nfsd41: CREATE_EXCLUSIVE4_1

Implement the CREATE_EXCLUSIVE4_1 open mode conforming to
http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-26

This mode allows the client to atomically create a file
if it doesn't exist while setting some of its attributes.

It must be implemented if the server supports persistent
reply cache and/or pnfs.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

4 files changed, 43 insertions, 7 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index e206053433e3..b2883e9c6381 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -93,6 +93,21 @@ do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_o
         open->op_truncate = 0;
 
         if (open->op_create) {
+                /* FIXME: check session persistence and pnfs flags.
+                 * The nfsv4.1 spec requires the following semantics:
+                 *
+                 * Persistent   | pNFS   | Server REQUIRED | Client Allowed
+                 * Reply Cache  | server |                 |
+                 * -------------+--------+-----------------+--------------------
+                 * no           | no     | EXCLUSIVE4_1    | EXCLUSIVE4_1
+                 *              |        |                 | (SHOULD)
+                 *              |        | and EXCLUSIVE4  | or EXCLUSIVE4
+                 *              |        |                 | (SHOULD NOT)
+                 * no           | yes    | EXCLUSIVE4_1    | EXCLUSIVE4_1
+                 * yes          | no     | GUARDED4        | GUARDED4
+                 * yes          | yes    | GUARDED4        | GUARDED4
+                 */
+
                 /*
                  * Note: create modes (UNCHECKED,GUARDED...) are the same
                  * in NFSv4 as in v3.
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 533d14fec99e..b820c311931c 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -260,6 +260,12 @@ static u32 nfsd_attrmask[] = {
         NFSD_WRITEABLE_ATTRS_WORD2
 };
 
+static u32 nfsd41_ex_attrmask[] = {
+        NFSD_SUPPATTR_EXCLCREAT_WORD0,
+        NFSD_SUPPATTR_EXCLCREAT_WORD1,
+        NFSD_SUPPATTR_EXCLCREAT_WORD2
+};
+
 static __be32
 nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval, u32 *writable,
                    struct iattr *iattr, struct nfs4_acl **acl)
@@ -684,6 +690,17 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
                         READ_BUF(8);
                         COPYMEM(open->op_verf.data, 8);
                         break;
+                case NFS4_CREATE_EXCLUSIVE4_1:
+                        if (argp->minorversion < 1)
+                                goto xdr_error;
+                        READ_BUF(8);
+                        COPYMEM(open->op_verf.data, 8);
+                        status = nfsd4_decode_fattr(argp, open->op_bmval,
+                                nfsd41_ex_attrmask, &open->op_iattr,
+                                &open->op_acl);
+                        if (status)
+                                goto out;
+                        break;
                 default:
                         goto xdr_error;
                 }
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index ec3cd49b04f5..e3f0cbcbd0db 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -368,7 +368,13 @@ enum opentype4 {
 enum createmode4 {
         NFS4_CREATE_UNCHECKED = 0,
         NFS4_CREATE_GUARDED = 1,
-        NFS4_CREATE_EXCLUSIVE = 2
+        NFS4_CREATE_EXCLUSIVE = 2,
+        /*
+         * New to NFSv4.1. If session is persistent,
+         * GUARDED4 MUST be used. Otherwise, use
+         * EXCLUSIVE4_1 instead of EXCLUSIVE4.
+         */
+        NFS4_CREATE_EXCLUSIVE4_1 = 3
 };
 
 enum limit_by4 {
diff --git a/include/linux/nfsd/xdr4.h b/include/linux/nfsd/xdr4.h
index c07d8fe7bb07..f80d6013fdc3 100644
--- a/include/linux/nfsd/xdr4.h
+++ b/include/linux/nfsd/xdr4.h
@@ -219,10 +219,8 @@ struct nfsd4_open {
         u32             op_create;          /* request */
         u32             op_createmode;      /* request */
         u32             op_bmval[3];        /* request */
-        union {                             /* request */
-                struct iattr    iattr;                      /* UNCHECKED4,GUARDED4 */
-                nfs4_verifier   verf;                                /* EXCLUSIVE4 */
-        } u;
+        struct iattr    iattr;              /* UNCHECKED4, GUARDED4, EXCLUSIVE4_1 */
+        nfs4_verifier   verf;               /* EXCLUSIVE4 */
         clientid_t      op_clientid;        /* request */
         struct xdr_netobj op_owner;           /* request */
         u32             op_seqid;           /* request */
@@ -236,8 +234,8 @@ struct nfsd4_open {
         struct nfs4_stateowner *op_stateowner; /* used during processing */
         struct nfs4_acl *op_acl;
 };
-#define op_iattr        u.iattr
-#define op_verf         u.verf
+#define op_iattr        iattr
+#define op_verf         verf
 
 struct nfsd4_open_confirm {
         stateid_t       oc_req_stateid          /* request */;