| Message ID | 20190613223041.606735-3-tj@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] blk-iolatency: clear use_delay when io.latency is set to zero | expand |
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 1f7127b03490..e4715b35d42c 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1006,8 +1006,12 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) } next: if (has_stats) { - off += scnprintf(buf+off, size-off, "\n"); - seq_commit(sf, off); + if (off < size - 1) { + off += scnprintf(buf+off, size-off, "\n"); + seq_commit(sf, off); + } else { + seq_commit(sf, -1); + } } }
Depending on the number of devices, blkcg stats can go over the default seqfile buf size. seqfile normally retries with a larger buffer but since the ->pd_stat() addition, blkcg_print_stat() doesn't tell seqfile that overflow has happened and the output gets printed truncated. Fix it by calling seq_commit() w/ -1 on possible overflows. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 903d23f0a354 ("blk-cgroup: allow controllers to output their own stats") Cc: stable@vger.kernel.org # v4.19+ Cc: Josef Bacik <jbacik@fb.com> --- block/blk-cgroup.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)