Messages in this thread |  | | Date | Wed, 12 Nov 2014 12:59:33 -0500 | From | Chris Mason <> | Subject | Re: [PATCH] btrfs: Don't check for file->private_data on open(). It is set by the core. |
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On Wed, Nov 12, 2014 at 11:38 AM, Martin Kepplinger <martink@posteo.de> wrote: > The miscdevice core now sets file->private_data to the struct > miscdevice > so don't fail when this is not NULL. > > Signed-off-by: Martin Kepplinger <martink@posteo.de> > --- > This is a question: what does this check provide and does overwriting > file->private_data make any difference? > > Is miscdevice's open() by the user not allowed here, if > file->private_data > is set? > > thanks!!
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
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