[PATCH 4.0 114/148] nfsd/blocklayout: pretend we can send deviceid notifications

Greg Kroah-Hartman
2015-06-03T12:25:37Z

From: Christoph Hellwig <hch@lst.de>

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.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -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,