Set block device as RO/RW before mount

umount is faster if an RO mount is on top of an RO block device.

Test: th
Bug: 349507086
Change-Id: I621cafd5b15c2c4e104ae7678a1bcf2588fe29b6
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index 5156754..ea2e3a8 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -826,6 +826,9 @@
     if (read_only) {
         mountflags |= MS_RDONLY;
     }
+    if (!fs_mgr_set_blk_ro(source, read_only)) {
+        PLOG(ERROR) << "Failed to set " << source << " as " << (read_only ? "RO" : "RW");
+    }
     int ret = 0;
     int save_errno = 0;
     int gc_allowance = 0;
@@ -880,9 +883,6 @@
     }
     PINFO << __FUNCTION__ << "(source=" << source << source_missing << ",target=" << target
           << target_missing << ",type=" << entry.fs_type << ")=" << ret;
-    if ((ret == 0) && (mountflags & MS_RDONLY) != 0) {
-        fs_mgr_set_blk_ro(source);
-    }
     if (ret == 0) {
         android::base::SetProperty("ro.boottime.init.mount." + Basename(target),
                                    std::to_string(t.duration().count()));