diff options
| -rw-r--r-- | fs/dax.c | 22 |
1 files changed, 19 insertions, 3 deletions
@@ -353,16 +353,27 @@ static struct page *dax_busy_page(void *entry) return NULL; } +/* + * 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: %true if the entry was locked or does not need to be locked. + */ bool dax_lock_mapping_entry(struct page *page) { XA_STATE(xas, NULL, 0); void *entry; + bool locked; + /* Ensure page->mapping isn't freed while we look at it */ + rcu_read_lock(); for (;;) { struct address_space *mapping = READ_ONCE(page->mapping); + locked = false; if (!dax_mapping(mapping)) - return false; + break; /* * In the device-dax case there's no need to lock, a @@ -371,8 +382,9 @@ bool dax_lock_mapping_entry(struct page *page) * otherwise we would not have a valid pfn_to_page() * translation. */ + locked = true; if (S_ISCHR(mapping->host->i_mode)) - return true; + break; xas.xa = &mapping->i_pages; xas_lock_irq(&xas); @@ -383,14 +395,18 @@ bool dax_lock_mapping_entry(struct page *page) xas_set(&xas, page->index); entry = xas_load(&xas); if (dax_is_locked(entry)) { + rcu_read_unlock(); entry = get_unlocked_entry(&xas); xas_unlock_irq(&xas); + rcu_read_lock(); continue; } dax_lock_entry(&xas, entry); xas_unlock_irq(&xas); - return true; + break; } + rcu_read_unlock(); + return locked; } void dax_unlock_mapping_entry(struct page *page) |