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From:   Chao Yu <chao@kernel.org>
To:     jaegeuk@kernel.org
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, Chao Yu <chao@kernel.org>,
        syzbot+ebd7072191e2eddd7d6e@syzkaller.appspotmail.com
Subject: [PATCH] f2fs: fix to drop meta_inode's page cache in f2fs_put_super()
Date:   Tue,  5 Sep 2023 12:57:53 +0800
Message-Id: <20230905045753.24964-1-chao@kernel.org>
MIME-Version: 1.0
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syzbot reports a kernel bug as below:

F2FS-fs (loop1): detect filesystem reference count leak during umount, type: 10, count: 1
kernel BUG at fs/f2fs/super.c:1639!
CPU: 0 PID: 15451 Comm: syz-executor.1 Not tainted 6.5.0-syzkaller-09338-ge0152e7481c6 #0
RIP: 0010:f2fs_put_super+0xce1/0xed0 fs/f2fs/super.c:1639
Call Trace:
 generic_shutdown_super+0x161/0x3c0 fs/super.c:693
 kill_block_super+0x3b/0x70 fs/super.c:1646
 kill_f2fs_super+0x2b7/0x3d0 fs/f2fs/super.c:4879
 deactivate_locked_super+0x9a/0x170 fs/super.c:481
 deactivate_super+0xde/0x100 fs/super.c:514
 cleanup_mnt+0x222/0x3d0 fs/namespace.c:1254
 task_work_run+0x14d/0x240 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
 do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

In f2fs_put_super(), it tries to do sanity check on dirty and IO
reference count of f2fs, once there is any reference count leak,
it will trigger panic.

The root case is, during f2fs_put_super(), if there is any IO error
in f2fs_wait_on_all_pages(), we missed to truncate meta_inode's page
cache later, result in panic, fix this case.

Fixes: 20872584b8c0 ("f2fs: fix to drop all dirty meta/node pages during umount()")
Reported-by: syzbot+ebd7072191e2eddd7d6e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-f2fs-devel/000000000000a14f020604a62a98@google.com
Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 9ef9d5baece0..973184f267cb 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1675,7 +1675,7 @@ static void f2fs_put_super(struct super_block *sb)
 
 	f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);
 
-	if (err) {
+	if (err || f2fs_cp_error(sbi)) {
 		truncate_inode_pages_final(NODE_MAPPING(sbi));
 		truncate_inode_pages_final(META_MAPPING(sbi));
 	}
-- 
2.40.1