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-rw-r--r--include/linux/backing-dev.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index f41ca8486e02..7360e79e9a2f 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -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;

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