On Sep 25, 2008, at 1:35 PM, Peter Staubach wrote:
Chuck Lever wrote:
The sc_name field is currently 56 bytes long. This is not large
enough
to hold a pair of IPv6 addresses, the authentication type, the
protocol
name, and a uniquifier number. The maximum possible size of the name
string using IPv6 addresses is just under 110 bytes, so I increased
the
size of the sc_name field to accomodate this maximum.
In addition, the strings in the nfs4_setclientid structure are
constructed with scnprintf(), which wants to terminate its output
with
'\0'. The sc_netid field was large enough only for a three byte
netid
string and a '\0' so inet6 netids were being truncated. Perhaps we
don't need the overhead of scnprintf() to do a simple string copy,
but
I fixed this by increasing the size of the buffer by one byte.
Since all three of the string buffers in nfs4_setclientid are
constructed with scnprintf(), I increased the size of all three by
one
byte to document the requirement, although I don't think either the
universal address field or the name field will be so small that these
strings get truncated in this way.
The size of the Linux client's client ID on the wire will be larger
than before. RFC 3530 suggests the size limit for client IDs is
1024,
and we are still well below that.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/linux/nfs_xdr.h | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 8c77c11..dc34977 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -672,16 +672,16 @@ struct nfs4_rename_res {
struct nfs_fattr * new_fattr;
};
-#define NFS4_SETCLIENTID_NAMELEN (56)
+#define NFS4_SETCLIENTID_NAMELEN (128)
Perhaps (127) might have been a better choice here? In the
struct below, the arrays end up being allocated to (128) + 1
plus whatever alignment bytes are valid for the platform.
This wastes a fair amount of space.
Probably the worst alignment padding would be 7 bytes. The struct is
already large, and is only used once on the stack just after mounting,
so I'm not that concerned. I would rather have a little extra here
than not enough.
However, we can trim the length of the name a little. I counted about
105 characters maximum in my simple calculations. We could probably
make it (111) to round out the field to 112 bytes (divisible by 8).
ps
struct nfs4_setclientid {
const nfs4_verifier * sc_verifier;
unsigned int sc_name_len;
- char sc_name[NFS4_SETCLIENTID_NAMELEN];
+ char sc_name[NFS4_SETCLIENTID_NAMELEN + 1];
u32 sc_prog;
unsigned int sc_netid_len;
- char sc_netid[RPCBIND_MAXNETIDLEN];
+ char sc_netid[RPCBIND_MAXNETIDLEN + 1];
unsigned int sc_uaddr_len;
- char sc_uaddr[RPCBIND_MAXUADDRLEN];
+ char sc_uaddr[RPCBIND_MAXUADDRLEN + 1];
u32 sc_cb_ident;
};
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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