Re: XFS and O_STREAMING

[Steve Lord <lord@sgi.com>]

On Mon, 2002-12-09 at 12:01, Buzbee, James wrote:
> I've been looking at Robert Love's O_STREAMING patch for the kernel :
> 
> http://www.kernel.org/pub/linux/kernel/people/rml/O_STREAMING/v2.4/O_STREAMING-rml-2.4.20-pre9-1.patch
> 
> I find that it doesn't quite work as expected with XFS.  It patches the 
> generic_file_read/write routines to drop pages from cache list when a 
> file is marked as O_STREAMING, but it appears to me as if XFS doesn't 
> use the generic_file_write routine, but has its own version.
> 
> I have a few questions. First, does this patch make sense for XFS? 
> Could XFS's version of the generic_file_write routine be patched the 
> same way?  Or perhaps there is an equivalent way to accomplish the same 
> thing using standard XFS.

We do use generic_file_write, it is just buried underneath our own
layer. O_STREAMING sounds like the old dropbehind stuff and should
work just fine.

One issue is that we do allocation of the actual blocks at flush time,
we end up in writepage rather than in submit_bh. 

Steve

-- 

Steve Lord                                      voice: +1-651-683-3511
Principal Engineer, Filesystem Software         email: lord@sgi.com