[PATCH v14 024/138] mm/filemap: Add folio_end_writeback()

Matthew Wilcox (Oracle)
2021-07-15T03:58:48Z

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

folio_end_writeback() is less than half the size of end_page_writeback()
at just 105 bytes compared to 228 bytes, due to removing all the
compound_head() calls. The 30 byte wrapper function makes this a net
saving of 93 bytes.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
---
include/linux/pagemap.h | 3 ++-
mm/filemap.c | 43 ++++++++++++++++++++---------------------
mm/folio-compat.c | 6 ++++++
3 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 626dbccbfb90..66a019178550 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -768,7 +768,8 @@ 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 folio_end_writeback(struct folio *folio);
void wait_for_stable_page(struct page *page);

void __set_page_dirty(struct page *, struct address_space *, int warn);
diff --git a/mm/filemap.c b/mm/filemap.c
index 4ce2b22b64f8..b5a0d546e436 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 folio_wake(struct folio *folio, int bit)
{
- if (!PageWaiters(page))
+ if (!folio_test_waiters(folio))
return;
- wake_up_page_bit(page, bit);
+ wake_up_page_bit(&folio->page, bit);
}

/*
@@ -1516,39 +1516,38 @@ int wait_on_page_private_2_killable(struct page *page)
EXPORT_SYMBOL(wait_on_page_private_2_killable);

/**
- * end_page_writeback - end writeback against a page
- * @page: the page
+ * folio_end_writeback - End writeback against a folio.
+ * @folio: The folio.
*/
-void end_page_writeback(struct page *page)
+void folio_end_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
- * justify taking an atomic operation penalty at the end of
- * ever page writeback.
+ * folio_test_clear_reclaim() could be used here but it is an
+ * atomic operation and overkill in this particular case. Failing
+ * to shuffle a folio marked for immediate reclaim is too mild
+ * a gain to justify taking an atomic operation penalty at the
+ * end of every folio writeback.
*/
- if (PageReclaim(page)) {
- struct folio *folio = page_folio(page);
- ClearPageReclaim(page);
+ if (folio_test_reclaim(folio)) {
+ folio_clear_reclaim(folio);
folio_rotate_reclaimable(folio);
}

/*
- * 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 folio_wake().
*/
- get_page(page);
- if (!test_clear_page_writeback(page))
+ folio_get(folio);
+ if (!test_clear_page_writeback(&folio->page))
BUG();

smp_mb__after_atomic();
- wake_up_page(page, PG_writeback);
- put_page(page);
+ folio_wake(folio, PG_writeback);
+ folio_put(folio);
}
-EXPORT_SYMBOL(end_page_writeback);
+EXPORT_SYMBOL(folio_end_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 91b3d00a92f7..526843d03d58 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -17,3 +17,9 @@ void unlock_page(struct page *page)
return folio_unlock(page_folio(page));
}
EXPORT_SYMBOL(unlock_page);
+
+void end_page_writeback(struct page *page)
+{
+ return folio_end_writeback(page_folio(page));
+}
+EXPORT_SYMBOL(end_page_writeback);
--
2.30.2