dlm: use workqueue for callbacks
Instead of creating our own kthread (dlm_astd) to deliver
callbacks for all lockspaces, use a per-lockspace workqueue
to deliver the callbacks. This eliminates complications and
slowdowns from many lockspaces sharing the same thread.
Signed-off-by: David Teigland <teigland@redhat.com>
diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
index abc49f2..4f29add 100644
--- a/fs/dlm/ast.c
+++ b/fs/dlm/ast.c
@@ -14,17 +14,9 @@
#include "dlm_internal.h"
#include "lock.h"
#include "user.h"
-#include "ast.h"
-#define WAKE_ASTS 0
-
-static uint64_t ast_seq_count;
-static struct list_head ast_queue;
-static spinlock_t ast_queue_lock;
-static struct task_struct * astd_task;
-static unsigned long astd_wakeflags;
-static struct mutex astd_running;
-
+static uint64_t dlm_cb_seq;
+static spinlock_t dlm_cb_seq_spin;
static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
{
@@ -57,21 +49,13 @@
}
}
-void dlm_del_ast(struct dlm_lkb *lkb)
-{
- spin_lock(&ast_queue_lock);
- if (!list_empty(&lkb->lkb_astqueue))
- list_del_init(&lkb->lkb_astqueue);
- spin_unlock(&ast_queue_lock);
-}
-
int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
int status, uint32_t sbflags, uint64_t seq)
{
struct dlm_ls *ls = lkb->lkb_resource->res_ls;
uint64_t prev_seq;
int prev_mode;
- int i;
+ int i, rv;
for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
if (lkb->lkb_callbacks[i].seq)
@@ -100,7 +84,8 @@
mode,
(unsigned long long)prev_seq,
prev_mode);
- return 0;
+ rv = 0;
+ goto out;
}
}
@@ -109,6 +94,7 @@
lkb->lkb_callbacks[i].mode = mode;
lkb->lkb_callbacks[i].sb_status = status;
lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);
+ rv = 0;
break;
}
@@ -117,21 +103,24 @@
lkb->lkb_id, (unsigned long long)seq,
flags, mode, status, sbflags);
dlm_dump_lkb_callbacks(lkb);
- return -1;
+ rv = -1;
+ goto out;
}
-
- return 0;
+ out:
+ return rv;
}
int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
struct dlm_callback *cb, int *resid)
{
- int i;
+ int i, rv;
*resid = 0;
- if (!lkb->lkb_callbacks[0].seq)
- return -ENOENT;
+ if (!lkb->lkb_callbacks[0].seq) {
+ rv = -ENOENT;
+ goto out;
+ }
/* oldest undelivered cb is callbacks[0] */
@@ -163,7 +152,8 @@
cb->mode,
(unsigned long long)lkb->lkb_last_cast.seq,
lkb->lkb_last_cast.mode);
- return 0;
+ rv = 0;
+ goto out;
}
}
@@ -176,171 +166,147 @@
memcpy(&lkb->lkb_last_bast, cb, sizeof(struct dlm_callback));
lkb->lkb_last_bast_time = ktime_get();
}
-
- return 0;
+ rv = 0;
+ out:
+ return rv;
}
-void dlm_add_ast(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
- uint32_t sbflags)
+void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
+ uint32_t sbflags)
{
- uint64_t seq;
+ struct dlm_ls *ls = lkb->lkb_resource->res_ls;
+ uint64_t new_seq, prev_seq;
int rv;
- spin_lock(&ast_queue_lock);
-
- seq = ++ast_seq_count;
+ spin_lock(&dlm_cb_seq_spin);
+ new_seq = ++dlm_cb_seq;
+ spin_unlock(&dlm_cb_seq_spin);
if (lkb->lkb_flags & DLM_IFL_USER) {
- spin_unlock(&ast_queue_lock);
- dlm_user_add_ast(lkb, flags, mode, status, sbflags, seq);
+ dlm_user_add_ast(lkb, flags, mode, status, sbflags, new_seq);
return;
}
- rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, seq);
- if (rv < 0) {
- spin_unlock(&ast_queue_lock);
- return;
- }
+ mutex_lock(&lkb->lkb_cb_mutex);
+ prev_seq = lkb->lkb_callbacks[0].seq;
- if (list_empty(&lkb->lkb_astqueue)) {
+ rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, new_seq);
+ if (rv < 0)
+ goto out;
+
+ if (!prev_seq) {
kref_get(&lkb->lkb_ref);
- list_add_tail(&lkb->lkb_astqueue, &ast_queue);
- }
- spin_unlock(&ast_queue_lock);
- set_bit(WAKE_ASTS, &astd_wakeflags);
- wake_up_process(astd_task);
+ if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
+ mutex_lock(&ls->ls_cb_mutex);
+ list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
+ mutex_unlock(&ls->ls_cb_mutex);
+ } else {
+ queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
+ }
+ }
+ out:
+ mutex_unlock(&lkb->lkb_cb_mutex);
}
-static void process_asts(void)
+void dlm_callback_work(struct work_struct *work)
{
- struct dlm_ls *ls = NULL;
- struct dlm_rsb *r = NULL;
- struct dlm_lkb *lkb;
+ 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 callbacks[DLM_CALLBACKS_SIZE];
int i, rv, resid;
-repeat:
- spin_lock(&ast_queue_lock);
- list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
- r = lkb->lkb_resource;
- ls = r->res_ls;
+ memset(&callbacks, 0, sizeof(callbacks));
- if (dlm_locking_stopped(ls))
- continue;
-
