On Fri, Sep 11, 2009 at 6:51 AM, Ryusuke Konishi <[email protected]> wrote:
> Hi Prasenjit Giri, and Reinoud, > On Thu, 10 Sep 2009 21:26:19 +0200, Reinoud Zandijk <wrote: > > Hi Prasenjit Giri, > > > > On Fri, Sep 11, 2009 at 12:46:04AM +0530, Prasenjit Giri wrote: > > > Even after looking through various sites, forums, mailing lists I could > not > > > uncover the present directoy management of NILFS2. > > > > > > As I see a B-tree directory management in your long term to do list, it > > > would be really nice if someone would ought to share the information > > > regarding the present directory management of NILFS2 > > > > Currently directories are recorded just as a sequential file but not > filled > > with user data but with dirent entries in their blocks like ext2fs does. > > Nothing special about that :) > > > > I dont know if b+tree directory management would be preferable though. > With > > some smart caching all directory operations can be made O(1) anyway. > > > > With regards, > > Reinoud Zandijk > > Yes, directory is a file and it's already managed with b-tree like > other files. However, the current directory design is not O(log n), > and is actually slow especially for file creation. > > So, it leaves room for considering the true "b-tree directory > management". > > OTOH, the replacement has the following points to notice: > > 1) It may complicate the log writer. > > The current log writer is designed on the basis that every data > and meta data is a file. In NILFS, inodes, segment usage state, > and checkpoints, are managed with correponding meta-data files. > > The true "b-tree directory management" may break this uniformity. > > 2) A disk format change is required. > (We can deem this a trade-off at this stage) > > This may be a -v3 material. But anyway, patch proposals are welcome. > > Thank you, > Ryusuke Konishi > Hello Reinoud Zandijk, Ryusuke Konishi This has been more than helpful as I was at complete lost. But with this new side of it could you explain the quoted, " --- true 'b-tree directory management' --- ". I've on this mail list, looking for ideas that would be feasible for an undergrad project -- though this adds a very unpleasant twist. Is writable snapshot feasible ? If so, is there an abstract for this purpose? Is it doable in a years time? Or could you all please suggest an alternative on such grounds. With regards, Prasenjit Giri Rajesh D. Yadav Ashwin Goel Sunil V. Chitkote -- Prasenjit Giri
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