hole page already exists? Return it... */
497 if (!radix_tree_exceptional_entry(entry
)) {
499 return VM_FAULT_LOCKED
;
502 /* This will replace locked radix tree entry with a hole page */
503 page
= find_or_create_page(mapping
, vmf
->pgoff
,
504 vmf
->gfp_mask
| __GFP_ZERO
);
508 return VM_FAULT_LOCKED
;
511 static int copy_user_dax(struct block_device
*bdev
, sector_t sector
, size_t size
,
512 struct page
*to
, unsigned long vaddr
)
514 struct blk_dax_ctl dax
= {
520 if (dax_map_atomic(bdev
, &dax
) < 0)
521 return PTR_ERR(dax
.addr
);
522 vto
= kmap_atomic(to
);
523 copy_user_page(vto
, (void __force
*)dax
.addr
, vaddr
, to
);
525 dax_unmap_atomic(bdev
, &dax
);
530 * By this point grab_mapping_entry() has ensured that we have a locked entry
531 * of the appropriate size so we don't have to worry about downgrading PMDs to
532 * PTEs. If we happen to be trying to insert a PTE and there is a PMD
533 * already in the tree, we will skip the insertion and just dirty the PMD as
536 static void *dax_insert_mapping_entry(struct address_space
*mapping
,
537 struct vm_fault
*vmf
,
538 void *entry
, sector_t sector
,
541 struct radix_tree_root
*page_tree
= &mapping
->page_tree
;
543 bool hole_fill
= false;
545 pgoff_t index
= vmf
->pgoff
;
547 if (vmf
->flags
& FAULT_FLAG_WRITE
)
548 __mark_inode_dirty(mapping
->host
, I_DIRTY_PAGES
);
550 /* Replacing hole page with block mapping? */
551 if (!radix_tree_exceptional_entry(entry
)) {
554 * Unmap the page now before we remove it from page cache below.
555 * The page is locked so it cannot be faulted in again.
557 unmap_mapping_range(mapping
, vmf
->pgoff
<< PAGE_SHIFT
,
559 error
= radix_tree_preload(vmf
->gfp_mask
& ~__GFP_HIGHMEM
);
561 return ERR_PTR(error
);
562 } else if (dax_is_zero_entry(entry
) && !(flags
& RADIX_DAX_HZP
)) {
563 /* replacing huge zero page with PMD block mapping */
564 unmap_mapping_range(mapping
,
565 (vmf
->pgoff
<< PAGE_SHIFT
) & PMD_MASK
, PMD_SIZE
, 0);
568 spin_lock_irq(&mapping
->tree_lock
);
569 new_entry
= dax_radix_locked_entry(sector
, flags
);
572 __delete_from_page_cache(entry
, NULL
);
573 /* Drop pagecache reference */
575 error
= __radix_tree_insert(page_tree
, index
,
576 dax_radix_order(new_entry
), new_entry
);
578 new_entry
= ERR_PTR(error
);
581 mapping
->nrexceptional
++;
582 } else if (dax_is_zero_entry(entry
) || dax_is_empty_entry(entry
)) {
584 * Only swap our new entry into the radix tree if the current
585 * entry is a zero page or an empty entry. If a normal PTE or
586 * PMD entry is already in the tree, we leave it alone. This
587 * means that if we are trying to insert a PTE and the
588 * existing entry is a PMD, we will just leave the PMD in the
589 * tree and dirty it if necessary.
591 struct radix_tree_node
*node
;
595 ret
= __radix_tree_lookup(page_tree
, index
, &node
, &slot
);
596 WARN_ON_ONCE(ret
!= entry
);
597 __radix_tree_replace(page_tree
, node
, slot
,
598 new_entry
, NULL
, NULL
);
600 if (vmf
->flags
& FAULT_FLAG_WRITE
)
601 radix_tree_tag_set(page_tree
, index
, PAGECACHE_TAG_DIRTY
);
603 spin_unlock_irq(&mapping
->tree_lock
);
605 radix_tree_preload_end();
607 * We don't need hole page anymore, it has been replaced with
608 * locked radix tree entry now.
