Merge "fs_mgr: Allow using major:minor device strings in CreateLogicalPartition."

4 files changed, 43 insertions, 17 deletions

diff --git a/fs_mgr/fs_mgr_dm_linear.cpp b/fs_mgr/fs_mgr_dm_linear.cpp
index eaa515aea..1b85b475a 100644
--- a/fs_mgr/fs_mgr_dm_linear.cpp
+++ b/fs_mgr/fs_mgr_dm_linear.cpp
@@ -52,29 +52,36 @@ using DmTarget = android::dm::DmTarget;
 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 @@ static bool CreateDmTable(const LpMetadata& metadata, const LpMetadataPartition&
                 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 @@ bool CreateLogicalPartition(const CreateLogicalPartitionParams& params, std::str
         }
     }
 
+    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 6eb541ced..8e2fdbb19 100644
--- a/fs_mgr/include/fs_mgr_dm_linear.h
+++ b/fs_mgr/include/fs_mgr_dm_linear.h
@@ -73,6 +73,10 @@ struct CreateLogicalPartitionParams {
     // 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 e506bd5c2..7c9100b55 100644
--- a/fs_mgr/liblp/include/liblp/partition_opener.h
+++ b/fs_mgr/liblp/include/liblp/partition_opener.h
@@ -62,6 +62,11 @@ class IPartitionOpener {
     // 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 @@ class PartitionOpener : public IPartitionOpener {
     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 cc4a8821f..f1e8fc20c 100644
--- a/fs_mgr/liblp/partition_opener.cpp
+++ b/fs_mgr/liblp/partition_opener.cpp
@@ -100,5 +100,9 @@ bool PartitionOpener::GetInfo(const std::string& partition_name, BlockDeviceInfo
     return GetBlockDeviceInfo(path, info);
 }
 
+std::string PartitionOpener::GetDeviceString(const std::string& partition_name) const {
+    return GetPartitionAbsolutePath(partition_name);
+}
+
 }  // namespace fs_mgr
 }  // namespace android