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Date: Wed, 03 Apr 2013 17:12:49 +0900
From: Jaegeuk Kim <jaegeuk.kim@...sung.com>
To: Namjae Jeon <linkinjeon@...il.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH 3/9 v2] f2fs: remove redundant lock_page calls
Hi,
Agreed, and send v2.
Change log from v1:
o remain read_node_page and remove the lock part
From 04006aecac2882c574fe8a7de926bc52c73a8ad1 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk.kim@...sung.com>
Date: Sun, 31 Mar 2013 12:47:20 +0900
Subject: [PATCH] f2fs: remove redundant lock_page calls
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
In get_node_page, we do not need to call lock_page all the time.
If the node page is cached as uptodate,
1. grab_cache_page locks the page,
2. read_node_page unlocks the page, and
3. lock_page is called for further process.
Let's avoid this.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
---
fs/f2fs/node.c | 44 +++++++++++++++++++++++++++-----------------
fs/f2fs/node.h | 3 +++
2 files changed, 30 insertions(+), 17 deletions(-)
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 10cbee9..e3484b5 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -847,6 +847,12 @@ fail:
return ERR_PTR(err);
}
+/*
+ * Caller should do after getting the following values.
+ * 0: f2fs_put_page(page, 0)
+ * LOCKED_PAGE: f2fs_put_page(page, 1)
+ * error: nothing
+ */
static int read_node_page(struct page *page, int type)
{
struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
@@ -859,10 +865,8 @@ static int read_node_page(struct page *page, int
type)
return -ENOENT;
}
- if (PageUptodate(page)) {
- unlock_page(page);
- return 0;
- }
+ if (PageUptodate(page))
+ return LOCKED_PAGE;
return f2fs_readpage(sbi, page, ni.blk_addr, type);
}
@@ -874,6 +878,7 @@ void ra_node_page(struct f2fs_sb_info *sbi, nid_t
nid)
{
struct address_space *mapping = sbi->node_inode->i_mapping;
struct page *apage;
+ int err;
apage = find_get_page(mapping, nid);
if (apage && PageUptodate(apage)) {
@@ -886,30 +891,36 @@ void ra_node_page(struct f2fs_sb_info *sbi, nid_t
nid)
if (!apage)
return;
- if (read_node_page(apage, READA) == 0)
+ err = read_node_page(page, READA);
+ if (err == 0)
f2fs_put_page(apage, 0);
+ else if (err == LOCKED_PAGE)
+ f2fs_put_page(apage, 1);
return;
}
struct page *get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid)
{
- int err;
- struct page *page;
struct address_space *mapping = sbi->node_inode->i_mapping;
+ struct page *page;
+ int err;
page = grab_cache_page(mapping, nid);
if (!page)
return ERR_PTR(-ENOMEM);
err = read_node_page(page, READ_SYNC);
- if (err)
- return ERR_PTR(err);
+ if (err < 0)
+ return ERR_PTR(ret);
+ else if (err == LOCKED_PAGE)
+ goto got_it;
lock_page(page);
if (!PageUptodate(page)) {
f2fs_put_page(page, 1);
return ERR_PTR(-EIO);
}
+got_it:
BUG_ON(nid != nid_of_node(page));
mark_page_accessed(page);
return page;
@@ -923,10 +934,9 @@ struct page *get_node_page_ra(struct page *parent,
int start)
{
struct f2fs_sb_info *sbi = F2FS_SB(parent->mapping->host->i_sb);
struct address_space *mapping = sbi->node_inode->i_mapping;
- int i, end;
- int err = 0;
- nid_t nid;
struct page *page;
+ int err, i, end;
+ nid_t nid;
/* First, try getting the desired direct node. */
nid = get_nid(parent, start, false);
@@ -936,12 +946,12 @@ struct page *get_node_page_ra(struct page *parent,
int start)
page = grab_cache_page(mapping, nid);
if (!page)
return ERR_PTR(-ENOMEM);
- else if (PageUptodate(page))
- goto page_hit;
err = read_node_page(page, READ_SYNC);
- if (err)
- return ERR_PTR(err);
+ if (err < 0)
+ return ERR_PTR(ret);
+ else if (err == LOCKED_PAGE)
+ goto page_hit;
/* Then, try readahead for siblings of the desired node */
end = start + MAX_RA_NODE;
@@ -956,7 +966,7 @@ struct page *get_node_page_ra(struct page *parent,
int start)
lock_page(page);
page_hit:
- if (PageError(page)) {
+ if (!PageUptodate(page)) {
f2fs_put_page(page, 1);
return ERR_PTR(-EIO);
}
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index d009cdf..271a61c 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -29,6 +29,9 @@
/* vector size for gang look-up from nat cache that consists of radix
tree */
#define NATVEC_SIZE 64
+/* return value for read_node_page */
+#define LOCKED_PAGE 1
+
/*
* For node information
*/
--
1.8.1.3.566.gaa39828
--
Jaegeuk Kim
Samsung
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