1 files changed, 31 insertions, 8 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 46cba261075f..500840e4a74e 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -308,11 +308,14 @@ end_io:
 static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
 {
 	struct request *rq = blk_mq_rq_from_pdu(cmd);
+	struct loop_device *lo = rq->q->queuedata;
 
 	if (!atomic_dec_and_test(&cmd->ref))
 		return;
 	kfree(cmd->bvec);
 	cmd->bvec = NULL;
+	if (req_op(rq) == REQ_OP_WRITE)
+		file_end_write(lo->lo_backing_file);
 	if (likely(!blk_should_fake_timeout(rq->q)))
 		blk_mq_complete_request(rq);
 }
@@ -387,9 +390,10 @@ 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) {
+		file_start_write(lo->lo_backing_file);
 		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 +509,17 @@ 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 +541,10 @@ 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 +982,11 @@ 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 +1248,6 @@ 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 +1255,11 @@ 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)