Author: mjg
Date: Thu Sep 24 03:38:32 2020
New Revision: 366099
URL: https://svnweb.freebsd.org/changeset/base/366099
Log:
cache: eliminate cache_zap_locked_vnode
It is only ever called for negative entries and for those it is
just a wrapper around cache_zap_negative_locked_vnode_kl which
always succeeds.
This also fixes a bug where cache_lookup_fallback should have been
calling cache_zap_locked_bucket instead. Note that in order to trigger
the bug NOCACHE must not be set, which currently only happens when
creating a new coredump (and then the coredump-to-be has to have a
negative entry).
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Thu Sep 24 02:44:58 2020 (r366098)
+++ head/sys/kern/vfs_cache.c Thu Sep 24 03:38:32 2020 (r366099)
@@ -1089,52 +1089,6 @@ out_relock:
return (false);
}
-static int __noinline
-cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp)
-{
- struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
- struct mtx *blp;
- int error = 0;
-
- MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
- cache_assert_vnode_locked(vp);
-
- pvlp = VP2VNODELOCK(vp);
- if (ncp->nc_flag & NCF_NEGATIVE) {
- cache_zap_negative_locked_vnode_kl(ncp, vp);
- goto out;
- }
-
- blp = NCP2BUCKETLOCK(ncp);
- vlp1 = VP2VNODELOCK(ncp->nc_dvp);
- vlp2 = VP2VNODELOCK(ncp->nc_vp);
- cache_sort_vnodes(&vlp1, &vlp2);
- if (vlp1 == pvlp) {
- mtx_lock(vlp2);
- to_unlock = vlp2;
- } else {
- if (!mtx_trylock(vlp1)) {
- /*
- * TODO: Very wasteful but rare.
- */
- mtx_unlock(pvlp);
- mtx_lock(vlp1);
- mtx_lock(vlp2);
- mtx_unlock(vlp2);
- mtx_unlock(vlp1);
- return (EAGAIN);
- }
- to_unlock = vlp1;
- }
- mtx_lock(blp);
- cache_zap_locked(ncp);
- mtx_unlock(blp);
- mtx_unlock(to_unlock);
-out:
- mtx_unlock(pvlp);
- return (error);
-}
-
/*
* If trylocking failed we can get here. We know enough to take all needed
locks
* in the right order and re-lookup the entry.
@@ -1373,11 +1327,8 @@ negative_success:
if (__predict_false(cnp->cn_nameiop == CREATE)) {
if (cnp->cn_flags & ISLASTCN) {
counter_u64_add(numnegzaps, 1);
- error = cache_zap_locked_vnode(ncp, dvp);
- if (__predict_false(error != 0)) {
- zap_and_exit_bucket_fail2++;
- goto retry;
- }
+ cache_zap_negative_locked_vnode_kl(ncp, dvp);
+ mtx_unlock(dvlp);
cache_free(ncp);
return (0);
}
@@ -1484,7 +1435,7 @@ negative_success:
if (__predict_false(cnp->cn_nameiop == CREATE)) {
if (cnp->cn_flags & ISLASTCN) {
counter_u64_add(numnegzaps, 1);
- error = cache_zap_locked_vnode(ncp, dvp);
+ error = cache_zap_locked_bucket(ncp, cnp, hash, blp);
if (__predict_false(error != 0)) {
zap_and_exit_bucket_fail2++;
goto retry;
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