commit 756d006746be0973aea701d539aff00280659278
author Alessio Balsini <balsini@google.com> Mon Jul 29 19:45:04 2019 +0100
committer Alessio Balsini <balsini@google.com> Mon Jul 29 20:35:56 2019 +0100
tree aa1e11f88df4870d26ab143af02fc403b991502d
parent 0e0c3b756b465dac694d72d5431b131b9c59c5e5

libdm: suspend and resume devices

In some cases it would be required to suspend the device to succesfully
complete some operations. An example is the suspension of the origin
device that is necessary to avoid data corruption when merging a
snapshot.

Introduce suspend and resume ioctls in libdm.

Bug: 137759376
Test: libdm_test
Change-Id: Id2ff34e930a8b32e570cb9f49da9cc3f65cb499c
Signed-off-by: Alessio Balsini <balsini@google.com>

fs_mgr/libdm/dm.cpp

diff --git a/fs_mgr/libdm/dm.cpp b/fs_mgr/libdm/dm.cpp
index 0ad8d9d..1d2683a 100644
--- a/fs_mgr/libdm/dm.cpp
+++ b/fs_mgr/libdm/dm.cpp
@@ -162,6 +162,24 @@
     return DmDeviceState::SUSPENDED;
 }
 
+bool DeviceMapper::ChangeState(const std::string& name, DmDeviceState state) {
+    if (state != DmDeviceState::SUSPENDED && state != DmDeviceState::ACTIVE) {
+        return false;
+    }
+
+    struct dm_ioctl io;
+    InitIo(&io, name);
+
+    if (state == DmDeviceState::SUSPENDED) io.flags = DM_SUSPEND_FLAG;
+
+    if (ioctl(fd_, DM_DEV_SUSPEND, &io) < 0) {
+        PLOG(ERROR) << "DM_DEV_SUSPEND "
+                    << (state == DmDeviceState::SUSPENDED ? "suspend" : "resume") << " failed";
+        return false;
+    }
+    return true;
+}
+
 bool DeviceMapper::CreateDevice(const std::string& name, const DmTable& table) {
     std::string ignore_path;
     if (!CreateDevice(name, table, &ignore_path, 0ms)) {

fs_mgr/libdm/dm_test.cpp

diff --git a/fs_mgr/libdm/dm_test.cpp b/fs_mgr/libdm/dm_test.cpp
index b28a8f2..da1c4a9 100644
--- a/fs_mgr/libdm/dm_test.cpp
+++ b/fs_mgr/libdm/dm_test.cpp
@@ -166,6 +166,34 @@
     ASSERT_TRUE(dev.Destroy());
 }
 
+TEST(libdm, DmSuspendResume) {
+    unique_fd tmp1(CreateTempFile("file_suspend_resume", 512));
+    ASSERT_GE(tmp1, 0);
+
+    LoopDevice loop_a(tmp1, 10s);
+    ASSERT_TRUE(loop_a.valid());
+
+    DmTable table;
+    ASSERT_TRUE(table.Emplace<DmTargetLinear>(0, 1, loop_a.device(), 0));
+    ASSERT_TRUE(table.valid());
+
+    TempDevice dev("libdm-test-dm-suspend-resume", table);
+    ASSERT_TRUE(dev.valid());
+    ASSERT_FALSE(dev.path().empty());
+
+    auto& dm = DeviceMapper::Instance();
+
+    // Test Set and Get status of device.
+    vector<DeviceMapper::TargetInfo> targets;
+    ASSERT_EQ(dm.GetState(dev.name()), DmDeviceState::ACTIVE);
+
+    ASSERT_TRUE(dm.ChangeState(dev.name(), DmDeviceState::SUSPENDED));
+    ASSERT_EQ(dm.GetState(dev.name()), DmDeviceState::SUSPENDED);
+
+    ASSERT_TRUE(dm.ChangeState(dev.name(), DmDeviceState::ACTIVE));
+    ASSERT_EQ(dm.GetState(dev.name()), DmDeviceState::ACTIVE);
+}
+
 TEST(libdm, DmVerityArgsAvb2) {
     std::string device = "/dev/block/platform/soc/1da4000.ufshc/by-name/vendor_a";
     std::string algorithm = "sha1";

fs_mgr/libdm/include/libdm/dm.h

diff --git a/fs_mgr/libdm/include/libdm/dm.h b/fs_mgr/libdm/include/libdm/dm.h
index 9c0c2f3..753b8c9 100644
--- a/fs_mgr/libdm/include/libdm/dm.h
+++ b/fs_mgr/libdm/include/libdm/dm.h
@@ -79,6 +79,11 @@
     // One of INVALID, SUSPENDED or ACTIVE.
     DmDeviceState GetState(const std::string& name) const;
 
+    // Puts the given device to the specified status, which must be either:
+    // - SUSPENDED: suspend the device, or
+    // - ACTIVE: resumes the device.
+    bool ChangeState(const std::string& name, DmDeviceState state);
+
     // Creates a device, loads the given table, and activates it. If the device
     // is not able to be activated, it is destroyed, and false is returned.
     // After creation, |path| contains the result of calling