From 1bf27e98d26d1e62166a456ef17460be085cbe0b Mon Sep 17 00:00:00 2001 From: Stefan Roesch Date: Fri, 18 Nov 2022 16:52:02 -0800 Subject: 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 Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton --- mm/page-writeback.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) (limited to 'mm/page-writeback.c') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index e74ef596dc27..20ae9adeb22f 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -13,6 +13,7 @@ */ #include +#include #include #include #include @@ -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) -- cgit