@@ -105,6 +105,7 @@ static inline unsigned long wb_stat_error(void)
/* BDI ratio is expressed as part per 1000000 for finer granularity. */
#define BDI_RATIO_SCALE 10000
+u64 bdi_get_max_bytes(struct backing_dev_info *bdi);
int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit);
@@ -650,6 +650,18 @@ void wb_domain_exit(struct wb_domain *dom)
*/
static unsigned int bdi_min_ratio;
+static u64 bdi_get_bytes(unsigned int ratio)
+{
+ unsigned long background_thresh;
+ unsigned long dirty_thresh;
+ u64 bytes;
+
+ global_dirty_limits(&background_thresh, &dirty_thresh);
+ bytes = (dirty_thresh * PAGE_SIZE * ratio) / BDI_RATIO_SCALE / 100;
+
+ return bytes;
+}
+
int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
{
unsigned int delta;
@@ -701,6 +713,11 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
}
EXPORT_SYMBOL(bdi_set_max_ratio);
+u64 bdi_get_max_bytes(struct backing_dev_info *bdi)
+{
+ return bdi_get_bytes(bdi->max_ratio);
+}
+
int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit)
{
if (strict_limit > 1)
This adds a function to return the specified value for max_bytes. It converts the stored max_ratio of the bdi to the corresponding bytes value. It introduces the bdi_get_bytes helper function to do the conversion. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The helper function will also be used by the min_bytes bdi knob. Signed-off-by: Stefan Roesch <shr@devkernel.io> --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+)