I intercept the request function of floppy disk device
by changing the pointer,
"blk_dev.request_queue.request_fn", in my kernel
module. The following is the source code.
In my own my_request_fn_proc() I use the "req =
to get the pointer of the request structure. When
req->cmd is WRITE I encrypt all the b_data buffer of
the buffer header. Then I call the
original_request_fn_proc(). And it works. The data on
the floppy disk is some kind of cipher data. The
trouble is when the req->cmd is READ. I don't know
whether the b_data buffer contains the data read from
the floppy disk after I call the
original_request_fn_proc() function. When read a block
from the block device, where is the data is placed?
In my module I use the blkdev_next_request() function
to get the next request. When I want to do the same
thing to this next request, the Linux kernel
deadlocked. I must reboot the OS. What is wrong?
Any idea will be appreciated. Thanks in advance.
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