From 3872f87b09e2f274ecf477895f9d1f9b9bdcf04b Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Thu, 27 Oct 2022 16:45:23 -0400 Subject: [PATCH] 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 Signed-off-by: David Teigland --- fs/dlm/dlm_internal.h | 4 ---- fs/dlm/lock.c | 56 ++------------------------------------------------- fs/dlm/lockspace.c | 3 --- 3 files changed, 2 insertions(+), 61 deletions(-) diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h index 69e3928..6318e0f 100644 --- a/fs/dlm/dlm_internal.h +++ b/fs/dlm/dlm_internal.h @@ -592,11 +592,7 @@ struct dlm_ls { int ls_new_rsb_count; struct list_head ls_new_rsb; /* new rsb structs */ - spinlock_t ls_remove_spin; - wait_queue_head_t ls_remove_wait; - char ls_remove_name[DLM_RESNAME_MAXLEN+1]; char *ls_remove_names[DLM_REMOVE_NAMES_MAX]; - int ls_remove_len; int ls_remove_lens[DLM_REMOVE_NAMES_MAX]; struct list_head ls_nodes; /* current nodes in ls */ diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c index a2930e3..e1adfa5 100644 --- a/fs/dlm/lock.c +++ b/fs/dlm/lock.c @@ -1589,37 +1589,6 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms) return error; } -/* If there's an rsb for the same resource being removed, ensure - * that the remove message is sent before the new lookup message. - */ - -#define DLM_WAIT_PENDING_COND(ls, r) \ - (ls->ls_remove_len && \ - !rsb_cmp(r, ls->ls_remove_name, \ - ls->ls_remove_len)) - -static void wait_pending_remove(struct dlm_rsb *r) -{ - struct dlm_ls *ls = r->res_ls; - restart: - spin_lock(&ls->ls_remove_spin); - if (DLM_WAIT_PENDING_COND(ls, r)) { - log_debug(ls, "delay lookup for remove dir %d %s", - r->res_dir_nodeid, r->res_name); - spin_unlock(&ls->ls_remove_spin); - wait_event(ls->ls_remove_wait, !DLM_WAIT_PENDING_COND(ls, r)); - goto restart; - } - spin_unlock(&ls->ls_remove_spin); -} - -/* - * ls_remove_spin protects ls_remove_name and ls_remove_len which are - * read by other threads in wait_pending_remove. ls_remove_names - * and ls_remove_lens are only used by the scan thread, so they do - * not need protection. - */ - static void shrink_bucket(struct dlm_ls *ls, int b) { struct rb_node *n, *next; @@ -1701,11 +1670,6 @@ static void shrink_bucket(struct dlm_ls *ls, int b) * list and sending the removal. Keeping this gap small is * important to keep us (the master node) from being out of sync * with the remote dir node for very long. - * - * From the time the rsb is removed from toss until just after - * send_remove, the rsb name is saved in ls_remove_name. A new - * lookup checks this to ensure that a new lookup message for the - * same resource name is not sent just before the remove message. */ for (i = 0; i < remote_count; i++) { @@ -1752,22 +1716,8 @@ static void shrink_bucket(struct dlm_ls *ls, int b) } rb_erase(&r->res_hashnode, &ls->ls_rsbtbl[b].toss); - - /* block lookup of same name until we've sent remove */ - spin_lock(&ls->ls_remove_spin); - ls->ls_remove_len = len; - memcpy(ls->ls_remove_name, name, DLM_RESNAME_MAXLEN); - spin_unlock(&ls->ls_remove_spin); - spin_unlock(&ls->ls_rsbtbl[b].lock); - send_remove(r); - - /* allow lookup of name again */ - spin_lock(&ls->ls_remove_spin); - ls->ls_remove_len = 0; - memset(ls->ls_remove_name, 0, DLM_RESNAME_MAXLEN); - spin_unlock(&ls->ls_remove_spin); - wake_up(&ls->ls_remove_wait); + spin_unlock(&ls->ls_rsbtbl[b].lock); dlm_free_rsb(r); } @@ -2718,8 +2668,6 @@ static int set_master(struct dlm_rsb *r, struct dlm_lkb *lkb) return 0; } - wait_pending_remove(r); - r->res_first_lkid = lkb->lkb_id; send_lookup(r, lkb); return 1; @@ -3813,7 +3761,7 @@ static int send_remove(struct dlm_rsb *r) to_nodeid = dlm_dir_nodeid(r); error = create_message(r, NULL, to_nodeid, DLM_MSG_REMOVE, &ms, &mh, - GFP_NOFS); + GFP_ATOMIC); if (error) goto out; diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c index 4965737..e713588 100644 --- a/fs/dlm/lockspace.c +++ b/fs/dlm/lockspace.c @@ -524,9 +524,6 @@ static int new_lockspace(const char *name, const char *cluster, spin_lock_init(&ls->ls_rsbtbl[i].lock); } - spin_lock_init(&ls->ls_remove_spin); - init_waitqueue_head(&ls->ls_remove_wait); - for (i = 0; i < DLM_REMOVE_NAMES_MAX; i++) { ls->ls_remove_names[i] = kzalloc(DLM_RESNAME_MAXLEN+1, GFP_KERNEL); -- 2.7.4