writeback: remove wb_list
The wb_list member of struct backing_device_info always has exactly one element. Just use the direct bdi->wb pointer instead and simplify some code. Also remove bdi_task_init which is now trivial to prepare for the next patch. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Christoph Hellwig
Jens Axboe
Родитель
4c4762d10f
Коммит
c1955ce32f
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@ -73,9 +73,9 @@ static void bdi_queue_work(struct backing_dev_info *bdi,
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* If the default thread isn't there, make sure we add it. When
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* it gets created and wakes up, we'll run this work.
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*/
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if (unlikely(list_empty_careful(&bdi->wb_list)))
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if (unlikely(!bdi->wb.task)) {
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wake_up_process(default_backing_dev_info.wb.task);
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else {
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} else {
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struct bdi_writeback *wb = &bdi->wb;
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if (wb->task)
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@ -45,8 +45,6 @@ enum bdi_stat_item {
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#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
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struct bdi_writeback {
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struct list_head list; /* hangs off the bdi */
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struct backing_dev_info *bdi; /* our parent bdi */
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unsigned int nr;
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@ -80,8 +78,7 @@ struct backing_dev_info {
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unsigned int max_ratio, max_prop_frac;
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struct bdi_writeback wb; /* default writeback info for this bdi */
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spinlock_t wb_lock; /* protects update side of wb_list */
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struct list_head wb_list; /* the flusher threads hanging off this bdi */
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spinlock_t wb_lock; /* protects work_list */
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struct list_head work_list;
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@ -65,28 +65,21 @@ static void bdi_debug_init(void)
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static int bdi_debug_stats_show(struct seq_file *m, void *v)
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{
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struct backing_dev_info *bdi = m->private;
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struct bdi_writeback *wb;
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struct bdi_writeback *wb = &bdi->wb;
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unsigned long background_thresh;
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unsigned long dirty_thresh;
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unsigned long bdi_thresh;
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unsigned long nr_dirty, nr_io, nr_more_io, nr_wb;
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struct inode *inode;
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/*
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* inode lock is enough here, the bdi->wb_list is protected by
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* RCU on the reader side
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*/
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nr_wb = nr_dirty = nr_io = nr_more_io = 0;
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spin_lock(&inode_lock);
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list_for_each_entry(wb, &bdi->wb_list, list) {
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nr_wb++;
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list_for_each_entry(inode, &wb->b_dirty, i_list)
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nr_dirty++;
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list_for_each_entry(inode, &wb->b_io, i_list)
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nr_io++;
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list_for_each_entry(inode, &wb->b_more_io, i_list)
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nr_more_io++;
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}
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list_for_each_entry(inode, &wb->b_dirty, i_list)
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nr_dirty++;
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list_for_each_entry(inode, &wb->b_io, i_list)
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nr_io++;
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list_for_each_entry(inode, &wb->b_more_io, i_list)
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nr_more_io++;
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spin_unlock(&inode_lock);
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get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
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@ -98,19 +91,16 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
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"BdiDirtyThresh: %8lu kB\n"
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"DirtyThresh: %8lu kB\n"
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"BackgroundThresh: %8lu kB\n"
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"WritebackThreads: %8lu\n"
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"b_dirty: %8lu\n"
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"b_io: %8lu\n"
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"b_more_io: %8lu\n"
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"bdi_list: %8u\n"
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"state: %8lx\n"
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"wb_list: %8u\n",
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"state: %8lx\n",
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(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
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(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
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K(bdi_thresh), K(dirty_thresh),
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K(background_thresh), nr_wb, nr_dirty, nr_io, nr_more_io,
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!list_empty(&bdi->bdi_list), bdi->state,
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!list_empty(&bdi->wb_list));
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K(background_thresh), nr_dirty, nr_io, nr_more_io,
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!list_empty(&bdi->bdi_list), bdi->state);
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#undef K
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return 0;
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@ -270,24 +260,6 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
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INIT_LIST_HEAD(&wb->b_more_io);
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}
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static void bdi_task_init(struct backing_dev_info *bdi,
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struct bdi_writeback *wb)
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{
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struct task_struct *tsk = current;
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spin_lock(&bdi->wb_lock);
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list_add_tail_rcu(&wb->list, &bdi->wb_list);
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spin_unlock(&bdi->wb_lock);
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tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
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set_freezable();
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/*
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* Our parent may run at a different priority, just set us to normal
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*/
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set_user_nice(tsk, 0);
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}
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static int bdi_start_fn(void *ptr)
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{
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struct bdi_writeback *wb = ptr;
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@ -301,7 +273,13 @@ static int bdi_start_fn(void *ptr)
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list_add_rcu(&bdi->bdi_list, &bdi_list);
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spin_unlock_bh(&bdi_lock);
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bdi_task_init(bdi, wb);
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current->flags |= PF_FLUSHER | PF_SWAPWRITE;
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set_freezable();
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/*
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* Our parent may run at a different priority, just set us to normal
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*/
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set_user_nice(current, 0);
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/*
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* Clear pending bit and wakeup anybody waiting to tear us down
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@ -312,12 +290,7 @@ static int bdi_start_fn(void *ptr)
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ret = bdi_writeback_task(wb);
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/*
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* Remove us from the list
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*/
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spin_lock(&bdi->wb_lock);
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list_del_rcu(&wb->list);
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spin_unlock(&bdi->wb_lock);
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wb->task = NULL;
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/*
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* Flush any work that raced with us exiting. No new work
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@ -326,7 +299,6 @@ static int bdi_start_fn(void *ptr)
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if (!list_empty(&bdi->work_list))
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wb_do_writeback(wb, 1);
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wb->task = NULL;
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return ret;
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}
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@ -391,7 +363,13 @@ static int bdi_forker_task(void *ptr)
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{
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struct bdi_writeback *me = ptr;
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bdi_task_init(me->bdi, me);
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current->flags |= PF_FLUSHER | PF_SWAPWRITE;
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set_freezable();
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/*
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* Our parent may run at a different priority, just set us to normal
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*/
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set_user_nice(current, 0);
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for (;;) {
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struct backing_dev_info *bdi, *tmp;
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@ -598,8 +576,6 @@ EXPORT_SYMBOL(bdi_register_dev);
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*/
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static void bdi_wb_shutdown(struct backing_dev_info *bdi)
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{
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struct bdi_writeback *wb;
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if (!bdi_cap_writeback_dirty(bdi))
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return;
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@ -615,14 +591,14 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
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bdi_remove_from_list(bdi);
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/*
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* Finally, kill the kernel threads. We don't need to be RCU
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* Finally, kill the kernel thread. We don't need to be RCU
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* safe anymore, since the bdi is gone from visibility. Force
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* unfreeze of the thread before calling kthread_stop(), otherwise
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* it would never exet if it is currently stuck in the refrigerator.
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*/
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list_for_each_entry(wb, &bdi->wb_list, list) {
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thaw_process(wb->task);
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kthread_stop(wb->task);
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if (bdi->wb.task) {
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thaw_process(bdi->wb.task);
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kthread_stop(bdi->wb.task);
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}
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}
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@ -667,7 +643,6 @@ int bdi_init(struct backing_dev_info *bdi)
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spin_lock_init(&bdi->wb_lock);
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INIT_RCU_HEAD(&bdi->rcu_head);
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INIT_LIST_HEAD(&bdi->bdi_list);
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INIT_LIST_HEAD(&bdi->wb_list);
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INIT_LIST_HEAD(&bdi->work_list);
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bdi_wb_init(&bdi->wb, bdi);
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