1 files changed, 60 insertions, 16 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 46cba261075f..1b6ee91f8eb9 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -313,6 +313,8 @@ static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
 		return;
 	kfree(cmd->bvec);
 	cmd->bvec = NULL;
+	if (req_op(rq) == REQ_OP_WRITE)
+		kiocb_end_write(&cmd->iocb);
 	if (likely(!blk_should_fake_timeout(rq->q)))
 		blk_mq_complete_request(rq);
 }
@@ -387,9 +389,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
 		cmd->iocb.ki_flags = 0;
 	}
 
-	if (rw == ITER_SOURCE)
+	if (rw == ITER_SOURCE) {
+		kiocb_start_write(&cmd->iocb);
 		ret = file->f_op->write_iter(&cmd->iocb, &iter);
-	else
+	} else
 		ret = file->f_op->read_iter(&cmd->iocb, &iter);
 
 	lo_rw_aio_do_completion(cmd);
@@ -505,6 +508,17 @@ static void loop_assign_backing_file(struct loop_device *lo, struct file *file)
 	lo->lo_min_dio_size = loop_query_min_dio_size(lo);
 }
 
+static int loop_check_backing_file(struct file *file)
+{
+	if (!file->f_op->read_iter)
+		return -EINVAL;
+
+	if ((file->f_mode & FMODE_WRITE) && !file->f_op->write_iter)
+		return -EINVAL;
+
+	return 0;
+}
+
 /*
  * loop_change_fd switched the backing store of a loopback device to
  * a new file. This is useful for operating system installers to free up
@@ -526,6 +540,10 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
 	if (!file)
 		return -EBADF;
 
+	error = loop_check_backing_file(file);
+	if (error)
+		return error;
+
 	/* suppress uevents while reconfiguring the device */
 	dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
 
@@ -963,6 +981,11 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
 
 	if (!file)
 		return -EBADF;
+
+	error = loop_check_backing_file(file);
+	if (error)
+		return error;
+
 	is_loop = is_loop_device(file);
 
 	/* This is safe, since we have a reference from open(). */
@@ -1224,12 +1247,6 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	lo->lo_flags &= ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
 	lo->lo_flags |= (info->lo_flags & LOOP_SET_STATUS_SETTABLE_FLAGS);
 
-	if (size_changed) {
-		loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
-					   lo->lo_backing_file);
-		loop_set_size(lo, new_size);
-	}
-
 	/* update the direct I/O flag if lo_offset changed */
 	loop_update_dio(lo);
 
@@ -1237,6 +1254,11 @@ out_unfreeze:
 	blk_mq_unfreeze_queue(lo->lo_queue, memflags);
 	if (partscan)
 		clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
+	if (!err && size_changed) {
+		loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
+					   lo->lo_backing_file);
+		loop_set_size(lo, new_size);
+	}
 out_unlock:
 	mutex_unlock(&lo->lo_mutex);
 	if (partscan)
@@ -1409,17 +1431,34 @@ static int loop_set_dio(struct loop_device *lo, unsigned long arg)
 	return 0;
 }
 
-static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
+static int loop_set_block_size(struct loop_device *lo, blk_mode_t mode,
+			       struct block_device *bdev, unsigned long arg)
 {
 	struct queue_limits lim;
 	unsigned int memflags;
 	int err = 0;
 
-	if (lo->lo_state != Lo_bound)
-		return -ENXIO;
+	/*
+	 * If we don't hold exclusive handle for the device, upgrade to it
+	 * here to avoid changing device under exclusive owner.
+	 */
+	if (!(mode & BLK_OPEN_EXCL)) {
+		err = bd_prepare_to_claim(bdev, loop_set_block_size, NULL);
+		if (err)
+			return err;
+	}
+
+	err = mutex_lock_killable(&lo->lo_mutex);
+	if (err)
+		goto abort_claim;
+
+	if (lo->lo_state != Lo_bound) {
+		err = -ENXIO;
+		goto unlock;
+	}
 
 	if (lo->lo_queue->limits.logical_block_size == arg)
-		return 0;
+		goto unlock;
 
 	sync_blockdev(lo->lo_device);
 	invalidate_bdev(lo->lo_device);
@@ -1432,6 +1471,11 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
 	loop_update_dio(lo);
 	blk_mq_unfreeze_queue(lo->lo_queue, memflags);
 
+unlock:
+	mutex_unlock(&lo->lo_mutex);
+abort_claim:
+	if (!(mode & BLK_OPEN_EXCL))
+		bd_abort_claiming(bdev, loop_set_block_size);
 	return err;
 }
 
@@ -1450,9 +1494,6 @@ static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
 	case LOOP_SET_DIRECT_IO:
 		err = loop_set_dio(lo, arg);
 		break;
-	case LOOP_SET_BLOCK_SIZE:
-		err = loop_set_block_size(lo, arg);
-		break;
 	default:
 		err = -EINVAL;
 	}
@@ -1507,9 +1548,12 @@ static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
 		break;
 	case LOOP_GET_STATUS64:
 		return loop_get_status64(lo, argp);
+	case LOOP_SET_BLOCK_SIZE:
+		if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		return loop_set_block_size(lo, mode, bdev, arg);
 	case LOOP_SET_CAPACITY:
 	case LOOP_SET_DIRECT_IO:
-	case LOOP_SET_BLOCK_SIZE:
 		if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN))
 			return -EPERM;
 		fallthrough;