From 654e644e80ca24a067c93f09c8276b3647acdb21 Mon Sep 17 00:00:00 2001 From: Mateusz Guzik Date: Tue, 14 Jul 2020 21:16:48 +0000 Subject: [PATCH] cache: remove neg_locked argument from cache_zap_locked Tested by: pho --- sys/kern/vfs_cache.c | 59 +++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 28 deletions(-) diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c index 20e02ef473b4..b3444a016809 100644 --- a/sys/kern/vfs_cache.c +++ b/sys/kern/vfs_cache.c @@ -441,7 +441,7 @@ STATNODE_COUNTER(numneg_evicted, STATNODE_COUNTER(shrinking_skipped, "Number of times shrinking was already in progress"); -static void cache_zap_locked(struct namecache *ncp, bool neg_locked); +static void cache_zap_locked(struct namecache *ncp); static int vn_fullpath_hardlink(struct thread *td, struct nameidata *ndp, char **retbuf, char **freebuf, size_t *buflen); static int vn_fullpath_any(struct thread *td, struct vnode *vp, struct vnode *rdir, @@ -778,7 +778,7 @@ cache_negative_insert(struct namecache *ncp) } static void -cache_negative_remove(struct namecache *ncp, bool neg_locked) +cache_negative_remove(struct namecache *ncp) { struct neglist *neglist; struct negstate *negstate; @@ -788,18 +788,16 @@ cache_negative_remove(struct namecache *ncp, bool neg_locked) cache_assert_bucket_locked(ncp, RA_WLOCKED); neglist = NCP2NEGLIST(ncp); negstate = NCP2NEGSTATE(ncp); - if (!neg_locked) { - if ((negstate->neg_flag & NEG_HOT) != 0) { - hot_locked = true; - mtx_lock(&ncneg_hot.nl_lock); - if ((negstate->neg_flag & NEG_HOT) == 0) { - list_locked = true; - mtx_lock(&neglist->nl_lock); - } - } else { + if ((negstate->neg_flag & NEG_HOT) != 0) { + hot_locked = true; + mtx_lock(&ncneg_hot.nl_lock); + if ((negstate->neg_flag & NEG_HOT) == 0) { list_locked = true; mtx_lock(&neglist->nl_lock); } + } else { + list_locked = true; + mtx_lock(&neglist->nl_lock); } if ((negstate->neg_flag & NEG_HOT) != 0) { mtx_assert(&ncneg_hot.nl_lock, MA_OWNED); @@ -888,19 +886,24 @@ cache_negative_zap_one(void) mtx_unlock(&neglist->nl_lock); mtx_lock(dvlp); rw_wlock(blp); - mtx_lock(&neglist->nl_lock); + /* + * Enter SMR to safely check the negative list. + * Even if the found pointer matches, the entry may now be reallocated + * and used by a different vnode. + */ + vfs_smr_enter(); ncp2 = TAILQ_FIRST(&neglist->nl_list); if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) || - blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) { + blp != NCP2BUCKETLOCK(ncp2)) { + vfs_smr_exit(); ncp = NULL; } else { + vfs_smr_exit(); SDT_PROBE2(vfs, namecache, shrink_negative, done, ncp->nc_dvp, ncp->nc_name); - - cache_zap_locked(ncp, true); + cache_zap_locked(ncp); counter_u64_add(numneg_evicted, 1); } - mtx_unlock(&neglist->nl_lock); rw_wunlock(blp); mtx_unlock(dvlp); cache_free(ncp); @@ -913,7 +916,7 @@ cache_negative_zap_one(void) * pointer to a vnode or if it is just a negative cache entry. */ static void -cache_zap_locked(struct namecache *ncp, bool neg_locked) +cache_zap_locked(struct namecache *ncp) { if (!(ncp->nc_flag & NCF_NEGATIVE)) @@ -936,7 +939,7 @@ cache_zap_locked(struct namecache *ncp, bool neg_locked) } else { SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp, ncp->nc_name); - cache_negative_remove(ncp, neg_locked); + cache_negative_remove(ncp); } if (ncp->nc_flag & NCF_ISDOTDOT) { if (ncp == ncp->nc_dvp->v_cache_dd) @@ -962,7 +965,7 @@ cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp) blp = NCP2BUCKETLOCK(ncp); rw_wlock(blp); - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); rw_wunlock(blp); } @@ -1009,7 +1012,7 @@ cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp, } } rw_wlock(blp); - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); rw_wunlock(blp); if (to_unlock != NULL) mtx_unlock(to_unlock); @@ -1055,7 +1058,7 @@ cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp) to_unlock = vlp1; } rw_wlock(blp); - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); rw_wunlock(blp); mtx_unlock(to_unlock); out: @@ -1086,7 +1089,7 @@ cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, break; } if (rncp != NULL) { - cache_zap_locked(rncp, false); + cache_zap_locked(rncp); rw_wunlock(blp); cache_unlock_vnodes(dvlp, vlp); counter_u64_add(zap_and_exit_bucket_relock_success, 1); @@ -1112,7 +1115,7 @@ cache_zap_wlocked_bucket(struct namecache *ncp, struct componentname *cnp, if (!(ncp->nc_flag & NCF_NEGATIVE)) vlp = VP2VNODELOCK(ncp->nc_vp); if (cache_trylock_vnodes(dvlp, vlp) == 0) { - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); rw_wunlock(blp); cache_unlock_vnodes(dvlp, vlp); return (0); @@ -1139,7 +1142,7 @@ cache_zap_rlocked_bucket(struct namecache *ncp, struct componentname *cnp, if (cache_trylock_vnodes(dvlp, vlp) == 0) { rw_runlock(blp); rw_wlock(blp); - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); rw_wunlock(blp); cache_unlock_vnodes(dvlp, vlp); return (0); @@ -1165,7 +1168,7 @@ cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, cache_sort_vnodes(&dvlp, &vlp); if (*vlpp1 == dvlp && *vlpp2 == vlp) { - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); cache_unlock_vnodes(dvlp, vlp); *vlpp1 = NULL; *vlpp2 = NULL; @@ -1180,7 +1183,7 @@ cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp, *vlpp2 = NULL; if (cache_trylock_vnodes(dvlp, vlp) == 0) { - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); cache_unlock_vnodes(dvlp, vlp); return (0); } @@ -1798,7 +1801,7 @@ cache_enter_dotdot_prep(struct vnode *dvp, struct vnode *vp, ncp = dvp->v_cache_dd; if (ncp != NULL && (ncp->nc_flag & NCF_ISDOTDOT)) { KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent")); - cache_zap_locked(ncp, false); + cache_zap_locked(ncp); } else { ncp = NULL; } @@ -1929,7 +1932,7 @@ cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp, */ if ((ndd = vp->v_cache_dd) != NULL) { if ((ndd->nc_flag & NCF_ISDOTDOT) != 0) - cache_zap_locked(ndd, false); + cache_zap_locked(ndd); else ndd = NULL; }