From 7a42c70ea0dd56b3ed747c1fcf9b96cc26c77774 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 24 Oct 2019 22:26:27 -0700
Subject: [PATCH] xfs: disable xfs_ioc_space for always COW inodes

If we always have to write out of place preallocating blocks is
pointless.  We already check for this in the normal falloc path, but
the check was missig in the legacy ALLOCSP path.

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>
---
 fs/xfs/xfs_ioctl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index e897d5363d01..287f83eb791f 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -33,6 +33,7 @@
 #include "xfs_sb.h"
 #include "xfs_ag.h"
 #include "xfs_health.h"
+#include "xfs_reflink.h"
 
 #include <linux/mount.h>
 #include <linux/namei.h>
@@ -606,6 +607,9 @@ xfs_ioc_space(
 	if (!S_ISREG(inode->i_mode))
 		return -EINVAL;
 
+	if (xfs_is_always_cow_inode(ip))
+		return -EOPNOTSUPP;
+
 	if (filp->f_flags & O_DSYNC)
 		flags |= XFS_PREALLOC_SYNC;
 	if (filp->f_mode & FMODE_NOCMTIME)
-- 
2.20.1