Re: Freeing vnodes.

From: David Schultz (das_at_FreeBSD.ORG)
Date: 03/29/05

  • Next message: Jeff Roberson: "Re: Freeing vnodes." 
    Date: Tue, 29 Mar 2005 02:10:06 -0500
To: Jeff Roberson <jroberson@chesapeake.net>

    On Tue, Mar 29, 2005, Jeff Roberson wrote:
    > On Tue, 29 Mar 2005, Jeff Roberson wrote:
    >
    > > On Mon, 28 Mar 2005, David Schultz wrote:
    > >
    > > > On Mon, Mar 28, 2005, Jeff Roberson wrote:
    > > > > > > I am worried about the v_dd,v_ddid fields of a directory B that has the
    > > > > > > to be released vnode A as parent. (Obviously in this case there is no
    > > > > > > namecache entry with the vnode A as the directory (nc_dvp))
    > > > > > >
    > > > > > > Right now A is type stable - but if A is released, access to B->v_dd
    > > > > > > may cause a page fault.
    > > > > > >
    > > > > > > Stephan
    > > > > >
    > > > > > Jeff,
    > > > > >
    > > > > > Do you plan to address the problem now that the code is checked in?
    > > > >
    > > > > Vnodes with children in the name cache are held with vhold() and not
    > > > > recycled.
    > > >
    > > > Yes, but cache_purge() is called directly in a number of places
    > > > where the vnode may have children, e.g. in mount. So dangling
    > > > references might still be possible unless cache_purge() fixes up
    > > > the children's v_dd pointers appropriately.
    > > >
    > >
    > > ah, indeed. How does this look:
    >
    > Also, are the ids really necessary now that we don't reuse vnodes?
    > Shouldn't the pointer be sufficient?

    I think so. The patch I sent you a few days ago gets rid of v_id
    except in vfs_cache_lookup(), where it is used to guarantee that
    the vnode hasn't changed while sleeping in vn_lock(). With vnode
    reclamation, that isn't safe anyway, so if you fix vfs_cache_lookup(),
    we can kill v_id completely.

    Your patch looks okay at a glance, but shouldn't you be iterating over
    v_cache_src instead of v_cache_dst?
    _______________________________________________
    freebsd-arch@freebsd.org mailing list
    http://lists.freebsd.org/mailman/listinfo/freebsd-arch
    To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org"

  • Next message: Jeff Roberson: "Re: Freeing vnodes."

    Relevant Pages

    • Re: panic: getnewvnode: free vnode isnt
      ... >> Could people seeing this panic try the following patch? ... >> callers of vcleanensure that the vnode is not on the free list, ... > The patch hasn't stopped the panics, but I've tracked down a series of ... I've just started using USB keyboard/mouse and a KVM. ...
      (freebsd-current)
    • Re: jail getfsstat patches.
      ... > The best way to do it is to walk up from the vnode where file system is ... > mounted on to the vnode where jail's root directory starts. ... > patch to commit so we can review it together. ... I'd rather see it built in than to have to keep a separate module in ...
      (freebsd-current)
    • Re: panic: getnewvnode: free vnode isnt
      ... > Could people seeing this panic try the following patch? ... > callers of vcleanensure that the vnode is not on the free list, ... The patch hasn't stopped the panics, but I've tracked down a series of ... while the modem was plugged in. ...
      (freebsd-current)
    • Re: fs/udf: vm pages "overlap" while reading large dir [patch]
      ... Actually the patch is not entirely correct. ... reading via device vnode would work correctly. ... Hunk5 - return EOPNOTSUPP for unusual files, ...
      (freebsd-hackers)
    • Re: Freeing vnodes.
      ... On Tue, 29 Mar 2005, Jeff Roberson wrote: ... > I'll look at your patch again soon. ... You should wrap vn_fullpathwith Giant and then commit ... > vnode, or names this vnode is a source for. ...
      (freebsd-arch)