HDFS-4660. Block corruption can happen during pipeline recovery. Contributed by Kihwal Lee.
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Kihwal Lee
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@ -1026,6 +1026,8 @@ Release 2.7.1 - UNRELEASED
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HDFS-8597. Fix TestFSImage#testZeroBlockSize on Windows. (Xiaoyu Yao)
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HDFS-4660. Block corruption can happen during pipeline recovery (kihwal)
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Release 2.7.0 - 2015-04-20
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INCOMPATIBLE CHANGES
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@ -588,29 +588,59 @@ private int receivePacket() throws IOException {
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try {
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long onDiskLen = replicaInfo.getBytesOnDisk();
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if (onDiskLen<offsetInBlock) {
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//finally write to the disk :
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// Normally the beginning of an incoming packet is aligned with the
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// existing data on disk. If the beginning packet data offset is not
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// checksum chunk aligned, the end of packet will not go beyond the
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// next chunk boundary.
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// When a failure-recovery is involved, the client state and the
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// the datanode state may not exactly agree. I.e. the client may
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// resend part of data that is already on disk. Correct number of
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// bytes should be skipped when writing the data and checksum
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// buffers out to disk.
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long partialChunkSizeOnDisk = onDiskLen % bytesPerChecksum;
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boolean alignedOnDisk = partialChunkSizeOnDisk == 0;
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boolean alignedInPacket = firstByteInBlock % bytesPerChecksum == 0;
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if (onDiskLen % bytesPerChecksum != 0) {
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// prepare to overwrite last checksum
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adjustCrcFilePosition();
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// Since data is always appended, not overwritten, partial CRC
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// recalculation is necessary if the on-disk data is not chunk-
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// aligned, regardless of whether the beginning of the data in
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// the packet is chunk-aligned.
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boolean doPartialCrc = !alignedOnDisk && !shouldNotWriteChecksum;
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// If this is a partial chunk, then verify that this is the only
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// chunk in the packet. If the starting offset is not chunk
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// aligned, the packet should terminate at or before the next
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// chunk boundary.
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if (!alignedInPacket && len > bytesPerChecksum) {
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throw new IOException("Unexpected packet data length for "
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+ block + " from " + inAddr + ": a partial chunk must be "
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+ " sent in an individual packet (data length = " + len
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+ " > bytesPerChecksum = " + bytesPerChecksum + ")");
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}
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// If this is a partial chunk, then read in pre-existing checksum
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// If the last portion of the block file is not a full chunk,
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// then read in pre-existing partial data chunk and recalculate
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// the checksum so that the checksum calculation can continue
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// from the right state.
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Checksum partialCrc = null;
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if (!shouldNotWriteChecksum && firstByteInBlock % bytesPerChecksum != 0) {
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if (doPartialCrc) {
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if (LOG.isDebugEnabled()) {
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LOG.debug("receivePacket for " + block
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+ ": bytesPerChecksum=" + bytesPerChecksum
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+ " does not divide firstByteInBlock=" + firstByteInBlock);
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+ ": previous write did not end at the chunk boundary."
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+ " onDiskLen=" + onDiskLen);
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}
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long offsetInChecksum = BlockMetadataHeader.getHeaderSize() +
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onDiskLen / bytesPerChecksum * checksumSize;
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partialCrc = computePartialChunkCrc(onDiskLen, offsetInChecksum);
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}
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// The data buffer position where write will begin. If the packet
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// data and on-disk data have no overlap, this will not be at the
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// beginning of the buffer.
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int startByteToDisk = (int)(onDiskLen-firstByteInBlock)
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+ dataBuf.arrayOffset() + dataBuf.position();
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// Actual number of data bytes to write.
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int numBytesToDisk = (int)(offsetInBlock-onDiskLen);
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// Write data to disk.
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@ -625,31 +655,63 @@ private int receivePacket() throws IOException {
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final byte[] lastCrc;
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if (shouldNotWriteChecksum) {
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lastCrc = null;
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} else if (partialCrc != null) {
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// If this is a partial chunk, then verify that this is the only
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// chunk in the packet. Calculate new crc for this chunk.
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if (len > bytesPerChecksum) {
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throw new IOException("Unexpected packet data length for "
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+ block + " from " + inAddr + ": a partial chunk must be "
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+ " sent in an individual packet (data length = " + len
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+ " > bytesPerChecksum = " + bytesPerChecksum + ")");
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} else {
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int skip = 0;
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byte[] crcBytes = null;
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// First, overwrite the partial crc at the end, if necessary.
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if (doPartialCrc) { // not chunk-aligned on disk
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// Calculate new crc for this chunk.
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int bytesToReadForRecalc =
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(int)(bytesPerChecksum - partialChunkSizeOnDisk);
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if (numBytesToDisk < bytesToReadForRecalc) {
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bytesToReadForRecalc = numBytesToDisk;
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}
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partialCrc.update(dataBuf.array(), startByteToDisk, numBytesToDisk);
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byte[] buf = FSOutputSummer.convertToByteStream(partialCrc, checksumSize);
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lastCrc = copyLastChunkChecksum(buf, checksumSize, buf.length);
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partialCrc.update(dataBuf.array(), startByteToDisk,
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bytesToReadForRecalc);
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byte[] buf = FSOutputSummer.convertToByteStream(partialCrc,
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checksumSize);
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crcBytes = copyLastChunkChecksum(buf, checksumSize, buf.length);
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// prepare to overwrite last checksum
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adjustCrcFilePosition();
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checksumOut.write(buf);
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if(LOG.isDebugEnabled()) {
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LOG.debug("Writing out partial crc for data len " + len);
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LOG.debug("Writing out partial crc for data len " + len +
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", skip=" + skip);
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}
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partialCrc = null;
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} else {
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// write checksum
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skip++; // For the partial chunk that was just read.
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}
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// Determine how many checksums need to be skipped up to the last
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// boundary. The checksum after the boundary was already counted
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// above. Only count the number of checksums skipped up to the
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// boundary here.
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long lastChunkBoundary = onDiskLen - (onDiskLen%bytesPerChecksum);
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long skippedDataBytes = lastChunkBoundary - firstByteInBlock;
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if (skippedDataBytes > 0) {
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skip += (int)(skippedDataBytes / bytesPerChecksum) +
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((skippedDataBytes % bytesPerChecksum == 0) ? 0 : 1);
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}
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skip *= checksumSize; // Convert to number of bytes
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// write the rest of checksum
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final int offset = checksumBuf.arrayOffset() +
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checksumBuf.position();
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final int end = offset + checksumLen;
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lastCrc = copyLastChunkChecksum(checksumBuf.array(), checksumSize,
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end);
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checksumOut.write(checksumBuf.array(), offset, checksumLen);
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checksumBuf.position() + skip;
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final int end = offset + checksumLen - skip;
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// If offset > end, there is no more checksum to write.
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// I.e. a partial chunk checksum rewrite happened and there is no
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// more to write after that.
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if (offset > end) {
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assert crcBytes != null;
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lastCrc = crcBytes;
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} else {
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final int remainingBytes = checksumLen - skip;
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lastCrc = copyLastChunkChecksum(checksumBuf.array(),
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checksumSize, end);
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checksumOut.write(checksumBuf.array(), offset, remainingBytes);
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}
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}
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/// flush entire packet, sync if requested
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