Allow mapping of raw block devices to partition names
Allow mapping of raw block devices (those without a partition table)
to partition names for first stage mount and ueventd. For example, a
block device `vdb` that contains only an ext4 metadata partition could
be mapped to `metadata` such that /dev/block/by-name/metadata is
created.
The mapping is provided by the `androidboot.partition_map` bootconfig
or kernel command line parameter.
Bug: 159943320
Test: boot with raw vdb,metadata;vdc,userdata partitions
Change-Id: Ib6a939d6fb88b85c46c81d613425a127627a734b
diff --git a/init/block_dev_initializer.cpp b/init/block_dev_initializer.cpp
index 9c2a7bb..05e00ed 100644
--- a/init/block_dev_initializer.cpp
+++ b/init/block_dev_initializer.cpp
@@ -87,7 +87,13 @@
auto iter = devices->find(name);
if (iter == devices->end()) {
- return ListenerAction::kContinue;
+ auto partition_name = DeviceHandler::GetPartitionNameForDevice(uevent.device_name);
+ if (!partition_name.empty()) {
+ iter = devices->find(partition_name);
+ }
+ if (iter == devices->end()) {
+ return ListenerAction::kContinue;
+ }
}
LOG(VERBOSE) << __PRETTY_FUNCTION__ << ": found partition: " << name;
diff --git a/init/devices.cpp b/init/devices.cpp
index ce6298a..c510b23 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -46,6 +46,7 @@
using android::base::ReadFileToString;
using android::base::Readlink;
using android::base::Realpath;
+using android::base::Split;
using android::base::StartsWith;
using android::base::StringPrintf;
using android::base::Trim;
@@ -187,6 +188,36 @@
}
}
+std::string DeviceHandler::GetPartitionNameForDevice(const std::string& query_device) {
+ static const auto partition_map = [] {
+ std::vector<std::pair<std::string, std::string>> partition_map;
+ auto parser = [&partition_map](const std::string& key, const std::string& value) {
+ if (key != "androidboot.partition_map") {
+ return;
+ }
+ for (const auto& map : Split(value, ";")) {
+ auto map_pieces = Split(map, ",");
+ if (map_pieces.size() != 2) {
+ LOG(ERROR) << "Expected a comma separated device,partition mapping, but found '"
+ << map << "'";
+ continue;
+ }
+ partition_map.emplace_back(map_pieces[0], map_pieces[1]);
+ }
+ };
+ ImportKernelCmdline(parser);
+ ImportBootconfig(parser);
+ return partition_map;
+ }();
+
+ for (const auto& [device, partition] : partition_map) {
+ if (query_device == device) {
+ return partition;
+ }
+ }
+ return {};
+}
+
// Given a path that may start with a platform device, find the parent platform device by finding a
// parent directory with a 'subsystem' symlink that points to the platform bus.
// If it doesn't start with a platform device, return false
@@ -376,6 +407,10 @@
// If we don't have a partition name but we are a partition on a boot device, create a
// symlink of /dev/block/by-name/<device_name> for symmetry.
links.emplace_back("/dev/block/by-name/" + uevent.device_name);
+ auto partition_name = GetPartitionNameForDevice(uevent.device_name);
+ if (!partition_name.empty()) {
+ links.emplace_back("/dev/block/by-name/" + partition_name);
+ }
}
auto last_slash = uevent.path.rfind('/');
diff --git a/init/devices.h b/init/devices.h
index d70d746..f9f4d79 100644
--- a/init/devices.h
+++ b/init/devices.h
@@ -122,6 +122,12 @@
std::vector<std::string> GetBlockDeviceSymlinks(const Uevent& uevent) const;
+ // `androidboot.partition_map` allows associating a partition name for a raw block device
+ // through a comma separated and semicolon deliminated list. For example,
+ // `androidboot.partition_map=vdb,metadata;vdc,userdata` maps `vdb` to `metadata` and `vdc` to
+ // `userdata`.
+ static std::string GetPartitionNameForDevice(const std::string& device);
+
private:
bool FindPlatformDevice(std::string path, std::string* platform_device_path) const;
std::tuple<mode_t, uid_t, gid_t> GetDevicePermissions(