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authorSrinivas Eeda <srinivas.eeda@oracle.com>2010-07-19 16:04:12 -0700
committerJoel Becker <joel.becker@oracle.com>2010-08-07 10:44:40 -0700
commit7beaf243787f85a2ef9213ccf13ab4a243283fde (patch)
tree689e5a447ee2b7b83fcaccf2959ca8dd5b0fb359 /fs
parent6d98c3ccb52f692f1a60339dde7c700686a5568b (diff)
ocfs2 fix o2dlm dlm run purgelist (rev 3)
This patch fixes two problems in dlm_run_purgelist 1. If a lockres is found to be in use, dlm_run_purgelist keeps trying to purge the same lockres instead of trying the next lockres. 2. When a lockres is found unused, dlm_run_purgelist releases lockres spinlock before setting DLM_LOCK_RES_DROPPING_REF and calls dlm_purge_lockres. spinlock is reacquired but in this window lockres can get reused. This leads to BUG. This patch modifies dlm_run_purgelist to skip lockres if it's in use and purge next lockres. It also sets DLM_LOCK_RES_DROPPING_REF before releasing the lockres spinlock protecting it from getting reused. Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com> Acked-by: Sunil Mushran <sunil.mushran@oracle.com> Cc: stable@kernel.org Signed-off-by: Joel Becker <joel.becker@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/ocfs2/dlm/dlmthread.c80
1 files changed, 34 insertions, 46 deletions
diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index d4f73ca68fe5..dd78ca3f360f 100644
--- a/fs/ocfs2/dlm/dlmthread.c
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -152,45 +152,25 @@ void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
spin_unlock(&dlm->spinlock);
}
-static int dlm_purge_lockres(struct dlm_ctxt *dlm,
+static void dlm_purge_lockres(struct dlm_ctxt *dlm,
struct dlm_lock_resource *res)
{
int master;
int ret = 0;
- spin_lock(&res->spinlock);
- if (!__dlm_lockres_unused(res)) {
- mlog(0, "%s:%.*s: tried to purge but not unused\n",
- dlm->name, res->lockname.len, res->lockname.name);
- __dlm_print_one_lock_resource(res);
- spin_unlock(&res->spinlock);
- BUG();
- }
-
- if (res->state & DLM_LOCK_RES_MIGRATING) {
- mlog(0, "%s:%.*s: Delay dropref as this lockres is "
- "being remastered\n", dlm->name, res->lockname.len,
- res->lockname.name);
- /* Re-add the lockres to the end of the purge list */
- if (!list_empty(&res->purge)) {
- list_del_init(&res->purge);
- list_add_tail(&res->purge, &dlm->purge_list);
- }
- spin_unlock(&res->spinlock);
- return 0;
- }
+ assert_spin_locked(&dlm->spinlock);
+ assert_spin_locked(&res->spinlock);
master = (res->owner == dlm->node_num);
- if (!master)
- res->state |= DLM_LOCK_RES_DROPPING_REF;
- spin_unlock(&res->spinlock);
mlog(0, "purging lockres %.*s, master = %d\n", res->lockname.len,
res->lockname.name, master);
if (!master) {
+ res->state |= DLM_LOCK_RES_DROPPING_REF;
/* drop spinlock... retake below */
+ spin_unlock(&res->spinlock);
spin_unlock(&dlm->spinlock);
spin_lock(&res->spinlock);
@@ -208,31 +188,35 @@ static int dlm_purge_lockres(struct dlm_ctxt *dlm,
mlog(0, "%s:%.*s: dlm_deref_lockres returned %d\n",
dlm->name, res->lockname.len, res->lockname.name, ret);
spin_lock(&dlm->spinlock);
+ spin_lock(&res->spinlock);
}
- spin_lock(&res->spinlock);
if (!list_empty(&res->purge)) {
mlog(0, "removing lockres %.*s:%p from purgelist, "
"master = %d\n", res->lockname.len, res->lockname.name,
res, master);
list_del_init(&res->purge);
- spin_unlock(&res->spinlock);
dlm_lockres_put(res);
dlm->purge_count--;
- } else
- spin_unlock(&res->spinlock);
+ }
+
+ if (!__dlm_lockres_unused(res)) {
+ mlog(ML_ERROR, "found lockres %s:%.*s: in use after deref\n",
+ dlm->name, res->lockname.len, res->lockname.name);
+ __dlm_print_one_lock_resource(res);
+ BUG();
+ }
__dlm_unhash_lockres(res);
/* lockres is not in the hash now. drop the flag and wake up
* any processes waiting in dlm_get_lock_resource. */
if (!master) {
- spin_lock(&res->spinlock);
res->state &= ~DLM_LOCK_RES_DROPPING_REF;
spin_unlock(&res->spinlock);
wake_up(&res->wq);
- }
- return 0;
+ } else
+ spin_unlock(&res->spinlock);
}
static void dlm_run_purge_list(struct dlm_ctxt *dlm,
@@ -251,17 +235,7 @@ static void dlm_run_purge_list(struct dlm_ctxt *dlm,
lockres = list_entry(dlm->purge_list.next,
struct dlm_lock_resource, purge);
- /* Status of the lockres *might* change so double
- * check. If the lockres is unused, holding the dlm
- * spinlock will prevent people from getting and more
- * refs on it -- there's no need to keep the lockres
- * spinlock. */
spin_lock(&lockres->spinlock);
- unused = __dlm_lockres_unused(lockres);
- spin_unlock(&lockres->spinlock);
-
- if (!unused)
- continue;
purge_jiffies = lockres->last_used +
msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
@@ -273,15 +247,29 @@ static void dlm_run_purge_list(struct dlm_ctxt *dlm,
* in tail order, we can stop at the first
* unpurgable resource -- anyone added after
* him will have a greater last_used value */
+ spin_unlock(&lockres->spinlock);
break;
}
+ /* Status of the lockres *might* change so double
+ * check. If the lockres is unused, holding the dlm
+ * spinlock will prevent people from getting and more
+ * refs on it. */
+ unused = __dlm_lockres_unused(lockres);
+ if (!unused ||
+ (lockres->state & DLM_LOCK_RES_MIGRATING)) {
+ mlog(0, "lockres %s:%.*s: is in use or "
+ "being remastered, used %d, state %d\n",
+ dlm->name, lockres->lockname.len,
+ lockres->lockname.name, !unused, lockres->state);
+ list_move_tail(&dlm->purge_list, &lockres->purge);
+ spin_unlock(&lockres->spinlock);
+ continue;
+ }
+
dlm_lockres_get(lockres);
- /* This may drop and reacquire the dlm spinlock if it
- * has to do migration. */
- if (dlm_purge_lockres(dlm, lockres))
- BUG();
+ dlm_purge_lockres(dlm, lockres);
dlm_lockres_put(lockres);