From: Al Viro <viro@ZenIV.linux.org.uk>
To: Martin Kepplinger <martink@posteo.de>
Cc: Chris Mason <clm@fb.com>,
linux-btrfs@vger.kernel.org, gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] btrfs: Don't check for file->private_data on open(). It is set by the core.
Date: Thu, 13 Nov 2014 22:14:41 +0000 [thread overview]
Message-ID: <20141113221441.GL7996@ZenIV.linux.org.uk> (raw)
In-Reply-To: <5463A84A.8010606@posteo.de>
On Wed, Nov 12, 2014 at 07:34:50PM +0100, Martin Kepplinger wrote:
> > Btrfs uses this in the transaction start ioctl to record the transaction
> > handle being started. Ceph is the main user of the ioctl, and we could
> > setup a hash table if needed. But which call path in miscdevice is
> > doing this?
> >
> > With your patch in place, btrfs would end up overwriting the miscdevice
> > private_data field, which would probably cause problems.
> >
> > -chris
> >
>
> I think i was mistaken, sorry. misc_open() used to set
> file->private_data _only_ if you use set .open in struct file_operations.
>
> In current -next this changed and file->private_data is set to struct
> miscdevice on a (userspace's) open call (misc_open()) just in any case.
>
> You do set .open so this wouldn't affect you and this patch can be ignored.
More to the point, this function is not reachable from anything in
file_operations of any miscdevice. btrfs_ioctl != btrfs_control_ioctl...
prev parent reply other threads:[~2014-11-13 22:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-12 16:38 [PATCH] btrfs: Don't check for file->private_data on open(). It is set by the core Martin Kepplinger
2014-11-12 17:59 ` Chris Mason
2014-11-12 18:34 ` Martin Kepplinger
2014-11-13 22:14 ` Al Viro [this message]
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