610 if (mapping
->a_ops
->freepage
)
611 mapping
->a_ops
->freepage(entry
);
618 static inline unsigned long
619 pgoff_address(pgoff_t pgoff
, struct vm_area_struct
*vma
)
621 unsigned long address
;
623 address
= vma
->vm_start
+ ((pgoff
- vma
->vm_pgoff
) << PAGE_SHIFT
);
624 VM_BUG_ON_VMA(address
< vma
->vm_start
|| address
>= vma
->vm_end
, vma
);
628 /* Walk all mappings of a given index of a file and writeprotect them */
629 static void dax_mapping_entry_mkclean(struct address_space
*mapping
,
630 pgoff_t index
, unsigned long pfn
)
632 struct vm_area_struct
*vma
;
638 i_mmap_lock_read(mapping
);
639 vma_interval_tree_foreach(vma
, &mapping
->i_mmap
, index
, index
) {
640 unsigned long address
;
644 if (!(vma
->vm_flags
& VM_SHARED
))
647 address
= pgoff_address(index
, vma
);
649 if (follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
))
651 if (pfn
!= pte_pfn(*ptep
))
653 if (!pte_dirty(*ptep
) && !pte_write(*ptep
))
656 flush_cache_page(vma
, address
, pfn
);
657 pte
= ptep_clear_flush(vma
, address
, ptep
);
658 pte
= pte_wrprotect(pte
);
659 pte
= pte_mkclean(pte
);
660 set_pte_at(vma
->vm_mm
, address
, ptep
, pte
);
663 pte_unmap_unlock(ptep
, ptl
);
666 mmu_notifier_invalidate_page(vma
->vm_mm
, address
);
668 i_mmap_unlock_read(mapping
);
671 static int dax_writeback_one(struct block_device
*bdev
,
672 struct address_space
*mapping
, pgoff_t index
, void *entry
)
674 struct radix_tree_root
*page_tree
= &mapping
->page_tree
;
675 struct blk_dax_ctl dax
;
676 void *entry2
, **slot
;
680 * A page got tagged dirty in DAX mapping? Something is seriously
683 if (WARN_ON(!radix_tree_exceptional_entry(entry
)))
686 spin_lock_irq(&mapping
->tree_lock
);
687 entry2
= get_unlocked_mapping_entry(mapping
, index
, &slot
);
688 /* Entry got punched out / reallocated? */
689 if (!entry2
|| !radix_tree_exceptional_entry(entry2
))
692 * Entry got reallocated elsewhere? No need to writeback. We have to
693 * compare sectors as we must not bail out due to difference in lockbit
696 if (dax_radix_sector(entry2
) != dax_radix_sector(entry
))
698 if (WARN_ON_ONCE(dax_is_empty_entry(entry
) ||
699 dax_is_zero_entry(entry
))) {
704 /* Another fsync thread may have already written back this entry */
705 if (!radix_tree_tag_get(page_tree
, index
, PAGECACHE_TAG_TOWRITE
))
707 /* Lock the entry to serialize with page faults */
708 entry
= lock_slot(mapping
, slot
);
710 * We can clear the tag now but we have to be careful so that concurrent
711 * dax_writeback_one() calls for the same index cannot finish before we
712 * actually flush the caches. This is achieved as the calls will look
713 * at the entry only under tree_lock and once they do that they will
714 * see the entry locked and wait for it to unlock.
716 radix_tree_tag_clear(page_tree
, index
, PAGECACHE_TAG_TOWRITE
);
717 spin_unlock_irq(&mapping
->tree_lock
);
720 * Even if dax_writeback_mapping_range() was given a wbc->range_start
721 * in the middle of a PMD, the 'index' we are given will be aligned to
722 * the start index of the PMD, as will the sector we pull from
723 * 'entry'. This allows us to flush for PMD_SIZE and not have to
724 * worry about partial PMD writebacks.
726 dax
.sector
= dax_radix_sector(entry
);
727 dax
.size
= PAGE_SIZE
<< dax_radix_order(entry
);
730 * We cannot hold tree_lock while calling dax_map_atomic() because it
731 * eventually calls cond_resched().
