xfs: rename the m_writeio_* fields in struct xfs_mount

Use the allocsize name to match the mount option and usage instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 271fcbe..382d727 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -514,7 +514,7 @@ xfs_stat_blksize(
 		if (mp->m_swidth)
 			return mp->m_swidth << mp->m_sb.sb_blocklog;
 		if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
-			return 1U << mp->m_writeio_log;
+			return 1U << mp->m_allocsize_log;
 	}
 
 	return PAGE_SIZE;