return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT));
}
-static void *dax_make_page_entry(struct page *page)
-{
- pfn_t pfn = page_to_pfn_t(page);
- return dax_make_entry(pfn, PageHead(page) ? DAX_PMD : 0);
-}
-
static bool dax_is_locked(void *entry)
{
return xa_to_value(entry) & DAX_LOCKED;
return 0;
}
-static int dax_is_pmd_entry(void *entry)
+static unsigned long dax_is_pmd_entry(void *entry)
{
return xa_to_value(entry) & DAX_PMD;
}
-static int dax_is_pte_entry(void *entry)
+static bool dax_is_pte_entry(void *entry)
{
return !(xa_to_value(entry) & DAX_PMD);
}
ewait.wait.func = wake_exceptional_entry_func;
for (;;) {
- entry = xas_load(xas);
- if (!entry || xa_is_internal(entry) ||
- WARN_ON_ONCE(!xa_is_value(entry)) ||
+ entry = xas_find_conflict(xas);
+ if (!entry || WARN_ON_ONCE(!xa_is_value(entry)) ||
!dax_is_locked(entry))
return entry;
}
}
+/*
+ * The only thing keeping the address space around is the i_pages lock
+ * (it's cycled in clear_inode() after removing the entries from i_pages)
+ * After we call xas_unlock_irq(), we cannot touch xas->xa.
+ */
+static void wait_entry_unlocked(struct xa_state *xas, void *entry)
+{
+ struct wait_exceptional_entry_queue ewait;
+ wait_queue_head_t *wq;
+
+ init_wait(&ewait.wait);
+ ewait.wait.func = wake_exceptional_entry_func;
+
+ wq = dax_entry_waitqueue(xas, entry, &ewait.key);
+ /*
+ * Unlike get_unlocked_entry() there is no guarantee that this
+ * path ever successfully retrieves an unlocked entry before an
+ * inode dies. Perform a non-exclusive wait in case this path
+ * never successfully performs its own wake up.
+ */
+ prepare_to_wait(wq, &ewait.wait, TASK_UNINTERRUPTIBLE);
+ xas_unlock_irq(xas);
+ schedule();
+ finish_wait(wq, &ewait.wait);
+}
+
static void put_unlocked_entry(struct xa_state *xas, void *entry)
{
/* If we were the only waiter woken, wake the next one */
{
void *old;
+ BUG_ON(dax_is_locked(entry));
xas_reset(xas);
xas_lock_irq(xas);
old = xas_store(xas, entry);
return NULL;
}
-bool dax_lock_mapping_entry(struct page *page)
+/*
+ * dax_lock_mapping_entry - Lock the DAX entry corresponding to a page
+ * @page: The page whose entry we want to lock
+ *
+ * Context: Process context.
+ * Return: A cookie to pass to dax_unlock_page() or 0 if the entry could
+ * not be locked.
+ */
+dax_entry_t dax_lock_page(struct page *page)
{
XA_STATE(xas, NULL, 0);
void *entry;
+ /* Ensure page->mapping isn't freed while we look at it */
+ rcu_read_lock();
for (;;) {
struct address_space *mapping = READ_ONCE(page->mapping);
- if (!dax_mapping(mapping))
- return false;
+ entry = NULL;
+ if (!mapping || !dax_mapping(mapping))
+ break;
/*
* In the device-dax case there's no need to lock, a
* otherwise we would not have a valid pfn_to_page()
* translation.
*/
+ entry = (void *)~0UL;
if (S_ISCHR(mapping->host->i_mode))
- return true;
+ break;
xas.xa = &mapping->i_pages;
xas_lock_irq(&xas);
xas_set(&xas, page->index);
entry = xas_load(&xas);
if (dax_is_locked(entry)) {
- entry = get_unlocked_entry(&xas);
- /* Did the page move while we slept? */
- if (dax_to_pfn(entry) != page_to_pfn(page)) {
- xas_unlock_irq(&xas);
- continue;
- }
+ rcu_read_unlock();
+ wait_entry_unlocked(&xas, entry);
+ rcu_read_lock();
+ continue;
}
dax_lock_entry(&xas, entry);
xas_unlock_irq(&xas);
- return true;
+ break;
}
+ rcu_read_unlock();
+ return (dax_entry_t)entry;
}
-void dax_unlock_mapping_entry(struct page *page)
+void dax_unlock_page(struct page *page, dax_entry_t cookie)
{
struct address_space *mapping = page->mapping;
XA_STATE(xas, &mapping->i_pages, page->index);
if (S_ISCHR(mapping->host->i_mode))
return;
- dax_unlock_entry(&xas, dax_make_page_entry(page));
+ dax_unlock_entry(&xas, (void *)cookie);
}
/*
retry:
xas_lock_irq(xas);
entry = get_unlocked_entry(xas);
- if (xa_is_internal(entry))
- goto fallback;
if (entry) {
- if (WARN_ON_ONCE(!xa_is_value(entry))) {
+ if (!xa_is_value(entry)) {
xas_set_err(xas, EIO);
goto out_unlock;
}
i_mmap_lock_read(mapping);
vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
- unsigned long address, start, end;
+ struct mmu_notifier_range range;
+ unsigned long address;
cond_resched();
* 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))
+ if (follow_pte_pmd(vma->vm_mm, address, &range,
+ &ptep, &pmdp, &ptl))
continue;
/*
pte_unmap_unlock(ptep, ptl);
}
- mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
+ mmu_notifier_invalidate_range_end(&range);
}
i_mmap_unlock_read(mapping);
}
/* Did we race with someone splitting entry or so? */
if (!entry ||
(order == 0 && !dax_is_pte_entry(entry)) ||
- (order == PMD_ORDER && (xa_is_internal(entry) ||
- !dax_is_pmd_entry(entry)))) {
+ (order == PMD_ORDER && !dax_is_pmd_entry(entry))) {
put_unlocked_entry(&xas, entry);
xas_unlock_irq(&xas);
trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
projects / linux-2.6-block.git / blobdiff