From: Tejun Heo <tj@kernel.org>
To: axboe@kernel.dk, jbacik@fb.com
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
kernel-team@fb.com, dennis@kernel.org, jack@suse.cz,
Tejun Heo <tj@kernel.org>,
stable@vger.kernel.org
Subject: [PATCH 2/5] blkcg: update blkcg_print_stat() to handle larger outputs
Date: Thu, 13 Jun 2019 15:30:38 -0700 [thread overview]
Message-ID: <20190613223041.606735-3-tj@kernel.org> (raw)
In-Reply-To: <20190613223041.606735-1-tj@kernel.org>
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(-)
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);
+ }
}
}
--
2.17.1
next prev parent reply other threads:[~2019-06-13 22:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-13 22:30 [PATCHSET block/for-linus] Assorted blkcg fixes Tejun Heo
2019-06-13 22:30 ` [PATCH 1/5] blk-iolatency: clear use_delay when io.latency is set to zero Tejun Heo
2019-06-13 22:30 ` Tejun Heo [this message]
2019-06-13 22:30 ` [PATCH 3/5] blkcg: perpcu_ref init/exit should be done from blkg_alloc/free() Tejun Heo
2019-06-13 22:30 ` [PATCH 4/5] blkcg: blkcg_activate_policy() should initialize ancestors first Tejun Heo
2019-06-13 22:30 ` [PATCH 5/5] blkcg, writeback: dead memcgs shouldn't contribute to writeback ownership arbitration Tejun Heo
2019-06-19 11:20 ` Jan Kara
2019-06-15 7:40 ` [PATCHSET block/for-linus] Assorted blkcg fixes Jens Axboe
2019-06-15 15:50 ` Tejun Heo
2019-06-15 16:40 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190613223041.606735-3-tj@kernel.org \
--to=tj@kernel.org \
--cc=axboe@kernel.dk \
--cc=dennis@kernel.org \
--cc=jack@suse.cz \
--cc=jbacik@fb.com \
--cc=kernel-team@fb.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).