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authorTejun Heo <tj@kernel.org>2019-06-14 01:30:38 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-07-26 10:14:30 +0300
commitdd87cc633ba578f322c61655d90abfd8c86c74fc (patch)
tree46dab13f72bda3f4bf1f2b97cf0ad85e317cba5c /block
parent73efdc5d7d3b27d158eb46b161606bd492e3bcec (diff)
downloadlinux-dd87cc633ba578f322c61655d90abfd8c86c74fc.tar.xz
blkcg: update blkcg_print_stat() to handle larger outputs
commit f539da82f2158916e154d206054e0efd5df7ab61 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
-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 c630e02836a8..527524134693 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1016,8 +1016,12 @@ 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);
+ }
}
}