diff options
| -rw-r--r-- | fs/dax.c | 83 |
1 files changed, 35 insertions, 48 deletions
@@ -99,6 +99,17 @@ static void *dax_make_locked(unsigned long pfn, unsigned long flags) DAX_LOCKED); } +static void *dax_make_entry(pfn_t pfn, unsigned long flags) +{ + 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; @@ -487,33 +498,16 @@ static struct page *dax_busy_page(void *entry) return NULL; } -static bool entry_wait_revalidate(void) -{ - rcu_read_unlock(); - schedule(); - rcu_read_lock(); - - /* - * Tell __get_unlocked_mapping_entry() to take a break, we need - * to revalidate page->mapping after dropping locks - */ - return true; -} - bool dax_lock_mapping_entry(struct page *page) { - pgoff_t index; - struct inode *inode; - bool did_lock = false; - void *entry = NULL, **slot; - struct address_space *mapping; + XA_STATE(xas, NULL, 0); + void *entry; - rcu_read_lock(); for (;;) { - mapping = READ_ONCE(page->mapping); + struct address_space *mapping = READ_ONCE(page->mapping); if (!dax_mapping(mapping)) - break; + return false; /* * In the device-dax case there's no need to lock, a @@ -522,47 +516,40 @@ bool dax_lock_mapping_entry(struct page *page) * otherwise we would not have a valid pfn_to_page() * translation. */ - inode = mapping->host; - if (S_ISCHR(inode->i_mode)) { - did_lock = true; - break; - } + if (S_ISCHR(mapping->host->i_mode)) + return true; - xa_lock_irq(&mapping->i_pages); + xas.xa = &mapping->i_pages; + xas_lock_irq(&xas); if (mapping != page->mapping) { - xa_unlock_irq(&mapping->i_pages); + xas_unlock_irq(&xas); continue; } - index = page->index; - - entry = __get_unlocked_mapping_entry(mapping, index, &slot, - entry_wait_revalidate); - if (!entry) { - xa_unlock_irq(&mapping->i_pages); - break; - } else if (IS_ERR(entry)) { - WARN_ON_ONCE(PTR_ERR(entry) != -EAGAIN); - continue; + 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; + } } - lock_slot(mapping, slot); - did_lock = true; - xa_unlock_irq(&mapping->i_pages); - break; + dax_lock_entry(&xas, entry); + xas_unlock_irq(&xas); + return true; } - rcu_read_unlock(); - - return did_lock; } void dax_unlock_mapping_entry(struct page *page) { struct address_space *mapping = page->mapping; - struct inode *inode = mapping->host; + XA_STATE(xas, &mapping->i_pages, page->index); - if (S_ISCHR(inode->i_mode)) + if (S_ISCHR(mapping->host->i_mode)) return; - unlock_mapping_entry(mapping, page->index); + dax_unlock_entry(&xas, dax_make_page_entry(page)); } /* |