From 2d23385df5f8c25d09c6d78b2a9042ff881d9f89 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Tue, 24 Aug 2021 22:36:03 -0400
Subject: [PATCH] nfsd: fix crash on LOCKT on reexported NFSv3
Git-commit: 0bcc7ca40bd823193224e9f38bafbd8325aaf566
Patch-mainline: v5.15-rc1
References: stable-5.14.6

[ Upstream commit 0bcc7ca40bd823193224e9f38bafbd8325aaf566 ]

Unlike other filesystems, NFSv3 tries to use fl_file in the GETLK case.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 fs/nfsd/nfs4state.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d0b2041c4d75..3d805f5b1f5d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7040,8 +7040,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 /*
  * The NFSv4 spec allows a client to do a LOCKT without holding an OPEN,
  * so we do a temporary open here just to get an open file to pass to
- * vfs_test_lock.  (Arguably perhaps test_lock should be done with an
- * inode operation.)
+ * vfs_test_lock.
  */
 static __be32 nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
 {
@@ -7056,7 +7055,9 @@ static __be32 nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct
 							NFSD_MAY_READ));
 	if (err)
 		goto out;
+	lock->fl_file = nf->nf_file;
 	err = nfserrno(vfs_test_lock(nf->nf_file, lock));
+	lock->fl_file = NULL;
 out:
 	fh_unlock(fhp);
 	nfsd_file_put(nf);
-- 
2.26.2