The patch titled
Subject: mm: add bdi_get_max_bytes() function
has been added to the -mm mm-unstable branch. Its filename is
mm-add-bdi_get_max_bytes-function.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-bdi_get_max_bytes-function.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Stefan Roesch <shr@xxxxxxxxxxxx>
Subject: mm: add bdi_get_max_bytes() function
Date: Fri, 18 Nov 2022 16:52:00 -0800
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@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Cc: Chris Mason <clm@xxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/backing-dev.h | 1 +
mm/page-writeback.c | 17 +++++++++++++++++
2 files changed, 18 insertions(+)
--- a/include/linux/backing-dev.h~mm-add-bdi_get_max_bytes-function
+++ a/include/linux/backing-dev.h
@@ -105,6 +105,7 @@ static inline unsigned long wb_stat_erro
/* 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);
--- a/mm/page-writeback.c~mm-add-bdi_get_max_bytes-function
+++ a/mm/page-writeback.c
@@ -650,6 +650,18 @@ void wb_domain_exit(struct wb_domain *do
*/
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
}
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)
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
mm-add-bdi_set_strict_limit-function.patch
mm-add-knob-sys-class-bdi-bdi-strict_limit.patch
mm-document-sys-class-bdi-bdi-strict_limit-knob.patch
mm-use-part-per-1000000-for-bdi-ratios.patch
mm-add-bdi_get_max_bytes-function.patch
mm-split-off-__bdi_set_max_ratio-function.patch
mm-add-bdi_set_max_bytes-function.patch
mm-add-knob-sys-class-bdi-bdi-max_bytes.patch
mm-document-sys-class-bdi-bdi-max_bytes-knob.patch
mm-add-bdi_get_min_bytes-function.patch
mm-split-off-__bdi_set_min_ratio-function.patch
mm-add-bdi_set_min_bytes-function.patch
mm-add-sys-class-bdi-bdi-min_bytes-knob.patch
mm-document-sys-class-bdi-bdi-min_bytes-knob.patch
mm-add-bdi_set_max_ratio_no_scale-function.patch
mm-add-sys-class-bdi-bdi-max_ratio_fine-knob.patch
mm-document-sys-class-bdi-bdi-max_ratio_fine-knob.patch
mm-add-bdi_set_min_ratio_no_scale-function.patch
mm-add-sys-class-bdi-bdi-min_ratio_fine-knob.patch
mm-document-sys-class-bdi-bdi-min_ratio_fine-knob.patch
