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authorTejun Heo <tj@kernel.org>2019-06-13 15:30:38 -0700
committerJens Axboe <axboe@kernel.dk>2019-06-15 10:39:37 -0600
commitf539da82f2158916e154d206054e0efd5df7ab61 (patch)
tree38d5600b740b77c771b1f7893fb29bf5b7ac67cc
parent5de0073fcd50cc1f150895a7bb04d3cf8067b1d7 (diff)
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: 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> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/blk-cgroup.c8
1 files changed, 6 insertions, 2 deletions
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);
+ }
}
}