Expand virtio_block check to other virtual devicesHEADq10.0

The Android Emulator isn't the only virtual device the virtio-block
detection code is useful for, and those platforms might not set any
discriminating properties to indicate that they are virtual.

Rework the virtio-block major detection to use /proc/devices instead
of hardcoding the assumption that any virtual platform can have
virtio-block at any experimental major; the new code permits only the
exact experimental major assigned to virtio-block.

The new code runs everywhere, but it will only run once and could be
expanded later to detect dynamic or experimental majors.

Bug: 156286088
Change-Id: Ieae805d08fddd0124a397636f04d99194a9ef7e5
Merged-In: Ieae805d08fddd0124a397636f04d99194a9ef7e5
(cherry picked from commit d3c230b5c9ba6e242c0a6b290a185517f2c118e8)

1 files changed, 4 insertions, 7 deletions

diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index 2435819..7573877 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -79,6 +79,7 @@ using android::vold::BindMount;
 using android::vold::CreateDir;
 using android::vold::DeleteDirContents;
 using android::vold::DeleteDirContentsAndDir;
+using android::vold::IsVirtioBlkDevice;
 using android::vold::Symlink;
 using android::vold::Unlink;
 using android::vold::UnmountTree;
@@ -95,8 +96,6 @@ static const std::string kEmptyString("");
 static const unsigned int kSizeVirtualDisk = 536870912;
 
 static const unsigned int kMajorBlockMmc = 179;
-static const unsigned int kMajorBlockExperimentalMin = 240;
-static const unsigned int kMajorBlockExperimentalMax = 254;
 
 VolumeManager* VolumeManager::sInstance = NULL;
 
@@ -215,12 +214,10 @@ void VolumeManager::handleBlockEvent(NetlinkEvent* evt) {
             for (const auto& source : mDiskSources) {
                 if (source->matches(eventPath)) {
                     // For now, assume that MMC and virtio-blk (the latter is
-                    // emulator-specific; see Disk.cpp for details) devices are SD,
-                    // and that everything else is USB
+                    // specific to virtual platforms; see Utils.cpp for details)
+                    // devices are SD, and that everything else is USB
                     int flags = source->getFlags();
-                    if (major == kMajorBlockMmc || (android::vold::IsRunningInEmulator() &&
-                                                    major >= (int)kMajorBlockExperimentalMin &&
-                                                    major <= (int)kMajorBlockExperimentalMax)) {
+                    if (major == kMajorBlockMmc || IsVirtioBlkDevice(major)) {
                         flags |= android::vold::Disk::Flags::kSd;
                     } else if (eventPath.find("ufs") != std::string::npos) {
                         flags |= android::vold::Disk::Flags::kSd;