On 2019/6/27 下午10:58, David Sterba wrote: > On Tue, Jun 25, 2019 at 04:24:57PM +0800, Qu Wenruo wrote: >> Ping? >> >> This patch should fix the problem of compressed extent even when >> nodatasum is set. >> >> It has been one year but we still didn't get a conclusion on where >> force_compress should behave. > > Note that pings to patches sent year ago will get lost, I noticed only > because you resent it and I remembered that we had some discussions, > without conclusions. > >> But at least to me, NODATASUM is a strong exclusion for compress, no >> matter whatever option we use, we should NEVER compress data without >> datasum/datacow. > > That's correct, but the way you fix it is IMO not right. This was also > noticed by Nikolay, that there are 2 locations that call > inode_need_compress but with different semantics. > > One is the decision if compression applies at all,
> and the second one > when that's certain it's compression, to do it or not based on the > status decision of eg. heuristics. The second call is in compress_file_extent(), with inode_need_compress() return 0 for NODATACOW/NODATASUM inodes, we will not go into cow_file_range_async() branch at all. So would you please explain how this could cause problem? To me, prevent the problem in inode_need_compress() is the safest location. Thanks, Qu
signature.asc
Description: OpenPGP digital signature
