Mark block device as read-only before mounting.
Mounting a block device as read-only still allows the filesystem to
write to the block device, while keeping the user-facing filesystem
interface "read-only". This behavior will make dm-verity to fail after
reboot if any block is modified during postinstall.
This patch marks the block device as read-only before mounting it, and
marks them read-only or read-write before using them during the update.
Bug: 27859604
TEST=Added logging and deployed an update to brillo, devices are marked RO/RW as needed during a delta update.
Change-Id: I781293cc0b3447dac708470ba6efad4103bf2a58
diff --git a/common/utils.h b/common/utils.h
index dbf92d2..3af6e71 100644
--- a/common/utils.h
+++ b/common/utils.h
@@ -178,6 +178,10 @@
// /dev/sda3. Return empty string on error.
std::string MakePartitionNameForMount(const std::string& part_name);
+// Set the read-only attribute on the block device |device| to the value passed
+// in |read_only|. Return whether the operation succeeded.
+bool SetBlockDeviceReadOnly(const std::string& device, bool read_only);
+
// Synchronously mount or unmount a filesystem. Return true on success.
// When mounting, it will attempt to mount the device as the passed filesystem
// type |type|, with the passed |flags| options. If |type| is empty, "ext2",