733 ret
= dax_map_atomic(bdev
, &dax
);
735 put_locked_mapping_entry(mapping
, index
, entry
);
739 if (WARN_ON_ONCE(ret
< dax
.size
)) {
744 dax_mapping_entry_mkclean(mapping
, index
, pfn_t_to_pfn(dax
.pfn
));
745 wb_cache_pmem(dax
.addr
, dax
.size
);
747 * After we have flushed the cache, we can clear the dirty tag. There
748 * cannot be new dirty data in the pfn after the flush has completed as
749 * the pfn mappings are writeprotected and fault waits for mapping
752 spin_lock_irq(&mapping
->tree_lock
);
753 radix_tree_tag_clear(page_tree
, index
, PAGECACHE_TAG_DIRTY
);
754 spin_unlock_irq(&mapping
->tree_lock
);
756 dax_unmap_atomic(bdev
, &dax
);
757 put_locked_mapping_entry(mapping
, index
, entry
);
761 put_unlocked_mapping_entry(mapping
, index
, entry2
);
762 spin_unlock_irq(&mapping
->tree_lock
);
767 * Flush the mapping to the persistent domain within the byte range of [start,
768 * end]. This is required by data integrity operations to ensure file data is
769 * on persistent storage prior to completion of the operation.
771 int dax_writeback_mapping_range(struct address_space
*mapping
,
772 struct block_device
*bdev
, struct writeback_control
*wbc
)
774 struct inode
*inode
= mapping
->host
;
775 pgoff_t start_index
, end_index
;
776 pgoff_t indices
[PAGEVEC_SIZE
];
781 if (WARN_ON_ONCE(inode
->i_blkbits
!= PAGE_SHIFT
))
784 if (!mapping
->nrexceptional
|| wbc
->sync_mode
!= WB_SYNC_ALL
)
787 start_index
= wbc
->range_start
>> PAGE_SHIFT
;
788 end_index
= wbc
->range_end
>> PAGE_SHIFT
;
790 tag_pages_for_writeback(mapping
, start_index
, end_index
);
792 pagevec_init(&pvec
, 0);
794 pvec
.nr
= find_get_entries_tag(mapping
, start_index
,
795 PAGECACHE_TAG_TOWRITE
, PAGEVEC_SIZE
,
796 pvec
.pages
, indices
);
801 for (i
= 0; i
< pvec
.nr
; i
++) {
802 if (indices
[i
] > end_index
) {
807 ret
= dax_writeback_one(bdev
, mapping
, indices
[i
],
815 EXPORT_SYMBOL_GPL(dax_writeback_mapping_range
);
817 static int dax_insert_mapping(struct address_space
*mapping
,
818 struct block_device
*bdev
, sector_t sector
, size_t size
,
819 void **entryp
, struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
821 unsigned long vaddr
= vmf
->address
;
822 struct blk_dax_ctl dax
= {
827 void *entry
= *entryp
;
829 if (dax_map_atomic(bdev
, &dax
) < 0)
830 return PTR_ERR(dax
.addr
);
831 dax_unmap_atomic(bdev
, &dax
);
833 ret
= dax_insert_mapping_entry(mapping
, vmf
, entry
, dax
.sector
, 0);
838 return vm_insert_mixed(vma
, vaddr
, dax
.pfn
);
842 * dax_pfn_mkwrite - handle first write to DAX page
843 * @vma: The virtual memory area where the fault occurred
844 * @vmf: The description of the fault
846 int dax_pfn_mkwrite(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
848 struct file
*file
= vma
->vm_file
;
849 struct address_space
*mapping
= file
->f_mapping
;
851 pgoff_t index
= vmf
->pgoff
;
853 spin_lock_irq(&mapping
->tree_lock
);
854 entry
= get_unlocked_mapping_entry(mapping
, index
, &slot
);
855 if (!entry
|| !radix_tree_exceptional_entry(entry
)) {
857 put_unlocked_mapping_entry(mapping
, index
, entry
);
858 spin_unlock_irq(&mapping
->tree_lock
);
859 return VM_FAULT_NOPAGE
;
861 radix_tree_tag_set(&mapping
->page_tree
, index
, PAGECACHE_TAG_DIRTY
);
862 entry
= lock_slot(mapping
, slot
);
863 spin_unlock_irq(&mapping
->tree_lock
);
865 * If we race with somebody updating the PTE and finish_mkwrite_fault()
866 * fails, we don't care. We need to return VM_FAULT_NOPAGE and retry
867 * the fault in either case.
