The patch titled
Subject: mm: add bdi_set_max_bytes() function.
has been added to the -mm mm-unstable branch. Its filename is
mm-add-bdi_set_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_set_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_set_max_bytes() function.
Date: Fri, 18 Nov 2022 16:52:02 -0800
This introduces the bdi_set_max_bytes() function. The max_bytes function
does not store the max_bytes value. Instead it converts the max_bytes
value into the corresponding ratio value.
Link: https://lkml.kernel.org/r/20221119005215.3052436-8-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 | 37 ++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
--- a/include/linux/backing-dev.h~mm-add-bdi_set_max_bytes-function
+++ a/include/linux/backing-dev.h
@@ -108,6 +108,7 @@ static inline unsigned long wb_stat_erro
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_max_bytes(struct backing_dev_info *bdi, u64 max_bytes);
int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit);
/*
--- a/mm/page-writeback.c~mm-add-bdi_set_max_bytes-function
+++ a/mm/page-writeback.c
@@ -13,6 +13,7 @@
*/
#include <linux/kernel.h>
+#include <linux/math64.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/fs.h>
@@ -650,6 +651,28 @@ void wb_domain_exit(struct wb_domain *do
*/
static unsigned int bdi_min_ratio;
+static int bdi_check_pages_limit(unsigned long pages)
+{
+ unsigned long max_dirty_pages = global_dirtyable_memory();
+
+ if (pages > max_dirty_pages)
+ return -EINVAL;
+
+ return 0;
+}
+
+static unsigned long bdi_ratio_from_pages(unsigned long pages)
+{
+ unsigned long background_thresh;
+ unsigned long dirty_thresh;
+ unsigned long ratio;
+
+ global_dirty_limits(&background_thresh, &dirty_thresh);
+ ratio = div64_u64(pages * 100ULL * BDI_RATIO_SCALE, dirty_thresh);
+
+ return ratio;
+}
+
static u64 bdi_get_bytes(unsigned int ratio)
{
unsigned long background_thresh;
@@ -722,6 +745,20 @@ u64 bdi_get_max_bytes(struct backing_dev
return bdi_get_bytes(bdi->max_ratio);
}
+int bdi_set_max_bytes(struct backing_dev_info *bdi, u64 max_bytes)
+{
+ int ret;
+ unsigned long pages = max_bytes >> PAGE_SHIFT;
+ unsigned long max_ratio;
+
+ ret = bdi_check_pages_limit(pages);
+ if (ret)
+ return ret;
+
+ max_ratio = bdi_ratio_from_pages(pages);
+ return __bdi_set_max_ratio(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
