linux-kernel - [PATCH] f2fs: fix out-of-free problem caused by atomic write

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Date:   Thu, 26 Oct 2017 22:21:55 +0800
From:   Yunlong Song <yunlong.song@...wei.com>
To:     <jaegeuk@...nel.org>, <chao@...nel.org>, <yuchao0@...wei.com>,
        <yunlong.song@...oud.com>, <yunlong.song@...wei.com>
CC:     <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] f2fs: fix out-of-free problem caused by atomic write

f2fs_balance_fs only actives once in the commit_inmem_pages, but there
are more than one page to commit, so all the other pages will miss the
check. This will lead to out-of-free problem when commit a very large
file. To fix it, we should do f2fs_balance_fs for each inmem page.

Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
---
 fs/f2fs/segment.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 46dfbca..fa2c36b 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -384,6 +384,9 @@ static int __commit_inmem_pages(struct inode *inode,
 				unlock_page(page);
 				break;
 			}
+			f2fs_unlock_op(sbi);
+			f2fs_balance_fs(sbi, true);
+			f2fs_lock_op(sbi);
 			/* record old blkaddr for revoking */
 			cur->old_addr = fio.old_blkaddr;
 			last_idx = page->index;
@@ -409,7 +412,6 @@ int commit_inmem_pages(struct inode *inode)
 	int err;
 
 	INIT_LIST_HEAD(&revoke_list);
-	f2fs_balance_fs(sbi, true);
 	f2fs_lock_op(sbi);
 
 	set_inode_flag(inode, FI_ATOMIC_COMMIT);
-- 
1.8.5.2