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cache: make ->nc_flag accesses atomic-clean for lockless usage

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This commit is contained in:
Mateusz Guzik 2021-01-25 21:58:59 +01:00
parent ffcf8f97f8
commit 6ef8fede86
1 changed files with 11 additions and 7 deletions
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18
sys/kern/vfs_cache.c
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@ -398,7 +398,7 @@ static inline struct negstate *
NCP2NEGSTATE(struct namecache *ncp)
{
MPASS(ncp->nc_flag & NCF_NEGATIVE);
MPASS(atomic_load_char(&ncp->nc_flag) & NCF_NEGATIVE);
return (&ncp->nc_neg);
}
@ -1994,7 +1994,7 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
}
cache_out_ts(ncp, tsp, ticksp);
whiteout = (ncp->nc_flag & NCF_WHITE);
whiteout = (atomic_load_char(&ncp->nc_flag) & NCF_WHITE);
neg_promote = cache_neg_hit_prep(ncp);
if (!cache_ncp_canuse(ncp)) {
cache_neg_hit_abort(ncp);
@ -2149,6 +2149,7 @@ cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
{
struct namecache *ncp;
struct mtx *blps[2];
u_char nc_flag;
blps[0] = HASH2BUCKETLOCK(hash);
for (;;) {
@ -2159,11 +2160,12 @@ cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
ncp = vp->v_cache_dd;
if (ncp == NULL)
break;
if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
nc_flag = atomic_load_char(&ncp->nc_flag);
if ((nc_flag & NCF_ISDOTDOT) == 0)
break;
MPASS(ncp->nc_dvp == vp);
blps[1] = NCP2BUCKETLOCK(ncp);
if (ncp->nc_flag & NCF_NEGATIVE)
if ((nc_flag & NCF_NEGATIVE) != 0)
break;
if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
break;
@ -2190,6 +2192,7 @@ cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp
{
struct namecache *ncp;
struct mtx *blps[2];
u_char nc_flag;
blps[0] = HASH2BUCKETLOCK(hash);
for (;;) {
@ -2198,11 +2201,12 @@ cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp
ncp = dvp->v_cache_dd;
if (ncp == NULL)
break;
if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
nc_flag = atomic_load_char(&ncp->nc_flag);
if ((nc_flag & NCF_ISDOTDOT) == 0)
break;
MPASS(ncp->nc_dvp == dvp);
blps[1] = NCP2BUCKETLOCK(ncp);
if (ncp->nc_flag & NCF_NEGATIVE)
if ((nc_flag & NCF_NEGATIVE) != 0)
break;
if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
break;
@ -2436,7 +2440,7 @@ cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
vp);
} else {
if (cnp->cn_flags & ISWHITEOUT)
ncp->nc_flag |= NCF_WHITE;
atomic_store_char(&ncp->nc_flag, ncp->nc_flag | NCF_WHITE);
cache_neg_insert(ncp);
SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
ncp->nc_name);