linux-kernel - [f2fs-dev] [PATCH 2/3] f2fs: avoid unneeded page release for correct

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Message-id: <001801cef15d$2e3e4b10$8abae130$@samsung.com>
Date:	Thu, 05 Dec 2013 09:54:56 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	??? <jaegeuk.kim@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	谭姝 <shu.tan@...sung.com>
Subject: [f2fs-dev] [PATCH 2/3] f2fs: avoid unneeded page release for correct
 _count of page

In find_fsync_dnodes() and recover_data(), our flow is like this:

->f2fs_submit_page_bio()
	-> f2fs_put_page()
		-> page_cache_release()	---- page->_count declined to zero.
->__free_pages()
	-> put_page_testzero() ---- page->_count will be declined again.

We will get a segment fault in put_page_testzero when CONFIG_DEBUG_VM
is on, or return MM with a bad page with wrong _count num.

So let's just release this page.

Signed-off-by: Chao Yu <chao2.yu@...sung.com>
---
 fs/f2fs/recovery.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index 7dda1f28..d075465 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -145,7 +145,7 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head)
 
 		err = f2fs_submit_page_bio(sbi, page, blkaddr, READ_SYNC);
 		if (err)
-			goto out;
+			return err;
 
 		lock_page(page);
 
@@ -191,9 +191,10 @@ next:
 		/* check next segment */
 		blkaddr = next_blkaddr_of_node(page);
 	}
+
 	unlock_page(page);
-out:
 	__free_pages(page, 0);
+
 	return err;
 }
 
@@ -388,7 +389,7 @@ static int recover_data(struct f2fs_sb_info *sbi,
 
 		err = f2fs_submit_page_bio(sbi, page, blkaddr, READ_SYNC);
 		if (err)
-			goto out;
+			return err;
 
 		lock_page(page);
 
@@ -412,8 +413,8 @@ next:
 		/* check next segment */
 		blkaddr = next_blkaddr_of_node(page);
 	}
+
 	unlock_page(page);
-out:
 	__free_pages(page, 0);
 
 	if (!err)
-- 
1.7.9.5

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