xfs: Add XFS_SB_FEAT_INCOMPAT_NREXT64 to the list of supported flags

This commit enables XFS module to work with fs instances having 64-bit
per-inode extent counters by adding XFS_SB_FEAT_INCOMPAT_NREXT64 flag to the
list of supported incompat feature flags.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>

fs/xfs/libxfs/xfs_format.h

@@ -378,7 +378,8 @@ xfs_sb_has_ro_compat_feature(
 		 XFS_SB_FEAT_INCOMPAT_SPINODES|	\
 		 XFS_SB_FEAT_INCOMPAT_META_UUID| \
 		 XFS_SB_FEAT_INCOMPAT_BIGTIME| \
-		 XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR)
+		 XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR| \
+		 XFS_SB_FEAT_INCOMPAT_NREXT64)
 
 #define XFS_SB_FEAT_INCOMPAT_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_ALL
 static inline bool

fs/xfs/xfs_super.c

@@ -1639,6 +1639,10 @@ xfs_fs_fill_super(
 		goto out_filestream_unmount;
 	}
 
+	if (xfs_has_large_extent_counts(mp))
+		xfs_warn(mp,
+	"EXPERIMENTAL Large extent counts feature in use. Use at your own risk!");
+
 	error = xfs_mountfs(mp);
 	if (error)
 		goto out_filestream_unmount;