Date: Thu, 13 Oct 2016 16:06:10 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: asomers@freebsd.org Cc: garga@freebsd.org, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r285050 - in head: lib/libutil usr.sbin/pwd_mkdb Message-ID: <201610132306.u9DN6Aod023917@gw.catspoiler.org> In-Reply-To: <CAOtMX2gnLugXB%2BBuuM%2Bsfs3DB%2BtAsA9NpkA-e0uerDXH2eKa0Q@mail.gmail.com>
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On 13 Oct, Alan Somers wrote: > On Thu, Jul 2, 2015 at 11:31 AM, Renato Botelho <garga@freebsd.org> wrote: >> Author: garga (ports committer) >> Date: Thu Jul 2 17:30:59 2015 >> New Revision: 285050 >> URL: https://svnweb.freebsd.org/changeset/base/285050 >> >> Log: >> When passwd or group information is changed (by pw, vipw, chpass, ...) >> temporary file is created and then a rename() call move it to official file. >> This operation didn't have any check to make sure data was written to disk >> and if a power cycle happens system could end up with a 0 length passwd >> or group database. >> >> There is a pfSense bug with more infor about it: >> >> https://redmine.pfsense.org/issues/4523 >> >> The following changes were made to protect passwd and group operations: >> >> * lib/libutil/gr_util.c: >> - Replace mkstemp() by mkostemp() with O_SYNC flag to create temp file >> - After rename(), fsync() call on directory for faster result >> >> * lib/libutil/pw_util.c >> - Replace mkstemp() by mkostemp() with O_SYNC flag to create temp file >> >> * usr.sbin/pwd_mkdb/pwd_mkdb.c >> - Added O_SYNC flag on dbopen() calls >> - After rename(), fsync() call on directory for faster result >> >> * lib/libutil/pw_util.3 >> - pw_lock() returns a file descriptor to master password file on success >> >> Differential Revision: https://reviews.freebsd.org/D2978 >> Approved by: bapt >> Sponsored by: Netgate >> >> Modified: >> head/lib/libutil/gr_util.c >> head/lib/libutil/pw_util.3 >> head/lib/libutil/pw_util.c >> head/usr.sbin/pwd_mkdb/pwd_mkdb.c > > This change is making certain pw operations very slow on ZFS root > systems. The problem is that when you open a file with O_SYNC, every > single write(2) call turns into a zil_commit on ZFS, which is fairly > expensive. Did you consider using fsync(2) on the temporary files > instead of opening them with O_SYNC? I just tried that now, and I see > a considerable speedup when running the tests in > /usr/tests/usr.sbin/pw: > > Using O_SYNC, as CURRENT does: 4 minutes 5.2 seconds > No synchronous operations at all: 49.5 seconds > Using fsync(2): 56.0 seconds pwd_mkdb was fixed back in February with by switching to fsync() in r295925. It looks like libutil was not fixed, though.help
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