Re: [PATCH 2/6] nfsd: release path refs on follow_down() error

[Al Viro <viro@zeniv.linux.org.uk>]

On Mon, Jun 01, 2026 at 02:57:16PM -0400, Jeff Layton wrote:

> Looks reasonable. Chuck has already taken this patch into his tree, but
> we could do a cleanup on top. Want to send us an "official" patch?

Not a problem, but it's completely untested.  It compiles, but...

unify cleanups in nfsd_cross_mnt() exits

Instead of having a separate path_put() on each failure exit, as well as
on the normal path, let's move all of those past the point where these
codepaths join.  We want to keep the ordering between path_put() and
exp_put(), so move that one as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 95ce15440492..cfac0cc4207c 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -137,20 +137,19 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
 		follow_flags = LOOKUP_AUTOMOUNT;
 
 	err = follow_down(&path, follow_flags);
-	if (err < 0) {
-		path_put(&path);
+	if (err < 0)
 		goto out;
-	}
+
 	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
 	    nfsd_mountpoint(dentry, exp) == 2) {
 		/* This is only a mountpoint in some other namespace */
-		path_put(&path);
 		goto out;
 	}
 
 	exp2 = rqst_exp_get_by_name(rqstp, &path);
 	if (IS_ERR(exp2)) {
 		err = PTR_ERR(exp2);
+		exp2 = NULL;
 		/*
 		 * We normally allow NFS clients to continue
 		 * "underneath" a mountpoint that is not exported.
@@ -160,10 +159,7 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
 		 */
 		if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
 			err = 0;
-		path_put(&path);
-		goto out;
-	}
-	if (nfsd_v4client(rqstp) ||
+	} else if (nfsd_v4client(rqstp) ||
 		(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
 		/* successfully crossed mount point */
 		/*
@@ -177,9 +173,10 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
 		*expp = exp2;
 		exp2 = exp;
 	}
-	path_put(&path);
-	exp_put(exp2);
 out:
+	path_put(&path);
+	if (exp2)
+		exp_put(exp2);
 	return err;
 }