nfsd: untangle code in nfsd4_deleg_getattr_conflict()

The code in nfsd4_deleg_getattr_conflict() is convoluted and buggy.

With this patch we:
 - properly handle non-nfsd leases.  We must not assume flc_owner is a
    delegation unless fl_lmops == &nfsd_lease_mng_ops
 - move the main code out of the for loop
 - have a single exit which calls nfs4_put_stid()
   (and other exits which don't need to call that)

[ jlayton: refactored on top of Neil's other patch: nfsd: fix
	   nfsd4_deleg_getattr_conflict in presence of third party lease ]

Fixes: c5967721 ("NFSD: handle GETATTR conflict with write delegation")
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4state.c

@@ -8834,6 +8834,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
 	__be32 status;
 	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	struct file_lock_context *ctx;
+	struct nfs4_delegation *dp = NULL;
 	struct file_lease *fl;
 	struct iattr attrs;
 	struct nfs4_cb_fattr *ncf;
@@ -8843,84 +8844,76 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
 	ctx = locks_inode_context(inode);
 	if (!ctx)
 		return 0;
+
+#define NON_NFSD_LEASE ((void *)1)
+
 	spin_lock(&ctx->flc_lock);
 	for_each_file_lock(fl, &ctx->flc_lease) {
-		unsigned char type = fl->c.flc_type;
-
 		if (fl->c.flc_flags == FL_LAYOUT)
 			continue;
-		if (fl->fl_lmops != &nfsd_lease_mng_ops) {
-			/*
-			 * non-nfs lease, if it's a lease with F_RDLCK then
-			 * we are done; there isn't any write delegation
-			 * on this inode
-			 */
-			if (type == F_RDLCK)
-				break;
-
-			nfsd_stats_wdeleg_getattr_inc(nn);
-			spin_unlock(&ctx->flc_lock);
-
-			status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
+		if (fl->c.flc_type == F_WRLCK) {
+			if (fl->fl_lmops == &nfsd_lease_mng_ops)
+				dp = fl->c.flc_owner;
+			else
+				dp = NON_NFSD_LEASE;
+		}
+		break;
+	}
+	if (dp == NULL || dp == NON_NFSD_LEASE ||
+	    dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
+		spin_unlock(&ctx->flc_lock);
+		if (dp == NON_NFSD_LEASE) {
+			status = nfserrno(nfsd_open_break_lease(inode,
+								NFSD_MAY_READ));
 			if (status != nfserr_jukebox ||
 			    !nfsd_wait_for_delegreturn(rqstp, inode))
 				return status;
-			return 0;
 		}
-		if (type == F_WRLCK) {
-			struct nfs4_delegation *dp = fl->c.flc_owner;
+		return 0;
+	}
 
-			if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
-				spin_unlock(&ctx->flc_lock);
-				return 0;
-			}
-			nfsd_stats_wdeleg_getattr_inc(nn);
-			dp = fl->c.flc_owner;
-			refcount_inc(&dp->dl_stid.sc_count);
-			ncf = &dp->dl_cb_fattr;
-			nfs4_cb_getattr(&dp->dl_cb_fattr);
-			spin_unlock(&ctx->flc_lock);
-			wait_on_bit_timeout(&ncf->ncf_cb_flags, CB_GETATTR_BUSY,
-					TASK_INTERRUPTIBLE, NFSD_CB_GETATTR_TIMEOUT);
-			if (ncf->ncf_cb_status) {
-				/* Recall delegation only if client didn't respond */
-				status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
-				if (status != nfserr_jukebox ||
-						!nfsd_wait_for_delegreturn(rqstp, inode)) {
-					nfs4_put_stid(&dp->dl_stid);
-					return status;
-				}
-			}
-			if (!ncf->ncf_file_modified &&
-					(ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
-					ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
-				ncf->ncf_file_modified = true;
-			if (ncf->ncf_file_modified) {
-				int err;
-
-				/*
-				 * Per section 10.4.3 of RFC 8881, the server would
-				 * not update the file's metadata with the client's
-				 * modified size
-				 */
-				attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
-				attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
-				inode_lock(inode);
-				err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
-				inode_unlock(inode);
-				if (err) {
-					nfs4_put_stid(&dp->dl_stid);
-					return nfserrno(err);
-				}
-				ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
-				*size = ncf->ncf_cur_fsize;
-				*modified = true;
-			}
-			nfs4_put_stid(&dp->dl_stid);
-			return 0;
+	nfsd_stats_wdeleg_getattr_inc(nn);
+	refcount_inc(&dp->dl_stid.sc_count);
+	ncf = &dp->dl_cb_fattr;
+	nfs4_cb_getattr(&dp->dl_cb_fattr);
+	spin_unlock(&ctx->flc_lock);
+
+	wait_on_bit_timeout(&ncf->ncf_cb_flags, CB_GETATTR_BUSY,
+			    TASK_INTERRUPTIBLE, NFSD_CB_GETATTR_TIMEOUT);
+	if (ncf->ncf_cb_status) {
+		/* Recall delegation only if client didn't respond */
+		status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
+		if (status != nfserr_jukebox ||
+		    !nfsd_wait_for_delegreturn(rqstp, inode))
+			goto out_status;
+	}
+	if (!ncf->ncf_file_modified &&
+	    (ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
+	     ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
+		ncf->ncf_file_modified = true;
+	if (ncf->ncf_file_modified) {
+		int err;
+
+		/*
+		 * Per section 10.4.3 of RFC 8881, the server would
+		 * not update the file's metadata with the client's
+		 * modified size
+		 */
+		attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
+		attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
+		inode_lock(inode);
+		err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
+		inode_unlock(inode);
+		if (err) {
+			status = nfserrno(err);
+			goto out_status;
 		}
-		break;
+		ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
+		*size = ncf->ncf_cur_fsize;
+		*modified = true;
 	}
-	spin_unlock(&ctx->flc_lock);
-	return 0;
+	status = 0;
+out_status:
+	nfs4_put_stid(&dp->dl_stid);
+	return status;
 }