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[DLM] block dlm_recv in recovery transition

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Introduce a per-lockspace rwsem that's held in read mode by dlm_recv
threads while working in the dlm.  This allows dlm_recv activity to be
suspended when the lockspace transitions to, from and between recovery
cycles.

The specific bug prompting this change is one where an in-progress
recovery cycle is aborted by a new recovery cycle.  While dlm_recv was
processing a recovery message, the recovery cycle was aborted and
dlm_recoverd began cleaning up.  dlm_recv decremented recover_locks_count
on an rsb after dlm_recoverd had reset it to zero.  This is fixed by
suspending dlm_recv (taking write lock on the rwsem) before aborting the
current recovery.

The transitions to/from normal and recovery modes are simplified by using
this new ability to block dlm_recv.  The switch from normal to recovery
mode means dlm_recv goes from processing locking messages, to saving them
for later, and vice versa.  Races are avoided by blocking dlm_recv when
setting the flag that switches between modes.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
David Teigland
2007-09-27 15:53:38 -05:00
committed by Steven Whitehouse
parent b434eda6fd
commit c36258b592
11 changed files with 161 additions and 152 deletions
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136
fs/dlm/lock.c
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@@ -3638,55 +3638,8 @@ static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
dlm_put_lkb(lkb);
}
int dlm_receive_message(struct dlm_header *hd, int nodeid, int recovery)
static void _receive_message(struct dlm_ls *ls, struct dlm_message *ms)
{
struct dlm_message *ms = (struct dlm_message *) hd;
struct dlm_ls *ls;
int error = 0;
if (!recovery)
dlm_message_in(ms);
ls = dlm_find_lockspace_global(hd->h_lockspace);
if (!ls) {
log_print("drop message %d from %d for unknown lockspace %d",
ms->m_type, nodeid, hd->h_lockspace);
return -EINVAL;
}
/* recovery may have just ended leaving a bunch of backed-up requests
in the requestqueue; wait while dlm_recoverd clears them */
if (!recovery)
dlm_wait_requestqueue(ls);
/* recovery may have just started while there were a bunch of
in-flight requests -- save them in requestqueue to be processed
after recovery. we can't let dlm_recvd block on the recovery
lock. if dlm_recoverd is calling this function to clear the
requestqueue, it needs to be interrupted (-EINTR) if another
recovery operation is starting. */
while (1) {
if (dlm_locking_stopped(ls)) {
if (recovery) {
error = -EINTR;
goto out;
}
error = dlm_add_requestqueue(ls, nodeid, hd);
if (error == -EAGAIN)
continue;
else {
error = -EINTR;
goto out;
}
}
if (dlm_lock_recovery_try(ls))
break;
schedule();
}
switch (ms->m_type) {
/* messages sent to a master node */
@@ -3761,17 +3714,90 @@ int dlm_receive_message(struct dlm_header *hd, int nodeid, int recovery)
log_error(ls, "unknown message type %d", ms->m_type);
}
dlm_unlock_recovery(ls);
out:
dlm_put_lockspace(ls);
dlm_astd_wake();
return error;
}
/* If the lockspace is in recovery mode (locking stopped), then normal
messages are saved on the requestqueue for processing after recovery is
done. When not in recovery mode, we wait for dlm_recoverd to drain saved
messages off the requestqueue before we process new ones. This occurs right
after recovery completes when we transition from saving all messages on
requestqueue, to processing all the saved messages, to processing new
messages as they arrive. */
/*
* Recovery related
*/
static void dlm_receive_message(struct dlm_ls *ls, struct dlm_message *ms,
int nodeid)
{
if (dlm_locking_stopped(ls)) {
dlm_add_requestqueue(ls, nodeid, (struct dlm_header *) ms);
} else {
dlm_wait_requestqueue(ls);
_receive_message(ls, ms);
}
}
/* This is called by dlm_recoverd to process messages that were saved on
the requestqueue. */
void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms)
{
_receive_message(ls, ms);
}
/* This is called by the midcomms layer when something is received for
the lockspace. It could be either a MSG (normal message sent as part of
standard locking activity) or an RCOM (recovery message sent as part of
lockspace recovery). */
void dlm_receive_buffer(struct dlm_header *hd, int nodeid)
{
struct dlm_message *ms = (struct dlm_message *) hd;
struct dlm_rcom *rc = (struct dlm_rcom *) hd;
struct dlm_ls *ls;
int type = 0;
switch (hd->h_cmd) {
case DLM_MSG:
dlm_message_in(ms);
type = ms->m_type;
break;
case DLM_RCOM:
dlm_rcom_in(rc);
type = rc->rc_type;
break;
default:
log_print("invalid h_cmd %d from %u", hd->h_cmd, nodeid);
return;
}
if (hd->h_nodeid != nodeid) {
log_print("invalid h_nodeid %d from %d lockspace %x",
hd->h_nodeid, nodeid, hd->h_lockspace);
return;
}
ls = dlm_find_lockspace_global(hd->h_lockspace);
if (!ls) {
log_print("invalid h_lockspace %x from %d cmd %d type %d",
hd->h_lockspace, nodeid, hd->h_cmd, type);
if (hd->h_cmd == DLM_RCOM && type == DLM_RCOM_STATUS)
dlm_send_ls_not_ready(nodeid, rc);
return;
}
/* this rwsem allows dlm_ls_stop() to wait for all dlm_recv threads to
be inactive (in this ls) before transitioning to recovery mode */
down_read(&ls->ls_recv_active);
if (hd->h_cmd == DLM_MSG)
dlm_receive_message(ls, ms, nodeid);
else
dlm_receive_rcom(ls, rc, nodeid);
up_read(&ls->ls_recv_active);
dlm_put_lockspace(ls);
}
static void recover_convert_waiter(struct dlm_ls *ls, struct dlm_lkb *lkb)
{