1 files changed, 70 insertions, 0 deletions
diff --git a/fs/libfs.c b/fs/libfs.c
index 7124c2e8df2f..d1c3bade9f30 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1451,4 +1451,74 @@ int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
 	return 0;
 }
 EXPORT_SYMBOL(generic_ci_d_hash);
+
+static const struct dentry_operations generic_ci_dentry_ops = {
+	.d_hash = generic_ci_d_hash,
+	.d_compare = generic_ci_d_compare,
+};
+#endif
+
+#ifdef CONFIG_FS_ENCRYPTION
+static const struct dentry_operations generic_encrypted_dentry_ops = {
+	.d_revalidate = fscrypt_d_revalidate,
+};
+#endif
+
+#if defined(CONFIG_FS_ENCRYPTION) && defined(CONFIG_UNICODE)
+static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
+	.d_hash = generic_ci_d_hash,
+	.d_compare = generic_ci_d_compare,
+	.d_revalidate = fscrypt_d_revalidate,
+};
+#endif
+
+/**
+ * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
+ * @dentry:	dentry to set ops on
+ *
+ * Casefolded directories need d_hash and d_compare set, so that the dentries
+ * contained in them are handled case-insensitively.  Note that these operations
+ * are needed on the parent directory rather than on the dentries in it, and
+ * while the casefolding flag can be toggled on and off on an empty directory,
+ * dentry_operations can't be changed later.  As a result, if the filesystem has
+ * casefolding support enabled at all, we have to give all dentries the
+ * casefolding operations even if their inode doesn't have the casefolding flag
+ * currently (and thus the casefolding ops would be no-ops for now).
+ *
+ * Encryption works differently in that the only dentry operation it needs is
+ * d_revalidate, which it only needs on dentries that have the no-key name flag.
+ * The no-key flag can't be set "later", so we don't have to worry about that.
+ *
+ * Finally, to maximize compatibility with overlayfs (which isn't compatible
+ * with certain dentry operations) and to avoid taking an unnecessary
+ * performance hit, we use custom dentry_operations for each possible
+ * combination rather than always installing all operations.
+ */
+void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
+{
+#ifdef CONFIG_FS_ENCRYPTION
+	bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
+#endif
+#ifdef CONFIG_UNICODE
+	bool needs_ci_ops = dentry->d_sb->s_encoding;
+#endif
+#if defined(CONFIG_FS_ENCRYPTION) && defined(CONFIG_UNICODE)
+	if (needs_encrypt_ops && needs_ci_ops) {
+		d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
+		return;
+	}
 #endif
+#ifdef CONFIG_FS_ENCRYPTION
+	if (needs_encrypt_ops) {
+		d_set_d_op(dentry, &generic_encrypted_dentry_ops);
+		return;
+	}
+#endif
+#ifdef CONFIG_UNICODE
+	if (needs_ci_ops) {
+		d_set_d_op(dentry, &generic_ci_dentry_ops);
+		return;
+	}
+#endif
+}
+EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);