NFSD: Make nfsd4_setattr() wait before returning NFS4ERR_DELAY

nfsd_setattr() can kick off a CB_RECALL (via
notify_change() -> break_lease()) 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_setattr() again, once.

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>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 7c17b4a..d4db595 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -413,6 +413,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
        int             host_err;
        bool            get_write_count;
        bool            size_change = (iap->ia_valid & ATTR_SIZE);
+       int             retries;
 
        if (iap->ia_valid & ATTR_SIZE) {
                accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
@@ -467,7 +468,13 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
        }
 
        inode_lock(inode);
-       host_err = __nfsd_setattr(dentry, iap);
+       for (retries = 1;;) {
+               host_err = __nfsd_setattr(dentry, iap);
+               if (host_err != -EAGAIN || !retries--)
+                       break;
+               if (!nfsd_wait_for_delegreturn(rqstp, inode))
+                       break;
+       }
        if (attr->na_seclabel && attr->na_seclabel->len)
                attr->na_labelerr = security_inode_setsecctx(dentry,
                        attr->na_seclabel->data, attr->na_seclabel->len);