diff --git a/cmds/installd/QuotaUtils.cpp b/cmds/installd/QuotaUtils.cpp
new file mode 100644
index 0000000..b238dd3
--- /dev/null
+++ b/cmds/installd/QuotaUtils.cpp
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "QuotaUtils.h"
+
+#include <fstream>
+#include <unordered_map>
+
+#include <sys/quota.h>
+
+#include <android-base/logging.h>
+
+#include "utils.h"
+
+namespace android {
+namespace installd {
+
+namespace {
+
+std::recursive_mutex mMountsLock;
+
+/* Map of all quota mounts from target to source */
+std::unordered_map<std::string, std::string> mQuotaReverseMounts;
+
+std::string& FindQuotaDeviceForUuid(const std::string& uuid) {
+    std::lock_guard<std::recursive_mutex> lock(mMountsLock);
+    auto path = create_data_path(uuid.empty() ? nullptr : uuid.c_str());
+    return mQuotaReverseMounts[path];
+}
+
+} // namespace
+
+bool InvalidateQuotaMounts() {
+    std::lock_guard<std::recursive_mutex> lock(mMountsLock);
+
+    mQuotaReverseMounts.clear();
+
+    std::ifstream in("/proc/mounts");
+    if (!in.is_open()) {
+        return false;
+    }
+
+    std::string source;
+    std::string target;
+    std::string ignored;
+    while (!in.eof()) {
+        std::getline(in, source, ' ');
+        std::getline(in, target, ' ');
+        std::getline(in, ignored);
+
+        if (source.compare(0, 11, "/dev/block/") == 0) {
+            struct dqblk dq;
+            if (quotactl(QCMD(Q_GETQUOTA, USRQUOTA), source.c_str(), 0,
+                    reinterpret_cast<char*>(&dq)) == 0) {
+                LOG(DEBUG) << "Found quota mount " << source << " at " << target;
+                mQuotaReverseMounts[target] = source;
+            }
+        }
+    }
+    return true;
+}
+
+bool IsQuotaSupported(const std::string& uuid) {
+    return !FindQuotaDeviceForUuid(uuid).empty();
+}
+
+int64_t GetOccupiedSpaceForUid(const std::string& uuid, uid_t uid) {
+    const std::string device = FindQuotaDeviceForUuid(uuid);
+    if (device == "") {
+        return -1;
+    }
+    struct dqblk dq;
+    if (quotactl(QCMD(Q_GETQUOTA, USRQUOTA), device.c_str(), uid,
+            reinterpret_cast<char*>(&dq)) != 0) {
+        if (errno != ESRCH) {
+            PLOG(ERROR) << "Failed to quotactl " << device << " for UID " << uid;
+        }
+        return -1;
+    } else {
+#if MEASURE_DEBUG
+        LOG(DEBUG) << "quotactl() for UID " << uid << " " << dq.dqb_curspace;
+#endif
+        return dq.dqb_curspace;
+    }
+}
+
+int64_t GetOccupiedSpaceForGid(const std::string& uuid, gid_t gid) {
+    const std::string device = FindQuotaDeviceForUuid(uuid);
+    if (device == "") {
+        return -1;
+    }
+    struct dqblk dq;
+    if (quotactl(QCMD(Q_GETQUOTA, GRPQUOTA), device.c_str(), gid,
+            reinterpret_cast<char*>(&dq)) != 0) {
+        if (errno != ESRCH) {
+            PLOG(ERROR) << "Failed to quotactl " << device << " for GID " << gid;
+        }
+        return -1;
+    } else {
+#if MEASURE_DEBUG
+        LOG(DEBUG) << "quotactl() for GID " << gid << " " << dq.dqb_curspace;
+#endif
+        return dq.dqb_curspace;
+    }
+
+}
+
+}  // namespace installd
+}  // namespace android