Remove lib/ublksrv_aio.c about ublksrv HOT 3 OPEN

Hi Ming,

There is no user of lib/ublksrv_aio.c now except demo_event.c. What about removing it from lib/ so that the library is simpler? I think related code can be moved into demo_event.c.

libnbd uses it:

https://github.com/libguestfs/libnbd/tree/master/ublk

Also the following project uses it too:

https://gitlab.com/amarjargal.gundjalam/qemu/-/blob/ublk_test1/block/export/ublk.c

BTW, lib/ublksrv_aio.c uses pthread_spin_lock(), eventfd()... which should not be included in a library.

Can you explain a bit why libublksrv can't use pthread_spin_lock(), eventfd()? The former is from libpthread, and the latter is one syscall.
I think it is pretty fine to include it.

But if you needn't it, I think it is fine to add config option to not
build ublksrv_aio.c into libublksrv.

thanks,
Ming

from ublksrv.

Such as, it can be done in the following way:

./configure --disable-io-offload

from ublksrv.

That's a good idea. Thanks Ming.

from ublksrv.