From: David Teigland <teigland@redhat.com> Subject: [RHEL5 PATCH] dlm: don't accept replies to old recovery messages Date: Mon, 27 Nov 2006 12:21:08 -0600 Bugzilla: 215430 Message-Id: <20061127182108.GE18093@redhat.com> Changelog: dlm: don't accept replies to old recovery messages bz 215430 patch 2 of 2 We often abort a recovery after sending a status request to a remote node. We want to ignore any potential status reply we get from the remote node. If we get one of these unwanted replies, we've often moved on to the next recovery message and incremented the message sequence counter, so the reply will be ignored due to the seq number. In some cases, we've not moved on to the next message so the seq number of the reply we want to ignore is still correct, causing the reply to be accepted. The next recovery message will then mistake this old reply as a new one. To fix this, we add the flag RCOM_WAIT to indicate when we can accept a new reply. We clear this flag if we abort recovery while waiting for a reply. Before the flag is set again (to allow new replies) we know that any old replies will be rejected due to their sequence number. We also initialize the recovery-message sequence number to a random value when a lockspace is first created. This makes it clear when messages are being rejected from an old instance of a lockspace that has since been recreated. Index: latest/fs/dlm/rcom.c =================================================================== --- latest.orig/fs/dlm/rcom.c +++ latest/fs/dlm/rcom.c @@ -90,13 +90,28 @@ static int check_config(struct dlm_ls *l return 0; } +static void allow_sync_reply(struct dlm_ls *ls, uint64_t *new_seq) +{ + spin_lock(&ls->ls_rcom_spin); + *new_seq = ++ls->ls_rcom_seq; + set_bit(LSFL_RCOM_WAIT, &ls->ls_flags); + spin_unlock(&ls->ls_rcom_spin); +} + +static void disallow_sync_reply(struct dlm_ls *ls) +{ + spin_lock(&ls->ls_rcom_spin); + clear_bit(LSFL_RCOM_WAIT, &ls->ls_flags); + clear_bit(LSFL_RCOM_READY, &ls->ls_flags); + spin_unlock(&ls->ls_rcom_spin); +} + int dlm_rcom_status(struct dlm_ls *ls, int nodeid) { struct dlm_rcom *rc; struct dlm_mhandle *mh; int error = 0; - memset(ls->ls_recover_buf, 0, dlm_config.buffer_size); ls->ls_recover_nodeid = nodeid; if (nodeid == dlm_our_nodeid()) { @@ -108,12 +123,14 @@ int dlm_rcom_status(struct dlm_ls *ls, i error = create_rcom(ls, nodeid, DLM_RCOM_STATUS, 0, &rc, &mh); if (error) goto out; - rc->rc_id = ++ls->ls_rcom_seq; + + allow_sync_reply(ls, &rc->rc_id); + memset(ls->ls_recover_buf, 0, dlm_config.buffer_size); send_rcom(ls, mh, rc); error = dlm_wait_function(ls, &rcom_response); - clear_bit(LSFL_RCOM_READY, &ls->ls_flags); + disallow_sync_reply(ls); if (error) goto out; @@ -150,14 +167,20 @@ static void receive_rcom_status(struct d static void receive_sync_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in) { - if (rc_in->rc_id != ls->ls_rcom_seq) { - log_debug(ls, "reject old reply %d got %llx wanted %llx", - rc_in->rc_type, rc_in->rc_id, ls->ls_rcom_seq); - return; + spin_lock(&ls->ls_rcom_spin); + if (!test_bit(LSFL_RCOM_WAIT, &ls->ls_flags) || + rc_in->rc_id != ls->ls_rcom_seq) { + log_debug(ls, "reject reply %d from %d seq %llx expect %llx", + rc_in->rc_type, rc_in->rc_header.h_nodeid, + rc_in->rc_id, ls->ls_rcom_seq); + goto out; } memcpy(ls->ls_recover_buf, rc_in, rc_in->rc_header.h_length); set_bit(LSFL_RCOM_READY, &ls->ls_flags); + clear_bit(LSFL_RCOM_WAIT, &ls->ls_flags); wake_up(&ls->ls_wait_general); + out: + spin_unlock(&ls->ls_rcom_spin); } static void receive_rcom_status_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in) @@ -171,7 +194,6 @@ int dlm_rcom_names(struct dlm_ls *ls, in struct dlm_mhandle *mh; int error = 0, len = sizeof(struct dlm_rcom); - memset(ls->ls_recover_buf, 0, dlm_config.buffer_size); ls->ls_recover_nodeid = nodeid; if (nodeid == dlm_our_nodeid()) { @@ -185,12 +207,14 @@ int dlm_rcom_names(struct dlm_ls *ls, in if (error) goto out; memcpy(rc->rc_buf, last_name, last_len); - rc->rc_id = ++ls->ls_rcom_seq; + + allow_sync_reply(ls, &rc->rc_id); + memset(ls->ls_recover_buf, 0, dlm_config.buffer_size); send_rcom(ls, mh, rc); error = dlm_wait_function(ls, &rcom_response); - clear_bit(LSFL_RCOM_READY, &ls->ls_flags); + disallow_sync_reply(ls); out: return error; } Index: latest/fs/dlm/dlm_internal.h =================================================================== --- latest.orig/fs/dlm/dlm_internal.h +++ latest/fs/dlm/dlm_internal.h @@ -471,6 +471,7 @@ struct dlm_ls { char *ls_recover_buf; int ls_recover_nodeid; /* for debugging */ uint64_t ls_rcom_seq; + spinlock_t ls_rcom_spin; struct list_head ls_recover_list; spinlock_t ls_recover_list_lock; int ls_recover_list_count; @@ -488,7 +489,8 @@ struct dlm_ls { #define LSFL_RUNNING 1 #define LSFL_RECOVERY_STOP 2 #define LSFL_RCOM_READY 3 -#define LSFL_UEVENT_WAIT 4 +#define LSFL_RCOM_WAIT 4 +#define LSFL_UEVENT_WAIT 5 /* much of this is just saving user space pointers associated with the lock that we pass back to the user lib with an ast */ Index: latest/fs/dlm/lockspace.c =================================================================== --- latest.orig/fs/dlm/lockspace.c +++ latest/fs/dlm/lockspace.c @@ -473,6 +473,8 @@ static int new_lockspace(char *name, int ls->ls_recoverd_task = NULL; mutex_init(&ls->ls_recoverd_active); spin_lock_init(&ls->ls_recover_lock); + spin_lock_init(&ls->ls_rcom_spin); + get_random_bytes(&ls->ls_rcom_seq, sizeof(uint64_t)); ls->ls_recover_status = 0; ls->ls_recover_seq = 0; ls->ls_recover_args = NULL;