[PATCH 6.1 073/127] libceph: fix potential hang in ceph_osdc_notify()

Greg Kroah-Hartman
2023-08-09T10:56:00Z

From: Ilya Dryomov <idryomov@gmail.com>

commit e6e2843230799230fc5deb8279728a7218b0d63c upstream.

If the cluster becomes unavailable, ceph_osdc_notify() may hang even
with osd_request_timeout option set because linger_notify_finish_wait()
waits for MWatchNotify NOTIFY_COMPLETE message with no associated OSD
request in flight -- it's completely asynchronous.

Introduce an additional timeout, derived from the specified notify
timeout. While at it, switch both waits to killable which is more
correct.

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ceph/osd_client.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)

--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -3334,17 +3334,24 @@ static int linger_reg_commit_wait(struct
int ret;

dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
- ret = wait_for_completion_interruptible(&lreq->reg_commit_wait);
+ ret = wait_for_completion_killable(&lreq->reg_commit_wait);
return ret ?: lreq->reg_commit_error;
}

-static int linger_notify_finish_wait(struct ceph_osd_linger_request *lreq)
+static int linger_notify_finish_wait(struct ceph_osd_linger_request *lreq,
+ unsigned long timeout)
{
- int ret;
+ long left;

dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
- ret = wait_for_completion_interruptible(&lreq->notify_finish_wait);
- return ret ?: lreq->notify_finish_error;
+ left = wait_for_completion_killable_timeout(&lreq->notify_finish_wait,
+ ceph_timeout_jiffies(timeout));
+ if (left <= 0)
+ left = left ?: -ETIMEDOUT;
+ else
+ left = lreq->notify_finish_error; /* completed */
+
+ return left;
}

/*
@@ -4896,7 +4903,8 @@ int ceph_osdc_notify(struct ceph_osd_cli
linger_submit(lreq);
ret = linger_reg_commit_wait(lreq);
if (!ret)
- ret = linger_notify_finish_wait(lreq);
+ ret = linger_notify_finish_wait(lreq,
+ msecs_to_jiffies(2 * timeout * MSEC_PER_SEC));
else
dout("lreq %p failed to initiate notify %d\n", lreq, ret);