In kernel v2.6.18 RQF_PREEMPT was only set for IDE preempt requests. Later on the SCSI core was modified such that RQF_PREEMPT requests was set for all requests submitted by __scsi_execute(), including power management requests. RQF_PREEMPT requests are the only requests processed in the SDEV_QUIESCE state. Instead of setting RQF_PREEMPT for all requests submitted by __scsi_execute(), only set RQF_PM for power management requests. Modify blk_get_request() such that it blocks in pm-only mode on non-RQF_PM requests. Leave the code out from scsi_prep_state_check() that is no longer reachable.
Signed-off-by: Bart Van Assche <[email protected]> Cc: Martin K. Petersen <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Jianchao Wang <[email protected]> Cc: Ming Lei <[email protected]> Cc: Alan Stern <[email protected]> Cc: Johannes Thumshirn <[email protected]> --- block/blk-core.c | 9 +++++---- drivers/scsi/scsi_lib.c | 28 ++++++++++++---------------- include/linux/blk-mq.h | 2 ++ include/linux/blkdev.h | 6 ++---- 4 files changed, 21 insertions(+), 24 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index b83798c03ca8..3378fe478e67 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -908,11 +908,11 @@ EXPORT_SYMBOL(blk_alloc_queue); /** * blk_queue_enter() - try to increase q->q_usage_counter * @q: request queue pointer - * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT + * @flags: BLK_MQ_REQ_NOWAIT, BLK_MQ_REQ_PREEMPT and/or BLK_MQ_REQ_PM */ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) { - const bool pm = flags & BLK_MQ_REQ_PREEMPT; + const bool pm = flags & BLK_MQ_REQ_PM; while (true) { bool success = false; @@ -1570,7 +1570,7 @@ static struct request *get_request(struct request_queue *q, unsigned int op, goto retry; } -/* flags: BLK_MQ_REQ_PREEMPT and/or BLK_MQ_REQ_NOWAIT. */ +/* flags: BLK_MQ_REQ_PREEMPT, BLK_MQ_REQ_PM and/or BLK_MQ_REQ_NOWAIT. */ static struct request *blk_old_get_request(struct request_queue *q, unsigned int op, blk_mq_req_flags_t flags) { @@ -1613,7 +1613,8 @@ struct request *blk_get_request(struct request_queue *q, unsigned int op, struct request *req; WARN_ON_ONCE(op & REQ_NOWAIT); - WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); + WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT | + BLK_MQ_REQ_PM)); if (q->mq_ops) { req = blk_mq_alloc_request(q, op, flags); diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 007bb2bc817d..481158ab5081 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -248,8 +248,8 @@ void scsi_queue_insert(struct scsi_cmnd *cmd, int reason) * @sshdr: optional decoded sense header * @timeout: request timeout in seconds * @retries: number of times to retry request - * @flags: flags for ->cmd_flags - * @rq_flags: flags for ->rq_flags + * @flags: REQ_* flags for ->cmd_flags + * @rq_flags: RQF_* flags for ->rq_flags * @resid: optional residual length * * Returns the scsi_cmnd result field if a command was executed, or a negative @@ -267,7 +267,8 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, req = blk_get_request(sdev->request_queue, data_direction == DMA_TO_DEVICE ? - REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT); + REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, + rq_flags & RQF_PM ? BLK_MQ_REQ_PM : 0); if (IS_ERR(req)) return ret; rq = scsi_req(req); @@ -1353,20 +1354,15 @@ scsi_prep_state_check(struct scsi_device *sdev, struct request *req) ret = BLKPREP_DEFER; break; case SDEV_QUIESCE: - /* - * If the devices is blocked we defer normal commands. - */ - if (req && !(req->rq_flags & RQF_PREEMPT)) - ret = BLKPREP_DEFER; + WARN_ON_ONCE(!(req->rq_flags & RQF_PM)); break; - default: - /* - * For any other not fully online state we only allow - * special commands. In particular any user initiated - * command is not allowed. - */ - if (req && !(req->rq_flags & RQF_PREEMPT)) - ret = BLKPREP_KILL; + case SDEV_CANCEL: + ret = BLKPREP_KILL; + break; + case SDEV_CREATED: + case SDEV_RUNNING: + /* This code is never reached */ + WARN_ONCE(true, "sdev state = %d\n", sdev->sdev_state); break; } } diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 1da59c16f637..f15c1de51f5e 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -223,6 +223,8 @@ enum { BLK_MQ_REQ_INTERNAL = (__force blk_mq_req_flags_t)(1 << 2), /* set RQF_PREEMPT */ BLK_MQ_REQ_PREEMPT = (__force blk_mq_req_flags_t)(1 << 3), + /* for power management requests */ + BLK_MQ_REQ_PM = (__force blk_mq_req_flags_t)(1 << 4), }; struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 1a08edbddf9f..1b3fe78872dc 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -99,8 +99,7 @@ typedef __u32 __bitwise req_flags_t; #define RQF_MQ_INFLIGHT ((__force req_flags_t)(1 << 6)) /* don't call prep for this one */ #define RQF_DONTPREP ((__force req_flags_t)(1 << 7)) -/* set for "ide_preempt" requests and also for requests for which the SCSI - "quiesce" state must be ignored. */ +/* set for "ide_preempt" requests */ #define RQF_PREEMPT ((__force req_flags_t)(1 << 8)) /* contains copies of user pages */ #define RQF_COPY_USER ((__force req_flags_t)(1 << 9)) @@ -508,8 +507,7 @@ struct request_queue { unsigned long queue_flags; /* * Number of contexts that have called blk_set_pm_only(). If this - * counter is above zero then only RQF_PM and RQF_PREEMPT requests are - * processed. + * counter is above zero then only RQF_PM requests are processed. */ atomic_t pm_only; -- 2.18.0
