Merge "adds LO_FLAGS_AUTOCLEAR for loop device of zram backing device"

fs_mgr/fs_mgr.cpp

@@ -2119,6 +2119,9 @@ static bool PrepareZramBackingDevice(off64_t size) {
         PERROR << "Cannot open " << loop_device;
         return false;
     }
+    if (!LoopControl::SetAutoClearStatus(loop_fd.get())) {
+        PERROR << "Failed set LO_FLAGS_AUTOCLEAR for " << loop_device;
+    }
     if (!LoopControl::EnableDirectIo(loop_fd.get())) {
         return false;
     }

fs_mgr/libdm/include/libdm/loop_control.h

@@ -46,6 +46,9 @@ class LoopControl final {
     // Enable Direct I/O on a loop device. This requires kernel 4.9+.
     static bool EnableDirectIo(int fd);
 
+    // Set LO_FLAGS_AUTOCLEAR on a loop device.
+    static bool SetAutoClearStatus(int fd);
+
     LoopControl(const LoopControl&) = delete;
     LoopControl& operator=(const LoopControl&) = delete;
     LoopControl& operator=(LoopControl&&) = default;

fs_mgr/libdm/loop_control.cpp

@@ -133,6 +133,16 @@ bool LoopControl::EnableDirectIo(int fd) {
     return true;
 }
 
+bool LoopControl::SetAutoClearStatus(int fd) {
+    struct loop_info64 info = {};
+
+    info.lo_flags |= LO_FLAGS_AUTOCLEAR;
+    if (ioctl(fd, LOOP_SET_STATUS64, &info)) {
+        return false;
+    }
+    return true;
+}
+
 LoopDevice::LoopDevice(android::base::borrowed_fd fd, const std::chrono::milliseconds& timeout_ms,
                        bool auto_close)
     : fd_(fd), owned_fd_(-1) {