Merge changes from topic "ext4 checkpointing"

* changes:
  make checkpointing work on ext4
  Adding bow dm-target

fs_mgr/fs_mgr.cpp

@@ -850,7 +850,7 @@ bool fs_mgr_update_logical_partition(struct fstab_rec* rec) {
 }
 
 bool fs_mgr_update_checkpoint_partition(struct fstab_rec* rec) {
-    if (fs_mgr_is_checkpoint(rec)) {
+    if (fs_mgr_is_checkpoint_fs(rec)) {
         if (!strcmp(rec->fs_type, "f2fs")) {
             std::string opts(rec->fs_options);
 
@@ -860,9 +860,42 @@ bool fs_mgr_update_checkpoint_partition(struct fstab_rec* rec) {
         } else {
             LERROR << rec->fs_type << " does not implement checkpoints.";
         }
-    } else if (rec->fs_mgr_flags & MF_CHECKPOINT_BLK) {
-        LERROR << "Block based checkpoint not implemented.";
-        return false;
+    } else if (fs_mgr_is_checkpoint_blk(rec)) {
+        call_vdc({"checkpoint", "restoreCheckpoint", rec->blk_device});
+
+        android::base::unique_fd fd(
+                TEMP_FAILURE_RETRY(open(rec->blk_device, O_RDONLY | O_CLOEXEC)));
+        if (!fd) {
+            PERROR << "Cannot open device " << rec->blk_device;
+            return false;
+        }
+
+        uint64_t size = get_block_device_size(fd) / 512;
+        if (!size) {
+            PERROR << "Cannot get device size";
+            return false;
+        }
+
+        android::dm::DmTable table;
+        if (!table.AddTarget(
+                    std::make_unique<android::dm::DmTargetBow>(0, size, rec->blk_device))) {
+            LERROR << "Failed to add Bow target";
+            return false;
+        }
+
+        DeviceMapper& dm = DeviceMapper::Instance();
+        if (!dm.CreateDevice("bow", table)) {
+            PERROR << "Failed to create bow device";
+            return false;
+        }
+
+        std::string name;
+        if (!dm.GetDmDevicePathByName("bow", &name)) {
+            PERROR << "Failed to get bow device name";
+            return false;
+        }
+
+        rec->blk_device = strdup(name.c_str());
     }
     return true;
 }

fs_mgr/libdm/include/libdm/dm_target.h

@@ -156,6 +156,20 @@ class DmTargetVerityString final : public DmTarget {
     std::string target_string_;
 };
 
+// dm-bow is the backup on write target that can provide checkpoint capability
+// for file systems that do not support checkpoints natively
+class DmTargetBow final : public DmTarget {
+  public:
+    DmTargetBow(uint64_t start, uint64_t length, const std::string& target_string)
+        : DmTarget(start, length), target_string_(target_string) {}
+
+    std::string name() const override { return "bow"; }
+    std::string GetParameterString() const override { return target_string_; }
+
+  private:
+    std::string target_string_;
+};
+
 }  // namespace dm
 }  // namespace android
 

fs_mgr/tools/dmctl.cpp

@@ -42,6 +42,7 @@ using DmTarget = ::android::dm::DmTarget;
 using DmTargetLinear = ::android::dm::DmTargetLinear;
 using DmTargetZero = ::android::dm::DmTargetZero;
 using DmTargetAndroidVerity = ::android::dm::DmTargetAndroidVerity;
+using DmTargetBow = ::android::dm::DmTargetBow;
 using DmTargetTypeInfo = ::android::dm::DmTargetTypeInfo;
 using DmBlockDevice = ::android::dm::DeviceMapper::DmBlockDevice;
 
@@ -108,6 +109,13 @@ class TargetParser final {
             std::string block_device = NextArg();
             return std::make_unique<DmTargetAndroidVerity>(start_sector, num_sectors, keyid,
                                                            block_device);
+        } else if (target_type == "bow") {
+            if (!HasArgs(1)) {
+                std::cerr << "Expected \"bow\" <block_device>" << std::endl;
+                return nullptr;
+            }
+            std::string block_device = NextArg();
+            return std::make_unique<DmTargetBow>(start_sector, num_sectors, block_device);
         } else {
             std::cerr << "Unrecognized target type: " << target_type << std::endl;
             return nullptr;

rootdir/init.rc

@@ -400,6 +400,7 @@ on post-fs-data
 
     # Make sure we have the device encryption key.
     start vold
+    exec - system system -- /system/bin/vdc checkpoint prepareDriveForCheckpoint /data
     installkey /data
 
     # Start bootcharting as soon as possible after the data partition is