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[2003:d8:2f26:ba00:803:6ec5:9918:6fd]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3c4f77e968esm2903478f8f.21.2025.08.21.13.07.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Aug 2025 13:07:56 -0700 (PDT) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Jens Axboe , Alexander Potapenko , Andrew Morton , Brendan Jackman , Christoph Lameter , Dennis Zhou , Dmitry Vyukov , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, iommu@lists.linux.dev, io-uring@vger.kernel.org, Jason Gunthorpe , Johannes Weiner , John Hubbard , kasan-dev@googlegroups.com, kvm@vger.kernel.org, "Liam R. Howlett" , Linus Torvalds , linux-arm-kernel@axis.com, linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org, linux-ide@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mmc@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, Lorenzo Stoakes , Marco Elver , Marek Szyprowski , Michal Hocko , Mike Rapoport , Muchun Song , netdev@vger.kernel.org, Oscar Salvador , Peter Xu , Robin Murphy , Suren Baghdasaryan , Tejun Heo , virtualization@lists.linux.dev, Vlastimil Babka , wireguard@lists.zx2c4.com, x86@kernel.org, Zi Yan Subject: [PATCH RFC 18/35] io_uring/zcrx: remove "struct io_copy_cache" and one nth_page() usage Date: Thu, 21 Aug 2025 22:06:44 +0200 Message-ID: <20250821200701.1329277-19-david@redhat.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250821200701.1329277-1-david@redhat.com> References: <20250821200701.1329277-1-david@redhat.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit We always provide a single dst page, it's unclear why the io_copy_cache complexity is required. So let's simplify and get rid of "struct io_copy_cache", simply working on the single page. ... which immediately allows us for dropping one "nth_page" usage, because it's really just a single page. Cc: Jens Axboe Signed-off-by: David Hildenbrand --- io_uring/zcrx.c | 32 +++++++------------------------- 1 file changed, 7 insertions(+), 25 deletions(-) diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c index e5ff49f3425e0..f29b2a4867516 100644 --- a/io_uring/zcrx.c +++ b/io_uring/zcrx.c @@ -954,29 +954,18 @@ static struct net_iov *io_zcrx_alloc_fallback(struct io_zcrx_area *area) return niov; } -struct io_copy_cache { - struct page *page; - unsigned long offset; - size_t size; -}; - -static ssize_t io_copy_page(struct io_copy_cache *cc, struct page *src_page, +static ssize_t io_copy_page(struct page *dst_page, struct page *src_page, unsigned int src_offset, size_t len) { - size_t copied = 0; + size_t dst_offset = 0; - len = min(len, cc->size); + len = min(len, PAGE_SIZE); while (len) { void *src_addr, *dst_addr; - struct page *dst_page = cc->page; - unsigned dst_offset = cc->offset; size_t n = len; - if (folio_test_partial_kmap(page_folio(dst_page)) || - folio_test_partial_kmap(page_folio(src_page))) { - dst_page = nth_page(dst_page, dst_offset / PAGE_SIZE); - dst_offset = offset_in_page(dst_offset); + if (folio_test_partial_kmap(page_folio(src_page))) { src_page = nth_page(src_page, src_offset / PAGE_SIZE); src_offset = offset_in_page(src_offset); n = min(PAGE_SIZE - src_offset, PAGE_SIZE - dst_offset); @@ -991,12 +980,10 @@ static ssize_t io_copy_page(struct io_copy_cache *cc, struct page *src_page, kunmap_local(src_addr); kunmap_local(dst_addr); - cc->size -= n; - cc->offset += n; + dst_offset += n; len -= n; - copied += n; } - return copied; + return dst_offset; } static ssize_t io_zcrx_copy_chunk(struct io_kiocb *req, struct io_zcrx_ifq *ifq, @@ -1011,7 +998,6 @@ static ssize_t io_zcrx_copy_chunk(struct io_kiocb *req, struct io_zcrx_ifq *ifq, return -EFAULT; while (len) { - struct io_copy_cache cc; struct net_iov *niov; size_t n; @@ -1021,11 +1007,7 @@ static ssize_t io_zcrx_copy_chunk(struct io_kiocb *req, struct io_zcrx_ifq *ifq, break; } - cc.page = io_zcrx_iov_page(niov); - cc.offset = 0; - cc.size = PAGE_SIZE; - - n = io_copy_page(&cc, src_page, src_offset, len); + n = io_copy_page(io_zcrx_iov_page(niov), src_page, src_offset, len); if (!io_zcrx_queue_cqe(req, niov, ifq, 0, n)) { io_zcrx_return_niov(niov); -- 2.50.1