Author: mjg
Date: Wed Aug 26 12:49:39 2020
New Revision: 364810
URL: https://svnweb.freebsd.org/changeset/base/364810
Log:
cache: factor dotdot lookup out of cache_lookup
Tested by: pho
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Wed Aug 26 10:21:38 2020 (r364809)
+++ head/sys/kern/vfs_cache.c Wed Aug 26 12:49:39 2020 (r364810)
@@ -1273,14 +1273,10 @@ cache_zap_wlocked_bucket_kl(struct namecache *ncp, str
}
static void
-cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp)
+cache_lookup_unlock(struct rwlock *blp)
{
- if (blp != NULL) {
- rw_runlock(blp);
- } else {
- mtx_unlock(vlp);
- }
+ rw_runlock(blp);
}
static int __noinline
@@ -1320,6 +1316,111 @@ cache_lookup_dot(struct vnode *dvp, struct vnode **vpp
}
static __noinline int
+cache_remove_cnp(struct vnode *dvp, struct componentname *cnp);
+
+
+static int __noinline
+cache_lookup_dotdot(struct vnode *dvp, struct vnode **vpp, struct
componentname *cnp,
+ struct timespec *tsp, int *ticksp)
+{
+ struct namecache_ts *ncp_ts;
+ struct namecache *ncp;
+ struct mtx *dvlp;
+ enum vgetstate vs;
+ int error, ltype;
+ bool whiteout;
+
+ MPASS((cnp->cn_flags & ISDOTDOT) != 0);
+
+ if ((cnp->cn_flags & MAKEENTRY) == 0) {
+ cache_remove_cnp(dvp, cnp);
+ return (0);
+ }
+
+ counter_u64_add(dotdothits, 1);
+retry:
+ dvlp = VP2VNODELOCK(dvp);
+ mtx_lock(dvlp);
+ ncp = dvp->v_cache_dd;
+ if (ncp == NULL) {
+ SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
+ "..", NULL);
+ mtx_unlock(dvlp);
+ return (0);
+ }
+ if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
+ if (ncp->nc_flag & NCF_NEGATIVE)
+ *vpp = NULL;
+ else
+ *vpp = ncp->nc_vp;
+ } else
+ *vpp = ncp->nc_dvp;
+ /* Return failure if negative entry was found. */
+ if (*vpp == NULL)
+ goto negative_success;
+ CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
+ dvp, cnp->cn_nameptr, *vpp);
+ SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..",
+ *vpp);
+ cache_out_ts(ncp, tsp, ticksp);
+ if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
+ NCF_DTS && tsp != NULL) {
+ ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
+ *tsp = ncp_ts->nc_dotdottime;
+ }
+
+ /*
+ * On success we return a locked and ref'd vnode as per the lookup
+ * protocol.
+ */
+ MPASS(dvp != *vpp);
+ ltype = 0; /* silence gcc warning */
+ ltype = VOP_ISLOCKED(dvp);
+ VOP_UNLOCK(dvp);
+ vs = vget_prep(*vpp);
+ mtx_unlock(dvlp);
+ error = vget_finish(*vpp, cnp->cn_lkflags, vs);
+ vn_lock(dvp, ltype | LK_RETRY);
+ if (VN_IS_DOOMED(dvp)) {
+ if (error == 0)
+ vput(*vpp);
+ *vpp = NULL;
+ return (ENOENT);
+ }
+ if (error) {
+ *vpp = NULL;
+ goto retry;
+ }
+ if ((cnp->cn_flags & ISLASTCN) &&
+ (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
+ ASSERT_VOP_ELOCKED(*vpp, "cache_lookup");
+ }
+ 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;
+ }
+ cache_free(ncp);
+ return (0);
+ }
+
+ SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name);
+ cache_out_ts(ncp, tsp, ticksp);
+ counter_u64_add(numneghits, 1);
+ whiteout = (ncp->nc_flag & NCF_WHITE);
+ cache_negative_hit(ncp);
+ mtx_unlock(dvlp);
+ if (whiteout)
+ cnp->cn_flags |= ISWHITEOUT;
+ return (ENOENT);
+}
+
+static __noinline int
cache_remove_cnp(struct vnode *dvp, struct componentname *cnp)
{
struct namecache *ncp;
@@ -1441,14 +1542,12 @@ int
cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
struct timespec *tsp, int *ticksp)
{
- struct namecache_ts *ncp_ts;
struct namecache *ncp;
struct negstate *negstate;
struct rwlock *blp;
- struct mtx *dvlp;
uint32_t hash;
enum vgetstate vs;
- int error, ltype;
+ int error;
bool try_smr, doing_smr, whiteout;
#ifdef DEBUG_CACHE
@@ -1458,9 +1557,15 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, st
}
#endif
- if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.'))