869 finish_mkwrite_fault(vmf
);
870 put_locked_mapping_entry(mapping
, index
, entry
);
871 return VM_FAULT_NOPAGE
;
873 EXPORT_SYMBOL_GPL(dax_pfn_mkwrite
);
875 static bool dax_range_is_aligned(struct block_device
*bdev
,
876 unsigned int offset
, unsigned int length
)
878 unsigned short sector_size
= bdev_logical_block_size(bdev
);
880 if (!IS_ALIGNED(offset
, sector_size
))
882 if (!IS_ALIGNED(length
, sector_size
))
888 int __dax_zero_page_range(struct block_device
*bdev
, sector_t sector
,
889 unsigned int offset
, unsigned int length
)
891 struct blk_dax_ctl dax
= {
896 if (dax_range_is_aligned(bdev
, offset
, length
)) {
897 sector_t start_sector
= dax
.sector
+ (offset
>> 9);
899 return blkdev_issue_zeroout(bdev
, start_sector
,
900 length
>> 9, GFP_NOFS
, true);
902 if (dax_map_atomic(bdev
, &dax
) < 0)
903 return PTR_ERR(dax
.addr
);
904 clear_pmem(dax
.addr
+ offset
, length
);
905 dax_unmap_atomic(bdev
, &dax
);
909 EXPORT_SYMBOL_GPL(__dax_zero_page_range
);
911 #ifdef CONFIG_FS_IOMAP
912 static sector_t
dax_iomap_sector(struct iomap
*iomap
, loff_t pos
)
914 return iomap
->blkno
+ (((pos
& PAGE_MASK
) - iomap
->offset
) >> 9);
918 dax_iomap_actor(struct inode
*inode
, loff_t pos
, loff_t length
, void *data
,
921 struct iov_iter
*iter
= data
;
922 loff_t end
= pos
+ length
, done
= 0;
925 if (iov_iter_rw(iter
) == READ
) {
926 end
= min(end
, i_size_read(inode
));
930 if (iomap
->type
== IOMAP_HOLE
|| iomap
->type
== IOMAP_UNWRITTEN
)
931 return iov_iter_zero(min(length
, end
- pos
), iter
);
934 if (WARN_ON_ONCE(iomap
->type
!= IOMAP_MAPPED
))
938 unsigned offset
= pos
& (PAGE_SIZE
- 1);
939 struct blk_dax_ctl dax
= { 0 };
942 dax
.sector
= dax_iomap_sector(iomap
, pos
);
943 dax
.size
= (length
+ offset
+ PAGE_SIZE
- 1) & PAGE_MASK
;
944 map_len
= dax_map_atomic(iomap
->bdev
, &dax
);
952 if (map_len
> end
- pos
)
955 if (iov_iter_rw(iter
) == WRITE
)
956 map_len
= copy_from_iter_pmem(dax
.addr
, map_len
, iter
);
958 map_len
= copy_to_iter(dax
.addr
, map_len
, iter
);
959 dax_unmap_atomic(iomap
->bdev
, &dax
);
961 ret
= map_len
? map_len
: -EFAULT
;
970 return done
? done
: ret
;
974 * dax_iomap_rw - Perform I/O to a DAX file
975 * @iocb: The control block for this I/O
976 * @iter: The addresses to do I/O from or to
977 * @ops: iomap ops passed from the file system
979 * This function performs read and write operations to directly mapped
980 * persistent memory. The callers needs to take care of read/write exclusion
981 * and evicting any page cache pages in the region under I/O.
