From: Matthew Wilcox <willy@infradead.org>
To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
Jan Kara <jack@suse.cz>,
William Kucharski <william.kucharski@oracle.com>
Subject: [PATCH v3 10/11] mm: Use clear_bit_unlock_is_negative_byte for PageWriteback
Date: Thu, 16 Apr 2020 15:01:29 -0700 [thread overview]
Message-ID: <20200416220130.13343-11-willy@infradead.org> (raw)
In-Reply-To: <20200416220130.13343-1-willy@infradead.org>
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
We can use clear_bit_unlock_is_negative_byte() for writeback as well as
the lock bit. wake_up_page() then has no more callers and can be removed.
Given the other code being executed between the clear and the test,
this is not going to be as dramatic a win as it was for PageLocked,
but symmetry between the two is nice and lets us remove some code.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
---
include/linux/page-flags.h | 2 +-
mm/filemap.c | 12 ++----------
mm/page-writeback.c | 37 ++++++++++++++++++++-----------------
3 files changed, 23 insertions(+), 28 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index af7c0ff5f517..96c7d220c8cf 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -545,7 +545,7 @@ static __always_inline void SetPageUptodate(struct page *page)
CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
-int test_clear_page_writeback(struct page *page);
+bool __clear_page_writeback(struct page *page);
int __test_set_page_writeback(struct page *page, bool keep_write);
#define test_set_page_writeback(page) \
diff --git a/mm/filemap.c b/mm/filemap.c
index 401b24d980ba..c704d333d3bf 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1084,13 +1084,6 @@ 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)
-{
- if (!PageWaiters(page))
- return;
- wake_up_page_bit(page, bit);
-}
-
/*
* A choice of three behaviors for wait_on_page_bit_common():
*/
@@ -1293,9 +1286,8 @@ void end_page_writeback(struct page *page)
rotate_reclaimable_page(page);
}
- test_clear_page_writeback(page);
- smp_mb__after_atomic();
- wake_up_page(page, PG_writeback);
+ if (__clear_page_writeback(page))
+ wake_up_page_bit(page, PG_writeback);
}
EXPORT_SYMBOL(end_page_writeback);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ebaf0d8263a6..d019d86fc21f 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -595,7 +595,7 @@ static void wb_domain_writeout_inc(struct wb_domain *dom,
/*
* Increment @wb's writeout completion count and the global writeout
- * completion count. Called from test_clear_page_writeback().
+ * completion count.
*/
static inline void __wb_writeout_inc(struct bdi_writeback *wb)
{
@@ -2711,12 +2711,19 @@ int clear_page_dirty_for_io(struct page *page)
}
EXPORT_SYMBOL(clear_page_dirty_for_io);
-int test_clear_page_writeback(struct page *page)
+#define clear_writeback_bit(page) \
+ clear_bit_unlock_is_negative_byte(PG_writeback, &page->flags)
+
+/*
+ * The return value is whether there are waiters pending, not whether
+ * the flag was set.
+ */
+bool __clear_page_writeback(struct page *page)
{
struct address_space *mapping = page_mapping(page);
struct mem_cgroup *memcg;
struct lruvec *lruvec;
- int ret;
+ bool ret;
if (WARN_ON(!PageWriteback(page))) {
dump_page(page, "!writeback");
@@ -2731,16 +2738,14 @@ int test_clear_page_writeback(struct page *page)
unsigned long flags;
xa_lock_irqsave(&mapping->i_pages, flags);
- ret = TestClearPageWriteback(page);
- if (ret) {
- __xa_clear_mark(&mapping->i_pages, page_index(page),
+ ret = clear_writeback_bit(page);
+ __xa_clear_mark(&mapping->i_pages, page_index(page),
PAGECACHE_TAG_WRITEBACK);
- if (bdi_cap_account_writeback(bdi)) {
- struct bdi_writeback *wb = inode_to_wb(inode);
+ if (bdi_cap_account_writeback(bdi)) {
+ struct bdi_writeback *wb = inode_to_wb(inode);
- dec_wb_stat(wb, WB_WRITEBACK);
- __wb_writeout_inc(wb);
- }
+ dec_wb_stat(wb, WB_WRITEBACK);
+ __wb_writeout_inc(wb);
}
if (mapping->host && !mapping_tagged(mapping,
@@ -2749,7 +2754,7 @@ int test_clear_page_writeback(struct page *page)
xa_unlock_irqrestore(&mapping->i_pages, flags);
} else {
- ret = TestClearPageWriteback(page);
+ ret = clear_writeback_bit(page);
}
/*
* NOTE: Page might be free now! Writeback doesn't hold a page
@@ -2757,11 +2762,9 @@ int test_clear_page_writeback(struct page *page)
* the clearing of PG_writeback. The below can only access
* page state that is static across allocation cycles.
*/
- if (ret) {
- dec_lruvec_state(lruvec, NR_WRITEBACK);
- dec_zone_page_state(page, NR_ZONE_WRITE_PENDING);
- inc_node_page_state(page, NR_WRITTEN);
- }
+ dec_lruvec_state(lruvec, NR_WRITEBACK);
+ dec_zone_page_state(page, NR_ZONE_WRITE_PENDING);
+ inc_node_page_state(page, NR_WRITTEN);
__unlock_page_memcg(memcg);
return ret;
}
--
2.25.1
next prev parent reply other threads:[~2020-04-16 22:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 22:01 [PATCH v3 00/11] Make PageWriteback use the PageLocked optimisation Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 01/11] alpha: Add clear_bit_unlock_is_negative_byte implementation Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 02/11] ia64: " Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 03/11] m68k: " Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 04/11] mips: " Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 05/11] riscv: " Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 06/11] s390: " Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 07/11] mm: Remove definition of clear_bit_unlock_is_negative_byte Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 08/11] mm: Move PG_writeback into the bottom byte Matthew Wilcox
2020-04-16 22:01 ` [PATCH v3 09/11] mm: Convert writeback BUG to WARN_ON Matthew Wilcox
2020-04-23 15:58 ` Jan Kara
2020-04-16 22:01 ` Matthew Wilcox [this message]
2020-04-16 22:01 ` [PATCH v3 11/11] mm: Remove TestClearPageWriteback Matthew Wilcox
2020-04-17 7:28 ` [PATCH v3 00/11] Make PageWriteback use the PageLocked optimisation Geert Uytterhoeven
2020-04-17 11:12 ` Matthew Wilcox
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