diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index a97369a..35f8be8 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -41,14 +41,18 @@
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
 #include <ext4_utils/ext4_utils.h>
+#include <fs_mgr_dm_linear.h>
 #include <fs_mgr_overlayfs.h>
 #include <fstab/fstab.h>
 #include <libdm/dm.h>
+#include <liblp/builder.h>
+#include <liblp/liblp.h>
 
 #include "fs_mgr_priv.h"
 
 using namespace std::literals;
 using namespace android::dm;
+using namespace android::fs_mgr;
 
 #if ALLOW_ADBD_DISABLE_VERITY == 0  // If we are a user build, provide stubs
 
@@ -74,8 +78,10 @@
 
 namespace {
 
-// acceptable overlayfs backing storage
-const auto kOverlayMountPoint = "/cache"s;
+// list of acceptable overlayfs backing storage
+const auto kScratchMountPoint = "/mnt/scratch"s;
+const auto kCacheMountPoint = "/cache"s;
+const std::vector<const std::string> kOverlayMountPoints = {kScratchMountPoint, kCacheMountPoint};
 
 // Return true if everything is mounted, but before adb is started.  Right
 // after 'trigger load_persist_props_action' is done.
@@ -136,14 +142,17 @@
 
 std::string fs_mgr_get_overlayfs_candidate(const std::string& mount_point) {
     if (!fs_mgr_is_dir(mount_point)) return "";
-    auto dir =
-            kOverlayMountPoint + kOverlayTopDir + "/" + android::base::Basename(mount_point) + "/";
-    auto upper = dir + kUpperName;
-    if (!fs_mgr_is_dir(upper)) return "";
-    auto work = dir + kWorkName;
-    if (!fs_mgr_is_dir(work)) return "";
-    if (!fs_mgr_dir_is_writable(work)) return "";
-    return dir;
+    const auto base = android::base::Basename(mount_point) + "/";
+    for (const auto& overlay_mount_point : kOverlayMountPoints) {
+        auto dir = overlay_mount_point + kOverlayTopDir + "/" + base;
+        auto upper = dir + kUpperName;
+        if (!fs_mgr_is_dir(upper)) continue;
+        auto work = dir + kWorkName;
+        if (!fs_mgr_is_dir(work)) continue;
+        if (!fs_mgr_dir_is_writable(work)) continue;
+        return dir;
+    }
+    return "";
 }
 
 const auto kLowerdirOption = "lowerdir="s;
@@ -187,6 +196,14 @@
     return ret;
 }
 
+bool fs_mgr_rw_access(const std::string& path) {
+    if (path.empty()) return false;
+    auto save_errno = errno;
+    auto ret = access(path.c_str(), R_OK | W_OK) == 0;
+    errno = save_errno;
+    return ret;
+}
+
 // return true if system supports overlayfs
 bool fs_mgr_wants_overlayfs() {
     // Properties will return empty on init first_stage_mount, so speculative
@@ -200,7 +217,7 @@
     return fs_mgr_access("/sys/module/overlay/parameters/override_creds");
 }
 
-bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point) {
+bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true) {
     std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab("/proc/mounts"),
                                                                fs_mgr_free_fstab);
     if (!fstab) return false;
@@ -209,10 +226,11 @@
         const auto fsrec = &fstab->recs[i];
         const auto fs_type = fsrec->fs_type;
         if (!fs_type) continue;
-        if (("overlay"s != fs_type) && ("overlayfs"s != fs_type)) continue;
+        if (overlay_only && ("overlay"s != fs_type) && ("overlayfs"s != fs_type)) continue;
         auto fsrec_mount_point = fsrec->mount_point;
         if (!fsrec_mount_point) continue;
         if (mount_point != fsrec_mount_point) continue;
+        if (!overlay_only) return true;
         const auto fs_options = fsrec->fs_options;
         if (!fs_options) continue;
         const auto options = android::base::Split(fs_options, ",");
@@ -373,6 +391,67 @@
     return ret;
 }
 
