diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index b19b015769449c8f40ab75ce22f18b0ceec08220..c31ac96349d27d4a40b1fd3abceeb5a90aa97d4d 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -84,8 +84,6 @@ xfs_fs_geometry(
 				XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
 			(xfs_sb_version_hasdalign(&mp->m_sb) ?
 				XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
-			(xfs_sb_version_hasshared(&mp->m_sb) ?
-				XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
 			(xfs_sb_version_hasextflgbit(&mp->m_sb) ?
 				XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
 			(xfs_sb_version_hassector(&mp->m_sb) ?
diff --git a/fs/xfs/xfs_sb.c b/fs/xfs/xfs_sb.c
index de16dd558195f29b99dda9545f9c7a2e966edd52..c3453b11f5636d228cb5ceb433aa8c67e89c7709 100644
--- a/fs/xfs/xfs_sb.c
+++ b/fs/xfs/xfs_sb.c
@@ -291,7 +291,8 @@ xfs_mount_validate_sb(
 	    (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */)	||
 	    sbp->sb_dblocks == 0					||
 	    sbp->sb_dblocks > XFS_MAX_DBLOCKS(sbp)			||
-	    sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp))) {
+	    sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp)			||
+	    sbp->sb_shared_vn != 0)) {
 		xfs_notice(mp, "SB sanity check failed");
 		return XFS_ERROR(EFSCORRUPTED);
 	}
diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index 822e62819741752db7a2cc9f2a531f29d4a41ca7..86a964cc6925b2187589f3960d2c68601b88b97f 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -51,11 +51,12 @@ struct xfs_trans;
 
 /*
  * Supported feature bit list is just all bits in the versionnum field because
- * we've used them all up and understand them all.
+ * we've used them all up and understand them all. Except, of course, for the
+ * shared superblock bit, which nobody knows what it does and so is unsupported.
  */
 #define	XFS_SB_VERSION_OKBITS		\
-	(XFS_SB_VERSION_NUMBITS		| \
-	 XFS_SB_VERSION_ALLFBITS)
+	((XFS_SB_VERSION_NUMBITS | XFS_SB_VERSION_ALLFBITS) & \
+		~XFS_SB_VERSION_SHAREDBIT)
 
 /*
  * There are two words to hold XFS "feature" bits: the original
@@ -341,10 +342,6 @@ static inline bool xfs_sb_good_v4_features(struct xfs_sb *sbp)
 	     (sbp->sb_features2 & ~XFS_SB_VERSION2_OKBITS)))
 		return false;
 
-	/* We don't support shared superblocks - nobody knows what it is */
-	if (sbp->sb_versionnum & XFS_SB_VERSION_SHAREDBIT)
-		return false;
-
 	return true;
 }
 
@@ -397,12 +394,6 @@ static inline bool xfs_sb_version_hasdalign(struct xfs_sb *sbp)
 	return (sbp->sb_versionnum & XFS_SB_VERSION_DALIGNBIT);
 }
 
-static inline bool xfs_sb_version_hasshared(struct xfs_sb *sbp)
-{
-	return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_4 &&
-		(sbp->sb_versionnum & XFS_SB_VERSION_SHAREDBIT);
-}
-
 static inline bool xfs_sb_version_haslogv2(struct xfs_sb *sbp)
 {
 	return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 ||