From owner-svn-src-head@FreeBSD.ORG Tue Dec 6 11:24:04 2011 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5BB791065676; Tue, 6 Dec 2011 11:24:04 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 32ED28FC21; Tue, 6 Dec 2011 11:24:04 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id pB6BO4aG087536; Tue, 6 Dec 2011 11:24:04 GMT (envelope-from kib@svn.freebsd.org) Received: (from kib@localhost) by svn.freebsd.org (8.14.4/8.14.4/Submit) id pB6BO4Sc087534; Tue, 6 Dec 2011 11:24:04 GMT (envelope-from kib@svn.freebsd.org) Message-Id: <201112061124.pB6BO4Sc087534@svn.freebsd.org> From: Konstantin Belousov Date: Tue, 6 Dec 2011 11:24:04 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r228306 - head/sys/kern X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 Dec 2011 11:24:04 -0000 Author: kib Date: Tue Dec 6 11:24:03 2011 New Revision: 228306 URL: http://svn.freebsd.org/changeset/base/228306 Log: Most users of pipe(2) do not call fstat(2) on the returned pipe descriptors. Optimize for the case, by lazily allocating the pipe inode number at the fstat(2) time. If alloc_unr(9) returns failure, do not fail fstat(2), since uses of inode numbers are even rare then fstat(2), but provide zero inode forever. Note that alloc_unr() failure is unlikely due to total number of pipes in the system limited by the number of file descriptors. Based on the submission by: gianni MFC after: 2 weeks Modified: head/sys/kern/sys_pipe.c Modified: head/sys/kern/sys_pipe.c ============================================================================== --- head/sys/kern/sys_pipe.c Tue Dec 6 09:12:11 2011 (r228305) +++ head/sys/kern/sys_pipe.c Tue Dec 6 11:24:03 2011 (r228306) @@ -569,12 +569,7 @@ pipe_create(pipe, backing) /* If we're not backing this pipe, no need to do anything. */ error = 0; } - if (error == 0) { - pipe->pipe_ino = alloc_unr(pipeino_unr); - if (pipe->pipe_ino == -1) - /* pipeclose will clear allocated kva */ - error = ENOMEM; - } + pipe->pipe_ino = -1; return (error); } @@ -1398,16 +1393,40 @@ pipe_stat(fp, ub, active_cred, td) struct ucred *active_cred; struct thread *td; { - struct pipe *pipe = fp->f_data; + struct pipe *pipe; + int new_unr; #ifdef MAC int error; +#endif + pipe = fp->f_data; PIPE_LOCK(pipe); +#ifdef MAC error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); - PIPE_UNLOCK(pipe); - if (error) + if (error) { + PIPE_UNLOCK(pipe); return (error); + } #endif + /* + * Lazily allocate an inode number for the pipe. Most pipe + * users do not call fstat(2) on the pipe, which means that + * postponing the inode allocation until it is must be + * returned to userland is useful. If alloc_unr failed, + * assign st_ino zero instead of returning an error. + * Special pipe_ino values: + * -1 - not yet initialized; + * 0 - alloc_unr failed, return 0 as st_ino forever. + */ + if (pipe->pipe_ino == (ino_t)-1) { + new_unr = alloc_unr(pipeino_unr); + if (new_unr != -1) + pipe->pipe_ino = new_unr; + else + pipe->pipe_ino = 0; + } + PIPE_UNLOCK(pipe); + bzero(ub, sizeof(*ub)); ub->st_mode = S_IFIFO; ub->st_blksize = PAGE_SIZE;