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dlm: use workqueue for callbacks
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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>
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David Teigland committed Jul 15, 2011
1 parent 883ba74 commit 23e8e1a
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Showing 7 changed files with 172 additions and 205 deletions.
262 changes: 114 additions & 148 deletions fs/dlm/ast.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand Down Expand Up @@ -57,21 +49,13 @@ static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
}
}

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)
Expand Down Expand Up @@ -100,7 +84,8 @@ int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
mode,
(unsigned long long)prev_seq,
prev_mode);
return 0;
rv = 0;
goto out;
}
}

Expand All @@ -109,6 +94,7 @@ int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
lkb->lkb_callbacks[i].mode = mode;
lkb->lkb_callbacks[i].sb_status = status;
lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);
rv = 0;
break;
}

Expand All @@ -117,21 +103,24 @@ int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
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] */

Expand Down Expand Up @@ -163,7 +152,8 @@ int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
cb->mode,
(unsigned long long)lkb->lkb_last_cast.seq,
lkb->lkb_last_cast.mode);
return 0;
rv = 0;
goto out;
}
}

Expand All @@ -176,171 +166,147 @@ int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
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;
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);
}

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;
}

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) {
/* 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);

if (resid) {
/* shouldn't happen, for loop should have removed all */
log_error(ls, "callback resid %d lkb %x",
resid, lkb->lkb_id);
}
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);
}
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;
}
spin_unlock(&ast_queue_lock);
}

static inline int no_asts(void)
{
int ret;

spin_lock(&ast_queue_lock);
ret = list_empty(&ast_queue);
spin_unlock(&ast_queue_lock);
return ret;
/* undo kref_get from dlm_add_callback, may cause lkb to be freed */
dlm_put_lkb(lkb);
}

static int dlm_astd(void *data)
int dlm_callback_start(struct dlm_ls *ls)
{
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);
}

int dlm_astd_start(void)
void dlm_callback_suspend(struct dlm_ls *ls)
{
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;
}
set_bit(LSFL_CB_DELAY, &ls->ls_flags);

void dlm_astd_stop(void)
{
kthread_stop(astd_task);
if (ls->ls_callback_wq)
flush_workqueue(ls->ls_callback_wq);
}

void dlm_astd_suspend(void)
void dlm_callback_resume(struct dlm_ls *ls)
{
mutex_lock(&astd_running);
}
struct dlm_lkb *lkb, *safe;
int count = 0;

void dlm_astd_resume(void)
{
mutex_unlock(&astd_running);
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);

log_debug(ls, "dlm_callback_resume %d", count);
}

15 changes: 8 additions & 7 deletions fs/dlm/ast.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,14 +18,15 @@ int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
int status, uint32_t sbflags, uint64_t seq);
int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
struct dlm_callback *cb, int *resid);
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);

void dlm_astd_wake(void);
int dlm_astd_start(void);
void dlm_astd_stop(void);
void dlm_astd_suspend(void);
void dlm_astd_resume(void);
void dlm_callback_work(struct work_struct *work);
int dlm_callback_start(struct dlm_ls *ls);
void dlm_callback_stop(struct dlm_ls *ls);
void dlm_callback_suspend(struct dlm_ls *ls);
void dlm_callback_resume(struct dlm_ls *ls);

#endif


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