Messages in this thread | | | Date | Thu, 4 Sep 2003 16:03:44 -0600 | From | Andreas Dilger <> | Subject | Re: precise characterization of ext3 atomicity |
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On Sep 05, 2003 01:32 +0400, Hans Reiser wrote: > Andreas Dilger wrote: > >It is possible to do the same with ext3, namely exporting journal_start() > >and journal_stop() (or some interface to them) to userspace so the application > >can start a transaction for multiple operations. We had discussed this in > >the past, but decided not to do so because user applications can screw up in > >so many ways, and if an application uses these interfaces it is possible to > >deadlock the entire filesystem if the application isn't well behaved. > > That's why we confine it to a (finite #defined number) set of > operations within one sys_reiser4 call. At some point we will allow > trusted user space processes to span multiple system calls (mail server > applicances, database appliances, etc., might find this useful). You > might consider supporting sys_reiser4 at some point.
Ah, OK. If you are confining the atom to a single syscall, then this is a much easier problem to solve, assuming sys_reiser4() has a sufficiently rich interface to express what people want to do. It avoids all of the potential problems that could arise if you want to keep a transaction open over multiple syscalls.
Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/
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