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[209.85.208.54]) by smtp.gmail.com with ESMTPSA id lo18-20020a170906fa1200b0099bd1a78ef5sm3054315ejb.74.2023.09.22.11.51.36 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Sep 2023 11:51:36 -0700 (PDT) Received: by mail-ed1-f54.google.com with SMTP id 4fb4d7f45d1cf-52889bc61b6so3068706a12.0 for ; Fri, 22 Sep 2023 11:51:36 -0700 (PDT) X-Received: by 2002:aa7:c98b:0:b0:533:310b:a8aa with SMTP id c11-20020aa7c98b000000b00533310ba8aamr309019edt.13.1695408696292; Fri, 22 Sep 2023 11:51:36 -0700 (PDT) MIME-Version: 1.0 References: <20230922120227.1173720-1-dhowells@redhat.com> <20230922120227.1173720-10-dhowells@redhat.com> In-Reply-To: <20230922120227.1173720-10-dhowells@redhat.com> From: Linus Torvalds Date: Fri, 22 Sep 2023 11:51:19 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 09/13] iov_iter: Add a kernel-type iterator-only iteration function To: David Howells Cc: Jens Axboe , Al Viro , Christoph Hellwig , Christian Brauner , David Laight , Matthew Wilcox , Jeff Layton , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: E49B218000E X-Rspam-User: X-Stat-Signature: c1qgmje557cnrjwe3smfj6qbdpfjdhxb X-Rspamd-Server: rspam01 X-HE-Tag: 1695408701-562694 X-HE-Meta: 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 QnfxFNhM 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 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: On Fri, 22 Sept 2023 at 05:03, David Howells wrote: > > Add an iteration function that can only iterate over kernel internal-type > iterators (ie. BVEC, KVEC, XARRAY) and not user-backed iterators (ie. UBUF > and IOVEC). This allows for smaller iterators to be built when it is known > the caller won't have a user-backed iterator. This one is pretty ugly, and has no actual users. Without even explaining why we'd care about this abomination, NAK. If we actyually have some static knowledge of "this will only use iterators X/Y/Z", then we should probably pass that in as a constant bitmask to the thing, instead of this kind of "kernel only" special case. But even then, we'd want to have actual explicit use-cases, not a hypothetical "if you have this situation here's this function". Linus