[PATCH] NFSD: Protect against filesystem freezing

---
 fs/nfsd/vfs.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 21d5209f6e04..ba34a31a7c70 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c

@@ -1104,7 +1104,9 @@ 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);

From: Chuck Lever <redacted>

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: <redacted>
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")
Signed-off-by: Chuck Lever <redacted>
---
 fs/nfsd/vfs.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 21d5209f6e04..ba34a31a7c70 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c

@@ -1104,7 +1104,9 @@ 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);