Junxiao Bi
2015-Sep-20 07:20 UTC
[Ocfs2-devel] [PATCH v2] ocfs2/dlm: fix race between convert and recovery
Reviewed-by: Junxiao Bi <junxiao.bi at oracle.com>> ? 2015?9?18????7:25?Joseph Qi <joseph.qi at huawei.com> ??? > > There is a race window between dlmconvert_remote and > dlm_move_lockres_to_recovery_list, which will cause a lock with > OCFS2_LOCK_BUSY in grant list, thus system hangs. > > dlmconvert_remote > { > spin_lock(&res->spinlock); > list_move_tail(&lock->list, &res->converting); > lock->convert_pending = 1; > spin_unlock(&res->spinlock); > > status = dlm_send_remote_convert_request(); >>>>>>> race window, master has queued ast and return DLM_NORMAL, > and then down before sending ast. > this node detects master down and calls > dlm_move_lockres_to_recovery_list, which will revert the > lock to grant list. > Then OCFS2_LOCK_BUSY won't be cleared as new master won't > send ast any more because it thinks already be authorized. > > spin_lock(&res->spinlock); > lock->convert_pending = 0; > if (status != DLM_NORMAL) > dlm_revert_pending_convert(res, lock); > spin_unlock(&res->spinlock); > } > > In this case, just leave it in convert list and new master will take care > of it after recovery. And if convert request returns other than > DLM_NORMAL, convert thread will do the revert itself. So remove the > revert logic in dlm_move_lockres_to_recovery_list. > > changelog since v1: > Clean up convert_pending since it is now useless. > > Signed-off-by: Joseph Qi <joseph.qi at huawei.com> > Reported-by: Yiwen Jiang <jiangyiwen at huawei.com> > Cc: <stable at vger.kernel.org> > --- > fs/ocfs2/dlm/dlmcommon.h | 1 - > fs/ocfs2/dlm/dlmconvert.c | 2 -- > fs/ocfs2/dlm/dlmdebug.c | 7 +++---- > fs/ocfs2/dlm/dlmlock.c | 1 - > fs/ocfs2/dlm/dlmrecovery.c | 10 +--------- > 5 files changed, 4 insertions(+), 17 deletions(-) > > diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h > index e88ccf8..25853d7 100644 > --- a/fs/ocfs2/dlm/dlmcommon.h > +++ b/fs/ocfs2/dlm/dlmcommon.h > @@ -369,7 +369,6 @@ struct dlm_lock > struct dlm_lockstatus *lksb; > unsigned ast_pending:1, > bast_pending:1, > - convert_pending:1, > lock_pending:1, > cancel_pending:1, > unlock_pending:1, > diff --git a/fs/ocfs2/dlm/dlmconvert.c b/fs/ocfs2/dlm/dlmconvert.c > index e36d63f..82ba8d5 100644 > --- a/fs/ocfs2/dlm/dlmconvert.c > +++ b/fs/ocfs2/dlm/dlmconvert.c > @@ -291,7 +291,6 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm, > /* move lock to local convert queue */ > /* do not alter lock refcount. switching lists. */ > list_move_tail(&lock->list, &res->converting); > - lock->convert_pending = 1; > lock->ml.convert_type = type; > > if (flags & LKM_VALBLK) { > @@ -315,7 +314,6 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm, > > spin_lock(&res->spinlock); > res->state &= ~DLM_LOCK_RES_IN_PROGRESS; > - lock->convert_pending = 0; > /* if it failed, move it back to granted queue */ > if (status != DLM_NORMAL) { > if (status != DLM_NOTQUEUED) > diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c > index 8251360..710e94c 100644 > --- a/fs/ocfs2/dlm/dlmdebug.c > +++ b/fs/ocfs2/dlm/dlmdebug.c > @@ -77,7 +77,7 @@ static void __dlm_print_lock(struct dlm_lock *lock) > > printk(" type=%d, conv=%d, node=%u, cookie=%u:%llu, " > "ref=%u, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c), " > - "pending=(conv=%c,lock=%c,cancel=%c,unlock=%c)\n", > + "pending=(lock=%c,cancel=%c,unlock=%c)\n", > lock->ml.type, lock->ml.convert_type, lock->ml.node, > dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)), > dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)), > @@ -86,7 +86,6 @@ static void __dlm_print_lock(struct dlm_lock *lock) > (lock->ast_pending ? 'y' : 'n'), > (list_empty(&lock->bast_list) ? 'y' : 'n'), > (lock->bast_pending ? 'y' : 'n'), > - (lock->convert_pending ? 'y' : 'n'), > (lock->lock_pending ? 'y' : 'n'), > (lock->cancel_pending ? 'y' : 'n'), > (lock->unlock_pending ? 