[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" <balagi@justmail.de>
Cc: "Jens Axboe" <jens.axboe@oracle.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 20 insertions, 4 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9575e3a5ff2a..7bfcde2d5578 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -651,8 +651,26 @@ extern void blk_recount_segments(request_queue_t *, struct bio *);
 extern int scsi_cmd_ioctl(struct file *, struct gendisk *, unsigned int, void __user *);
 extern int sg_scsi_ioctl(struct file *, struct request_queue *,
                 struct gendisk *, struct scsi_ioctl_command __user *);
-extern void blk_clear_queue_congested(request_queue_t *q, int rw);
-extern void blk_set_queue_congested(request_queue_t *q, int rw);
+
+/*
+ * A queue has just exitted congestion.  Note this in the global counter of
+ * congested queues, and wake up anyone who was waiting for requests to be
+ * put back.
+ */
+static inline void blk_clear_queue_congested(request_queue_t *q, int rw)
+{
+        clear_bdi_congested(&q->backing_dev_info, rw);
+}
+
+/*
+ * A queue has just entered congestion.  Flag that in the queue's VM-visible
+ * state flags and increment the global gounter of congested queues.
+ */
+static inline void blk_set_queue_congested(request_queue_t *q, int rw)
+{
+        set_bdi_congested(&q->backing_dev_info, rw);
+}
+
 extern void blk_start_queue(request_queue_t *q);
 extern void blk_stop_queue(request_queue_t *q);
 extern void blk_sync_queue(struct request_queue *q);
@@ -767,10 +785,8 @@ extern int blk_queue_init_tags(request_queue_t *, int, struct blk_queue_tag *);
 extern void blk_queue_free_tags(request_queue_t *);
 extern int blk_queue_resize_tags(request_queue_t *, int);
 extern void blk_queue_invalidate_tags(request_queue_t *);
-extern long blk_congestion_wait(int rw, long timeout);
 extern struct blk_queue_tag *blk_init_tags(int);
 extern void blk_free_tags(struct blk_queue_tag *);
-extern void blk_congestion_end(int rw);
 
 static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
                                                 int tag)