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Message-Id: <20200921162037.300996211@linuxfoundation.org>
Date: Mon, 21 Sep 2020 18:27:13 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Chuck Lever <chuck.lever@...cle.com>,
Trond Myklebust <trond.myklebust@...merspace.com>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 021/118] NFS: Zero-stateid SETATTR should first return delegation
From: Chuck Lever <chuck.lever@...cle.com>
[ Upstream commit 644c9f40cf71969f29add32f32349e71d4995c0b ]
If a write delegation isn't available, the Linux NFS client uses
a zero-stateid when performing a SETATTR.
NFSv4.0 provides no mechanism for an NFS server to match such a
request to a particular client. It recalls all delegations for that
file, even delegations held by the client issuing the request. If
that client happens to hold a read delegation, the server will
recall it immediately, resulting in an NFS4ERR_DELAY/CB_RECALL/
DELEGRETURN sequence.
Optimize out this pipeline bubble by having the client return any
delegations it may hold on a file before it issues a
SETATTR(zero-stateid) on that file.
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@...merspace.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
fs/nfs/nfs4proc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 7f337188a2829..08b1fb0a9225a 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3272,8 +3272,10 @@ static int _nfs4_do_setattr(struct inode *inode,
/* Servers should only apply open mode checks for file size changes */
truncate = (arg->iap->ia_valid & ATTR_SIZE) ? true : false;
- if (!truncate)
+ if (!truncate) {
+ nfs4_inode_make_writeable(inode);
goto zero_stateid;
+ }
if (nfs4_copy_delegation_stateid(inode, FMODE_WRITE, &arg->stateid, &delegation_cred)) {
/* Use that stateid */
--
2.25.1
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