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Re: svn_io_file_flush_to_disk fails on AFS filesystems on Darwin

From: Branko Čibej <brane_at_apache.org>
Date: Thu, 27 Jun 2019 10:56:40 +0200

On 26.06.2019 20:57, Branko Čibej wrote:
> On 26.06.2019 18:41, Nathan Hartman wrote:
>> On Wed, Jun 26, 2019 at 11:49 AM Branko Čibej <brane_at_apache.org
>> <mailto:brane_at_apache.org>> wrote:
>>
>> On 26.06.2019 04:52, Quentin Smith wrote:
>> > svn_io_file_flush_to_disk in subversion/libsvn_subr/io.c fails to
>> > flush files on AFS filesystems on Darwin. The user-visible
>> experience is:
>>
>>
>> (snip)
>>
>> > The code ignores EINVAL with a comment about filesystems that don't
>> > support it; evidently on Darwin this also needs to include ENOTTY.
>> >
>> > (Also, I suspect it should fall back from fcntl to fsync, since I
>> > suspect fsync /does/ work on AFS filesystems.)
>>
>>
>> (snip)
>>
>> Last but not least, I do wish filesystems were consistent in their
>> implementation ... what on earth is ENOTTY doing here?
>>
>> -- Brane
>>
>>
>> Looks like libuv encountered similar issues and applied similar
>> handling to that in SQLite:
>>
>> https://github.com/libuv/libuv/commit/5b0e1d75a207bb1c662f4495c0d8ba1e81a5bb7d
>>
> Something tell me this should be solved in APR ...

Turns out that APR is already doing this _almost_ correctly. The kind of
change linked to above would fit in APR quite well. The "problem" is
that Subversion currently doesn't use the "new" APR functions for
sync/datasync. So my suggestion for the fix would be twofold:

  * Enhance the sync functionality in APR (trunk, 1.7 and possibly 1.6)
  * Change Subversion to use APR's sync functions

I'll look into this.

-- Brane
Received on 2019-06-27 10:56:46 CEST

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