[PATCH v6 22/27] mm/filemap: Add end_folio_writeback

Matthew Wilcox (Oracle)
2021-03-31T18:56:45Z

Add an end_page_writeback() wrapper function for users that are not yet
converted to folios.

end_folio_writeback() is less than half the size of end_page_writeback()
at just 105 bytes compared to 213 bytes, due to removing all the
compound_head() calls. The 30 byte wrapper function makes this a net
saving of 70 bytes.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/pagemap.h | 3 ++-
mm/filemap.c | 38 +++++++++++++++++++-------------------
mm/folio-compat.c | 6 ++++++
3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a7bbc34d92cb..36c31cfa3e64 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -830,7 +830,8 @@ static inline int wait_on_page_locked_killable(struct page *page)
int put_and_wait_on_page_locked(struct page *page, int state);
void wait_on_page_writeback(struct page *page);
int wait_on_page_writeback_killable(struct page *page);
-extern void end_page_writeback(struct page *page);
+void end_page_writeback(struct page *page);
+void end_folio_writeback(struct folio *folio);
void wait_for_stable_page(struct page *page);

void page_endio(struct page *page, bool is_write, int err);
diff --git a/mm/filemap.c b/mm/filemap.c
index 21607db04835..4591974f2c28 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1175,11 +1175,11 @@ static void wake_up_page_bit(struct page *page, int bit_nr)
spin_unlock_irqrestore(&q->lock, flags);
}

-static void wake_up_page(struct page *page, int bit)
+static void wake_up_folio(struct folio *folio, int bit)
{
- if (!PageWaiters(page))
+ if (!FolioWaiters(folio))
return;
- wake_up_page_bit(page, bit);
+ wake_up_page_bit(&folio->page, bit);
}

/*
@@ -1473,38 +1473,38 @@ void unlock_page_private_2(struct page *page)
EXPORT_SYMBOL(unlock_page_private_2);

/**
- * end_page_writeback - end writeback against a page
- * @page: the page
+ * end_folio_writeback - End writeback against a folio.
+ * @folio: The folio.
*/
-void end_page_writeback(struct page *page)
+void end_folio_writeback(struct folio *folio)
{
/*
* TestClearPageReclaim could be used here but it is an atomic
* operation and overkill in this particular case. Failing to
- * shuffle a page marked for immediate reclaim is too mild to
+ * shuffle a folio marked for immediate reclaim is too mild to
* justify taking an atomic operation penalty at the end of
- * ever page writeback.
+ * every folio writeback.
*/
- if (PageReclaim(page)) {
- ClearPageReclaim(page);
- rotate_reclaimable_page(page);
+ if (FolioReclaim(folio)) {
+ ClearFolioReclaim(folio);
+ rotate_reclaimable_page(&folio->page);
}

/*
- * Writeback does not hold a page reference of its own, relying
+ * Writeback does not hold a folio reference of its own, relying
* on truncation to wait for the clearing of PG_writeback.
- * But here we must make sure that the page is not freed and
- * reused before the wake_up_page().
+ * But here we must make sure that the folio is not freed and
+ * reused before the wake_up_folio().
*/
- get_page(page);
- if (!test_clear_page_writeback(page))
+ get_folio(folio);
+ if (!test_clear_page_writeback(&folio->page))
BUG();

smp_mb__after_atomic();
- wake_up_page(page, PG_writeback);
- put_page(page);
+ wake_up_folio(folio, PG_writeback);
+ put_folio(folio);
}
-EXPORT_SYMBOL(end_page_writeback);
+EXPORT_SYMBOL(end_folio_writeback);

/*
* After completing I/O on a page, call this routine to update the page
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 02798abf19a1..d1a1dfe52589 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -17,3 +17,9 @@ void unlock_page(struct page *page)
return unlock_folio(page_folio(page));
}
EXPORT_SYMBOL(unlock_page);
+
+void end_page_writeback(struct page *page)
+{
+ return end_folio_writeback(page_folio(page));
+}
+EXPORT_SYMBOL(end_page_writeback);
--
2.30.2