ext4: filesystems without casefold feature cannot be mounted with siphash

commit 985b67c upstream.

When mounting the ext4 filesystem, if the default hash version is set to
DX_HASH_SIPHASH but the casefold feature is not set, exit the mounting.

Reported-by: [email protected]
Signed-off-by: Lizhi Xu <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
[cascardo: small conflict fixup]
Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit 52c4538a92da6f3242d4140c03ddc5ee71b39ba8)
Signed-off-by: Wentao Guan <[email protected]>

Author: Lizhi Xu

fs/ext4/super.c

@@ -3639,6 +3639,14 @@ int ext4_feature_set_ok(struct super_block *sb, int readonly)
 	}
 #endif
 
+	if (EXT4_SB(sb)->s_es->s_def_hash_version == DX_HASH_SIPHASH &&
+	    !ext4_has_feature_casefold(sb)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Filesystem without casefold feature cannot be "
+			 "mounted with siphash");
+		return 0;
+	}
+
 	if (readonly)
 		return 1;