984 dax_iomap_rw(struct kiocb
*iocb
, struct iov_iter
*iter
,
985 struct iomap_ops
*ops
)
987 struct address_space
*mapping
= iocb
->ki_filp
->f_mapping
;
988 struct inode
*inode
= mapping
->host
;
989 loff_t pos
= iocb
->ki_pos
, ret
= 0, done
= 0;
992 if (iov_iter_rw(iter
) == WRITE
)
993 flags
|= IOMAP_WRITE
;
996 * Yes, even DAX files can have page cache attached to them: A zeroed
997 * page is inserted into the pagecache when we have to serve a write
998 * fault on a hole. It should never be dirtied and can simply be
999 * dropped from the pagecache once we get real data for the page.
1001 * XXX: This is racy against mmap, and there's nothing we can do about
1002 * it. We'll eventually need to shift this down even further so that
1003 * we can check if we allocated blocks over a hole first.
1005 if (mapping
->nrpages
) {
1006 ret
= invalidate_inode_pages2_range(mapping
,
1008 (pos
+ iov_iter_count(iter
) - 1) >> PAGE_SHIFT
);
1012 while (iov_iter_count(iter
)) {
1013 ret
= iomap_apply(inode
, pos
, iov_iter_count(iter
), flags
, ops
,
1014 iter
, dax_iomap_actor
);
1021 iocb
->ki_pos
+= done
;
1022 return done
? done
: ret
;
1024 EXPORT_SYMBOL_GPL(dax_iomap_rw
);
1027 * dax_iomap_fault - handle a page fault on a DAX file
1028 * @vma: The virtual memory area where the fault occurred
1029 * @vmf: The description of the fault
1030 * @ops: iomap ops passed from the file system
1032 * When a page fault occurs, filesystems may call this helper in their fault
1033 * or mkwrite handler for DAX files. Assumes the caller has done all the
1034 * necessary locking for the page fault to proceed successfully.
1036 int dax_iomap_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
,
1037 struct iomap_ops
*ops
)
1039 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
1040 struct inode
*inode
= mapping
->host
;
1041 unsigned long vaddr
= vmf
->address
;
1042 loff_t pos
= (loff_t
)vmf
->pgoff
<< PAGE_SHIFT
;
1044 struct iomap iomap
= { 0 };
1045 unsigned flags
= IOMAP_FAULT
;
1046 int error
, major
= 0;
1051 * Check whether offset isn't beyond end of file now. Caller is supposed
1052 * to hold locks serializing us with truncate / punch hole so this is
1055 if (pos
>= i_size_read(inode
))
1056 return VM_FAULT_SIGBUS
;
1058 entry
= grab_mapping_entry(mapping
, vmf
->pgoff
, 0);
1059 if (IS_ERR(entry
)) {
1060 error
= PTR_ERR(entry
);
1064 if ((vmf
->flags
& FAULT_FLAG_WRITE
) && !vmf
->cow_page
)
1065 flags
|= IOMAP_WRITE
;
1068 * Note that we don't bother to use iomap_apply here: DAX required
1069 * the file system block size to be equal the page size, which means
1070 * that we never have to deal with more than a single extent here.
