1470 строки
40 KiB
C
1470 строки
40 KiB
C
/*
|
|
* fs/dax.c - Direct Access filesystem code
|
|
* Copyright (c) 2013-2014 Intel Corporation
|
|
* Author: Matthew Wilcox <matthew.r.wilcox@intel.com>
|
|
* Author: Ross Zwisler <ross.zwisler@linux.intel.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms and conditions of the GNU General Public License,
|
|
* version 2, as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
* more details.
|
|
*/
|
|
|
|
#include <linux/atomic.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/buffer_head.h>
|
|
#include <linux/dax.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/genhd.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/memcontrol.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/pagevec.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/uio.h>
|
|
#include <linux/vmstat.h>
|
|
#include <linux/pfn_t.h>
|
|
#include <linux/sizes.h>
|
|
#include <linux/mmu_notifier.h>
|
|
#include <linux/iomap.h>
|
|
#include "internal.h"
|
|
|
|
#define CREATE_TRACE_POINTS
|
|
#include <trace/events/fs_dax.h>
|
|
|
|
/* We choose 4096 entries - same as per-zone page wait tables */
|
|
#define DAX_WAIT_TABLE_BITS 12
|
|
#define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
|
|
|
|
/* The 'colour' (ie low bits) within a PMD of a page offset. */
|
|
#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
|
|
|
|
static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
|
|
|
|
static int __init init_dax_wait_table(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++)
|
|
init_waitqueue_head(wait_table + i);
|
|
return 0;
|
|
}
|
|
fs_initcall(init_dax_wait_table);
|
|
|
|
/*
|
|
* We use lowest available bit in exceptional entry for locking, one bit for
|
|
* the entry size (PMD) and two more to tell us if the entry is a zero page or
|
|
* an empty entry that is just used for locking. In total four special bits.
|
|
*
|
|
* If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE
|
|
* and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
|
|
* block allocation.
|
|
*/
|
|
#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
|
|
#define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
|
|
#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
|
|
#define RADIX_DAX_ZERO_PAGE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
|
|
#define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
|
|
|
|
static unsigned long dax_radix_sector(void *entry)
|
|
{
|
|
return (unsigned long)entry >> RADIX_DAX_SHIFT;
|
|
}
|
|
|
|
static void *dax_radix_locked_entry(sector_t sector, unsigned long flags)
|
|
{
|
|
return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
|
|
((unsigned long)sector << RADIX_DAX_SHIFT) |
|
|
RADIX_DAX_ENTRY_LOCK);
|
|
}
|
|
|
|
static unsigned int dax_radix_order(void *entry)
|
|
{
|
|
if ((unsigned long)entry & RADIX_DAX_PMD)
|
|
return PMD_SHIFT - PAGE_SHIFT;
|
|
return 0;
|
|
}
|
|
|
|
static int dax_is_pmd_entry(void *entry)
|
|
{
|
|
return (unsigned long)entry & RADIX_DAX_PMD;
|
|
}
|
|
|
|
static int dax_is_pte_entry(void *entry)
|
|
{
|
|
return !((unsigned long)entry & RADIX_DAX_PMD);
|
|
}
|
|
|
|
static int dax_is_zero_entry(void *entry)
|
|
{
|
|
return (unsigned long)entry & RADIX_DAX_ZERO_PAGE;
|
|
}
|
|
|
|
static int dax_is_empty_entry(void *entry)
|
|
{
|
|
return (unsigned long)entry & RADIX_DAX_EMPTY;
|
|
}
|
|
|
|
/*
|
|
* DAX radix tree locking
|
|
*/
|
|
struct exceptional_entry_key {
|
|
struct address_space *mapping;
|
|
pgoff_t entry_start;
|
|
};
|
|
|
|
struct wait_exceptional_entry_queue {
|
|
wait_queue_entry_t wait;
|
|
struct exceptional_entry_key key;
|
|
};
|
|
|
|
static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
|
|
pgoff_t index, void *entry, struct exceptional_entry_key *key)
|
|
{
|
|
unsigned long hash;
|
|
|
|
/*
|
|
* If 'entry' is a PMD, align the 'index' that we use for the wait
|
|
* queue to the start of that PMD. This ensures that all offsets in
|
|
* the range covered by the PMD map to the same bit lock.
|
|
*/
|
|
if (dax_is_pmd_entry(entry))
|
|
index &= ~PG_PMD_COLOUR;
|
|
|
|
key->mapping = mapping;
|
|
key->entry_start = index;
|
|
|
|
hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS);
|
|
return wait_table + hash;
|
|
}
|
|
|
|
static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mode,
|
|
int sync, void *keyp)
|
|
{
|
|
struct exceptional_entry_key *key = keyp;
|
|
struct wait_exceptional_entry_queue *ewait =
|
|
container_of(wait, struct wait_exceptional_entry_queue, wait);
|
|
|
|
if (key->mapping != ewait->key.mapping ||
|
|
key->entry_start != ewait->key.entry_start)
|
|
return 0;
|
|
return autoremove_wake_function(wait, mode, sync, NULL);
|
|
}
|
|
|
|
/*
|
|
* We do not necessarily hold the mapping->tree_lock when we call this
|
|
* function so it is possible that 'entry' is no longer a valid item in the
|
|
* radix tree. This is okay because all we really need to do is to find the
|
|
* correct waitqueue where tasks might be waiting for that old 'entry' and
|
|
* wake them.
|
|
*/
|
|
static void dax_wake_mapping_entry_waiter(struct address_space *mapping,
|
|
pgoff_t index, void *entry, bool wake_all)
|
|
{
|
|
struct exceptional_entry_key key;
|
|
wait_queue_head_t *wq;
|
|
|
|
wq = dax_entry_waitqueue(mapping, index, entry, &key);
|
|
|
|
/*
|
|
* Checking for locked entry and prepare_to_wait_exclusive() happens
|
|
* under mapping->tree_lock, ditto for entry handling in our callers.
|
|
* So at this point all tasks that could have seen our entry locked
|
|
* must be in the waitqueue and the following check will see them.
