NFS: Optimise away the previous cookie field

Replace the 'previous cookie' field in struct nfs_entry with the
array->last_cookie.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/dir.c

@@ -301,19 +301,20 @@ static int nfs_readdir_array_can_expand(struct nfs_cache_array *array)
 	return 0;
 }
 
-static
-int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
+static int nfs_readdir_page_array_append(struct page *page,
+					 const struct nfs_entry *entry,
+					 u64 *cookie)
 {
 	struct nfs_cache_array *array;
 	struct nfs_cache_array_entry *cache_entry;
 	const char *name;
-	int ret;
+	int ret = -ENOMEM;
 
 	name = nfs_readdir_copy_name(entry->name, entry->len);
-	if (!name)
-		return -ENOMEM;
 
 	array = kmap_atomic(page);
+	if (!name)
+		goto out;
 	ret = nfs_readdir_array_can_expand(array);
 	if (ret) {
 		kfree(name);
@@ -321,7 +322,7 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
 	}
 
 	cache_entry = &array->array[array->size];
-	cache_entry->cookie = entry->prev_cookie;
+	cache_entry->cookie = array->last_cookie;
 	cache_entry->ino = entry->ino;
 	cache_entry->d_type = entry->d_type;
 	cache_entry->name_len = entry->len;
@@ -333,6 +334,7 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
 	if (entry->eof != 0)
 		nfs_readdir_array_set_eof(array);
 out:
+	*cookie = array->last_cookie;
 	kunmap_atomic(array);
 	return ret;
 }
@@ -798,6 +800,7 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
 	struct xdr_stream stream;
 	struct xdr_buf buf;
 	struct page *scratch, *new, *page = *arrays;
+	u64 cookie;
 	int status;
 
 	scratch = alloc_page(GFP_KERNEL);
@@ -819,22 +822,21 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
 			nfs_prime_dcache(file_dentry(desc->file), entry,
 					desc->dir_verifier);
 
-		status = nfs_readdir_add_to_array(entry, page);
+		status = nfs_readdir_page_array_append(page, entry, &cookie);
 		if (status != -ENOSPC)
 			continue;
 
 		if (page->mapping != mapping) {
 			if (!--narrays)
 				break;
-			new = nfs_readdir_page_array_alloc(entry->prev_cookie,
-							   GFP_KERNEL);
+			new = nfs_readdir_page_array_alloc(cookie, GFP_KERNEL);
 			if (!new)
 				break;
 			arrays++;
 			*arrays = page = new;
 		} else {
-			new = nfs_readdir_page_get_next(
-				mapping, entry->prev_cookie, change_attr);
+			new = nfs_readdir_page_get_next(mapping, cookie,
+							change_attr);
 			if (!new)
 				break;
 			if (page != *arrays)
@@ -842,7 +844,7 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
 			page = new;
 		}
 		desc->page_index_max++;
-		status = nfs_readdir_add_to_array(entry, page);
+		status = nfs_readdir_page_array_append(page, entry, &cookie);
 	} while (!status && !entry->eof);
 
 	switch (status) {

fs/nfs/nfs2xdr.c

@@ -955,7 +955,6 @@ int nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
 	 * The type (size and byte order) of nfscookie isn't defined in
 	 * RFC 1094.  This implementation assumes that it's an XDR uint32.
 	 */
-	entry->prev_cookie = entry->cookie;
 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(!p))
 		return -EAGAIN;

fs/nfs/nfs3xdr.c

@@ -2024,7 +2024,6 @@ int nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
 			zero_nfs_fh3(entry->fh);
 	}
 
-	entry->prev_cookie = entry->cookie;
 	entry->cookie = new_cookie;
 
 	return 0;

fs/nfs/nfs4xdr.c

@@ -7508,7 +7508,6 @@ int nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
 	if (entry->fattr->valid & NFS_ATTR_FATTR_TYPE)
 		entry->d_type = nfs_umode_to_dtype(entry->fattr->mode);
 
-	entry->prev_cookie = entry->cookie;
 	entry->cookie = new_cookie;
 
 	return 0;

include/linux/nfs_xdr.h

@@ -745,8 +745,7 @@ struct nfs_auth_info {
  */
 struct nfs_entry {
 	__u64			ino;
-	__u64			cookie,
-				prev_cookie;
+	__u64			cookie;
 	const char *		name;
 	unsigned int		len;
 	int			eof;