On Wed, Mar 19, 2008 at 05:41:15PM +0100, Miklos Szeredi wrote: > > > From: Miklos Szeredi <mszeredi@xxxxxxx> > > Um? Do you ever need to take it outside of vfsmount_lock? > > > > Tried to think this through: > > It's always called with namespace_sem, which is enough, no need for a > new lock. The bigger problem, is that it _is_ called with > vfsmount_lock in one case, which is bad, since the allocation may > sleep. It is called with vfsmount_lock in *all* cases. You've missed one in umount_tree(), BTW; you won't block in that case, though. > That is in do_change_type(). But do we really need to hold > vfsmount_lock in that case? Not the issue. > I think not, the propagation tree has no > relevance outside namespace_sem, so that one should be sufficient. Callers manipulate more than propagation tree. Note that e.g. umount_tree() changes all sorts of data structures, including ones that are traversed without namespace_sem. I _really_ don't like the idea of different locking rules for caller of a function depending on the value of argument of that function. They are complicated enough as it is. Argh... OK, I'll try to put something together tonight, after I get some sleep - 31 hours of uptime _suck_ ;-/ BTW, on top of everything else, the current variant plays interesting games with CL_PROPAGATION behaviour and I really don't like the look of what it's doing there. Later... -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
