libfiemap_writer: Allow callers to query the block device of a file.
Bug: 126249541
Test: manual test
Change-Id: I478bcf60caf0cedc84189c39fee4b6c4f94b6ed6
diff --git a/fs_mgr/libfiemap_writer/fiemap_writer.cpp b/fs_mgr/libfiemap_writer/fiemap_writer.cpp
index b9b75f8..fc24a17 100644
--- a/fs_mgr/libfiemap_writer/fiemap_writer.cpp
+++ b/fs_mgr/libfiemap_writer/fiemap_writer.cpp
@@ -126,7 +126,8 @@
return DeviceMapperStackPop(bdev_next, bdev_raw);
}
-static bool FileToBlockDevicePath(const std::string& file_path, std::string* bdev_path) {
+bool FiemapWriter::GetBlockDeviceForFile(const std::string& file_path, std::string* bdev_path,
+ bool* uses_dm) {
struct stat sb;
if (stat(file_path.c_str(), &sb)) {
PLOG(ERROR) << "Failed to get stat for: " << file_path;
@@ -146,6 +147,10 @@
return false;
}
+ if (uses_dm) {
+ *uses_dm = (bdev_raw != bdev);
+ }
+
LOG(DEBUG) << "Popped device (" << bdev_raw << ") from device mapper stack starting with ("
<< bdev << ")";
@@ -458,7 +463,7 @@
}
std::string bdev_path;
- if (!FileToBlockDevicePath(abs_path, &bdev_path)) {
+ if (!GetBlockDeviceForFile(abs_path, &bdev_path)) {
LOG(ERROR) << "Failed to get block dev path for file: " << file_path;
cleanup(abs_path, create);
return nullptr;
diff --git a/fs_mgr/libfiemap_writer/include/libfiemap_writer/fiemap_writer.h b/fs_mgr/libfiemap_writer/include/libfiemap_writer/fiemap_writer.h
index edbae77..b5472c9 100644
--- a/fs_mgr/libfiemap_writer/include/libfiemap_writer/fiemap_writer.h
+++ b/fs_mgr/libfiemap_writer/include/libfiemap_writer/fiemap_writer.h
@@ -57,6 +57,13 @@
// FiemapWriter::Open).
static bool HasPinnedExtents(const std::string& file_path);
+ // Returns the underlying block device of a file. This will look past device-mapper layers.
+ // If an intermediate device-mapper layer would not maintain a 1:1 mapping (i.e. is a non-
+ // trivial dm-linear), then this will fail. If device-mapper nodes are encountered, then
+ // |uses_dm| will be set to true.
+ static bool GetBlockDeviceForFile(const std::string& file_path, std::string* bdev_path,
+ bool* uses_dm = nullptr);
+
// The counter part of Write(). It is an error for the offset to be unaligned with
// the block device's block size.
// In case of error, the contents of buffer MUST be discarded.