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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ilya Dryomov <idryomov@gmail.com>
Subject: [PATCH 4.4 126/160] libceph: bump CEPH_MSG_MAX_DATA_LEN
Date:   Mon, 19 Nov 2018 17:29:25 +0100
Message-Id: <20181119162642.690217403@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Dryomov <idryomov@gmail.com>

commit 94e6992bb560be8bffb47f287194adf070b57695 upstream.

If the read is large enough, we end up spinning in the messenger:

  libceph: osd0 192.168.122.1:6801 io error
  libceph: osd0 192.168.122.1:6801 io error
  libceph: osd0 192.168.122.1:6801 io error

This is a receive side limit, so only reads were affected.

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/ceph/libceph.h |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -72,7 +72,13 @@ struct ceph_options {
 
 #define CEPH_MSG_MAX_FRONT_LEN	(16*1024*1024)
 #define CEPH_MSG_MAX_MIDDLE_LEN	(16*1024*1024)
-#define CEPH_MSG_MAX_DATA_LEN	(16*1024*1024)
+
+/*
+ * Handle the largest possible rbd object in one message.
+ * There is no limit on the size of cephfs objects, but it has to obey
+ * rsize and wsize mount options anyway.
+ */
+#define CEPH_MSG_MAX_DATA_LEN	(32*1024*1024)
 
 #define CEPH_AUTH_NAME_DEFAULT   "guest"