1 files changed, 22 insertions, 1 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 4fd6b0c5c6b5..fc2e3141138b 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -58,6 +58,26 @@ static void dax_unmap_atomic(struct block_device *bdev,
         blk_queue_exit(bdev->bd_queue);
 }
 
+struct page *read_dax_sector(struct block_device *bdev, sector_t n)
+{
+        struct page *page = alloc_pages(GFP_KERNEL, 0);
+        struct blk_dax_ctl dax = {
+                .size = PAGE_SIZE,
+                .sector = n & ~((((int) PAGE_SIZE) / 512) - 1),
+        };
+        long rc;
+
+        if (!page)
+                return ERR_PTR(-ENOMEM);
+
+        rc = dax_map_atomic(bdev, &dax);
+        if (rc < 0)
+                return ERR_PTR(rc);
+        memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE);
+        dax_unmap_atomic(bdev, &dax);
+        return page;
+}
+
 /*
  * dax_clear_blocks() is called from within transaction context from XFS,
  * and hence this means the stack from this point must follow GFP_NOFS
@@ -338,7 +358,8 @@ static int dax_radix_entry(struct address_space *mapping, pgoff_t index,
         void *entry;
 
         WARN_ON_ONCE(pmd_entry && !dirty);
-        __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+        if (dirty)
+                __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 
         spin_lock_irq(&mapping->tree_lock);