On Thu, Jan 09, 2014 at 04:50:12PM -0500, Steven Rostedt wrote:

quoted

We'd then have to get rid of all the call_rcu() invocations in individual
filesystems' destroy_inode methods, but that doesn't sound like a bad
thing to me.

Check what e.g. XFS is doing...

Which is another reason that I didn't do it, as I didn't know all the
happenings inside the ->destroy_inode() calls. But yeah, I agree with
this.

Also, can iput() sleep? If not then we are OK. Otherwise, we need to be
careful about any mutex being grabbed in those call backs, as the
rcu_callback can't sleep either.

iput() definitely can sleep (that's when actual truncation and inode
freeing is done for opened-and-unlinked files - on the final iput() after
close()), but that' irrelevant here - fsnotify_delete_inode() grabs
a bunch of mutexes, which makes calling it from rcu callback no-go.