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-rw-r--r--mm/backing-dev.c82
1 files changed, 18 insertions, 64 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 72e6eb96efe2..dbc66815a0fe 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -50,8 +50,6 @@ static struct timer_list sync_supers_timer;
static int bdi_sync_supers(void *);
static void sync_supers_timer_fn(unsigned long);
-static void bdi_add_default_flusher_thread(struct backing_dev_info *bdi);
-
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/seq_file.h>
@@ -331,6 +329,7 @@ static int bdi_forker_thread(void *ptr)
set_user_nice(current, 0);
for (;;) {
+ bool fork = false;
struct task_struct *task;
struct backing_dev_info *bdi, *tmp;
@@ -349,23 +348,30 @@ static int bdi_forker_thread(void *ptr)
* 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_thread(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);
/* 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);
@@ -378,13 +384,13 @@ static int bdi_forker_thread(void *ptr)
__set_current_state(TASK_RUNNING);
/*
- * This is our real job - check for pending entries in
- * bdi_pending_list, and create the threads 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);
+
+ /* Make sure no one uses the picked bdi */
+ synchronize_rcu();
task = kthread_run(bdi_writeback_thread, &bdi->wb, "flush-%s",
dev_name(bdi->dev));
@@ -397,7 +403,7 @@ static int bdi_forker_thread(void *ptr)
* 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);
@@ -408,57 +414,6 @@ static int bdi_forker_thread(void *ptr)
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 thread that gets created for any bdi
- * that has dirty data pending writeout
- */
-static void bdi_add_default_flusher_thread(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 thread. Will only
- * abort if we two or more simultanous calls to
- * bdi_add_default_flusher_thread() 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
*/
@@ -599,7 +554,6 @@ int bdi_init(struct backing_dev_info *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);