From owner-svn-src-head@freebsd.org Thu Aug 27 22:14:59 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 7EE033C5480; Thu, 27 Aug 2020 22:14:59 +0000 (UTC) (envelope-from mckusick@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4BcxqR2m7Sz4ryS; Thu, 27 Aug 2020 22:14:59 +0000 (UTC) (envelope-from mckusick@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 3DDABB201; Thu, 27 Aug 2020 22:14:59 +0000 (UTC) (envelope-from mckusick@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 07RMExgt080415; Thu, 27 Aug 2020 22:14:59 GMT (envelope-from mckusick@FreeBSD.org) Received: (from mckusick@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 07RMExfE080414; Thu, 27 Aug 2020 22:14:59 GMT (envelope-from mckusick@FreeBSD.org) Message-Id: <202008272214.07RMExfE080414@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mckusick set sender to mckusick@FreeBSD.org using -f From: Kirk McKusick Date: Thu, 27 Aug 2020 22:14:59 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r364895 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mckusick X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 364895 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 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: Thu, 27 Aug 2020 22:14:59 -0000 Author: mckusick Date: Thu Aug 27 22:14:58 2020 New Revision: 364895 URL: https://svnweb.freebsd.org/changeset/base/364895 Log: Add a comment to clarify when and why cached names are deleted during pathname lookup. Reviewed by: kib MFC after: 3 days Sponsored by: Netflix Modified: head/sys/kern/vfs_lookup.c Modified: head/sys/kern/vfs_lookup.c ============================================================================== --- head/sys/kern/vfs_lookup.c Thu Aug 27 21:47:43 2020 (r364894) +++ head/sys/kern/vfs_lookup.c Thu Aug 27 22:14:58 2020 (r364895) @@ -785,6 +785,16 @@ lookup(struct nameidata *ndp) wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); + /* + * When set to zero, docache causes the last component of the + * pathname to be deleted from the cache and the full lookup + * of the name to be done (via VOP_CACHEDLOOKUP()). Often + * filesystems need some pre-computed values that are made + * during the full lookup, for instance UFS sets dp->i_offset. + * + * The docache variable is set to zero when requested by the + * NOCACHE flag and for all modifying operations except CREATE. + */ docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; if (cnp->cn_nameiop == DELETE || (wantparent && cnp->cn_nameiop != CREATE &&