#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/device.h>
+#include <trace/events/writeback.h>
static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
static int bdi_sync_supers(void *);
static void sync_supers_timer_fn(unsigned long);
-static void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
-
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/seq_file.h>
}
/*
- * kupdated() used to do this. We cannot do it from the bdi_forker_task()
+ * kupdated() used to do this. We cannot do it from the bdi_forker_thread()
* or we risk deadlocking on ->s_umount. The longer term solution would be
* to implement sync_supers_bdi() or similar and simply do it from the
- * bdi writeback tasks individually.
+ * bdi writeback thread individually.
*/
static int bdi_sync_supers(void *unused)
{
bdi_arm_supers_timer();
}
-static int bdi_forker_task(void *ptr)
+static int bdi_forker_thread(void *ptr)
{
struct bdi_writeback *me = ptr;
set_user_nice(current, 0);
for (;;) {
+ bool fork = false;
+ struct task_struct *task;
struct backing_dev_info *bdi, *tmp;
- struct bdi_writeback *wb;
/*
* Temporary measure, we want to make sure we don't see
wb_do_writeback(me, 0);
spin_lock_bh(&bdi_lock);
+ set_current_state(TASK_INTERRUPTIBLE);
/*
* Check if any existing bdi's have dirty data without
* a thread registered. If so, set that up.
*/
list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
+ if (!bdi_cap_writeback_dirty(bdi))
+ continue;
if (bdi->wb.task)
continue;
if (list_empty(&bdi->work_list) &&
!bdi_has_dirty_io(bdi))
continue;
- bdi_add_default_flusher_task(bdi);
+ WARN(!test_bit(BDI_registered, &bdi->state),
+ "bdi %p/%s is not registered!\n", bdi, bdi->name);
+
+ list_del_rcu(&bdi->bdi_list);
+ fork = true;
+ break;
}
+ spin_unlock_bh(&bdi_lock);
- set_current_state(TASK_INTERRUPTIBLE);
+ /* Keep working if default bdi still has things to do */
+ if (!list_empty(&me->bdi->work_list))
+ __set_current_state(TASK_RUNNING);
- if (list_empty(&bdi_pending_list)) {
+ if (!fork) {
unsigned long wait;
- spin_unlock_bh(&bdi_lock);
wait = msecs_to_jiffies(dirty_writeback_interval * 10);
if (wait)
schedule_timeout(wait);
__set_current_state(TASK_RUNNING);
/*
- * This is our real job - check for pending entries in
- * bdi_pending_list, and create the tasks that got added
+ * Set the pending bit - if someone will try to unregister this
+ * bdi - it'll wait on this bit.
*/
- bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
- bdi_list);
- list_del_init(&bdi->bdi_list);
- spin_unlock_bh(&bdi_lock);
+ set_bit(BDI_pending, &bdi->state);
- wb = &bdi->wb;
- wb->task = kthread_run(bdi_writeback_thread, wb, "flush-%s",
- dev_name(bdi->dev));
- /*
- * If task creation fails, then readd the bdi to
- * the pending list and force writeout of the bdi
- * from this forker thread. That will free some memory
- * and we can try again.
- */
- if (IS_ERR(wb->task)) {
- wb->task = NULL;
+ /* Make sure no one uses the picked bdi */
+ synchronize_rcu();
+ task = kthread_run(bdi_writeback_thread, &bdi->wb, "flush-%s",
+ dev_name(bdi->dev));
+ if (IS_ERR(task)) {
/*
- * Add this 'bdi' to the back, so we get
- * a chance to flush other bdi's to free
- * memory.
+ * If thread creation fails, then readd the bdi back to
+ * the list and force writeout of the bdi from this
+ * forker thread. That will free some memory and we can
+ * try again. Add it to the tail so we get a chance to
+ * flush other bdi's to free memory.
*/
spin_lock_bh(&bdi_lock);
- list_add_tail(&bdi->bdi_list, &bdi_pending_list);
+ list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
spin_unlock_bh(&bdi_lock);
bdi_flush_io(bdi);
- }
+ } else
+ bdi->wb.task = task;
}
return 0;
}
-static void bdi_add_to_pending(struct rcu_head *head)
-{
- struct backing_dev_info *bdi;
-
- bdi = container_of(head, struct backing_dev_info, rcu_head);
- INIT_LIST_HEAD(&bdi->bdi_list);
-
- spin_lock(&bdi_lock);
- list_add_tail(&bdi->bdi_list, &bdi_pending_list);
- spin_unlock(&bdi_lock);
-
- /*
- * We are now on the pending list, wake up bdi_forker_task()
- * to finish the job and add us back to the active bdi_list
- */
- wake_up_process(default_backing_dev_info.wb.task);
-}
-
-/*
- * Add the default flusher task that gets created for any bdi
- * that has dirty data pending writeout
- */
-void static bdi_add_default_flusher_task(struct backing_dev_info *bdi)
-{
- if (!bdi_cap_writeback_dirty(bdi))
- return;
-
- if (WARN_ON(!test_bit(BDI_registered, &bdi->state))) {
- printk(KERN_ERR "bdi %p/%s is not registered!\n",
- bdi, bdi->name);
- return;
- }
-
- /*
- * Check with the helper whether to proceed adding a task. Will only
- * abort if we two or more simultanous calls to
- * bdi_add_default_flusher_task() occured, further additions will block
- * waiting for previous additions to finish.
- */
- if (!test_and_set_bit(BDI_pending, &bdi->state)) {
- list_del_rcu(&bdi->bdi_list);
-
- /*
- * We must wait for the current RCU period to end before
- * moving to the pending list. So schedule that operation
- * from an RCU callback.
- */
- call_rcu(&bdi->rcu_head, bdi_add_to_pending);
- }
-}
-
/*
* Remove bdi from bdi_list, and ensure that it is no longer visible
*/
if (bdi_cap_flush_forker(bdi)) {
struct bdi_writeback *wb = &bdi->wb;
- wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s",
+ wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s",
dev_name(dev));
if (IS_ERR(wb->task)) {
wb->task = NULL;
bdi_debug_register(bdi, dev_name(dev));
set_bit(BDI_registered, &bdi->state);
+ trace_writeback_bdi_register(bdi);
exit:
return ret;
}
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
+ trace_writeback_bdi_unregister(bdi);
bdi_prune_sb(bdi);
if (!bdi_cap_flush_forker(bdi))
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
spin_lock_init(&bdi->wb_lock);
- INIT_RCU_HEAD(&bdi->rcu_head);
INIT_LIST_HEAD(&bdi->bdi_list);
INIT_LIST_HEAD(&bdi->work_list);
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