scsi: vmbus: Add function to report available ring buffer to write in total ring size percentage
Netvsc has a function to calculate how much ring buffer in percentage is
available to write. This function is also useful for storvsc and other
vmbus devices.
Define a similar function in vmbus to be used by other vmbus devices.
Signed-off-by: Long Li <[email protected]>
Acked-by: David S. Miller <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 192ed8f..9ac954e 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -35,6 +35,7 @@
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/interrupt.h>
+#include <linux/reciprocal_div.h>
#define MAX_PAGE_BUFFER_COUNT 32
#define MAX_MULTIPAGE_BUFFER_COUNT 32 /* 128K */
@@ -120,6 +121,7 @@ struct hv_ring_buffer {
struct hv_ring_buffer_info {
struct hv_ring_buffer *ring_buffer;
u32 ring_size; /* Include the shared header */
+ struct reciprocal_value ring_size_div10_reciprocal;
spinlock_t ring_lock;
u32 ring_datasize; /* < ring_size */
@@ -154,6 +156,16 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi)
return write;
}
+static inline u32 hv_get_avail_to_write_percent(
+ const struct hv_ring_buffer_info *rbi)
+{
+ u32 avail_write = hv_get_bytes_to_write(rbi);
+
+ return reciprocal_divide(
+ (avail_write << 3) + (avail_write << 1),
+ rbi->ring_size_div10_reciprocal);
+}
+
/*
* VMBUS version is 32 bit entity broken up into
* two 16 bit quantities: major_number. minor_number.
