| Message ID | 1485185361-29786-2-git-send-email-hch@lst.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
On 01/23/2017 04:29 PM, Christoph Hellwig wrote: > 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 > commnicate 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> > --- > block/blk-core.c | 26 ++++---------------------- > 1 file changed, 4 insertions(+), 22 deletions(-) > Reviewed-by: Hannes Reinecke <hare@suse.com> Cheers, Hannes
On Mon, Jan 23 2017, Christoph Hellwig wrote: > 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 > commnicate 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. We check for REQ_PREFLUSH | REQ_FUA in so many places though, might not be a bad idea to keep the helper but just make it take the opf and fix up the other locations too. The fact that PREFLUSH|FUA is the magic to check for is somewhat tribal knowledge.
On Tue, Jan 24, 2017 at 08:06:39AM -0700, Jens Axboe wrote: > We check for REQ_PREFLUSH | REQ_FUA in so many places though, might not > be a bad idea to keep the helper but just make it take the opf and fix > up the other locations too. The fact that PREFLUSH|FUA is the magic to > check for is somewhat tribal knowledge. I'll see if I can come up with something sensible. The current helper using the bio and the magic 0 value is not exactly helpful. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
diff --git a/block/blk-core.c b/block/blk-core.c index a61f140..732b719 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -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 (bio->bi_opf & (REQ_PREFLUSH | REQ_FUA)) - 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 & (REQ_PREFLUSH | REQ_FUA)) && !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);
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 commnicate 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> --- block/blk-core.c | 26 ++++---------------------- 1 file changed, 4 insertions(+), 22 deletions(-)