In ext4_mb_discard_group_preallocations(), if free is always less than needed,
and some PAs are always used in every loop, it will be endless loop.
Here we pick a random value to limit the max number of loop.
Change v1 -> v2:
- fix typo error, s/ramdon/random/
Signed-off-by: Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx>
Acked-by: Andreas Dilger <adilger.kernel@xxxxxxxxx>
---
fs/ext4/mballoc.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 34b610e..553fbde 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3836,6 +3836,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
int err;
int busy = 0;
int free = 0;
+ int tried = 0;
mb_debug(1, "discard preallocation for group %u\n", group);
@@ -3886,9 +3887,11 @@ repeat:
list_add(&pa->u.pa_tmp_list, &list);
}
- /* if we still need more blocks and some PAs were used, try again */
- if (free < needed && busy) {
+ /* if we still need more blocks and some PAs were used, try again,
+ here 20 is a random value. */
+ if (free < needed && busy && tried < 20) {
busy = 0;
+ tried++;
ext4_unlock_group(sb, group);
cond_resched();
goto repeat;
--
1.9.1
.
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