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| author | Jens Axboe <axboe@kernel.dk> | 2013-10-29 22:11:47 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2013-10-29 22:11:47 +0400 |
| commit | e7e245000110a7794de8f925b9edc06a9c852f80 (patch) | |
| tree | c774b4b9e7d7cdb59f3b4a237fd12c4e5eb8bc60 /block/blk-merge.c | |
| parent | 92f399c72af2d8cbb9d4f60e11d0d67ca738147f (diff) | |
| download | linux-e7e245000110a7794de8f925b9edc06a9c852f80.tar.xz | |
blk-mq: don't disallow request merges for req->special being set
For blk-mq, if a driver has requested per-request payload data
to carry command structures, they are stuffed into req->special.
For an old style request based driver, req->special is used
for the same purpose but indicates that a per-driver request
structure has been prepared for the request already. So for the
old style driver, we do not merge such requests.
As most/all blk-mq drivers will use the payload feature, and
since we have no problem merging on these, make this check
dependent on whether it's a blk-mq enabled driver or not.
Reported-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-merge.c')
| -rw-r--r-- | block/blk-merge.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 5f2448253797..1ffc58977835 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -308,6 +308,17 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req, return ll_new_hw_segment(q, req, bio); } +/* + * blk-mq uses req->special to carry normal driver per-request payload, it + * does not indicate a prepared command that we cannot merge with. + */ +static bool req_no_special_merge(struct request *req) +{ + struct request_queue *q = req->q; + + return !q->mq_ops && req->special; +} + static int ll_merge_requests_fn(struct request_queue *q, struct request *req, struct request *next) { @@ -319,7 +330,7 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req, * First check if the either of the requests are re-queued * requests. Can't merge them if they are. */ - if (req->special || next->special) + if (req_no_special_merge(req) || req_no_special_merge(next)) return 0; /* @@ -416,7 +427,7 @@ static int attempt_merge(struct request_queue *q, struct request *req, if (rq_data_dir(req) != rq_data_dir(next) || req->rq_disk != next->rq_disk - || next->special) + || req_no_special_merge(next)) return 0; if (req->cmd_flags & REQ_WRITE_SAME && @@ -515,7 +526,7 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) return false; /* must be same device and not a special request */ - if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) + if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) return false; /* only merge integrity protected bio into ditto rq */ |