Hi Song,
Could you share your opinion about this patch please?
Thanks,
Lidong
On 4/28/21 4:29 PM, Lidong Zhong wrote:
> The mddev data structure is freed in mddev_delayed_delete(), which is
> schedualed after the array is deconfigured completely when stopping. So
> there is a race window between md_open() and do_md_stop(), which leads
> to /dev/mdX can still be opened by userspace even it's not accessible
> any more. As a result, a DeviceDisappeared event will not be able to be
> monitored by mdadm in monitor mode. This patch tries to fix it by adding
> this new flag MD_DELETING.
>
> Signed-off-by: Lidong Zhong <lidong.zhong@xxxxxxxx>
> ---
> drivers/md/md.c | 4 +++-
> drivers/md/md.h | 2 ++
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 21da0c48f6c2..566df2491318 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -6439,6 +6439,7 @@ static int do_md_stop(struct mddev *mddev, int mode,
> md_clean(mddev);
> if (mddev->hold_active == UNTIL_STOP)
> mddev->hold_active = 0;
> + set_bit(MD_DELETING, &mddev->flags);
> }
> md_new_event(mddev);
> sysfs_notify_dirent_safe(mddev->sysfs_state);
> @@ -7829,7 +7830,8 @@ static int md_open(struct block_device *bdev, fmode_t mode)
> if ((err = mutex_lock_interruptible(&mddev->open_mutex)))
> goto out;
>
> - if (test_bit(MD_CLOSING, &mddev->flags)) {
> + if (test_bit(MD_CLOSING, &mddev->flags) ||
> + (test_bit(MD_DELETING, &mddev->flags) && mddev->pers == NULL)) {
> mutex_unlock(&mddev->open_mutex);
> err = -ENODEV;
> goto out;
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index bcbba1b5ec4a..83c7aa61699f 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -262,6 +262,8 @@ enum mddev_flags {
> MD_BROKEN, /* This is used in RAID-0/LINEAR only, to stop
> * I/O in case an array member is gone/failed.
> */
> + MD_DELETING, /* If set, we are deleting the array, do not open
> + * it then */
> };
>
> enum mddev_sb_flags {
>
