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8202261: (fc) FileChannel.map and RandomAccessFile.setLength should not preallocate space

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Reviewed-by: bpb
This commit is contained in:
Alan Bateman 2018-04-26 09:04:18 +01:00
parent ccc74fdd60
commit 2df7aa7b9f
9 changed files with 101 additions and 144 deletions
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21
src/java.base/unix/native/libjava/io_util_md.c
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2018, 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
@ -232,25 +232,6 @@ jint
handleSetLength(FD fd, jlong length)
{
int result;
#if defined(__linux__)
/*
* On Linux, if the file size is being increased, then ftruncate64()
* will modify the metadata value of the size without actually allocating
* any blocks which can cause a SIGBUS error if the file is subsequently
* memory-mapped.
*/
struct stat64 sb;
if (fstat64(fd, &sb) == 0 && length > sb.st_blocks*512) {
RESTARTABLE(fallocate64(fd, 0, 0, length), result);
// Return on success or if errno is neither EOPNOTSUPP nor ENOSYS
if (result == 0) {
return 0;
} else if (errno != EOPNOTSUPP && errno != ENOSYS) {
return result;
}
}
#endif
RESTARTABLE(ftruncate64(fd, length), result);
return result;
}