Commit df52699e4fcef ("NFSv4.1: Don't cache deviceids that have no
notifications") causes the Linux NFS client stop caching deviceid
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.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/nfsd/blocklayout.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index 03d647b..cdefaa3 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -181,6 +181,17 @@ nfsd4_block_proc_layoutcommit(struct inode *inode,
}
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,
--
1.9.1
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