ceph: preallocate buffer for readdir reply

Preallocate buffer for readdir reply. Limit number of entries in
readdir reply according to the buffer size.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

fs/ceph/dir.c

@@ -252,8 +252,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 	int err;
 	u32 ftype;
 	struct ceph_mds_reply_info_parsed *rinfo;
-	const int max_entries = fsc->mount_options->max_readdir;
-	const int max_bytes = fsc->mount_options->max_readdir_bytes;
 
 	dout("readdir %p file %p frag %u off %u\n", inode, file, frag, off);
 	if (fi->flags & CEPH_F_ATEND)
@@ -327,6 +325,11 @@ more:
 		req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
 		if (IS_ERR(req))
 			return PTR_ERR(req);
+		err = ceph_alloc_readdir_reply_buffer(req, inode);
+		if (err) {
+			ceph_mdsc_put_request(req);
+			return err;
+		}
 		req->r_inode = inode;
 		ihold(inode);
 		req->r_dentry = dget(file->f_dentry);
@@ -337,9 +340,6 @@ more:
 		req->r_path2 = kstrdup(fi->last_name, GFP_NOFS);
 		req->r_readdir_offset = fi->next_offset;
 		req->r_args.readdir.frag = cpu_to_le32(frag);
-		req->r_args.readdir.max_entries = cpu_to_le32(max_entries);
-		req->r_args.readdir.max_bytes = cpu_to_le32(max_bytes);
-		req->r_num_caps = max_entries + 1;
 		err = ceph_mdsc_do_request(mdsc, NULL, req);
 		if (err < 0) {
 			ceph_mdsc_put_request(req);