EXPORT_SYMBOL(default_unplug_io_fn);
struct backing_dev_info default_backing_dev_info = {
+ .name = "default",
.ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
.state = 0,
.capabilities = BDI_CAP_MAP_COPY,
EXPORT_SYMBOL_GPL(default_backing_dev_info);
static struct class *bdi_class;
+
+/*
+ * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as
+ * reader side protection for bdi_pending_list. bdi_list has RCU reader side
+ * locking.
+ */
DEFINE_SPINLOCK(bdi_lock);
LIST_HEAD(bdi_list);
LIST_HEAD(bdi_pending_list);
"BdiDirtyThresh: %8lu kB\n"
"DirtyThresh: %8lu kB\n"
"BackgroundThresh: %8lu kB\n"
- "WriteBack threads:%8lu\n"
+ "WritebackThreads: %8lu\n"
"b_dirty: %8lu\n"
"b_io: %8lu\n"
"b_more_io: %8lu\n"
/*
* Add us to the active bdi_list
*/
- spin_lock(&bdi_lock);
- list_add(&bdi->bdi_list, &bdi_list);
- spin_unlock(&bdi_lock);
+ spin_lock_bh(&bdi_lock);
+ list_add_rcu(&bdi->bdi_list, &bdi_list);
+ spin_unlock_bh(&bdi_lock);
bdi_task_init(bdi, wb);
if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list))
wb_do_writeback(me, 0);
- spin_lock(&bdi_lock);
+ spin_lock_bh(&bdi_lock);
/*
* Check if any existing bdi's have dirty data without
if (list_empty(&bdi_pending_list)) {
unsigned long wait;
- spin_unlock(&bdi_lock);
+ spin_unlock_bh(&bdi_lock);
wait = msecs_to_jiffies(dirty_writeback_interval * 10);
schedule_timeout(wait);
try_to_freeze();
bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
bdi_list);
list_del_init(&bdi->bdi_list);
- spin_unlock(&bdi_lock);
+ spin_unlock_bh(&bdi_lock);
wb = &bdi->wb;
wb->task = kthread_run(bdi_start_fn, wb, "flush-%s",
* a chance to flush other bdi's to free
* memory.
*/
- spin_lock(&bdi_lock);
+ spin_lock_bh(&bdi_lock);
list_add_tail(&bdi->bdi_list, &bdi_pending_list);
- spin_unlock(&bdi_lock);
+ spin_unlock_bh(&bdi_lock);
bdi_flush_io(bdi);
}
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
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
* waiting for previous additions to finish.
*/
if (!test_and_set_bit(BDI_pending, &bdi->state)) {
- list_move_tail(&bdi->bdi_list, &bdi_pending_list);
+ list_del_rcu(&bdi->bdi_list);
/*
- * 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
+ * We must wait for the current RCU period to end before
+ * moving to the pending list. So schedule that operation
+ * from an RCU callback.
*/
- wake_up_process(default_backing_dev_info.wb.task);
+ call_rcu(&bdi->rcu_head, bdi_add_to_pending);
}
}
+/*
+ * Remove bdi from bdi_list, and ensure that it is no longer visible
+ */
+static void bdi_remove_from_list(struct backing_dev_info *bdi)
+{
+ spin_lock_bh(&bdi_lock);
+ list_del_rcu(&bdi->bdi_list);
+ spin_unlock_bh(&bdi_lock);
+
+ synchronize_rcu();
+}
+
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
{
goto exit;
}
- spin_lock(&bdi_lock);
- list_add_tail(&bdi->bdi_list, &bdi_list);
- spin_unlock(&bdi_lock);
+ spin_lock_bh(&bdi_lock);
+ list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+ spin_unlock_bh(&bdi_lock);
bdi->dev = dev;
wb->task = NULL;
ret = -ENOMEM;
- spin_lock(&bdi_lock);
- list_del(&bdi->bdi_list);
- spin_unlock(&bdi_lock);
+ bdi_remove_from_list(bdi);
goto exit;
}
}
bdi_debug_register(bdi, dev_name(dev));
+ set_bit(BDI_registered, &bdi->state);
exit:
return ret;
}
/*
* Make sure nobody finds us on the bdi_list anymore
*/
- spin_lock(&bdi_lock);
- list_del(&bdi->bdi_list);
- spin_unlock(&bdi_lock);
+ bdi_remove_from_list(bdi);
/*
* Finally, kill the kernel threads. We don't need to be RCU
- * safe anymore, since the bdi is gone from visibility.
+ * 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)
+ list_for_each_entry(wb, &bdi->wb_list, list) {
+ thaw_process(wb->task);
kthread_stop(wb->task);
+ }
+}
+
+/*
+ * This bdi is going away now, make sure that no super_blocks point to it
+ */
+static void bdi_prune_sb(struct backing_dev_info *bdi)
+{
+ struct super_block *sb;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (sb->s_bdi == bdi)
+ sb->s_bdi = NULL;
+ }
+ spin_unlock(&sb_lock);
}
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
+ bdi_prune_sb(bdi);
+
if (!bdi_cap_flush_forker(bdi))
bdi_wb_shutdown(bdi);
bdi_debug_unregister(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->wb_list);
INIT_LIST_HEAD(&bdi->work_list);
{
int i;
- WARN_ON(bdi_has_dirty_io(bdi));
+ /*
+ * Splice our entries to the default_backing_dev_info, if this
+ * bdi disappears
+ */
+ if (bdi_has_dirty_io(bdi)) {
+ struct bdi_writeback *dst = &default_backing_dev_info.wb;
+
+ spin_lock(&inode_lock);
+ list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
+ list_splice(&bdi->wb.b_io, &dst->b_io);
+ list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
+ spin_unlock(&inode_lock);
+ }
bdi_unregister(bdi);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff