btrfs: Cleanup the old btrfs_worker.

Since all the btrfs_worker is replaced with the newly created
btrfs_workqueue, the old codes can be easily remove.

Signed-off-by: Quwenruo <quwenruo@cn.fujitsu.com>
Tested-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>

5 files changed, 3 insertions, 825 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 977bce2ec887..2a5f383c3636 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -25,714 +25,13 @@
 #include <linux/workqueue.h>
 #include "async-thread.h"
 
-#define WORK_QUEUED_BIT 0
-#define WORK_DONE_BIT 1
-#define WORK_ORDER_DONE_BIT 2
-#define WORK_HIGH_PRIO_BIT 3
+#define WORK_DONE_BIT 0
+#define WORK_ORDER_DONE_BIT 1
+#define WORK_HIGH_PRIO_BIT 2
 
 #define NO_THRESHOLD (-1)
 #define DFT_THRESHOLD (32)
 
-/*
- * container for the kthread task pointer and the list of pending work
- * One of these is allocated per thread.
- */
-struct btrfs_worker_thread {
-        /* pool we belong to */
-        struct btrfs_workers *workers;
-
-        /* list of struct btrfs_work that are waiting for service */
-        struct list_head pending;
-        struct list_head prio_pending;
-
-        /* list of worker threads from struct btrfs_workers */
-        struct list_head worker_list;
-
-        /* kthread */
-        struct task_struct *task;
-
-        /* number of things on the pending list */
-        atomic_t num_pending;
-
-        /* reference counter for this struct */
-        atomic_t refs;
-
-        unsigned long sequence;
-
-        /* protects the pending list. */
-        spinlock_t lock;
-
-        /* set to non-zero when this thread is already awake and kicking */
-        int working;
-
-        /* are we currently idle */
-        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,
- * and so it may not make progress until after our btrfs worker threads
- * process all of the pending work structs in their queue
- *
- * This means we can't use btrfs_start_workers from inside a btrfs worker
- * thread that is used as part of cleaning dirty memory, which pretty much
- * involves all of the worker threads.
- *
- * Instead we have a helper queue who never has more than one thread
- * where we scheduler thread start operations.  This worker_start struct
- * is used to contain the work and hold a pointer to the queue that needs
- * another worker.
- */
-struct worker_start {
-        struct btrfs_work work;
-        struct btrfs_workers *queue;
-};
-
-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);
-        kfree(start);
-}
-
-/*
- * helper function to move a thread onto the idle list after it
- * has finished some requests.
- */
-static void check_idle_worker(struct btrfs_worker_thread *worker)
-{
-        if (!worker->idle && atomic_read(&worker->num_pending) <
-            worker->workers->idle_thresh / 2) {
-                unsigned long flags;
-                spin_lock_irqsave(&worker->workers->lock, flags);
-                worker->idle = 1;
-
-                /* the list may be empty if the worker is just starting */
-                if (!list_empty(&worker->worker_list) &&
-                    !worker->workers->stopping) {
-                        list_move(&worker->worker_list,
-                                 &worker->workers->idle_list);
-                }
-                spin_unlock_irqrestore(&worker->workers->lock, flags);
-        }
-}
-
-/*
- * helper function to move a thread off the idle list after new
- * pending work is added.
- */
-static void check_busy_worker(struct btrfs_worker_thread *worker)
-{
-        if (worker->idle && atomic_read(&worker->num_pending) >=
-            worker->workers->idle_thresh) {
-                unsigned long flags;
-                spin_lock_irqsave(&worker->workers->lock, flags);
-                worker->idle = 0;
-
-                if (!list_empty(&worker->worker_list) &&
-                    !worker->workers->stopping) {
-                        list_move_tail(&worker->worker_list,
-                                      &worker->workers->worker_list);
-                }
-                spin_unlock_irqrestore(&worker->workers->lock, flags);
-        }
-}
-
-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;
-
-        workers->atomic_start_pending = 0;
-        if (workers->num_workers + workers->num_workers_starting >=
-            workers->max_workers)
-                goto out;
-
-        workers->num_workers_starting += 1;
-        spin_unlock_irqrestore(&workers->lock, flags);
-        btrfs_queue_worker(workers->atomic_worker_start, &start->work);
-        return;
-
-out:
-        kfree(start);
-        spin_unlock_irqrestore(&workers->lock, flags);
-}
-
-static noinline void run_ordered_completions(struct btrfs_workers *workers,
-                                            struct btrfs_work *work)
-{
-        if (!workers->ordered)
-                return;
-
-        set_bit(WORK_DONE_BIT, &work->flags);
-
-        spin_lock(&workers->order_lock);
-
-        while (1) {
-                if (!list_empty(&workers->prio_order_list)) {
-                        work = list_entry(workers->prio_order_list.next,
-                                          struct btrfs_work, order_list);
-                } else if (!list_empty(&workers->order_list)) {
-                        work = list_entry(workers->order_list.next,
-                                          struct btrfs_work, order_list);
-                } else {
-                        break;
-                }
-                if (!test_bit(WORK_DONE_BIT, &work->flags))
-                        break;
-
-                /* we are going to call the ordered done function, but
-                 * we leave the work item on the list as a barrier so
-                 * that later work items that are done don't have their
-                 * functions called before this one returns
-                 */
-                if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
-                        break;
-
-                spin_unlock(&workers->order_lock);
-
-                work->ordered_func(work);
-
-                /* now take the lock again and drop our item from the list */
-                spin_lock(&workers->order_lock);
-                list_del(&work->order_list);
-                spin_unlock(&workers->order_lock);
-
-                /*
-                 * we don't want to call the ordered free functions
-                 * with the lock held though
-                 */
-                work->ordered_free(work);
-                spin_lock(&workers->order_lock);
-        }
-
-        spin_unlock(&workers->order_lock);
-}
-
-static void put_worker(struct btrfs_worker_thread *worker)
-{
-        if (atomic_dec_and_test(&worker->refs))
-                kfree(worker);
-}
-
-static int try_worker_shutdown(struct btrfs_worker_thread *worker)
-{
-        int freeit = 0;
-
-        spin_lock_irq(&worker->lock);
-        spin_lock(&worker->workers->lock);
-        if (worker->workers->num_workers > 1 &&
-            worker->idle &&
-            !worker->working &&
-            !list_empty(&worker->worker_list) &&
-            list_empty(&worker->prio_pending) &&
-            list_empty(&worker->pending) &&
-            atomic_read(&worker->num_pending) == 0) {
-                freeit = 1;
-                list_del_init(&worker->worker_list);
-                worker->workers->num_workers--;
-        }
-        spin_unlock(&worker->workers->lock);
-        spin_unlock_irq(&worker->lock);
-
-        if (freeit)
-                put_worker(worker);
-        return freeit;
-}
-
-static struct btrfs_work *get_next_work(struct btrfs_worker_thread *worker,
-                                        struct list_head *prio_head,
-                                        struct list_head *head)
-{
-        struct btrfs_work *work = NULL;
-        struct list_head *cur = NULL;
-
-        if (!list_empty(prio_head)) {
-                cur = prio_head->next;
-                goto out;
-        }
-
-        smp_mb();
-        if (!list_empty(&worker->prio_pending))
-                goto refill;
-
-        if (!list_empty(head)) {
-                cur = head->next;
-                goto out;
-        }
-
-refill:
-        spin_lock_irq(&worker->lock);
-        list_splice_tail_init(&worker->prio_pending, prio_head);
-        list_splice_tail_init(&worker->pending, head);
-
-        if (!list_empty(prio_head))
-                cur = prio_head->next;
-        else if (!list_empty(head))
-                cur = head->next;
-        spin_unlock_irq(&worker->lock);
-
-        if (!cur)
-                goto out_fail;
-
-out:
-        work = list_entry(cur, struct btrfs_work, list);
-
-out_fail:
-        return work;
-}
-
-/*
- * main loop for servicing work items
- */
-static int worker_loop(void *arg)
-{
-        struct btrfs_worker_thread *worker = arg;
-        struct list_head head;
-        struct list_head prio_head;
-        struct btrfs_work *work;
-
-        INIT_LIST_HEAD(&head);
-        INIT_LIST_HEAD(&prio_head);
-
-        do {
-again:
-                while (1) {
-
-
-                        work = get_next_work(worker, &prio_head, &head);
-                        if (!work)
-                                break;
-
-                        list_del(&work->list);
-                        clear_bit(WORK_QUEUED_BIT, &work->flags);
-
-                        work->worker = worker;
-
-                        work->func(work);
-
-                        atomic_dec(&worker->num_pending);
-                        /*
-                         * unless this is an ordered work queue,
-                         * 'work' was probably freed by func above.
-                         */
-                        run_ordered_completions(worker->workers, work);
-
-                        check_pending_worker_creates(worker);
-                        cond_resched();
-                }
-
-                spin_lock_irq(&worker->lock);
-                check_idle_worker(worker);
-
-                if (freezing(current)) {
-                        worker->working = 0;
-                        spin_unlock_irq(&worker->lock);
-                        try_to_freeze();
-                } else {
-                        spin_unlock_irq(&worker->lock);
-                        if (!kthread_should_stop()) {
-                                cpu_relax();
-                                /*
-                                 * we've dropped the lock, did someone else
-                                 * jump_in?
-                                 */
-                                smp_mb();
-                                if (!list_empty(&worker->pending) ||
-                                    !list_empty(&worker->prio_pending))
-                                        continue;
-
-                                /*
-                                 * this short schedule allows more work to
-                                 * come in without the queue functions
-                                 * needing to go through wake_up_process()
-                                 *
-                                 * worker->working is still 1, so nobody
-                                 * is going to try and wake us up
-                                 */
-                                schedule_timeout(1);
-                                smp_mb();
-                                if (!list_empty(&worker->pending) ||
-                                    !list_empty(&worker->prio_pending))
-                                        continue;
-
-                                if (kthread_should_stop())
-                                        break;
-
-                                /* still no more work?, sleep for real */
-                                spin_lock_irq(&worker->lock);
-                                set_current_state(TASK_INTERRUPTIBLE);
-                                if (!list_empty(&worker->pending) ||
