[PATCH v14 071/138] mm/writeback: Add filemap_dirty_folio()

Matthew Wilcox (Oracle)
2021-07-15T04:34:47Z

Reimplement __set_page_dirty_nobuffers() as a wrapper around
filemap_dirty_folio().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
include/linux/writeback.h | 1 +
mm/folio-compat.c | 6 ++++
mm/page-writeback.c | 60 ++++++++++++++++++++-------------------
3 files changed, 38 insertions(+), 29 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 667e86cfbdcf..eda9cc778ef6 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -398,6 +398,7 @@ void writeback_set_ratelimit(void);
void tag_pages_for_writeback(struct address_space *mapping,
pgoff_t start, pgoff_t end);

+bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio);
void account_page_redirty(struct page *page);

void sb_mark_inode_writeback(struct inode *inode);
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 2c2b3917b5dc..dad962b920e5 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -83,3 +83,9 @@ bool set_page_dirty(struct page *page)
return folio_mark_dirty(page_folio(page));
}
EXPORT_SYMBOL(set_page_dirty);
+
+int __set_page_dirty_nobuffers(struct page *page)
+{
+ return filemap_dirty_folio(page_mapping(page), page_folio(page));
+}
+EXPORT_SYMBOL(__set_page_dirty_nobuffers);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2dc410b110ff..bd97c461d499 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2488,41 +2488,43 @@ void __folio_mark_dirty(struct folio *folio, struct address_space *mapping,
xa_unlock_irqrestore(&mapping->i_pages, flags);
}

-/*
- * For address_spaces which do not use buffers. Just tag the page as dirty in
- * the xarray.
- *
- * This is also used when a single buffer is being dirtied: we want to set the
- * page dirty in that case, but not all the buffers. This is a "bottom-up"
- * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying.
- *
- * The caller must ensure this doesn't race with truncation. Most will simply
- * hold the page lock, but e.g. zap_pte_range() calls with the page mapped and
- * the pte lock held, which also locks out truncation.
+/**
+ * filemap_dirty_folio - Mark a folio dirty for filesystems which do not use buffer_heads.
+ * @mapping: Address space this folio belongs to.
+ * @folio: Folio to be marked as dirty.
+ *
+ * Filesystems which do not use buffer heads should call this function
+ * from their set_page_dirty address space operation. It ignores the
+ * contents of folio_get_private(), so if the filesystem marks individual
+ * blocks as dirty, the filesystem should handle that itself.
+ *
+ * This is also sometimes used by filesystems which use buffer_heads when
+ * a single buffer is being dirtied: we want to set the folio dirty in
+ * that case, but not all the buffers. This is a "bottom-up" dirtying,
+ * whereas __set_page_dirty_buffers() is a "top-down" dirtying.
+ *
+ * The caller must ensure this doesn't race with truncation. Most will
+ * simply hold the folio lock, but e.g. zap_pte_range() calls with the
+ * folio mapped and the pte lock held, which also locks out truncation.
*/
-int __set_page_dirty_nobuffers(struct page *page)
+bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio)
{
- lock_page_memcg(page);
- if (!TestSetPageDirty(page)) {
- struct address_space *mapping = page_mapping(page);
+ folio_memcg_lock(folio);
+ if (folio_test_set_dirty(folio)) {
+ folio_memcg_unlock(folio);
+ return false;
+ }

- if (!mapping) {
- unlock_page_memcg(page);
- return 1;
- }
- __set_page_dirty(page, mapping, !PagePrivate(page));
- unlock_page_memcg(page);
+ __folio_mark_dirty(folio, mapping, !folio_test_private(folio));
+ folio_memcg_unlock(folio);

- if (mapping->host) {
- /* !PageAnon && !swapper_space */
- __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
- }
- return 1;
+ if (mapping->host) {
+ /* !PageAnon && !swapper_space */
+ __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
}
- unlock_page_memcg(page);
- return 0;
+ return true;
}
-EXPORT_SYMBOL(__set_page_dirty_nobuffers);
+EXPORT_SYMBOL(filemap_dirty_folio);

/*
* Call this whenever redirtying a page, to de-account the dirty counters
--
2.30.2