1 files changed, 37 insertions, 30 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index b865a3fa52f3..d8bec3c1bb1f 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1132,6 +1132,7 @@ out_bdi_put:
 
 /**
  * cgroup_writeback_umount - flush inode wb switches for umount
+ * @sb: target super_block
  *
  * This function is called when a super_block is about to be destroyed and
  * flushes in-flight inode wb switches.  An inode wb switch goes through
@@ -1140,8 +1141,12 @@ out_bdi_put:
  * rare occurrences and synchronize_rcu() can take a while, perform
  * flushing iff wb switches are in flight.
  */
-void cgroup_writeback_umount(void)
+void cgroup_writeback_umount(struct super_block *sb)
 {
+
+	if (!(sb->s_bdi->capabilities & BDI_CAP_WRITEBACK))
+		return;
+
 	/*
 	 * SB_ACTIVE should be reliably cleared before checking
 	 * isw_nr_in_flight, see generic_shutdown_super().
@@ -1381,12 +1386,13 @@ static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
 
 static void inode_sync_complete(struct inode *inode)
 {
+	assert_spin_locked(&inode->i_lock);
+
 	inode->i_state &= ~I_SYNC;
 	/* If inode is clean an unused, put it into LRU now... */
 	inode_add_lru(inode);
-	/* Waiters must see I_SYNC cleared before being woken up */
-	smp_mb();
-	wake_up_bit(&inode->i_state, __I_SYNC);
+	/* Called with inode->i_lock which ensures memory ordering. */
+	inode_wake_up_bit(inode, __I_SYNC);
 }
 
 static bool inode_dirtied_after(struct inode *inode, unsigned long t)
@@ -1505,30 +1511,27 @@ static int write_inode(struct inode *inode, struct writeback_control *wbc)
  * Wait for writeback on an inode to complete. Called with i_lock held.
  * Caller must make sure inode cannot go away when we drop i_lock.
  */
-static void __inode_wait_for_writeback(struct inode *inode)
-	__releases(inode->i_lock)
-	__acquires(inode->i_lock)
+void inode_wait_for_writeback(struct inode *inode)
 {
-	DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
-	wait_queue_head_t *wqh;
+	struct wait_bit_queue_entry wqe;
+	struct wait_queue_head *wq_head;
+
+	assert_spin_locked(&inode->i_lock);
 
-	wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
-	while (inode->i_state & I_SYNC) {
+	if (!(inode->i_state & I_SYNC))
+		return;
+
+	wq_head = inode_bit_waitqueue(&wqe, inode, __I_SYNC);
+	for (;;) {
+		prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
+		/* Checking I_SYNC with inode->i_lock guarantees memory ordering. */
+		if (!(inode->i_state & I_SYNC))
+			break;
 		spin_unlock(&inode->i_lock);
-		__wait_on_bit(wqh, &wq, bit_wait,
-			      TASK_UNINTERRUPTIBLE);
+		schedule();
 		spin_lock(&inode->i_lock);
 	}
-}
-
-/*
- * Wait for writeback on an inode to complete. Caller must have inode pinned.
- */
-void inode_wait_for_writeback(struct inode *inode)
-{
-	spin_lock(&inode->i_lock);
-	__inode_wait_for_writeback(inode);
-	spin_unlock(&inode->i_lock);
+	finish_wait(wq_head, &wqe.wq_entry);
 }
 
 /*
@@ -1539,16 +1542,20 @@ void inode_wait_for_writeback(struct inode *inode)
 static void inode_sleep_on_writeback(struct inode *inode)
 	__releases(inode->i_lock)
 {
-	DEFINE_WAIT(wait);
-	wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
-	int sleep;
+	struct wait_bit_queue_entry wqe;
+	struct wait_queue_head *wq_head;
+	bool sleep;
+
+	assert_spin_locked(&inode->i_lock);
 
-	prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
-	sleep = inode->i_state & I_SYNC;
+	wq_head = inode_bit_waitqueue(&wqe, inode, __I_SYNC);
+	prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
+	/* Checking I_SYNC with inode->i_lock guarantees memory ordering. */
+	sleep = !!(inode->i_state & I_SYNC);
 	spin_unlock(&inode->i_lock);
 	if (sleep)
 		schedule();
-	finish_wait(wqh, &wait);
+	finish_wait(wq_head, &wqe.wq_entry);
 }
 
 /*
@@ -1752,7 +1759,7 @@ static int writeback_single_inode(struct inode *inode,
 		 */
 		if (wbc->sync_mode != WB_SYNC_ALL)
 			goto out;
-		__inode_wait_for_writeback(inode);
+		inode_wait_for_writeback(inode);
 	}
 	WARN_ON(inode->i_state & I_SYNC);
 	/*