-                                    !list_empty(&worker->prio_pending)) {
-                                        spin_unlock_irq(&worker->lock);
-                                        set_current_state(TASK_RUNNING);
-                                        goto again;
-                                }
-
-                                /*
-                                 * this makes sure we get a wakeup when someone
-                                 * adds something new to the queue
-                                 */
-                                worker->working = 0;
-                                spin_unlock_irq(&worker->lock);
-
-                                if (!kthread_should_stop()) {
-                                        schedule_timeout(HZ * 120);
-                                        if (!worker->working &&
-                                            try_worker_shutdown(worker)) {
-                                                return 0;
-                                        }
-                                }
-                        }
-                        __set_current_state(TASK_RUNNING);
-                }
-        } while (!kthread_should_stop());
-        return 0;
-}
-
-/*
- * this will wait for all the worker threads to shutdown
- */
-void btrfs_stop_workers(struct btrfs_workers *workers)
-{
-        struct list_head *cur;
-        struct btrfs_worker_thread *worker;
-        int can_stop;
-
-        spin_lock_irq(&workers->lock);
-        workers->stopping = 1;
-        list_splice_init(&workers->idle_list, &workers->worker_list);
-        while (!list_empty(&workers->worker_list)) {
-                cur = workers->worker_list.next;
-                worker = list_entry(cur, struct btrfs_worker_thread,
-                                    worker_list);
-
-                atomic_inc(&worker->refs);
-                workers->num_workers -= 1;
-                if (!list_empty(&worker->worker_list)) {
-                        list_del_init(&worker->worker_list);
-                        put_worker(worker);
-                        can_stop = 1;
-                } else
-                        can_stop = 0;
-                spin_unlock_irq(&workers->lock);
-                if (can_stop)
-                        kthread_stop(worker->task);
-                spin_lock_irq(&workers->lock);
-                put_worker(worker);
-        }
-        spin_unlock_irq(&workers->lock);
-}
-
-/*
- * simple init on struct btrfs_workers
- */
-void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max,
-                        struct btrfs_workers *async_helper)
-{
-        workers->num_workers = 0;
-        workers->num_workers_starting = 0;
-        INIT_LIST_HEAD(&workers->worker_list);
-        INIT_LIST_HEAD(&workers->idle_list);
-        INIT_LIST_HEAD(&workers->order_list);
-        INIT_LIST_HEAD(&workers->prio_order_list);
-        spin_lock_init(&workers->lock);
-        spin_lock_init(&workers->order_lock);
-        workers->max_workers = max;
-        workers->idle_thresh = 32;
-        workers->name = name;
-        workers->ordered = 0;
-        workers->atomic_start_pending = 0;
-        workers->atomic_worker_start = async_helper;
-        workers->stopping = 0;
-}
-
-/*
- * 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)
-{
-        struct btrfs_worker_thread *worker;
-        int ret = 0;
-
-        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_create(worker_loop, worker,
-                                      "btrfs-%s-%d", workers->name,
-                                      workers->num_workers + 1);
-        if (IS_ERR(worker->task)) {
-                ret = PTR_ERR(worker->task);
-                goto fail;
-        }
-
-        spin_lock_irq(&workers->lock);
-        if (workers->stopping) {
-                spin_unlock_irq(&workers->lock);
-                ret = -EINVAL;
-                goto fail_kthread;
-        }
-        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);
-
-        wake_up_process(worker->task);
-        return 0;
-
-fail_kthread:
-        kthread_stop(worker->task);
-fail:
-        kfree(worker);
-        spin_lock_irq(&workers->lock);
-        workers->num_workers_starting--;
-        spin_unlock_irq(&workers->lock);
-        return ret;
-}
-
-int btrfs_start_workers(struct btrfs_workers *workers)
-{
-        spin_lock_irq(&workers->lock);
-        workers->num_workers_starting++;
-        spin_unlock_irq(&workers->lock);
-        return __btrfs_start_workers(workers);
-}
-
-/*
- * run through the list and find a worker thread that doesn't have a lot
- * to do right now.  This can return null if we aren't yet at the thread
- * count limit and all of the threads are busy.
- */
-static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers)
-{
-        struct btrfs_worker_thread *worker;
-        struct list_head *next;
-        int enforce_min;
-
-        enforce_min = (workers->num_workers + workers->num_workers_starting) <
-                workers->max_workers;
-
-        /*
-         * if we find an idle thread, don't move it to the end of the
-         * idle list.  This improves the chance that the next submission
-         * will reuse the same thread, and maybe catch it while it is still
-         * working
-         */
-        if (!list_empty(&workers->idle_list)) {
-                next = workers->idle_list.next;
-                worker = list_entry(next, struct btrfs_worker_thread,
-                                    worker_list);
-                return worker;
-        }
-        if (enforce_min || list_empty(&workers->worker_list))
-                return NULL;
-
-        /*
-         * if we pick a busy task, move the task to the end of the list.
-         * hopefully this will keep things somewhat evenly balanced.
-         * Do the move in batches based on the sequence number.  This groups
-         * requests submitted at roughly the same time onto the same worker.
-         */
