Merge "libdm: add an api to unwind dm stack"
diff --git a/fs_mgr/libdm/dm.cpp b/fs_mgr/libdm/dm.cpp
index 824ee43..809318c 100644
--- a/fs_mgr/libdm/dm.cpp
+++ b/fs_mgr/libdm/dm.cpp
@@ -16,12 +16,14 @@
#include "libdm/dm.h"
+#include <linux/dm-ioctl.h>
#include <sys/ioctl.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <chrono>
#include <functional>
+#include <string_view>
#include <thread>
#include <android-base/file.h>
@@ -504,5 +506,74 @@
return std::string{spec.target_type, sizeof(spec.target_type)};
}
+static bool ExtractBlockDeviceName(const std::string& path, std::string* name) {
+ static constexpr std::string_view kDevBlockPrefix("/dev/block/");
+ if (android::base::StartsWith(path, kDevBlockPrefix)) {
+ *name = path.substr(kDevBlockPrefix.length());
+ return true;
+ }
+ return false;
+}
+
+bool DeviceMapper::IsDmBlockDevice(const std::string& path) {
+ std::string name;
+ if (!ExtractBlockDeviceName(path, &name)) {
+ return false;
+ }
+ return android::base::StartsWith(name, "dm-");
+}
+
+std::optional<std::string> DeviceMapper::GetDmDeviceNameByPath(const std::string& path) {
+ std::string name;
+ if (!ExtractBlockDeviceName(path, &name)) {
+ LOG(WARNING) << path << " is not a block device";
+ return std::nullopt;
+ }
+ if (!android::base::StartsWith(name, "dm-")) {
+ LOG(WARNING) << path << " is not a dm device";
+ return std::nullopt;
+ }
+ std::string dm_name_file = "/sys/block/" + name + "/dm/name";
+ std::string dm_name;
+ if (!android::base::ReadFileToString(dm_name_file, &dm_name)) {
+ PLOG(ERROR) << "Failed to read file " << dm_name_file;
+ return std::nullopt;
+ }
+ dm_name = android::base::Trim(dm_name);
+ return dm_name;
+}
+
+std::optional<std::string> DeviceMapper::GetParentBlockDeviceByPath(const std::string& path) {
+ std::string name;
+ if (!ExtractBlockDeviceName(path, &name)) {
+ LOG(WARNING) << path << " is not a block device";
+ return std::nullopt;
+ }
+ if (!android::base::StartsWith(name, "dm-")) {
+ // Reached bottom of the device mapper stack.
+ return std::nullopt;
+ }
+ auto slaves_dir = "/sys/block/" + name + "/slaves";
+ auto dir = std::unique_ptr<DIR, decltype(&closedir)>(opendir(slaves_dir.c_str()), closedir);
+ if (dir == nullptr) {
+ PLOG(ERROR) << "Failed to open: " << slaves_dir;
+ return std::nullopt;
+ }
+ std::string sub_device_name = "";
+ for (auto entry = readdir(dir.get()); entry; entry = readdir(dir.get())) {
+ if (entry->d_type != DT_LNK) continue;
+ if (!sub_device_name.empty()) {
+ LOG(ERROR) << "Too many slaves in " << slaves_dir;
+ return std::nullopt;
+ }
+ sub_device_name = entry->d_name;
+ }
+ if (sub_device_name.empty()) {
+ LOG(ERROR) << "No slaves in " << slaves_dir;
+ return std::nullopt;
+ }
+ return "/dev/block/" + sub_device_name;
+}
+
} // namespace dm
} // namespace android
diff --git a/fs_mgr/libdm/dm_test.cpp b/fs_mgr/libdm/dm_test.cpp
index 1695953..b7f31bc 100644
--- a/fs_mgr/libdm/dm_test.cpp
+++ b/fs_mgr/libdm/dm_test.cpp
@@ -29,6 +29,7 @@
#include <thread>
#include <android-base/file.h>
+#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <gtest/gtest.h>
#include <libdm/dm.h>
