diff options
Diffstat (limited to 'block/blk-core.c')
| -rw-r--r-- | block/blk-core.c | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index fccb25021121..98ddef430093 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -410,6 +410,42 @@ void blk_drain_queue(struct request_queue *q, bool drain_all) } /** + * blk_queue_bypass_start - enter queue bypass mode + * @q: queue of interest + * + * In bypass mode, only the dispatch FIFO queue of @q is used. This + * function makes @q enter bypass mode and drains all requests which were + * issued before. On return, it's guaranteed that no request has ELVPRIV + * set. + */ +void blk_queue_bypass_start(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + q->bypass_depth++; + queue_flag_set(QUEUE_FLAG_BYPASS, q); + spin_unlock_irq(q->queue_lock); + + blk_drain_queue(q, false); +} +EXPORT_SYMBOL_GPL(blk_queue_bypass_start); + +/** + * blk_queue_bypass_end - leave queue bypass mode + * @q: queue of interest + * + * Leave bypass mode and restore the normal queueing behavior. + */ +void blk_queue_bypass_end(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + if (!--q->bypass_depth) + queue_flag_clear(QUEUE_FLAG_BYPASS, q); + WARN_ON_ONCE(q->bypass_depth < 0); + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL_GPL(blk_queue_bypass_end); + +/** * blk_cleanup_queue - shutdown a request queue * @q: request queue to shutdown * @@ -862,8 +898,7 @@ retry: * 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) && - !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags)) { + if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) { rw_flags |= REQ_ELVPRIV; rl->elvpriv++; if (et->icq_cache && ioc) |