-        next = workers->worker_list.next;
-        worker = list_entry(next, struct btrfs_worker_thread, worker_list);
-        worker->sequence++;
-
-        if (worker->sequence % workers->idle_thresh == 0)
-                list_move_tail(next, &workers->worker_list);
-        return worker;
-}
-
-/*
- * selects a worker thread to take the next job.  This will either find
- * an idle worker, start a new worker up to the max count, or just return
- * one of the existing busy workers.
- */
-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;
-
-        spin_lock_irqsave(&workers->lock, flags);
-again:
-        worker = next_worker(workers);
-
-        if (!worker) {
-                if (workers->num_workers + workers->num_workers_starting >=
-                    workers->max_workers) {
-                        goto fallback;
-                } else if (workers->atomic_worker_start) {
-                        workers->atomic_start_pending = 1;
-                        goto fallback;
-                } else {
-                        workers->num_workers_starting++;
-                        spin_unlock_irqrestore(&workers->lock, flags);
-                        /* we're below the limit, start another worker */
-                        ret = __btrfs_start_workers(workers);
-                        spin_lock_irqsave(&workers->lock, flags);
-                        if (ret)
-                                goto fallback;
-                        goto again;
-                }
-        }
-        goto found;
-
-fallback:
-        fallback = NULL;
-        /*
-         * we have failed to find any workers, just
-         * return the first one we can find.
-         */
-        if (!list_empty(&workers->worker_list))
-                fallback = workers->worker_list.next;
-        if (!list_empty(&workers->idle_list))
-                fallback = workers->idle_list.next;
-        BUG_ON(!fallback);
-        worker = list_entry(fallback,
-                  struct btrfs_worker_thread, worker_list);
-found:
-        /*
-         * this makes sure the worker doesn't exit before it is placed
-         * onto a busy/idle list
-         */
-        atomic_inc(&worker->num_pending);
-        spin_unlock_irqrestore(&workers->lock, flags);
-        return worker;
-}
-
-/*
- * btrfs_requeue_work just puts the work item back on the tail of the list
- * it was taken from.  It is intended for use with long running work functions
- * that make some progress and want to give the cpu up for others.
- */
-void btrfs_requeue_work(struct btrfs_work *work)
-{
-        struct btrfs_worker_thread *worker = work->worker;
-        unsigned long flags;
-        int wake = 0;
-
-        if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
-                return;
-
-        spin_lock_irqsave(&worker->lock, flags);
-        if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
-                list_add_tail(&work->list, &worker->prio_pending);
-        else
-                list_add_tail(&work->list, &worker->pending);
-        atomic_inc(&worker->num_pending);
-
-        /* by definition we're busy, take ourselves off the idle
-         * list
-         */
-        if (worker->idle) {
-                spin_lock(&worker->workers->lock);
-                worker->idle = 0;
-                list_move_tail(&worker->worker_list,
-                              &worker->workers->worker_list);
-                spin_unlock(&worker->workers->lock);
-        }
-        if (!worker->working) {
-                wake = 1;
-                worker->working = 1;
-        }
-
-        if (wake)
-                wake_up_process(worker->task);
-        spin_unlock_irqrestore(&worker->lock, flags);
-}
-
-void btrfs_set_work_high_prio(struct btrfs_work *work)
-{
-        set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
-}
-
-/*
- * places a struct btrfs_work into the pending queue of one of the kthreads
- */
-void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
-{
-        struct btrfs_worker_thread *worker;
-        unsigned long flags;
-        int wake = 0;
-
-        /* don't requeue something already on a list */
-        if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
-                return;
-
-        worker = find_worker(workers);
-        if (workers->ordered) {
-                /*
-                 * you're not allowed to do ordered queues from an
-                 * interrupt handler
-                 */
-                spin_lock(&workers->order_lock);
-                if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) {
-                        list_add_tail(&work->order_list,
-                                      &workers->prio_order_list);
-                } else {
-                        list_add_tail(&work->order_list, &workers->order_list);
-                }
-                spin_unlock(&workers->order_lock);
-        } else {
-                INIT_LIST_HEAD(&work->order_list);
-        }
-
-        spin_lock_irqsave(&worker->lock, flags);
-
-        if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
-                list_add_tail(&work->list, &worker->prio_pending);
-        else
-                list_add_tail(&work->list, &worker->pending);
-        check_busy_worker(worker);
-
-        /*
-         * avoid calling into wake_up_process if this thread has already
-         * been kicked
-         */
-        if (!worker->working)
-                wake = 1;
-        worker->working = 1;
-
-        if (wake)
-                wake_up_process(worker->task);
-        spin_unlock_irqrestore(&worker->lock, flags);
-}
-
 struct __btrfs_workqueue_struct {
         struct workqueue_struct *normal_wq;
         /* List head pointing to ordered work list */
diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h
index 3129d8a6128b..ab05904f791c 100644
--- a/fs/btrfs/async-thread.h
+++ b/fs/btrfs/async-thread.h
@@ -20,106 +20,6 @@
 #ifndef __BTRFS_ASYNC_THREAD_
 #define __BTRFS_ASYNC_THREAD_
 
