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Subject[f2fs-dev] [PATCH 2/3] f2fs: avoid unneeded page release for correct _count of page
Date
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@samsung.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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