Commit b8ab956c authored by Jan Kara's avatar Jan Kara Committed by Jens Axboe

block: Expand a bit documentation about elevator_allow_merge_fn

Explain that two requests can be merged without
elevator_allow_merge_fn() being called.
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent e167dfb5
...@@ -946,7 +946,11 @@ elevator_allow_merge_fn called whenever the block layer determines ...@@ -946,7 +946,11 @@ elevator_allow_merge_fn called whenever the block layer determines
request safely. The io scheduler may still request safely. The io scheduler may still
want to stop a merge at this point if it want to stop a merge at this point if it
results in some sort of conflict internally, results in some sort of conflict internally,
this hook allows it to do that. this hook allows it to do that. Note however
that two *requests* can still be merged at later
time. Currently the io scheduler has no way to
prevent that. It can only learn about the fact
from elevator_merge_req_fn callback.
elevator_dispatch_fn* fills the dispatch queue with ready requests. elevator_dispatch_fn* fills the dispatch queue with ready requests.
I/O schedulers are free to postpone requests by I/O schedulers are free to postpone requests by
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