[PATCH] kNFSd: nfsd4 xdr name encoding improvements

Encode names directly into xdr buffer; this optimizes out a data copy, reduces
stack usage, and will make life simpler when doing acls.

From: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index bb0c72fc7ff61cf7e703f1a72e885ba87708335d..d810fd11d702815cf56995b10c8bffee1dde68ea 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1289,6 +1289,49 @@ static u32 nfs4_ftypes[16] = {
         NF4SOCK, NF4BAD,  NF4LNK, NF4BAD,
 };
 
+static inline int
+xdr_padding(int l)
+{
+       return 3 - ((l - 1) & 3); /* smallest i>=0 such that (l+i)%4 = 0 */
+}
+
+static int
+nfsd4_encode_name(struct svc_rqst *rqstp, int group, uid_t id,
+                       u32 **p, int *buflen)
+{
+       int status;
+       u32 len;
+
+       if (*buflen < (XDR_QUADLEN(IDMAP_NAMESZ) << 2) + 4)
+               return nfserr_resource;
+       if (group)
+               status = nfsd_map_gid_to_name(rqstp, id, (u8 *)(*p + 1));
+       else
+               status = nfsd_map_uid_to_name(rqstp, id, (u8 *)(*p + 1));
+       if (status < 0)
+               return nfserrno(status);
+       len = (unsigned)status;
+       *(*p)++ = htonl(len);
+       memset((u8 *)*p + len, 0, xdr_padding(len));
+       *p += XDR_QUADLEN(len);
+       *buflen -= (XDR_QUADLEN(len) << 2) + 4;
+       BUG_ON(*buflen < 0);
+       return 0;
+}
+
+static inline int
+nfsd4_encode_user(struct svc_rqst *rqstp, uid_t uid, u32 **p, int *buflen)
+{
+       return nfsd4_encode_name(rqstp, uid, 0, p, buflen);
+}
+
+static inline int
+nfsd4_encode_group(struct svc_rqst *rqstp, uid_t gid, u32 **p, int *buflen)
+{
+       return nfsd4_encode_name(rqstp, gid, 1, p, buflen);
+}
+
+
 /*
  * Note: @fhp can be NULL; in this case, we might have to compose the filehandle
  * ourselves.
@@ -1304,10 +1347,6 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
        u32 bmval0 = bmval[0];
        u32 bmval1 = bmval[1];
        struct kstat stat;
-       char owner[IDMAP_NAMESZ];
-       u32 ownerlen = 0;
-       char group[IDMAP_NAMESZ];
-       u32 grouplen = 0;
        struct svc_fh tempfh;
        struct kstatfs statfs;
        int buflen = *countp << 2;
@@ -1338,23 +1377,6 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
                        goto out;
                fhp = &tempfh;
        }
-       if (bmval1 & FATTR4_WORD1_OWNER) {
-               int temp = nfsd_map_uid_to_name(rqstp, stat.uid, owner);
-               if (temp < 0) {
-                       status = temp;
-                       goto out_nfserr;
-               }
-               ownerlen = (unsigned) temp;
-       }
-       if (bmval1 & FATTR4_WORD1_OWNER_GROUP) {
-               int temp = nfsd_map_gid_to_name(rqstp, stat.gid, group);
-               if (temp < 0) {
-                       status = temp;
-                       goto out_nfserr;
-               }
-               grouplen = (unsigned) temp;
-       }
-
        if ((buflen -= 16) < 0)
                goto out_resource;
 
@@ -1536,18 +1558,18 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
                WRITE32(stat.nlink);
        }
        if (bmval1 & FATTR4_WORD1_OWNER) {
-               buflen -= (XDR_QUADLEN(ownerlen) << 2) + 4;
-               if (buflen < 0)
+               status = nfsd4_encode_user(rqstp, stat.uid, &p, &buflen);
+               if (status == nfserr_resource)
                        goto out_resource;
-               WRITE32(ownerlen);
-               WRITEMEM(owner, ownerlen);
+               if (status)
+                       goto out;
        }
        if (bmval1 & FATTR4_WORD1_OWNER_GROUP) {
-               buflen -= (XDR_QUADLEN(grouplen) << 2) + 4;
-               if (buflen < 0)
+               status = nfsd4_encode_group(rqstp, stat.gid, &p, &buflen);
+               if (status == nfserr_resource)
                        goto out_resource;
-               WRITE32(grouplen);
-               WRITEMEM(group, grouplen);
+               if (status)
+                       goto out;
        }
        if (bmval1 & FATTR4_WORD1_RAWDEV) {
                if ((buflen -= 8) < 0)