On Wed, Sep 27, 2023 at 11:22 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> Advantages for new apis:
> - reconfig_mutex is not required;
> - the weird logical that suspend array hold 'reconfig_mutex' for
> mddev_check_recovery() to update superblock is not needed;
> - the specail handling, 'pers->prepare_suspend', for raid456 is not
> needed;
> - It's safe to be called at any time once mddev is allocated, and it's
> designed to be used from slow path where array configuration is changed;
> - the new helpers is designed to be called before mddev_lock(), hence
> it support to be interrupted by user as well.
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> drivers/md/md.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++-
> drivers/md/md.h | 3 ++
> 2 files changed, 103 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index e460b380143d..a075d03d03d3 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -443,12 +443,22 @@ void mddev_suspend(struct mddev *mddev)
> lockdep_is_held(&mddev->reconfig_mutex));
>
> WARN_ON_ONCE(thread && current == thread->tsk);
> - if (mddev->suspended++)
> +
> + /* can't concurrent with __mddev_suspend() and __mddev_resume() */
> + mutex_lock(&mddev->suspend_mutex);
> + if (mddev->suspended++) {
> + mutex_unlock(&mddev->suspend_mutex);
> return;
Can we make mddev->suspended atomic_t, and use atomic_inc_return()
here?
Thanks,
Song
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