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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20250811-iot_iter_folio-v1-1-d9c223adf93c@codewreck.org> <20250811-iot_iter_folio-v1-0-d9c223adf93c@codewreck.org> <385673.1754923063@warthog.procyon.org.uk> To: asmadeus@codewreck.org Cc: dhowells@redhat.com, "Matthew Wilcox (Oracle)" , Christian Brauner , Alexander Viro , Andrew Morton , Maximilian Bosch , Ryan Lahfa , Christian Theune , Arnout Engelen , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/2] iov_iter: iterate_folioq: fix handling of offset >= folio size Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <650268.1754991257.1@warthog.procyon.org.uk> Date: Tue, 12 Aug 2025 10:34:17 +0100 Message-ID: <650269.1754991257@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 asmadeus@codewreck.org wrote: > There should be a `if (slot == folioq_nr_slots(folioq)) break` check > somewhere as well? Or is the iov_iter guaranteed to always 1/ have some > data and 2/ either be big enough or have remaining data in a step? We should handle both cases. I think the other iteration functions will. iov_iter_extractg_folioq_pages(), for example, wraps it in a conditional: if (offset < fsize) { part = umin(part, umin(maxsize - extracted, fsize - offset)); i->count -= part; i->iov_offset += part; extracted += part; p[nr++] = folio_page(folio, offset / PAGE_SIZE); } David