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    Subject[PATCH] f2fs: avoid race condition for shinker count
    Date
    Light reported sometimes shinker gets nat_cnt < dirty_nat_cnt resulting in
    wrong do_shinker work. Basically the two counts should not happen like that.

    So, I suspect this race condtion where:
    - f2fs_try_to_free_nats __flush_nat_entry_set
    nat_cnt=2, dirty_nat_cnt=2
    __clear_nat_cache_dirty
    spin_lock(nat_list_lock)
    list_move()
    spin_unlock(nat_list_lock)
    spin_lock(nat_list_lock)
    list_del()
    spin_unlock(nat_list_lock)
    nat_cnt=1, dirty_nat_cnt=2
    nat_cnt=1, dirty_nat_cnt=1

    Reported-by: Light Hsieh <Light.Hsieh@mediatek.com>
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    ---
    fs/f2fs/node.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
    index 42394de6c7eb..e8ec65e40f06 100644
    --- a/fs/f2fs/node.c
    +++ b/fs/f2fs/node.c
    @@ -269,11 +269,10 @@ static void __clear_nat_cache_dirty(struct f2fs_nm_info *nm_i,
    {
    spin_lock(&nm_i->nat_list_lock);
    list_move_tail(&ne->list, &nm_i->nat_entries);
    - spin_unlock(&nm_i->nat_list_lock);
    -
    set_nat_flag(ne, IS_DIRTY, false);
    set->entry_cnt--;
    nm_i->dirty_nat_cnt--;
    + spin_unlock(&nm_i->nat_list_lock);
    }

    static unsigned int __gang_lookup_nat_set(struct f2fs_nm_info *nm_i,
    --
    2.29.2.222.g5d2a92d10f8-goog
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