[PATCH 3.12 117/142] libceph: gracefully handle large reply messages from the mon

[Jiri Slaby]

From: Sage Weil <sage@xxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 73c3d4812b4c755efeca0140f606f83772a39ce4 upstream.

We preallocate a few of the message types we get back from the mon.  If we
get a larger message than we are expecting, fall back to trying to allocate
a new one instead of blindly using the one we have.

Signed-off-by: Sage Weil <sage@xxxxxxxxxx>
Reviewed-by: Ilya Dryomov <ilya.dryomov@xxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 net/ceph/mon_client.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index 2ac9ef35110b..dbcbf5a4707f 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -1041,7 +1041,15 @@ static struct ceph_msg *mon_alloc_msg(struct ceph_connection *con,
 	if (!m) {
 		pr_info("alloc_msg unknown type %d\n", type);
 		*skip = 1;
+	} else if (front_len > m->front_alloc_len) {
+		pr_warning("mon_alloc_msg front %d > prealloc %d (%u#%llu)\n",
+			   front_len, m->front_alloc_len,
+			   (unsigned int)con->peer_name.type,
+			   le64_to_cpu(con->peer_name.num));
+		ceph_msg_put(m);
+		m = ceph_msg_new(type, front_len, GFP_NOFS, false);
 	}
+
 	return m;
 }
 
-- 
2.1.0

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