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nfsd/blocklayout: pretend we can send deviceid notifications 

Commit df52699e4f ("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.

Cc: stable@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Christoph Hellwig 2015-04-27 14:50:13 +02:00 committed by J. Bruce Fields
parent 5ebe6afaf0
commit 40cdc7a530
1 changed files with 11 additions and 0 deletions
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11
fs/nfsd/blocklayout.c
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@ -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,