linux-kernel - [PATCH] NFSD: Change ret code of xdr_stream_decode_opaque

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Message-ID: <20250717194838.69200-1-sergeybashirov@gmail.com>
Date: Thu, 17 Jul 2025 22:48:30 +0300
From: Sergey Bashirov <sergeybashirov@...il.com>
To: Chuck Lever <chuck.lever@...cle.com>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Jeff Layton <jlayton@...nel.org>,
	NeilBrown <neil@...wn.name>,
	Olga Kornievskaia <okorniev@...hat.com>,
	Dai Ngo <Dai.Ngo@...cle.com>,
	Tom Talpey <tom@...pey.com>
Cc: linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sergey Bashirov <sergeybashirov@...il.com>
Subject: [PATCH] NFSD: Change ret code of xdr_stream_decode_opaque_fixed

Since the XDR field is fixed in size, the caller already knows how many
bytes were decoded, on success. Thus, xdr_stream_decode_opaque_fixed()
doesn't need to return that value. And, xdr_stream_decode_u32 and _u64
both return zero on success.

This patch also simplifies the error checking to avoid potential integer
promotion issues.

Signed-off-by: Sergey Bashirov <sergeybashirov@...il.com>
---
 fs/nfsd/blocklayoutxdr.c                                      | 2 +-
 include/linux/nfs_xdr.h                                       | 2 +-
 include/linux/sunrpc/xdr.h                                    | 4 ++--
 .../xdrgen/templates/C/pointer/decoder/fixed_length_opaque.j2 | 2 +-
 .../xdrgen/templates/C/struct/decoder/fixed_length_opaque.j2  | 2 +-
 .../xdrgen/templates/C/typedef/decoder/fixed_length_opaque.j2 | 2 +-
 6 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/nfsd/blocklayoutxdr.c b/fs/nfsd/blocklayoutxdr.c
index 266b2737882e1..2a4dcb428d823 100644
--- a/fs/nfsd/blocklayoutxdr.c
+++ b/fs/nfsd/blocklayoutxdr.c
@@ -157,7 +157,7 @@ nfsd4_block_decode_layoutupdate(struct xdr_stream *xdr, struct iomap **iomapp,
 
 		ret = xdr_stream_decode_opaque_fixed(xdr,
 				&bex.vol_id, sizeof(bex.vol_id));
-		if (ret < sizeof(bex.vol_id)) {
+		if (ret) {
 			nfserr = nfserr_bad_xdr;
 			goto fail;
 		}
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 67f6632f723b4..dd80163e0140c 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1863,7 +1863,7 @@ static inline int decode_opaque_fixed(struct xdr_stream *xdr,
 				      void *buf, size_t len)
 {
 	ssize_t ret = xdr_stream_decode_opaque_fixed(xdr, buf, len);
-	if (unlikely(ret < 0))
+	if (unlikely(ret))
 		return -EIO;
 	return 0;
 }
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index e3358c630ba18..ffb699a02b17d 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -730,7 +730,7 @@ xdr_stream_decode_u64(struct xdr_stream *xdr, __u64 *ptr)
  * @len: size of buffer pointed to by @ptr
  *
  * Return values:
- *   On success, returns size of object stored in @ptr
+ *   %0 on success
  *   %-EBADMSG on XDR buffer overflow
  */
 static inline ssize_t
@@ -741,7 +741,7 @@ xdr_stream_decode_opaque_fixed(struct xdr_stream *xdr, void *ptr, size_t len)
 	if (unlikely(!p))
 		return -EBADMSG;
 	xdr_decode_opaque_fixed(p, ptr, len);
-	return len;
+	return 0;
 }
 
 /**
diff --git a/tools/net/sunrpc/xdrgen/templates/C/pointer/decoder/fixed_length_opaque.j2 b/tools/net/sunrpc/xdrgen/templates/C/pointer/decoder/fixed_length_opaque.j2
index b4695ece1884b..ea9295f91aecc 100644
--- a/tools/net/sunrpc/xdrgen/templates/C/pointer/decoder/fixed_length_opaque.j2
+++ b/tools/net/sunrpc/xdrgen/templates/C/pointer/decoder/fixed_length_opaque.j2
@@ -2,5 +2,5 @@
 {% if annotate %}
 	/* member {{ name }} (fixed-length opaque) */
 {% endif %}
-	if (xdr_stream_decode_opaque_fixed(xdr, ptr->{{ name }}, {{ size }}) < 0)
+	if (xdr_stream_decode_opaque_fixed(xdr, ptr->{{ name }}, {{ size }}) != 0)
 		return false;
diff --git a/tools/net/sunrpc/xdrgen/templates/C/struct/decoder/fixed_length_opaque.j2 b/tools/net/sunrpc/xdrgen/templates/C/struct/decoder/fixed_length_opaque.j2
index b4695ece1884b..ea9295f91aecc 100644
--- a/tools/net/sunrpc/xdrgen/templates/C/struct/decoder/fixed_length_opaque.j2
+++ b/tools/net/sunrpc/xdrgen/templates/C/struct/decoder/fixed_length_opaque.j2
@@ -2,5 +2,5 @@
 {% if annotate %}
 	/* member {{ name }} (fixed-length opaque) */
 {% endif %}
-	if (xdr_stream_decode_opaque_fixed(xdr, ptr->{{ name }}, {{ size }}) < 0)
+	if (xdr_stream_decode_opaque_fixed(xdr, ptr->{{ name }}, {{ size }}) != 0)
 		return false;
diff --git a/tools/net/sunrpc/xdrgen/templates/C/typedef/decoder/fixed_length_opaque.j2 b/tools/net/sunrpc/xdrgen/templates/C/typedef/decoder/fixed_length_opaque.j2
index 8b4ff08c49e5e..bdc7bd24ffb13 100644
--- a/tools/net/sunrpc/xdrgen/templates/C/typedef/decoder/fixed_length_opaque.j2
+++ b/tools/net/sunrpc/xdrgen/templates/C/typedef/decoder/fixed_length_opaque.j2
@@ -13,5 +13,5 @@ xdrgen_decode_{{ name }}(struct xdr_stream *xdr, {{ classifier }}{{ name }} *ptr
 {% if annotate %}
 	/* (fixed-length opaque) */
 {% endif %}
-	return xdr_stream_decode_opaque_fixed(xdr, ptr, {{ size }}) >= 0;
+	return xdr_stream_decode_opaque_fixed(xdr, ptr, {{ size }}) == 0;
 };
-- 
2.43.0