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Re: svn commit: r1680819 - /subversion/trunk/subversion/libsvn_fs_fs/revprops.c

From: Philip Martin <philip.martin_at_wandisco.com>
Date: Thu, 21 May 2015 14:25:13 +0100

ivan_at_apache.org writes:

> Author: ivan
> Date: Thu May 21 11:00:43 2015
> New Revision: 1680819
>
> URL: http://svn.apache.org/r1680819
> Log:
> Prevent a possible FSFS repository corruption with power or network disk
> failures when changing revision properties. Perform a hardware flush
> after we finished writing to a temporary revprop file and before moving
> it into place. The change doesn't affect commit operation behavior.
>
> The corruption can be easily reproduced by triggering a power loss while
> performing svnsync.
>
> This change is somewhat similar to what we did in r1483781, but covers how
> we write revision property files. See related discussion in dev_at_s.a.o
> (Subject: "FSFS Repository corruption on high load on Windows [...] ") [1].
>
> Patch by: me
> kotkov
>
> [1] http://svn.haxx.se/dev/archive-2013-05/0245.shtml
>
> * subversion/libsvn_fs_fs/revprops.c
> (repack_stream_open): Rename the function ...
> (repack_file_open): ...to this. Rework it to return files (apr_file_t)
> instead of streams.
> (repack_revprops): Work with a file instead of a stream. Flush any
> unwritten data to disk before returning.
> (write_non_packed_revprop): Flush any unwritten data to disk after
> serializing the revision property list.
> (write_packed_revprop): Cope with the changes in repack_file_open() and
> repack_revprops() that now work with files. Flush the data to disk when
> done writing to a temporary manifest file.

Is that the best approach? In the past we have been moving away from
file code to stream code. Can we make the flush part of the stream
code? Perhaps we could create a "flushing stream" that just does flush
and then simply insert the new stream into the old code.

-- 
Philip Martin | Subversion Committer
WANdisco // *Non-Stop Data*
Received on 2015-05-21 15:26:22 CEST

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