FSFS corrupted revfiles && APR minimal version?

[Erik Huelsmann <eh...@gmail.com>]

I just checked the APR site and the latest versions are 1.2.11 and
0.9.16. While checking their CHANGES files (respectively at
http://www.apache.org/dist/apr/CHANGES-APR-1.2 and
http://www.apache.org/dist/apr/CHANGES-APR-0.9), I noticed that there
are some fixes which are at least interesting for us. My question is:
Could these be related to the FSFS revfile corruptions we have seen
and if so, should we up our requirements?

1) "Fix file pointer position calculation in apr_file_writev()." (apr
0.9.14 and 1.2.9)
2) "Fix thread safety of assorted file_io functions" (apr 0.9.14 and 1.2.9)


Does anybody have an answer to these questions?

bye,


Erik.

PS:


Next to the 2 above, there's one for OS/X which we might want to
require to prevent BFI (Bad First Impression):

- "Define OS/X filesystem encoding as UTF-8" (apr 0.9.15 and 1.2.10)

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Re: FSFS corrupted revfiles && APR minimal version?

[Karl Fogel <kf...@red-bean.com>]

John Szakmeister <jo...@szakmeister.net> writes:
> 1) apr_file_writev doesn't appear to be used by SVN (a least that's
> what a quick grep has revealed).

I wouldn't believe a grep like that.  Often what happens is SVN calls
some other APR function, which then calls the one... that calls the
one... etc... and so on, until we get to the turtle in question.  The
question is not "Does the string 'apr_file_writev' appear in SVN?",
it's "Is there a call chain from SVN to 'apr_file_writev'?".  Grep
will not answer that question.

You may be right about the ultimate causes of the problems not being
in APR, I'm just saying don't count these grep results as evidence
toward that conclusion.

-K

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Re: FSFS corrupted revfiles && APR minimal version?

[John Szakmeister <jo...@szakmeister.net>]

Erik Huelsmann wrote:
> I just checked the APR site and the latest versions are 1.2.11 and
> 0.9.16. While checking their CHANGES files (respectively at
> http://www.apache.org/dist/apr/CHANGES-APR-1.2 and
> http://www.apache.org/dist/apr/CHANGES-APR-0.9), I noticed that there
> are some fixes which are at least interesting for us. My question is:
> Could these be related to the FSFS revfile corruptions we have seen
> and if so, should we up our requirements?
> 
> 1) "Fix file pointer position calculation in apr_file_writev()." (apr
> 0.9.14 and 1.2.9)
> 2) "Fix thread safety of assorted file_io functions" (apr 0.9.14 and 1.2.9)
> 
> 
> Does anybody have an answer to these questions?

I'm not sure I can really answer these questions, but I'll try.

1) apr_file_writev doesn't appear to be used by SVN (a least that's what 
a quick grep has revealed).

2) I'm not sure these matter either.

The root of the problem seems to stem around the fact that a network 
session can end (from some sort of error), but the associated pools 
aren't cleared before the client retries.  The end result is that the 
client is able to start writing new data to the file (with a new file 
object), and when the pool is finally cleaned up from the old session we 
end up with a corrupted rev (because data is flushed into the file).

So the problem seems to be ours and not APR's.

-John

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