1072 error
= ops
->iomap_begin(inode
, pos
, PAGE_SIZE
, flags
, &iomap
);
1075 if (WARN_ON_ONCE(iomap
.offset
+ iomap
.length
< pos
+ PAGE_SIZE
)) {
1076 error
= -EIO
; /* fs corruption? */
1080 sector
= dax_iomap_sector(&iomap
, pos
);
1082 if (vmf
->cow_page
) {
1083 switch (iomap
.type
) {
1085 case IOMAP_UNWRITTEN
:
1086 clear_user_highpage(vmf
->cow_page
, vaddr
);
1089 error
= copy_user_dax(iomap
.bdev
, sector
, PAGE_SIZE
,
1090 vmf
->cow_page
, vaddr
);
1101 __SetPageUptodate(vmf
->cow_page
);
1102 vmf_ret
= finish_fault(vmf
);
1104 vmf_ret
= VM_FAULT_DONE_COW
;
1108 switch (iomap
.type
) {
1110 if (iomap
.flags
& IOMAP_F_NEW
) {
1111 count_vm_event(PGMAJFAULT
);
1112 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1113 major
= VM_FAULT_MAJOR
;
1115 error
= dax_insert_mapping(mapping
, iomap
.bdev
, sector
,
1116 PAGE_SIZE
, &entry
, vma
, vmf
);
1118 case IOMAP_UNWRITTEN
:
1120 if (!(vmf
->flags
& FAULT_FLAG_WRITE
)) {
1121 vmf_ret
= dax_load_hole(mapping
, entry
, vmf
);
1132 if (ops
->iomap_end
) {
1133 if (error
|| (vmf_ret
& VM_FAULT_ERROR
)) {
1134 /* keep previous error */
1135 ops
->iomap_end(inode
, pos
, PAGE_SIZE
, 0, flags
,
1138 error
= ops
->iomap_end(inode
, pos
, PAGE_SIZE
,
1139 PAGE_SIZE
, flags
, &iomap
);
1143 if (vmf_ret
!= VM_FAULT_LOCKED
|| error
)
1144 put_locked_mapping_entry(mapping
, vmf
->pgoff
, entry
);
1146 if (error
== -ENOMEM
)
1147 return VM_FAULT_OOM
| major
;
1148 /* -EBUSY is fine, somebody else faulted on the same PTE */
1149 if (error
< 0 && error
!= -EBUSY
)
1150 return VM_FAULT_SIGBUS
| major
;
1152 WARN_ON_ONCE(error
); /* -EBUSY from ops->iomap_end? */
1155 return VM_FAULT_NOPAGE
| major
;
1157 EXPORT_SYMBOL_GPL(dax_iomap_fault
);
1159 #ifdef CONFIG_FS_DAX_PMD
1161 * The 'colour' (ie low bits) within a PMD of a page offset. This comes up
1162 * more often than one might expect in the below functions.
1164 #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
1166 static int dax_pmd_insert_mapping(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1167 struct vm_fault
*vmf
, unsigned long address
,
1168 struct iomap
*iomap
, loff_t pos
, bool write
, void **entryp
)
1170 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
1171 struct block_device
*bdev
= iomap
->bdev
;
1172 struct blk_dax_ctl dax
= {
1173 .sector
= dax_iomap_sector(iomap
, pos
),
1176 long length
= dax_map_atomic(bdev
, &dax
);
1179 if (length
< 0) /* dax_map_atomic() failed */
1180 return VM_FAULT_FALLBACK
;
1181 if (length
< PMD_SIZE
)
1182 goto unmap_fallback
;
1183 if (pfn_t_to_pfn(dax
.pfn
) & PG_PMD_COLOUR
)
1184 goto unmap_fallback
;
1185 if (!pfn_t_devmap(dax
.pfn
))
1186 goto unmap_fallback
;
1188 dax_unmap_atomic(bdev
, &dax
);
1190 ret
= dax_insert_mapping_entry(mapping
, vmf
, *entryp
, dax
.sector
,
1193 return VM_FAULT_FALLBACK
;
1196 return vmf_insert_pfn_pmd(vma
, address
, pmd
, dax
.pfn
, write
);
1199 dax_unmap_atomic(bdev
, &dax
);
1200 return VM_FAULT_FALLBACK
;
1203 static int dax_pmd_load_hole(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1204 struct vm_fault
*vmf
, unsigned long address
,
1205 struct iomap
*iomap
, void **entryp
)
1207 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
1208 unsigned long pmd_addr
= address
& PMD_MASK
;
1209 struct page
*zero_page
;
1214 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
