diff options
Diffstat (limited to 'block/blk-mq.c')
| -rw-r--r-- | block/blk-mq.c | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 576e7112f807..e931a0e8e73d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -672,7 +672,20 @@ static void blk_mq_timeout_work(struct work_struct *work) }; int i; - if (blk_queue_enter(q, true)) + /* A deadlock might occur if a request is stuck requiring a + * timeout at the same time a queue freeze is waiting + * completion, since the timeout code would not be able to + * acquire the queue reference here. + * + * That's why we don't use blk_queue_enter here; instead, we use + * percpu_ref_tryget directly, because we need to be able to + * obtain a reference even in the short window between the queue + * starting to freeze, by dropping the first reference in + * blk_mq_freeze_queue_start, and the moment the last request is + * consumed, marked by the instant q_usage_counter reaches + * zero. + */ + if (!percpu_ref_tryget(&q->q_usage_counter)) return; blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data); @@ -1221,7 +1234,7 @@ static struct request *blk_mq_map_request(struct request_queue *q, ctx = blk_mq_get_ctx(q); hctx = q->mq_ops->map_queue(q, ctx->cpu); - if (rw_is_sync(bio_op(bio), bio->bi_rw)) + if (rw_is_sync(bio_op(bio), bio->bi_opf)) op_flags |= REQ_SYNC; trace_block_getrq(q, bio, op); @@ -1289,8 +1302,8 @@ static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie) */ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) { - const int is_sync = rw_is_sync(bio_op(bio), bio->bi_rw); - const int is_flush_fua = bio->bi_rw & (REQ_PREFLUSH | REQ_FUA); + const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf); + const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA); struct blk_map_ctx data; struct request *rq; unsigned int request_count = 0; @@ -1383,8 +1396,8 @@ done: */ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio) { - const int is_sync = rw_is_sync(bio_op(bio), bio->bi_rw); - const int is_flush_fua = bio->bi_rw & (REQ_PREFLUSH | REQ_FUA); + const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf); + const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA); struct blk_plug *plug; unsigned int request_count = 0; struct blk_map_ctx data; |