[PATCH v13 068/137] mm/writeback: Add folio_mark_dirty()

Matthew Wilcox (Oracle)
2021-07-12T03:44:16Z

Reimplement set_page_dirty() as a wrapper around folio_mark_dirty().
There is no change to filesystems as they were already being called
with the compound_head of the page being marked dirty. We avoid
several calls to compound_head(), both statically (through
using folio_dirty() instead of PageDirty() and dynamically by
calling folio_mapping() instead of page_mapping().

Also return bool instead of int to show the range of values actually
returned, and add kernel-doc.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
include/linux/mm.h | 3 ++-
mm/folio-compat.c | 6 ++++++
mm/page-writeback.c | 35 +++++++++++++++++++----------------
3 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 12e78faa3519..069378a073a9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2004,7 +2004,8 @@ int redirty_page_for_writepage(struct writeback_control *wbc,
struct page *page);
void account_page_cleaned(struct page *page, struct address_space *mapping,
struct bdi_writeback *wb);
-int set_page_dirty(struct page *page);
+bool folio_mark_dirty(struct folio *folio);
+bool set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
void __cancel_dirty_page(struct page *page);
static inline void cancel_dirty_page(struct page *page)
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 10ce5582d869..2c2b3917b5dc 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -77,3 +77,9 @@ bool set_page_writeback(struct page *page)
return folio_start_writeback(page_folio(page));
}
EXPORT_SYMBOL(set_page_writeback);
+
+bool set_page_dirty(struct page *page)
+{
+ return folio_mark_dirty(page_folio(page));
+}
+EXPORT_SYMBOL(set_page_dirty);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2b908c1913ca..8dca0f3e46af 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2564,18 +2564,21 @@ int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page)
}
EXPORT_SYMBOL(redirty_page_for_writepage);

-/*
- * Dirty a page.
+/**
+ * folio_mark_dirty - Mark a folio as being modified.
+ * @folio: The folio.
+ *
+ * For folios with a mapping this should be done under the page lock
+ * for the benefit of asynchronous memory errors who prefer a consistent
+ * dirty state. This rule can be broken in some special cases,
+ * but should be better not to.
*
- * For pages with a mapping this should be done under the page lock for the
- * benefit of asynchronous memory errors who prefer a consistent dirty state.
- * This rule can be broken in some special cases, but should be better not to.
+ * Return: True if the folio was newly dirtied, false if it was already dirty.
*/
-int set_page_dirty(struct page *page)
+bool folio_mark_dirty(struct folio *folio)
{
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping = folio_mapping(folio);

- page = compound_head(page);
if (likely(mapping)) {
/*
* readahead/lru_deactivate_page could remain
@@ -2587,17 +2590,17 @@ int set_page_dirty(struct page *page)
* it will confuse readahead and make it restart the size rampup
* process. But it's a trivial problem.
*/
- if (PageReclaim(page))
- ClearPageReclaim(page);
- return mapping->a_ops->set_page_dirty(page);
+ if (folio_reclaim(folio))
+ folio_clear_reclaim_flag(folio);
+ return mapping->a_ops->set_page_dirty(&folio->page);
}
- if (!PageDirty(page)) {
- if (!TestSetPageDirty(page))
- return 1;
+ if (!folio_dirty(folio)) {
+ if (!folio_test_set_dirty_flag(folio))
+ return true;
}
- return 0;
+ return false;
}
-EXPORT_SYMBOL(set_page_dirty);
+EXPORT_SYMBOL(folio_mark_dirty);

/*
* set_page_dirty() is racy if the caller has no reference against
--
2.30.2