blk-throttle: Fix IO hang for a corner case

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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index b0d8f7c..0649bce 100644 (file)
--- 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;