fs: dlm: remove ls_remove_wait waitqueue
This patch removes the ls_remove_wait waitqueue handling. The current handling tries to wait before a lookup is send out for a identically resource name which is going to be removed. Hereby the remove message should be send out before the new lookup message. The reason is that after a lookup request and response will actually use the specific remote rsb. A followed remove message would delete the rsb on the remote side but it's still being used. To reach a similar behaviour we simple send the remove message out while the rsb lookup lock is held and the rsb is removed from the toss list. Other find_rsb() calls would never have the change to get a rsb back to live while a remove message will be send out (without holding the lock). This behaviour requires a non-sleepable context which should be provided now and might be the reason why it was not implemented so in the first place. Signed-off-by: Alexander Aring <aahringo@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com>
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@ -592,11 +592,7 @@ struct dlm_ls {
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int ls_new_rsb_count;
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struct list_head ls_new_rsb; /* new rsb structs */
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spinlock_t ls_remove_spin;
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wait_queue_head_t ls_remove_wait;
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char ls_remove_name[DLM_RESNAME_MAXLEN+1];
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char *ls_remove_names[DLM_REMOVE_NAMES_MAX];
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int ls_remove_len;
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int ls_remove_lens[DLM_REMOVE_NAMES_MAX];
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struct list_head ls_nodes; /* current nodes in ls */
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@ -1589,37 +1589,6 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms)
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return error;
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}
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/* If there's an rsb for the same resource being removed, ensure
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* that the remove message is sent before the new lookup message.
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*/
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#define DLM_WAIT_PENDING_COND(ls, r) \
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(ls->ls_remove_len && \
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!rsb_cmp(r, ls->ls_remove_name, \
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ls->ls_remove_len))
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static void wait_pending_remove(struct dlm_rsb *r)
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{
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struct dlm_ls *ls = r->res_ls;
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restart:
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spin_lock(&ls->ls_remove_spin);
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if (DLM_WAIT_PENDING_COND(ls, r)) {
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log_debug(ls, "delay lookup for remove dir %d %s",
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r->res_dir_nodeid, r->res_name);
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spin_unlock(&ls->ls_remove_spin);
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wait_event(ls->ls_remove_wait, !DLM_WAIT_PENDING_COND(ls, r));
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goto restart;
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}
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spin_unlock(&ls->ls_remove_spin);
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}
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/*
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* ls_remove_spin protects ls_remove_name and ls_remove_len which are
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* read by other threads in wait_pending_remove. ls_remove_names
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* and ls_remove_lens are only used by the scan thread, so they do
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* not need protection.
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*/
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static void shrink_bucket(struct dlm_ls *ls, int b)
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{
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struct rb_node *n, *next;
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@ -1701,11 +1670,6 @@ static void shrink_bucket(struct dlm_ls *ls, int b)
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* list and sending the removal. Keeping this gap small is
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* important to keep us (the master node) from being out of sync
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* with the remote dir node for very long.
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*
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* From the time the rsb is removed from toss until just after
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* send_remove, the rsb name is saved in ls_remove_name. A new
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* lookup checks this to ensure that a new lookup message for the
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* same resource name is not sent just before the remove message.
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*/
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for (i = 0; i < remote_count; i++) {
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@ -1752,22 +1716,8 @@ static void shrink_bucket(struct dlm_ls *ls, int b)
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}
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rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss);
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/* block lookup of same name until we've sent remove */
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spin_lock(&ls->ls_remove_spin);
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ls->ls_remove_len = len;
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memcpy(ls->ls_remove_name, name, DLM_RESNAME_MAXLEN);
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spin_unlock(&ls->ls_remove_spin);
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spin_unlock(&ls->ls_rsbtbl[b].lock);
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send_remove(r);
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/* allow lookup of name again */
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spin_lock(&ls->ls_remove_spin);
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ls->ls_remove_len = 0;
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memset(ls->ls_remove_name, 0, DLM_RESNAME_MAXLEN);
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spin_unlock(&ls->ls_remove_spin);
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wake_up(&ls->ls_remove_wait);
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spin_unlock(&ls->ls_rsbtbl[b].lock);
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dlm_free_rsb(r);
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}
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@ -2718,8 +2668,6 @@ static int set_master(struct dlm_rsb *r, struct dlm_lkb *lkb)
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return 0;
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}
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wait_pending_remove(r);
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r->res_first_lkid = lkb->lkb_id;
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send_lookup(r, lkb);
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return 1;
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@ -3813,7 +3761,7 @@ static int send_remove(struct dlm_rsb *r)
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to_nodeid = dlm_dir_nodeid(r);
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error = create_message(r, NULL, to_nodeid, DLM_MSG_REMOVE, &ms, &mh,
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GFP_NOFS);
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GFP_ATOMIC);
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if (error)
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goto out;
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@ -524,9 +524,6 @@ static int new_lockspace(const char *name, const char *cluster,
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spin_lock_init(&ls->ls_rsbtbl[i].lock);
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}
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spin_lock_init(&ls->ls_remove_spin);
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init_waitqueue_head(&ls->ls_remove_wait);
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for (i = 0; i < DLM_REMOVE_NAMES_MAX; i++) {
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ls->ls_remove_names[i] = kzalloc(DLM_RESNAME_MAXLEN+1,
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GFP_KERNEL);
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