In Linux, when you make a blocking i/o call like read or accept, what actually happens?

My thoughts: the process get taken out of the run queue, put into a waiting or blocking state on some wait queue. Then when a tcp connection is made (for accept) or the hard drive is ready or something for a file read, a hardware interrupt is raised which lets those processes waiting to wake up and run (in the case of a file read, how does linux know what processes to awaken, as there could be lots of processes waiting on different files?). Or perhaps instead of hardware interrupts, the individual process itself polls to check availability. Not sure, help?