NTFS: Update __ntfs_index_entry_mark_dirty() so it makes sure that the

      page has buffers.  Otherwise we could end up with a dirty page
      without buffers and our set_page_dirty() would not mark the buffers
      dirty when they are created and thus they would not be written out
      and the dirty records would be lost.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/index.c

@@ -478,13 +478,15 @@ int ntfs_index_lookup(const void *key, const int key_len,
  */
 void __ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
 {
-	struct address_space *mapping;
-	struct page *page;
 	ntfs_inode *ni;
+	struct page *page;
+	struct buffer_head *bh, *head;
+	unsigned int rec_start, rec_end, bh_size, bh_start, bh_end;
 
 	BUG_ON(ictx->is_in_root);
 	ni = ictx->idx_ni;
 	page = ictx->page;
+	BUG_ON(!page_has_buffers(page));
 	/*
 	 * If the index block is the same size as the page cache page, set all
 	 * the buffers in the page, as well as the page itself, dirty.
@@ -494,24 +496,17 @@ void __ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
 		return;
 	}
 	/* Set only the buffers in which the index block is located dirty. */
-	mapping = page->mapping;
-	if (page_has_buffers(page)) {
-		struct buffer_head *bh, *head;
-		unsigned int bh_start, bh_end, rec_start, rec_end;
-		unsigned int bh_size = ni->vol->sb->s_blocksize;
-
-		bh = head = page_buffers(page);
-		bh_start = 0;
-		rec_start = (unsigned int)((u8*)ictx->ia -
-				(u8*)page_address(page));
-		rec_end = rec_start + ni->itype.index.block_size;
-		do {
-			bh_end = bh_start + bh_size;
-			if ((bh_start >= rec_start) && (bh_end <= rec_end))
-				set_buffer_dirty(bh);
-			bh_start = bh_end;
-		} while ((bh = bh->b_this_page) != head);
-	}
+	rec_start = (unsigned int)((u8*)ictx->ia - (u8*)page_address(page));
+	rec_end = rec_start + ni->itype.index.block_size;
+	bh_size = ni->vol->sb->s_blocksize;
+	bh_start = 0;
+	bh = head = page_buffers(page);
+	do {
+		bh_end = bh_start + bh_size;
+		if ((bh_start >= rec_start) && (bh_end <= rec_end))
+			set_buffer_dirty(bh);
+		bh_start = bh_end;
+	} while ((bh = bh->b_this_page) != head);
 	/* Finally, set the page itself dirty, too. */
 	__set_page_dirty_nobuffers(page);
 }