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linux/fs/dlm/ast.c
Alexander Aring 68bde2a67a dlm: implement LSFL_SOFTIRQ_SAFE
When a lockspace user allows it, run callback functions directly from
softirq context, instead of queueing callbacks to be run from the
dlm_callback workqueue context.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2024-06-11 13:13:00 -05:00

276 lines
6.9 KiB
C

// 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 "lvb_table.h"
#include "memory.h"
#include "lock.h"
#include "user.h"
#include "ast.h"
static void dlm_run_callback(uint32_t ls_id, uint32_t lkb_id, int8_t mode,
uint32_t flags, uint8_t sb_flags, int sb_status,
struct dlm_lksb *lksb,
void (*astfn)(void *astparam),
void (*bastfn)(void *astparam, int mode),
void *astparam, const char *res_name,
size_t res_length)
{
if (flags & DLM_CB_BAST) {
trace_dlm_bast(ls_id, lkb_id, mode, res_name, res_length);
bastfn(astparam, mode);
} else if (flags & DLM_CB_CAST) {
trace_dlm_ast(ls_id, lkb_id, sb_status, sb_flags, res_name,
res_length);
lksb->sb_status = sb_status;
lksb->sb_flags = sb_flags;
astfn(astparam);
}
}
static void dlm_do_callback(struct dlm_callback *cb)
{
dlm_run_callback(cb->ls_id, cb->lkb_id, cb->mode, cb->flags,
cb->sb_flags, cb->sb_status, cb->lkb_lksb,
cb->astfn, cb->bastfn, cb->astparam,
cb->res_name, cb->res_length);
dlm_free_cb(cb);
}
static void dlm_callback_work(struct work_struct *work)
{
struct dlm_callback *cb = container_of(work, struct dlm_callback, work);
dlm_do_callback(cb);
}
bool dlm_may_skip_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
int status, uint32_t sbflags, int *copy_lvb)
{
struct dlm_rsb *rsb = lkb->lkb_resource;
struct dlm_ls *ls = rsb->res_ls;
int prev_mode;
if (copy_lvb)
*copy_lvb = 0;
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_cb_mode != -1) {
if (dlm_modes_compat(mode, lkb->lkb_last_cast_cb_mode)) {
log_debug(ls, "skip %x bast mode %d for cast mode %d",
lkb->lkb_id, mode,
lkb->lkb_last_cast_cb_mode);
return true;
}
}
/*
* 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_mode != -1 &&
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);
return true;
}
}
lkb->lkb_last_bast_time = ktime_get();
lkb->lkb_last_bast_cb_mode = mode;
} else if (flags & DLM_CB_CAST) {
if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
prev_mode = lkb->lkb_last_cast_cb_mode;
if (!status && lkb->lkb_lksb->sb_lvbptr &&
dlm_lvb_operations[prev_mode + 1][mode + 1]) {
if (copy_lvb)
*copy_lvb = 1;
}
}
lkb->lkb_last_cast_cb_mode = mode;
lkb->lkb_last_cast_time = ktime_get();
}
lkb->lkb_last_cb_mode = mode;
lkb->lkb_last_cb_flags = flags;
return false;
}
int dlm_get_cb(struct dlm_lkb *lkb, uint32_t flags, int mode,
int status, uint32_t sbflags,
struct dlm_callback **cb)
{
struct dlm_rsb *rsb = lkb->lkb_resource;
struct dlm_ls *ls = rsb->res_ls;
*cb = dlm_allocate_cb();
if (WARN_ON_ONCE(!*cb))
return -ENOMEM;
/* for tracing */
(*cb)->lkb_id = lkb->lkb_id;
(*cb)->ls_id = ls->ls_global_id;
memcpy((*cb)->res_name, rsb->res_name, rsb->res_length);
(*cb)->res_length = rsb->res_length;
(*cb)->flags = flags;
(*cb)->mode = mode;
(*cb)->sb_status = status;
(*cb)->sb_flags = (sbflags & 0x000000FF);
(*cb)->lkb_lksb = lkb->lkb_lksb;
return 0;
}
static int dlm_get_queue_cb(struct dlm_lkb *lkb, uint32_t flags, int mode,
int status, uint32_t sbflags,
struct dlm_callback **cb)
{
int rv;
rv = dlm_get_cb(lkb, flags, mode, status, sbflags, cb);
if (rv)
return rv;
(*cb)->astfn = lkb->lkb_astfn;
(*cb)->bastfn = lkb->lkb_bastfn;
(*cb)->astparam = lkb->lkb_astparam;
INIT_WORK(&(*cb)->work, dlm_callback_work);
return 0;
}
void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
uint32_t sbflags)
{
struct dlm_rsb *rsb = lkb->lkb_resource;
struct dlm_ls *ls = rsb->res_ls;
struct dlm_callback *cb;
int rv;
if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
dlm_user_add_ast(lkb, flags, mode, status, sbflags);
return;
}
if (dlm_may_skip_callback(lkb, flags, mode, status, sbflags, NULL))
return;
spin_lock_bh(&ls->ls_cb_lock);
if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
rv = dlm_get_queue_cb(lkb, flags, mode, status, sbflags, &cb);
if (!rv)
list_add(&cb->list, &ls->ls_cb_delay);
} else {
if (test_bit(LSFL_SOFTIRQ, &ls->ls_flags)) {
dlm_run_callback(ls->ls_global_id, lkb->lkb_id, mode, flags,
sbflags, status, lkb->lkb_lksb,
lkb->lkb_astfn, lkb->lkb_bastfn,
lkb->lkb_astparam, rsb->res_name,
rsb->res_length);
} else {
rv = dlm_get_queue_cb(lkb, flags, mode, status, sbflags, &cb);
if (!rv)
queue_work(ls->ls_callback_wq, &cb->work);
}
}
spin_unlock_bh(&ls->ls_cb_lock);
}
int dlm_callback_start(struct dlm_ls *ls)
{
if (!test_bit(LSFL_FS, &ls->ls_flags) ||
test_bit(LSFL_SOFTIRQ, &ls->ls_flags))
return 0;
ls->ls_callback_wq = alloc_ordered_workqueue("dlm_callback",
WQ_HIGHPRI | WQ_MEM_RECLAIM);
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 (!test_bit(LSFL_FS, &ls->ls_flags))
return;
spin_lock_bh(&ls->ls_cb_lock);
set_bit(LSFL_CB_DELAY, &ls->ls_flags);
spin_unlock_bh(&ls->ls_cb_lock);
if (ls->ls_callback_wq)
flush_workqueue(ls->ls_callback_wq);
}
#define MAX_CB_QUEUE 25
void dlm_callback_resume(struct dlm_ls *ls)
{
struct dlm_callback *cb, *safe;
int count = 0, sum = 0;
bool empty;
if (!test_bit(LSFL_FS, &ls->ls_flags))
return;
more:
spin_lock_bh(&ls->ls_cb_lock);
list_for_each_entry_safe(cb, safe, &ls->ls_cb_delay, list) {
list_del(&cb->list);
if (test_bit(LSFL_SOFTIRQ, &ls->ls_flags))
dlm_do_callback(cb);
else
queue_work(ls->ls_callback_wq, &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_bh(&ls->ls_cb_lock);
sum += count;
if (!empty) {
count = 0;
cond_resched();
goto more;
}
if (sum)
log_rinfo(ls, "%s %d", __func__, sum);
}