[PATCH AUTOSEL 5.1 080/141] f2fs: fix is_idle() check for discard type

Sasha Levin
2019-07-19T04:05:27Z

From: Sahitya Tummala <stummala@codeaurora.org>

[ Upstream commit 56659ce838456c6f2315ce8a4bd686ac4b23e9d1 ]

The discard thread should issue upto dpolicy->max_requests at once
and wait for all those discard requests at once it reaches
dpolicy->max_requests. It should then sleep for dpolicy->min_interval
timeout before issuing the next batch of discard requests. But in the
current code of is_idle(), it checks for dcc_info->queued_discard and
aborts issuing the discard batch of max_requests. This
dcc_info->queued_discard will be true always once one discard command
is issued.

It is thus resulting into this type of discard request pattern -

- Issue discard request#1
- is_idle() returns false, discard thread waits for request#1 and then
sleeps for min_interval 50ms.
- Issue discard request#2
- is_idle() returns false, discard thread waits for request#2 and then
sleeps for min_interval 50ms.
- and so on for all other discard requests, assuming f2fs is idle w.r.t
other conditions.

With this fix, the pattern will look like this -

- Issue discard request#1
- Issue discard request#2
and so on upto max_requests of 8
- Issue discard request#8
- wait for min_interval 50ms.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/f2fs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index f1157d5c62bb..1024550ad11a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2194,7 +2194,7 @@ static inline bool is_idle(struct f2fs_sb_info *sbi, int type)
get_pages(sbi, F2FS_DIO_WRITE))
return false;

- if (SM_I(sbi) && SM_I(sbi)->dcc_info &&
+ if (type != DISCARD_TIME && SM_I(sbi) && SM_I(sbi)->dcc_info &&
atomic_read(&SM_I(sbi)->dcc_info->queued_discard))
return false;

--
2.20.1