is a helper function typically called from character device
routines to start I/O on a user process buffer.
The maximum amount of data to transfer with each call
is determined by
call converts the I/O request into a
request and passes the new request to the driver's
routine for processing.
normally describes user space addresses,
needs to lock those pages into memory.
This is done by calling
for the appropriate pages.
always awaits the completion of the entire requested transfer before
returning, unless an error condition is detected earlier.
A break-down of the arguments follows:
The device number identifying the device to interact with.
The description of the entire transfer as requested by the user process.
Currently, the results of passing a
structure with the
set to anything other than
The ioflag argument from the