@@ -544,3 +545,63 @@
ASSERT_NE(0, access(path.c_str(), F_OK));
ASSERT_EQ(ENOENT, errno);
}
+
+TEST(libdm, IsDmBlockDevice) {
+ unique_fd tmp(CreateTempFile("file_1", 4096));
+ ASSERT_GE(tmp, 0);
+ LoopDevice loop(tmp, 10s);
+ ASSERT_TRUE(loop.valid());
+ ASSERT_TRUE(android::base::StartsWith(loop.device(), "/dev/block"));
+
+ DmTable table;
+ ASSERT_TRUE(table.Emplace<DmTargetLinear>(0, 1, loop.device(), 0));
+ ASSERT_TRUE(table.valid());
+
+ TempDevice dev("libdm-test-dm-linear", table);
+ ASSERT_TRUE(dev.valid());
+
+ DeviceMapper& dm = DeviceMapper::Instance();
+ ASSERT_TRUE(dm.IsDmBlockDevice(dev.path()));
+ ASSERT_FALSE(dm.IsDmBlockDevice(loop.device()));
+}
+
+TEST(libdm, GetDmDeviceNameByPath) {
+ unique_fd tmp(CreateTempFile("file_1", 4096));
+ ASSERT_GE(tmp, 0);
+ LoopDevice loop(tmp, 10s);
+ ASSERT_TRUE(loop.valid());
+ ASSERT_TRUE(android::base::StartsWith(loop.device(), "/dev/block"));
+
+ DmTable table;
+ ASSERT_TRUE(table.Emplace<DmTargetLinear>(0, 1, loop.device(), 0));
+ ASSERT_TRUE(table.valid());
+
+ TempDevice dev("libdm-test-dm-linear", table);
+ ASSERT_TRUE(dev.valid());
+
+ DeviceMapper& dm = DeviceMapper::Instance();
+ // Not a dm device, GetDmDeviceNameByPath will return std::nullopt.
+ ASSERT_FALSE(dm.GetDmDeviceNameByPath(loop.device()));
+ auto name = dm.GetDmDeviceNameByPath(dev.path());
+ ASSERT_EQ("libdm-test-dm-linear", *name);
+}
+
+TEST(libdm, GetParentBlockDeviceByPath) {
+ unique_fd tmp(CreateTempFile("file_1", 4096));
+ ASSERT_GE(tmp, 0);
+ LoopDevice loop(tmp, 10s);
+ ASSERT_TRUE(loop.valid());
+ ASSERT_TRUE(android::base::StartsWith(loop.device(), "/dev/block"));
+
+ DmTable table;
+ ASSERT_TRUE(table.Emplace<DmTargetLinear>(0, 1, loop.device(), 0));
+ ASSERT_TRUE(table.valid());
+
+ TempDevice dev("libdm-test-dm-linear", table);
+ ASSERT_TRUE(dev.valid());
+
+ DeviceMapper& dm = DeviceMapper::Instance();
+ ASSERT_FALSE(dm.GetParentBlockDeviceByPath(loop.device()));
+ auto sub_block_device = dm.GetParentBlockDeviceByPath(dev.path());
+ ASSERT_EQ(loop.device(), *sub_block_device);
+}
diff --git a/fs_mgr/libdm/include/libdm/dm.h b/fs_mgr/libdm/include/libdm/dm.h
index 830c5e8..418210c 100644
--- a/fs_mgr/libdm/include/libdm/dm.h
+++ b/fs_mgr/libdm/include/libdm/dm.h
@@ -214,6 +214,19 @@
static std::string GetTargetType(const struct dm_target_spec& spec);
+ // Returns true if given path is a path to a dm block device.
+ bool IsDmBlockDevice(const std::string& path);
+
+ // Returns name of a dm-device with the given path, or std::nulloptr if given path is not a
+ // dm-device.
+ std::optional<std::string> GetDmDeviceNameByPath(const std::string& path);
+
+ // Returns a parent block device of a dm device with the given path, or std::nullopt if:
+ // * Given path doesn't correspond to a dm device.
+ // * A dm device is based on top of more than one block devices.
+ // * A failure occurred.
+ std::optional<std::string> GetParentBlockDeviceByPath(const std::string& path);
+
private:
// Maximum possible device mapper targets registered in the kernel.
// This is only used to read the list of targets from kernel so we allocate