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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /fs/aufs/wkq.c
Initial import
Diffstat (limited to 'fs/aufs/wkq.c')
-rw-r--r--fs/aufs/wkq.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/fs/aufs/wkq.c b/fs/aufs/wkq.c
new file mode 100644
index 000000000..3ffedae93
--- /dev/null
+++ b/fs/aufs/wkq.c
@@ -0,0 +1,213 @@
+/*
+ * Copyright (C) 2005-2015 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;
+}