From 20578bdfd0418efb11ec316229e670d085cd574a Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Tue, 20 Nov 2018 10:52:38 +0900 Subject: block: Initialize BIO I/O priority early For the synchronous I/O path case (read(), write() etc system calls), a BIO I/O priority is not initialized until the execution of blk_init_request_from_bio() when the BIO is submitted and a request initialized for the BIO execution. This is due to the ki_ioprio field of the struct kiocb defined on stack being always initialized to IOPRIO_CLASS_NONE, regardless of the calling process I/O context ioprio value set with ioprio_set(). This late initialization can result in the BIO being merged to pending requests even when the I/O priorities differ. Fix this by initializing the ki_iopriority field of on stack struct kiocb using the get_current_ioprio() helper, ensuring that all BIOs allocated and submitted for the system call execution see the correct intended I/O priority early. With this, since a BIO I/O priority is always set to the intended effective value for both the sync and async path, blk_init_request_from_bio() can be simplified. Reviewed-by: Christoph Hellwig Reviewed-by: Adam Manzanares Signed-off-by: Damien Le Moal Signed-off-by: Jens Axboe --- block/blk-core.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'block/blk-core.c') diff --git a/block/blk-core.c b/block/blk-core.c index dde30b08aa14..04f5be473638 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -814,10 +814,7 @@ void blk_init_request_from_bio(struct request *req, struct bio *bio) req->cmd_flags |= REQ_FAILFAST_MASK; req->__sector = bio->bi_iter.bi_sector; - if (ioprio_valid(bio_prio(bio))) - req->ioprio = bio_prio(bio); - else - req->ioprio = get_current_ioprio(); + req->ioprio = bio_prio(bio); req->write_hint = bio->bi_write_hint; blk_rq_bio_prep(req->q, req, bio); } -- cgit v1.2.3