|
|
*/
|
|
if (waitqueue_active(wq))
|
|
__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
|
|
}
|
|
|
|
/*
|
|
* Check whether the given slot is locked. The function must be called with
|
|
* mapping->tree_lock held
|
|
*/
|
|
static inline int slot_locked(struct address_space *mapping, void **slot)
|
|
{
|
|
unsigned long entry = (unsigned long)
|
|
radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
|
|
return entry & RADIX_DAX_ENTRY_LOCK;
|
|
}
|
|
|
|
/*
|
|
* Mark the given slot is locked. The function must be called with
|
|
* mapping->tree_lock held
|
|
*/
|
|
static inline void *lock_slot(struct address_space *mapping, void **slot)
|
|
{
|
|
unsigned long entry = (unsigned long)
|
|
radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
|
|
|
|
entry |= RADIX_DAX_ENTRY_LOCK;
|
|
radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
|
|
return (void *)entry;
|
|
}
|
|
|
|
/*
|
|
* Mark the given slot is unlocked. The function must be called with
|
|
* mapping->tree_lock held
|
|
*/
|
|
static inline void *unlock_slot(struct address_space *mapping, void **slot)
|
|
{
|
|
unsigned long entry = (unsigned long)
|
|
radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
|
|
|
|
entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
|
|
radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
|
|
return (void *)entry;
|
|
}
|
|
|
|
/*
|
|
* Lookup entry in radix tree, wait for it to become unlocked if it is
|
|
* exceptional entry and return it. The caller must call
|
|
* put_unlocked_mapping_entry() when he decided not to lock the entry or
|
|
* put_locked_mapping_entry() when he locked the entry and now wants to
|
|
* unlock it.
|
|
*
|
|
* The function must be called with mapping->tree_lock held.
|
|
*/
|
|
static void *get_unlocked_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index, void ***slotp)
|
|
{
|
|
void *entry, **slot;
|
|
struct wait_exceptional_entry_queue ewait;
|
|
wait_queue_head_t *wq;
|
|
|
|
init_wait(&ewait.wait);
|
|
ewait.wait.func = wake_exceptional_entry_func;
|
|
|
|
for (;;) {
|
|
entry = __radix_tree_lookup(&mapping->page_tree, index, NULL,
|
|
&slot);
|
|
if (!entry ||
|
|
WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) ||
|
|
!slot_locked(mapping, slot)) {
|
|
if (slotp)
|
|
*slotp = slot;
|
|
return entry;
|
|
}
|
|
|
|
wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
|
|
prepare_to_wait_exclusive(wq, &ewait.wait,
|
|
TASK_UNINTERRUPTIBLE);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
schedule();
|
|
finish_wait(wq, &ewait.wait);
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
}
|
|
}
|
|
|
|
static void dax_unlock_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index)
|
|
{
|
|
void *entry, **slot;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
|
|
if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
|
|
!slot_locked(mapping, slot))) {
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return;
|
|
}
|
|
unlock_slot(mapping, slot);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
dax_wake_mapping_entry_waiter(mapping, index, entry, false);
|
|
}
|
|
|
|
static void put_locked_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index)
|
|
{
|
|
dax_unlock_mapping_entry(mapping, index);
|
|
}
|
|
|
|
/*
|
|
* Called when we are done with radix tree entry we looked up via
|
|
* get_unlocked_mapping_entry() and which we didn't lock in the end.
|
|
*/
|
|
static void put_unlocked_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index, void *entry)
|
|
{
|
|
if (!entry)
|
|
return;
|
|
|
|
/* We have to wake up next waiter for the radix tree entry lock */
|
|
dax_wake_mapping_entry_waiter(mapping, index, entry, false);
|
|
}
|
|
|
|
/*
|
|
* Find radix tree entry at given index. If it points to an exceptional entry,
|
|
* return it with the radix tree entry locked. If the radix tree doesn't
|
|
* contain given index, create an empty exceptional entry for the index and
|
|
* return with it locked.
|
|
*
|
|
* When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
|
|
* either return that locked entry or will return an error. This error will
|
|
* happen if there are any 4k entries within the 2MiB range that we are
|
|
* requesting.
|
|
*
|
|
* We always favor 4k entries over 2MiB entries. There isn't a flow where we
|
|
* evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB
|
|
* insertion will fail if it finds any 4k entries already in the tree, and a
|
|
* 4k insertion will cause an existing 2MiB entry to be unmapped and
|
|
* downgraded to 4k entries. This happens for both 2MiB huge zero pages as
|
|
* well as 2MiB empty entries.
|
|
*
|
|
* The exception to this downgrade path is for 2MiB DAX PMD entries that have
|
|
* real storage backing them. We will leave these real 2MiB DAX entries in
|
|
* the tree, and PTE writes will simply dirty the entire 2MiB DAX entry.
|
|
*
|
|
* Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For
|
|
* persistent memory the benefit is doubtful. We can add that later if we can
|
|
* show it helps.
|
|
*/
|
|
static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
|
|
unsigned long size_flag)
|
|
{
|
|
bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
|
|
void *entry, **slot;
|
|
|
|
restart:
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = get_unlocked_mapping_entry(mapping, index, &slot);
|
|
|
|
if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) {
|
|
entry = ERR_PTR(-EIO);
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (entry) {
|
|
if (size_flag & RADIX_DAX_PMD) {
|
|
if (dax_is_pte_entry(entry)) {
|
|
put_unlocked_mapping_entry(mapping, index,
|
|
entry);
|
|
entry = ERR_PTR(-EEXIST);
|
|
goto out_unlock;
|
|
}
|
|
} else { /* trying to grab a PTE entry */
|
|
if (dax_is_pmd_entry(entry) &&
|
|
(dax_is_zero_entry(entry) ||
|
|
dax_is_empty_entry(entry))) {
|
|
pmd_downgrade = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* No entry for given index? Make sure radix tree is big enough. */
|
|
if (!entry || pmd_downgrade) {
|
|
int err;
|
|
|
|
if (pmd_downgrade) {
|
|
/*
|
|
* Make sure 'entry' remains valid while we drop
|
|
* mapping->tree_lock.
