[bug report] compiler warning: fs/f2fs/node.c: In function ‘__set_nat_cache_dirty’: ‘head’ may be used uninitialized

["Ardelean, Alexandru" <alexandru.Ardelean@analog.com>]

Seems to have been introduced via:

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commit 780de47cf6cb5f524cd98ec8ffbffc3da5696e17
Author: Chao Yu <yuchao0@huawei.com>
Date:   Tue Mar 20 23:08:30 2018 +0800

    f2fs: don't track new nat entry in nat set
    
    Nat entry set is used only in checkpoint(), and during checkpoint() we
    won't flush new nat entry with unallocated address, so we don't need to
    add new nat entry into nat set, then nat_entry_set::entry_cnt can
    indicate actual entry count we need to flush in checkpoint().
    
    Signed-off-by: Yunlei He <heyunlei@huawei.com>
    Signed-off-by: Chao Yu <yuchao0@huawei.com>
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Compiler warning is:
----------------------------------------------------------------

  CC      fs/f2fs/node.o
In file included from ./include/linux/wait.h:7:0,
                 from ./include/linux/wait_bit.h:8,
                 from ./include/linux/fs.h:6,
                 from fs/f2fs/node.c:11:
fs/f2fs/node.c: In function ‘__set_nat_cache_dirty’:
./include/linux/list.h:63:13: error: ‘head’ may be used uninitialized in
this function [-Werror=maybe-uninitialized]
  next->prev = new;
             ^
fs/f2fs/node.c:238:24: note: ‘head’ was declared here
  struct nat_entry_set *head;
                        ^
cc1: all warnings being treated as errors
----------------------------------------------------------------

Thanks
Alex