[PATCH 6.6 076/105] NFSD: Rework encoding and decoding of nfsd4_deviceid

Greg Kroah-Hartman
2025-10-21T19:56:11Z

From: Sergey Bashirov <sergeybashirov@gmail.com>

[ 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>
---
fs/nfsd/blocklayoutxdr.c | 7 ++-----
fs/nfsd/flexfilelayoutxdr.c | 3 +--
fs/nfsd/nfs4layouts.c | 1 -
fs/nfsd/nfs4xdr.c | 14 +-------------
fs/nfsd/xdr4.h | 36 +++++++++++++++++++++++++++++++++++-
5 files changed, 39 insertions(+), 22 deletions(-)

--- a/fs/nfsd/blocklayoutxdr.c
+++ b/fs/nfsd/blocklayoutxdr.c
@@ -29,8 +29,7 @@ nfsd4_block_encode_layoutget(struct 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 *
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",
--- a/fs/nfsd/flexfilelayoutxdr.c
+++ b/fs/nfsd/flexfilelayoutxdr.c
@@ -54,8 +54,7 @@ nfsd4_ff_encode_layoutget(struct xdr_str
*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 */

--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -120,7 +120,6 @@ nfsd4_set_deviceid(struct nfsd4_deviceid

id->fsid_idx = fhp->fh_export->ex_devid_map->idx;
id->generation = device_generation;
- id->pad = 0;
return 0;
}

--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -566,18 +566,6 @@ nfsd4_decode_state_owner4(struct nfsd4_c
}

#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_
__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)
--- 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;