![David Sterba](/assets/img/avatar_default.png)
Unlikely is implicit for NULL checks of pointers. Signed-off-by: David Sterba <dsterba@suse.cz>
366 lines
9.1 KiB
C
366 lines
9.1 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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* Copyright (C) 2014 Fujitsu. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/kthread.h>
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#include <linux/slab.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/freezer.h>
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#include "async-thread.h"
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#include "ctree.h"
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#define WORK_DONE_BIT 0
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#define WORK_ORDER_DONE_BIT 1
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#define WORK_HIGH_PRIO_BIT 2
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#define NO_THRESHOLD (-1)
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#define DFT_THRESHOLD (32)
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struct __btrfs_workqueue {
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struct workqueue_struct *normal_wq;
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/* List head pointing to ordered work list */
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struct list_head ordered_list;
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/* Spinlock for ordered_list */
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spinlock_t list_lock;
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/* Thresholding related variants */
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atomic_t pending;
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int max_active;
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int current_max;
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int thresh;
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unsigned int count;
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spinlock_t thres_lock;
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};
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struct btrfs_workqueue {
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struct __btrfs_workqueue *normal;
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struct __btrfs_workqueue *high;
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};
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static void normal_work_helper(struct btrfs_work *work);
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#define BTRFS_WORK_HELPER(name) \
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void btrfs_##name(struct work_struct *arg) \
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{ \
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struct btrfs_work *work = container_of(arg, struct btrfs_work, \
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normal_work); \
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normal_work_helper(work); \
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}
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BTRFS_WORK_HELPER(worker_helper);
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BTRFS_WORK_HELPER(delalloc_helper);
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BTRFS_WORK_HELPER(flush_delalloc_helper);
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BTRFS_WORK_HELPER(cache_helper);
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BTRFS_WORK_HELPER(submit_helper);
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BTRFS_WORK_HELPER(fixup_helper);
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BTRFS_WORK_HELPER(endio_helper);
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BTRFS_WORK_HELPER(endio_meta_helper);
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BTRFS_WORK_HELPER(endio_meta_write_helper);
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BTRFS_WORK_HELPER(endio_raid56_helper);
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BTRFS_WORK_HELPER(endio_repair_helper);
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BTRFS_WORK_HELPER(rmw_helper);
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BTRFS_WORK_HELPER(endio_write_helper);
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BTRFS_WORK_HELPER(freespace_write_helper);
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BTRFS_WORK_HELPER(delayed_meta_helper);
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BTRFS_WORK_HELPER(readahead_helper);
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BTRFS_WORK_HELPER(qgroup_rescan_helper);
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BTRFS_WORK_HELPER(extent_refs_helper);
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BTRFS_WORK_HELPER(scrub_helper);
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BTRFS_WORK_HELPER(scrubwrc_helper);
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BTRFS_WORK_HELPER(scrubnc_helper);
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static struct __btrfs_workqueue *
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__btrfs_alloc_workqueue(const char *name, int flags, int max_active,
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int thresh)
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{
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struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
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if (!ret)
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return NULL;
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ret->max_active = max_active;
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atomic_set(&ret->pending, 0);
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if (thresh == 0)
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thresh = DFT_THRESHOLD;
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/* For low threshold, disabling threshold is a better choice */
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if (thresh < DFT_THRESHOLD) {
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ret->current_max = max_active;
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ret->thresh = NO_THRESHOLD;
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} else {
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ret->current_max = 1;
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ret->thresh = thresh;
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}
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if (flags & WQ_HIGHPRI)
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ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
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ret->max_active,
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"btrfs", name);
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else
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ret->normal_wq = alloc_workqueue("%s-%s", flags,
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ret->max_active, "btrfs",
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name);
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if (!ret->normal_wq) {
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kfree(ret);
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return NULL;
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}
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INIT_LIST_HEAD(&ret->ordered_list);
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spin_lock_init(&ret->list_lock);
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spin_lock_init(&ret->thres_lock);
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trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
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return ret;
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}
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static inline void
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__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
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struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
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int flags,
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int max_active,
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int thresh)
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{
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struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
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if (!ret)
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return NULL;
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ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
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max_active, thresh);
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if (!ret->normal) {
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kfree(ret);
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return NULL;
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}
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if (flags & WQ_HIGHPRI) {
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ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
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thresh);
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if (!ret->high) {
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__btrfs_destroy_workqueue(ret->normal);
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kfree(ret);
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return NULL;
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}
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}
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return ret;
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}
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/*
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* Hook for threshold which will be called in btrfs_queue_work.
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* This hook WILL be called in IRQ handler context,
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* so workqueue_set_max_active MUST NOT be called in this hook
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*/
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static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
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{
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if (wq->thresh == NO_THRESHOLD)
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return;
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atomic_inc(&wq->pending);
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}
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/*
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* Hook for threshold which will be called before executing the work,
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* This hook is called in kthread content.
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* So workqueue_set_max_active is called here.
