[Ocfs2-devel] [PATCH 1/2] ocfs2 fix o2dlm dlm run purgelist(bug 9094491) -backport to 1.2
Sunil Mushran
sunil.mushran at oracle.com
Sun Jun 27 11:45:51 PDT 2010
Is it the same patch as targeted for mainline? If so, go ahead.
If not, then please highlight the differences.
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);
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
More information about the Ocfs2-devel
mailing list