libsnapshot: Add helpers for accessing CowOperation offsets.
These helpers avoid manual inspection of CowOperation::source, and
fiddling with block sizes.
Bug: 280529365
Test: cow_api_test
vts_libsnapshot_test
apply OTA
Change-Id: I1ba276e155eb8232a3115066caaa11030c171e11
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
index f599501..d0369e5 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
@@ -73,8 +73,20 @@
// The operation pointer must derive from ICowOpIter::Get().
virtual ssize_t ReadData(const CowOperation* op, void* buffer, size_t buffer_size,
size_t ignore_bytes = 0) = 0;
+
+ // Get the absolute source offset, in bytes, of a CowOperation. Returns
+ // false if the operation does not read from source partitions.
+ virtual bool GetSourceOffset(const CowOperation* op, uint64_t* source_offset) = 0;
};
+static constexpr uint64_t GetBlockFromOffset(const CowHeader& header, uint64_t offset) {
+ return offset / header.block_size;
+}
+
+static constexpr uint64_t GetBlockRelativeOffset(const CowHeader& header, uint64_t offset) {
+ return offset % header.block_size;
+}
+
// Iterate over a sequence of COW operations. The iterator is bidirectional.
class ICowOpIter {
public:
@@ -119,6 +131,7 @@
bool VerifyMergeOps() override;
bool GetFooter(CowFooter* footer) override;
bool GetLastLabel(uint64_t* label) override;
+ bool GetSourceOffset(const CowOperation* op, uint64_t* source_offset) override;
// Create a CowOpIter object which contains footer_.num_ops
// CowOperation objects. Get() returns a unique CowOperation object
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index 4ac89ae..cffc8de 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -312,19 +312,15 @@
std::unordered_map<uint64_t, const CowOperation*> overwritten_blocks;
while (!itr->AtEnd()) {
const auto& op = itr->Get();
- uint64_t block;
- bool offset;
- if (op->type == kCowCopyOp) {
- block = op->source;
- offset = false;
- } else if (op->type == kCowXorOp) {
- block = op->source / header_.block_size;
- offset = (op->source % header_.block_size) != 0;
- } else {
+ uint64_t offset;
+ if (!GetSourceOffset(op, &offset)) {
itr->Next();
continue;
}
+ uint64_t block = GetBlockFromOffset(header_, offset);
+ bool misaligned = (GetBlockRelativeOffset(header_, offset) != 0);
+
const CowOperation* overwrite = nullptr;
if (overwritten_blocks.count(block)) {
overwrite = overwritten_blocks[block];
@@ -332,7 +328,7 @@
<< op << "\noverwritten by previously merged op:\n"
<< *overwrite;
}
- if (offset && overwritten_blocks.count(block + 1)) {
+ if (misaligned && overwritten_blocks.count(block + 1)) {
overwrite = overwritten_blocks[block + 1];
LOG(ERROR) << "Invalid Sequence! Block needed for op:\n"
<< op << "\noverwritten by previously merged op:\n"
@@ -622,5 +618,18 @@
return decompressor->Decompress(buffer, buffer_size, header_.block_size, ignore_bytes);
}
+bool CowReader::GetSourceOffset(const CowOperation* op, uint64_t* source_offset) {
+ switch (op->type) {
+ case kCowCopyOp:
+ *source_offset = op->source * header_.block_size;
+ return true;
+ case kCowXorOp:
+ *source_offset = op->source;
+ return true;
+ default:
+ return false;
+ }
+}
+
} // namespace snapshot
} // namespace android
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp
index f9cdbc0..a3e40d9 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp
@@ -155,7 +155,12 @@
}
if (op) {
- chunk = op->source;
+ uint64_t source_offset;
+ if (!cow_->GetSourceOffset(op, &source_offset)) {
+ LOG(ERROR) << "GetSourceOffset failed in CompressedSnapshotReader for op: " << *op;
+ return false;
+ }
+ chunk = GetBlockFromOffset(cow_->GetHeader(), source_offset);
}
off64_t offset = (chunk * block_size_) + start_offset;
@@ -179,7 +184,12 @@
return -1;
}
- off64_t offset = op->source + start_offset;
+ uint64_t source_offset;
+ if (!cow_->GetSourceOffset(op, &source_offset)) {
+ LOG(ERROR) << "GetSourceOffset failed in CompressedSnapshotReader for op: " << *op;
+ return false;
+ }
+ off64_t offset = source_offset + start_offset;
std::string data(bytes_to_read, '\0');
if (!android::base::ReadFullyAtOffset(fd, data.data(), data.size(), offset)) {
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
index 922df34..559dcc7 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
@@ -115,12 +115,13 @@
SNAP_LOG(ERROR) << "ReadFromBaseDevice: Failed to get payload buffer";