|
|
*/
|
|
entry = lock_slot(mapping, slot);
|
|
}
|
|
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
/*
|
|
* Besides huge zero pages the only other thing that gets
|
|
* downgraded are empty entries which don't need to be
|
|
* unmapped.
|
|
*/
|
|
if (pmd_downgrade && dax_is_zero_entry(entry))
|
|
unmap_mapping_range(mapping,
|
|
(index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
|
|
|
|
err = radix_tree_preload(
|
|
mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
|
|
if (err) {
|
|
if (pmd_downgrade)
|
|
put_locked_mapping_entry(mapping, index);
|
|
return ERR_PTR(err);
|
|
}
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
|
|
if (!entry) {
|
|
/*
|
|
* We needed to drop the page_tree lock while calling
|
|
* radix_tree_preload() and we didn't have an entry to
|
|
* lock. See if another thread inserted an entry at
|
|
* our index during this time.
|
|
*/
|
|
entry = __radix_tree_lookup(&mapping->page_tree, index,
|
|
NULL, &slot);
|
|
if (entry) {
|
|
radix_tree_preload_end();
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
goto restart;
|
|
}
|
|
}
|
|
|
|
if (pmd_downgrade) {
|
|
radix_tree_delete(&mapping->page_tree, index);
|
|
mapping->nrexceptional--;
|
|
dax_wake_mapping_entry_waiter(mapping, index, entry,
|
|
true);
|
|
}
|
|
|
|
entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
|
|
|
|
err = __radix_tree_insert(&mapping->page_tree, index,
|
|
dax_radix_order(entry), entry);
|
|
radix_tree_preload_end();
|
|
if (err) {
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
/*
|
|
* Our insertion of a DAX entry failed, most likely
|
|
* because we were inserting a PMD entry and it
|
|
* collided with a PTE sized entry at a different
|
|
* index in the PMD range. We haven't inserted
|
|
* anything into the radix tree and have no waiters to
|
|
* wake.
|
|
*/
|
|
return ERR_PTR(err);
|
|
}
|
|
/* Good, we have inserted empty locked entry into the tree. */
|
|
mapping->nrexceptional++;
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return entry;
|
|
}
|
|
entry = lock_slot(mapping, slot);
|
|
out_unlock:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return entry;
|
|
}
|
|
|
|
static int __dax_invalidate_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index, bool trunc)
|
|
{
|
|
int ret = 0;
|
|
void *entry;
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = get_unlocked_mapping_entry(mapping, index, NULL);
|
|
if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)))
|
|
goto out;
|
|
if (!trunc &&
|
|
(radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
|
|
radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)))
|
|
goto out;
|
|
radix_tree_delete(page_tree, index);
|
|
mapping->nrexceptional--;
|
|
ret = 1;
|
|
out:
|
|
put_unlocked_mapping_entry(mapping, index, entry);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return ret;
|
|
}
|
|
/*
|
|
* Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
|
|
* entry to get unlocked before deleting it.
|
|
*/
|
|
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
int ret = __dax_invalidate_mapping_entry(mapping, index, true);
|
|
|
|
/*
|
|
* This gets called from truncate / punch_hole path. As such, the caller
|
|
* must hold locks protecting against concurrent modifications of the
|
|
* radix tree (usually fs-private i_mmap_sem for writing). Since the
|
|
* caller has seen exceptional entry for this index, we better find it
|
|
* at that index as well...
|
|
*/
|
|
WARN_ON_ONCE(!ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Invalidate exceptional DAX entry if it is clean.
|
|
*/
|
|
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
|
|
pgoff_t index)
|
|
{
|
|
return __dax_invalidate_mapping_entry(mapping, index, false);
|
|
}
|
|
|
|
static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
|
|
sector_t sector, size_t size, struct page *to,
|
|
unsigned long vaddr)
|
|
{
|
|
void *vto, *kaddr;
|
|
pgoff_t pgoff;
|
|
pfn_t pfn;
|
|
long rc;
|
|
int id;
|
|
|
|
rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
|
|
if (rc)
|
|
return rc;
|
|
|
|
id = dax_read_lock();
|
|
rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
|
|
if (rc < 0) {
|
|
dax_read_unlock(id);
|
|
return rc;
|
|
}
|
|
vto = kmap_atomic(to);
|
|
copy_user_page(vto, (void __force *)kaddr, vaddr, to);
|
|
kunmap_atomic(vto);
|
|
dax_read_unlock(id);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* By this point grab_mapping_entry() has ensured that we have a locked entry
|
|
* of the appropriate size so we don't have to worry about downgrading PMDs to
|
|
* PTEs. If we happen to be trying to insert a PTE and there is a PMD
|
|
* already in the tree, we will skip the insertion and just dirty the PMD as
|
|
* appropriate.
|
|
*/
|
|
static void *dax_insert_mapping_entry(struct address_space *mapping,
|
|
struct vm_fault *vmf,
|
|
void *entry, sector_t sector,
|
|
unsigned long flags)
|
|
{
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
void *new_entry;
|
|
pgoff_t index = vmf->pgoff;
|
|
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
|
|
if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_ZERO_PAGE)) {
|
|
/* we are replacing a zero page with block mapping */
|
|
if (dax_is_pmd_entry(entry))
|
|
unmap_mapping_range(mapping,
|
|
(vmf->pgoff << PAGE_SHIFT) & PMD_MASK,
|
|
PMD_SIZE, 0);
|
|
else /* pte entry */
|
|
unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
|
|
PAGE_SIZE, 0);
|
|
}
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
new_entry = dax_radix_locked_entry(sector, flags);
|
|
|
|
if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
|
|
/*
|
|
* Only swap our new entry into the radix tree if the current
|
|
* entry is a zero page or an empty entry. If a normal PTE or
|
|
* PMD entry is already in the tree, we leave it alone. This
|
|
* means that if we are trying to insert a PTE and the
|
|
* existing entry is a PMD, we will just leave the PMD in the
|
|
* tree and dirty it if necessary.
