[v5,11/39] fs: Support THPs in zero_user_segments
diff mbox series

Message ID 20200529025824.32296-12-willy@infradead.org
State New
Headers show
Series
  • Large pages in the page cache
Related show

Commit Message

Matthew Wilcox May 29, 2020, 2:57 a.m. UTC
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

We can only kmap() one subpage of a THP at a time, so loop over all
relevant subpages, skipping ones which don't need to be zeroed.  This is
too large to inline when THPs are enabled and we actually need highmem,
so put it in highmem.c.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/highmem.h | 15 +++++++---
 mm/highmem.c            | 62 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 71 insertions(+), 6 deletions(-)

Patch
diff mbox series

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index ea5cdbd8c2c3..74614903619d 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -215,13 +215,18 @@  static inline void clear_highpage(struct page *page)
 	kunmap_atomic(kaddr);
 }
 
+#if defined(CONFIG_HIGHMEM) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
+		unsigned start2, unsigned end2);
+#else /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
 static inline void zero_user_segments(struct page *page,
-	unsigned start1, unsigned end1,
-	unsigned start2, unsigned end2)
+		unsigned start1, unsigned end1,
+		unsigned start2, unsigned end2)
 {
+	unsigned long i;
 	void *kaddr = kmap_atomic(page);
 
-	BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
+	BUG_ON(end1 > thp_size(page) || end2 > thp_size(page));
 
 	if (end1 > start1)
 		memset(kaddr + start1, 0, end1 - start1);
@@ -230,8 +235,10 @@  static inline void zero_user_segments(struct page *page,
 		memset(kaddr + start2, 0, end2 - start2);
 
 	kunmap_atomic(kaddr);
-	flush_dcache_page(page);
+	for (i = 0; i < hpage_nr_pages(page); i++)
+		flush_dcache_page(page + i);
 }
+#endif /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
 
 static inline void zero_user_segment(struct page *page,
 	unsigned start, unsigned end)
diff --git a/mm/highmem.c b/mm/highmem.c
index 64d8dea47dd1..3a85c66ef532 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -367,9 +367,67 @@  void kunmap_high(struct page *page)
 	if (need_wakeup)
 		wake_up(pkmap_map_wait);
 }
-
 EXPORT_SYMBOL(kunmap_high);
-#endif
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
+		unsigned start2, unsigned end2)
+{
+	unsigned int i;
+
+	BUG_ON(end1 > thp_size(page) || end2 > thp_size(page));
+
+	for (i = 0; i < hpage_nr_pages(page); i++) {
+		void *kaddr;
+		unsigned this_end;
+
+		if (end1 == 0 && start2 >= PAGE_SIZE) {
+			start2 -= PAGE_SIZE;
+			end2 -= PAGE_SIZE;
+			continue;
+		}
+
+		if (start1 >= PAGE_SIZE) {
+			start1 -= PAGE_SIZE;
+			end1 -= PAGE_SIZE;
+			if (start2) {
+				start2 -= PAGE_SIZE;
+				end2 -= PAGE_SIZE;
+			}
+			continue;
+		}
+
+		kaddr = kmap_atomic(page + i);
+
+		this_end = min_t(unsigned, end1, PAGE_SIZE);
+		if (end1 > start1)
+			memset(kaddr + start1, 0, this_end - start1);
+		end1 -= this_end;
+		start1 = 0;
+
+		if (start2 >= PAGE_SIZE) {
+			start2 -= PAGE_SIZE;
+			end2 -= PAGE_SIZE;
+		} else {
+			this_end = min_t(unsigned, end2, PAGE_SIZE);
+			if (end2 > start2)
+				memset(kaddr + start2, 0, this_end - start2);
+			end2 -= this_end;
+			start2 = 0;
+		}
+
+		kunmap_atomic(kaddr);
+		flush_dcache_page(page + i);
+
+		if (!end1 && !end2)
+			break;
+	}
+
+	BUG_ON((start1 | start2 | end1 | end2) != 0);
+}
+EXPORT_SYMBOL(zero_user_segments);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif /* CONFIG_HIGHMEM */
 
 #if defined(HASHED_PAGE_VIRTUAL)