src/java.base/share/classes/sun/nio/ch/FileChannelImpl.java

rev 16220 : 8168628: (fc) SIGBUS when extending file size to map it
Summary: Synchronize file extension and subsequent map0(); on Linux use fallocate64() instead of ftruncate64().
Reviewed-by: rehn, simonis, alanb

*** 1,7 ****
  /*
!  * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
*** 896,905 ****
--- 896,908 ----
              begin();
              ti = threads.add();
              if (!isOpen())
                  return null;
  
+             long mapSize;
+             int pagePosition;
+             synchronized (positionLock) {
                  long filesize;
                  do {
                      filesize = nd.size(fd);
                  } while ((filesize == IOStatus.INTERRUPTED) && isOpen());
                  if (!isOpen())
*** 910,943 ****
                      throw new IOException("Channel not open for writing " +
                          "- cannot extend file to required size");
                  }
                  int rv;
                  do {
!                     rv = nd.truncate(fd, position + size);
                  } while ((rv == IOStatus.INTERRUPTED) && isOpen());
                  if (!isOpen())
                      return null;
              }
              if (size == 0) {
                  addr = 0;
                  // a valid file descriptor is not required
                  FileDescriptor dummy = new FileDescriptor();
                  if ((!writable) || (imode == MAP_RO))
                      return Util.newMappedByteBufferR(0, 0, dummy, null);
                  else
                      return Util.newMappedByteBuffer(0, 0, dummy, null);
              }
  
!             int pagePosition = (int)(position % allocationGranularity);
              long mapPosition = position - pagePosition;
!             long mapSize = size + pagePosition;
              try {
!                 // If no exception was thrown from map0, the address is valid
                  addr = map0(imode, mapPosition, mapSize);
              } catch (OutOfMemoryError x) {
!                 // An OutOfMemoryError may indicate that we've exhausted memory
!                 // so force gc and re-attempt map
                  System.gc();
                  try {
                      Thread.sleep(100);
                  } catch (InterruptedException y) {
                      Thread.currentThread().interrupt();
--- 913,947 ----
                          throw new IOException("Channel not open for writing " +
                              "- cannot extend file to required size");
                      }
                      int rv;
                      do {
!                         rv = nd.allocate(fd, position + size);
                      } while ((rv == IOStatus.INTERRUPTED) && isOpen());
                      if (!isOpen())
                          return null;
                  }
+ 
                  if (size == 0) {
                      addr = 0;
                      // a valid file descriptor is not required
                      FileDescriptor dummy = new FileDescriptor();
                      if ((!writable) || (imode == MAP_RO))
                          return Util.newMappedByteBufferR(0, 0, dummy, null);
                      else
                          return Util.newMappedByteBuffer(0, 0, dummy, null);
                  }
  
!                 pagePosition = (int)(position % allocationGranularity);
                  long mapPosition = position - pagePosition;
!                 mapSize = size + pagePosition;
                  try {
!                     // If map0 did not throw an exception, the address is valid
                      addr = map0(imode, mapPosition, mapSize);
                  } catch (OutOfMemoryError x) {
!                     // An OutOfMemoryError may indicate that we've exhausted
!                     // memory so force gc and re-attempt map
                      System.gc();
                      try {
                          Thread.sleep(100);
                      } catch (InterruptedException y) {
                          Thread.currentThread().interrupt();
*** 947,956 ****
--- 951,961 ----
                      } catch (OutOfMemoryError y) {
                          // After a second OOME, fail
                          throw new IOException("Map failed", y);
                      }
                  }
+             } // synchronized
  
              // On Windows, and potentially other platforms, we need an open
              // file descriptor for some mapping operations.
              FileDescriptor mfd;
              try {