Messages in this thread |  | | From | Daniel Phillips <> | Subject | Re: Why side-effects on open(2) are evil. (was Re: [RFD w/info-PATCH]device arguments from lookup) | Date | Thu, 24 May 2001 23:07:57 +0200 |
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On Tuesday 22 May 2001 22:10, Andreas Dilger wrote: > Peter Braam writes: > > File system journal recovery can corrupt a snapshot, because it > > copies data that needs to be preserved in a snapshot. During > > journal replay such data may be copied again, but the source can > > have new data already. > > The way it is implemented in reiserfs is to wait for existing > transactions to complete, entirely flush the journal and block all > new transactions from starting. Stephen implemented a journal flush > API to do this for ext3, but the hooks to call it from LVM are not in > place yet. This way the journal is totally empty at the time the > snapshot is done, so the read-only copy does not need to do journal > recovery, so no problems can arise.
I suppose I'm just reiterating the obvious, but we should eventually have a generic filesystem transaction API at the VFS level, once we have enough data points to know what the One True API should be.
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