From: "Luis R. Rodriguez" <mcgrof@suse.com>
Subject: [PATCH] xfs: extend unsupported annotations: reflink or reverse
 mapping btree
References: FATE#324503
Patch-mainline: Never, SUSE-specific

Reflink support is not yet ready for prime time upstream.
Neither is reverse mapping btree support.

So only allow read-only mount on these, unless a user loads the
module with allow_unsupported=1.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
---
 fs/xfs/xfs_super.c |   29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -61,6 +61,10 @@
 #include <linux/kthread.h>
 #include <linux/freezer.h>
 #include <linux/parser.h>
+#include <linux/unsupported-feature.h>
+
+DECLARE_SUSE_UNSUPPORTED_FEATURE(xfs);
+DEFINE_SUSE_UNSUPPORTED_FEATURE(xfs);
 
 static const struct super_operations xfs_super_operations;
 struct bio_set *xfs_ioend_bioset;
@@ -1547,6 +1551,20 @@ xfs_destroy_percpu_counters(
 	percpu_counter_destroy(&mp->m_fdblocks);
 }
 
+int
+xfs_check_unsupported(struct xfs_mount *mp, const char *description)
+{
+	if (mp->m_flags & XFS_MOUNT_RDONLY)
+		return 0;
+
+	if (xfs_allow_unsupported())
+		return 0;
+
+	xfs_alert(mp, "Couldn't mount because of unsupported optional feature %s.  Load module with allow_unsupported=1.",
+		  description);
+	return -EOPNOTSUPP;
+}
+
 STATIC int
 xfs_fs_fill_super(
 	struct super_block	*sb,
@@ -1642,8 +1660,6 @@ xfs_fs_fill_super(
 	if (mp->m_flags & XFS_MOUNT_DAX) {
 		bool rtdev_is_dax = false, datadev_is_dax;
 
-		xfs_warn(mp,
-		"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
 
 		datadev_is_dax = bdev_dax_supported(mp->m_ddev_targp->bt_bdev,
 			sb->s_blocksize);
@@ -1667,13 +1683,20 @@ xfs_fs_fill_super(
 			error = -EINVAL;
 			goto out_filestream_unmount;
 		}
+		error = xfs_check_unsupported(mp, "EXPERIMENTAL reverse mapping btree");
+		if (error)
+			goto out_filestream_unmount;
 		xfs_alert(mp,
 	"EXPERIMENTAL reverse mapping btree feature enabled. Use at your own risk!");
 	}
 
-	if (xfs_sb_version_hasreflink(&mp->m_sb))
+	if (xfs_sb_version_hasreflink(&mp->m_sb))  {
+		error = xfs_check_unsupported(mp, "EXPERIMENTAL reflink support");
+		if (error)
+			goto out_filestream_unmount;
 		xfs_alert(mp,
 	"EXPERIMENTAL reflink feature enabled. Use at your own risk!");
+	}
 
 	if (xfs_sb_version_hasinobtcounts(&mp->m_sb))
 		xfs_warn(mp,