|
|
*/
|
|
struct radix_tree_node *node;
|
|
void **slot;
|
|
void *ret;
|
|
|
|
ret = __radix_tree_lookup(page_tree, index, &node, &slot);
|
|
WARN_ON_ONCE(ret != entry);
|
|
__radix_tree_replace(page_tree, node, slot,
|
|
new_entry, NULL, NULL);
|
|
entry = new_entry;
|
|
}
|
|
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
|
|
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return entry;
|
|
}
|
|
|
|
static inline unsigned long
|
|
pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long address;
|
|
|
|
address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
|
|
VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
|
|
return address;
|
|
}
|
|
|
|
/* Walk all mappings of a given index of a file and writeprotect them */
|
|
static void dax_mapping_entry_mkclean(struct address_space *mapping,
|
|
pgoff_t index, unsigned long pfn)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
pte_t pte, *ptep = NULL;
|
|
pmd_t *pmdp = NULL;
|
|
spinlock_t *ptl;
|
|
|
|
i_mmap_lock_read(mapping);
|
|
vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
|
|
unsigned long address, start, end;
|
|
|
|
cond_resched();
|
|
|
|
if (!(vma->vm_flags & VM_SHARED))
|
|
continue;
|
|
|
|
address = pgoff_address(index, vma);
|
|
|
|
/*
|
|
* Note because we provide start/end to follow_pte_pmd it will
|
|
* call mmu_notifier_invalidate_range_start() on our behalf
|
|
* before taking any lock.
|
|
*/
|
|
if (follow_pte_pmd(vma->vm_mm, address, &start, &end, &ptep, &pmdp, &ptl))
|
|
continue;
|
|
|
|
if (pmdp) {
|
|
#ifdef CONFIG_FS_DAX_PMD
|
|
pmd_t pmd;
|
|
|
|
if (pfn != pmd_pfn(*pmdp))
|
|
goto unlock_pmd;
|
|
if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))
|
|
goto unlock_pmd;
|
|
|
|
flush_cache_page(vma, address, pfn);
|
|
pmd = pmdp_huge_clear_flush(vma, address, pmdp);
|
|
pmd = pmd_wrprotect(pmd);
|
|
pmd = pmd_mkclean(pmd);
|
|
set_pmd_at(vma->vm_mm, address, pmdp, pmd);
|
|
mmu_notifier_invalidate_range(vma->vm_mm, start, end);
|
|
unlock_pmd:
|
|
spin_unlock(ptl);
|
|
#endif
|
|
} else {
|
|
if (pfn != pte_pfn(*ptep))
|
|
goto unlock_pte;
|
|
if (!pte_dirty(*ptep) && !pte_write(*ptep))
|
|
goto unlock_pte;
|
|
|
|
flush_cache_page(vma, address, pfn);
|
|
pte = ptep_clear_flush(vma, address, ptep);
|
|
pte = pte_wrprotect(pte);
|
|
pte = pte_mkclean(pte);
|
|
set_pte_at(vma->vm_mm, address, ptep, pte);
|
|
mmu_notifier_invalidate_range(vma->vm_mm, start, end);
|
|
unlock_pte:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
|
|
}
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
static int dax_writeback_one(struct block_device *bdev,
|
|
struct dax_device *dax_dev, struct address_space *mapping,
|
|
pgoff_t index, void *entry)
|
|
{
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
void *entry2, **slot, *kaddr;
|
|
long ret = 0, id;
|
|
sector_t sector;
|
|
pgoff_t pgoff;
|
|
size_t size;
|
|
pfn_t pfn;
|
|
|
|
/*
|
|
* A page got tagged dirty in DAX mapping? Something is seriously
|
|
* wrong.
|
|
*/
|
|
if (WARN_ON(!radix_tree_exceptional_entry(entry)))
|
|
return -EIO;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
|
|
/* Entry got punched out / reallocated? */
|
|
if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2)))
|
|
goto put_unlocked;
|
|
/*
|
|
* Entry got reallocated elsewhere? No need to writeback. We have to
|
|
* compare sectors as we must not bail out due to difference in lockbit
|
|
* or entry type.
|
|
*/
|
|
if (dax_radix_sector(entry2) != dax_radix_sector(entry))
|
|
goto put_unlocked;
|
|
if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
|
|
dax_is_zero_entry(entry))) {
|
|
ret = -EIO;
|
|
goto put_unlocked;
|
|
}
|
|
|
|
/* Another fsync thread may have already written back this entry */
|
|
if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
|
|
goto put_unlocked;
|
|
/* Lock the entry to serialize with page faults */
|
|
entry = lock_slot(mapping, slot);
|
|
/*
|
|
* We can clear the tag now but we have to be careful so that concurrent
|
|
* dax_writeback_one() calls for the same index cannot finish before we
|
|
* actually flush the caches. This is achieved as the calls will look
|
|
* at the entry only under tree_lock and once they do that they will
|
|
* see the entry locked and wait for it to unlock.
|
|
*/
|
|
radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
|
|
/*
|
|
* Even if dax_writeback_mapping_range() was given a wbc->range_start
|
|
* in the middle of a PMD, the 'index' we are given will be aligned to
|
|
* the start index of the PMD, as will the sector we pull from
|
|
* 'entry'. This allows us to flush for PMD_SIZE and not have to
|
|
* worry about partial PMD writebacks.
|
|
*/
|
|
sector = dax_radix_sector(entry);
|
|
size = PAGE_SIZE << dax_radix_order(entry);
|
|
|
|
id = dax_read_lock();
|
|
ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
|
|
if (ret)
|
|
goto dax_unlock;
|
|
|
|
/*
|
|
* dax_direct_access() may sleep, so cannot hold tree_lock over
|
|
* its invocation.
|
|
*/
|
|
ret = dax_direct_access(dax_dev, pgoff, size / PAGE_SIZE, &kaddr, &pfn);
|
|
if (ret < 0)
|
|
goto dax_unlock;
|
|
|
|
if (WARN_ON_ONCE(ret < size / PAGE_SIZE)) {
|
|
ret = -EIO;
|
|
goto dax_unlock;
|
|
}
|
|
|
|
dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(pfn));
|
|
dax_flush(dax_dev, kaddr, size);
|
|
/*
|
|
* After we have flushed the cache, we can clear the dirty tag. There
|
|
* cannot be new dirty data in the pfn after the flush has completed as
|
|
* the pfn mappings are writeprotected and fault waits for mapping
|
|
* entry lock.
