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authorSunil Mushran <sunil.mushran@oracle.com>2008-12-16 15:49:22 -0800
committerMark Fasheh <mfasheh@suse.com>2009-01-05 08:40:35 -0800
commitb0d4f817ba5de8adb875ace594554a96d7737710 (patch)
tree2e64d3240d6ad879c4ffa1c01ca1696abf3bb2fb /fs/ocfs2/dlm/dlmmaster.c
parentd4f7e650e55af6b235871126f747da88600e8040 (diff)
ocfs2/dlm: Fix race in adding/removing lockres' to/from the tracking list
This patch adds a new lock, dlm->tracking_lock, to protect adding/removing lockres' to/from the dlm->tracking_list. We were previously using dlm->spinlock for the same, but that proved inadequate as we could be freeing a lockres from a context that did not hold that lock. As the new lock only protects this list, we can explicitly take it when removing the lockres from the tracking list. This bug was exposed when testing multiple processes concurrently flock() the same file. Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Diffstat (limited to 'fs/ocfs2/dlm/dlmmaster.c')
-rw-r--r--fs/ocfs2/dlm/dlmmaster.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 92fd1d7d612..cbf3abe24cd 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -505,8 +505,10 @@ void dlm_change_lockres_owner(struct dlm_ctxt *dlm,
static void dlm_lockres_release(struct kref *kref)
{
struct dlm_lock_resource *res;
+ struct dlm_ctxt *dlm;
res = container_of(kref, struct dlm_lock_resource, refs);
+ dlm = res->dlm;
/* This should not happen -- all lockres' have a name
* associated with them at init time. */
@@ -515,6 +517,7 @@ static void dlm_lockres_release(struct kref *kref)
mlog(0, "destroying lockres %.*s\n", res->lockname.len,
res->lockname.name);
+ spin_lock(&dlm->track_lock);
if (!list_empty(&res->tracking))
list_del_init(&res->tracking);
else {
@@ -522,6 +525,9 @@ static void dlm_lockres_release(struct kref *kref)
res->lockname.len, res->lockname.name);
dlm_print_one_lock_resource(res);
}
+ spin_unlock(&dlm->track_lock);
+
+ dlm_put(dlm);
if (!hlist_unhashed(&res->hash_node) ||
!list_empty(&res->granted) ||
@@ -595,6 +601,10 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
res->migration_pending = 0;
res->inflight_locks = 0;
+ /* put in dlm_lockres_release */
+ dlm_grab(dlm);
+ res->dlm = dlm;
+
kref_init(&res->refs);
/* just for consistency */