+static inline void
+ocfs2_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
+{
+ const struct iovec *iov = *iovp;
+ size_t base = *basep;
+
+ do {
+ int copy = min(bytes, iov->iov_len - base);
+
+ bytes -= copy;
+ base += copy;
+ if (iov->iov_len == base) {
+ iov++;
+ base = 0;
+ }
+ } while (bytes);
+ *iovp = iov;
+ *basep = base;
+}
+
+static struct page * ocfs2_get_write_source(struct ocfs2_buffered_write_priv *bp,
+ const struct iovec *cur_iov,
+ size_t iov_offset)
+{
+ int ret;
+ char *buf;
+ struct page *src_page = NULL;
+
+ buf = cur_iov->iov_base + iov_offset;
+
+ if (!segment_eq(get_fs(), KERNEL_DS)) {
+ /*
+ * Pull in the user page. We want to do this outside
+ * of the meta data locks in order to preserve locking
+ * order in case of page fault.
+ */
+ ret = get_user_pages(current, current->mm,
+ (unsigned long)buf & PAGE_CACHE_MASK, 1,
+ 0, 0, &src_page, NULL);
+ if (ret == 1)
+ bp->b_src_buf = kmap(src_page);
+ else
+ src_page = ERR_PTR(-EFAULT);
+ } else {
+ bp->b_src_buf = buf;
+ }
+
+ return src_page;
+}
+
+static void ocfs2_put_write_source(struct ocfs2_buffered_write_priv *bp,
+ struct page *page)
+{
+ if (page) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+}
+
+static ssize_t ocfs2_file_buffered_write(struct file *file, loff_t *ppos,
+ const struct iovec *iov,
+ unsigned long nr_segs,
+ size_t count,
+ ssize_t o_direct_written)
+{
+ int ret = 0;
+ ssize_t copied, total = 0;
+ size_t iov_offset = 0;
+ const struct iovec *cur_iov = iov;
+ struct ocfs2_buffered_write_priv bp;
+ struct page *page;
+
+ /*
+ * handle partial DIO write. Adjust cur_iov if needed.
+ */
+ ocfs2_set_next_iovec(&cur_iov, &iov_offset, o_direct_written);
+
+ do {
+ bp.b_cur_off = iov_offset;
+ bp.b_cur_iov = cur_iov;
+
+ page = ocfs2_get_write_source(&bp, cur_iov, iov_offset);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto out;
+ }
+
+ copied = ocfs2_buffered_write_cluster(file, *ppos, count,
+ ocfs2_map_and_write_user_data,
+ &bp);
+
+ ocfs2_put_write_source(&bp, page);
+
+ if (copied < 0) {
+ mlog_errno(copied);
+ ret = copied;
+ goto out;
+ }
+
+ total += copied;
+ *ppos = *ppos + copied;
+ count -= copied;
+
+ ocfs2_set_next_iovec(&cur_iov, &iov_offset, copied);
+ } while(count);
+
+out:
+ return total ? total : ret;
+}
+