Commit 644c9f40 authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust

NFS: Zero-stateid SETATTR should first return delegation

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: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 3d7a9520
......@@ -3293,8 +3293,10 @@ 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 */
......
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