Hi Lidong,
On Sat, May 8, 2021 at 12:41 AM Zhong Lidong <lidong.zhong@xxxxxxxx> wrote:
>
> Hi Song,
>
> Could you share your opinion about this patch please?
>
The patch looks good to me. I will process it (run some tests etc)
later this week.
Thanks,
Song
>
> 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 {
> >
>
