1 files changed, 24 insertions, 15 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9fb0b15..f55aad4 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -44,24 +44,28 @@ inline struct block_device *I_BDEV(struct inode *inode)
 {
 	return &BDEV_I(inode)->bdev;
 }
-
 EXPORT_SYMBOL(I_BDEV);
 
 /*
- * move the inode from it's current bdi to the a new bdi. if the inode is dirty
- * we need to move it onto the dirty list of @dst so that the inode is always
- * on the right list.
+ * Move the inode from its current bdi to a new bdi. If the inode is dirty we
+ * need to move it onto the dirty list of @dst so that the inode is always on
+ * the right list.
  */
 static void bdev_inode_switch_bdi(struct inode *inode,
 			struct backing_dev_info *dst)
 {
-	spin_lock(&inode_wb_list_lock);
+	struct backing_dev_info *old = inode->i_data.backing_dev_info;
+
+	if (unlikely(dst == old))		/* deadlock avoidance */
+		return;
+	bdi_lock_two(&old->wb, &dst->wb);
 	spin_lock(&inode->i_lock);
 	inode->i_data.backing_dev_info = dst;
 	if (inode->i_state & I_DIRTY)
 		list_move(&inode->i_wb_list, &dst->wb.b_dirty);
 	spin_unlock(&inode->i_lock);
-	spin_unlock(&inode_wb_list_lock);
+	spin_unlock(&old->wb.list_lock);
+	spin_unlock(&dst->wb.list_lock);
 }
 
 static sector_t max_block(struct block_device *bdev)
@@ -1448,6 +1452,8 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
 
 int blkdev_put(struct block_device *bdev, fmode_t mode)
 {
+	mutex_lock(&bdev->bd_mutex);
+
 	if (mode & FMODE_EXCL) {
 		bool bdev_free;
 
@@ -1456,7 +1462,6 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
 		 * are protected with bdev_lock.  bd_mutex is to
 		 * synchronize disk_holder unlinking.
 		 */
-		mutex_lock(&bdev->bd_mutex);
 		spin_lock(&bdev_lock);
 
 		WARN_ON_ONCE(--bdev->bd_holders < 0);
@@ -1474,17 +1479,21 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
 		 * If this was the last claim, remove holder link and
 		 * unblock evpoll if it was a write holder.
 		 */
-		if (bdev_free) {
-			if (bdev->bd_write_holder) {
-				disk_unblock_events(bdev->bd_disk);
-				disk_check_events(bdev->bd_disk);
-				bdev->bd_write_holder = false;
-			}
+		if (bdev_free && bdev->bd_write_holder) {
+			disk_unblock_events(bdev->bd_disk);
+			bdev->bd_write_holder = false;
 		}
-
-		mutex_unlock(&bdev->bd_mutex);
 	}
 
+	/*
+	 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
+	 * event.  This is to ensure detection of media removal commanded
+	 * from userland - e.g. eject(1).
+	 */
+	disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
+
+	mutex_unlock(&bdev->bd_mutex);
+
 	return __blkdev_put(bdev, mode, 0);
 }
 EXPORT_SYMBOL(blkdev_put);