libfiemap: Add a MapAllImages() helper.

This adds a helper for first-stage init to easily map partitions backed
by /data. This can be used for the scratch partition as well as DSU
partitions.

Bug: 134949511
Test: fiemap_image_test
Change-Id: I46246b41ce19442d1476b9959e34df0e1bff58c3

fs_mgr/libfiemap/binder.cpp

@@ -46,6 +46,7 @@ class ImageManagerBinder final : public IImageManager {
     bool DisableImage(const std::string& name) override;
     bool RemoveDisabledImages() override;
     bool GetMappedImageDevice(const std::string& name, std::string* device) override;
+    bool MapAllImages(const std::function<bool(std::set<std::string>)>& init) override;
 
     std::vector<std::string> GetAllBackingImages() override;
 
@@ -191,6 +192,11 @@ bool ImageManagerBinder::GetMappedImageDevice(const std::string& name, std::stri
     return !device->empty();
 }
 
+bool ImageManagerBinder::MapAllImages(const std::function<bool(std::set<std::string>)>&) {
+    LOG(ERROR) << __PRETTY_FUNCTION__ << " not available over binder";
+    return false;
+}
+
 static android::sp<IGsid> AcquireIGsid(const std::chrono::milliseconds& timeout_ms) {
     if (android::base::GetProperty("init.svc.gsid", "") != "running") {
         if (!android::base::SetProperty("ctl.start", "gsid") ||

fs_mgr/libfiemap/image_manager.cpp

@@ -42,7 +42,10 @@ using android::dm::DmTargetLinear;
 using android::dm::LoopControl;
 using android::fs_mgr::CreateLogicalPartition;
 using android::fs_mgr::CreateLogicalPartitionParams;
+using android::fs_mgr::CreateLogicalPartitions;
 using android::fs_mgr::DestroyLogicalPartition;
+using android::fs_mgr::GetBlockDevicePartitionName;
+using android::fs_mgr::GetBlockDevicePartitionNames;
 using android::fs_mgr::GetPartitionName;
 
 static constexpr char kTestImageMetadataDir[] = "/metadata/gsi/test";
@@ -669,6 +672,29 @@ bool ImageManager::GetMappedImageDevice(const std::string& name, std::string* de
     return dm.GetDmDevicePathByName(name, device);
 }
 
+bool ImageManager::MapAllImages(const std::function<bool(std::set<std::string>)>& init) {
+    if (!MetadataExists(metadata_dir_)) {
+        return true;
+    }
+
+    auto metadata = OpenMetadata(metadata_dir_);
+    if (!metadata) {
+        return false;
+    }
+
+    std::set<std::string> devices;
+    for (const auto& name : GetBlockDevicePartitionNames(*metadata.get())) {
+        devices.emplace(name);
+    }
+    if (!init(std::move(devices))) {
+        return false;
+    }
+
+    auto data_device = GetMetadataSuperBlockDevice(*metadata.get());
+    auto data_partition_name = GetBlockDevicePartitionName(*data_device);
+    return CreateLogicalPartitions(*metadata.get(), data_partition_name);
+}
+
 std::unique_ptr<MappedDevice> MappedDevice::Open(IImageManager* manager,
                                                  const std::chrono::milliseconds& timeout_ms,
                                                  const std::string& name) {

fs_mgr/libfiemap/image_test.cpp

@@ -239,9 +239,19 @@ TEST_F(ImageTest, IndirectMount) {
 
     ASSERT_TRUE(submanager_->CreateBackingImage(test_image_name_, kTestImageSize, false, nullptr));
 
+    std::set<std::string> backing_devices;
+    auto init = [&](std::set<std::string> devices) -> bool {
+        backing_devices = std::move(devices);
+        return true;
+    };
+
     std::string path;
     ASSERT_TRUE(submanager_->MapImageDevice(test_image_name_, 5s, &path));
     ASSERT_TRUE(android::base::StartsWith(path, "/dev/block/dm-"));
+    ASSERT_TRUE(submanager_->UnmapImageDevice(test_image_name_));
+    ASSERT_TRUE(submanager_->MapAllImages(init));
+    ASSERT_FALSE(backing_devices.empty());
+    ASSERT_TRUE(submanager_->UnmapImageDevice(test_image_name_));
 }
 
 bool Mkdir(const std::string& path) {

fs_mgr/libfiemap/include/libfiemap/image_manager.h

@@ -21,6 +21,7 @@
 #include <chrono>
 #include <functional>
 #include <memory>
+#include <set>
 #include <string>
 
 #include <android-base/unique_fd.h>
@@ -89,6 +90,14 @@ class IImageManager {
     // not necessary.
     virtual bool GetMappedImageDevice(const std::string& name, std::string* device) = 0;
 
+    // Map all images owned by this manager. This is only intended to be used
+    // during first-stage init, and as such, it does not provide a timeout
+    // (meaning libdm races can't be resolved, as ueventd is not available),
+    // and is not available over binder.
+    //
+    // The callback provided is given the list of dependent block devices.
+    virtual bool MapAllImages(const std::function<bool(std::set<std::string>)>& init) = 0;
+
     // Mark an image as disabled. This is useful for marking an image as
     // will-be-deleted in recovery, since recovery cannot mount /data.
     //
@@ -137,6 +146,7 @@ class ImageManager final : public IImageManager {
     bool DisableImage(const std::string& name) override;
     bool RemoveDisabledImages() override;
     bool GetMappedImageDevice(const std::string& name, std::string* device) override;
+    bool MapAllImages(const std::function<bool(std::set<std::string>)>& init) override;
 
     std::vector<std::string> GetAllBackingImages();
     // Same as CreateBackingImage, but provides a progress notification.