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[209.85.167.47]) by smtp.gmail.com with ESMTPSA id d25sm1540190ljj.51.2019.12.11.09.20.08 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Dec 2019 09:20:08 -0800 (PST) Received: by mail-lf1-f47.google.com with SMTP id b15so17310705lfc.4 for ; Wed, 11 Dec 2019 09:20:08 -0800 (PST) X-Received: by 2002:ac2:4946:: with SMTP id o6mr2995836lfi.170.1576084808314; Wed, 11 Dec 2019 09:20:08 -0800 (PST) MIME-Version: 1.0 References: <20191211152943.2933-1-axboe@kernel.dk> <20191211152943.2933-5-axboe@kernel.dk> In-Reply-To: <20191211152943.2933-5-axboe@kernel.dk> From: Linus Torvalds Date: Wed, 11 Dec 2019 09:19:52 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 4/5] iomap: pass in the write_begin/write_end flags to iomap_actor To: Jens Axboe Cc: Linux-MM , linux-fsdevel , linux-block , Matthew Wilcox , Chris Mason , Dave Chinner Content-Type: text/plain; charset="UTF-8" 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 Wed, Dec 11, 2019 at 7:29 AM Jens Axboe wrote: > > This is in preparation for passing in a flag to the iomap_actor, which > currently doesn't support that. This really looks like we should use a struct for passing the arguments, no? Now on 64-bit, you the iomap_actor() has seven arguments, which already means that it's passing some of them on the stack on most architectures. On 32-bit, it's even worse, because two of the arguments are "loff_t", which means that they are 2 words each, so you have 9 words of arguments. I don't know a single architecture that does register passing for things like that. If you were to change the calling convention _first_ to do a "struct iomap_actor" or whatever, then adding the "flags" field would be a trivial addition. Linus