Il 01/07/2014 17:21, Kevin Wolf ha scritto:
Does this bs->file forwarding work for more than the raw driver? For
example, if drv is an image format driver that needs to read some
metadata from the image before it can submit the payload, does this
still do what you were intending?
Sorry for not understanding the problem, and you are right, these
patches can't support other formats, and for solving the dependency,
changes to image format driver should be needed.
Then let's drop the bs->file recursion here and add an explicit
.bdrv_io_plug/unplug callback to the raw driver.
Actually I thought about this in my review, and there's no reason for
this not to work for image formats.
While bs->file is plugged, image formats will start executing their
bdrv_co_readv/bdrv_co_writev callbacks, and issue reads or writes as
necessary. The reads and writes will accumulate in bs->file until it is
unplugged, which is exactly the effect we want.
The change in bdrv_drain_all is ugly though. I don't have a better
idea, but I would like to understand better why it is needed. Ming Lei,
did you see a deadlock without it?
Paolo
