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mm: add bdi_set_max_bytes() function 

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@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>
This commit is contained in:
Stefan Roesch 2022-11-18 16:52:02 -08:00 committed by Andrew Morton
parent efc3e6ad53
commit 1bf27e98d2
2 changed files with 38 additions and 0 deletions
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1
include/linux/backing-dev.h
View File

@ -108,6 +108,7 @@ static inline unsigned long wb_stat_error(void)
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);
/*

37
mm/page-writeback.c
View File

@ -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 *dom)
*/
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_info *bdi)
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)