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Caleb Sander Mateos
763ff02ce2
Currently, UBLK_IO_REGISTER_IO_BUF and UBLK_IO_UNREGISTER_IO_BUF are only permitted on the ublk_io's daemon task. But this restriction is unnecessary. ublk_register_io_buf() calls __ublk_check_and_get_req() to look up the request from the tagset and atomically take a reference on the request without accessing the ublk_io. ublk_unregister_io_buf() doesn't use the q_id or tag at all. So allow these opcodes even on tasks other than io->task. Handle UBLK_IO_UNREGISTER_IO_BUF before obtaining the ubq and io since the buffer index being unregistered is not necessarily related to the specified q_id and tag. Add a feature flag UBLK_F_BUF_REG_OFF_DAEMON that userspace can use to determine whether the kernel supports off-daemon buffer registration. Suggested-by: Ming Lei <[email protected]> Signed-off-by: Caleb Sander Mateos <[email protected]> Reviewed-by: Ming Lei <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jens Axboe <[email protected]>