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authorJosef Bacik <josef@redhat.com>2011-11-18 14:37:27 -0500
committerJosef Bacik <josef@redhat.com>2011-12-15 11:04:21 -0500
commit0dc3b84a73267f47a75468f924f5d58a840e3152 (patch)
tree0c2f64c2884a0de54e3fe15971e960f71a722afb /fs/btrfs/async-thread.c
parent5dbc8fca8ef5d719014f22345d990e957dcfc692 (diff)
downloadlinux-0dc3b84a73267f47a75468f924f5d58a840e3152.tar.bz2
Btrfs: fix num_workers_starting bug and other bugs in async thread
Al pointed out we have some random problems with the way we account for num_workers_starting in the async thread stuff. First of all we need to make sure to decrement num_workers_starting if we fail to start the worker, so make __btrfs_start_workers do this. Also fix __btrfs_start_workers so that it doesn't call btrfs_stop_workers(), there is no point in stopping everybody if we failed to create a worker. Also check_pending_worker_creates needs to call __btrfs_start_work in it's work function since it already increments num_workers_starting. People only start one worker at a time, so get rid of the num_workers argument everywhere, and make btrfs_queue_worker a void since it will always succeed. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
Diffstat (limited to 'fs/btrfs/async-thread.c')
-rw-r--r--fs/btrfs/async-thread.c115
1 files changed, 54 insertions, 61 deletions
diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 7ec14097fef1..af8e117c8978 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -64,6 +64,8 @@ struct btrfs_worker_thread {
int idle;
};
+static int __btrfs_start_workers(struct btrfs_workers *workers);
+
/*
* btrfs_start_workers uses kthread_run, which can block waiting for memory
* for a very long time. It will actually throttle on page writeback,
@@ -88,27 +90,10 @@ static void start_new_worker_func(struct btrfs_work *work)
{
struct worker_start *start;
start = container_of(work, struct worker_start, work);
- btrfs_start_workers(start->queue, 1);
+ __btrfs_start_workers(start->queue);
kfree(start);
}
-static int start_new_worker(struct btrfs_workers *queue)
-{
- struct worker_start *start;
- int ret;
-
- start = kzalloc(sizeof(*start), GFP_NOFS);
- if (!start)
- return -ENOMEM;
-
- start->work.func = start_new_worker_func;
- start->queue = queue;
- ret = btrfs_queue_worker(queue->atomic_worker_start, &start->work);
- if (ret)
- kfree(start);
- return ret;
-}
-
/*
* helper function to move a thread onto the idle list after it
* has finished some requests.
@@ -153,12 +138,20 @@ static void check_busy_worker(struct btrfs_worker_thread *worker)
static void check_pending_worker_creates(struct btrfs_worker_thread *worker)
{
struct btrfs_workers *workers = worker->workers;
+ struct worker_start *start;
unsigned long flags;
rmb();
if (!workers->atomic_start_pending)
return;
+ start = kzalloc(sizeof(*start), GFP_NOFS);
+ if (!start)
+ return;
+
+ start->work.func = start_new_worker_func;
+ start->queue = workers;
+
spin_lock_irqsave(&workers->lock, flags);
if (!workers->atomic_start_pending)
goto out;
@@ -170,10 +163,11 @@ static void check_pending_worker_creates(struct btrfs_worker_thread *worker)
workers->num_workers_starting += 1;
spin_unlock_irqrestore(&workers->lock, flags);
- start_new_worker(workers);
+ btrfs_queue_worker(workers->atomic_worker_start, &start->work);
return;
out:
+ kfree(start);
spin_unlock_irqrestore(&workers->lock, flags);
}
@@ -462,56 +456,55 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max,
* starts new worker threads. This does not enforce the max worker
* count in case you need to temporarily go past it.
*/
-static int __btrfs_start_workers(struct btrfs_workers *workers,
- int num_workers)
+static int __btrfs_start_workers(struct btrfs_workers *workers)
{
struct btrfs_worker_thread *worker;
int ret = 0;
- int i;
- for (i = 0; i < num_workers; i++) {
- worker = kzalloc(sizeof(*worker), GFP_NOFS);
- if (!worker) {
- ret = -ENOMEM;
- goto fail;
- }
+ worker = kzalloc(sizeof(*worker), GFP_NOFS);
+ if (!worker) {
+ ret = -ENOMEM;
+ goto fail;
+ }
- INIT_LIST_HEAD(&worker->pending);
- INIT_LIST_HEAD(&worker->prio_pending);
- INIT_LIST_HEAD(&worker->worker_list);
- spin_lock_init(&worker->lock);
-
- atomic_set(&worker->num_pending, 0);
- atomic_set(&worker->refs, 1);
- worker->workers = workers;
- worker->task = kthread_run(worker_loop, worker,
- "btrfs-%s-%d", workers->name,
- workers->num_workers + i);
- if (IS_ERR(worker->task)) {
- ret = PTR_ERR(worker->task);
- kfree(worker);
- goto fail;
- }
- spin_lock_irq(&workers->lock);
- list_add_tail(&worker->worker_list, &workers->idle_list);
- worker->idle = 1;
- workers->num_workers++;
- workers->num_workers_starting--;
- WARN_ON(workers->num_workers_starting < 0);
- spin_unlock_irq(&workers->lock);
+ INIT_LIST_HEAD(&worker->pending);
+ INIT_LIST_HEAD(&worker->prio_pending);
+ INIT_LIST_HEAD(&worker->worker_list);
+ spin_lock_init(&worker->lock);
+
+ atomic_set(&worker->num_pending, 0);
+ atomic_set(&worker->refs, 1);
+ worker->workers = workers;
+ worker->task = kthread_run(worker_loop, worker,
+ "btrfs-%s-%d", workers->name,
+ workers->num_workers + 1);
+ if (IS_ERR(worker->task)) {
+ ret = PTR_ERR(worker->task);
+ kfree(worker);
+ goto fail;
}
+ spin_lock_irq(&workers->lock);
+ list_add_tail(&worker->worker_list, &workers->idle_list);
+ worker->idle = 1;
+ workers->num_workers++;
+ workers->num_workers_starting--;
+ WARN_ON(workers->num_workers_starting < 0);
+ spin_unlock_irq(&workers->lock);
+
return 0;
fail:
- btrfs_stop_workers(workers);
+ spin_lock_irq(&workers->lock);
+ workers->num_workers_starting--;
+ spin_unlock_irq(&workers->lock);
return ret;
}
-int btrfs_start_workers(struct btrfs_workers *workers, int num_workers)
+int btrfs_start_workers(struct btrfs_workers *workers)
{
spin_lock_irq(&workers->lock);
- workers->num_workers_starting += num_workers;
+ workers->num_workers_starting++;
spin_unlock_irq(&workers->lock);
- return __btrfs_start_workers(workers, num_workers);
+ return __btrfs_start_workers(workers);
}
/*
@@ -568,6 +561,7 @@ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers)
struct btrfs_worker_thread *worker;
unsigned long flags;
struct list_head *fallback;
+ int ret;
again:
spin_lock_irqsave(&workers->lock, flags);
@@ -584,7 +578,9 @@ again:
workers->num_workers_starting++;
spin_unlock_irqrestore(&workers->lock, flags);
/* we're below the limit, start another worker */
- __btrfs_start_workers(workers, 1);
+ ret = __btrfs_start_workers(workers);
+ if (ret)
+ goto fallback;
goto again;
}
}
@@ -665,7 +661,7 @@ void btrfs_set_work_high_prio(struct btrfs_work *work)
/*
* places a struct btrfs_work into the pending queue of one of the kthreads
*/
-int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
+void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
{
struct btrfs_worker_thread *worker;
unsigned long flags;
@@ -673,7 +669,7 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
/* don't requeue something already on a list */
if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
- goto out;
+ return;
worker = find_worker(workers);
if (workers->ordered) {
@@ -712,7 +708,4 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
if (wake)
wake_up_process(worker->task);
spin_unlock_irqrestore(&worker->lock, flags);
-
-out:
- return 0;
}