From: Chuck Lever <chuck.lever@xxxxxxxxxx>
The XDR specification in RFC 8881 looks like this:
struct device_addr4 {
layouttype4 da_layout_type;
opaque da_addr_body<>;
};
struct GETDEVICEINFO4resok {
device_addr4 gdir_device_addr;
bitmap4 gdir_notification;
};
union GETDEVICEINFO4res switch (nfsstat4 gdir_status) {
case NFS4_OK:
GETDEVICEINFO4resok gdir_resok4;
case NFS4ERR_TOOSMALL:
count4 gdir_mincount;
default:
void;
};
Looking at nfsd4_encode_getdeviceinfo() ....
When the client provides a zero gd_maxcount, then the Linux NFS
server implementation encodes the da_layout_type field and then
skips the da_addr_body field completely, proceeding directly to
encode gdir_notification field.
There does not appear to be an option in the specification to skip
encoding da_addr_body. Moreover, Section 18.40.3 says:
> If the client wants to just update or turn off notifications, it
> MAY send a GETDEVICEINFO operation with gdia_maxcount set to zero.
> In that event, if the device ID is valid, the reply's da_addr_body
> field of the gdir_device_addr field will be of zero length.
Since the layout drivers are responsible for encoding the
da_addr_body field, put this fix inside the ->encode_getdeviceinfo
methods.
Fixes: 9cf514ccfacb ("nfsd: implement pNFS operations")
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Tom Haynes <logyr@xxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/blocklayoutxdr.c | 9 +++++++++
fs/nfsd/flexfilelayoutxdr.c | 9 +++++++++
fs/nfsd/nfs4xdr.c | 25 +++++++++++--------------
3 files changed, 29 insertions(+), 14 deletions(-)
diff --git a/fs/nfsd/blocklayoutxdr.c b/fs/nfsd/blocklayoutxdr.c
index 8e9c1a0f8d38..1ed2f691ebb9 100644
--- a/fs/nfsd/blocklayoutxdr.c
+++ b/fs/nfsd/blocklayoutxdr.c
@@ -83,6 +83,15 @@ nfsd4_block_encode_getdeviceinfo(struct xdr_stream *xdr,
int len = sizeof(__be32), ret, i;
__be32 *p;
+ /*
+ * See paragraph 5 of RFC 8881 S18.40.3.
+ */
+ if (!gdp->gd_maxcount) {
+ if (xdr_stream_encode_u32(xdr, 0) != XDR_UNIT)
+ return nfserr_resource;
+ return nfs_ok;
+ }
+
p = xdr_reserve_space(xdr, len + sizeof(__be32));
if (!p)
return nfserr_resource;
diff --git a/fs/nfsd/flexfilelayoutxdr.c b/fs/nfsd/flexfilelayoutxdr.c
index e81d2a5cf381..bb205328e043 100644
--- a/fs/nfsd/flexfilelayoutxdr.c
+++ b/fs/nfsd/flexfilelayoutxdr.c
@@ -85,6 +85,15 @@ nfsd4_ff_encode_getdeviceinfo(struct xdr_stream *xdr,
int addr_len;
__be32 *p;
+ /*
+ * See paragraph 5 of RFC 8881 S18.40.3.
+ */
+ if (!gdp->gd_maxcount) {
+ if (xdr_stream_encode_u32(xdr, 0) != XDR_UNIT)
+ return nfserr_resource;
+ return nfs_ok;
+ }
+
/* len + padding for two strings */
addr_len = 16 + da->netaddr.netid_len + da->netaddr.addr_len;
ver_len = 20;
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index d4de39404cde..2e40c74d2f72 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4686,20 +4686,17 @@ nfsd4_encode_getdeviceinfo(struct nfsd4_compoundres *resp, __be32 nfserr,
*p++ = cpu_to_be32(gdev->gd_layout_type);
- /* If maxcount is 0 then just update notifications */
- if (gdev->gd_maxcount != 0) {
- ops = nfsd4_layout_ops[gdev->gd_layout_type];
- nfserr = ops->encode_getdeviceinfo(xdr, gdev);
- if (nfserr) {
- /*
- * We don't bother to burden the layout drivers with
- * enforcing gd_maxcount, just tell the client to
- * come back with a bigger buffer if it's not enough.
- */
- if (xdr->buf->len + 4 > gdev->gd_maxcount)
- goto toosmall;
- return nfserr;
- }
+ ops = nfsd4_layout_ops[gdev->gd_layout_type];
+ nfserr = ops->encode_getdeviceinfo(xdr, gdev);
+ if (nfserr) {
+ /*
+ * We don't bother to burden the layout drivers with
+ * enforcing gd_maxcount, just tell the client to
+ * come back with a bigger buffer if it's not enough.
+ */
+ if (xdr->buf->len + 4 > gdev->gd_maxcount)
+ goto toosmall;
+ return nfserr;
}
if (gdev->gd_notify_types) {
