On Mon, Apr 15, 2024 at 10:35:53PM +0800, Ming Lei wrote:
> On Mon, Apr 15, 2024 at 02:35:17PM +0200, Christian Brauner wrote:
> > On Mon, Apr 15, 2024 at 05:26:19PM +0800, Ming Lei wrote:
> > > Hello,
> > >
> > > On Tue, Jan 23, 2024 at 02:26:21PM +0100, Christian Brauner wrote:
> > > > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
> > > > ---
> > > > drivers/md/dm.c | 23 +++++++++++++----------
> > > > drivers/md/md.c | 12 ++++++------
> > > > drivers/md/md.h | 2 +-
> > > > include/linux/device-mapper.h | 2 +-
> > > > 4 files changed, 21 insertions(+), 18 deletions(-)
> > > >
> > > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> > > > index 8dcabf84d866..87de5b5682ad 100644
> > > > --- a/drivers/md/dm.c
> > > > +++ b/drivers/md/dm.c
> > >
> > > ...
> > >
> > > > @@ -775,7 +778,7 @@ static void close_table_device(struct table_device *td, struct mapped_device *md
> > > > {
> > > > if (md->disk->slave_dir)
> > > > bd_unlink_disk_holder(td->dm_dev.bdev, md->disk);
> > > > - bdev_release(td->dm_dev.bdev_handle);
> > > > + fput(td->dm_dev.bdev_file);
> > >
> > > The above change caused regression on 'dmsetup remove_all'.
> > >
> > > blkdev_release() is delayed because of fput(), so dm_lock_for_deletion
> > > returns -EBUSY, then this dm disk is skipped in remove_all().
> > >
> > > Force to mark DMF_DEFERRED_REMOVE might solve it, but need our device
> > > mapper guys to check if it is safe.
> > >
> > > Or other better solution?
> >
> > Yeah, I think there is. You can just switch all fput() instances in
> > device mapper to bdev_fput() which is mainline now. This will yield the
> > device and make it able to be reclaimed. Should be as simple as the
> > patch below. Could you test this and send a patch based on this (I'm on
> > a prolonged vacation so I don't have time right now.):
>
> Unfortunately it doesn't work.
>
> Here the problem is that blkdev_release() is delayed, which changes
> 'dmsetup remove_all' behavior, and causes that some of dm disks aren't
> removed.
>
> Please see dm_lock_for_deletion() and dm_blk_open()/dm_blk_close().
So you really need blkdev_release() itself to be synchronous? Groan, in
that case use __fput_sync() instead of fput() which ensures that this
file is closed synchronously.
