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authorKeith Busch <keith.busch@intel.com>2018-05-29 15:52:28 +0200
committerJens Axboe <axboe@kernel.dk>2018-05-29 08:59:21 -0600
commit12f5b93145450c750f315657ef239a314811aeeb (patch)
tree81c7c9f0dfc660a1c78a4404f6d5c3f99e44169b /block/blk-timeout.c
parentad103e79838d4b4cd4d6dd0bdfaef937e8652ae9 (diff)
blk-mq: Remove generation seqeunce
This patch simplifies the timeout handling by relying on the request reference counting to ensure the iterator is operating on an inflight and truly timed out request. Since the reference counting prevents the tag from being reallocated, the block layer no longer needs to prevent drivers from completing their requests while the timeout handler is operating on it: a driver completing a request is allowed to proceed to the next state without additional syncronization with the block layer. This also removes any need for generation sequence numbers since the request lifetime is prevented from being reallocated as a new sequence while timeout handling is operating on it. To enables this a refcount is added to struct request so that request users can be sure they're operating on the same request without it changing while they're processing it. The request's tag won't be released for reuse until both the timeout handler and the completion are done with it. Signed-off-by: Keith Busch <keith.busch@intel.com> [hch: slight cleanups, added back submission side hctx lock, use cmpxchg for completions] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-timeout.c')
-rw-r--r--block/blk-timeout.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 652d4d4d3e97..f95d6e6cbc96 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -214,7 +214,6 @@ void blk_add_timer(struct request *req)
req->timeout = q->rq_timeout;
blk_rq_set_deadline(req, jiffies + req->timeout);
- req->rq_flags &= ~RQF_MQ_TIMEOUT_EXPIRED;
/*
* Only the non-mq case needs to add the request to a protected list.