NFS: change stateid to be a union

In NFSv4.1 the stateid consists of the other and seqid fields. For layout
processing we need to numerically compare the seqid value of layout stateids.
To do so, introduce a union to nfs4_stateid to switch between opaque(16 bytes)
and opaque(12 bytes) / __be32

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 17 insertions, 6 deletions

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 930d10fecda..2950fca0c61 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -118,11 +118,11 @@ int nfs41_validate_delegation_stateid(struct nfs_delegation *delegation, const n
         if (delegation == NULL)
                 return 0;
 
-        /* seqid is 4-bytes long */
-        if (((u32 *) &stateid->data)[0] != 0)
+        if (stateid->stateid.seqid != 0)
                 return 0;
-        if (memcmp(&delegation->stateid.data[4], &stateid->data[4],
-                   sizeof(stateid->data)-4))
+        if (memcmp(&delegation->stateid.stateid.other,
+                   &stateid->stateid.other,
+                   NFS4_STATEID_OTHER_SIZE))
                 return 0;
 
         return 1;
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 6c0406e87d5..34da32436ac 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -17,7 +17,9 @@
 
 #define NFS4_BITMAP_SIZE        2
 #define NFS4_VERIFIER_SIZE      8
-#define NFS4_STATEID_SIZE       16
+#define NFS4_STATEID_SEQID_SIZE 4
+#define NFS4_STATEID_OTHER_SIZE 12
+#define NFS4_STATEID_SIZE       (NFS4_STATEID_SEQID_SIZE + NFS4_STATEID_OTHER_SIZE)
 #define NFS4_FHSIZE             128
 #define NFS4_MAXPATHLEN         PATH_MAX
 #define NFS4_MAXNAMLEN          NAME_MAX
@@ -167,7 +169,16 @@ struct nfs4_acl {
 };
 
 typedef struct { char data[NFS4_VERIFIER_SIZE]; } nfs4_verifier;
-typedef struct { char data[NFS4_STATEID_SIZE]; } nfs4_stateid;
+
+struct nfs41_stateid {
+        __be32 seqid;
+        char other[NFS4_STATEID_OTHER_SIZE];
+} __attribute__ ((packed));
+
+typedef union {
+        char data[NFS4_STATEID_SIZE];
+        struct nfs41_stateid stateid;
+} nfs4_stateid;
 
 enum nfs_opnum4 {
         OP_ACCESS = 3,