xfs: Remove the macro XFS_BUF_ERROR and family

Remove the definitions and usage of the macros XFS_BUF_ERROR,
XFS_BUF_GETERROR and XFS_BUF_ISERROR.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
diff --git a/fs/xfs/xfs_rw.c b/fs/xfs/xfs_rw.c
index d6d6fdf..d1f76f8 100644
--- a/fs/xfs/xfs_rw.c
+++ b/fs/xfs/xfs_rw.c
@@ -106,7 +106,7 @@
 		 "       (\"%s\") error %d buf count %zd",
 		XFS_BUFTARG_NAME(XFS_BUF_TARGET(bp)),
 		(__uint64_t)blkno, func,
-		XFS_BUF_GETERROR(bp), XFS_BUF_COUNT(bp));
+		bp->b_error, XFS_BUF_COUNT(bp));
 }
 
 /*
@@ -137,8 +137,8 @@
 	bp = xfs_buf_read(target, blkno, len, flags);
 	if (!bp)
 		return XFS_ERROR(EIO);
-	error = XFS_BUF_GETERROR(bp);
-	if (bp && !error && !XFS_FORCED_SHUTDOWN(mp)) {
+	error = bp->b_error;
+	if (!error && !XFS_FORCED_SHUTDOWN(mp)) {
 		*bpp = bp;
 	} else {
 		*bpp = NULL;