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Re: ext3 and chattr +S on postfix spools



Hi,

On Tue, Feb 05, 2002 at 03:39:34PM +0100, Erik Smit wrote:
> On Tue, 2002-02-05 at 15:26, Wietse Venema wrote:

> > > > maildir delivery requires that certain file system operations are
> > > > atomic and synchronous.
> > > > [...]
> > > > Translated into ext3 speak that means: the link and unlink operations
> > > > are written to the log before the respective system call returns.
> > > 
> > > Excuse my ignorance, but since it has been written to log and the
> > > machine would crash before the systemcall returns wouldn't this mean it
> > > would be recovered (by journal replaying) during boot?
> > 
> > IFF the information is written to the ON DISK log, then the
> > recovery is possible.
> 
> Wasn't that the whole point to journaling filesystems (and chattr +S)?

Yes.  ext3 will always do this on synchronous directories.
Synchronous IO is *always* guaranteed to be persistent on disk on
return, and ext3 also makes firm atomicity guarantees about all
deletes, renames etc.  (Incidentally, ffs does not --- renames across
directories are not atomic on ffs.)

Cheers,
 Stephen





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