1 files changed, 40 insertions, 5 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 5c4ee70d5cf3..edbaac6c0573 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -624,20 +624,38 @@ static int loop_switch(struct loop_device *lo, struct file *file)
 }
 
 /*
+ * Helper to flush the IOs in loop, but keeping loop thread running
+ */
+static int loop_flush(struct loop_device *lo)
+{
+	/* loop not yet configured, no running thread, nothing to flush */
+	if (!lo->lo_thread)
+		return 0;
+
+	return loop_switch(lo, NULL);
+}
+
+/*
  * Do the actual switch; called from the BIO completion routine
  */
 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
 {
 	struct file *file = p->file;
 	struct file *old_file = lo->lo_backing_file;
-	struct address_space *mapping = file->f_mapping;
+	struct address_space *mapping;
+
+	/* if no new file, only flush of queued bios requested */
+	if (!file)
+		goto out;
 
+	mapping = file->f_mapping;
 	mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
 	lo->lo_backing_file = file;
 	lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
 		mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
 	lo->old_gfp_mask = mapping_gfp_mask(mapping);
 	mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
+out:
 	complete(&p->wait);
 }
 
@@ -901,6 +919,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
 
 	kthread_stop(lo->lo_thread);
 
+	lo->lo_queue->unplug_fn = NULL;
 	lo->lo_backing_file = NULL;
 
 	loop_release_xfer(lo);
@@ -936,8 +955,10 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 {
 	int err;
 	struct loop_func_table *xfer;
+	uid_t uid = current_uid();
 
-	if (lo->lo_encrypt_key_size && lo->lo_key_owner != current->uid &&
+	if (lo->lo_encrypt_key_size &&
+	    lo->lo_key_owner != uid &&
 	    !capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (lo->lo_state != Lo_bound)
@@ -992,7 +1013,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	if (info->lo_encrypt_key_size) {
 		memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
 		       info->lo_encrypt_key_size);
-		lo->lo_key_owner = current->uid;
+		lo->lo_key_owner = uid;
 	}	
 
 	return 0;
@@ -1343,11 +1364,25 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
 	struct loop_device *lo = disk->private_data;
 
 	mutex_lock(&lo->lo_ctl_mutex);
-	--lo->lo_refcnt;
 
-	if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) && !lo->lo_refcnt)
+	if (--lo->lo_refcnt)
+		goto out;
+
+	if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
+		/*
+		 * In autoclear mode, stop the loop thread
+		 * and remove configuration after last close.
+		 */
 		loop_clr_fd(lo, NULL);
+	} else {
+		/*
+		 * Otherwise keep thread (if running) and config,
+		 * but flush possible ongoing bios in thread.
+		 */
+		loop_flush(lo);
+	}
 
+out:
 	mutex_unlock(&lo->lo_ctl_mutex);
 
 	return 0;