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| author | Ye Bin <yebin10@huawei.com> | 2020-09-16 14:38:59 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2020-10-18 17:36:12 +0300 |
| commit | 70022da804f0f3f152115688885608c39182082e (patch) | |
| tree | 8f28103fb7253d761900a7b5319e27705763b06f /fs | |
| parent | 0e6895ba00b7be45f3ab0d2107dda3ef1245f5b4 (diff) | |
| download | linux-70022da804f0f3f152115688885608c39182082e.tar.xz | |
ext4: fix dead loop in ext4_mb_new_blocks
As we test disk offline/online with running fsstress, we find fsstress
process is keeping running state.
kworker/u32:3-262 [004] ...1 140.787471: ext4_mb_discard_preallocations: dev 8,32 needed 114
....
kworker/u32:3-262 [004] ...1 140.787471: ext4_mb_discard_preallocations: dev 8,32 needed 114
ext4_mb_new_blocks
repeat:
ext4_mb_discard_preallocations_should_retry(sb, ac, &seq)
freed = ext4_mb_discard_preallocations
ext4_mb_discard_group_preallocations
this_cpu_inc(discard_pa_seq);
---> freed == 0
seq_retry = ext4_get_discard_pa_seq_sum
for_each_possible_cpu(__cpu)
__seq += per_cpu(discard_pa_seq, __cpu);
if (seq_retry != *seq) {
*seq = seq_retry;
ret = true;
}
As we see seq_retry is sum of discard_pa_seq every cpu, if
ext4_mb_discard_group_preallocations return zero discard_pa_seq in this
cpu maybe increase one, so condition "seq_retry != *seq" have always
been met.
Ritesh Harjani suggest to in ext4_mb_discard_group_preallocations function we
only increase discard_pa_seq when there is some PA to free.
Fixes: 07b5b8e1ac40 ("ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20200916113859.1556397-3-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/mballoc.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 132c118d12e1..ff47347012f4 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4189,7 +4189,6 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, INIT_LIST_HEAD(&list); repeat: ext4_lock_group(sb, group); - this_cpu_inc(discard_pa_seq); list_for_each_entry_safe(pa, tmp, &grp->bb_prealloc_list, pa_group_list) { spin_lock(&pa->pa_lock); @@ -4206,6 +4205,9 @@ repeat: /* seems this one can be freed ... */ ext4_mb_mark_pa_deleted(sb, pa); + if (!free) + this_cpu_inc(discard_pa_seq); + /* we can trust pa_free ... */ free += pa->pa_free; |