Author: rmacklem
Date: Fri Sep 10 23:49:33 2010
New Revision: 212443
URL: http://svn.freebsd.org/changeset/base/212443
Log:
This patch applies one of the two fixes suggested by
zack.kirsch at isilon.com for a race between nfsrv_freeopen()
and nfsrv_getlockfile() in the experimental NFS server that
he found during testing. Although nfsrv_freeopen() holds a
sleep lock on the lock file structure when called with
cansleep != 0, nfsrv_getlockfile() could still search the
list, once it acquired the NFSLOCKSTATE() mutex. I believe
that acquiring the mutex in nfsrv_freeopen() fixes the race.
MFC after: 2 weeks
Modified:
head/sys/fs/nfsserver/nfs_nfsdstate.c
Modified: head/sys/fs/nfsserver/nfs_nfsdstate.c
==============================================================================
--- head/sys/fs/nfsserver/nfs_nfsdstate.c Fri Sep 10 23:38:18 2010
(r212442)
+++ head/sys/fs/nfsserver/nfs_nfsdstate.c Fri Sep 10 23:49:33 2010
(r212443)
@@ -1085,8 +1085,11 @@ nfsrv_freeopen(struct nfsstate *stp, vno
* associated with the open.
* If there are locks associated with the open, the
* nfslockfile structure can be freed via nfsrv_freelockowner().
- * (That is why the call must be here instead of after the loop.)
+ * Acquire the state mutex to avoid races with calls to
+ * nfsrv_getlockfile().
*/
+ if (cansleep != 0)
+ NFSLOCKSTATE();
if (lfp != NULL && LIST_EMPTY(&lfp->lf_open) &&
LIST_EMPTY(&lfp->lf_deleg) && LIST_EMPTY(&lfp->lf_lock) &&
LIST_EMPTY(&lfp->lf_locallock) && LIST_EMPTY(&lfp->lf_rollback) &&
@@ -1096,6 +1099,8 @@ nfsrv_freeopen(struct nfsstate *stp, vno
ret = 1;
} else
ret = 0;
+ if (cansleep != 0)
+ NFSUNLOCKSTATE();
FREE((caddr_t)stp, M_NFSDSTATE);
newnfsstats.srvopens--;
nfsrv_openpluslock--;
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