When free bio

[yuanfangcc]

In this funtion,bio is not free.
`static int
vdev_disk_io_flush(struct block_device *bdev, zio_t *zio)
{
struct request_queue *q;
struct bio *bio;

q = bdev_get_queue(bdev);
if (!q)
	return (SET_ERROR(ENXIO));

bio = vdev_bio_alloc(bdev, GFP_NOIO, 0);
if (unlikely(bio == NULL))
	return (SET_ERROR(ENOMEM));

bio->bi_end_io = vdev_disk_io_flush_completion;
bio->bi_private = zio;
bio_set_flush(bio);
vdev_submit_bio(bio);
invalidate_bdev(bdev); 

if (bio != NULL)
	printk(KERN_INFO "=========vdev_disk_io_flush====bio is NOT free==\n");

return (0);

}`

This is printed.I don't understand, when is bio released.

[robn]

All you're testing is that the pointer isn't NULL, which says nothing about what, if anything, its pointing to.

As it is, the bio is handed to the kernel (vdev_submit_bio_impl -> submit_bio), which then takes ownership of it.

When the IO operation is complete, the kernel calls vdev_disk_io_flush_completion with the completed bio. This usually the bio that was passed in, but not necessarily - the kernel may modify it, split it or whatever it wants. Regardless, bio_put(bio) returns the bio to the kernel when we're done with it, and it will free it or reuse it as it likes.

[yuanfangcc]

Got it. Thank you.