|
|
*/
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT);
|
|
dax_unlock:
|
|
dax_read_unlock(id);
|
|
put_locked_mapping_entry(mapping, index);
|
|
return ret;
|
|
|
|
put_unlocked:
|
|
put_unlocked_mapping_entry(mapping, index, entry2);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Flush the mapping to the persistent domain within the byte range of [start,
|
|
* end]. This is required by data integrity operations to ensure file data is
|
|
* on persistent storage prior to completion of the operation.
|
|
*/
|
|
int dax_writeback_mapping_range(struct address_space *mapping,
|
|
struct block_device *bdev, struct writeback_control *wbc)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
pgoff_t start_index, end_index;
|
|
pgoff_t indices[PAGEVEC_SIZE];
|
|
struct dax_device *dax_dev;
|
|
struct pagevec pvec;
|
|
bool done = false;
|
|
int i, ret = 0;
|
|
|
|
if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
|
|
return -EIO;
|
|
|
|
if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
|
|
return 0;
|
|
|
|
dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
|
|
if (!dax_dev)
|
|
return -EIO;
|
|
|
|
start_index = wbc->range_start >> PAGE_SHIFT;
|
|
end_index = wbc->range_end >> PAGE_SHIFT;
|
|
|
|
trace_dax_writeback_range(inode, start_index, end_index);
|
|
|
|
tag_pages_for_writeback(mapping, start_index, end_index);
|
|
|
|
pagevec_init(&pvec, 0);
|
|
while (!done) {
|
|
pvec.nr = find_get_entries_tag(mapping, start_index,
|
|
PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
|
|
pvec.pages, indices);
|
|
|
|
if (pvec.nr == 0)
|
|
break;
|
|
|
|
for (i = 0; i < pvec.nr; i++) {
|
|
if (indices[i] > end_index) {
|
|
done = true;
|
|
break;
|
|
}
|
|
|
|
ret = dax_writeback_one(bdev, dax_dev, mapping,
|
|
indices[i], pvec.pages[i]);
|
|
if (ret < 0) {
|
|
mapping_set_error(mapping, ret);
|
|
goto out;
|
|
}
|
|
}
|
|
start_index = indices[pvec.nr - 1] + 1;
|
|
}
|
|
out:
|
|
put_dax(dax_dev);
|
|
trace_dax_writeback_range_done(inode, start_index, end_index);
|
|
return (ret < 0 ? ret : 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
|
|
|
|
static int dax_insert_mapping(struct address_space *mapping,
|
|
struct block_device *bdev, struct dax_device *dax_dev,
|
|
sector_t sector, size_t size, void *entry,
|
|
struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
unsigned long vaddr = vmf->address;
|
|
void *ret, *kaddr;
|
|
pgoff_t pgoff;
|
|
int id, rc;
|
|
pfn_t pfn;
|
|
|
|
rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
|
|
if (rc)
|
|
return rc;
|
|
|
|
id = dax_read_lock();
|
|
rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
|
|
if (rc < 0) {
|
|
dax_read_unlock(id);
|
|
return rc;
|
|
}
|
|
dax_read_unlock(id);
|
|
|
|
ret = dax_insert_mapping_entry(mapping, vmf, entry, sector, 0);
|
|
if (IS_ERR(ret))
|
|
return PTR_ERR(ret);
|
|
|
|
trace_dax_insert_mapping(mapping->host, vmf, ret);
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
return vm_insert_mixed_mkwrite(vma, vaddr, pfn);
|
|
else
|
|
return vm_insert_mixed(vma, vaddr, pfn);
|
|
}
|
|
|
|
/*
|
|
* The user has performed a load from a hole in the file. Allocating a new
|
|
* page in the file would cause excessive storage usage for workloads with
|
|
* sparse files. Instead we insert a read-only mapping of the 4k zero page.
|
|
* If this page is ever written to we will re-fault and change the mapping to
|
|
* point to real DAX storage instead.
|
|
*/
|
|
static int dax_load_hole(struct address_space *mapping, void *entry,
|
|
struct vm_fault *vmf)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
unsigned long vaddr = vmf->address;
|
|
int ret = VM_FAULT_NOPAGE;
|
|
struct page *zero_page;
|
|
void *entry2;
|
|
|
|
zero_page = ZERO_PAGE(0);
|
|
if (unlikely(!zero_page)) {
|
|
ret = VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
|
|
entry2 = dax_insert_mapping_entry(mapping, vmf, entry, 0,
|
|
RADIX_DAX_ZERO_PAGE);
|
|
if (IS_ERR(entry2)) {
|
|
ret = VM_FAULT_SIGBUS;
|
|
goto out;
|
|
}
|
|
|
|
vm_insert_mixed(vmf->vma, vaddr, page_to_pfn_t(zero_page));
|
|
out:
|
|
trace_dax_load_hole(inode, vmf, ret);
|
|
return ret;
|
|
}
|
|
|
|
static bool dax_range_is_aligned(struct block_device *bdev,
|
|
unsigned int offset, unsigned int length)
|
|
{
|
|
unsigned short sector_size = bdev_logical_block_size(bdev);
|
|
|
|
if (!IS_ALIGNED(offset, sector_size))
|
|
return false;
|
|
if (!IS_ALIGNED(length, sector_size))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
int __dax_zero_page_range(struct block_device *bdev,
|
|
struct dax_device *dax_dev, sector_t sector,
|
|
unsigned int offset, unsigned int size)
|
|
{
|
|
if (dax_range_is_aligned(bdev, offset, size)) {
|
|
sector_t start_sector = sector + (offset >> 9);
|
|
|
|
return blkdev_issue_zeroout(bdev, start_sector,
|
|
size >> 9, GFP_NOFS, 0);
|
|
} else {
|
|
pgoff_t pgoff;
|
|
long rc, id;
|
|
void *kaddr;
|
|
pfn_t pfn;
|
|
|
|
rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
|
|
if (rc)
|
|
return rc;
|
|
|
|
id = dax_read_lock();
|
|
rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr,
|
|
&pfn);
|
|
if (rc < 0) {
|
|
dax_read_unlock(id);
|
|
return rc;
|
|
}
|
|
memset(kaddr + offset, 0, size);
|
|
dax_flush(dax_dev, kaddr + offset, size);
|
|
dax_read_unlock(id);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__dax_zero_page_range);
|
|
|
|
static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
|
|
{
|
|
return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
|
|
}
|
|
|
|
static loff_t
|
|
dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|
struct iomap *iomap)
|
|
{
|
|
struct block_device *bdev = iomap->bdev;
|
|
struct dax_device *dax_dev = iomap->dax_dev;
|
|
struct iov_iter *iter = data;
|
|
loff_t end = pos + length, done = 0;
|
|
ssize_t ret = 0;
|
|
int id;
|
|
|
|
if (iov_iter_rw(iter) == READ) {
|
|
end = min(end, i_size_read(inode));
|
|
if (pos >= end)
|
|
return 0;
|
|
|
|
if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
|
|
return iov_iter_zero(min(length, end - pos), iter);
|
|
}
|
|
|
|
if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
|
|
return -EIO;
|
|
|
|
/*
|
|
* Write can allocate block for an area which has a hole page mapped
|
|
* into page tables. We have to tear down these mappings so that data
|
|
* written by write(2) is visible in mmap.
