[PATCH v2 13/25] fs: Add zero_user_large

Matthew Wilcox
2020-02-12T04:19:59Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

We can't kmap() a THP, so add a wrapper around zero_user() for large
pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/highmem.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index ea5cdbd8c2c3..4465b8784353 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -245,6 +245,28 @@ static inline void zero_user(struct page *page,
zero_user_segments(page, start, start + size, 0, 0);
}

+static inline void zero_user_large(struct page *page,
+ unsigned start, unsigned size)
+{
+ unsigned int i;
+
+ for (i = 0; i < thp_order(page); i++) {
+ if (start > PAGE_SIZE) {
+ start -= PAGE_SIZE;
+ } else {
+ unsigned this_size = size;
+
+ if (size > (PAGE_SIZE - start))
+ this_size = PAGE_SIZE - start;
+ zero_user(page + i, start, this_size);
+ start = 0;
+ size -= this_size;
+ if (!size)
+ break;
+ }
+ }
+}
+
#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE

static inline void copy_user_highpage(struct page *to, struct page *from,
--
2.25.0