1 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index f41ca8486e02..e54e7e0033eb 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -93,7 +93,7 @@ extern void wb_writeout_inc(struct bdi_writeback *wb);
 /*
  * maximal error of a stat counter.
  */
-static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
+static inline unsigned long wb_stat_error(void)
 {
 #ifdef CONFIG_SMP
         return nr_cpu_ids * WB_STAT_BATCH;
@@ -122,6 +122,8 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
  * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
  *
  * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
+ * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
+ *                         inefficient.
  */
 #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
 #define BDI_CAP_NO_WRITEBACK    0x00000002
@@ -129,6 +131,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 #define BDI_CAP_STABLE_WRITES   0x00000008
 #define BDI_CAP_STRICTLIMIT     0x00000010
 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
+#define BDI_CAP_SYNCHRONOUS_IO  0x00000040
 
 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
         (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
@@ -174,6 +177,11 @@ static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
 long congestion_wait(int sync, long timeout);
 long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout);
 
+static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi)
+{
+        return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;
+}
+
 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
 {
         return bdi->capabilities & BDI_CAP_STABLE_WRITES;