From b0f33732796b45d7833257ea30d56de42bf80403 Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
Date: Mon, 6 Mar 2023 10:43:47 -0500
Subject: [PATCH] NFSD: Protect against filesystem freezing

[ Upstream commit fd9a2e1d513823e840960cb3bc26d8b7749d4ac2 ]

Flole observes this WARNING on occasion:

[1210423.486503] WARNING: CPU: 8 PID: 1524732 at fs/ext4/ext4_jbd2.c:75 ext4_journal_check_start+0x68/0xb0

Reported-by: <flole@flole.de>
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217123
Fixes: 73da852e3831 ("nfsd: use vfs_iter_read/write")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfsd/vfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 3d67dd7eab4b..ddf424d76d41 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1117,7 +1117,9 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	since = READ_ONCE(file->f_wb_err);
 	if (verf)
 		nfsd_copy_write_verifier(verf, nn);
+	file_start_write(file);
 	host_err = vfs_iter_write(file, &iter, &pos, flags);
+	file_end_write(file);
 	if (host_err < 0) {
 		nfsd_reset_write_verifier(nn);
 		trace_nfsd_writeverf_reset(nn, rqstp, host_err);