Re: Fixing the FSFS corruption bug

Malcolm Rowe <malcolm-svn-dev@farside.org.uk> writes:

> On Tue, Sep 05, 2006 at 09:29:27PM +0100, Malcolm Rowe wrote:
>> + err = svn_io_file_open(file, path_txn_proto_rev_lock(fs, txn_id, pool),
>> + APR_WRITE | APR_CREATE | APR_EXCL, APR_OS_DEFAULT,
>> + pool);
>
> So I've just noticed that this method of creating a lockfile (using
> O_CREATE|O_EXCL) appears to be broken on NFSv3 mounts on Linux pre-2.6.5
> (including all 2.4 kernels), as described in [1], and as far as I can
> tell, isn't supported on NFSv2 at all ([2] backs this up, to some extent).

I suppose you might be able to use some sort of rename system instead
of using a separate lock file: rename the file before writing it and
then rename it back when the write is complete. An incomplete write
would leave the renamed file which a subsequent write would need to
delete.

-- 
Philip Martin
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