commit eef49c9e3ca7ad84cfc1b651dada590528797b0d
author Palmer Dabbelt <palmerdabbelt@google.com> Fri Oct 02 18:13:29 2020 -0700
committer Akilesh Kailash <akailash@google.com> Fri Oct 16 18:16:55 2020 +0000
tree 356f4933ae65e2c1d8d7c49835feac1333f55253
parent 219b3487f89a630bb4065c31c3a21e8528322346

libdm: dm-user target creation takes an additional argument

Rather than using some implicit naming scheme, we've decided to just let
userspace pick whatever control device naming scheme it wants.  This requires
an additional argument to be passed to the kernel.

Test: cow_snapuserd_test
Bug: 168259959
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Change-Id: Ibf7f378b67abb6ca7457a9fdc9b8739e3d31bee3
Signed-off-by: Akilesh Kailash <akailash@google.com>

fs_mgr/libdm/dm_target.cpp

diff --git a/fs_mgr/libdm/dm_target.cpp b/fs_mgr/libdm/dm_target.cpp
index 8788b5a..ef46eb9 100644
--- a/fs_mgr/libdm/dm_target.cpp
+++ b/fs_mgr/libdm/dm_target.cpp
@@ -284,6 +284,7 @@
     std::vector<std::string> argv;
     argv.push_back(std::to_string(start()));
     argv.push_back(std::to_string(size()));
+    argv.push_back(control_device());
     return android::base::Join(argv, " ");
 }
 

fs_mgr/libdm/include/libdm/dm_target.h

diff --git a/fs_mgr/libdm/include/libdm/dm_target.h b/fs_mgr/libdm/include/libdm/dm_target.h
index 57e3884..478a3c6 100644
--- a/fs_mgr/libdm/include/libdm/dm_target.h
+++ b/fs_mgr/libdm/include/libdm/dm_target.h
@@ -311,10 +311,15 @@
 
 class DmTargetUser final : public DmTarget {
   public:
-    DmTargetUser(uint64_t start, uint64_t length) : DmTarget(start, length) {}
+    DmTargetUser(uint64_t start, uint64_t length, std::string control_device)
+        : DmTarget(start, length), control_device_(control_device) {}
 
     std::string name() const override { return "user"; }
+    std::string control_device() const { return control_device_; }
     std::string GetParameterString() const override;
+
+  private:
+    std::string control_device_;
 };
 
 }  // namespace dm

fs_mgr/tools/dmctl.cpp

diff --git a/fs_mgr/tools/dmctl.cpp b/fs_mgr/tools/dmctl.cpp
index 9edcda7..62ca162 100644
--- a/fs_mgr/tools/dmctl.cpp
+++ b/fs_mgr/tools/dmctl.cpp
@@ -177,7 +177,12 @@
             return std::make_unique<DmTargetSnapshot>(start_sector, num_sectors, base_device,
                                                       cow_device, mode, chunk_size);
         } else if (target_type == "user") {
-            return std::make_unique<DmTargetUser>(start_sector, num_sectors);
+            if (!HasArgs(1)) {
+                std::cerr << "Expected \"user\" <control_device_name>" << std::endl;
+                return nullptr;
+            }
+            std::string control_device = NextArg();
+            return std::make_unique<DmTargetUser>(start_sector, num_sectors, control_device);
         } else {
             std::cerr << "Unrecognized target type: " << target_type << std::endl;
             return nullptr;