NFSD: Make nfsd4_rename() wait before returning NFS4ERR_DELAY

[ Upstream commit 68c522afd0b1936b48a03a4c8b81261e7597c62d ]

nfsd_rename() can kick off a CB_RECALL (via
vfs_rename() -> leases_conflict()) if a delegation is present.
Before returning NFS4ERR_DELAY, give the client holding that
delegation a chance to return it and then retry the nfsd_rename()
again, once.

This version of the patch handles renaming an existing file,
but does not deal with renaming onto an existing file. That
case will still always trigger an NFS4ERR_DELAY.

Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=354
Tested-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index e8329051dde014a60eed2bbf58ec4a2a0290a0a7..4c5cc142562b2fe98f11d99f6c850866a433d6d3 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1698,7 +1698,15 @@ retry:
                        .new_dir        = tdir,
                        .new_dentry     = ndentry,
                };
-               host_err = vfs_rename(&rd);
+               int retries;
+
+               for (retries = 1;;) {
+                       host_err = vfs_rename(&rd);
+                       if (host_err != -EAGAIN || !retries--)
+                               break;
+                       if (!nfsd_wait_for_delegreturn(rqstp, d_inode(odentry)))
+                               break;
+               }
                if (!host_err) {
                        host_err = commit_metadata(tfhp);
                        if (!host_err)