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Merge "Change the remount command to be more container-friendly"

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am: d24c8484c8

Change-Id: I878aa9f99481ba1cc2b358d163e6a396ef7c39a9
This commit is contained in:
Luis Hector Chavez 2018-02-28 17:00:15 +00:00 committed by android-build-merger
commit 677288c80a
1 changed files with 19 additions and 7 deletions
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26
adb/remount_service.cpp
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@ -62,9 +62,9 @@ static std::string find_fstab_mount(const char* dir) {
// 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 @@ static bool remount_partition(int fd, const char* dir) {
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;