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[209.85.208.50]) by smtp.gmail.com with ESMTPSA id q17-20020a50c351000000b004af640933desm3276495edb.78.2023.02.24.08.22.20 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Feb 2023 08:22:21 -0800 (PST) Received: by mail-ed1-f50.google.com with SMTP id d30so15614515eda.4 for ; Fri, 24 Feb 2023 08:22:20 -0800 (PST) X-Received: by 2002:a50:d619:0:b0:4ab:3a49:68b9 with SMTP id x25-20020a50d619000000b004ab3a4968b9mr7634213edi.5.1677255740399; Fri, 24 Feb 2023 08:22:20 -0800 (PST) MIME-Version: 1.0 References: <2134430.1677240738@warthog.procyon.org.uk> <2009825.1677229488@warthog.procyon.org.uk> <20230220135225.91b0f28344c01d5306c31230@linux-foundation.org> <2213409.1677249075@warthog.procyon.org.uk> <2244151.1677251586@warthog.procyon.org.uk> In-Reply-To: <2244151.1677251586@warthog.procyon.org.uk> From: Linus Torvalds Date: Fri, 24 Feb 2023 08:22:03 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC][PATCH] cifs: Improve use of filemap_get_folios_tag() To: David Howells Cc: Steve French , Vishal Moola , Andrew Morton , Jan Kara , Paulo Alcantara , Matthew Wilcox , Huang Ying , Baolin Wang , Xin Hao , linux-mm@kvack.org, mm-commits@vger.kernel.org, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B21131C0027 X-Stat-Signature: 13d93b4dieyiwjg83t3pwnyn9xub433k X-HE-Tag: 1677255743-178940 X-HE-Meta: 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 VQsSEoIm 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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, Feb 24, 2023 at 7:13 AM David Howells wrote: > > The inefficiency derived from filemap_get_folios_tag() get a batch of > contiguous folios in Vishal's change to afs that got copied into cifs can > be reduced by skipping over those folios that have been passed by the start > position rather than going through the process of locking, checking and > trying to write them. This patch just makes me go "Ugh". There's something wrong with this code for it to need these games. That just makes me convinced that your other patch that just gets rid of the batching entirely is the right one. Of course, I'd be even happier if Willy is right and the code could use the generic write_cache_pages() and avoid all of these things entirely. I'm not clear on why cifs and afs are being so different in the first place, and some of the differences are just odd (like that skip count). Linus