[Ocfs2-devel] [PATCH 1/2] ocfs2 fix o2dlm dlm run purgelist(bug 9094491) -backport to 1.2
Wengang Wang
wen.gang.wang at oracle.com
Sun Jun 27 18:16:10 PDT 2010
On 10-06-27 11:45, Sunil Mushran wrote:
> Is it the same patch as targeted for mainline? If so, go ahead.
> If not, then please highlight the differences.
almost same as the one for mainline. just
1) make dlm_purge_lockres() static
2) removed the useless declaration of dlm_purge_lockres() from dlmcommon.h
regards,
wengang.
>
> On 06/26/2010 04:32 AM, Wengang Wang wrote:
> >There are 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 at oracle.com>
> >Signed-off-by: Sunil Mushran<sunil.mushran at oracle.com>
> >---
> > dlmcommon.h | 2 -
> > dlmthread.c | 72 +++++++++++++++++++++++++++++-------------------------------
> > 2 files changed, 35 insertions(+), 39 deletions(-)
> >
> >diff -upr ocfs2-1.2.9-7/fs/ocfs2/dlm/dlmthread.c ocfs2-1.2.9-8/fs/ocfs2/dlm/dlmthread.c
> >--- ocfs2-1.2.9-7/fs/ocfs2/dlm/dlmthread.c 2010-06-26 14:40:32.000000000 +0800
> >+++ ocfs2-1.2.9-8/fs/ocfs2/dlm/dlmthread.c 2010-06-26 18:44:14.000000000 +0800
> >@@ -156,29 +156,23 @@ void dlm_lockres_calc_usage(struct dlm_c
> > spin_unlock(&dlm->spinlock);
> > }
> >
> >-int dlm_purge_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
> >+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)) {
> >- __dlm_print_one_lock_resource(res);
> >- spin_unlock(&res->spinlock);
> >- mlog(0, "%s:%.*s: tried to purge but not unused\n",
> >- dlm->name, res->lockname.len, res->lockname.name);
> >- return -ENOTEMPTY;
> >- }
> >+ 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);
> >@@ -196,31 +190,35 @@ int dlm_purge_lockres(struct dlm_ctxt *d
> > 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,
> >@@ -239,18 +237,6 @@ static void dlm_run_purge_list(struct dl
> > 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);
> >
> >@@ -261,16 +247,28 @@ static void dlm_run_purge_list(struct dl
> > * 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;
> > }
> >
> >- 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();
> >+ /* 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\n", dlm->name,
> >+ lockres->lockname.len, lockres->lockname.name);
> >+ list_move_tail(&dlm->purge_list,&lockres->purge);
> >+ spin_unlock(&lockres->spinlock);
> >+ continue;
> >+ }
> >
> >+ dlm_lockres_get(lockres);
> >+ dlm_purge_lockres(dlm, lockres);
> > dlm_lockres_put(lockres);
> >
> > /* Avoid adding any scheduling latencies */
> >diff -urp ocfs2-1.2.9-7/fs/ocfs2/dlm/dlmcommon.h ocfs2-1.2.9-8/fs/ocfs2/dlm/dlmcommon.h
> >--- ocfs2-1.2.9-7/fs/ocfs2/dlm/dlmcommon.h 2010-06-26 14:40:32.000000000 +0800
> >+++ ocfs2-1.2.9-8/fs/ocfs2/dlm/dlmcommon.h 2010-06-26 18:57:19.000000000 +0800
> >@@ -753,8 +753,6 @@ void __dlm_lockres_calc_usage(struct dlm
> > struct dlm_lock_resource *res);
> > void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
> > struct dlm_lock_resource *res);
> >-int dlm_purge_lockres(struct dlm_ctxt *dlm,
> >- struct dlm_lock_resource *lockres);
> > void dlm_lockres_get(struct dlm_lock_resource *res);
> > void dlm_lockres_put(struct dlm_lock_resource *res);
> > void __dlm_unhash_lockres(struct dlm_lock_resource *res);
> >
> >_______________________________________________
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> >Ocfs2-devel at oss.oracle.com
> >http://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
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