1216 if (unlikely(!zero_page
))
1217 return VM_FAULT_FALLBACK
;
1219 ret
= dax_insert_mapping_entry(mapping
, vmf
, *entryp
, 0,
1220 RADIX_DAX_PMD
| RADIX_DAX_HZP
);
1222 return VM_FAULT_FALLBACK
;
1225 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1226 if (!pmd_none(*pmd
)) {
1228 return VM_FAULT_FALLBACK
;
1231 pmd_entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
1232 pmd_entry
= pmd_mkhuge(pmd_entry
);
1233 set_pmd_at(vma
->vm_mm
, pmd_addr
, pmd
, pmd_entry
);
1235 return VM_FAULT_NOPAGE
;
1238 int dax_iomap_pmd_fault(struct vm_area_struct
*vma
, unsigned long address
,
1239 pmd_t
*pmd
, unsigned int flags
, struct iomap_ops
*ops
)
1241 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
1242 unsigned long pmd_addr
= address
& PMD_MASK
;
1243 bool write
= flags
& FAULT_FLAG_WRITE
;
1244 unsigned int iomap_flags
= (write
? IOMAP_WRITE
: 0) | IOMAP_FAULT
;
1245 struct inode
*inode
= mapping
->host
;
1246 int result
= VM_FAULT_FALLBACK
;
1247 struct iomap iomap
= { 0 };
1248 pgoff_t max_pgoff
, pgoff
;
1249 struct vm_fault vmf
;
1254 /* Fall back to PTEs if we're going to COW */
1255 if (write
&& !(vma
->vm_flags
& VM_SHARED
))
1258 /* If the PMD would extend outside the VMA */
1259 if (pmd_addr
< vma
->vm_start
)
1261 if ((pmd_addr
+ PMD_SIZE
) > vma
->vm_end
)
1265 * Check whether offset isn't beyond end of file now. Caller is
1266 * supposed to hold locks serializing us with truncate / punch hole so
1267 * this is a reliable test.
1269 pgoff
= linear_page_index(vma
, pmd_addr
);
1270 max_pgoff
= (i_size_read(inode
) - 1) >> PAGE_SHIFT
;
1272 if (pgoff
> max_pgoff
)
1273 return VM_FAULT_SIGBUS
;
1275 /* If the PMD would extend beyond the file size */
1276 if ((pgoff
| PG_PMD_COLOUR
) > max_pgoff
)
1280 * grab_mapping_entry() will make sure we get a 2M empty entry, a DAX
1281 * PMD or a HZP entry. If it can't (because a 4k page is already in
1282 * the tree, for instance), it will return -EEXIST and we just fall
1283 * back to 4k entries.
1285 entry
= grab_mapping_entry(mapping
, pgoff
, RADIX_DAX_PMD
);
1290 * Note that we don't use iomap_apply here. We aren't doing I/O, only
1291 * setting up a mapping, so really we're using iomap_begin() as a way
1292 * to look up our filesystem block.
1294 pos
= (loff_t
)pgoff
<< PAGE_SHIFT
;
1295 error
= ops
->iomap_begin(inode
, pos
, PMD_SIZE
, iomap_flags
, &iomap
);
1298 if (iomap
.offset
+ iomap
.length
< pos
+ PMD_SIZE
)
1303 vmf
.gfp_mask
= mapping_gfp_mask(mapping
) | __GFP_IO
;
1305 switch (iomap
.type
) {
1307 result
= dax_pmd_insert_mapping(vma
, pmd
, &vmf
, address
,
1308 &iomap
, pos
, write
, &entry
);
1310 case IOMAP_UNWRITTEN
:
1312 if (WARN_ON_ONCE(write
))
1314 result
= dax_pmd_load_hole(vma
, pmd
, &vmf
, address
, &iomap
,
1323 if (ops
->iomap_end
) {
1324 if (result
== VM_FAULT_FALLBACK
) {
1325 ops
->iomap_end(inode
, pos
, PMD_SIZE
, 0, iomap_flags
,
1328 error
= ops
->iomap_end(inode
, pos
, PMD_SIZE
, PMD_SIZE
,
1329 iomap_flags
, &iomap
);
1331 result
= VM_FAULT_FALLBACK
;
1335 put_locked_mapping_entry(mapping
, pgoff
, entry
);
1337 if (result
== VM_FAULT_FALLBACK
) {
1338 split_huge_pmd(vma
, pmd
, address
);
1339 count_vm_event(THP_FAULT_FALLBACK
);
1343 EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault
);
1344 #endif /* CONFIG_FS_DAX_PMD */
1345 #endif /* CONFIG_FS_IOMAP */