From 4ebd3aec3842662300979dacd6fb38e3e8edf7f4 Mon Sep 17 00:00:00 2001
From: Yang Guo <guoyang2@huawei.com>
Date: Wed, 24 Feb 2021 12:02:48 -0800
Subject: fs/buffer.c: add checking buffer head stat before clear
clear_buffer_new() is used to clear buffer new stat. When PAGE_SIZE is
64K, most buffer heads in the list are not needed to clear.
clear_buffer_new() has an enpensive atomic modification operation, Let's
add checking buffer head before clear it as __block_write_begin_int does
which is good for performance.
Link: https://lkml.kernel.org/r/1612332890-57918-1-git-send-email-zhangshaokun@hisilicon.com
Signed-off-by: Yang Guo <guoyang2@huawei.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/buffer.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
(limited to 'fs/buffer.c')
diff --git a/fs/buffer.c b/fs/buffer.c
index 32647d2011df..f1c3a5b27a90 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2083,7 +2083,8 @@ static int __block_commit_write(struct inode *inode, struct page *page,
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
}
- clear_buffer_new(bh);
+ if (buffer_new(bh))
+ clear_buffer_new(bh);
block_start = block_end;
bh = bh->b_this_page;
--
cgit v1.2.3
From 6eeb104e114cb6b7391c2d69ff873403858c1f35 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
Date: Wed, 24 Feb 2021 12:04:15 -0800
Subject: fs: buffer: use raw page_memcg() on locked page
alloc_page_buffers() currently uses get_mem_cgroup_from_page() for
charging the buffers to the page owner, which does an rcu-protected
page->memcg lookup and acquires a reference. But buffer allocation has
the page lock held throughout, which pins the page to the memcg and
thereby the memcg - neither rcu nor holding an extra reference during the
allocation are necessary. Use a raw page_memcg() instead.
This was the last user of get_mem_cgroup_from_page(), delete it.
Link: https://lkml.kernel.org/r/20210209190126.97842-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/buffer.c | 4 ++--
include/linux/memcontrol.h | 7 -------
mm/memcontrol.c | 23 -----------------------
3 files changed, 2 insertions(+), 32 deletions(-)
(limited to 'fs/buffer.c')
diff --git a/fs/buffer.c b/fs/buffer.c
index f1c3a5b27a90..0cb7ffd4977c 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -847,7 +847,8 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
if (retry)
gfp |= __GFP_NOFAIL;
- memcg = get_mem_cgroup_from_page(page);
+ /* The page lock pins the memcg */
+ memcg = page_memcg(page);
old_memcg = set_active_memcg(memcg);
head = NULL;
@@ -868,7 +869,6 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
}
out:
set_active_memcg(old_memcg);
- mem_cgroup_put(memcg);
return head;
/*
* In case anything failed, we just free everything we got.
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 7a38a1517a05..e6dc793d587d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -680,8 +680,6 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
-struct mem_cgroup *get_mem_cgroup_from_page(struct page *page);
-
struct lruvec *lock_page_lruvec(struct page *page);
struct lruvec *lock_page_lruvec_irq(struct page *page);
struct lruvec *lock_page_lruvec_irqsave(struct page *page,
@@ -1191,11 +1189,6 @@ static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
return NULL;
}
-static inline struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
-{
- return NULL;
-}
-
static inline void mem_cgroup_put(struct mem_cgroup *memcg)
{
}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8c035846c7a4..7fdc001ce15f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1047,29 +1047,6 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
}
EXPORT_SYMBOL(get_mem_cgroup_from_mm);
-/**
- * get_mem_cgroup_from_page: Obtain a reference on given page's memcg.
- * @page: page from which memcg should be extracted.
- *
- * Obtain a reference on page->memcg and returns it if successful. Otherwise
- * root_mem_cgroup is returned.
- */
-struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
-{
- struct mem_cgroup *memcg = page_memcg(page);
-
- if (mem_cgroup_disabled())
- return NULL;
-
- rcu_read_lock();
- /* Page should not get uncharged and freed memcg under us. */
- if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css)))
- memcg = root_mem_cgroup;
- rcu_read_unlock();
- return memcg;
-}
-EXPORT_SYMBOL(get_mem_cgroup_from_page);
-
static __always_inline struct mem_cgroup *active_memcg(void)
{
if (in_interrupt())
--
cgit v1.2.3