On Tue, 01 Aug 2006 15:24:37 +0400 "Vladimir V. Saveliev" <[EMAIL PROTECTED]> wrote:
> > >The writeout code is ugly, although that's largely due to a mismatch > > >between > > >what reiser4 wants to do and what the VFS/MM expects it to do. > > Yes. reiser4 writeouts atoms. Most of pages get into atoms via > sys_write. But pages dirtied via shared mapping do not. They get into > atoms in reiser4's writepages address space operation. It think you mean ->writepage - reiser4 desn't implement ->writepages(). I assume you considered hooking into ->set_page_dirty() to do the add-to-atom thing earlier on? We'll merge mm-tracking-shared-dirty-pages.patch into 2.6.19-rc1, which would make that approach considerably more successful, I expect. ->set_page_dirty() is a bit awkward because it can be called under spinlock. Maybe comething could also be gained from the new vm_operations_struct.page_mkwrite(), although that's less obvious... > That is why > reiser4_sync_inodes has two steps: on first one it calls > generic_sync_sb_inodes to call writepages for dirty inodes to capture > pages dirtied via shared mapping into atoms. Second step flushes atoms. > > > > > > I agree --- both with it being ugly, and that being part of why. > > > > > If it > > >works, we can live with it, although perhaps the VFS could be made smarter. > > > > > > > > I would be curious regarding any ideas on that. Next time I read > > through that code, I will keep in mind that you are open to making VFS > > changes if it improves things, and I will try to get clever somehow and > > send it by you. Our squalloc code though is I must say the most > > complicated and ugliest piece of code I ever worked on for which every > > cumulative ugliness had a substantive performance advantage requiring us > > to keep it. If you spare yourself from reading that, it is > > understandable to do so. > > > > >I'd say that resier4's major problem is the lack of xattrs, acls and > > >direct-io. That's likely to significantly limit its vendor uptake. > > xattrs is really a problem. That's not good. The ability to properly support SELinux is likely to be important.
