1 files changed, 271 insertions, 0 deletions
diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
new file mode 100644
index 0000000000..1f2f70a1b8
--- /dev/null
+++ b/fs/dlm/ast.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2010 Red Hat, Inc.  All rights reserved.
+**
+**
+*******************************************************************************
+******************************************************************************/
+
+#include <trace/events/dlm.h>
+
+#include "dlm_internal.h"
+#include "memory.h"
+#include "lock.h"
+#include "user.h"
+#include "ast.h"
+
+void dlm_release_callback(struct kref *ref)
+{
+	struct dlm_callback *cb = container_of(ref, struct dlm_callback, ref);
+
+	dlm_free_cb(cb);
+}
+
+void dlm_callback_set_last_ptr(struct dlm_callback **from,
+			       struct dlm_callback *to)
+{
+	if (*from)
+		kref_put(&(*from)->ref, dlm_release_callback);
+
+	if (to)
+		kref_get(&to->ref);
+
+	*from = to;
+}
+
+int dlm_enqueue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
+			     int status, uint32_t sbflags)
+{
+	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
+	int rv = DLM_ENQUEUE_CALLBACK_SUCCESS;
+	struct dlm_callback *cb;
+	int prev_mode;
+
+	if (flags & DLM_CB_BAST) {
+		/* if cb is a bast, it should be skipped if the blocking mode is
+		 * compatible with the last granted mode
+		 */
+		if (lkb->lkb_last_cast) {
+			if (dlm_modes_compat(mode, lkb->lkb_last_cast->mode)) {
+				log_debug(ls, "skip %x bast mode %d for cast mode %d",
+					  lkb->lkb_id, mode,
+					  lkb->lkb_last_cast->mode);
+				goto out;
+			}
+		}
+
+		/*
+		 * Suppress some redundant basts here, do more on removal.
+		 * Don't even add a bast if the callback just before it
+		 * is a bast for the same mode or a more restrictive mode.
+		 * (the addional > PR check is needed for PR/CW inversion)
+		 */
+		if (lkb->lkb_last_cb && lkb->lkb_last_cb->flags & DLM_CB_BAST) {
+			prev_mode = lkb->lkb_last_cb->mode;
+
+			if ((prev_mode == mode) ||
+			    (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
+				log_debug(ls, "skip %x add bast mode %d for bast mode %d",
+					  lkb->lkb_id, mode, prev_mode);
+				goto out;
+			}
+		}
+	}
+
+	cb = dlm_allocate_cb();
+	if (!cb) {
+		rv = DLM_ENQUEUE_CALLBACK_FAILURE;
+		goto out;
+	}
+
+	cb->flags = flags;
+	cb->mode = mode;
+	cb->sb_status = status;
+	cb->sb_flags = (sbflags & 0x000000FF);
+	kref_init(&cb->ref);
+	if (!test_and_set_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags))
+		rv = DLM_ENQUEUE_CALLBACK_NEED_SCHED;
+
+	list_add_tail(&cb->list, &lkb->lkb_callbacks);
+
+	if (flags & DLM_CB_CAST)
+		dlm_callback_set_last_ptr(&lkb->lkb_last_cast, cb);
+
+	dlm_callback_set_last_ptr(&lkb->lkb_last_cb, cb);
+
+ out:
+	return rv;
+}
+
+int dlm_dequeue_lkb_callback(struct dlm_lkb *lkb, struct dlm_callback **cb)
+{
+	/* oldest undelivered cb is callbacks first entry */
+	*cb = list_first_entry_or_null(&lkb->lkb_callbacks,
+				       struct dlm_callback, list);
+	if (!*cb)
+		return DLM_DEQUEUE_CALLBACK_EMPTY;
+
+	/* remove it from callbacks so shift others down */
+	list_del(&(*cb)->list);
+	if (list_empty(&lkb->lkb_callbacks))
+		return DLM_DEQUEUE_CALLBACK_LAST;
+
+	return DLM_DEQUEUE_CALLBACK_SUCCESS;
+}
+
+void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
+		uint32_t sbflags)
+{
+	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
+	int rv;
+
+	if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
+		dlm_user_add_ast(lkb, flags, mode, status, sbflags);
+		return;
+	}
+
+	spin_lock(&lkb->lkb_cb_lock);