- return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp));
+ if (__predict_false(cnp->cn_nameptr[0] == '.')) {
+ if (cnp->cn_namelen == 1)
+ return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp));
+ if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.')
+ return (cache_lookup_dotdot(dvp, vpp, cnp, tsp,
ticksp));
+ }
+ MPASS((cnp->cn_flags & ISDOTDOT) == 0);
+
if ((cnp->cn_flags & MAKEENTRY) == 0) {
cache_remove_cnp(dvp, cnp);
return (0);
@@ -1472,42 +1577,7 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, st
retry:
doing_smr = false;
blp = NULL;
- dvlp = NULL;
error = 0;
- if (cnp->cn_namelen == 2 &&
- cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') {
- counter_u64_add(dotdothits, 1);
- dvlp = VP2VNODELOCK(dvp);
- mtx_lock(dvlp);
- ncp = dvp->v_cache_dd;
- if (ncp == NULL) {
- SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
- "..", NULL);
- mtx_unlock(dvlp);
- return (0);
- }
- if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
- if (ncp->nc_flag & NCF_NEGATIVE)
- *vpp = NULL;
- else
- *vpp = ncp->nc_vp;
- } else
- *vpp = ncp->nc_dvp;
- /* Return failure if negative entry was found. */
- if (*vpp == NULL)
- goto negative_success;
- CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
- dvp, cnp->cn_nameptr, *vpp);
- SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..",
- *vpp);
- cache_out_ts(ncp, tsp, ticksp);
- if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
- NCF_DTS && tsp != NULL) {
- ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
- *tsp = ncp_ts->nc_dotdottime;
- }
- goto success;
- }
hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
retry_hashed:
@@ -1549,17 +1619,11 @@ retry_hashed:
SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name,
*vpp);
cache_out_ts(ncp, tsp, ticksp);
-success:
/*
* On success we return a locked and ref'd vnode as per the lookup
* protocol.
*/
MPASS(dvp != *vpp);
- ltype = 0; /* silence gcc warning */
- if (cnp->cn_flags & ISDOTDOT) {
- ltype = VOP_ISLOCKED(dvp);
- VOP_UNLOCK(dvp);
- }
if (doing_smr) {
if (!cache_ncp_canuse(ncp)) {
vfs_smr_exit();
@@ -1574,18 +1638,9 @@ success:
}
} else {
vs = vget_prep(*vpp);
- cache_lookup_unlock(blp, dvlp);
+ cache_lookup_unlock(blp);
}
error = vget_finish(*vpp, cnp->cn_lkflags, vs);
- if (cnp->cn_flags & ISDOTDOT) {
- vn_lock(dvp, ltype | LK_RETRY);
- if (VN_IS_DOOMED(dvp)) {
- if (error == 0)
- vput(*vpp);
- *vpp = NULL;
- return (ENOENT);
- }
- }
if (error) {
*vpp = NULL;
goto retry;
@@ -1598,10 +1653,17 @@ success:
negative_success:
/* We found a negative match, and want to create it, so purge */
- if (cnp->cn_nameiop == CREATE) {
+ if (__predict_false(cnp->cn_nameiop == CREATE)) {
MPASS(!doing_smr);
counter_u64_add(numnegzaps, 1);
- goto zap_and_exit;
+ error = cache_zap_rlocked_bucket(ncp, cnp, hash, blp);
+ if (__predict_false(error != 0)) {
+ zap_and_exit_bucket_fail2++;
+ cache_maybe_yield();
+ goto retry;
+ }
+ cache_free(ncp);
+ return (0);
}
SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name);
@@ -1623,25 +1685,11 @@ negative_success:
vfs_smr_exit();
} else {
cache_negative_hit(ncp);
- cache_lookup_unlock(blp, dvlp);
+ cache_lookup_unlock(blp);
}
if (whiteout)
cnp->cn_flags |= ISWHITEOUT;
return (ENOENT);
-
-zap_and_exit:
- MPASS(!doing_smr);
- if (blp != NULL)
- error = cache_zap_rlocked_bucket(ncp, cnp, hash, blp);
- else
- 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);
}
struct celockstate {
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