[PATCH v2 4/8] blk-throttle: Fix IO hang for a corner case

Baolin Wang
2020-10-08T03:53:00Z

It can not scale up in throtl_adjusted_limit() if we set bps or iops is
1, which will cause IO hang when enable low limit. Thus we should treat
1 as a illegal value to avoid this issue.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
block/blk-throttle.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index b0d8f7c..0649bce 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1687,13 +1687,13 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
goto out_finish;

ret = -EINVAL;
- if (!strcmp(tok, "rbps"))
+ if (!strcmp(tok, "rbps") && val > 1)
v[0] = val;
- else if (!strcmp(tok, "wbps"))
+ else if (!strcmp(tok, "wbps") && val > 1)
v[1] = val;
- else if (!strcmp(tok, "riops"))
+ else if (!strcmp(tok, "riops") && val > 1)
v[2] = min_t(u64, val, UINT_MAX);
- else if (!strcmp(tok, "wiops"))
+ else if (!strcmp(tok, "wiops") && val > 1)
v[3] = min_t(u64, val, UINT_MAX);
else if (off == LIMIT_LOW && !strcmp(tok, "idle"))
idle_time = val;
--
1.8.3.1