xfs: factor out dir2 data block reading

And add a verifier callback function while there.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Phil White <pwhite@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
diff --git a/fs/xfs/xfs_dir2_data.c b/fs/xfs/xfs_dir2_data.c
index cb11723..0ef04f1 100644
--- a/fs/xfs/xfs_dir2_data.c
+++ b/fs/xfs/xfs_dir2_data.c
@@ -185,6 +185,38 @@
 	return 0;
 }
 
+static void
+xfs_dir2_data_verify(
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = bp->b_target->bt_mount;
+	struct xfs_dir2_data_hdr *hdr = bp->b_addr;
+	int			block_ok = 0;
+
+	block_ok = hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC);
+	block_ok = block_ok && __xfs_dir2_data_check(NULL, bp) == 0;
+
+	if (!block_ok) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, hdr);
+		xfs_buf_ioerror(bp, EFSCORRUPTED);
+	}
+
+	bp->b_iodone = NULL;
+	xfs_buf_ioend(bp, 0);
+}
+
+int
+xfs_dir2_data_read(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	xfs_dablk_t		bno,
+	xfs_daddr_t		mapped_bno,
+	struct xfs_buf		**bpp)
+{
+	return xfs_da_read_buf(tp, dp, bno, mapped_bno, bpp,
+					XFS_DATA_FORK, xfs_dir2_data_verify);
+}
+
 /*
  * Given a data block and an unused entry from that block,
  * return the bestfree entry if any that corresponds to it.