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block, scsi: Change the preempt-only flag into a counter

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The RQF_PREEMPT flag is used for three purposes:
- In the SCSI core, for making sure that power management requests
  are executed even if a device is in the "quiesced" state.
- For domain validation by SCSI drivers that use the parallel port.
- In the IDE driver, for IDE preempt requests.
Rename "preempt-only" into "pm-only" because the primary purpose of
this mode is power management. Since the power management core may
but does not have to resume a runtime suspended device before
performing system-wide suspend and since a later patch will set
"pm-only" mode as long as a block device is runtime suspended, make
it possible to set "pm-only" mode from more than one context. Since
with this change scsi_device_quiesce() is no longer idempotent, make
that function return early if it is called for a quiesced queue.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bart Van Assche
2018-09-26 14:01:04 -07:00
committed by Jens Axboe
parent bca6b067b0
commit cd84a62e00
4 changed files with 43 additions and 27 deletions
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14
include/linux/blkdev.h
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@@ -504,6 +504,12 @@ struct request_queue {
* various queue flags, see QUEUE_* below
*/
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.
*/
atomic_t pm_only;
/*
* ida allocated id for this queue. Used to index queues from
@@ -698,7 +704,6 @@ 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_SAME_COMP) | \
@@ -736,12 +741,11 @@ bool blk_queue_flag_test_and_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)
#define blk_queue_pm_only(q) atomic_read(&(q)->pm_only)
#define blk_queue_fua(q) test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags)
extern int blk_set_preempt_only(struct request_queue *q);
extern void blk_clear_preempt_only(struct request_queue *q);
extern void blk_set_pm_only(struct request_queue *q);
extern void blk_clear_pm_only(struct request_queue *q);
static inline int queue_in_flight(struct request_queue *q)
{