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| author | Tejun Heo | 2019-06-14 00:30:38 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2019-07-26 09:14:30 +0200 |
| commit | dd87cc633ba578f322c61655d90abfd8c86c74fc (patch) | |
| tree | 46dab13f72bda3f4bf1f2b97cf0ad85e317cba5c /block | |
| parent | blk-iolatency: clear use_delay when io.latency is set to zero (diff) | |
| download | kernel-qcow2-linux-dd87cc633ba578f322c61655d90abfd8c86c74fc.tar.gz kernel-qcow2-linux-dd87cc633ba578f322c61655d90abfd8c86c74fc.tar.xz kernel-qcow2-linux-dd87cc633ba578f322c61655d90abfd8c86c74fc.zip | |
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.c | 8 |
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); + } } } |