[PATCHv3 20/41] mm: make write_cache_pages() work on huge pages

[Kirill A. Shutemov]

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

Signed-off-by: Kirill A. Shutemov 
---
 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 ef815b9cd426..44e55d1c8e41 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1054,6 +1054,7 @@ struct address_space *page_file_mapping(struct page *page)
  */
 static inline pgoff_t page_index(struct page *page)
 {
+   page = compound_head(page);
if (unlikely(PageSwapCache(page)))
return page_private(page);
return page->index;
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a84f11a672f0..4d6e9aec2d1f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -518,6 +518,7 @@ 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 f4cd7d8005c9..6390c9488e29 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2242,7 +2242,7 @@ retry:
 * 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.
@@ -2251,7 +2251,12 @@ retry:
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);
 
@@ -2263,7 +2268,7 @@ retry:
 * 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;
@@ -2301,7 +2306,8 @@ continue_unlock:
 * 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;
}
@@ -2313,7 +2319,8 @@ continue_unlock:
 * 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;
-- 
2.9.3

[PATCHv3 20/41] mm: make write_cache_pages() work on huge pages

[Kirill A. Shutemov]

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

Signed-off-by: Kirill A. Shutemov 
---
 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 ef815b9cd426..44e55d1c8e41 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1054,6 +1054,7 @@ struct address_space *page_file_mapping(struct page *page)
  */
 static inline pgoff_t page_index(struct page *page)
 {
+   page = compound_head(page);
if (unlikely(PageSwapCache(page)))
return page_private(page);
return page->index;
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a84f11a672f0..4d6e9aec2d1f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -518,6 +518,7 @@ 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 f4cd7d8005c9..6390c9488e29 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2242,7 +2242,7 @@ retry:
 * 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.
@@ -2251,7 +2251,12 @@ retry:
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);
 
@@ -2263,7 +2268,7 @@ retry:
 * 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;
@@ -2301,7 +2306,8 @@ continue_unlock:
 * 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;
}
@@ -2313,7 +2319,8 @@ continue_unlock:
 * 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;
-- 
2.9.3