|
|
*/
|
|
if (iomap->flags & IOMAP_F_NEW) {
|
|
invalidate_inode_pages2_range(inode->i_mapping,
|
|
pos >> PAGE_SHIFT,
|
|
(end - 1) >> PAGE_SHIFT);
|
|
}
|
|
|
|
id = dax_read_lock();
|
|
while (pos < end) {
|
|
unsigned offset = pos & (PAGE_SIZE - 1);
|
|
const size_t size = ALIGN(length + offset, PAGE_SIZE);
|
|
const sector_t sector = dax_iomap_sector(iomap, pos);
|
|
ssize_t map_len;
|
|
pgoff_t pgoff;
|
|
void *kaddr;
|
|
pfn_t pfn;
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
ret = -EINTR;
|
|
break;
|
|
}
|
|
|
|
ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
|
|
if (ret)
|
|
break;
|
|
|
|
map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
|
|
&kaddr, &pfn);
|
|
if (map_len < 0) {
|
|
ret = map_len;
|
|
break;
|
|
}
|
|
|
|
map_len = PFN_PHYS(map_len);
|
|
kaddr += offset;
|
|
map_len -= offset;
|
|
if (map_len > end - pos)
|
|
map_len = end - pos;
|
|
|
|
/*
|
|
* The userspace address for the memory copy has already been
|
|
* validated via access_ok() in either vfs_read() or
|
|
* vfs_write(), depending on which operation we are doing.
|
|
*/
|
|
if (iov_iter_rw(iter) == WRITE)
|
|
map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr,
|
|
map_len, iter);
|
|
else
|
|
map_len = copy_to_iter(kaddr, map_len, iter);
|
|
if (map_len <= 0) {
|
|
ret = map_len ? map_len : -EFAULT;
|
|
break;
|
|
}
|
|
|
|
pos += map_len;
|
|
length -= map_len;
|
|
done += map_len;
|
|
}
|
|
dax_read_unlock(id);
|
|
|
|
return done ? done : ret;
|
|
}
|
|
|
|
/**
|
|
* dax_iomap_rw - Perform I/O to a DAX file
|
|
* @iocb: The control block for this I/O
|
|
* @iter: The addresses to do I/O from or to
|
|
* @ops: iomap ops passed from the file system
|
|
*
|
|
* This function performs read and write operations to directly mapped
|
|
* persistent memory. The callers needs to take care of read/write exclusion
|
|
* and evicting any page cache pages in the region under I/O.
|
|
*/
|
|
ssize_t
|
|
dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct address_space *mapping = iocb->ki_filp->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
loff_t pos = iocb->ki_pos, ret = 0, done = 0;
|
|
unsigned flags = 0;
|
|
|
|
if (iov_iter_rw(iter) == WRITE) {
|
|
lockdep_assert_held_exclusive(&inode->i_rwsem);
|
|
flags |= IOMAP_WRITE;
|
|
} else {
|
|
lockdep_assert_held(&inode->i_rwsem);
|
|
}
|
|
|
|
while (iov_iter_count(iter)) {
|
|
ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
|
|
iter, dax_iomap_actor);
|
|
if (ret <= 0)
|
|
break;
|
|
pos += ret;
|
|
done += ret;
|
|
}
|
|
|
|
iocb->ki_pos += done;
|
|
return done ? done : ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_iomap_rw);
|
|
|
|
static int dax_fault_return(int error)
|
|
{
|
|
if (error == 0)
|
|
return VM_FAULT_NOPAGE;
|
|
if (error == -ENOMEM)
|
|
return VM_FAULT_OOM;
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
static int dax_iomap_pte_fault(struct vm_fault *vmf,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
unsigned long vaddr = vmf->address;
|
|
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
|
|
sector_t sector;
|
|
struct iomap iomap = { 0 };
|
|
unsigned flags = IOMAP_FAULT;
|
|
int error, major = 0;
|
|
int vmf_ret = 0;
|
|
void *entry;
|
|
|
|
trace_dax_pte_fault(inode, vmf, vmf_ret);
|
|
/*
|
|
* Check whether offset isn't beyond end of file now. Caller is supposed
|
|
* to hold locks serializing us with truncate / punch hole so this is
|
|
* a reliable test.
|
|
*/
|
|
if (pos >= i_size_read(inode)) {
|
|
vmf_ret = VM_FAULT_SIGBUS;
|
|
goto out;
|
|
}
|
|
|
|
if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
|
|
flags |= IOMAP_WRITE;
|
|
|
|
entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
|
|
if (IS_ERR(entry)) {
|
|
vmf_ret = dax_fault_return(PTR_ERR(entry));
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* It is possible, particularly with mixed reads & writes to private
|
|
* mappings, that we have raced with a PMD fault that overlaps with
|
|
* the PTE we need to set up. If so just return and the fault will be
|
|
* retried.
