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authorMateusz Guzik <mjg@FreeBSD.org>2020-08-26 12:50:57 +0000
committerMateusz Guzik <mjg@FreeBSD.org>2020-08-26 12:50:57 +0000
commit32f3d0821ca605059ff3d22a349329ab488fce51 (patch)
treedf864da13039d33b2965238936eb7ce2657ad660
parent935e15187c1a4f837bb0a00c019587486eb29d87 (diff)
downloadsrc-32f3d0821ca605059ff3d22a349329ab488fce51.tar.gz
src-32f3d0821ca605059ff3d22a349329ab488fce51.zip
cache: only evict negative entries on CREATE when ISLASTCN is set
Notes
Notes: svn path=/head/; revision=364812
-rw-r--r--sys/kern/vfs_cache.c50
1 files changed, 27 insertions, 23 deletions
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index a8c67d618e05..ed2d4fd3f215 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -1398,15 +1398,17 @@ retry:
return (-1);
negative_success:
if (__predict_false(cnp->cn_nameiop == CREATE)) {
- counter_u64_add(numnegzaps, 1);
- error = cache_zap_locked_vnode(ncp, dvp);
- if (__predict_false(error != 0)) {
- zap_and_exit_bucket_fail2++;
- cache_maybe_yield();
- goto retry;
+ 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++;
+ cache_maybe_yield();
+ goto retry;
+ }
+ cache_free(ncp);
+ return (0);
}
- cache_free(ncp);
- return (0);
}
SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name);
@@ -1603,15 +1605,17 @@ retry:
negative_success:
/* We found a negative match, and want to create it, so purge */
if (__predict_false(cnp->cn_nameiop == CREATE)) {
- counter_u64_add(numnegzaps, 1);
- error = cache_zap_rlocked_bucket(ncp, cnp, hash, blp);
- if (__predict_false(error != 0)) {
- zap_and_exit_bucket_fail2++;
- cache_maybe_yield();
- goto retry;
+ 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++;
+ cache_maybe_yield();
+ goto retry;
+ }
+ cache_free(ncp);
+ return (0);
}
- cache_free(ncp);
- return (0);
}
SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name);
@@ -1658,13 +1662,6 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
return (0);
}
- /*
- * TODO: we only fallback becasue if a negative entry is found it will
- * need to be purged.
- */
- if (cnp->cn_nameiop == CREATE)
- goto out_fallback;
-
hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
vfs_smr_enter();
@@ -1723,6 +1720,13 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
return (-1);
negative_success:
+ if (__predict_false(cnp->cn_nameiop == CREATE)) {
+ if (cnp->cn_flags & ISLASTCN) {
+ vfs_smr_exit();
+ goto out_fallback;
+ }
+ }
+
SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name);
cache_out_ts(ncp, tsp, ticksp);
counter_u64_add(numneghits, 1);