centos man page for blk_lld_busy

BLK_LLD_BUSY(9) 						   Block Devices						   BLK_LLD_BUSY(9)

NAME
       blk_lld_busy - Check if underlying low-level drivers of a device are busy

SYNOPSIS
       int blk_lld_busy(struct request_queue * q);

ARGUMENTS
       q
	   the queue of the device being checked

DESCRIPTION
       Check if underlying low-level drivers of a device are busy. If the drivers want to export their busy state, they must set own exporting
       function using blk_queue_lld_busy first.

       Basically, this function is used only by request stacking drivers to stop dispatching requests to underlying devices when underlying
       devices are busy. This behavior helps more I/O merging on the queue of the request stacking driver and prevents I/O throughput regression
       on burst I/O load.

RETURN
       0 - Not busy (The request stacking driver should dispatch request) 1 - Busy (The request stacking driver should stop dispatching request)

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							   BLK_LLD_BUSY(9)