xref: /kernel/linux/linux-6.6/fs/dlm/ast.c (revision 62306a36) 
1// SPDX-License-Identifier: GPL-2.0-only
2/******************************************************************************
3*******************************************************************************
4**
5**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
6**  Copyright (C) 2004-2010 Red Hat, Inc.  All rights reserved.
7**
8**
9*******************************************************************************
10******************************************************************************/
11
12#include <trace/events/dlm.h>
13
14#include "dlm_internal.h"
15#include "memory.h"
16#include "lock.h"
17#include "user.h"
18#include "ast.h"
19
20void dlm_release_callback(struct kref *ref)
21{
22	struct dlm_callback *cb = container_of(ref, struct dlm_callback, ref);
23
24	dlm_free_cb(cb);
25}
26
27void dlm_callback_set_last_ptr(struct dlm_callback **from,
28			       struct dlm_callback *to)
29{
30	if (*from)
31		kref_put(&(*from)->ref, dlm_release_callback);
32
33	if (to)
34		kref_get(&to->ref);
35
36	*from = to;
37}
38
39int dlm_enqueue_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
40			     int status, uint32_t sbflags)
41{
42	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
43	int rv = DLM_ENQUEUE_CALLBACK_SUCCESS;
44	struct dlm_callback *cb;
45	int prev_mode;
46
47	if (flags & DLM_CB_BAST) {
48		/* if cb is a bast, it should be skipped if the blocking mode is
49		 * compatible with the last granted mode
50		 */
51		if (lkb->lkb_last_cast) {
52			if (dlm_modes_compat(mode, lkb->lkb_last_cast->mode)) {
53				log_debug(ls, "skip %x bast mode %d for cast mode %d",
54					  lkb->lkb_id, mode,
55					  lkb->lkb_last_cast->mode);
56				goto out;
57			}
58		}
59
60		/*
61		 * Suppress some redundant basts here, do more on removal.
62		 * Don't even add a bast if the callback just before it
63		 * is a bast for the same mode or a more restrictive mode.
64		 * (the addional > PR check is needed for PR/CW inversion)
65		 */
66		if (lkb->lkb_last_cb && lkb->lkb_last_cb->flags & DLM_CB_BAST) {
67			prev_mode = lkb->lkb_last_cb->mode;
68
69			if ((prev_mode == mode) ||
70			    (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
71				log_debug(ls, "skip %x add bast mode %d for bast mode %d",
72					  lkb->lkb_id, mode, prev_mode);
73				goto out;
74			}
75		}
76	}
77
78	cb = dlm_allocate_cb();
79	if (!cb) {
80		rv = DLM_ENQUEUE_CALLBACK_FAILURE;
81		goto out;
82	}
83
84	cb->flags = flags;
85	cb->mode = mode;
86	cb->sb_status = status;
87	cb->sb_flags = (sbflags & 0x000000FF);
88	kref_init(&cb->ref);
89	if (!test_and_set_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags))
90		rv = DLM_ENQUEUE_CALLBACK_NEED_SCHED;
91
92	list_add_tail(&cb->list, &lkb->lkb_callbacks);
93
94	if (flags & DLM_CB_CAST)
95		dlm_callback_set_last_ptr(&lkb->lkb_last_cast, cb);
96
97	dlm_callback_set_last_ptr(&lkb->lkb_last_cb, cb);
98
99 out:
100	return rv;
101}
102
103int dlm_dequeue_lkb_callback(struct dlm_lkb *lkb, struct dlm_callback **cb)
104{
105	/* oldest undelivered cb is callbacks first entry */
106	*cb = list_first_entry_or_null(&lkb->lkb_callbacks,
107				       struct dlm_callback, list);
108	if (!*cb)
109		return DLM_DEQUEUE_CALLBACK_EMPTY;
110
111	/* remove it from callbacks so shift others down */
112	list_del(&(*cb)->list);
113	if (list_empty(&lkb->lkb_callbacks))
114		return DLM_DEQUEUE_CALLBACK_LAST;
115
116	return DLM_DEQUEUE_CALLBACK_SUCCESS;
117}
118
119void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
120		uint32_t sbflags)
121{
122	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
123	int rv;
124
125	if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
126		dlm_user_add_ast(lkb, flags, mode, status, sbflags);
127		return;
128	}
129
130	spin_lock(&lkb->lkb_cb_lock);
