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authorStefan Roesch <shr@devkernel.io>2022-11-18 16:52:00 -0800
committerAndrew Morton <akpm@linux-foundation.org>2022-11-30 15:59:04 -0800
commit00df7d51263b46ed93f7572e2d09579746f7b1eb (patch)
treef79ffb1660825cef999d7c22e3ef2ca76ec9824f
parentae82291e9ca47c3d6da6b77a00f427754aca413e (diff)
mm: add bdi_get_max_bytes() function
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. Link: https://lkml.kernel.org/r/20221119005215.3052436-6-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--include/linux/backing-dev.h1
-rw-r--r--mm/page-writeback.c17
2 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 1b50c028e5ad..473686c32775 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -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);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index dd98b2654302..719404e0d03d 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -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)