Il 16/11/2012 07:15, Stefan Hajnoczi ha scritto: >> > >> > So why not just make a string 'filename' property and open it directly >> > in virtio-blk-data-plane? Then it's at least clear to the user and >> > management tools what the device is capable of doing. > There are some benefits to raw_get_aio_fd(): > > 1. virtio-blk-data-plane is only a subset virtio-blk implementation, > it still needs a regular virtio-blk-pci device (with BDS) in order to > run. If we use a filename the user would have to specify it twice. > > 2. Fetching the file descriptor in this way ensures that the image > file is format=raw. > > 3. virtio-blk-data-plane uses Linux AIO and raw-posix.c has checks > which I don't want to duplicate - we can simply check s->use_aio in > raw_get_aio_fd() to confirm that Linux AIO can be used.
Agreed. This is not vhost-blk, for which I agree that opening the file would make more sense (so you have no BDS at all). It's just a stopgap measure for something that should become the standard implementation. Paolo
