RFR: 8232861: (fc) FileChannel.force fails on WebDAV file systems (macOS) [v2]

[Alan Bateman]

On Wed, 7 Apr 2021 16:37:27 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Apparently `fcntl(fd, F_FULLFSYNC)` can fail with `ENOTTY` in addition to `ENOTSUP` although it is not so documented. The `ioctl()` case is documented as
>> [ENOTTY]       fildes is not associated with a character special
>>                device.
>> [ENOTTY]       The specified request does not apply to the kind of
>>                object that the descriptor fildes references.
>> 
>> This request proposes to catch `ENOTTY` as well and fall back to `fsync(fd)`. The change was verified manually using a WebDAV server and no failures in CI test tiers 1-3 were observed. An alternative would be to fall back to `fsync(fd)` for **all** errors.
>
> Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8232861: Fallback on F_FULLSYNC if file is remote instead of if errno is ENOTTY

src/java.base/unix/native/libnio/ch/FileDispatcherImpl.c line 184:

> 182:                 result = fsync(fd);
> 183:             }
> 184:         }

Do you need to save/restore errno so that the original error from fcntl(F_FULLSYNC) is used in the error handling?

Also what you would think about dropping the check for ENOTSUP.

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PR: https://git.openjdk.java.net/jdk/pull/3366