Messages in this thread | | | Date | Thu, 10 Jan 2002 16:27:18 -0500 (EST) | From | Michael Zhu <> | Subject | About block device request function. |
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Hi, I have a question of the block device request function. I use the following sentences to change the request function of a block device.
spin_lock_irq(&io_request_lock);
original_make_request_fn = blk_dev[i].request_queue.make_request_fn;
blk_dev[i].request_queue.make_request_fn = kti_make_request_fn;
spin_unlock_irq(&io_request_lock);
"i" is the major number of a block device.
You know blk_dev[] is the global block device array. When I use those sentences to change the floppy block device's request function, it works. The major number of the floppy disk is 2. But when I use the same one to change the hard disk's request function, it doesn't work. I found that the blk_dev[3].request_queue.make_request_fn is NULL. Does that mean that the make_request_fn() of the hard disk is NULL. I can't believe it. Can anyone give me an answer?
Michael
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