22 messages in org.freebsd.freebsd-archFreeing vnodes.| From | Sent On | Attachments |
|---|---|---|
| Jeff Roberson | Mar 14, 2005 6:38 pm | |
| Stephan Uphoff | Mar 14, 2005 7:15 pm | |
| Jeff Roberson | Mar 14, 2005 9:39 pm | |
| Matthew Dillon | Mar 14, 2005 11:29 pm | |
| Jeff Roberson | Mar 15, 2005 12:57 am | |
| Stephan Uphoff | Mar 15, 2005 6:29 am | |
| Matthew Dillon | Mar 15, 2005 11:11 am | |
| Jeff Roberson | Mar 15, 2005 5:10 pm | |
| Don Lewis | Mar 15, 2005 7:33 pm | |
| Peter Jeremy | Mar 16, 2005 12:41 am | |
| Poul-Henning Kamp | Mar 16, 2005 12:50 am | |
| Don Lewis | Mar 16, 2005 12:58 am | |
| Alexander Leidinger | Mar 16, 2005 1:23 am | |
| Stephan Uphoff | Mar 27, 2005 8:20 pm | |
| Jeff Roberson | Mar 28, 2005 8:11 pm | |
| David Schultz | Mar 28, 2005 8:49 pm | |
| Jeff Roberson | Mar 28, 2005 9:52 pm | |
| Jeff Roberson | Mar 28, 2005 9:55 pm | |
| David Schultz | Mar 28, 2005 11:09 pm | |
| Jeff Roberson | Mar 29, 2005 12:05 am | |
| Jeff Roberson | Mar 29, 2005 5:58 am | |
| David Schultz | Mar 29, 2005 6:19 am |
| Subject: | Freeing vnodes. | |
|---|---|---|
| From: | Jeff Roberson (jrob...@chesapeake.net) | |
| Date: | Mar 28, 2005 9:55:26 pm | |
| List: | org.freebsd.freebsd-arch | |
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?
Index: vfs_cache.c =================================================================== RCS file: /home/ncvs/src/sys/kern/vfs_cache.c,v retrieving revision 1.93 diff -u -r1.93 vfs_cache.c --- vfs_cache.c 28 Mar 2005 13:29:48 -0000 1.93 +++ vfs_cache.c 29 Mar 2005 05:48:40 -0000 @@ -553,22 +553,30 @@ * XXX: by incrementing each vnodes v_id individually instead of * XXX: using the global v_id. */ - -/* - * XXX This is sometimes called when a vnode may still be re-used, in which - * case v_dd may be invalid. Need to look this up. - */ void cache_purge(vp) struct vnode *vp; { + struct namecache *ncp; static u_long nextid;
CACHE_LOCK(); while (!LIST_EMPTY(&vp->v_cache_src)) cache_zap(LIST_FIRST(&vp->v_cache_src)); - while (!TAILQ_EMPTY(&vp->v_cache_dst)) - cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); + while (!TAILQ_EMPTY(&vp->v_cache_dst)) { + struct vnode *cvp; + + ncp = TAILQ_FIRST(&vp->v_cache_dst); + /* + * We must reset v_dd of any children so they don't continue + * to point to us. + */ + if ((cvp = ncp->nc_vp) && cvp->v_dd == vp) { + cvp->v_dd = cvp; + cvp->v_ddid = 0; + } + cache_zap(ncp); + }
do nextid++;
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