Re: [RFC] basic delayed allocation in VFS

[Mingming Cao <cmm@us.ibm.com>]

On Sun, 2007-07-29 at 20:24 +0100, Christoph Hellwig wrote:
> On Sun, Jul 29, 2007 at 11:30:36AM -0600, Andreas Dilger wrote:
> > Sigh, we HAVE a patch that was only adding delalloc to ext4, but it
> > was rejected because "that functionality should go into the VFS".
> > Since the performance improvement of delalloc is quite large, we'd
> > like to get this into the kernel one way or another.  Can we make a
> > decision if the ext4-specific delalloc is acceptable?
> 
> I'm a big proponent of having proper common delalloc code, but the
> one proposed here is not generic for the existing filesystem using
> delalloc.  

To be fair, what Alex have so far is probably good enough for ext2/3
delayed allocation.

> It's still on my todo list to revamp the xfs code to get
> rid of some of the existing mess and make it useable genericly.  If
> the ext4 users are fine with the end result we could move to generic
> code.
> 

Are you okay with having a ext4 delayed allocation implementation (i.e.
moving the code proposed in this thread to fs/ext4) first?  Then later
when you come up with a generic delayed allocation for both ext4 and xfs
we could make use of that generic implementation. Is that a acceptable
approach? 

Andrew, what do you think?


Regards,
Mingming