|
|
*/
|
|
if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) {
|
|
vmf_ret = VM_FAULT_NOPAGE;
|
|
goto unlock_entry;
|
|
}
|
|
|
|
/*
|
|
* Note that we don't bother to use iomap_apply here: DAX required
|
|
* the file system block size to be equal the page size, which means
|
|
* that we never have to deal with more than a single extent here.
|
|
*/
|
|
error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
|
|
if (error) {
|
|
vmf_ret = dax_fault_return(error);
|
|
goto unlock_entry;
|
|
}
|
|
if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
|
|
error = -EIO; /* fs corruption? */
|
|
goto error_finish_iomap;
|
|
}
|
|
|
|
sector = dax_iomap_sector(&iomap, pos);
|
|
|
|
if (vmf->cow_page) {
|
|
switch (iomap.type) {
|
|
case IOMAP_HOLE:
|
|
case IOMAP_UNWRITTEN:
|
|
clear_user_highpage(vmf->cow_page, vaddr);
|
|
break;
|
|
case IOMAP_MAPPED:
|
|
error = copy_user_dax(iomap.bdev, iomap.dax_dev,
|
|
sector, PAGE_SIZE, vmf->cow_page, vaddr);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
if (error)
|
|
goto error_finish_iomap;
|
|
|
|
__SetPageUptodate(vmf->cow_page);
|
|
vmf_ret = finish_fault(vmf);
|
|
if (!vmf_ret)
|
|
vmf_ret = VM_FAULT_DONE_COW;
|
|
goto finish_iomap;
|
|
}
|
|
|
|
switch (iomap.type) {
|
|
case IOMAP_MAPPED:
|
|
if (iomap.flags & IOMAP_F_NEW) {
|
|
count_vm_event(PGMAJFAULT);
|
|
count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
|
|
major = VM_FAULT_MAJOR;
|
|
}
|
|
error = dax_insert_mapping(mapping, iomap.bdev, iomap.dax_dev,
|
|
sector, PAGE_SIZE, entry, vmf->vma, vmf);
|
|
/* -EBUSY is fine, somebody else faulted on the same PTE */
|
|
if (error == -EBUSY)
|
|
error = 0;
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (!(vmf->flags & FAULT_FLAG_WRITE)) {
|
|
vmf_ret = dax_load_hole(mapping, entry, vmf);
|
|
goto finish_iomap;
|
|
}
|
|
/*FALLTHRU*/
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
error_finish_iomap:
|
|
vmf_ret = dax_fault_return(error) | major;
|
|
finish_iomap:
|
|
if (ops->iomap_end) {
|
|
int copied = PAGE_SIZE;
|
|
|
|
if (vmf_ret & VM_FAULT_ERROR)
|
|
copied = 0;
|
|
/*
|
|
* The fault is done by now and there's no way back (other
|
|
* thread may be already happily using PTE we have installed).
|
|
* Just ignore error from ->iomap_end since we cannot do much
|
|
* with it.
|
|
*/
|
|
ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
|
|
}
|
|
unlock_entry:
|
|
put_locked_mapping_entry(mapping, vmf->pgoff);
|
|
out:
|
|
trace_dax_pte_fault_done(inode, vmf, vmf_ret);
|
|
return vmf_ret;
|
|
}
|
|
|
|
#ifdef CONFIG_FS_DAX_PMD
|
|
static int dax_pmd_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
|
|
loff_t pos, void *entry)
|
|
{
|
|
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
|
const sector_t sector = dax_iomap_sector(iomap, pos);
|
|
struct dax_device *dax_dev = iomap->dax_dev;
|
|
struct block_device *bdev = iomap->bdev;
|
|
struct inode *inode = mapping->host;
|
|
const size_t size = PMD_SIZE;
|
|
void *ret = NULL, *kaddr;
|
|
long length = 0;
|
|
pgoff_t pgoff;
|
|
pfn_t pfn = {};
|
|
int id;
|
|
|
|
if (bdev_dax_pgoff(bdev, sector, size, &pgoff) != 0)
|
|
goto fallback;
|
|
|
|
id = dax_read_lock();
|
|
length = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
|
|
if (length < 0)
|
|
goto unlock_fallback;
|
|
length = PFN_PHYS(length);
|
|
|
|
if (length < size)
|
|
goto unlock_fallback;
|
|
if (pfn_t_to_pfn(pfn) & PG_PMD_COLOUR)
|
|
goto unlock_fallback;
|
|
if (!pfn_t_devmap(pfn))
|
|
goto unlock_fallback;
|
|
dax_read_unlock(id);
|
|
|
|
ret = dax_insert_mapping_entry(mapping, vmf, entry, sector,
|
|
RADIX_DAX_PMD);
|
|
if (IS_ERR(ret))
|
|
goto fallback;
|
|
|
|
trace_dax_pmd_insert_mapping(inode, vmf, length, pfn, ret);
|
|
return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
|
|
pfn, vmf->flags & FAULT_FLAG_WRITE);
|
|
|
|
unlock_fallback:
|
|
dax_read_unlock(id);
|
|
fallback:
|
|
trace_dax_pmd_insert_mapping_fallback(inode, vmf, length, pfn, ret);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
static int dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
|
|
void *entry)
|
|
{
|
|
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
|
unsigned long pmd_addr = vmf->address & PMD_MASK;
|
|
struct inode *inode = mapping->host;
|
|
struct page *zero_page;
|
|
void *ret = NULL;
|
|
spinlock_t *ptl;
|
|
pmd_t pmd_entry;
|
|
|
|
zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm);
|
|
|
|
if (unlikely(!zero_page))
|
|
goto fallback;
|
|
|
|
ret = dax_insert_mapping_entry(mapping, vmf, entry, 0,
|
|
RADIX_DAX_PMD | RADIX_DAX_ZERO_PAGE);
|
|
if (IS_ERR(ret))
|
|
goto fallback;
|
|
|
|
ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
|
|
if (!pmd_none(*(vmf->pmd))) {
|
|
spin_unlock(ptl);
|
|
goto fallback;
|
|
}
|
|
|
|
pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
|
|
pmd_entry = pmd_mkhuge(pmd_entry);
|
|
set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
|
|
spin_unlock(ptl);
|
|
trace_dax_pmd_load_hole(inode, vmf, zero_page, ret);
|
|
return VM_FAULT_NOPAGE;
|
|
|
|
fallback:
|
|
trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, ret);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
static int dax_iomap_pmd_fault(struct vm_fault *vmf,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
unsigned long pmd_addr = vmf->address & PMD_MASK;
|
|
bool write = vmf->flags & FAULT_FLAG_WRITE;
|
|
unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
|
|
struct inode *inode = mapping->host;
|
|
int result = VM_FAULT_FALLBACK;
|
|
struct iomap iomap = { 0 };
|
|
pgoff_t max_pgoff, pgoff;
|
|
void *entry;
|
|
loff_t pos;
|
|
int error;
|
|
|
|
/*
|
|
* Check whether offset isn't beyond end of file now. Caller is
|
|
* supposed to hold locks serializing us with truncate / punch hole so
|
|
* this is a reliable test.
