/usr/src/aufs-4.9+20161219/fs/aufs/wkq.c is in aufs-dkms 4.9+20161219-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 | /*
* Copyright (C) 2005-2016 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: ?? */
au_delayed_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)
{
au_delayed_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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