fs_mgr: Allow using major:minor device strings in CreateLogicalPartition.
IPartitionOpener is useful for writing gtests, however, it can't easily
be used with CreateLogicalPartition. fs_mgr assumes the super partition
name will map to /dev/block/by-name/super whereas in tests we want to
redirect it to a different block device.
This CL makes two changes. First, it adds a new method to IPartitionOpener
to return a "device string" for a device name. The string must either be
an absolute path (for example /dev/block/by-name/super) or a major:minor
sequence, since device-mapper will accept either.
Second, CreateLogicalPartition now accepts an optional IPartitionOpener.
When converting block devices to paths, it uses the opener instead of
automatically prepending /dev/block/by-name.
Bug: 139204329
Test: liblp_test gtest
libsnapshot_test gtest
Change-Id: Id6b3120cc2ef5c0dd941b29ff96215ad3c8ec848
diff --git a/fs_mgr/fs_mgr_dm_linear.cpp b/fs_mgr/fs_mgr_dm_linear.cpp
index eaa515a..1b85b47 100644
--- a/fs_mgr/fs_mgr_dm_linear.cpp
+++ b/fs_mgr/fs_mgr_dm_linear.cpp
@@ -52,29 +52,36 @@
using DmTargetZero = android::dm::DmTargetZero;
using DmTargetLinear = android::dm::DmTargetLinear;
-static bool GetPhysicalPartitionDevicePath(const LpMetadata& metadata,
+static bool GetPhysicalPartitionDevicePath(const IPartitionOpener& opener,
+ const LpMetadata& metadata,
const LpMetadataBlockDevice& block_device,
- const std::string& super_device,
- std::string* result) {
- // Note: device-mapper will not accept symlinks, so we must use realpath
- // here.
- std::string name = GetBlockDevicePartitionName(block_device);
- std::string path = "/dev/block/by-name/" + name;
+ const std::string& super_device, std::string* result) {
// If the super device is the source of this block device's metadata,
// make sure we use the correct super device (and not just "super",
// which might not exist.)
+ std::string name = GetBlockDevicePartitionName(block_device);
+ std::string dev_string = opener.GetDeviceString(name);
if (GetMetadataSuperBlockDevice(metadata) == &block_device) {
- path = super_device;
+ dev_string = opener.GetDeviceString(super_device);
}
- if (!android::base::Realpath(path, result)) {
- PERROR << "realpath: " << path;
- return false;
+
+ // Note: device-mapper will not accept symlinks, so we must use realpath
+ // here. If the device string is a major:minor sequence, we don't need to
+ // to call Realpath (it would not work anyway).
+ if (android::base::StartsWith(dev_string, "/")) {
+ if (!android::base::Realpath(dev_string, result)) {
+ PERROR << "realpath: " << dev_string;
+ return false;
+ }
+ } else {
+ *result = dev_string;
}
return true;
}
-static bool CreateDmTable(const LpMetadata& metadata, const LpMetadataPartition& partition,
- const std::string& super_device, DmTable* table) {
+static bool CreateDmTable(const IPartitionOpener& opener, const LpMetadata& metadata,
+ const LpMetadataPartition& partition, const std::string& super_device,
+ DmTable* table) {
uint64_t sector = 0;
for (size_t i = 0; i < partition.num_extents; i++) {
const auto& extent = metadata.extents[partition.first_extent_index + i];
@@ -85,12 +92,13 @@
break;
case LP_TARGET_TYPE_LINEAR: {
const auto& block_device = metadata.block_devices[extent.target_source];
- std::string path;
- if (!GetPhysicalPartitionDevicePath(metadata, block_device, super_device, &path)) {
+ std::string dev_string;
+ if (!GetPhysicalPartitionDevicePath(opener, metadata, block_device, super_device,
+ &dev_string)) {
LOG(ERROR) << "Unable to complete device-mapper table, unknown block device";
return false;
}
- target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, path,
+ target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, dev_string,
extent.target_data);
break;
}
@@ -179,8 +187,12 @@
}
}
+ PartitionOpener default_opener;
+ const IPartitionOpener* opener =
+ params.partition_opener ? params.partition_opener : &default_opener;
+
DmTable table;
- if (!CreateDmTable(*metadata, *partition, params.block_device, &table)) {
+ if (!CreateDmTable(*opener, *metadata, *partition, params.block_device, &table)) {
return false;
}
if (params.force_writable) {
diff --git a/fs_mgr/include/fs_mgr_dm_linear.h b/fs_mgr/include/fs_mgr_dm_linear.h
index 6eb541c..8e2fdbb 100644
--- a/fs_mgr/include/fs_mgr_dm_linear.h
+++ b/fs_mgr/include/fs_mgr_dm_linear.h
@@ -73,6 +73,10 @@
// If this is non-empty, it will override the device mapper name (by
// default the partition name will be used).
std::string device_name;
+
+ // If non-null, this will use the specified IPartitionOpener rather than
+ // the default one.
+ const IPartitionOpener* partition_opener = nullptr;
};
bool CreateLogicalPartition(const CreateLogicalPartitionParams& params, std::string* path);
diff --git a/fs_mgr/liblp/include/liblp/partition_opener.h b/fs_mgr/liblp/include/liblp/partition_opener.h
index e506bd5..7c9100b 100644
--- a/fs_mgr/liblp/include/liblp/partition_opener.h
+++ b/fs_mgr/liblp/include/liblp/partition_opener.h
@@ -62,6 +62,11 @@
// Return block device information about the given named physical partition.
// The name can be an absolute path if the full path is already known.
virtual bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const = 0;
+
+ // Return a path that can be used to pass the block device to device-mapper.
+ // This must either result in an absolute path, or a major:minor device
+ // sequence.
+ virtual std::string GetDeviceString(const std::string& partition_name) const = 0;
};
// Helper class to implement IPartitionOpener. If |partition_name| is not an
@@ -71,6 +76,7 @@
virtual android::base::unique_fd Open(const std::string& partition_name,
int flags) const override;
virtual bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const override;
+ virtual std::string GetDeviceString(const std::string& partition_name) const override;
};
} // namespace fs_mgr
diff --git a/fs_mgr/liblp/partition_opener.cpp b/fs_mgr/liblp/partition_opener.cpp
index cc4a882..f1e8fc2 100644
--- a/fs_mgr/liblp/partition_opener.cpp
+++ b/fs_mgr/liblp/partition_opener.cpp
@@ -100,5 +100,9 @@
return GetBlockDeviceInfo(path, info);
}
+std::string PartitionOpener::GetDeviceString(const std::string& partition_name) const {
+ return GetPartitionAbsolutePath(partition_name);
+}
+
} // namespace fs_mgr
} // namespace android
