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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rKbwd-009yqz-4e; Tue, 02 Jan 2024 10:24:23 +0000 Date: Tue, 2 Jan 2024 10:24:23 +0000 From: Matthew Wilcox To: David Howells Cc: Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: bio_vec, bv_page and folios Message-ID: References: <3490948.1704185806@warthog.procyon.org.uk> <5779.1704189838@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5779.1704189838@warthog.procyon.org.uk> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 9DB2318001A X-Stat-Signature: o7dq5h6g8ooqxg8cg8cbsfhbcrknbwmm X-Rspam-User: X-HE-Tag: 1704191069-826386 X-HE-Meta: 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 jPeyaLhb xsrrc7+pVB9UvJkJilS8AExcrkuwsmQnq67hjRoNOKqtRrTlvW8RFeBw/vzYm/f8eTohv7wjyVf/JLYuGQMQr0dx8cXS6mp+0qPNr3hocQFJr6XlXhnAbY+dGJxUau0dFnL65y2gJ3xmfycuQjQA/Tc+Xgre04b7pSD0RDeQakOkGPrNO9ceEKm4sfH/iTDgC+q5PKZBMsTAlUUAUVXqYzhyUm/RNuw/yf0g1wrWSWpN+4pM= 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: List-Subscribe: List-Unsubscribe: On Tue, Jan 02, 2024 at 10:03:58AM +0000, David Howells wrote: > Matthew Wilcox wrote: > > > On Tue, Jan 02, 2024 at 08:56:46AM +0000, David Howells wrote: > > > Hi Christoph, Willy, > > > > > > Will bv_page in struct bio_vec ever become a folio pointer rather than I page > > > pointer? I'm guessing not as it still presumably needs to be able to point to > > > non-folio pages. > > > > My plan for bio_vec is that it becomes phyr -- a physical address + > > length. No more page or folio reference. > > Interesting... What does that mean for those places that currently use > bv_page as a place to stash a pointer to the page and use it to clean up the > page later? I don't intend to get rid of bio_for_each_folio_all() or bio_add_page() for example. It's just a phys_to_page() away. The advantage is that we wouldn't need a struct page to do I/O to a physical address.