|
|
*/
|
|
pgoff = linear_page_index(vma, pmd_addr);
|
|
max_pgoff = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
|
|
|
|
trace_dax_pmd_fault(inode, vmf, max_pgoff, 0);
|
|
|
|
/*
|
|
* Make sure that the faulting address's PMD offset (color) matches
|
|
* the PMD offset from the start of the file. This is necessary so
|
|
* that a PMD range in the page table overlaps exactly with a PMD
|
|
* range in the radix tree.
|
|
*/
|
|
if ((vmf->pgoff & PG_PMD_COLOUR) !=
|
|
((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR))
|
|
goto fallback;
|
|
|
|
/* Fall back to PTEs if we're going to COW */
|
|
if (write && !(vma->vm_flags & VM_SHARED))
|
|
goto fallback;
|
|
|
|
/* If the PMD would extend outside the VMA */
|
|
if (pmd_addr < vma->vm_start)
|
|
goto fallback;
|
|
if ((pmd_addr + PMD_SIZE) > vma->vm_end)
|
|
goto fallback;
|
|
|
|
if (pgoff >= max_pgoff) {
|
|
result = VM_FAULT_SIGBUS;
|
|
goto out;
|
|
}
|
|
|
|
/* If the PMD would extend beyond the file size */
|
|
if ((pgoff | PG_PMD_COLOUR) >= max_pgoff)
|
|
goto fallback;
|
|
|
|
/*
|
|
* grab_mapping_entry() will make sure we get a 2MiB empty entry, a
|
|
* 2MiB zero page entry or a DAX PMD. If it can't (because a 4k page
|
|
* is already in the tree, for instance), it will return -EEXIST and
|
|
* we just fall back to 4k entries.
|
|
*/
|
|
entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
|
|
if (IS_ERR(entry))
|
|
goto fallback;
|
|
|
|
/*
|
|
* It is possible, particularly with mixed reads & writes to private
|
|
* mappings, that we have raced with a PTE fault that overlaps with
|
|
* the PMD we need to set up. If so just return and the fault will be
|
|
* retried.
|
|
*/
|
|
if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) &&
|
|
!pmd_devmap(*vmf->pmd)) {
|
|
result = 0;
|
|
goto unlock_entry;
|
|
}
|
|
|
|
/*
|
|
* Note that we don't use iomap_apply here. We aren't doing I/O, only
|
|
* setting up a mapping, so really we're using iomap_begin() as a way
|
|
* to look up our filesystem block.
|
|
*/
|
|
pos = (loff_t)pgoff << PAGE_SHIFT;
|
|
error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
|
|
if (error)
|
|
goto unlock_entry;
|
|
|
|
if (iomap.offset + iomap.length < pos + PMD_SIZE)
|
|
goto finish_iomap;
|
|
|
|
switch (iomap.type) {
|
|
case IOMAP_MAPPED:
|
|
result = dax_pmd_insert_mapping(vmf, &iomap, pos, entry);
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (WARN_ON_ONCE(write))
|
|
break;
|
|
result = dax_pmd_load_hole(vmf, &iomap, entry);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
break;
|
|
}
|
|
|
|
finish_iomap:
|
|
if (ops->iomap_end) {
|
|
int copied = PMD_SIZE;
|
|
|
|
if (result == VM_FAULT_FALLBACK)
|
|
copied = 0;
|
|
/*
|
|
* The fault is done by now and there's no way back (other
|
|
* thread may be already happily using PMD we have installed).
|
|
* Just ignore error from ->iomap_end since we cannot do much
|
|
* with it.
|
|
*/
|
|
ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
|
|
&iomap);
|
|
}
|
|
unlock_entry:
|
|
put_locked_mapping_entry(mapping, pgoff);
|
|
fallback:
|
|
if (result == VM_FAULT_FALLBACK) {
|
|
split_huge_pmd(vma, vmf->pmd, vmf->address);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
}
|
|
out:
|
|
trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result);
|
|
return result;
|
|
}
|
|
#else
|
|
static int dax_iomap_pmd_fault(struct vm_fault *vmf,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
#endif /* CONFIG_FS_DAX_PMD */
|
|
|
|
/**
|
|
* dax_iomap_fault - handle a page fault on a DAX file
|
|
* @vmf: The description of the fault
|
|
* @ops: iomap ops passed from the file system
|
|
*
|
|
* When a page fault occurs, filesystems may call this helper in
|
|
* their fault handler for DAX files. dax_iomap_fault() assumes the caller
|
|
* has done all the necessary locking for page fault to proceed
|
|
* successfully.
|
|
*/
|
|
int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
switch (pe_size) {
|
|
case PE_SIZE_PTE:
|
|
return dax_iomap_pte_fault(vmf, ops);
|
|
case PE_SIZE_PMD:
|
|
return dax_iomap_pmd_fault(vmf, ops);
|
|
default:
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_iomap_fault);
|