NFSD: Rework encoding and decoding of nfsd4_deviceid

[ Upstream commit 832738e4b325b742940761e10487403f9aad13e8 ]

Compilers may optimize the layout of C structures, so we should not rely
on sizeof struct and memcpy to encode and decode XDR structures. The byte
order of the fields should also be taken into account.

This patch adds the correct functions to handle the deviceid4 structure
and removes the pad field, which is currently not used by NFSD, from the
runtime state. The server's byte order is preserved because the deviceid4
blob on the wire is only used as a cookie by the client.

Signed-off-by: Sergey Bashirov <sergeybashirov@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Stable-dep-of: d68886bae76a ("NFSD: Fix last write offset handling in layoutcommit")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

5 files changed, 39 insertions, 22 deletions

diff --git a/fs/nfsd/blocklayoutxdr.c b/fs/nfsd/blocklayoutxdr.c
index 1ed2f691ebb9..dd35c472eb37 100644
--- a/fs/nfsd/blocklayoutxdr.c
+++ b/fs/nfsd/blocklayoutxdr.c
@@ -29,8 +29,7 @@ nfsd4_block_encode_layoutget(struct xdr_stream *xdr,
 	*p++ = cpu_to_be32(len);
 	*p++ = cpu_to_be32(1);		/* we always return a single extent */
 
-	p = xdr_encode_opaque_fixed(p, &b->vol_id,
-			sizeof(struct nfsd4_deviceid));
+	p = svcxdr_encode_deviceid4(p, &b->vol_id);
 	p = xdr_encode_hyper(p, b->foff);
 	p = xdr_encode_hyper(p, b->len);
 	p = xdr_encode_hyper(p, b->soff);
@@ -145,9 +144,7 @@ nfsd4_block_decode_layoutupdate(__be32 *p, u32 len, struct iomap **iomapp,
 	for (i = 0; i < nr_iomaps; i++) {
 		struct pnfs_block_extent bex;
 
-		memcpy(&bex.vol_id, p, sizeof(struct nfsd4_deviceid));
-		p += XDR_QUADLEN(sizeof(struct nfsd4_deviceid));
-
+		p = svcxdr_decode_deviceid4(p, &bex.vol_id);
 		p = xdr_decode_hyper(p, &bex.foff);
 		if (bex.foff & (block_size - 1)) {
 			dprintk("%s: unaligned offset 0x%llx\n",
diff --git a/fs/nfsd/flexfilelayoutxdr.c b/fs/nfsd/flexfilelayoutxdr.c
index bb205328e043..223a10f37898 100644
--- a/fs/nfsd/flexfilelayoutxdr.c
+++ b/fs/nfsd/flexfilelayoutxdr.c
@@ -54,8 +54,7 @@ nfsd4_ff_encode_layoutget(struct xdr_stream *xdr,
 	*p++ = cpu_to_be32(1);			/* single mirror */
 	*p++ = cpu_to_be32(1);			/* single data server */
 
-	p = xdr_encode_opaque_fixed(p, &fl->deviceid,
-			sizeof(struct nfsd4_deviceid));
+	p = svcxdr_encode_deviceid4(p, &fl->deviceid);
 
 	*p++ = cpu_to_be32(1);			/* efficiency */
 
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index e8a80052cb1b..308214378fd3 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -120,7 +120,6 @@ nfsd4_set_deviceid(struct nfsd4_deviceid *id, const struct svc_fh *fhp,
 
 	id->fsid_idx = fhp->fh_export->ex_devid_map->idx;
 	id->generation = device_generation;
-	id->pad = 0;
 	return 0;
 }
 
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 071c8103f6c3..5073fa77cd76 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -566,18 +566,6 @@ nfsd4_decode_state_owner4(struct nfsd4_compoundargs *argp,
 }
 
 #ifdef CONFIG_NFSD_PNFS
-static __be32
-nfsd4_decode_deviceid4(struct nfsd4_compoundargs *argp,
-		       struct nfsd4_deviceid *devid)
-{
-	__be32 *p;
-
-	p = xdr_inline_decode(argp->xdr, NFS4_DEVICEID4_SIZE);
-	if (!p)
-		return nfserr_bad_xdr;
-	memcpy(devid, p, sizeof(*devid));
-	return nfs_ok;
-}
 
 static __be32
 nfsd4_decode_layoutupdate4(struct nfsd4_compoundargs *argp,
@@ -1733,7 +1721,7 @@ nfsd4_decode_getdeviceinfo(struct nfsd4_compoundargs *argp,
 	__be32 status;
 
 	memset(gdev, 0, sizeof(*gdev));
-	status = nfsd4_decode_deviceid4(argp, &gdev->gd_devid);
+	status = nfsd4_decode_deviceid4(argp->xdr, &gdev->gd_devid);
 	if (status)
 		return status;
 	if (xdr_stream_decode_u32(argp->xdr, &gdev->gd_layout_type) < 0)
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 9bd1ade6ba54..c2765619edd4 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -459,9 +459,43 @@ struct nfsd4_reclaim_complete {
 struct nfsd4_deviceid {
 	u64			fsid_idx;
 	u32			generation;
-	u32			pad;
 };
 
+static inline __be32 *
+svcxdr_encode_deviceid4(__be32 *p, const struct nfsd4_deviceid *devid)
+{
+	__be64 *q = (__be64 *)p;
+
+	*q = (__force __be64)devid->fsid_idx;
+	p += 2;
+	*p++ = (__force __be32)devid->generation;
+	*p++ = xdr_zero;
+	return p;
+}
+
+static inline __be32 *
+svcxdr_decode_deviceid4(__be32 *p, struct nfsd4_deviceid *devid)
+{
+	__be64 *q = (__be64 *)p;
+
+	devid->fsid_idx = (__force u64)(*q);
+	p += 2;
+	devid->generation = (__force u32)(*p++);
+	p++; /* NFSD does not use the remaining octets */
+	return p;
+}
+
+static inline __be32
+nfsd4_decode_deviceid4(struct xdr_stream *xdr, struct nfsd4_deviceid *devid)
+{
+	__be32 *p = xdr_inline_decode(xdr, NFS4_DEVICEID4_SIZE);
+
+	if (unlikely(!p))
+		return nfserr_bad_xdr;
+	svcxdr_decode_deviceid4(p, devid);
+	return nfs_ok;
+}
+
 struct nfsd4_layout_seg {
 	u32			iomode;
 	u64			offset;