From 908a1ad89466c1febf20bfe0037b84fc66f8a3f8 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Tue, 6 Jun 2023 16:43:32 -0400 Subject: iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic() copy_page_from_iter_atomic() already handles !highmem compound pages correctly, but if we are passed a highmem compound page, each base page needs to be mapped & unmapped individually. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: Kent Overstreet Reviewed-by: Darrick J. Wong Tested-by: Kent Overstreet --- lib/iov_iter.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) (limited to 'lib/iov_iter.c') diff --git a/lib/iov_iter.c b/lib/iov_iter.c index db58af778291..eb3dffb24aae 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -566,24 +566,37 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i) } EXPORT_SYMBOL(iov_iter_zero); -size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes, - struct iov_iter *i) +size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, + size_t bytes, struct iov_iter *i) { - char *p; + size_t n, copied = 0; if (!page_copy_sane(page, offset, bytes)) return 0; if (WARN_ON_ONCE(!i->data_source)) return 0; - p = kmap_atomic(page) + offset; - iterate_and_advance(i, bytes, base, len, off, - copyin(p + off, base, len), - memcpy_from_iter(i, p + off, base, len) - ) - kunmap_atomic(p); + do { + char *p; - return bytes; + n = bytes - copied; + if (PageHighMem(page)) { + page += offset / PAGE_SIZE; + offset %= PAGE_SIZE; + n = min_t(size_t, n, PAGE_SIZE - offset); + } + + p = kmap_atomic(page) + offset; + iterate_and_advance(i, n, base, len, off, + copyin(p + off, base, len), + memcpy_from_iter(i, p + off, base, len) + ) + kunmap_atomic(p); + copied += n; + offset += n; + } while (PageHighMem(page) && copied != bytes && n > 0); + + return copied; } EXPORT_SYMBOL(copy_page_from_iter_atomic); -- cgit v1.2.3