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Adjust sillyrename cleanup code to deal with the parent vnode

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already being locked by our thread. VOP_INACTIVATE() makes no
statement as to the lock state of the parent, yet this code assumed
we had it unlocked.

With this change, we let vn_lock() fail with EDEADLK if we already
have the parent locked. We then handle the rename cleanup, and on
the way out just vrele() the parent vnode, not vput() it.

Fixes a case seen by Steve Woodford at Wasabisystems dot com where
we'd panic while running a pkgsrc configure test that verified
fork() functionality. I expect the problem is a result of the recent
exit() changes and the performance of the machines he tested on.

Specifically we would crash during an nfs_remove(). As best I can
tell, when nfs_remove() tested to see if we should rename or we
should remove, v_usecount was > 1 and vattr.va_nlink was 1. Thus
we did the sillyrename in nfs_remove(). However by the time we got
down to the vput(vp), v_usecount had dropped to one and thus vput()
triggered the VOP_INACTIVATE() code path. nfs_inactive() tries to
lock the parent to undo the sillyrename, and deadlocks as we still
have it locked.
This commit is contained in:
wrstuden 2004-01-23 22:20:20 +00:00
parent 33a43be982
commit b5053f07a1
1 changed files with 12 additions and 4 deletions
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16
sys/nfs/nfs_node.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: nfs_node.c,v 1.71 2003/12/07 21:15:46 fvdl Exp $ */
/* $NetBSD: nfs_node.c,v 1.72 2004/01/23 22:20:20 wrstuden Exp $ */
/*
* Copyright (c) 1989, 1993
@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nfs_node.c,v 1.71 2003/12/07 21:15:46 fvdl Exp $");
__KERNEL_RCSID(0, "$NetBSD: nfs_node.c,v 1.72 2004/01/23 22:20:20 wrstuden Exp $");
#include "opt_nfs.h"
@ -238,6 +238,7 @@ nfs_inactive(v)
struct vnode *vp = ap->a_vp;
struct nfsmount *nmp = VFSTONFS(vp->v_mount);
boolean_t removed;
int err;
np = VTONFS(vp);
if (prtactive && vp->v_usecount != 0)
@ -257,12 +258,19 @@ nfs_inactive(v)
/*
* Remove the silly file that was rename'd earlier
*
* Just in case our thread also has the parent node locked,
* we let vn_lock() fail.
*/
vn_lock(sp->s_dvp, LK_EXCLUSIVE | LK_RETRY);
err = vn_lock(sp->s_dvp, LK_EXCLUSIVE | LK_RETRY
| LK_RECURSEFAIL);
nfs_removeit(sp);
crfree(sp->s_cred);
vput(sp->s_dvp);
if (err != EDEADLK)
vput(sp->s_dvp);
else
vrele(sp->s_dvp);
FREE(sp, M_NFSREQ);
}