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/*
* Copyright (C) 2005-2017 Junjiro R. Okajima
*
* This program, aufs is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* workqueue for asynchronous/super-io operations
* todo: try new dredential scheme
*/
#include <linux/module.h>
#include "aufs.h"
/* internal workqueue named AUFS_WKQ_NAME */
static struct workqueue_struct *au_wkq;
struct au_wkinfo {
struct work_struct wk;
struct kobject *kobj;
unsigned int flags; /* see wkq.h */
au_wkq_func_t func;
void *args;
struct completion *comp;
};
/* ---------------------------------------------------------------------- */
static void wkq_func(struct work_struct *wk)
{
struct au_wkinfo *wkinfo = container_of(wk, struct au_wkinfo, wk);
AuDebugOn(!uid_eq(current_fsuid(), GLOBAL_ROOT_UID));
AuDebugOn(rlimit(RLIMIT_FSIZE) != RLIM_INFINITY);
wkinfo->func(wkinfo->args);
if (au_ftest_wkq(wkinfo->flags, WAIT))
complete(wkinfo->comp);
else {
kobject_put(wkinfo->kobj);
module_put(THIS_MODULE); /* todo: ?? */
kfree(wkinfo);
}
}
/*
* Since struct completion is large, try allocating it dynamically.
*/
#if 1 /* defined(CONFIG_4KSTACKS) || defined(AuTest4KSTACKS) */
#define AuWkqCompDeclare(name) struct completion *comp = NULL
static int au_wkq_comp_alloc(struct au_wkinfo *wkinfo, struct completion **comp)
{
*comp = kmalloc(sizeof(**comp), GFP_NOFS);
if (*comp) {
init_completion(*comp);
wkinfo->comp = *comp;
return 0;
}
return -ENOMEM;
}
static void au_wkq_comp_free(struct completion *comp)
{
kfree(comp);
}
#else
/* no braces */
#define AuWkqCompDeclare(name) \
DECLARE_COMPLETION_ONSTACK(_ ## name); \
struct completion *comp = &_ ## name
static int au_wkq_comp_alloc(struct au_wkinfo *wkinfo, struct completion **comp)
{
wkinfo->comp = *comp;
return 0;
}
static void au_wkq_comp_free(struct completion *comp __maybe_unused)
{
/* empty */
}
#endif /* 4KSTACKS */
static void au_wkq_run(struct au_wkinfo *wkinfo)
{
if (au_ftest_wkq(wkinfo->flags, NEST)) {
if (au_wkq_test()) {
AuWarn1("wkq from wkq, unless silly-rename on NFS,"
" due to a dead dir by UDBA?\n");
AuDebugOn(au_ftest_wkq(wkinfo->flags, WAIT));
}
} else
au_dbg_verify_kthread();
if (au_ftest_wkq(wkinfo->flags, WAIT)) {
INIT_WORK_ONSTACK(&wkinfo->wk, wkq_func);
queue_work(au_wkq, &wkinfo->wk);
} else {
INIT_WORK(&wkinfo->wk, wkq_func);
schedule_work(&wkinfo->wk);
}
}
/*
* Be careful. It is easy to make deadlock happen.
* processA: lock, wkq and wait
* processB: wkq and wait, lock in wkq
* --> deadlock
*/
int au_wkq_do_wait(unsigned int flags, au_wkq_func_t func, void *args)
{
int err;
AuWkqCompDeclare(comp);
struct au_wkinfo wkinfo = {
.flags = flags,
.func = func,
.args = args
};
err = au_wkq_comp_alloc(&wkinfo, &comp);
if (!err) {
au_wkq_run(&wkinfo);
/* no timeout, no interrupt */
wait_for_completion(wkinfo.comp);
au_wkq_comp_free(comp);
destroy_work_on_stack(&wkinfo.wk);
}
return err;
}
/*
* Note: dget/dput() in func for aufs dentries are not supported. It will be a
* problem in a concurrent umounting.
*/
int au_wkq_nowait(au_wkq_func_t func, void *args, struct super_block *sb,
unsigned int flags)
{
int err;
struct au_wkinfo *wkinfo;
atomic_inc(&au_sbi(sb)->si_nowait.nw_len);
/*
* wkq_func() must free this wkinfo.
* it highly depends upon the implementation of workqueue.
*/
err = 0;
wkinfo = kmalloc(sizeof(*wkinfo), GFP_NOFS);
if (wkinfo) {
wkinfo->kobj = &au_sbi(sb)->si_kobj;
wkinfo->flags = flags & ~AuWkq_WAIT;
wkinfo->func = func;
wkinfo->args = args;
wkinfo->comp = NULL;
kobject_get(wkinfo->kobj);
__module_get(THIS_MODULE); /* todo: ?? */
au_wkq_run(wkinfo);
} else {
err = -ENOMEM;
au_nwt_done(&au_sbi(sb)->si_nowait);
}
return err;
}
/* ---------------------------------------------------------------------- */
void au_nwt_init(struct au_nowait_tasks *nwt)
{
atomic_set(&nwt->nw_len, 0);
/* smp_mb(); */ /* atomic_set */
init_waitqueue_head(&nwt->nw_wq);
}
void au_wkq_fin(void)
{
destroy_workqueue(au_wkq);
}
int __init au_wkq_init(void)
{
int err;
err = 0;
au_wkq = alloc_workqueue(AUFS_WKQ_NAME, 0, WQ_DFL_ACTIVE);
if (IS_ERR(au_wkq))
err = PTR_ERR(au_wkq);
else if (!au_wkq)
err = -ENOMEM;
return err;
}
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