Patch "nfsd/blocklayout: pretend we can send deviceid notifications" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

nfsd/blocklayout: pretend we can send deviceid notifications

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nfsd-blocklayout-pretend-we-can-send-deviceid-notifications.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Christoph Hellwig <[email protected]>
Date: Mon, 27 Apr 2015 14:50:13 +0200
Subject: nfsd/blocklayout: pretend we can send deviceid notifications

From: Christoph Hellwig <[email protected]>

commit 40cdc7a530c7a075557651a071354bb42b99df08 upstream.

Commit df52699e4fcef ("NFSv4.1: Don't cache deviceids that have no notifications") causes the Linux NFS client to stop caching deviceid's unless a server pretends to support deviceid notifications. While this behavior is stupid and the language around this area in rfc5661 is a mess carified by an errata that I submittted, Trond insists on this behavior. Not caching deviceids degrades block layout performance massively as a GETDEVICEINFO is fairly expensive.

So add this hack to make the Linux client happy again.

---
 fs/nfsd/blocklayout.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

@@ -181,6 +181,17 @@ nfsd4_block_proc_layoutcommit(struct ino
 }
 
 const struct nfsd4_layout_ops bl_layout_ops = {
+	/*
+	 * Pretend that we send notification to the client.  This is a blatant
+	 * lie to force recent Linux clients to cache our device IDs.
+	 * We rarely ever change the device ID, so the harm of leaking deviceids
+	 * for a while isn't too bad.  Unfortunately RFC5661 is a complete mess
+	 * in this regard, but I filed errata 4119 for this a while ago, and
+	 * hopefully the Linux client will eventually start caching deviceids
+	 * without this again.
+	 */
+	.notify_types		=
+			NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
 	.proc_getdeviceinfo	= nfsd4_block_proc_getdeviceinfo,
 	.encode_getdeviceinfo	= nfsd4_block_encode_getdeviceinfo,
 	.proc_layoutget		= nfsd4_block_proc_layoutget,

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/nfsd-fix-the-check-for-confirmed-openowner-in-nfs4_preprocess_stateid_op.patch queue-4.0/nfsd-blocklayout-pretend-we-can-send-deviceid-notifications.patch