NFS: Now that file handle comparison ignores the unused parts of the

   file handle container, there is no longer any need to clear the
   file handle container before copying in a file handle.  This
   allows us to remove a 128 byte memset() from several hot paths.
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>

fs/nfs/inode.c

@@ -607,11 +607,10 @@ static int
 nfs_init_locked(struct inode *inode, void *opaque)
 {
 	struct nfs_find_desc	*desc = (struct nfs_find_desc *)opaque;
-	struct nfs_fh		*fh = desc->fh;
 	struct nfs_fattr	*fattr = desc->fattr;
 
 	NFS_FILEID(inode) = fattr->fileid;
-	memcpy(NFS_FH(inode), fh, sizeof(struct nfs_fh));
+	nfs_copy_fh(NFS_FH(inode), desc->fh);
 	return 0;
 }
 
@@ -1284,9 +1283,7 @@ static struct super_block *nfs_get_sb(struct file_system_type *fs_type,
 	init_nfsv4_state(server);
 
 	root = &server->fh;
-	memcpy(root, &data->root, sizeof(*root));
-	if (root->size < sizeof(root->data))
-		memset(root->data+root->size, 0, sizeof(root->data)-root->size);
+	nfs_copy_fh(root, (struct nfs_fh *) &data->root);
 
 	if (data->version != NFS_MOUNT_VERSION) {
 		printk("nfs warning: mount version %s than kernel\n",
@@ -1297,7 +1294,6 @@ static struct super_block *nfs_get_sb(struct file_system_type *fs_type,
 			data->bsize  = 0;
 		if (data->version < 4) {
 			data->flags &= ~NFS_MOUNT_VER3;
-			memset(root, 0, sizeof(*root));
 			root->size = NFS2_FHSIZE;
 			memcpy(root->data, data->old_root.data, NFS2_FHSIZE);
 		}

fs/nfs/mount_clnt.c

@@ -108,7 +108,6 @@ xdr_decode_fhstatus(struct rpc_rqst *req, u32 *p, struct mnt_fhstatus *res)
 {
 	struct nfs_fh *fh = res->fh;
 
-	memset((void *)fh, 0, sizeof(*fh));
 	if ((res->status = ntohl(*p++)) == 0) {
 		fh->size = NFS2_FHSIZE;
 		memcpy(fh->data, p, NFS2_FHSIZE);
@@ -121,7 +120,6 @@ xdr_decode_fhstatus3(struct rpc_rqst *req, u32 *p, struct mnt_fhstatus *res)
 {
 	struct nfs_fh *fh = res->fh;
 
-	memset((void *)fh, 0, sizeof(*fh));
 	if ((res->status = ntohl(*p++)) == 0) {
 		int size = ntohl(*p++);
 		if (size <= NFS3_FHSIZE) {

fs/nfs/nfs2xdr.c

@@ -77,8 +77,6 @@ xdr_encode_fhandle(u32 *p, struct nfs_fh *fhandle)
 static inline u32 *
 xdr_decode_fhandle(u32 *p, struct nfs_fh *fhandle)
 {
-	/* Zero handle first to allow comparisons */
-	memset(fhandle, 0, sizeof(*fhandle));
 	/* NFSv2 handles have a fixed length */
 	fhandle->size = NFS2_FHSIZE;
 	memcpy(fhandle->data, p, NFS2_FHSIZE);

fs/nfs/nfs3xdr.c

@@ -109,10 +109,6 @@ xdr_encode_fhandle(u32 *p, struct nfs_fh *fh)
 static inline u32 *
 xdr_decode_fhandle(u32 *p, struct nfs_fh *fh)
 {
-	/*
-	 * Zero all nonused bytes
-	 */
-	memset((u8 *)fh, 0, sizeof(*fh));
 	if ((fh->size = ntohl(*p++)) <= NFS3_FHSIZE) {
 		memcpy(fh->data, p, fh->size);
 		return p + XDR_QUADLEN(fh->size);

fs/nfs/nfsroot.c

@@ -495,10 +495,8 @@ static int __init root_nfs_get_handle(void)
 	if (status < 0)
 		printk(KERN_ERR "Root-NFS: Server returned error %d "
 				"while mounting %s\n", status, nfs_path);
-	else {
-		nfs_data.root.size = fh.size;
-		memcpy(nfs_data.root.data, fh.data, fh.size);
-	}
+	else
+		nfs_copy_fh(nfs_data.root, fh);
 
 	return status;
 }

include/linux/nfs.h

@@ -148,6 +148,12 @@ static inline int nfs_compare_fh(const struct nfs_fh *a, const struct nfs_fh *b)
 	return a->size != b->size || memcmp(a->data, b->data, a->size) != 0;
 }
 
+static inline void nfs_copy_fh(struct nfs_fh *target, const struct nfs_fh *source)
+{
+	target->size = source->size;
+	memcpy(target->data, source->data, source->size);
+}
+
 
 /*
  * This is really a general kernel constant, but since nothing like