diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 796a39a..950fc96 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -680,7 +680,7 @@
     }
 }
 
-bool ReadFstabFromFile(const std::string& path, Fstab* fstab) {
+bool ReadFstabFromFile(const std::string& path, Fstab* fstab_out) {
     auto fstab_file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
     if (!fstab_file) {
         PERROR << __FUNCTION__ << "(): cannot open file: '" << path << "'";
@@ -689,31 +689,43 @@
 
     bool is_proc_mounts = path == "/proc/mounts";
 
-    if (!ReadFstabFile(fstab_file.get(), is_proc_mounts, fstab)) {
+    Fstab fstab;
+    if (!ReadFstabFile(fstab_file.get(), is_proc_mounts, &fstab)) {
         LERROR << __FUNCTION__ << "(): failed to load fstab from : '" << path << "'";
         return false;
     }
-    if (!is_proc_mounts && !access(android::gsi::kGsiBootedIndicatorFile, F_OK)) {
-        // This is expected to fail if host is android Q, since Q doesn't
-        // support DSU slotting. The DSU "active" indicator file would be
-        // non-existent or empty if DSU is enabled within the guest system.
-        // In that case, just use the default slot name "dsu".
-        std::string dsu_slot;
-        if (!android::gsi::GetActiveDsu(&dsu_slot)) {
-            PWARNING << __FUNCTION__ << "(): failed to get active dsu slot";
+    if (!is_proc_mounts) {
+        if (!access(android::gsi::kGsiBootedIndicatorFile, F_OK)) {
+            // This is expected to fail if host is android Q, since Q doesn't
+            // support DSU slotting. The DSU "active" indicator file would be
+            // non-existent or empty if DSU is enabled within the guest system.
+            // In that case, just use the default slot name "dsu".
+            std::string dsu_slot;
+            if (!android::gsi::GetActiveDsu(&dsu_slot) && errno != ENOENT) {
+                PERROR << __FUNCTION__ << "(): failed to get active DSU slot";
+                return false;
+            }
+            if (dsu_slot.empty()) {
+                dsu_slot = "dsu";
+                LWARNING << __FUNCTION__ << "(): assuming default DSU slot: " << dsu_slot;
+            }
+            // This file is non-existent on Q vendor.
+            std::string lp_names;
+            if (!ReadFileToString(gsi::kGsiLpNamesFile, &lp_names) && errno != ENOENT) {
+                PERROR << __FUNCTION__ << "(): failed to read DSU LP names";
+                return false;
+            }
+            TransformFstabForDsu(&fstab, dsu_slot, Split(lp_names, ","));
+        } else if (errno != ENOENT) {
+            PERROR << __FUNCTION__ << "(): failed to access() DSU booted indicator";
+            return false;
         }
-        if (dsu_slot.empty()) {
-            dsu_slot = "dsu";
-        }
-
-        std::string lp_names;
-        ReadFileToString(gsi::kGsiLpNamesFile, &lp_names);
-        TransformFstabForDsu(fstab, dsu_slot, Split(lp_names, ","));
     }
 
-    SkipMountingPartitions(fstab, false /* verbose */);
-    EnableMandatoryFlags(fstab);
+    SkipMountingPartitions(&fstab, false /* verbose */);
+    EnableMandatoryFlags(&fstab);
 
+    *fstab_out = std::move(fstab);
     return true;
 }
 
@@ -788,10 +800,8 @@
 
 // Loads the fstab file and combines with fstab entries passed in from device tree.
 bool ReadDefaultFstab(Fstab* fstab) {
-    Fstab dt_fstab;
-    ReadFstabFromDt(&dt_fstab, false /* verbose */);
-
-    *fstab = std::move(dt_fstab);
+    fstab->clear();
+    ReadFstabFromDt(fstab, false /* verbose */);
 
     std::string default_fstab_path;
     // Use different fstab paths for normal boot and recovery boot, respectively
@@ -802,16 +812,14 @@
     }
 
     Fstab default_fstab;
-    if (!default_fstab_path.empty()) {
-        ReadFstabFromFile(default_fstab_path, &default_fstab);
+    if (!default_fstab_path.empty() && ReadFstabFromFile(default_fstab_path, &default_fstab)) {
+        for (auto&& entry : default_fstab) {
+            fstab->emplace_back(std::move(entry));
+        }
     } else {
         LINFO << __FUNCTION__ << "(): failed to find device default fstab";
     }
 
-    for (auto&& entry : default_fstab) {
-        fstab->emplace_back(std::move(entry));
-    }
-
     return !fstab->empty();
 }