From 9cf4c952caa443733ad3b44fa274a2018a94f5f5 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Thu, 3 Jan 2013 19:17:57 +0000 Subject: [PATCH] Add the "nocache" nullfs mount option, which disables the caching of the free nullfs vnodes, switching nullfs behaviour to pre-r240285. The option is mostly intended as the last-resort when higher pressure on the vnode cache due to doubling of the vnode counts is not desirable. Note that disabling the cache costs more than 2x wall time in the metadata-hungry scenarious. The default is "cache". Tested and benchmarked by: pho (previous version) MFC after: 2 weeks --- sys/fs/nullfs/null.h | 8 ++++++ sys/fs/nullfs/null_subr.c | 3 +++ sys/fs/nullfs/null_vfsops.c | 50 +++++++++++++++++++++++++++---------- sys/fs/nullfs/null_vnops.c | 15 +++++++++++ 4 files changed, 63 insertions(+), 13 deletions(-) diff --git a/sys/fs/nullfs/null.h b/sys/fs/nullfs/null.h index 0878e559329..4f37020d6da 100644 --- a/sys/fs/nullfs/null.h +++ b/sys/fs/nullfs/null.h @@ -34,9 +34,15 @@ * $FreeBSD$ */ +#ifndef FS_NULL_H +#define FS_NULL_H + +#define NULLM_CACHE 0x0001 + struct null_mount { struct mount *nullm_vfs; struct vnode *nullm_rootvp; /* Reference to root null_node */ + uint64_t nullm_flags; }; #ifdef _KERNEL @@ -80,3 +86,5 @@ MALLOC_DECLARE(M_NULLFSNODE); #endif /* NULLFS_DEBUG */ #endif /* _KERNEL */ + +#endif diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c index b2c7a75d14e..f82d7380747 100644 --- a/sys/fs/nullfs/null_subr.c +++ b/sys/fs/nullfs/null_subr.c @@ -224,6 +224,9 @@ null_nodeget(mp, lowervp, vpp) * provide ready to use vnode. */ if (VOP_ISLOCKED(lowervp) != LK_EXCLUSIVE) { + KASSERT((MOUNTTONULLMOUNT(mp)->nullm_flags & NULLM_CACHE) == 0, + ("lowervp %p is not excl locked and cache is disabled", + lowervp)); vn_lock(lowervp, LK_UPGRADE | LK_RETRY); if ((lowervp->v_iflag & VI_DOOMED) != 0) { vput(lowervp); diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c index 7d84d519066..5abfa49cf14 100644 --- a/sys/fs/nullfs/null_vfsops.c +++ b/sys/fs/nullfs/null_vfsops.c @@ -67,6 +67,15 @@ static vfs_vget_t nullfs_vget; static vfs_extattrctl_t nullfs_extattrctl; static vfs_reclaim_lowervp_t nullfs_reclaim_lowervp; +/* Mount options that we support. */ +static const char *nullfs_opts[] = { + "cache", + "export", + "from", + "target", + NULL +}; + /* * Mount null layer */ @@ -86,9 +95,11 @@ nullfs_mount(struct mount *mp) if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS)) return (EPERM); - if (mp->mnt_flag & MNT_ROOTFS) return (EOPNOTSUPP); + if (vfs_filteropt(mp->mnt_optnew, nullfs_opts)) + return (EINVAL); + /* * Update is a no-op */ @@ -149,7 +160,7 @@ nullfs_mount(struct mount *mp) } xmp = (struct null_mount *) malloc(sizeof(struct null_mount), - M_NULLFSMNT, M_WAITOK); + M_NULLFSMNT, M_WAITOK | M_ZERO); /* * Save reference to underlying FS @@ -187,16 +198,27 @@ nullfs_mount(struct mount *mp) mp->mnt_flag |= MNT_LOCAL; MNT_IUNLOCK(mp); } + + xmp->nullm_flags |= NULLM_CACHE; + if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0) + xmp->nullm_flags &= ~NULLM_CACHE; + MNT_ILOCK(mp); - mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & - (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED); + if ((xmp->nullm_flags & NULLM_CACHE) != 0) { + mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & + (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | + MNTK_EXTENDED_SHARED); + } mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT; MNT_IUNLOCK(mp); mp->mnt_data = xmp; vfs_getnewfsid(mp); - MNT_ILOCK(xmp->nullm_vfs); - TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, mnt_upper_link); - MNT_IUNLOCK(xmp->nullm_vfs); + if ((xmp->nullm_flags & NULLM_CACHE) != 0) { + MNT_ILOCK(xmp->nullm_vfs); + TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, + mnt_upper_link); + MNT_IUNLOCK(xmp->nullm_vfs); + } vfs_mountedfrom(mp, target); @@ -234,13 +256,15 @@ nullfs_unmount(mp, mntflags) */ mntdata = mp->mnt_data; ump = mntdata->nullm_vfs; - MNT_ILOCK(ump); - while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { - ump->mnt_kern_flag |= MNTK_VGONE_WAITER; - msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); + if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { + MNT_ILOCK(ump); + while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { + ump->mnt_kern_flag |= MNTK_VGONE_WAITER; + msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); + } + TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); + MNT_IUNLOCK(ump); } - TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); - MNT_IUNLOCK(ump); mp->mnt_data = NULL; free(mntdata, M_NULLFSMNT); return (0); diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c index f530ed217f2..cc35d819149 100644 --- a/sys/fs/nullfs/null_vnops.c +++ b/sys/fs/nullfs/null_vnops.c @@ -692,7 +692,22 @@ null_unlock(struct vop_unlock_args *ap) static int null_inactive(struct vop_inactive_args *ap __unused) { + struct vnode *vp; + struct mount *mp; + struct null_mount *xmp; + vp = ap->a_vp; + mp = vp->v_mount; + xmp = MOUNTTONULLMOUNT(mp); + if ((xmp->nullm_flags & NULLM_CACHE) == 0) { + /* + * If this is the last reference and caching of the + * nullfs vnodes is not enabled, then free up the + * vnode so as not to tie up the lower vnodes. + */ + vp->v_object = NULL; + vrecycle(vp); + } return (0); }