From: Trond Myklebust <trondmy@gmail.com>
Date: Mon, 6 Jan 2020 15:25:04 -0500
Subject: [PATCH] NFS/pnfs: Fix pnfs_generic_prepare_to_resend_writes()
Git-commit: 221203ce6406273cf00e5c6397257d986c003ee6
Patch-mainline: v5.6
References: git-fixes

Instead of making assumptions about the commit verifier contents, change
the commit code to ensure we always check that the verifier was set
by the XDR code.

Fixes: f54bcf2ecee9 ("pnfs: Prepare for flexfiles by pulling out common code")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/direct.c   |    4 ++--
 fs/nfs/nfs3xdr.c  |    5 ++++-
 fs/nfs/nfs4xdr.c  |    5 ++++-
 fs/nfs/pnfs_nfs.c |    7 +++----
 fs/nfs/write.c    |    4 +++-
 5 files changed, 16 insertions(+), 9 deletions(-)

--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -258,10 +258,10 @@ static int nfs_direct_cmp_commit_data_ve
 					 data->ds_commit_index);
 
 	/* verifier not set so always fail */
-	if (verfp->committed < 0)
+	if (verfp->committed < 0 || data->res.verf->committed <= NFS_UNSTABLE)
 		return 1;
 
-	return nfs_direct_cmp_verf(verfp, &data->verf);
+	return nfs_direct_cmp_verf(verfp, data->res.verf);
 }
 
 /**
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -2322,6 +2322,7 @@ static int nfs3_xdr_dec_commit3res(struc
 				   struct xdr_stream *xdr,
 				   struct nfs_commitres *result)
 {
+	struct nfs_writeverf *verf = result->verf;
 	enum nfs_stat status;
 	int error;
 
@@ -2334,7 +2335,9 @@ static int nfs3_xdr_dec_commit3res(struc
 	result->op_status = status;
 	if (status != NFS3_OK)
 		goto out_status;
-	error = decode_writeverf3(xdr, &result->verf->verifier);
+	error = decode_writeverf3(xdr, &verf->verifier);
+	if (!error)
+		verf->committed = NFS_FILE_SYNC;
 out:
 	return error;
 out_status:
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4317,11 +4317,14 @@ static int decode_write_verifier(struct
 
 static int decode_commit(struct xdr_stream *xdr, struct nfs_commitres *res)
 {
+	struct nfs_writeverf *verf = res->verf;
 	int status;
 
 	status = decode_op_hdr(xdr, OP_COMMIT);
 	if (!status)
-		status = decode_write_verifier(xdr, &res->verf->verifier);
+		status = decode_write_verifier(xdr, &verf->verifier);
+	if (!status)
+		verf->committed = NFS_FILE_SYNC;
 	return status;
 }
 
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -30,12 +30,11 @@ EXPORT_SYMBOL_GPL(pnfs_generic_rw_releas
 /* Fake up some data that will cause nfs_commit_release to retry the writes. */
 void pnfs_generic_prepare_to_resend_writes(struct nfs_commit_data *data)
 {
-	struct nfs_page *first = nfs_list_entry(data->pages.next);
+	struct nfs_writeverf *verf = data->res.verf;
 
 	data->task.tk_status = 0;
-	memcpy(&data->verf.verifier, &first->wb_verf,
-	       sizeof(data->verf.verifier));
-	data->verf.verifier.data[0]++; /* ensure verifier mismatch */
+	memset(&verf->verifier, 0, sizeof(verf->verifier));
+	verf->committed = NFS_UNSTABLE;
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_prepare_to_resend_writes);
 
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1827,6 +1827,7 @@ static void nfs_commit_done(struct rpc_t
 
 static void nfs_commit_release_pages(struct nfs_commit_data *data)
 {
+	const struct nfs_writeverf *verf = data->res.verf;
 	struct nfs_page	*req;
 	int status = data->task.tk_status;
 	struct nfs_commit_info cinfo;
@@ -1853,7 +1854,8 @@ static void nfs_commit_release_pages(str
 
 		/* Okay, COMMIT succeeded, apparently. Check the verifier
 		 * returned by the server against all stored verfs. */
-		if (!nfs_write_verifier_cmp(&req->wb_verf, &data->verf.verifier)) {
+		if (verf->committed > NFS_UNSTABLE &&
+		    !nfs_write_verifier_cmp(&req->wb_verf, &verf->verifier)) {
 			/* We have a match */
 			if (req->wb_page)
 				nfs_inode_remove_request(req);