On Fri 27-11-20 16:36:15, Christoph Hellwig wrote:
> On Fri, Nov 27, 2020 at 01:45:37PM +0100, Jan Kara wrote:
> > > At this point the hd_struct is already allocated together with the
> > > block_device, and thus only freed after the last block_device reference
> > > goes away plus the inode freeing RCU grace period. So the device model
> > > ref to part is indeed gone, but that simply does not matter any more.
> >
> > Well, but once device model ref to part is gone, we're going to free the
> > bdev inode ref as well. Thus there's nothing which pins the bdev containing
> > hd_struct?
> >
> > But now as I'm thinking about it you later switch the device model reference
> > to just pure inode reference and use igrab() which will reliably return
> > NULL if the inode is on it's way to be destroyed so probably we are safe in
> > the final state.
>
> igrab always succeeds. But we should switch to a tryget.
No. If the inode is I_FREEING or I_WILL_FREE, it will return NULL...
Honza
--
Jan Kara <j...@suse.com>
SUSE Labs, CR
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