NFSD: Don't give out read delegations on creates

When an exclusive create is done with the mode bits
set (aka open(testfile, O_CREAT | O_EXCL, 0777)) this
causes a OPEN op followed by a SETATTR op. When a
read delegation is given in the OPEN, it causes
the SETATTR to delay with EAGAIN until the
delegation is recalled.

This patch caused exclusive creates to give out
a write delegation (which turn into no delegation)
which allows the SETATTR seamlessly succeed.

Signed-off-by: Steve Dickson <steved@redhat.com>
[bfields: do this for any CREATE, not just exclusive; comment]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c4f63399832c..44dcea96bfcb 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3113,8 +3113,17 @@ nfs4_open_delegation(struct net *net, struct svc_fh *fh,
                                 goto out;
                         if (!cb_up || !(oo->oo_flags & NFS4_OO_CONFIRMED))
                                 goto out;
+                        /*
+                         * Also, if the file was opened for write or
+                         * create, there's a good chance the client's
+                         * about to write to it, resulting in an
+                         * immediate recall (since we don't support
+                         * write delegations):
+                         */
                         if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE)
                                 flag = NFS4_OPEN_DELEGATE_WRITE;
+                        else if (open->op_create == NFS4_OPEN_CREATE)
+                                flag = NFS4_OPEN_DELEGATE_WRITE;
                         else
                                 flag = NFS4_OPEN_DELEGATE_READ;
                         break;