Al Viro <viro@xxxxxxxxxxxxxxxxxx> 于2022年6月23日周四 11:48写道： > > On Thu, Jun 23, 2022 at 11:44:29AM +0800, sunliming wrote: > > Al Viro <viro@xxxxxxxxxxxxxxxxxx> 于2022年6月22日周三 18:35写道： > > > > > > On Wed, Jun 22, 2022 at 04:51:46PM +0800, sunliming wrote: > > > > The inode variable is used as a parameter by the step_into function, > > > > but is not assigned a value in the sub-lookup_slow branch path. So > > > > get the inode in the sub-lookup_slow branch path. > > > > > > Take a good look at handle_mounts() and the things it does when > > > *not* in RCU mode (i.e. LOOKUP_RCU is not set). Specifically, > > > *inode = d_backing_inode(path->dentry); > > > *seqp = 0; /* out of RCU mode, so the value doesn't matter */ > > > this part. > > > > > > IOW, the values passed to step_into() in inode/seq are overridden unless > > > we stay in RCU mode. And if we'd been through lookup_slow(), we'd been > > > out of RCU mode since before we called step_into(). > > > > It might be more appropriate and easier to understand to do this > > before parameter passing in the top-level walk_component function？ > > It's possible to fall out of RCU mode *inside* step_into(), so we need > it done there anyway. Unfortunately ;-/ Thanks for your explanation