131	rv = dlm_enqueue_lkb_callback(lkb, flags, mode, status, sbflags);
132	switch (rv) {
133	case DLM_ENQUEUE_CALLBACK_NEED_SCHED:
134		kref_get(&lkb->lkb_ref);
135
136		spin_lock(&ls->ls_cb_lock);
137		if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
138			list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
139		} else {
140			queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
141		}
142		spin_unlock(&ls->ls_cb_lock);
143		break;
144	case DLM_ENQUEUE_CALLBACK_FAILURE:
145		WARN_ON_ONCE(1);
146		break;
147	case DLM_ENQUEUE_CALLBACK_SUCCESS:
148		break;
149	default:
150		WARN_ON_ONCE(1);
151		break;
152	}
153	spin_unlock(&lkb->lkb_cb_lock);
154}
155
156void dlm_callback_work(struct work_struct *work)
157{
158	struct dlm_lkb *lkb = container_of(work, struct dlm_lkb, lkb_cb_work);
159	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
160	void (*castfn) (void *astparam);
161	void (*bastfn) (void *astparam, int mode);
162	struct dlm_callback *cb;
163	int rv;
164
165	spin_lock(&lkb->lkb_cb_lock);
166	rv = dlm_dequeue_lkb_callback(lkb, &cb);
167	if (WARN_ON_ONCE(rv == DLM_DEQUEUE_CALLBACK_EMPTY)) {
168		clear_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags);
169		spin_unlock(&lkb->lkb_cb_lock);
170		goto out;
171	}
172	spin_unlock(&lkb->lkb_cb_lock);
173
174	for (;;) {
175		castfn = lkb->lkb_astfn;
176		bastfn = lkb->lkb_bastfn;
177
178		if (cb->flags & DLM_CB_BAST) {
179			trace_dlm_bast(ls, lkb, cb->mode);
180			lkb->lkb_last_bast_time = ktime_get();
181			lkb->lkb_last_bast_mode = cb->mode;
182			bastfn(lkb->lkb_astparam, cb->mode);
183		} else if (cb->flags & DLM_CB_CAST) {
184			lkb->lkb_lksb->sb_status = cb->sb_status;
185			lkb->lkb_lksb->sb_flags = cb->sb_flags;
186			trace_dlm_ast(ls, lkb);
187			lkb->lkb_last_cast_time = ktime_get();
188			castfn(lkb->lkb_astparam);
189		}
190
191		kref_put(&cb->ref, dlm_release_callback);
192
193		spin_lock(&lkb->lkb_cb_lock);
194		rv = dlm_dequeue_lkb_callback(lkb, &cb);
195		if (rv == DLM_DEQUEUE_CALLBACK_EMPTY) {
196			clear_bit(DLM_IFL_CB_PENDING_BIT, &lkb->lkb_iflags);
197			spin_unlock(&lkb->lkb_cb_lock);
198			break;
199		}
200		spin_unlock(&lkb->lkb_cb_lock);
201	}
202
203out:
204	/* undo kref_get from dlm_add_callback, may cause lkb to be freed */
205	dlm_put_lkb(lkb);
206}
207
208int dlm_callback_start(struct dlm_ls *ls)
209{
210	ls->ls_callback_wq = alloc_workqueue("dlm_callback",
211					     WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
212	if (!ls->ls_callback_wq) {
213		log_print("can't start dlm_callback workqueue");
214		return -ENOMEM;
215	}
216	return 0;
217}
218
219void dlm_callback_stop(struct dlm_ls *ls)
220{
221	if (ls->ls_callback_wq)
222		destroy_workqueue(ls->ls_callback_wq);
223}
224
225void dlm_callback_suspend(struct dlm_ls *ls)
226{
227	if (ls->ls_callback_wq) {
228		spin_lock(&ls->ls_cb_lock);
229		set_bit(LSFL_CB_DELAY, &ls->ls_flags);
230		spin_unlock(&ls->ls_cb_lock);
231
232		flush_workqueue(ls->ls_callback_wq);
233	}
234}
235
236#define MAX_CB_QUEUE 25
237
238void dlm_callback_resume(struct dlm_ls *ls)
239{
240	struct dlm_lkb *lkb, *safe;
241	int count = 0, sum = 0;
242	bool empty;
243
244	if (!ls->ls_callback_wq)
245		return;
246
247more:
248	spin_lock(&ls->ls_cb_lock);
249	list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
250		list_del_init(&lkb->lkb_cb_list);
251		queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
252		count++;
253		if (count == MAX_CB_QUEUE)
254			break;
255	}
256	empty = list_empty(&ls->ls_cb_delay);
257	if (empty)
258		clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
259	spin_unlock(&ls->ls_cb_lock);
260
261	sum += count;
262	if (!empty) {
263		count = 0;
264		cond_resched();
265		goto more;
266	}
267
268	if (sum)
269		log_rinfo(ls, "%s %d", __func__, sum);
270}
271
272