Hello,

syzbot has tested the proposed patch and the reproducer did not trigger  
crash:

Reported-and-tested-by:  
syzbot+8ec30bb7bf1a981a2012@syzkaller.appspotmail.com

Note: the tag will also help syzbot to understand when the bug is fixed.

Tested on upstream commit
3da90b159b146672f830bcd2489dd3a1f4e9e089 (Wed Jan 31 03:07:32 2018 +0000)
Merge tag 'f2fs-for-4.16-rc1' of  
git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

compiler: gcc (GCC) 7.1.1 20170620
Patch is attached.
Kernel config is attached.


---
There is no WARRANTY for the result, to the extent permitted by applicable  
law.
Except when otherwise stated in writing syzbot provides the result "AS IS"
without warranty of any kind, either expressed or implied, but not limited  
to,
the implied warranties of merchantability and fittness for a particular  
purpose.
The entire risk as to the quality of the result is with you. Should the  
result
prove defective, you assume the cost of all necessary servicing, repair or
correction.