+/*
+ * nobh_writepage() - based on block_full_write_page() except
+ * that it tries to operate without attaching bufferheads to
+ * the page.
+ */
+int nobh_writepage(struct page *page, get_block_t *get_block,
+ struct writeback_control *wbc)
+{
+ struct inode * const inode = page->mapping->host;
+ loff_t i_size = i_size_read(inode);
+ const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+ unsigned offset;
+ void *kaddr;
+ int ret;
+
+ /* Is the page fully inside i_size? */
+ if (page->index < end_index)
+ goto out;
+
+ /* Is the page fully outside i_size? (truncate in progress) */
+ offset = i_size & (PAGE_CACHE_SIZE-1);
+ if (page->index >= end_index+1 || !offset) {
+ /*
+ * The page may have dirty, unmapped buffers. For example,
+ * they may have been added in ext3_writepage(). Make them
+ * freeable here, so the page does not leak.
+ */
+#if 0
+ /* Not really sure about this - do we need this ? */
+ if (page->mapping->a_ops->invalidatepage)
+ page->mapping->a_ops->invalidatepage(page, offset);
+#endif
+ unlock_page(page);
+ return 0; /* don't care */
+ }
+
+ /*
+ * The page straddles i_size. It must be zeroed out on each and every
+ * writepage invocation because it may be mmapped. "A file is mapped
+ * in multiples of the page size. For a file that is not a multiple of
+ * the page size, the remaining memory is zeroed when mapped, and
+ * writes to that region are not written out to the file."
+ */
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+out:
+ ret = mpage_writepage(page, get_block, wbc);
+ if (ret == -EAGAIN)
+ ret = __block_write_full_page(inode, page, get_block, wbc);
+ return ret;
+}
+EXPORT_SYMBOL(nobh_writepage);
+