[PATCHv5 13/36] mm: make write_cache_pages() work on huge pages

Kirill A. Shutemov
2016-11-29T11:22:41Z

We writeback whole huge page a time. Let's adjust iteration this way.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/mm.h | 1 +
include/linux/pagemap.h | 1 +
mm/page-writeback.c | 17 ++++++++++++-----
3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4424784ac374..582844ca0b23 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1045,6 +1045,7 @@ extern pgoff_t __page_file_index(struct page *page);
*/
static inline pgoff_t page_index(struct page *page)
{
+ page = compound_head(page);
if (unlikely(PageSwapCache(page)))
return __page_file_index(page);
return page->index;
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e530e7b3b6b2..faa3fa173939 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -546,6 +546,7 @@ static inline void wait_on_page_locked(struct page *page)
*/
static inline void wait_on_page_writeback(struct page *page)
{
+ page = compound_head(page);
if (PageWriteback(page))
wait_on_page_bit(page, PG_writeback);
}
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 290e8b7d3181..47d5b12c460e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2209,7 +2209,7 @@ int write_cache_pages(struct address_space *mapping,
* mapping. However, page->index will not change
* because we have a reference on the page.
*/
- if (page->index > end) {
+ if (page_to_pgoff(page) > end) {
/*
* can't be range_cyclic (1st pass) because
* end == -1 in that case.
@@ -2218,7 +2218,12 @@ int write_cache_pages(struct address_space *mapping,
break;
}

- done_index = page->index;
+ done_index = page_to_pgoff(page);
+ if (PageTransCompound(page)) {
+ index = round_up(index + 1, HPAGE_PMD_NR);
+ i += HPAGE_PMD_NR -
+ done_index % HPAGE_PMD_NR - 1;
+ }

lock_page(page);

@@ -2230,7 +2235,7 @@ int write_cache_pages(struct address_space *mapping,
* even if there is now a new, dirty page at the same
* pagecache address.
*/
- if (unlikely(page->mapping != mapping)) {
+ if (unlikely(page_mapping(page) != mapping)) {
continue_unlock:
unlock_page(page);
continue;
@@ -2268,7 +2273,8 @@ int write_cache_pages(struct address_space *mapping,
* not be suitable for data integrity
* writeout).
*/
- done_index = page->index + 1;
+ done_index = compound_head(page)->index
+ + hpage_nr_pages(page);
done = 1;
break;
}
@@ -2280,7 +2286,8 @@ int write_cache_pages(struct address_space *mapping,
* keep going until we have written all the pages
* we tagged for writeback prior to entering this loop.
*/
- if (--wbc->nr_to_write <= 0 &&
+ wbc->nr_to_write -= hpage_nr_pages(page);
+ if (wbc->nr_to_write <= 0 &&
wbc->sync_mode == WB_SYNC_NONE) {
done = 1;
break;