+uint32_t fs_mgr_overlayfs_slot_number() {
+    return SlotNumberForSlotSuffix(fs_mgr_get_slot_suffix());
+}
+
+std::string fs_mgr_overlayfs_super_device(uint32_t slot_number) {
+    return "/dev/block/by-name/" + fs_mgr_get_super_partition_name(slot_number);
+}
+
+bool fs_mgr_overlayfs_has_logical(const fstab* fstab) {
+    if (!fstab) return false;
+    for (auto i = 0; i < fstab->num_entries; i++) {
+        const auto fsrec = &fstab->recs[i];
+        if (fs_mgr_is_logical(fsrec)) return true;
+    }
+    return false;
+}
+
+// reduce 'DM_DEV_STATUS failed for scratch: No such device or address' noise
+std::string scratch_device_cache;
+
+bool fs_mgr_overlayfs_teardown_scratch(const std::string& overlay, bool* change) {
+    // umount and delete kScratchMountPoint storage if we have logical partitions
+    if (overlay != kScratchMountPoint) return true;
+    scratch_device_cache.erase();
+    auto slot_number = fs_mgr_overlayfs_slot_number();
+    auto super_device = fs_mgr_overlayfs_super_device(slot_number);
+    if (!fs_mgr_rw_access(super_device)) return true;
+
+    auto save_errno = errno;
+    if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
+        // Lazy umount will allow us to move on and possibly later
+        // establish a new fresh mount without requiring a reboot should
+        // the developer wish to restart.  Old references should melt
+        // away or have no data.  Main goal is to shut the door on the
+        // current overrides with an expectation of a subsequent reboot,
+        // thus any errors here are ignored.
+        umount2(kScratchMountPoint.c_str(), MNT_DETACH);
+    }
+    auto builder = MetadataBuilder::New(super_device, slot_number);
+    if (!builder) {
+        errno = save_errno;
+        return true;
+    }
+    const auto partition_name = android::base::Basename(kScratchMountPoint);
+    if (builder->FindPartition(partition_name) == nullptr) {
+        errno = save_errno;
+        return true;
+    }
+    builder->RemovePartition(partition_name);
+    auto metadata = builder->Export();
+    if (metadata && UpdatePartitionTable(super_device, *metadata.get(), slot_number)) {
+        if (change) *change = true;
+        if (!DestroyLogicalPartition(partition_name, 0s)) return false;
+    } else {
+        PERROR << "delete partition " << overlay;
+        return false;
+    }
+    errno = save_errno;
+    return true;
+}
+
 bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string& mount_point,
                                    bool* change) {
     const auto top = overlay + kOverlayTopDir;
@@ -406,13 +485,16 @@
         save_errno = errno;
         if (!rmdir(top.c_str())) {
             if (change) *change = true;
+            cleanup_all = true;
         } else if ((errno != ENOENT) && (errno != ENOTEMPTY)) {
             ret = false;
             PERROR << "rmdir " << top;
         } else {
             errno = save_errno;
+            cleanup_all = true;
         }
     }
+    if (cleanup_all) ret &= fs_mgr_overlayfs_teardown_scratch(overlay, change);
     return ret;
 }
 
