Date: Sun, 18 Oct 2015 14:34:13 +0000 (UTC) From: Edward Tomasz Napierala <trasz@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r289511 - stable/10/sys/geom Message-ID: <201510181434.t9IEYDvd093387@repo.freebsd.org>
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Author: trasz Date: Sun Oct 18 14:34:13 2015 New Revision: 289511 URL: https://svnweb.freebsd.org/changeset/base/289511 Log: MFC r286237: Fix panic that would happen on forcibly unmounting devfs (note that as it is now, devfs ignores MNT_FORCE anyway, so it needs to be modified to trigger the panic) with consumers still opened. Note that this still results in a leak of r/w/e counters. It seems to be harmless, though. If anyone knows a better way to approach this - please tell. Sponsored by: The FreeBSD Foundation Modified: stable/10/sys/geom/geom_dev.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/geom/geom_dev.c ============================================================================== --- stable/10/sys/geom/geom_dev.c Sun Oct 18 14:31:54 2015 (r289510) +++ stable/10/sys/geom/geom_dev.c Sun Oct 18 14:34:13 2015 (r289511) @@ -399,6 +399,20 @@ g_dev_close(struct cdev *dev, int flags, #else e = 0; #endif + + /* + * The vgonel(9) - caused by eg. forced unmount of devfs - calls + * VOP_CLOSE(9) on devfs vnode without any FREAD or FWRITE flags, + * which would result in zero deltas, which in turn would cause + * panic in g_access(9). + * + * Note that we cannot zero the counters (ie. do "r = cp->acr" + * etc) instead, because the consumer might be opened in another + * devfs instance. + */ + if (r + w + e == 0) + return (EINVAL); + sc = cp->private; mtx_lock(&sc->sc_mtx); sc->sc_open += r + w + e;
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