Messages in this thread | | | Date | Fri, 13 Jan 2006 16:27:14 -0600 | From | Eric Van Hensbergen <> | Subject | Re: [PATCH]: v9fs: add readpage support |
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On 1/13/06, Andrew Morton <akpm@osdl.org> wrote: > Eric Van Hensbergen <ericvh@gmail.com> wrote: > > > > I went looking for an example of how to do this better. More or less, > > v9fs reads and writes are similar to DirectIO since they don't go > > through the page-cache. > > hm. Why not? >
At the moment we'd rather not cache anything with v9fs as it hides operations from the servers, and in the case of synthetic servers it can be a bad thing. There is a somewhat well-understood strategy for how to do cacheing of static files in a sane manner under 9P, but we were holding off on trying to move that into v9fs for the time being. The only reason we added the read-only mmap support back in was to support users who were trying to access executables over 9P connections.
> > > > Now, that being said, it still seems to me to be a bit heavy weight -- > > do folks have a better pointer to code that I can use as an example of > > how to do this more efficiently? > > Not really. If that's what you need to do then that's the way to do it. > We've had nasty races and other problems wrt invalidate_inode_pages2 and > pagefaults, so I suggest you test that mix carefully. > > Have you tried fsx-linux? It's really good for finding data integrity > bugs. There's a copy in > http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz. >
We've been regression testing with vanilla fsx, I'll upgrade to fsx-linux and make sure we are clean.
> > I'd suggest that you want the mapping->nrpages test - it'll be a useful > speedup in the common case. >
Yeah, as I was tracing through the invalidate_inode_pages2() this morning I realized this is probably a good idea. Should have a new patch to you by the end of the weekend.
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