- /* we remove from astqueue list and remove everything in
- lkb_callbacks before releasing the spinlock so empty
- lkb_astqueue is always consistent with empty lkb_callbacks */
-
- list_del_init(&lkb->lkb_astqueue);
-
- castfn = lkb->lkb_astfn;
- bastfn = lkb->lkb_bastfn;
-
- memset(&callbacks, 0, sizeof(callbacks));
-
- for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
- rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
- if (rv < 0)
- break;
- }
- spin_unlock(&ast_queue_lock);
-
- if (resid) {
- /* shouldn't happen, for loop should have removed all */
- log_error(ls, "callback resid %d lkb %x",
- resid, lkb->lkb_id);
- }
-
- for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
- if (!callbacks[i].seq)
- break;
- if (callbacks[i].flags & DLM_CB_SKIP) {
- continue;
- } else if (callbacks[i].flags & DLM_CB_BAST) {
- bastfn(lkb->lkb_astparam, callbacks[i].mode);
- } else if (callbacks[i].flags & DLM_CB_CAST) {
- lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
- lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
- castfn(lkb->lkb_astparam);
- }
- }
-
- /* removes ref for ast_queue, may cause lkb to be freed */
- dlm_put_lkb(lkb);
-
- cond_resched();
- goto repeat;
+ mutex_lock(&lkb->lkb_cb_mutex);
+ if (!lkb->lkb_callbacks[0].seq) {
+ /* no callback work exists, shouldn't happen */
+ log_error(ls, "dlm_callback_work %x no work", lkb->lkb_id);
+ dlm_print_lkb(lkb);
+ dlm_dump_lkb_callbacks(lkb);
}
- spin_unlock(&ast_queue_lock);
+
+ for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
+ rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
+ if (rv < 0)
+ break;
+ }
+
+ if (resid) {
+ /* cbs remain, loop should have removed all, shouldn't happen */
+ log_error(ls, "dlm_callback_work %x resid %d", lkb->lkb_id,
+ resid);
+ dlm_print_lkb(lkb);
+ dlm_dump_lkb_callbacks(lkb);
+ }
+ mutex_unlock(&lkb->lkb_cb_mutex);
+
+ castfn = lkb->lkb_astfn;
+ bastfn = lkb->lkb_bastfn;
+
+ for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
+ if (!callbacks[i].seq)
+ break;
+ if (callbacks[i].flags & DLM_CB_SKIP) {
+ continue;
+ } else if (callbacks[i].flags & DLM_CB_BAST) {
+ bastfn(lkb->lkb_astparam, callbacks[i].mode);
+ } else if (callbacks[i].flags & DLM_CB_CAST) {
+ lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
+ lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
+ castfn(lkb->lkb_astparam);
+ }
+ }
+
+ /* undo kref_get from dlm_add_callback, may cause lkb to be freed */
+ dlm_put_lkb(lkb);
}
-static inline int no_asts(void)
+int dlm_callback_start(struct dlm_ls *ls)
{
- int ret;
-
- spin_lock(&ast_queue_lock);
- ret = list_empty(&ast_queue);
- spin_unlock(&ast_queue_lock);
- return ret;
-}
-
-static int dlm_astd(void *data)
-{
- while (!kthread_should_stop()) {
- set_current_state(TASK_INTERRUPTIBLE);
- if (!test_bit(WAKE_ASTS, &astd_wakeflags))
- schedule();
- set_current_state(TASK_RUNNING);
-
- mutex_lock(&astd_running);
- if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
- process_asts();
- mutex_unlock(&astd_running);
+ ls->ls_callback_wq = alloc_workqueue("dlm_callback",
+ WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
+ if (!ls->ls_callback_wq) {
+ log_print("can't start dlm_callback workqueue");
+ return -ENOMEM;
}
return 0;
}
-void dlm_astd_wake(void)
+void dlm_callback_stop(struct dlm_ls *ls)
{
- if (!no_asts()) {
- set_bit(WAKE_ASTS, &astd_wakeflags);
- wake_up_process(astd_task);
+ if (ls->ls_callback_wq)
+ destroy_workqueue(ls->ls_callback_wq);
+}
+
+void dlm_callback_suspend(struct dlm_ls *ls)
+{
+ set_bit(LSFL_CB_DELAY, &ls->ls_flags);
+
+ if (ls->ls_callback_wq)
+ flush_workqueue(ls->ls_callback_wq);
+}
+
+void dlm_callback_resume(struct dlm_ls *ls)
+{
+ struct dlm_lkb *lkb, *safe;
+ int count = 0;
+
+ clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
+
+ if (!ls->ls_callback_wq)
+ return;
+
+ mutex_lock(&ls->ls_cb_mutex);
+ 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++;
}
-}
+ mutex_unlock(&ls->ls_cb_mutex);
-int dlm_astd_start(void)
-{
- struct task_struct *p;
- int error = 0;
-
- INIT_LIST_HEAD(&ast_queue);
- spin_lock_init(&ast_queue_lock);
- mutex_init(&astd_running);
-
- p = kthread_run(dlm_astd, NULL, "dlm_astd");
- if (IS_ERR(p))
- error = PTR_ERR(p);
- else
- astd_task = p;
- return error;
-}
-
-void dlm_astd_stop(void)
-{
- kthread_stop(astd_task);
-}
-
-void dlm_astd_suspend(void)
-{
- mutex_lock(&astd_running);
-}
-
-void dlm_astd_resume(void)
-{
- mutex_unlock(&astd_running);
+ log_debug(ls, "dlm_callback_resume %d", count);
}