This flag will be used in the next patch to let the block layer core know whether or not a SCSI request queue has been quiesced. A quiesced SCSI queue namely only processes RQF_PREEMPT requests.
Signed-off-by: Bart Van Assche <[email protected]> Cc: Ming Lei <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Johannes Thumshirn <[email protected]> --- block/blk-core.c | 29 +++++++++++++++++++++++++++++ include/linux/blkdev.h | 6 ++++++ 2 files changed, 35 insertions(+) diff --git a/block/blk-core.c b/block/blk-core.c index 842e67e0b7ab..b8d90fc29b35 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -346,6 +346,35 @@ void blk_sync_queue(struct request_queue *q) } EXPORT_SYMBOL(blk_sync_queue); +/** + * blk_set_preempt_only - set QUEUE_FLAG_PREEMPT_ONLY. + * + * Returns the previous value of the PREEMPT_ONLY flag - 0 if the flag was not + * set and 1 if the flag was already set. + */ +int blk_set_preempt_only(struct request_queue *q) +{ + unsigned long flags; + int res; + + spin_lock_irqsave(q->queue_lock, flags); + res = queue_flag_test_and_set(QUEUE_FLAG_PREEMPT_ONLY, q); + spin_unlock_irqrestore(q->queue_lock, flags); + + return res; +} +EXPORT_SYMBOL_GPL(blk_set_preempt_only); + +void blk_clear_preempt_only(struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q); + spin_unlock_irqrestore(q->queue_lock, flags); +} +EXPORT_SYMBOL_GPL(blk_clear_preempt_only); + /** * __blk_run_queue_uncond - run a queue whether or not it has been stopped * @q: The queue to run diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 9a85f6ad4f89..c4174f78c6eb 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -631,6 +631,7 @@ struct request_queue { #define QUEUE_FLAG_REGISTERED 26 /* queue has been registered to a disk */ #define QUEUE_FLAG_SCSI_PASSTHROUGH 27 /* queue supports SCSI commands */ #define QUEUE_FLAG_QUIESCED 28 /* queue has been quiesced */ +#define QUEUE_FLAG_PREEMPT_ONLY 29 /* only process REQ_PREEMPT requests */ #define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ (1 << QUEUE_FLAG_STACKABLE) | \ @@ -735,6 +736,11 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q) ((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \ REQ_FAILFAST_DRIVER)) #define blk_queue_quiesced(q) test_bit(QUEUE_FLAG_QUIESCED, &(q)->queue_flags) +#define blk_queue_preempt_only(q) \ + test_bit(QUEUE_FLAG_PREEMPT_ONLY, &(q)->queue_flags) + +extern int blk_set_preempt_only(struct request_queue *q); +extern void blk_clear_preempt_only(struct request_queue *q); static inline bool blk_account_rq(struct request *rq) { -- 2.14.2
