[ccache] RE: [distcc] Fw: [NFS] nfs/mmap/rename file corruption

[Gavrie Philipson]

Hi Martin,

Fantastic -- it solved my problem with the corrupted object files.
Since the exports(5) manpage recommends using no_subtree_check for
rapidly changing filesystems anyway, this is not such a bad solution.

Thanks,

-- Gavrie
. 

> -----Original Message-----
> From: Martin Pool [mailto:mbp at sourcefrog.net] 
> Sent: Thursday, August 28, 2003 5:18
> To: distcc at lists.samba.org; ccache at lists.samba.org
> Subject: [distcc] Fw: [NFS] nfs/mmap/rename file corruption
> 
> 
> In summary: to make ccache work safely on an NFS filesystem, the
> filesystem must be exported with no_subtree_check.  Otherwise data can
> be lost when it renames recently-written files. :-(
> 
> 
> 
> ----------------------
> Begin forwarded message:
> 
> Date: 27 Aug 2003 21:37:38 -0400
> From: Trond Myklebust <trond.myklebust at fys.uio.no>
> To: Martin Pool <mbp at sourcefrog.net>
> Cc: nfs at lists.sourceforge.net
> Subject: Re: [NFS] nfs/mmap/rename file corruption
> 
> 
> >>>>> " " == Martin Pool <mbp at sourcefrog.net> writes:
> 
>      > - ccache runs distcc with output to a temporary file
>      >  - distcc opens, mmaps, writes to, munmaps, and closes the
> temporary     >    file
>      > - distcc exits
>      >  - ccache renames the temporary file to its proper location in
> the     >    ccache
>      > - ccache opens the file read only, and reads from it
> 
> Is this a rename from one directory to the other? If so, are you using
> the 'no_subtree_check' option on the server? Without the latter option
> enabled, I would indeed expect the behaviour that you describe.
> 
> Cheers,
>   Trond
> 
> 
> -- 
> Martin 
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