From 23c47d2ada9f96731492a67b28c0072715075baa Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 15 Nov 2017 17:33:00 -0800 Subject: bdi: introduce BDI_CAP_SYNCHRONOUS_IO As discussed at https://lkml.kernel.org/r/<20170728165604.10455-1-ross.zwisler@linux.intel.com> someday we will remove rw_page(). If so, we need something to detect such super-fast storage on which synchronous IO operations like the current rw_page are always a win. Introduces BDI_CAP_SYNCHRONOUS_IO to indicate such devices. With it, we could use various optimization techniques. Link: http://lkml.kernel.org/r/1505886205-9671-3-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim Cc: Christoph Hellwig Cc: Dan Williams Cc: Ross Zwisler Cc: Hugh Dickins Cc: Ilya Dryomov Cc: Jens Axboe Cc: Sergey Senozhatsky Cc: Huang Ying Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/backing-dev.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/backing-dev.h') diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index f41ca8486e02..7360e79e9a2f 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -122,6 +122,8 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold. * * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback. + * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be + * inefficient. */ #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 #define BDI_CAP_NO_WRITEBACK 0x00000002 @@ -129,6 +131,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); #define BDI_CAP_STABLE_WRITES 0x00000008 #define BDI_CAP_STRICTLIMIT 0x00000010 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020 +#define BDI_CAP_SYNCHRONOUS_IO 0x00000040 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) @@ -174,6 +177,11 @@ static inline int wb_congested(struct bdi_writeback *wb, int cong_bits) long congestion_wait(int sync, long timeout); long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout); +static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi) +{ + return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO; +} + static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi) { return bdi->capabilities & BDI_CAP_STABLE_WRITES; -- cgit v1.2.3 From 2bce774e8245e95db81872ec39522cde8b486fc8 Mon Sep 17 00:00:00 2001 From: Wang Long Date: Wed, 15 Nov 2017 17:39:03 -0800 Subject: writeback: remove unused function parameter The parameter `struct bdi_writeback *wb` is not been used in the function body. Remove it. Link: http://lkml.kernel.org/r/1509685485-15278-1-git-send-email-wanglong19@meituan.com Signed-off-by: Wang Long Reviewed-by: Jan Kara Acked-by: Tejun Heo Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/backing-dev.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/backing-dev.h') diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 7360e79e9a2f..e54e7e0033eb 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -93,7 +93,7 @@ extern void wb_writeout_inc(struct bdi_writeback *wb); /* * maximal error of a stat counter. */ -static inline unsigned long wb_stat_error(struct bdi_writeback *wb) +static inline unsigned long wb_stat_error(void) { #ifdef CONFIG_SMP return nr_cpu_ids * WB_STAT_BATCH; -- cgit v1.2.3