f2fs: Advertise encrypted casefolding in sysfs

Older kernels don't support encryption with casefolding. This adds
the sysfs entry encrypted_casefold to show support for those combined
features. Support for this feature was originally added by
commit 7ad08a58 ("f2fs: Handle casefolding with Encryption")

Fixes: 7ad08a58 ("f2fs: Handle casefolding with Encryption")
Cc: stable@vger.kernel.org # v5.11+
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/sysfs.c

@@ -583,6 +583,7 @@ enum feat_id {
 	FEAT_COMPRESSION,
 	FEAT_RO,
 	FEAT_TEST_DUMMY_ENCRYPTION_V2,
+	FEAT_ENCRYPTED_CASEFOLD,
 };
 
 static ssize_t f2fs_feature_show(struct f2fs_attr *a,
@@ -605,6 +606,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
 	case FEAT_COMPRESSION:
 	case FEAT_RO:
 	case FEAT_TEST_DUMMY_ENCRYPTION_V2:
+	case FEAT_ENCRYPTED_CASEFOLD:
 		return sprintf(buf, "supported\n");
 	}
 	return 0;
@@ -709,7 +711,10 @@ F2FS_GENERAL_RO_ATTR(avg_vblocks);
 #ifdef CONFIG_FS_ENCRYPTION
 F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO);
 F2FS_FEATURE_RO_ATTR(test_dummy_encryption_v2, FEAT_TEST_DUMMY_ENCRYPTION_V2);
+#ifdef CONFIG_UNICODE
+F2FS_FEATURE_RO_ATTR(encrypted_casefold, FEAT_ENCRYPTED_CASEFOLD);
 #endif
+#endif /* CONFIG_FS_ENCRYPTION */
 #ifdef CONFIG_BLK_DEV_ZONED
 F2FS_FEATURE_RO_ATTR(block_zoned, FEAT_BLKZONED);
 #endif
@@ -822,7 +827,10 @@ static struct attribute *f2fs_feat_attrs[] = {
 #ifdef CONFIG_FS_ENCRYPTION
 	ATTR_LIST(encryption),
 	ATTR_LIST(test_dummy_encryption_v2),
+#ifdef CONFIG_UNICODE
+	ATTR_LIST(encrypted_casefold),
 #endif
+#endif /* CONFIG_FS_ENCRYPTION */
 #ifdef CONFIG_BLK_DEV_ZONED
 	ATTR_LIST(block_zoned),
 #endif