-struct btrfs_worker_thread;
-
-/*
- * This is similar to a workqueue, but it is meant to spread the operations
- * across all available cpus instead of just the CPU that was used to
- * queue the work.  There is also some batching introduced to try and
- * cut down on context switches.
- *
- * By default threads are added on demand up to 2 * the number of cpus.
- * Changing struct btrfs_workers->max_workers is one way to prevent
- * demand creation of kthreads.
- *
- * the basic model of these worker threads is to embed a btrfs_work
- * structure in your own data struct, and use container_of in a
- * work function to get back to your data struct.
- */
-struct btrfs_work {
-        /*
-         * func should be set to the function you want called
-         * your work struct is passed as the only arg
-         *
-         * ordered_func must be set for work sent to an ordered work queue,
-         * and it is called to complete a given work item in the same
-         * order they were sent to the queue.
-         */
-        void (*func)(struct btrfs_work *work);
-        void (*ordered_func)(struct btrfs_work *work);
-        void (*ordered_free)(struct btrfs_work *work);
-
-        /*
-         * flags should be set to zero.  It is used to make sure the
-         * struct is only inserted once into the list.
-         */
-        unsigned long flags;
-
-        /* don't touch these */
-        struct btrfs_worker_thread *worker;
-        struct list_head list;
-        struct list_head order_list;
-};
-
-struct btrfs_workers {
-        /* current number of running workers */
-        int num_workers;
-
-        int num_workers_starting;
-
-        /* max number of workers allowed.  changed by btrfs_start_workers */
-        int max_workers;
-
-        /* once a worker has this many requests or fewer, it is idle */
-        int idle_thresh;
-
-        /* force completions in the order they were queued */
-        int ordered;
-
-        /* more workers required, but in an interrupt handler */
-        int atomic_start_pending;
-
-        /*
-         * are we allowed to sleep while starting workers or are we required
-         * to start them at a later time?  If we can't sleep, this indicates
-         * which queue we need to use to schedule thread creation.
-         */
-        struct btrfs_workers *atomic_worker_start;
-
-        /* list with all the work threads.  The workers on the idle thread
-         * may be actively servicing jobs, but they haven't yet hit the
-         * idle thresh limit above.
-         */
-        struct list_head worker_list;
-        struct list_head idle_list;
-
-        /*
-         * when operating in ordered mode, this maintains the list
-         * of work items waiting for completion
-         */
-        struct list_head order_list;
-        struct list_head prio_order_list;
-
-        /* lock for finding the next worker thread to queue on */
-        spinlock_t lock;
-
-        /* lock for the ordered lists */
-        spinlock_t order_lock;
-
-        /* extra name for this worker, used for current->name */
-        char *name;
-
-        int stopping;
-};
-
-void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work);
-int btrfs_start_workers(struct btrfs_workers *workers);
-void btrfs_stop_workers(struct btrfs_workers *workers);
-void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max,
-                        struct btrfs_workers *async_starter);
-void btrfs_requeue_work(struct btrfs_work *work);
-void btrfs_set_work_high_prio(struct btrfs_work *work);
-
 struct btrfs_workqueue_struct;
 /* Internal use only */
 struct __btrfs_workqueue_struct;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a98f86ac187e..5a8c77a441ba 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1504,7 +1504,6 @@ struct btrfs_fs_info {
          * A third pool does submit_bio to avoid deadlocking with the other
          * two
          */
-        struct btrfs_workers generic_worker;
         struct btrfs_workqueue_struct *workers;
         struct btrfs_workqueue_struct *delalloc_workers;
         struct btrfs_workqueue_struct *flush_workers;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 9aaf9c309b54..c80d9507171c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1994,7 +1994,6 @@ static noinline int next_root_backup(struct btrfs_fs_info *info,
 /* helper to cleanup workers */
 static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
 {
-        btrfs_stop_workers(&fs_info->generic_worker);
         btrfs_destroy_workqueue(fs_info->fixup_workers);
         btrfs_destroy_workqueue(fs_info->delalloc_workers);
         btrfs_destroy_workqueue(fs_info->workers);
@@ -2472,8 +2471,6 @@ int open_ctree(struct super_block *sb,
         }
 
