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Commit ed1a7d5f authored by Daniel Zheng's avatar Daniel Zheng
Browse files

Add v3 Cow Header 

Adding Version 3 of CowHeader. This will inherit from original
CowHeader and add a compression field. We are no longer supporting
different compressions per operation so having this one field is enough.

Test: cow_api_test
Change-Id: If88dceda139807cc5e647b706ddeb2b3e83c024f
parent b3cd361b

fs_mgr/libsnapshot/include/libsnapshot/cow_format.h

+12 −0
Original line number Diff line number Diff line
@@ -91,6 +91,18 @@ struct CowHeader { 


    // Scratch space used during merge

    uint32_t buffer_size;



} __attribute__((packed));



struct CowHeaderV3 : public CowHeader {

    // Location of sequence buffer in COW.

    uint64_t sequence_buffer_offset;

    // Size, in bytes, of the CowResumePoint buffer.

    uint32_t resume_buffer_size;

    // Size, in bytes, of the CowOperation buffer.

    uint32_t op_buffer_size;

    // Compression Algorithm

    uint32_t compression_algorithm;

} __attribute__((packed));



// This structure is the same size of a normal Operation, but is repurposed for the footer.

fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.cpp

+2 −2
Original line number Diff line number Diff line
@@ -243,7 +243,7 @@ bool CowWriterV2::OpenForWrite() { 


    // Headers are not complete, but this ensures the file is at the right

    // position.

    if (!android::base::WriteFully(fd_, &header_, sizeof(header_))) {

    if (!android::base::WriteFully(fd_, &header_, sizeof(CowHeader))) {

        PLOG(ERROR) << "write failed";

        return false;

    }
@@ -262,7 +262,7 @@ bool CowWriterV2::OpenForWrite() { 
        return false;

    }



    if (lseek(fd_.get(), sizeof(header_) + header_.buffer_size, SEEK_SET) < 0) {

    if (lseek(fd_.get(), sizeof(CowHeader) + header_.buffer_size, SEEK_SET) < 0) {

        PLOG(ERROR) << "lseek failed";

        return false;

    }