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<[email protected]> > Signed-off-by: Sunil Mushran<[email protected]> > --- > 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 > [email protected] > http://oss.oracle.com/mailman/listinfo/ocfs2-devel > _______________________________________________ Ocfs2-devel mailing list [email protected] http://oss.oracle.com/mailman/listinfo/ocfs2-devel
