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block: fix elevator init check

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We can't initalize the elevator fields for flushes as flush share space
in struct request with the elevator data.  But currently we can't
communicate that a request is a flush through blk_get_request as we
can only pass READ or WRITE, and the low-level code looks at the
possible NULL bio to check for a flush.

Fix this by allowing to pass any block op and flags, and by checking for
the flush flags in __get_request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2017-01-25 11:17:11 +01:00 committed by Jens Axboe
parent 309bd96af9
commit e6f7f93d58
1 changed files with 4 additions and 22 deletions
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26
block/blk-core.c
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@ -1022,25 +1022,6 @@ int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
return 0;
}
/*
* Determine if elevator data should be initialized when allocating the
* request associated with @bio.
*/
static bool blk_rq_should_init_elevator(struct bio *bio)
{
if (!bio)
return true;
/*
* Flush requests do not use the elevator so skip initialization.
* This allows a request to share the flush and elevator data.
*/
if (op_is_flush(bio->bi_opf))
return false;
return true;
}
/**
* __get_request - get a free request
* @rl: request list to allocate from
@ -1119,10 +1100,13 @@ static struct request *__get_request(struct request_list *rl, unsigned int op,
* request is freed. This guarantees icq's won't be destroyed and
* makes creating new ones safe.
*
* Flush requests do not use the elevator so skip initialization.
* This allows a request to share the flush and elevator data.
*
* Also, lookup icq while holding queue_lock. If it doesn't exist,
* it will be created after releasing queue_lock.
*/
if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
if (!op_is_flush(op) && !blk_queue_bypass(q)) {
rq_flags |= RQF_ELVPRIV;
q->nr_rqs_elvpriv++;
if (et->icq_cache && ioc)
@ -1276,8 +1260,6 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
{
struct request *rq;
BUG_ON(rw != READ && rw != WRITE);
/* create ioc upfront */
create_io_context(gfp_mask, q->node);