From c1955ce32fdb0877b7a1b22feb2669358f65be76 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sat, 19 Jun 2010 23:08:06 +0200 Subject: 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 Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 4 +-- include/linux/backing-dev.h | 5 +-- mm/backing-dev.c | 83 ++++++++++++++++----------------------------- 3 files changed, 32 insertions(+), 60 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index d5be1693ac9..d67989b8ba4 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -73,9 +73,9 @@ static void bdi_queue_work(struct backing_dev_info *bdi, * If the default thread isn't there, make sure we add it. When * it gets created and wakes up, we'll run this work. */ - if (unlikely(list_empty_careful(&bdi->wb_list))) + if (unlikely(!bdi->wb.task)) { wake_up_process(default_backing_dev_info.wb.task); - else { + } else { struct bdi_writeback *wb = &bdi->wb; if (wb->task) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index e9aec0d099d..50f14614616 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -45,8 +45,6 @@ enum bdi_stat_item { #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) struct bdi_writeback { - struct list_head list; /* hangs off the bdi */ - struct backing_dev_info *bdi; /* our parent bdi */ unsigned int nr; @@ -80,8 +78,7 @@ struct backing_dev_info { unsigned int max_ratio, max_prop_frac; struct bdi_writeback wb; /* default writeback info for this bdi */ - spinlock_t wb_lock; /* protects update side of wb_list */ - struct list_head wb_list; /* the flusher threads hanging off this bdi */ + spinlock_t wb_lock; /* protects work_list */ struct list_head work_list; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 123bcef13e5..6c2a09c8922 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -65,28 +65,21 @@ static void bdi_debug_init(void) static int bdi_debug_stats_show(struct seq_file *m, void *v) { struct backing_dev_info *bdi = m->private; - struct bdi_writeback *wb; + struct bdi_writeback *wb = &bdi->wb; unsigned long background_thresh; unsigned long dirty_thresh; unsigned long bdi_thresh; unsigned long nr_dirty, nr_io, nr_more_io, nr_wb; struct inode *inode; - /* - * inode lock is enough here, the bdi->wb_list is protected by - * RCU on the reader side - */ nr_wb = nr_dirty = nr_io = nr_more_io = 0; spin_lock(&inode_lock); - list_for_each_entry(wb, &bdi->wb_list, list) { - nr_wb++; - list_for_each_entry(inode, &wb->b_dirty, i_list) - nr_dirty++; - list_for_each_entry(inode, &wb->b_io, i_list) - nr_io++; - list_for_each_entry(inode, &wb->b_more_io, i_list) - nr_more_io++; - } + list_for_each_entry(inode, &wb->b_dirty, i_list) + nr_dirty++; + list_for_each_entry(inode, &wb->b_io, i_list) + nr_io++; + list_for_each_entry(inode, &wb->b_more_io, i_list) + nr_more_io++; spin_unlock(&inode_lock); get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); @@ -98,19 +91,16 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) "BdiDirtyThresh: %8lu kB\n" "DirtyThresh: %8lu kB\n" "BackgroundThresh: %8lu kB\n" - "WritebackThreads: %8lu\n" "b_dirty: %8lu\n" "b_io: %8lu\n" "b_more_io: %8lu\n" "bdi_list: %8u\n" - "state: %8lx\n" - "wb_list: %8u\n", + "state: %8lx\n", (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), K(bdi_thresh), K(dirty_thresh), - K(background_thresh), nr_wb, nr_dirty, nr_io, nr_more_io, - !list_empty(&bdi->bdi_list), bdi->state, - !list_empty(&bdi->wb_list)); + K(background_thresh), nr_dirty, nr_io, nr_more_io, + !list_empty(&bdi->bdi_list), bdi->state); #undef K return 0; @@ -270,24 +260,6 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) INIT_LIST_HEAD(&wb->b_more_io); } -static void bdi_task_init(struct backing_dev_info *bdi, - struct bdi_writeback *wb) -{ - struct task_struct *tsk = current; - - spin_lock(&bdi->wb_lock); - list_add_tail_rcu(&wb->list, &bdi->wb_list); - spin_unlock(&bdi->wb_lock); - - tsk->flags |= PF_FLUSHER | PF_SWAPWRITE; - set_freezable(); - - /* - * Our parent may run at a different priority, just set us to normal - */ - set_user_nice(tsk, 0); -} - static int bdi_start_fn(void *ptr) { struct bdi_writeback *wb = ptr; @@ -301,7 +273,13 @@ static int bdi_start_fn(void *ptr) list_add_rcu(&bdi->bdi_list, &bdi_list); spin_unlock_bh(&bdi_lock); - bdi_task_init(bdi, wb); + current->flags |= PF_FLUSHER | PF_SWAPWRITE; + set_freezable(); + + /* + * Our parent may run at a different priority, just set us to normal + */ + set_user_nice(current, 0); /* * Clear pending bit and wakeup anybody waiting to tear us down @@ -312,12 +290,7 @@ static int bdi_start_fn(void *ptr) ret = bdi_writeback_task(wb); - /* - * Remove us from the list - */ - spin_lock(&bdi->wb_lock); - list_del_rcu(&wb->list); - spin_unlock(&bdi->wb_lock); + wb->task = NULL; /* * Flush any work that raced with us exiting. No new work @@ -326,7 +299,6 @@ static int bdi_start_fn(void *ptr) if (!list_empty(&bdi->work_list)) wb_do_writeback(wb, 1); - wb->task = NULL; return ret; } @@ -391,7 +363,13 @@ static int bdi_forker_task(void *ptr) { struct bdi_writeback *me = ptr; - bdi_task_init(me->bdi, me); + current->flags |= PF_FLUSHER | PF_SWAPWRITE; + set_freezable(); + + /* + * Our parent may run at a different priority, just set us to normal + */ + set_user_nice(current, 0); for (;;) { struct backing_dev_info *bdi, *tmp; @@ -598,8 +576,6 @@ EXPORT_SYMBOL(bdi_register_dev); */ static void bdi_wb_shutdown(struct backing_dev_info *bdi) { - struct bdi_writeback *wb; - if (!bdi_cap_writeback_dirty(bdi)) return; @@ -615,14 +591,14 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi) bdi_remove_from_list(bdi); /* - * Finally, kill the kernel threads. We don't need to be RCU + * Finally, kill the kernel thread. We don't need to be RCU * safe anymore, since the bdi is gone from visibility. Force * unfreeze of the thread before calling kthread_stop(), otherwise * it would never exet if it is currently stuck in the refrigerator. */ - list_for_each_entry(wb, &bdi->wb_list, list) { - thaw_process(wb->task); - kthread_stop(wb->task); + if (bdi->wb.task) { + thaw_process(bdi->wb.task); + kthread_stop(bdi->wb.task); } } @@ -667,7 +643,6 @@ int bdi_init(struct backing_dev_info *bdi) spin_lock_init(&bdi->wb_lock); INIT_RCU_HEAD(&bdi->rcu_head); INIT_LIST_HEAD(&bdi->bdi_list); - INIT_LIST_HEAD(&bdi->wb_list); INIT_LIST_HEAD(&bdi->work_list); bdi_wb_init(&bdi->wb, bdi); -- cgit v1.2.3-18-g5258