'y' : 'n')); > @@ -502,7 +501,7 @@ static int dump_lock(struct dlm_lock *lock, int list_type, char *buf, int len) > > #define DEBUG_LOCK_VERSION 1 > spin_lock(&lock->spinlock); > - out = snprintf(buf, len, "LOCK:%d,%d,%d,%d,%d,%d:%lld,%d,%d,%d,%d,%d," > + out = snprintf(buf, len, "LOCK:%d,%d,%d,%d,%d,%d:%lld,%d,%d,%d,%d," > "%d,%d,%d,%d\n", > DEBUG_LOCK_VERSION, > list_type, lock->ml.type, lock->ml.convert_type, > @@ -512,7 +511,7 @@ static int dump_lock(struct dlm_lock *lock, int list_type, char *buf, int len) > !list_empty(&lock->ast_list), > !list_empty(&lock->bast_list), > lock->ast_pending, lock->bast_pending, > - lock->convert_pending, lock->lock_pending, > + lock->lock_pending, > lock->cancel_pending, lock->unlock_pending, > atomic_read(&lock->lock_refs.refcount)); > spin_unlock(&lock->spinlock); > diff --git a/fs/ocfs2/dlm/dlmlock.c b/fs/ocfs2/dlm/dlmlock.c > index 66c2a49..857dd15 100644 > --- a/fs/ocfs2/dlm/dlmlock.c > +++ b/fs/ocfs2/dlm/dlmlock.c > @@ -411,7 +411,6 @@ static void dlm_init_lock(struct dlm_lock *newlock, int type, > newlock->ml.cookie = cpu_to_be64(cookie); > newlock->ast_pending = 0; > newlock->bast_pending = 0; > - newlock->convert_pending = 0; > newlock->lock_pending = 0; > newlock->unlock_pending = 0; > newlock->cancel_pending = 0; > diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c > index 3d90ad7..2402ef7 100644 > --- a/fs/ocfs2/dlm/dlmrecovery.c > +++ b/fs/ocfs2/dlm/dlmrecovery.c > @@ -2062,15 +2062,7 @@ void dlm_move_lockres_to_recovery_list(struct dlm_ctxt *dlm, > queue = dlm_list_idx_to_ptr(res, i); > list_for_each_entry_safe(lock, next, queue, list) { > dlm_lock_get(lock); > - if (lock->convert_pending) { > - /* move converting lock back to granted */ > - BUG_ON(i != DLM_CONVERTING_LIST); > - mlog(0, "node died with convert pending " > - "on %.*s. move back to granted list.\n", > - res->lockname.len, res->lockname.name); > - dlm_revert_pending_convert(res, lock); > - lock->convert_pending = 0; > - } else if (lock->lock_pending) { > + if (lock->lock_pending) { > /* remove pending lock requests completely */ > BUG_ON(i != DLM_BLOCKED_LIST); > mlog(0, "node died with lock pending " > -- > 1.8.4.3 > >
Joseph Qi
2015-Sep-21 09:23 UTC
[Ocfs2-devel] [PATCH v2] ocfs2/dlm: fix race between convert and recovery
Hi Junxiao, This solution may have problem in the following scenario: Consider dlm_send_remote_convert_request has taken too much time, and dlm_move_lockres_to_recovery_list runs first and new master will see this node is currently in convert list after recovery. Then dlm_send_remote_convert_request returns other than DLM_NORMAL and it will revert it to grant list, then retry convert. This will makes this node and master inconsistent. I will try to find another solution to resolve the race issue. On 2015/9/20 15:20, Junxiao Bi wrote:> Reviewed-by: Junxiao Bi <junxiao.bi at oracle.com> > >> > ? 2015?9?18????7:25?Joseph Qi <joseph.qi at huawei.com> ??? >> > >> > There is a race window between dlmconvert_remote and >> > dlm_move_lockres_to_recovery_list, which will cause a lock with >> > OCFS2_LOCK_BUSY in grant list, thus system hangs. >> > >> > dlmconvert_remote >> > { >> > spin_lock(&res->spinlock); >> > list_move_tail(&lock->list, &res->converting); >> > lock->convert_pending = 1; >> > spin_unlock(&res->spinlock); >> > >> > status = dlm_send_remote_convert_request(); >>>>>>>> >>>>>>> race window, master has queued ast and return DLM_NORMAL, >> > and then down before sending ast. >> > this node detects master down and calls >> > dlm_move_lockres_to_recovery_list, which will revert the >> > lock to grant list. >> > Then OCFS2_LOCK_BUSY won't be cleared as new master won't >> > send ast any more because it thinks already be authorized. >> > >> > spin_lock(&res->spinlock); >> > lock->convert_pending = 0; >> > if (status != DLM_NORMAL) >> > dlm_revert_pending_convert(res, lock); >> > spin_unlock(&res->spinlock); >> > } >> > >> > In this case, just leave it in convert list and new master will take care >> > of it after recovery. And if convert request returns other than >> > DLM_NORMAL, convert thread will do the revert itself. So remove the >> > revert logic in dlm_move_lockres_to_recovery_list. >> > >> > changelog since v1: >> > Clean up convert_pending since it is now useless.