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 <bart.vanassche@xxxxxxx>
Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
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