@@ -504,6 +586,138 @@
     return mounts;
 }
 
+// Mount kScratchMountPoint
+bool fs_mgr_overlayfs_mount_scratch(const std::string& device_path, const std::string mnt_type) {
+    if (setfscreatecon(kOverlayfsFileContext)) {
+        PERROR << "setfscreatecon " << kOverlayfsFileContext;
+    }
+    if (mkdir(kScratchMountPoint.c_str(), 0755) && (errno != EEXIST)) {
+        PERROR << "create " << kScratchMountPoint;
+    }
+
+    std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> local_fstab(
+            static_cast<fstab*>(calloc(1, sizeof(fstab))), fs_mgr_free_fstab);
+    auto fsrec = static_cast<fstab_rec*>(calloc(1, sizeof(fstab_rec)));
+    local_fstab->num_entries = 1;
+    local_fstab->recs = fsrec;
+    fsrec->blk_device = strdup(device_path.c_str());
+    fsrec->mount_point = strdup(kScratchMountPoint.c_str());
+    fsrec->fs_type = strdup(mnt_type.c_str());
+    fsrec->flags = MS_RELATIME;
+    fsrec->fs_options = strdup("");
+    auto mounted = fs_mgr_do_mount_one(fsrec) == 0;
+    auto save_errno = errno;
+    setfscreatecon(nullptr);
+    if (!mounted) rmdir(kScratchMountPoint.c_str());
+    errno = save_errno;
+    return mounted;
+}
+
+const std::string kMkF2fs("/system/bin/make_f2fs");
+const std::string kMkExt4("/system/bin/mke2fs");
+
+std::string fs_mgr_overlayfs_scratch_mount_type() {
+    if (!access(kMkF2fs.c_str(), X_OK)) return "f2fs";
+    if (!access(kMkExt4.c_str(), X_OK)) return "ext4";
+    return "auto";
+}
+
+std::string fs_mgr_overlayfs_scratch_device() {
+    if (!scratch_device_cache.empty()) return scratch_device_cache;
+
+    auto& dm = DeviceMapper::Instance();
+    const auto partition_name = android::base::Basename(kScratchMountPoint);
+    std::string path;
+    if (!dm.GetDmDevicePathByName(partition_name, &path)) return "";
+    return scratch_device_cache = path;
+}
+
+// Create and mount kScratchMountPoint storage if we have logical partitions
+bool fs_mgr_overlayfs_setup_scratch(const fstab* fstab, bool* change) {
+    if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) return true;
+    auto mnt_type = fs_mgr_overlayfs_scratch_mount_type();
+    auto scratch_device = fs_mgr_overlayfs_scratch_device();
+    auto partition_exists = fs_mgr_rw_access(scratch_device);
+    if (!partition_exists) {
+        auto slot_number = fs_mgr_overlayfs_slot_number();
+        auto super_device = fs_mgr_overlayfs_super_device(slot_number);
+        if (!fs_mgr_rw_access(super_device)) return false;
+        if (!fs_mgr_overlayfs_has_logical(fstab)) return false;
+        auto builder = MetadataBuilder::New(super_device, slot_number);
+        if (!builder) {
+            PERROR << "open " << super_device << " metadata";
+            return false;
+        }
+        const auto partition_name = android::base::Basename(kScratchMountPoint);
+        partition_exists = builder->FindPartition(partition_name) != nullptr;
+        if (!partition_exists) {
+            auto partition = builder->AddPartition(partition_name, LP_PARTITION_ATTR_NONE);
+            if (!partition) {
+                PERROR << "create " << partition_name;
+                return false;
+            }
+            auto partition_size = builder->AllocatableSpace() - builder->UsedSpace();
+            // 512MB or half the remaining available space, whichever is greater.
+            partition_size = std::max(uint64_t(512 * 1024 * 1024), partition_size / 2);
+            if (!builder->ResizePartition(partition, partition_size)) {
+                PERROR << "resize " << partition_name;
+                return false;
+            }
+
+            auto metadata = builder->Export();
+            if (!metadata) {
+                LERROR << "generate new metadata " << partition_name;
+                return false;
+            }
+            if (!UpdatePartitionTable(super_device, *metadata.get(), slot_number)) {
+                LERROR << "update " << partition_name;
+                return false;
+            }
+
+            if (change) *change = true;
+        }
+
+        if (!CreateLogicalPartition(super_device, slot_number, partition_name, true, 0s,
+                                    &scratch_device))
+            return false;
+    }
+
+    if (partition_exists) {
+        if (fs_mgr_overlayfs_mount_scratch(scratch_device, mnt_type)) {
+            if (change) *change = true;
+            return true;
+        }
+        // partition existed, but was not initialized;
+        errno = 0;
+    }
+
+    auto ret = system((mnt_type == "f2fs")
+                              ? ((kMkF2fs + " -d1 " + scratch_device).c_str())
+                              : ((kMkExt4 + " -b 4096 -t ext4 -m 0 -M "s + kScratchMountPoint +
+                                  " -O has_journal " + scratch_device)
+                                         .c_str()));
+    if (ret) {
+        LERROR << "make " << mnt_type << " filesystem on " << scratch_device << " error=" << ret;
+        return false;
+    }
+
+    if (change) *change = true;
+
+    return fs_mgr_overlayfs_mount_scratch(scratch_device, mnt_type);
+}
+
+bool fs_mgr_overlayfs_scratch_can_be_mounted(const std::string& scratch_device) {
+    if (scratch_device.empty()) return false;
+    if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) return false;
+    if (fs_mgr_rw_access(scratch_device)) return true;
+    auto slot_number = fs_mgr_overlayfs_slot_number();
+    auto super_device = fs_mgr_overlayfs_super_device(slot_number);
+    if (!fs_mgr_rw_access(super_device)) return false;
+    auto builder = MetadataBuilder::New(super_device, slot_number);
+    if (!builder) return false;
+    return builder->FindPartition(android::base::Basename(kScratchMountPoint)) != nullptr;
+}
+
 }  // namespace
 
 bool fs_mgr_overlayfs_mount_all(const fstab* fstab) {
@@ -513,14 +727,37 @@
 
     if (!fstab) return ret;
 
