[PATCH RFC 18/35] io_uring/zcrx: remove "struct io_copy_cache" and one nth_page() usage
From: David Hildenbrand <hidden>
Date: 2025-08-21 20:08:00
Also in:
dri-devel, intel-gfx, io-uring, kvm, linux-arm-kernel, linux-crypto, linux-ide, linux-iommu, linux-kselftest, linux-mips, linux-mm, linux-mmc, linux-riscv, linux-s390, linux-scsi, lkml, virtualization
Subsystem:
io_uring, io_uring zcrx, the rest · Maintainers:
Jens Axboe, Pavel Begunkov, Linus Torvalds
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 <axboe@kernel.dk> Signed-off-by: David Hildenbrand <redacted> --- 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);
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2.50.1