return false;
}
- SNAP_LOG(DEBUG) << " ReadFromBaseDevice...: new-block: " << cow_op->new_block
- << " Source: " << cow_op->source;
- uint64_t offset = cow_op->source;
- if (cow_op->type == kCowCopyOp) {
- offset *= BLOCK_SZ;
+ uint64_t offset;
+ if (!reader_->GetSourceOffset(cow_op, &offset)) {
+ SNAP_LOG(ERROR) << "ReadFromBaseDevice: Failed to get source offset";
+ return false;
}
+ SNAP_LOG(DEBUG) << " ReadFromBaseDevice...: new-block: " << cow_op->new_block
+ << " Source: " << offset;
if (!android::base::ReadFullyAtOffset(backing_store_fd_, buffer, BLOCK_SZ, offset)) {
SNAP_PLOG(ERROR) << "Copy op failed. Read from backing store: " << backing_store_device_
<< "at block :" << offset / BLOCK_SZ << " offset:" << offset % BLOCK_SZ;
@@ -508,7 +509,7 @@
if (read_ahead_buffer_map.find(cow_op->new_block) == read_ahead_buffer_map.end()) {
SNAP_LOG(ERROR)
<< " Block: " << cow_op->new_block << " not found in read-ahead cache"
- << " Source: " << cow_op->source;
+ << " Op: " << *cow_op;
return -1;
}
// If this is a final block merged in the read-ahead buffer
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp
index 7858216..44b7319 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp
@@ -94,12 +94,13 @@
SNAP_LOG(ERROR) << "ReadFromBaseDevice: Failed to get payload buffer";
return false;
}
- SNAP_LOG(DEBUG) << " ReadFromBaseDevice...: new-block: " << cow_op->new_block
- << " Source: " << cow_op->source;
- uint64_t offset = cow_op->source;
- if (cow_op->type == kCowCopyOp) {
- offset *= BLOCK_SZ;
+ uint64_t offset;
+ if (!reader_->GetSourceOffset(cow_op, &offset)) {
+ SNAP_LOG(ERROR) << "ReadFromSourceDevice: Failed to get source offset";
+ return false;
}
+ SNAP_LOG(DEBUG) << " ReadFromBaseDevice...: new-block: " << cow_op->new_block
+ << " Op: " << *cow_op;
if (!android::base::ReadFullyAtOffset(backing_store_fd_, buffer, BLOCK_SZ, offset)) {
std::string op;
if (cow_op->type == kCowCopyOp)
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
index af24286..399f7b8 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
@@ -34,14 +34,17 @@
}
void ReadAhead::CheckOverlap(const CowOperation* cow_op) {
- uint64_t source_block = cow_op->source;
- uint64_t source_offset = 0;
- if (cow_op->type == kCowXorOp) {
- source_block /= BLOCK_SZ;
- source_offset = cow_op->source % BLOCK_SZ;
+ uint64_t source_offset;
+ if (!reader_->GetSourceOffset(cow_op, &source_offset)) {
+ SNAP_LOG(ERROR) << "ReadAhead operation has no source offset: " << *cow_op;
+ return;
}
+
+ uint64_t source_block = GetBlockFromOffset(header_, source_offset);
+ bool misaligned = (GetBlockRelativeOffset(header_, source_offset) != 0);
+
if (dest_blocks_.count(cow_op->new_block) || source_blocks_.count(source_block) ||
- (source_offset > 0 && source_blocks_.count(source_block + 1))) {
+ (misaligned && source_blocks_.count(source_block + 1))) {
overlap_ = true;
}
@@ -66,11 +69,12 @@
// Get the first block with offset
const CowOperation* cow_op = GetRAOpIter();
- *source_offset = cow_op->source;
- if (cow_op->type == kCowCopyOp) {
- *source_offset *= BLOCK_SZ;
- } else if (cow_op->type == kCowXorOp) {
+ if (!reader_->GetSourceOffset(cow_op, source_offset)) {
+ SNAP_LOG(ERROR) << "PrepareNextReadAhead operation has no source offset: " << *cow_op;
+ return nr_consecutive;
+ }
+ if (cow_op->type == kCowXorOp) {
xor_op_vec.push_back(cow_op);
}
@@ -88,10 +92,10 @@
*/
while (!RAIterDone() && num_ops) {
const CowOperation* op = GetRAOpIter();
- uint64_t next_offset = op->source;
-
- if (cow_op->type == kCowCopyOp) {
- next_offset *= BLOCK_SZ;
+ uint64_t next_offset;
+ if (!reader_->GetSourceOffset(op, &next_offset)) {
+ SNAP_LOG(ERROR) << "PrepareNextReadAhead operation has no source offset: " << *cow_op;
+ break;
}
// Check for consecutive blocks
@@ -803,6 +807,7 @@
if (!reader_->InitForMerge(std::move(cow_fd_))) {
return false;
}
+ header_ = reader_->GetHeader();
return true;
}
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.h b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.h
index 5e94de0..d3ba126 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.h
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.h
@@ -85,6 +85,7 @@
std::shared_ptr<SnapshotHandler> snapuserd_;
std::unique_ptr<CowReader> reader_;
+ CowHeader header_;
std::unordered_set<uint64_t> dest_blocks_;
std::unordered_set<uint64_t> source_blocks_;