do not have a corresponding kernel virtual address space mapping) and
low-memory pages.
-Note: Please refer to DMA-mapping.txt for a discussion on PCI high mem DMA
-aspects and mapping of scatter gather lists, and support for 64 bit PCI.
+Note: Please refer to Documentation/PCI/PCI-DMA-mapping.txt for a discussion
+on PCI high mem DMA aspects and mapping of scatter gather lists, and support
+for 64 bit PCI.
Special handling is required only for cases where i/o needs to happen on
pages at physical memory addresses beyond what the device can support. In these
queue and specific I/O schedulers. Unless stated otherwise, elevator is used
to refer to both parts and I/O scheduler to specific I/O schedulers.
-Block layer implements generic dispatch queue in ll_rw_blk.c and elevator.c.
+Block layer implements generic dispatch queue in block/*.c.
The generic dispatch queue is responsible for properly ordering barrier
requests, requeueing, handling non-fs requests and all other subtleties.
change to another one dynamically.
A block layer call to the i/o scheduler follows the convention elv_xxx(). This
-calls elevator_xxx_fn in the elevator switch (drivers/block/elevator.c). Oh,
-xxx and xxx might not match exactly, but use your imagination. If an elevator
+calls elevator_xxx_fn in the elevator switch (block/elevator.c). Oh, xxx
+and xxx might not match exactly, but use your imagination. If an elevator
doesn't implement a function, the switch does nothing or some minimal house
keeping work.
io_request_lock for serialization need to be modified accordingly.
Usually it's as easy as adding a global lock:
- static spinlock_t my_driver_lock = SPIN_LOCK_UNLOCKED;
+ static DEFINE_SPINLOCK(my_driver_lock);
and passing the address to that lock to blk_init_queue().