tree 3b7df2807aebe7cec855965c2a077898651e81cf
parent c6ca97b30c47c7ad36107d3764bb4dc37026d171
author Jens Axboe <axboe@kernel.dk> 1577572794 -0700
committer Jens Axboe <axboe@kernel.dk> 1579565042 -0700

io_uring: add support for IORING_SETUP_CLAMP

Some applications like to start small in terms of ring size, and then
ramp up as needed. This is a bit tricky to do currently, since we don't
advertise the max ring size.

This adds IORING_SETUP_CLAMP. If set, and the values for SQ or CQ ring
size exceed what we support, then clamp them at the max values instead
of returning -EINVAL. Since we return the chosen ring sizes after setup,
no further changes are needed on the application side. io_uring already
changes the ring sizes if the application doesn't ask for power-of-two
sizes, for example.

Signed-off-by: Jens Axboe <axboe@kernel.dk>