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| author | Jens Axboe <jens.axboe@oracle.com> | 2009-10-04 20:36:19 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-10-04 20:36:19 +0200 |
| commit | e00c54c36ac2024c3a8a37432e2e2698ff849594 (patch) | |
| tree | 0b392ba588939a7ee0c405ada8b22047fad9daff | |
| parent | ac481c20ef8f6c6f2be75d581863f40c43874ef7 (diff) | |
| download | linux-e00c54c36ac2024c3a8a37432e2e2698ff849594.tar.bz2 | |
cfq-iosched: don't delay async queue if it hasn't dispatched at all
We cannot delay for the first dispatch of the async queue if it
hasn't dispatched at all, since that could present a local user
DoS attack vector using an app that just did slow timed sync reads
while filling memory.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
| -rw-r--r-- | block/cfq-iosched.c | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index ebab60c6be9d..9c4b679908f4 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1345,16 +1345,9 @@ static int cfq_dispatch_requests(struct request_queue *q, int force) unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; unsigned int depth; - /* - * must wait a bit longer - */ - if (last_sync < cfqd->cfq_slice[1]) { - cfq_schedule_dispatch(cfqd, - cfqd->cfq_slice[1] - last_sync); - return 0; - } - depth = last_sync / cfqd->cfq_slice[1]; + if (!depth && !cfqq->dispatched) + depth = 1; if (depth < max_dispatch) max_dispatch = depth; } |