From owner-svn-src-head@FreeBSD.ORG Tue Nov 19 18:43:48 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 29A4B979; Tue, 19 Nov 2013 18:43:48 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id F30342380; Tue, 19 Nov 2013 18:43:47 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.7/8.14.7) with ESMTP id rAJIhlZU026955; Tue, 19 Nov 2013 18:43:47 GMT (envelope-from avg@svn.freebsd.org) Received: (from avg@localhost) by svn.freebsd.org (8.14.7/8.14.5/Submit) id rAJIhlSF026954; Tue, 19 Nov 2013 18:43:47 GMT (envelope-from avg@svn.freebsd.org) Message-Id: <201311191843.rAJIhlSF026954@svn.freebsd.org> From: Andriy Gapon Date: Tue, 19 Nov 2013 18:43:47 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r258353 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs X-SVN-Group: head 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: 2.1.16 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, 19 Nov 2013 18:43:48 -0000 Author: avg Date: Tue Nov 19 18:43:47 2013 New Revision: 258353 URL: http://svnweb.freebsd.org/changeset/base/258353 Log: zfs page_busy: fix the boundaries of the cleared range This is a fix for a regression introduced in r246293. vm_page_clear_dirty expects the range to have DEV_BSIZE aligned boundaries, otherwise it extends them. Thus it can happen that the whole page is marked clean while actually having some small dirty region(s). This commit makes the range properly aligned and ensures that only the clean data is marked as such. It would interesting to evaluate how much benefit clearing with DEV_BSIZE granularity produces. Perhaps instead we should clear the whole page when it is completely overwritten and don't bother clearing any bits if only a portion a page is written. Reported by: George Hartzell , Richard Todd Tested by: George Hartzell , Reviewed by: kib MFC after: 5 days Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Tue Nov 19 18:35:38 2013 (r258352) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Tue Nov 19 18:43:47 2013 (r258353) @@ -329,6 +329,20 @@ page_busy(vnode_t *vp, int64_t start, in { vm_object_t obj; vm_page_t pp; + int64_t end; + + /* + * At present vm_page_clear_dirty extends the cleared range to DEV_BSIZE + * aligned boundaries, if the range is not aligned. As a result a + * DEV_BSIZE subrange with partially dirty data may get marked as clean. + * It may happen that all DEV_BSIZE subranges are marked clean and thus + * the whole page would be considred clean despite have some dirty data. + * For this reason we should shrink the range to DEV_BSIZE aligned + * boundaries before calling vm_page_clear_dirty. + */ + end = rounddown2(off + nbytes, DEV_BSIZE); + off = roundup2(off, DEV_BSIZE); + nbytes = end - off; obj = vp->v_object; zfs_vmobject_assert_wlocked(obj); @@ -363,7 +377,8 @@ page_busy(vnode_t *vp, int64_t start, in ASSERT3U(pp->valid, ==, VM_PAGE_BITS_ALL); vm_object_pip_add(obj, 1); pmap_remove_write(pp); - vm_page_clear_dirty(pp, off, nbytes); + if (nbytes != 0) + vm_page_clear_dirty(pp, off, nbytes); } break; }