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*/
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static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
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{
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int new_max_active;
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long pending;
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int need_change = 0;
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if (wq->thresh == NO_THRESHOLD)
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return;
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atomic_dec(&wq->pending);
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spin_lock(&wq->thres_lock);
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/*
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* Use wq->count to limit the calling frequency of
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* workqueue_set_max_active.
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*/
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wq->count++;
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wq->count %= (wq->thresh / 4);
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if (!wq->count)
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goto out;
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new_max_active = wq->current_max;
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/*
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* pending may be changed later, but it's OK since we really
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* don't need it so accurate to calculate new_max_active.
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*/
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pending = atomic_read(&wq->pending);
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if (pending > wq->thresh)
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new_max_active++;
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if (pending < wq->thresh / 2)
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new_max_active--;
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new_max_active = clamp_val(new_max_active, 1, wq->max_active);
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if (new_max_active != wq->current_max) {
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need_change = 1;
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wq->current_max = new_max_active;
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}
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out:
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spin_unlock(&wq->thres_lock);
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if (need_change) {
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workqueue_set_max_active(wq->normal_wq, wq->current_max);
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}
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}
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static void run_ordered_work(struct __btrfs_workqueue *wq)
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{
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struct list_head *list = &wq->ordered_list;
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struct btrfs_work *work;
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spinlock_t *lock = &wq->list_lock;
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unsigned long flags;
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while (1) {
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spin_lock_irqsave(lock, flags);
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if (list_empty(list))
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break;
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work = list_entry(list->next, struct btrfs_work,
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ordered_list);
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if (!test_bit(WORK_DONE_BIT, &work->flags))
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break;
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/*
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* we are going to call the ordered done function, but
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* we leave the work item on the list as a barrier so
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* that later work items that are done don't have their
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* functions called before this one returns
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*/
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if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
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break;
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trace_btrfs_ordered_sched(work);
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spin_unlock_irqrestore(lock, flags);
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work->ordered_func(work);
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/* now take the lock again and drop our item from the list */
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spin_lock_irqsave(lock, flags);
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list_del(&work->ordered_list);
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spin_unlock_irqrestore(lock, flags);
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/*
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* we don't want to call the ordered free functions
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* with the lock held though
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*/
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work->ordered_free(work);
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trace_btrfs_all_work_done(work);
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}
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spin_unlock_irqrestore(lock, flags);
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}
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static void normal_work_helper(struct btrfs_work *work)
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{
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struct __btrfs_workqueue *wq;
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int need_order = 0;
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/*
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* We should not touch things inside work in the following cases:
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* 1) after work->func() if it has no ordered_free
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* Since the struct is freed in work->func().
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* 2) after setting WORK_DONE_BIT
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* The work may be freed in other threads almost instantly.
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* So we save the needed things here.
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*/
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if (work->ordered_func)
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need_order = 1;
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wq = work->wq;
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trace_btrfs_work_sched(work);
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thresh_exec_hook(wq);
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work->func(work);
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if (need_order) {
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set_bit(WORK_DONE_BIT, &work->flags);
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run_ordered_work(wq);
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}
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if (!need_order)
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trace_btrfs_all_work_done(work);
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}
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void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
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btrfs_func_t func,
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btrfs_func_t ordered_func,
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btrfs_func_t ordered_free)
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{
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work->func = func;
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work->ordered_func = ordered_func;
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work->ordered_free = ordered_free;
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INIT_WORK(&work->normal_work, uniq_func);
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INIT_LIST_HEAD(&work->ordered_list);
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work->flags = 0;
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}
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static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
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struct btrfs_work *work)
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{
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unsigned long flags;
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work->wq = wq;
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thresh_queue_hook(wq);
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if (work->ordered_func) {
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spin_lock_irqsave(&wq->list_lock, flags);
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list_add_tail(&work->ordered_list, &wq->ordered_list);
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spin_unlock_irqrestore(&wq->list_lock, flags);
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}
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queue_work(wq->normal_wq, &work->normal_work);
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trace_btrfs_work_queued(work);
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}
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void btrfs_queue_work(struct btrfs_workqueue *wq,
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struct btrfs_work *work)
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{
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struct __btrfs_workqueue *dest_wq;
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if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
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dest_wq = wq->high;
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else
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dest_wq = wq->normal;
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__btrfs_queue_work(dest_wq, work);
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}
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static inline void
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__btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
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{
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destroy_workqueue(wq->normal_wq);
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trace_btrfs_workqueue_destroy(wq);
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kfree(wq);
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}
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void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
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{
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if (!wq)
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return;
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if (wq->high)
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__btrfs_destroy_workqueue(wq->high);
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__btrfs_destroy_workqueue(wq->normal);
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kfree(wq);
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}
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void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
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{
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if (!wq)
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return;
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wq->normal->max_active = max;
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if (wq->high)
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wq->high->max_active = max;
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}
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void btrfs_set_work_high_priority(struct btrfs_work *work)
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{
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set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
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}
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