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authorJan Kara <jack@suse.cz>2024-01-23 20:58:26 +0300
committerJens Axboe <axboe@kernel.dk>2024-02-06 19:44:03 +0300
commitf814bdda774c183b0cc15ec8f3b6e7c6f4527ba5 (patch)
treef423245937edd1e7cf7be59f948d04c8c66ee956 /block
parentf3c89983cb4fc00be64eb0d5cbcfcdf2cacb965e (diff)
downloadlinux-f814bdda774c183b0cc15ec8f3b6e7c6f4527ba5.tar.xz
blk-wbt: Fix detection of dirty-throttled tasks
The detection of dirty-throttled tasks in blk-wbt has been subtly broken since its beginning in 2016. Namely if we are doing cgroup writeback and the throttled task is not in the root cgroup, balance_dirty_pages() will set dirty_sleep for the non-root bdi_writeback structure. However blk-wbt checks dirty_sleep only in the root cgroup bdi_writeback structure. Thus detection of recently throttled tasks is not working in this case (we noticed this when we switched to cgroup v2 and suddently writeback was slow). Since blk-wbt has no easy way to get to proper bdi_writeback and furthermore its intention has always been to work on the whole device rather than on individual cgroups, just move the dirty_sleep timestamp from bdi_writeback to backing_dev_info. That fixes the checking for recently throttled task and saves memory for everybody as a bonus. CC: stable@vger.kernel.org Fixes: b57d74aff9ab ("writeback: track if we're sleeping on progress in balance_dirty_pages()") Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20240123175826.21452-1-jack@suse.cz [axboe: fixup indentation errors] Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-wbt.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 5ba3cd574eac..0c0e270a8265 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -163,9 +163,9 @@ static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
*/
static bool wb_recent_wait(struct rq_wb *rwb)
{
- struct bdi_writeback *wb = &rwb->rqos.disk->bdi->wb;
+ struct backing_dev_info *bdi = rwb->rqos.disk->bdi;
- return time_before(jiffies, wb->dirty_sleep + HZ);
+ return time_before(jiffies, bdi->last_bdp_sleep + HZ);
}
static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb,