[PATCH] separate bdi congestion functions from queue congestion functions

[PATCH] separate bdi congestion functions from queue congestion functions

Separate out the concept of "queue congestion" from "backing-dev congestion".
Congestion is a backing-dev concept, not a queue concept.

The blk_* congestion functions are retained, as wrappers around the core
backing-dev congestion functions.

This proper layering is needed so that NFS can cleanly use the congestion
functions, and so that CONFIG_BLOCK=n actually links.

Cc: "Thomas Maier" <[email protected]>
Cc: "Jens Axboe" <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: David Howells <[email protected]>
Cc: Peter Osterlund <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>