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io_uring/zcrx: remove nth_page() usage within folio 

Within a folio/compound page, nth_page() is no longer required.  Given
that we call folio_test_partial_kmap()+kmap_local_page(), the code would
already be problematic if the pages would span multiple folios.

So let's just assume that all src pages belong to a single folio/compound
page and can be iterated ordinarily.  The dst page is currently always a
single page, so we're not actually iterating anything.

Link: https://lkml.kernel.org/r/20250901150359.867252-21-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
pull/1354/merge
David Hildenbrand 2025-09-01 17:03:41 +02:00 committed by Andrew Morton
parent e3c05b6e37
commit d99c57546d
1 changed files with 2 additions and 2 deletions
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4
io_uring/zcrx.c
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@ -975,9 +975,9 @@ static ssize_t io_copy_page(struct io_copy_cache *cc, struct page *src_page,
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_page += dst_offset / PAGE_SIZE;
dst_offset = offset_in_page(dst_offset);
src_page = nth_page(src_page, src_offset / PAGE_SIZE);
src_page += src_offset / PAGE_SIZE;
src_offset = offset_in_page(src_offset);
n = min(PAGE_SIZE - src_offset, PAGE_SIZE - dst_offset);
n = min(n, len);