[PATCH 4.4 106/112] ext4: do not advertise encryption support when disabled

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@xxxxxxxxxx>

commit c4704a4fbe834eee4109ca064131d440941f6235 upstream.

The sysfs file /sys/fs/ext4/features/encryption was present on kernels
compiled with CONFIG_EXT4_FS_ENCRYPTION=n.  This was misleading because
such kernels do not actually support ext4 encryption.  Therefore, only
provide this file on kernels compiled with CONFIG_EXT4_FS_ENCRYPTION=y.

Note: since the ext4 feature files are all hardcoded to have a contents
of "supported", it really is the presence or absence of the file that is
significant, not the contents (and this change reflects that).

Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ext4/sysfs.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -223,14 +223,18 @@ static struct attribute *ext4_attrs[] =
 EXT4_ATTR_FEATURE(lazy_itable_init);
 EXT4_ATTR_FEATURE(batched_discard);
 EXT4_ATTR_FEATURE(meta_bg_resize);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
 EXT4_ATTR_FEATURE(encryption);
+#endif
 EXT4_ATTR_FEATURE(metadata_csum_seed);
 
 static struct attribute *ext4_feat_attrs[] = {
 	ATTR_LIST(lazy_itable_init),
 	ATTR_LIST(batched_discard),
 	ATTR_LIST(meta_bg_resize),
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
 	ATTR_LIST(encryption),
+#endif
 	ATTR_LIST(metadata_csum_seed),
 	NULL,
 };