[PATCH 1/3] blk-mq: Allow PCI vector offset for mapping queues

[Keith Busch <keith.busch@xxxxxxxxx>]

The PCI interrupt vectors intended to be associated with a queue may
not start at 0. This patch adds an offset parameter so blk-mq may find
the intended affinity mask. The default value is 0 so existing drivers
that don't care about this parameter don't need to change.

Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
---
 block/blk-mq-pci.c         | 12 ++++++++++--
 include/linux/blk-mq-pci.h |  2 ++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq-pci.c b/block/blk-mq-pci.c
index 76944e3271bf..1040a7705c13 100644
--- a/block/blk-mq-pci.c
+++ b/block/blk-mq-pci.c
@@ -21,6 +21,7 @@
  * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
  * @set:	tagset to provide the mapping for
  * @pdev:	PCI device associated with @set.
+ * @offset:	PCI irq starting vector offset
  *
  * This function assumes the PCI device @pdev has at least as many available
  * interrupt vectors as @set has queues.  It will then query the vector
@@ -28,13 +29,14 @@
  * that maps a queue to the CPUs that have irq affinity for the corresponding
  * vector.
  */
-int blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev)
+int __blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev,
+			    int offset)
 {
 	const struct cpumask *mask;
 	unsigned int queue, cpu;
 
 	for (queue = 0; queue < set->nr_hw_queues; queue++) {
-		mask = pci_irq_get_affinity(pdev, queue);
+		mask = pci_irq_get_affinity(pdev, queue + offset);
 		if (!mask)
 			goto fallback;
 
@@ -50,4 +52,10 @@ int blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev)
 		set->mq_map[cpu] = 0;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(__blk_mq_pci_map_queues);
+
+int blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev)
+{
+	return __blk_mq_pci_map_queues(set, pdev, 0);
+}
 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);
diff --git a/include/linux/blk-mq-pci.h b/include/linux/blk-mq-pci.h
index 6338551e0fb9..5a92ecdbd78e 100644
--- a/include/linux/blk-mq-pci.h
+++ b/include/linux/blk-mq-pci.h
@@ -5,6 +5,8 @@
 struct blk_mq_tag_set;
 struct pci_dev;
 
+int __blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev,
+			    int offset);
 int blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev);
 
 #endif /* _LINUX_BLK_MQ_PCI_H */
-- 
2.14.3