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Commit 14ae4d1d authored by David Anderson's avatar David Anderson
Browse files

libsnapshot: Round compressed COW sizes to the nearest block. 

This is needed to create and stack device-mapper devices. The kernel
complains (or rejects) the table otherwise.

Bug: N/A
Test: manual test
Change-Id: I2bb3e55b7d999522c4c990b4ab7c46bcb78553a8
parent 56850e12

fs_mgr/libsnapshot/partition_cow_creator.cpp

+8 −1
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ using RepeatedPtrField = google::protobuf::RepeatedPtrField<T>; 
namespace android {

namespace snapshot {



static constexpr uint64_t kBlockSize = 4096;



using namespace android::storage_literals;



// Intersect two linear extents. If no intersection, return an extent with length 0.
@@ -149,7 +151,12 @@ uint64_t PartitionCowCreator::GetCowSize() { 


        // Add an extra 2MB of wiggle room for any minor differences in labels/metadata

        // that might come up.

        return update->estimate_cow_size() + 2_MiB;

        auto size = update->estimate_cow_size() + 2_MiB;



        // Align to nearest block.

        size += kBlockSize - 1;

        size &= ~(kBlockSize - 1);

        return size;

    }



    // WARNING: The origin partition should be READ-ONLY