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[2003:cb:c749:cb00:fc9f:d303:d4cc:9f26]) by smtp.gmail.com with ESMTPSA id p12-20020adfcc8c000000b0030adfa48e1esm5812964wrj.29.2023.05.31.00.42.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 31 May 2023 00:42:28 -0700 (PDT) Message-ID: Date: Wed, 31 May 2023 09:42:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Content-Language: en-US To: David Howells , Christoph Hellwig , Lorenzo Stoakes Cc: Jens Axboe , Al Viro , Matthew Wilcox , Jan Kara , Jeff Layton , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , Christian Brauner , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , John Hubbard References: <20230526214142.958751-1-dhowells@redhat.com> <20230526214142.958751-3-dhowells@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v4 2/3] mm: Provide a function to get an additional pin on a page In-Reply-To: <20230526214142.958751-3-dhowells@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 26.05.23 23:41, David Howells wrote: > Provide a function to get an additional pin on a page that we already have > a pin on. This will be used in fs/direct-io.c when dispatching multiple > bios to a page we've extracted from a user-backed iter rather than redoing > the extraction. > I guess this function is only used for "replicating" an existing pin, and not changing the semantics of an existing pin: something that was pinned !FOLL_LONGTERM cannot suddenly become effectively pinned FOLL_LONGTERM. Out of curiosity, could we end up passing in an anonymous page, or is this almost exclusively for pagecache+zero pages? (I rememebr John H. had a similar patch where he said it would not apply to anon pages) > Signed-off-by: David Howells > cc: Christoph Hellwig > cc: David Hildenbrand > cc: Lorenzo Stoakes > cc: Andrew Morton > cc: Jens Axboe > cc: Al Viro > cc: Matthew Wilcox > cc: Jan Kara > cc: Jeff Layton > cc: Jason Gunthorpe > cc: Logan Gunthorpe > cc: Hillf Danton > cc: Christian Brauner > cc: Linus Torvalds > cc: linux-fsdevel@vger.kernel.org > cc: linux-block@vger.kernel.org > cc: linux-kernel@vger.kernel.org > cc: linux-mm@kvack.org > --- Acked-by: David Hildenbrand -- Thanks, David / dhildenb