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Message-Id: <200611152258.52160.rjw@sisk.pl>
Date: Wed, 15 Nov 2006 22:58:51 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Pavel Machek <pavel@....cz>
Cc: David Chinner <dgc@....com>, Alasdair G Kergon <agk@...hat.com>,
Eric Sandeen <sandeen@...hat.com>,
Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
dm-devel@...hat.com, Srinivasa DS <srinivasa@...ibm.com>,
Nigel Cunningham <nigel@...pend2.net>
Subject: Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex
Hi,
On Wednesday, 15 November 2006 21:23, Pavel Machek wrote:
> Hi!
>
> > > There's one more thing, actually. If the on-disk data and metadata are
> > > changed _after_ the sync we do and _before_ we create the snapshot image,
> > > and the subsequent resume fails,
> >
> > Well, but this is equivalent to a power failure immediately after the sync, so
> > there _must_ be a way to recover the filesystem from that, no?
>
> Exactly.
>
> > I think I'll prepare a patch for freezing the work queues and we'll see what
> > to do next.
>
> Thanks!
Okay, the patch follows.
I've been running it for some time on my boxes and it doesn't seem to break
anything. However, I don't use XFS, so well ...
Greetings,
Rafael
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
fs/xfs/linux-2.6/xfs_buf.c | 4 ++--
include/linux/workqueue.h | 8 +++++---
kernel/workqueue.c | 20 ++++++++++++++------
3 files changed, 21 insertions(+), 11 deletions(-)
Index: linux-2.6.19-rc5-mm2/include/linux/workqueue.h
===================================================================
--- linux-2.6.19-rc5-mm2.orig/include/linux/workqueue.h 2006-09-20 05:42:06.000000000 +0200
+++ linux-2.6.19-rc5-mm2/include/linux/workqueue.h 2006-11-15 21:58:40.000000000 +0100
@@ -55,9 +55,11 @@ struct execute_work {
} while (0)
extern struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread);
-#define create_workqueue(name) __create_workqueue((name), 0)
-#define create_singlethread_workqueue(name) __create_workqueue((name), 1)
+ int singlethread,
+ int freezeable);
+#define create_workqueue(name) __create_workqueue((name), 0, 0)
+#define create_freezeable_workqueue(name) __create_workqueue((name), 0, 1)
+#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
extern void destroy_workqueue(struct workqueue_struct *wq);
Index: linux-2.6.19-rc5-mm2/kernel/workqueue.c
===================================================================
--- linux-2.6.19-rc5-mm2.orig/kernel/workqueue.c 2006-11-15 21:32:13.000000000 +0100
+++ linux-2.6.19-rc5-mm2/kernel/workqueue.c 2006-11-15 22:27:40.000000000 +0100
@@ -31,6 +31,7 @@
#include <linux/mempolicy.h>
#include <linux/kallsyms.h>
#include <linux/debug_locks.h>
+#include <linux/freezer.h>
/*
* The per-CPU workqueue (if single thread, we always use the first
@@ -57,6 +58,8 @@ struct cpu_workqueue_struct {
struct task_struct *thread;
int run_depth; /* Detect run_workqueue() recursion depth */
+
+ int freezeable; /* Freeze the thread during suspend */
} ____cacheline_aligned;
/*
@@ -251,7 +254,8 @@ static int worker_thread(void *__cwq)
struct k_sigaction sa;
sigset_t blocked;
- current->flags |= PF_NOFREEZE;
+ if (!cwq->freezeable)
+ current->flags |= PF_NOFREEZE;
set_user_nice(current, -5);
@@ -274,6 +278,9 @@ static int worker_thread(void *__cwq)
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
+ if (cwq->freezeable)
+ try_to_freeze();
+
add_wait_queue(&cwq->more_work, &wait);
if (list_empty(&cwq->worklist))
schedule();
@@ -350,7 +357,7 @@ void fastcall flush_workqueue(struct wor
EXPORT_SYMBOL_GPL(flush_workqueue);
static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
- int cpu)
+ int cpu, int freezeable)
{
struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
struct task_struct *p;
@@ -360,6 +367,7 @@ static struct task_struct *create_workqu
cwq->thread = NULL;
cwq->insert_sequence = 0;
cwq->remove_sequence = 0;
+ cwq->freezeable = freezeable;
INIT_LIST_HEAD(&cwq->worklist);
init_waitqueue_head(&cwq->more_work);
init_waitqueue_head(&cwq->work_done);
@@ -375,7 +383,7 @@ static struct task_struct *create_workqu
}
struct workqueue_struct *__create_workqueue(const char *name,
- int singlethread)
+ int singlethread, int freezeable)
{
int cpu, destroy = 0;
struct workqueue_struct *wq;
@@ -395,7 +403,7 @@ struct workqueue_struct *__create_workqu
mutex_lock(&workqueue_mutex);
if (singlethread) {
INIT_LIST_HEAD(&wq->list);
- p = create_workqueue_thread(wq, singlethread_cpu);
+ p = create_workqueue_thread(wq, singlethread_cpu, freezeable);
if (!p)
destroy = 1;
else
@@ -403,7 +411,7 @@ struct workqueue_struct *__create_workqu
} else {
list_add(&wq->list, &workqueues);
for_each_online_cpu(cpu) {
- p = create_workqueue_thread(wq, cpu);
+ p = create_workqueue_thread(wq, cpu, freezeable);
if (p) {
kthread_bind(p, cpu);
wake_up_process(p);
@@ -657,7 +665,7 @@ static int __devinit workqueue_cpu_callb
mutex_lock(&workqueue_mutex);
/* Create a new workqueue thread for it. */
list_for_each_entry(wq, &workqueues, list) {
- if (!create_workqueue_thread(wq, hotcpu)) {
+ if (!create_workqueue_thread(wq, hotcpu, 0)) {
printk("workqueue for %i failed\n", hotcpu);
return NOTIFY_BAD;
}
Index: linux-2.6.19-rc5-mm2/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- linux-2.6.19-rc5-mm2.orig/fs/xfs/linux-2.6/xfs_buf.c 2006-11-15 21:32:08.000000000 +0100
+++ linux-2.6.19-rc5-mm2/fs/xfs/linux-2.6/xfs_buf.c 2006-11-15 22:12:43.000000000 +0100
@@ -1826,11 +1826,11 @@ xfs_buf_init(void)
if (!xfs_buf_zone)
goto out_free_trace_buf;
- xfslogd_workqueue = create_workqueue("xfslogd");
+ xfslogd_workqueue = create_freezeable_workqueue("xfslogd");
if (!xfslogd_workqueue)
goto out_free_buf_zone;
- xfsdatad_workqueue = create_workqueue("xfsdatad");
+ xfsdatad_workqueue = create_freezeable_workqueue("xfsdatad");
if (!xfsdatad_workqueue)
goto out_destroy_xfslogd_workqueue;
-
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