Commit f539da82 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

blkcg: update blkcg_print_stat() to handle larger outputs

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: default avatarTejun Heo <tj@kernel.org>
Fixes: 903d23f0 ("blk-cgroup: allow controllers to output their own stats")
Cc: stable@vger.kernel.org # v4.19+
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 5de0073f
...@@ -1006,8 +1006,12 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) ...@@ -1006,8 +1006,12 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
} }
next: next:
if (has_stats) { if (has_stats) {
off += scnprintf(buf+off, size-off, "\n"); if (off < size - 1) {
seq_commit(sf, off); off += scnprintf(buf+off, size-off, "\n");
seq_commit(sf, off);
} else {
seq_commit(sf, -1);
}
} }
} }
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment