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authorJens Axboe <jens.axboe@oracle.com>2006-12-20 11:06:15 +0100
committerJens Axboe <jens.axboe@oracle.com>2006-12-20 11:06:15 +0100
commit126ec9a676f601818dc3a85af0552b146410d888 (patch)
tree5cf2bae7274acf4037159b55930fd91a78967b09
parentda775265021b61d5eb81df155e36cb0810f6df53 (diff)
[PATCH] block: document io scheduler allow_merge_fn hook
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r--Documentation/block/biodoc.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index c6c9a9c10d7..3adaace328a 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -946,6 +946,13 @@ elevator_merged_fn called when a request in the scheduler has been
scheduler for example, to reposition the request
if its sorting order has changed.
+elevator_allow_merge_fn called whenever the block layer determines
+ that a bio can be merged into an existing
+ request safely. The io scheduler may still
+ want to stop a merge at this point if it
+ results in some sort of conflict internally,
+ this hook allows it to do that.
+
elevator_dispatch_fn fills the dispatch queue with ready requests.
I/O schedulers are free to postpone requests by
not filling the dispatch queue unless @force