Date: Sun, 12 Apr 2009 19:41:16 +0000 (UTC) From: Alexander Kabaev <kan@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org Subject: svn commit: r190973 - in stable/7/sys: . contrib/pf dev/ath/ath_hal dev/cxgb kern sys Message-ID: <200904121941.n3CJfGHV036939@svn.freebsd.org>
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Author: kan Date: Sun Apr 12 19:41:16 2009 New Revision: 190973 URL: http://svn.freebsd.org/changeset/base/190973 Log: MFC changes 190533 and 190945: Replace v_dd vnode pointer with v_cache_dd pointer to struct namecache in directory vnodes. Allow namecache dotdot entry to be created pointing from child vnode to parent vnode if no existing links in opposite direction exist. Use direct link from parent to child for dotdot lookups otherwise. This restores more efficient dotdot caching in NFS filesystems which was lost when vnodes stoppped being type stable. Majority of backporting work for this was done by jhb. Reviewed by: jhb, kib Approved by: re (kib) Modified: stable/7/sys/ (props changed) stable/7/sys/contrib/pf/ (props changed) stable/7/sys/dev/ath/ath_hal/ (props changed) stable/7/sys/dev/cxgb/ (props changed) stable/7/sys/kern/vfs_cache.c stable/7/sys/kern/vfs_subr.c stable/7/sys/sys/vnode.h Modified: stable/7/sys/kern/vfs_cache.c ============================================================================== --- stable/7/sys/kern/vfs_cache.c Sun Apr 12 19:06:41 2009 (r190972) +++ stable/7/sys/kern/vfs_cache.c Sun Apr 12 19:41:16 2009 (r190973) @@ -182,7 +182,8 @@ static MALLOC_DEFINE(M_VFSCACHE, "vfscac /* * Flags in namecache.nc_flag */ -#define NCF_WHITE 1 +#define NCF_WHITE 0x01 +#define NCF_ISDOTDOT 0x02 #ifdef DIAGNOSTIC /* @@ -283,14 +284,20 @@ cache_zap(ncp) CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); vp = NULL; LIST_REMOVE(ncp, nc_hash); - LIST_REMOVE(ncp, nc_src); - if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { - vp = ncp->nc_dvp; - numcachehv--; + if (ncp->nc_flag & NCF_ISDOTDOT) { + if (ncp == ncp->nc_dvp->v_cache_dd) + ncp->nc_dvp->v_cache_dd = NULL; + } else { + LIST_REMOVE(ncp, nc_src); + if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { + vp = ncp->nc_dvp; + numcachehv--; + } } if (ncp->nc_vp) { TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); - ncp->nc_vp->v_dd = NULL; + if (ncp == ncp->nc_vp->v_cache_dd) + ncp->nc_vp->v_cache_dd = NULL; } else { TAILQ_REMOVE(&ncneg, ncp, nc_dst); numneg--; @@ -348,12 +355,21 @@ retry: } if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { dotdothits++; - if (dvp->v_dd == NULL || - (cnp->cn_flags & MAKEENTRY) == 0) { + if (dvp->v_cache_dd == NULL) { CACHE_UNLOCK(); return (0); } - *vpp = dvp->v_dd; + if ((cnp->cn_flags & MAKEENTRY) == 0) { + if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) + cache_zap(dvp->v_cache_dd); + dvp->v_cache_dd = NULL; + CACHE_UNLOCK(); + return (0); + } + if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) + *vpp = dvp->v_cache_dd->nc_vp; + else + *vpp = dvp->v_cache_dd->nc_dvp; CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", dvp, cnp->cn_nameptr, *vpp); goto success; @@ -484,6 +500,7 @@ cache_enter(dvp, vp, cnp) struct namecache *ncp, *n2; struct nchashhead *ncpp; u_int32_t hash; + int flag; int hold; int zap; int len; @@ -501,23 +518,33 @@ cache_enter(dvp, vp, cnp) if (numcache >= desiredvnodes * 2) return; + flag = 0; if (cnp->cn_nameptr[0] == '.') { - if (cnp->cn_namelen == 1) { + if (cnp->cn_namelen == 1) return; - } - /* - * For dotdot lookups only cache the v_dd pointer if the - * directory has a link back to its parent via v_cache_dst. - * Without this an unlinked directory would keep a soft - * reference to its parent which could not be NULLd at - * cache_purge() time. - */ if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { CACHE_LOCK(); - if (!TAILQ_EMPTY(&dvp->v_cache_dst)) - dvp->v_dd = vp; + /* + * If dotdot entry already exists, just retarget it + * to new parent vnode, otherwise continue with new + * namecache entry allocation. + */ + if ((ncp = dvp->v_cache_dd) != NULL) { + if (ncp->nc_flag & NCF_ISDOTDOT) { + KASSERT(ncp->nc_dvp == dvp, + ("wrong isdotdot parent")); + TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, + ncp, nc_dst); + TAILQ_INSERT_HEAD(&vp->v_cache_dst, + ncp, nc_dst); + ncp->nc_vp = vp; + CACHE_UNLOCK(); + return; + } + } + dvp->v_cache_dd = NULL; CACHE_UNLOCK(); - return; + flag = NCF_ISDOTDOT; } } @@ -531,6 +558,7 @@ cache_enter(dvp, vp, cnp) ncp = cache_alloc(cnp->cn_namelen); ncp->nc_vp = vp; ncp->nc_dvp = dvp; + ncp->nc_flag = flag; len = ncp->nc_nlen = cnp->cn_namelen; hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); bcopy(cnp->cn_nameptr, ncp->nc_name, len); @@ -553,14 +581,35 @@ cache_enter(dvp, vp, cnp) } } + if (flag == NCF_ISDOTDOT) { + /* + * See if we are trying to add .. entry, but some other lookup + * has populated v_cache_dd pointer already. + */ + if (dvp->v_cache_dd != NULL) { + CACHE_UNLOCK(); + cache_free(ncp); + return; + } + KASSERT(vp == NULL || vp->v_type == VDIR, + ("wrong vnode type %p", vp)); + dvp->v_cache_dd = ncp; + } + numcache++; if (!vp) { numneg++; - ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0; + if (cnp->cn_flags & ISWHITEOUT) + ncp->nc_flag |= NCF_WHITE; } else if (vp->v_type == VDIR) { - vp->v_dd = dvp; + if (flag != NCF_ISDOTDOT) { + if ((n2 = vp->v_cache_dd) != NULL && + (n2->nc_flag & NCF_ISDOTDOT) != 0) + cache_zap(n2); + vp->v_cache_dd = ncp; + } } else { - vp->v_dd = NULL; + vp->v_cache_dd = NULL; } /* @@ -568,11 +617,14 @@ cache_enter(dvp, vp, cnp) * within the cache entries table. */ LIST_INSERT_HEAD(ncpp, ncp, nc_hash); - if (LIST_EMPTY(&dvp->v_cache_src)) { - hold = 1; - numcachehv++; + if (flag != NCF_ISDOTDOT) { + if (LIST_EMPTY(&dvp->v_cache_src)) { + hold = 1; + numcachehv++; + } + LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); } - LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); + /* * If the entry is "negative", we place it into the * "negative" cache queue, otherwise, we place it into the @@ -627,7 +679,12 @@ cache_purge(vp) cache_zap(LIST_FIRST(&vp->v_cache_src)); while (!TAILQ_EMPTY(&vp->v_cache_dst)) cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); - vp->v_dd = NULL; + if (vp->v_cache_dd != NULL) { + KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, + ("lost dotdot link")); + cache_zap(vp->v_cache_dd); + } + KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); CACHE_UNLOCK(); } @@ -877,18 +934,19 @@ vn_fullpath1(struct thread *td, struct v vp = vp->v_mount->mnt_vnodecovered; continue; } - if (vp->v_dd == NULL) { + if (vp->v_type != VDIR) { numfullpathfail1++; error = ENOTDIR; break; } - ncp = TAILQ_FIRST(&vp->v_cache_dst); + TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) + if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) + break; if (!ncp) { numfullpathfail2++; error = ENOENT; break; } - MPASS(ncp->nc_dvp == vp->v_dd); for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--) *--bp = ncp->nc_name[i]; if (bp == buf) { Modified: stable/7/sys/kern/vfs_subr.c ============================================================================== --- stable/7/sys/kern/vfs_subr.c Sun Apr 12 19:06:41 2009 (r190972) +++ stable/7/sys/kern/vfs_subr.c Sun Apr 12 19:41:16 2009 (r190973) @@ -800,6 +800,7 @@ vdestroy(struct vnode *vp) VNASSERT(bo->bo_dirty.bv_root == NULL, vp, ("dirtyblkroot not NULL")); VNASSERT(TAILQ_EMPTY(&vp->v_cache_dst), vp, ("vp has namecache dst")); VNASSERT(LIST_EMPTY(&vp->v_cache_src), vp, ("vp has namecache src")); + VNASSERT(vp->v_cache_dd == NULL, vp, ("vp has namecache for ..")); VI_UNLOCK(vp); #ifdef MAC mac_destroy_vnode(vp); Modified: stable/7/sys/sys/vnode.h ============================================================================== --- stable/7/sys/sys/vnode.h Sun Apr 12 19:06:41 2009 (r190972) +++ stable/7/sys/sys/vnode.h Sun Apr 12 19:41:16 2009 (r190973) @@ -138,7 +138,7 @@ struct vnode { */ LIST_HEAD(, namecache) v_cache_src; /* c Cache entries from us */ TAILQ_HEAD(, namecache) v_cache_dst; /* c Cache entries to us */ - struct vnode *v_dd; /* c .. vnode */ + struct namecache *v_cache_dd; /* c Cache entry for .. vnode */ /* * clustering stuff
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