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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 2010-06-19 23:08:06 +02:00 committed by Jens Axboe
parent 4c4762d10f
commit c1955ce32f
3 changed files with 32 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/fs-writeback.c
View File

@ -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)

5
include/linux/backing-dev.h
View File

@ -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;

83
mm/backing-dev.c
View File

@ -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);