+    auto scratch_can_be_mounted = true;
     for (const auto& mount_point : fs_mgr_candidate_list(fstab)) {
         if (fs_mgr_overlayfs_already_mounted(mount_point)) continue;
+        if (scratch_can_be_mounted) {
+            scratch_can_be_mounted = false;
+            auto scratch_device = fs_mgr_overlayfs_scratch_device();
+            if (fs_mgr_overlayfs_scratch_can_be_mounted(scratch_device) &&
+                fs_mgr_wait_for_file(scratch_device, 10s) &&
+                fs_mgr_overlayfs_mount_scratch(scratch_device,
+                                               fs_mgr_overlayfs_scratch_mount_type()) &&
+                !fs_mgr_access(kScratchMountPoint + kOverlayTopDir)) {
+                umount2(kScratchMountPoint.c_str(), MNT_DETACH);
+                rmdir(kScratchMountPoint.c_str());
+            }
+        }
         if (fs_mgr_overlayfs_mount(mount_point)) ret = true;
     }
     return ret;
 }
 
-std::vector<std::string> fs_mgr_overlayfs_required_devices(const fstab*) {
+std::vector<std::string> fs_mgr_overlayfs_required_devices(const fstab* fstab) {
+    if (fs_mgr_get_entry_for_mount_point(const_cast<struct fstab*>(fstab), kScratchMountPoint)) {
+        return {};
+    }
+
+    for (const auto& mount_point : fs_mgr_candidate_list(fstab)) {
+        if (fs_mgr_overlayfs_already_mounted(mount_point)) continue;
+        auto device = fs_mgr_overlayfs_scratch_device();
+        if (!fs_mgr_overlayfs_scratch_can_be_mounted(device)) break;
+        return {device};
+    }
     return {};
 }
 
@@ -529,10 +766,6 @@
 bool fs_mgr_overlayfs_setup(const char* backing, const char* mount_point, bool* change) {
     if (change) *change = false;
     auto ret = false;
-    if (backing && (kOverlayMountPoint != backing)) {
-        errno = EINVAL;
-        return ret;
-    }
     if (!fs_mgr_wants_overlayfs()) return ret;
     if (!fs_mgr_boot_completed()) {
         errno = EBUSY;
@@ -542,16 +775,32 @@
 
     std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
                                                                fs_mgr_free_fstab);
-    if (fstab && !fs_mgr_get_entry_for_mount_point(fstab.get(), kOverlayMountPoint)) return ret;
+    if (!fstab) return ret;
     auto mounts = fs_mgr_candidate_list(fstab.get(), fs_mgr_mount_point(fstab.get(), mount_point));
-    if (fstab && mounts.empty()) return ret;
+    if (mounts.empty()) return ret;
+
+    std::string dir;
+    for (const auto& overlay_mount_point : kOverlayMountPoints) {
+        if (backing && backing[0] && (overlay_mount_point != backing)) continue;
+        if (overlay_mount_point == kScratchMountPoint) {
+            if (!fs_mgr_rw_access(fs_mgr_overlayfs_super_device(fs_mgr_overlayfs_slot_number())) ||
+                !fs_mgr_overlayfs_has_logical(fstab.get())) {
+                continue;
+            }
+            if (!fs_mgr_overlayfs_setup_scratch(fstab.get(), change)) continue;
+        } else {
+            if (!fs_mgr_get_entry_for_mount_point(fstab.get(), overlay_mount_point)) continue;
+        }
+        dir = overlay_mount_point;
+        break;
+    }
+    if (dir.empty()) {
+        errno = ESRCH;
+        return ret;
+    }
 
     std::string overlay;
-    ret |= fs_mgr_overlayfs_setup_dir(kOverlayMountPoint, &overlay, change);
-
-    if (!fstab && mount_point && fs_mgr_overlayfs_setup_one(overlay, mount_point, change)) {
-        ret = true;
-    }
+    ret |= fs_mgr_overlayfs_setup_dir(dir, &overlay, change);
     for (const auto& fsrec_mount_point : mounts) {
         ret |= fs_mgr_overlayfs_setup_one(overlay, fsrec_mount_point, change);
     }
@@ -566,7 +815,10 @@
                                              fs_mgr_read_fstab_default(), fs_mgr_free_fstab)
                                              .get(),
                                      mount_point);
-    auto ret = fs_mgr_overlayfs_teardown_one(kOverlayMountPoint, mount_point ?: "", change);
+    auto ret = true;
+    for (const auto& overlay_mount_point : kOverlayMountPoints) {
+        ret &= fs_mgr_overlayfs_teardown_one(overlay_mount_point, mount_point ?: "", change);
+    }
     if (!fs_mgr_wants_overlayfs()) {
         // After obligatory teardown to make sure everything is clean, but if
         // we didn't want overlayfs in the the first place, we do not want to
diff --git a/fs_mgr/fs_mgr_priv.h b/fs_mgr/fs_mgr_priv.h
index 506e81d..5e83cfb 100644
--- a/fs_mgr/fs_mgr_priv.h
+++ b/fs_mgr/fs_mgr_priv.h
@@ -128,10 +128,10 @@
                           FileWaitMode wait_mode = FileWaitMode::Exists);
 
 int fs_mgr_set_blk_ro(const char* blockdev);
-bool fs_mgr_update_for_slotselect(struct fstab *fstab);
+bool fs_mgr_update_for_slotselect(fstab* fstab);
 bool fs_mgr_is_device_unlocked();
 const std::string& get_android_dt_dir();
 bool is_dt_compatible();
-int load_verity_state(struct fstab_rec* fstab, int* mode);
+int load_verity_state(fstab_rec* fstab, int* mode);
 
 #endif /* __CORE_FS_MGR_PRIV_H */
diff --git a/fs_mgr/include/fs_mgr.h b/fs_mgr/include/fs_mgr.h
index a4544b2..5dabe76 100644
--- a/fs_mgr/include/fs_mgr.h
+++ b/fs_mgr/include/fs_mgr.h
@@ -51,8 +51,8 @@
 };
 
 // Callback function for verity status
-typedef void fs_mgr_verity_state_callback(struct fstab_rec* fstab, const char* mount_point,
-                                          int mode, int status);
+typedef void fs_mgr_verity_state_callback(fstab_rec* fstab, const char* mount_point, int mode,
+                                          int status);
 
 #define FS_MGR_MNTALL_DEV_IS_METADATA_ENCRYPTED 7
 #define FS_MGR_MNTALL_DEV_NEEDS_METADATA_ENCRYPTION 6
@@ -63,32 +63,31 @@
 #define FS_MGR_MNTALL_DEV_NOT_ENCRYPTED 1
 #define FS_MGR_MNTALL_DEV_NOT_ENCRYPTABLE 0
 #define FS_MGR_MNTALL_FAIL (-1)
-int fs_mgr_mount_all(struct fstab *fstab, int mount_mode);
+int fs_mgr_mount_all(fstab* fstab, int mount_mode);
 
 #define FS_MGR_DOMNT_FAILED (-1)
 #define FS_MGR_DOMNT_BUSY (-2)
 #define FS_MGR_DOMNT_SUCCESS 0
 
-int fs_mgr_do_mount(struct fstab *fstab, const char *n_name, char *n_blk_device,
-                    char *tmp_mount_point);
-int fs_mgr_do_mount(struct fstab* fstab, const char* n_name, char* n_blk_device,
-                    char* tmp_mount_point, bool need_cp);
-int fs_mgr_do_mount_one(struct fstab_rec *rec);
+int fs_mgr_do_mount(fstab* fstab, const char* n_name, char* n_blk_device, char* tmp_mount_point);
+int fs_mgr_do_mount(fstab* fstab, const char* n_name, char* n_blk_device, char* tmp_mount_point,
+                    bool need_cp);
+int fs_mgr_do_mount_one(fstab_rec* rec);
 int fs_mgr_do_tmpfs_mount(const char *n_name);
-struct fstab_rec const* fs_mgr_get_crypt_entry(struct fstab const* fstab);
-void fs_mgr_get_crypt_info(struct fstab* fstab, char* key_loc, char* real_blk_device, size_t size);
+fstab_rec const* fs_mgr_get_crypt_entry(fstab const* fstab);
+void fs_mgr_get_crypt_info(fstab* fstab, char* key_loc, char* real_blk_device, size_t size);
 bool fs_mgr_load_verity_state(int* mode);
 bool fs_mgr_update_verity_state(std::function<fs_mgr_verity_state_callback> callback);
 int fs_mgr_swapon_all(struct fstab *fstab);
 bool fs_mgr_update_logical_partition(struct fstab_rec* rec);
 
-int fs_mgr_do_format(struct fstab_rec *fstab, bool reserve_footer);
+int fs_mgr_do_format(fstab_rec* fstab, bool reserve_footer);
 
 #define FS_MGR_SETUP_VERITY_SKIPPED  (-3)
 #define FS_MGR_SETUP_VERITY_DISABLED (-2)
 #define FS_MGR_SETUP_VERITY_FAIL (-1)
 #define FS_MGR_SETUP_VERITY_SUCCESS 0
-int fs_mgr_setup_verity(struct fstab_rec *fstab, bool wait_for_verity_dev);
+int fs_mgr_setup_verity(fstab_rec* fstab, bool wait_for_verity_dev);
 
 // Return the name of the super partition if it exists. If a slot number is
 // specified, the super partition for the corresponding metadata slot will be