From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: To: Christoph Hellwig Cc: axboe@kernel.dk, martin.petersen@oracle.com, philipp.reisner@linbit.com, lars.ellenberg@linbit.com, target-devel@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, drbd-dev@lists.linbit.com, dm-devel@redhat.com Subject: Re: remove REQ_OP_WRITE_SAME From: "Martin K. Petersen" References: <20170412084809.8245-1-hch@lst.de> Date: Thu, 13 Apr 2017 22:23:10 -0400 In-Reply-To: <20170412084809.8245-1-hch@lst.de> (Christoph Hellwig's message of "Wed, 12 Apr 2017 10:48:01 +0200") Message-ID: MIME-Version: 1.0 Content-Type: text/plain List-ID: Christoph, > Now that we are using REQ_OP_WRITE_ZEROES for all zeroing needs in the > kernel there is very little use left for REQ_OP_WRITE_SAME. We only > have two callers left, and both just export optional protocol features > to remote systems: DRBD and the target code. While I'm not particularly married to WRITE SAME, I do think it's a shame that the RAID5/6 code never started using it. It does make a difference when initializing RAID sets. The other thing that keeps me a bit on the fence is that a bunch of the plumbing to handle a bio with a payload different from bi_size is needed for the copy offload token. I'm hoping to have those patches ready for 4.13. Right now there are a bunch of places where handling of REQ_OP_COPY_IN and REQ_OP_COPY_OUT share conditionals with WRITE SAME. So I suggest postponing the decision about whether to rip out WRITE SAME until I finish the token stuff. -- Martin K. Petersen Oracle Linux Engineering