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 <bart.vanassche@xxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
block/blk-core.c | 30 ++++++++++++++++++++++++++++++
block/blk-mq-debugfs.c | 1 +
include/linux/blkdev.h | 6 ++++++
3 files changed, 37 insertions(+)
diff --git a/block/blk-core.c b/block/blk-core.c
index 842e67e0b7ab..ed992cbd107f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -346,6 +346,36 @@ void blk_sync_queue(struct request_queue *q)
}
EXPORT_SYMBOL(blk_sync_queue);
+/**
+ * blk_set_preempt_only - set QUEUE_FLAG_PREEMPT_ONLY
+ * @q: request queue pointer
+ *
+ * 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/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 7f4a1ba532af..75f31535f280 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -74,6 +74,7 @@ static const char *const blk_queue_flag_name[] = {
QUEUE_FLAG_NAME(REGISTERED),
QUEUE_FLAG_NAME(SCSI_PASSTHROUGH),
QUEUE_FLAG_NAME(QUIESCED),
+ QUEUE_FLAG_NAME(PREEMPT_ONLY),
};
#undef QUEUE_FLAG_NAME
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3f7b08a9b9ae..89555eea742b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -630,6 +630,7 @@ 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_SAME_COMP) | \
@@ -730,6 +731,11 @@ 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
