init: mount_handler: detect main block device more reliably

Current code is not portable beyond SCSI devices (e.g., UFS).
For example, eMMC and NVMe devices fail due to their extra postfix.

Change its logic to rewind each character until "queue" directory appears.

Test: Confirm md0p1, sda20, nvme0n1p3, mmcblk0p3 are all handled well.
Change-Id: I585ccf2d4a72f6ef8ecb203acdd72a1e32d3e749
Signed-off-by: Juhyung Park <qkrwngud825@gmail.com>

Author: arter97

init/mount_handler.cpp

@@ -73,19 +73,33 @@ void SetMountProperty(const MountHandlerEntry& entry, bool add) {
     std::string value;
     if (add) {
         value = entry.blk_device.substr(strlen(devblock));
-        if (android::base::StartsWith(value, "sd")) {
-            // All sd partitions inherit their queue characteristics
-            // from the whole device reference.  Strip partition number.
-            auto it = std::find_if(value.begin(), value.end(), [](char c) { return isdigit(c); });
-            if (it != value.end()) value.erase(it, value.end());
-        }
-        auto queue = "/sys/block/" + value + "/queue";
+
         struct stat sb;
-        if (stat(queue.c_str(), &sb) || !S_ISDIR(sb.st_mode)) value = "";
         if (stat(entry.mount_point.c_str(), &sb) || !S_ISDIR(sb.st_mode)) value = "";
         // Clear the noise associated with loopback and APEX.
         if (android::base::StartsWith(value, "loop")) value = "";
         if (android::base::StartsWith(entry.mount_point, "/apex/")) value = "";
+
+        if (!value.empty()) {
+            auto value_tmp = value;
+            std::string queue;
+            while (true) {
+                // Partitioned device don't have its own queue settings.
+                // Rewind each character until the main device appears.
+                queue = "/sys/block/" + value + "/queue";
+
+                if (!stat(queue.c_str(), &sb) && S_ISDIR(sb.st_mode)) {
+                    // Found device sysfs name
+                    break;
+                }
+
+                value.pop_back();
+                if (value.empty()) {
+                    LOG(ERROR) << "Failed to find block path for " << value_tmp;
+                    break;
+                }
+            }
+        }
     }
     auto mount_prop = entry.mount_point;
     if (mount_prop == "/") mount_prop = "/root";