Re: xfs_fsr allocation group optimization

[David Chinner <dgc@sgi.com>]

On Tue, Jun 12, 2007 at 09:07:36AM +1000, Nathan Scott wrote:
> On Mon, 2007-06-11 at 08:58 -0700, Chris Wedgwood wrote:
> > > In the way xfs_fsr operates now, in almost all user space, I don't
> > > see any good way to tell XFS where to place the extents, other than
> > > creating the temporary file in the same directory as the original
> > > file.
> > 
> > Exactly.
> > 
> > > My question is really, is there a better way than "find -xdev -inum"
> > > to find what file points to a given inode?
> > 
> > You can build then entire tree in-core using bulkstat and readdir,
> > doing the bulkstat first means you can try to optimize the order you
> > do the readdirs in somewhat.
> 
> Probably better to change the kernel extent-swap code to not do
> alloc-near-tempinode allocations, and instead find a way to pass
> XFS_ALLOCTYPE_THIS_AG/XFS_ALLOCTYPE_NEAR_BNO/or some saner alloc
> flag down to the allocator for all extent swapping allocations.

/me sighs and points to the generic allocation interface I wanted
for exactly these reasons:

http://marc.info/?l=linux-fsdevel&m=116278169519095&w=2

Instead, we're getting a mostly useless XFS_IOC_RESVSP replacement
called sys_fallocate() that provides us with pretty much nothing.
Given that sys_fallocate() can't be extended to do this sort of
thing, we're going to be stuck with doing our own thing again....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group