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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20230308143754.1976726-1-dhowells@redhat.com> <20230308143754.1976726-4-dhowells@redhat.com> To: Miklos Szeredi Cc: dhowells@redhat.com, Jens Axboe , Al Viro , Christoph Hellwig , Matthew Wilcox , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , John Hubbard , linux-unionfs@vger.kernel.org Subject: Re: [PATCH v16 03/13] overlayfs: Implement splice-read MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2011734.1678290876.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Wed, 08 Mar 2023 15:54:36 +0000 Message-ID: <2011735.1678290876@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Rspamd-Queue-Id: 2B5C940018 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: afqndykpck93jnzp9huygfngum5qchc6 X-HE-Tag: 1678290884-741544 X-HE-Meta: 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 P8/H1Z7G 7Hl1Nl3HMqsdJodspmRg5I+nCTCWkgP3Bp8XV2NS9AB4aD7DTc/476tba56yyu4Kynu+gSS08A0AznyaMtPAfLj1mx6u3W638A5XA9pOCaxRg15QNuByao/Wj86GzakSDvDDAtG2T7nh0oHT0Sc+U8yIIlyYnP/DUizLkZPLkWDo0WFA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Miklos Szeredi wrote: > > + ret =3D -EINVAL; > > + if (!real.file->f_op->splice_read) > > + goto out_fdput; > > + > > + ret =3D rw_verify_area(READ, real.file, ppos, len); > > + if (unlikely(ret < 0)) > > + goto out_fdput; > > + > > + old_cred =3D ovl_override_creds(file_inode(in)->i_sb); > > + ret =3D real.file->f_op->splice_read(real.file, ppos, pipe, le= n, flags); > = > I don't think you replied to my suggestion of using a helper here. > E.g. it could be as simple as exporting do_splice_to(), or renaming it > to vfs_splice_read() to be more readable. It would remove the > boilerplate and be more robust if any changes are done to the splice > reading code. Using do_splice_to() as a helper is probably a good idea, though both Will= y and Christoph seem to dislike it. The pipe occupancy check has already been done, so I'm not sure if it shou= ld be repeated - though it probably wouldn't hurt. David