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Merge "Add CowOperationV2" into main

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Daniel Zheng 2023-09-18 21:30:29 +00:00 committed by Gerrit Code Review
commit a10bfe1d13
2 changed files with 36 additions and 1 deletions
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36
fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
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@ -143,6 +143,42 @@ struct CowOperation {
uint64_t source;
} __attribute__((packed));
// The on disk format of cow (currently == CowOperation)
struct CowOperationV2 {
// The operation code (see the constants and structures below).
uint8_t type;
// If this operation reads from the data section of the COW, this contains
// the compression type of that data (see constants below).
uint8_t compression;
// If this operation reads from the data section of the COW, this contains
// the length.
uint16_t data_length;
// The block of data in the new image that this operation modifies.
uint64_t new_block;
// The value of |source| depends on the operation code.
//
// For copy operations, this is a block location in the source image.
//
// For replace operations, this is a byte offset within the COW's data
// sections (eg, not landing within the header or metadata). It is an
// absolute position within the image.
//
// For zero operations (replace with all zeroes), this is unused and must
// be zero.
//
// For Label operations, this is the value of the applied label.
//
// For Cluster operations, this is the length of the following data region
//
// For Xor operations, this is the byte location in the source image.
uint64_t source;
} __attribute__((packed));
static_assert(sizeof(CowOperationV2) == sizeof(CowOperation));
static_assert(sizeof(CowOperation) == sizeof(CowFooterOperation));
static constexpr uint8_t kCowCopyOp = 1;

1
fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
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@ -165,7 +165,6 @@ class CowReader final : public ICowReader {
void UpdateMergeOpsCompleted(int num_merge_ops) { header_.num_merge_ops += num_merge_ops; }
private:
bool ParseOps(std::optional<uint64_t> label);
bool PrepMergeOps();
uint64_t FindNumCopyops();
uint8_t GetCompressionType(const CowOperation* op);