Date: Tue, 18 Dec 2012 04:38:35 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r244376 - in stable/9/sys: kern sys Message-ID: <201212180438.qBI4cZwJ054963@svn.freebsd.org>
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Author: kib Date: Tue Dec 18 04:38:34 2012 New Revision: 244376 URL: http://svnweb.freebsd.org/changeset/base/244376 Log: MFC r243835: The vnode_free_list_mtx is required unconditionally when iterating over the active list. MFC r244095: Do not yield while owning a mutex, by stopping acquiring mount interlock. MFC r244240: Use user priority for the yield, do not spin on UP. Restructure the iteration initializer and the iterator to remove code duplication. Modified: stable/9/sys/kern/vfs_subr.c stable/9/sys/sys/mount.h Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/kern/vfs_subr.c ============================================================================== --- stable/9/sys/kern/vfs_subr.c Tue Dec 18 04:27:33 2012 (r244375) +++ stable/9/sys/kern/vfs_subr.c Tue Dec 18 04:38:34 2012 (r244376) @@ -69,6 +69,7 @@ __FBSDID("$FreeBSD$"); #include <sys/reboot.h> #include <sys/sched.h> #include <sys/sleepqueue.h> +#include <sys/smp.h> #include <sys/stat.h> #include <sys/sysctl.h> #include <sys/syslog.h> @@ -4697,20 +4698,54 @@ __mnt_vnode_markerfree_all(struct vnode * These are helper functions for filesystems to traverse their * active vnodes. See MNT_VNODE_FOREACH_ACTIVE() in sys/mount.h */ -struct vnode * -__mnt_vnode_next_active(struct vnode **mvp, struct mount *mp) +static void +mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *mp) { - struct vnode *vp, *nvp; - if (should_yield()) - kern_yield(PRI_UNCHANGED); + KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch")); + MNT_ILOCK(mp); + MNT_REL(mp); + MNT_IUNLOCK(mp); + free(*mvp, M_VNODE_MARKER); + *mvp = NULL; +} + +#ifdef SMP +#define ALWAYS_YIELD (mp_ncpus == 1) +#else +#define ALWAYS_YIELD 1 +#endif + +static struct vnode * +mnt_vnode_next_active(struct vnode **mvp, struct mount *mp) +{ + struct vnode *vp, *nvp; + + mtx_assert(&vnode_free_list_mtx, MA_OWNED); KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch")); +restart: vp = TAILQ_NEXT(*mvp, v_actfreelist); + TAILQ_REMOVE(&mp->mnt_activevnodelist, *mvp, v_actfreelist); while (vp != NULL) { - VI_LOCK(vp); - if (vp->v_mount == mp && vp->v_type != VMARKER && - (vp->v_iflag & VI_DOOMED) == 0) + if (vp->v_type == VMARKER) { + vp = TAILQ_NEXT(vp, v_actfreelist); + continue; + } + if (!VI_TRYLOCK(vp)) { + if (ALWAYS_YIELD || should_yield()) { + TAILQ_INSERT_BEFORE(vp, *mvp, v_actfreelist); + mtx_unlock(&vnode_free_list_mtx); + kern_yield(PRI_USER); + mtx_lock(&vnode_free_list_mtx); + goto restart; + } + continue; + } + KASSERT(vp->v_type != VMARKER, ("locked marker %p", vp)); + KASSERT(vp->v_mount == mp || vp->v_mount == NULL, + ("alien vnode on the active list %p %p", vp, mp)); + if (vp->v_mount == mp && (vp->v_iflag & VI_DOOMED) == 0) break; nvp = TAILQ_NEXT(vp, v_actfreelist); VI_UNLOCK(vp); @@ -4719,73 +4754,60 @@ __mnt_vnode_next_active(struct vnode **m /* Check if we are done */ if (vp == NULL) { - __mnt_vnode_markerfree_active(mvp, mp); - /* MNT_IUNLOCK(mp); -- done in above function */ - mtx_assert(MNT_MTX(mp), MA_NOTOWNED); + mtx_unlock(&vnode_free_list_mtx); + mnt_vnode_markerfree_active(mvp, mp); return (NULL); } - mtx_lock(&vnode_free_list_mtx); - TAILQ_REMOVE(&mp->mnt_activevnodelist, *mvp, v_actfreelist); TAILQ_INSERT_AFTER(&mp->mnt_activevnodelist, vp, *mvp, v_actfreelist); mtx_unlock(&vnode_free_list_mtx); - MNT_IUNLOCK(mp); + ASSERT_VI_LOCKED(vp, "active iter"); + KASSERT((vp->v_iflag & VI_ACTIVE) != 0, ("Non-active vp %p", vp)); return (vp); } +#undef ALWAYS_YIELD + +struct vnode * +__mnt_vnode_next_active(struct vnode **mvp, struct mount *mp) +{ + + if (should_yield()) + kern_yield(PRI_UNCHANGED); + mtx_lock(&vnode_free_list_mtx); + return (mnt_vnode_next_active(mvp, mp)); +} struct vnode * __mnt_vnode_first_active(struct vnode **mvp, struct mount *mp) { - struct vnode *vp, *nvp; + struct vnode *vp; *mvp = malloc(sizeof(struct vnode), M_VNODE_MARKER, M_WAITOK | M_ZERO); MNT_ILOCK(mp); MNT_REF(mp); + MNT_IUNLOCK(mp); (*mvp)->v_type = VMARKER; + (*mvp)->v_mount = mp; + mtx_lock(&vnode_free_list_mtx); vp = TAILQ_FIRST(&mp->mnt_activevnodelist); - while (vp != NULL) { - VI_LOCK(vp); - if (vp->v_mount == mp && vp->v_type != VMARKER && - (vp->v_iflag & VI_DOOMED) == 0) - break; - nvp = TAILQ_NEXT(vp, v_actfreelist); - VI_UNLOCK(vp); - vp = nvp; - } - - /* Check if we are done */ if (vp == NULL) { - MNT_REL(mp); - MNT_IUNLOCK(mp); - free(*mvp, M_VNODE_MARKER); - *mvp = NULL; + mtx_unlock(&vnode_free_list_mtx); + mnt_vnode_markerfree_active(mvp, mp); return (NULL); } - (*mvp)->v_mount = mp; - mtx_lock(&vnode_free_list_mtx); - TAILQ_INSERT_AFTER(&mp->mnt_activevnodelist, vp, *mvp, v_actfreelist); - mtx_unlock(&vnode_free_list_mtx); - MNT_IUNLOCK(mp); - return (vp); + TAILQ_INSERT_BEFORE(vp, *mvp, v_actfreelist); + return (mnt_vnode_next_active(mvp, mp)); } void __mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *mp) { - if (*mvp == NULL) { - MNT_IUNLOCK(mp); + if (*mvp == NULL) return; - } - - mtx_assert(MNT_MTX(mp), MA_OWNED); - KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch")); mtx_lock(&vnode_free_list_mtx); TAILQ_REMOVE(&mp->mnt_activevnodelist, *mvp, v_actfreelist); mtx_unlock(&vnode_free_list_mtx); - MNT_REL(mp); - MNT_IUNLOCK(mp); - free(*mvp, M_VNODE_MARKER); - *mvp = NULL; + mnt_vnode_markerfree_active(mvp, mp); } Modified: stable/9/sys/sys/mount.h ============================================================================== --- stable/9/sys/sys/mount.h Tue Dec 18 04:27:33 2012 (r244375) +++ stable/9/sys/sys/mount.h Tue Dec 18 04:38:34 2012 (r244376) @@ -217,17 +217,12 @@ struct vnode *__mnt_vnode_next_active(st struct vnode *__mnt_vnode_first_active(struct vnode **mvp, struct mount *mp); void __mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *); -#define MNT_VNODE_FOREACH_ACTIVE(vp, mp, mvp) \ - for (vp = __mnt_vnode_first_active(&(mvp), (mp)); \ +#define MNT_VNODE_FOREACH_ACTIVE(vp, mp, mvp) \ + for (vp = __mnt_vnode_first_active(&(mvp), (mp)); \ (vp) != NULL; vp = __mnt_vnode_next_active(&(mvp), (mp))) #define MNT_VNODE_FOREACH_ACTIVE_ABORT(mp, mvp) \ - do { \ - MNT_ILOCK(mp); \ - __mnt_vnode_markerfree_active(&(mvp), (mp)); \ - /* MNT_IUNLOCK(mp); -- done in above function */ \ - mtx_assert(MNT_MTX(mp), MA_NOTOWNED); \ - } while (0) + __mnt_vnode_markerfree_active(&(mvp), (mp)) /* * Definitions for MNT_VNODE_FOREACH.
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