Merge "Change the remount command to be more container-friendly" am: d24c8484c8
am: 677288c80a
Change-Id: I96fdf4c334626649ca0e7437a0d9296758a9b062
diff --git a/adb/remount_service.cpp b/adb/remount_service.cpp
index 32ed28f..a4c7a5a 100644
--- a/adb/remount_service.cpp
+++ b/adb/remount_service.cpp
@@ -62,9 +62,9 @@
// The proc entry for / is full of lies, so check fstab instead.
// /proc/mounts lists rootfs and /dev/root, neither of which is what we want.
-static std::string find_mount(const char* dir) {
- if (strcmp(dir, "/") == 0) {
- return find_fstab_mount(dir);
+static std::string find_mount(const char* dir, bool is_root) {
+ if (is_root) {
+ return find_fstab_mount(dir);
} else {
return find_proc_mount(dir);
}
@@ -86,17 +86,29 @@
if (!directory_exists(dir)) {
return true;
}
- std::string dev = find_mount(dir);
- if (dev.empty()) {
+ bool is_root = strcmp(dir, "/") == 0;
+ std::string dev = find_mount(dir, is_root);
+ // Even if the device for the root is not found, we still try to remount it
+ // as rw. This typically only happens when running Android in a container:
+ // the root will almost always be in a loop device, which is dynamic, so
+ // it's not convenient to put in the fstab.
+ if (dev.empty() && !is_root) {
return true;
}
- if (!make_block_device_writable(dev)) {
+ if (!dev.empty() && !make_block_device_writable(dev)) {
WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
dir, dev.c_str(), strerror(errno));
return false;
}
+ if (mount(dev.c_str(), dir, "none", MS_REMOUNT | MS_BIND, nullptr) == -1) {
+ // This is useful for cases where the superblock is already marked as
+ // read-write, but the mount itself is read-only, such as containers
+ // where the remount with just MS_REMOUNT is forbidden by the kernel.
+ WriteFdFmt(fd, "remount of the %s mount failed: %s.\n", dir, strerror(errno));
+ return false;
+ }
if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
- WriteFdFmt(fd, "remount of %s failed: %s\n", dir, strerror(errno));
+ WriteFdFmt(fd, "remount of the %s superblock failed: %s\n", dir, strerror(errno));
return false;
}
return true;