drbd: make suspend_io() / resume_io() must be thread and recursion safe

[cascardo/linux.git] / drivers / block / drbd / drbd_nl.c

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 6137789..c7cd3df 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -865,9 +865,11 @@ char *ppsize(char *buf, unsigned long long size)
  * and can be long lived.
  * This changes an device->flag, is triggered by drbd internals,
  * and should be short-lived. */
+/* It needs to be a counter, since multiple threads might
+   independently suspend and resume IO. */
 void drbd_suspend_io(struct drbd_device *device)
 {
-       set_bit(SUSPEND_IO, &device->flags);
+       atomic_inc(&device->suspend_cnt);
        if (drbd_suspended(device))
                return;
        wait_event(device->misc_wait, !atomic_read(&device->ap_bio_cnt));
@@ -875,8 +877,8 @@ void drbd_suspend_io(struct drbd_device *device)
 
 void drbd_resume_io(struct drbd_device *device)
 {
-       clear_bit(SUSPEND_IO, &device->flags);
-       wake_up(&device->misc_wait);
+       if (atomic_dec_and_test(&device->suspend_cnt))
+               wake_up(&device->misc_wait);
 }
 
 /**