3 files changed, 34 insertions, 2 deletions

diff --git a/recovery_main.cpp b/recovery_main.cpp
index 78350944c..19ef4f3d0 100644
--- a/recovery_main.cpp
+++ b/recovery_main.cpp
@@ -478,8 +478,13 @@ int main(int argc, char** argv) {
         break;
 
       case Device::ENTER_FASTBOOT:
-        LOG(INFO) << "Entering fastboot";
-        fastboot = true;
+        if (logical_partitions_mapped()) {
+          ui->Print("Partitions may be mounted - rebooting to enter fastboot.");
+          android::base::SetProperty(ANDROID_RB_PROPERTY, "reboot,fastboot");
+        } else {
+          LOG(INFO) << "Entering fastboot";
+          fastboot = true;
+        }
         break;
 
       case Device::ENTER_RECOVERY:
diff --git a/roots.cpp b/roots.cpp
index c29771af6..dc347848a 100644
--- a/roots.cpp
+++ b/roots.cpp
@@ -38,10 +38,12 @@
 #include <cryptfs.h>
 #include <ext4_utils/wipe.h>
 #include <fs_mgr.h>
+#include <fs_mgr_dm_linear.h>
 
 #include "otautil/mounts.h"
 
 static struct fstab* fstab = nullptr;
+static bool did_map_logical_partitions = false;
 
 extern struct selabel_handle* sehandle;
 
@@ -117,6 +119,25 @@ int ensure_path_mounted_at(const char* path, const char* mount_point) {
     mount_point = v->mount_point;
   }
 
+  // If we can't acquire the block device for a logical partition, it likely
+  // was never created. In that case we try to create it.
+  if (fs_mgr_is_logical(v) && !fs_mgr_update_logical_partition(v)) {
+    if (did_map_logical_partitions) {
+      LOG(ERROR) << "Failed to find block device for partition";
+      return -1;
+    }
+    std::string super_name = fs_mgr_get_super_partition_name();
+    if (!android::fs_mgr::CreateLogicalPartitions(super_name)) {
+      LOG(ERROR) << "Failed to create logical partitions";
+      return -1;
+    }
+    did_map_logical_partitions = true;
+    if (!fs_mgr_update_logical_partition(v)) {
+      LOG(ERROR) << "Failed to find block device for partition";
+      return -1;
+    }
+  }
+
   const MountedVolume* mv = find_mounted_volume_by_mount_point(mount_point);
   if (mv != nullptr) {
     // Volume is already mounted.
@@ -387,3 +408,7 @@ int setup_install_mounts() {
   }
   return 0;
 }
+
+bool logical_partitions_mapped() {
+  return did_map_logical_partitions;
+}
diff --git a/roots.h b/roots.h
index 46bb77e02..702af8de5 100644
--- a/roots.h
+++ b/roots.h
@@ -53,4 +53,6 @@ int format_volume(const char* volume, const char* directory);
 // mounted (/tmp and /cache) are mounted.  Returns 0 on success.
 int setup_install_mounts();
 
+bool logical_partitions_mapped();
+
 #endif  // RECOVERY_ROOTS_H_