+	rv = dlm_enqueue_lkb_callback(lkb, flags, mode, status, sbflags);
+	switch (rv) {
+	case DLM_ENQUEUE_CALLBACK_NEED_SCHED:
+		kref_get(&lkb->lkb_ref);
+
+		spin_lock(&ls->ls_cb_lock);
+		if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
+			list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
+		} else {
+			queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
+		}
+		spin_unlock(&ls->ls_cb_lock);
+		break;
+	case DLM_ENQUEUE_CALLBACK_FAILURE:
+		WARN_ON_ONCE(1);
+		break;
+	case DLM_ENQUEUE_CALLBACK_SUCCESS:
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+	spin_unlock(&lkb->lkb_cb_lock);
+}
+
+void dlm_callback_work(struct work_struct *work)
+{
+	struct dlm_lkb *lkb = container_of(work, struct dlm_lkb, lkb_cb_work);
+	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
+	void (*castfn) (void *astparam);
+	void (*bastfn) (void *astparam, int mode);
+	struct dlm_callback *cb;
+	int rv;
+
+	spin_lock(&lkb->lkb_cb_lock);
+	rv = dlm_dequeue_lkb_callback(lkb, &cb);
+	if (WARN_ON_ONCE(rv == DLM_DEQUEUE_CALLBACK_EMPTY)) {
+		clear_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags);
+		spin_unlock(&lkb->lkb_cb_lock);
+		goto out;
+	}
+	spin_unlock(&lkb->lkb_cb_lock);
+
+	for (;;) {
+		castfn = lkb->lkb_astfn;
+		bastfn = lkb->lkb_bastfn;
+
+		if (cb->flags & DLM_CB_BAST) {
+			trace_dlm_bast(ls, lkb, cb->mode);
+			lkb->lkb_last_bast_time = ktime_get();
+			lkb->lkb_last_bast_mode = cb->mode;
+			bastfn(lkb->lkb_astparam, cb->mode);
+		} else if (cb->flags & DLM_CB_CAST) {
+			lkb->lkb_lksb->sb_status = cb->sb_status;
+			lkb->lkb_lksb->sb_flags = cb->sb_flags;
+			trace_dlm_ast(ls, lkb);
+			lkb->lkb_last_cast_time = ktime_get();
+			castfn(lkb->lkb_astparam);
+		}
+
+		kref_put(&cb->ref, dlm_release_callback);
+
+		spin_lock(&lkb->lkb_cb_lock);
+		rv = dlm_dequeue_lkb_callback(lkb, &cb);
+		if (rv == DLM_DEQUEUE_CALLBACK_EMPTY) {
+			clear_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags);
+			spin_unlock(&lkb->lkb_cb_lock);
+			break;
+		}
+		spin_unlock(&lkb->lkb_cb_lock);
+	}
+
+out:
+	/* undo kref_get from dlm_add_callback, may cause lkb to be freed */
+	dlm_put_lkb(lkb);
+}
+
+int dlm_callback_start(struct dlm_ls *ls)
+{
+	ls->ls_callback_wq = alloc_workqueue("dlm_callback",
+					     WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
+	if (!ls->ls_callback_wq) {
+		log_print("can't start dlm_callback workqueue");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void dlm_callback_stop(struct dlm_ls *ls)
+{
+	if (ls->ls_callback_wq)
+		destroy_workqueue(ls->ls_callback_wq);
+}
+
+void dlm_callback_suspend(struct dlm_ls *ls)
+{
+	if (ls->ls_callback_wq) {
+		spin_lock(&ls->ls_cb_lock);
+		set_bit(LSFL_CB_DELAY, &ls->ls_flags);
+		spin_unlock(&ls->ls_cb_lock);
+
+		flush_workqueue(ls->ls_callback_wq);
+	}
+}
+
+#define MAX_CB_QUEUE 25
+
+void dlm_callback_resume(struct dlm_ls *ls)
+{
+	struct dlm_lkb *lkb, *safe;
+	int count = 0, sum = 0;
+	bool empty;
+
+	if (!ls->ls_callback_wq)
+		return;
+
+more:
+	spin_lock(&ls->ls_cb_lock);
+	list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
+		list_del_init(&lkb->lkb_cb_list);
+		queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
+		count++;
+		if (count == MAX_CB_QUEUE)
+			break;
+	}
+	empty = list_empty(&ls->ls_cb_delay);
+	if (empty)
+		clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
+	spin_unlock(&ls->ls_cb_lock);
+
+	sum += count;
+	if (!empty) {
+		count = 0;
+		cond_resched();
+		goto more;
+	}
+
+	if (sum)
+		log_rinfo(ls, "%s %d", __func__, sum);
+}
+