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Thu, 08 Apr 2021 02:01:58 -0700 (PDT) Received: from [192.168.1.149] ([80.208.71.248]) by smtp.gmail.com with ESMTPSA id s6sm10262058ejv.11.2021.04.08.02.01.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Apr 2021 02:01:58 -0700 (PDT) Subject: Re: [PATCH v6 01/27] mm: Introduce struct folio To: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, linux-afs@lists.infradead.org References: <20210331184728.1188084-1-willy@infradead.org> <20210331184728.1188084-2-willy@infradead.org> From: Rasmus Villemoes Message-ID: Date: Thu, 8 Apr 2021 11:01:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210331184728.1188084-2-willy@infradead.org> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Stat-Signature: ecgmwsk589fwi31ww6k5nzrmnx396mtq X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2C598C0007D9 Received-SPF: none (rasmusvillemoes.dk>: No applicable sender policy available) receiver=imf22; identity=mailfrom; envelope-from=""; helo=mail-ej1-f53.google.com; client-ip=209.85.218.53 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617872518-696540 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 31/03/2021 20.47, Matthew Wilcox (Oracle) wrote: > +static inline void folio_build_bug(void) > +{ > +#define FOLIO_MATCH(pg, fl) \ > +BUILD_BUG_ON(offsetof(struct page, pg) != offsetof(struct folio, fl)); > + > + FOLIO_MATCH(flags, flags); > + FOLIO_MATCH(lru, lru); > + FOLIO_MATCH(mapping, mapping); > + FOLIO_MATCH(index, index); > + FOLIO_MATCH(private, private); > + FOLIO_MATCH(_mapcount, _mapcount); > + FOLIO_MATCH(_refcount, _refcount); > +#ifdef CONFIG_MEMCG > + FOLIO_MATCH(memcg_data, memcg_data); > +#endif > +#undef FOLIO_MATCH > + BUILD_BUG_ON(sizeof(struct page) != sizeof(struct folio)); > +} > + Perhaps do this next to the definition of struct folio instead of hiding it in some arbitrary TU - hint, we have static_assert() that doesn't need to be in function context. And consider amending FOLIO_MATCH by a static_assert(__same_type(typeof_member(...), typeof_member(...))). Rasmus