On Mon, Sep 17, 2018 at 10:53:44PM +0200, Christoph Hellwig wrote: > Hi all, > > this series starts with a for-4.19 fix originally from Dave, and then > has various tweaks, including a fix for a potential uninitialized data > exposure that are 4.20 material. Nice! I'll get the fix ready for 4.19-rc5 and look at the rest for the 4.20 tree. Do you have any numbers that demonstrate the performance impact of the preallocation change? We've always intended to fix this exposure issue as you've done, I'm just interested in the sort of impact it has (if any). Allowing extent size hints to use delalloc should substantially improve performance for workloads that use extent size hints, so I don't expect the news to be all bad. :) Also, with this change to use unwritten extents for all delalloc extents, we can start doing speculative preallocation for writes into holes inside EOF without leaving uninitialised/unzeroed blocks laying around. Using spec. prealloc for "extend-via-truncate, sequential write to fill hole" workloads would greatly benefit from that. Did you have any plans to look at that code? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
