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    Subject[PATCH AUTOSEL 6.1 21/38] fscache: Use clear_and_wake_up_bit() in fscache_create_volume_work()
    Date
    From: Hou Tao <houtao1@huawei.com>

    [ Upstream commit 3288666c72568fe1cc7f5c5ae33dfd3ab18004c8 ]

    fscache_create_volume_work() uses wake_up_bit() to wake up the processes
    which are waiting for the completion of volume creation. According to
    comments in wake_up_bit() and waitqueue_active(), an extra smp_mb() is
    needed to guarantee the memory order between FSCACHE_VOLUME_CREATING
    flag and waitqueue_active() before invoking wake_up_bit().

    Fixing it by using clear_and_wake_up_bit() to add the missing memory
    barrier.

    Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
    Signed-off-by: Hou Tao <houtao1@huawei.com>
    Signed-off-by: David Howells <dhowells@redhat.com>
    Reviewed-by: Jeff Layton <jlayton@kernel.org>
    Link: https://lore.kernel.org/r/20230113115211.2895845-3-houtao@huaweicloud.com/ # v3
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/fscache/volume.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/fs/fscache/volume.c b/fs/fscache/volume.c
    index ab8ceddf9efad..d9fdd90668b0f 100644
    --- a/fs/fscache/volume.c
    +++ b/fs/fscache/volume.c
    @@ -279,8 +279,7 @@ static void fscache_create_volume_work(struct work_struct *work)
    fscache_end_cache_access(volume->cache,
    fscache_access_acquire_volume_end);

    - clear_bit_unlock(FSCACHE_VOLUME_CREATING, &volume->flags);
    - wake_up_bit(&volume->flags, FSCACHE_VOLUME_CREATING);
    + clear_and_wake_up_bit(FSCACHE_VOLUME_CREATING, &volume->flags);
    fscache_put_volume(volume, fscache_volume_put_create_work);
    }

    --
    2.39.0
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