         max_active = fs_info->thread_pool_size;
-        btrfs_init_workers(&fs_info->generic_worker,
-                           "genwork", 1, NULL);
 
         fs_info->workers =
                 btrfs_alloc_workqueue("worker", flags | WQ_HIGHPRI,
@@ -2526,15 +2523,6 @@ int open_ctree(struct super_block *sb,
         fs_info->qgroup_rescan_workers =
                 btrfs_alloc_workqueue("qgroup-rescan", flags, 1, 0);
 
-        /*
-         * btrfs_start_workers can really only fail because of ENOMEM so just
-         * return -ENOMEM if any of these fail.
-         */
-        ret = btrfs_start_workers(&fs_info->generic_worker);
-        if (ret) {
-                err = -ENOMEM;
-                goto fail_sb_buffer;
-        }
         if (!(fs_info->workers && fs_info->delalloc_workers &&
               fs_info->submit_workers && fs_info->flush_workers &&
               fs_info->endio_workers && fs_info->endio_meta_workers &&
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index aed1e11060a0..d4878ddba87a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1305,13 +1305,6 @@ error_fs_info:
         return ERR_PTR(error);
 }
 
-static void btrfs_set_max_workers(struct btrfs_workers *workers, int new_limit)
-{
-        spin_lock_irq(&workers->lock);
-        workers->max_workers = new_limit;
-        spin_unlock_irq(&workers->lock);
-}
-
 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
                                      int new_pool_size, int old_pool_size)
 {
@@ -1323,7 +1316,6 @@ static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
         btrfs_info(fs_info, "resize thread pool %d -> %d",
                old_pool_size, new_pool_size);
 
-        btrfs_set_max_workers(&fs_info->generic_worker, new_pool_size);
         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);