Date: Thu, 30 Jan 2020 19:34:37 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r357306 - head/sys/fs/nullfs Message-ID: <202001301934.00UJYb2v091902@repo.freebsd.org>
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Author: kib Date: Thu Jan 30 19:34:37 2020 New Revision: 357306 URL: https://svnweb.freebsd.org/changeset/base/357306 Log: Fix a bug in r357199. Around a generic call to null_nodeget(), there is nothing that would prevent the unmount of the nullfs mp until we process to the insmntque1() point. Calculate the VV_ROOT flag after insmntque1() to not access mp->mnt_data before we have an exclusively locked vnode from this mount point on the mp vnode list. Reported and tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/fs/nullfs/null_subr.c Modified: head/sys/fs/nullfs/null_subr.c ============================================================================== --- head/sys/fs/nullfs/null_subr.c Thu Jan 30 19:15:27 2020 (r357305) +++ head/sys/fs/nullfs/null_subr.c Thu Jan 30 19:34:37 2020 (r357306) @@ -252,11 +252,12 @@ null_nodeget(mp, lowervp, vpp) vp->v_type = lowervp->v_type; vp->v_data = xp; vp->v_vnlock = lowervp->v_vnlock; - if (lowervp == MOUNTTONULLMOUNT(mp)->nullm_lowerrootvp) - vp->v_vflag |= VV_ROOT; error = insmntque1(vp, mp, null_insmntque_dtr, xp); if (error != 0) return (error); + if (lowervp == MOUNTTONULLMOUNT(mp)->nullm_lowerrootvp) + vp->v_vflag |= VV_ROOT; + /* * Atomically insert our new node into the hash or vget existing * if someone else has beaten us to it.
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