Author: mjg
Date: Thu Jan 21 01:07:05 2016
New Revision: 294477
URL: https://svnweb.freebsd.org/changeset/base/294477
Log:
cache: perform . lockup without the namecache lock
Reviewed by: kib
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Thu Jan 21 01:05:41 2016 (r294476)
+++ head/sys/kern/vfs_cache.c Thu Jan 21 01:07:05 2016 (r294477)
@@ -508,7 +508,6 @@ cache_lookup(struct vnode *dvp, struct v
return (0);
}
retry:
- CACHE_RLOCK();
wlocked = 0;
counter_u64_add(numcalls, 1);
error = 0;
@@ -525,8 +524,28 @@ retry_wlocked:
timespecclear(tsp);
if (ticksp != NULL)
*ticksp = ticks;
- goto success;
+ VREF(*vpp);
+ /*
+ * When we lookup "." we still can be asked to lock it
+ * differently...
+ */
+ ltype = cnp->cn_lkflags & LK_TYPE_MASK;
+ if (ltype != VOP_ISLOCKED(*vpp)) {
+ if (ltype == LK_EXCLUSIVE) {
+ vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
+ if ((*vpp)->v_iflag & VI_DOOMED) {
+ /* forced unmount */
+ vrele(*vpp);
+ *vpp = NULL;
+ return (ENOENT);
+ }
+ } else
+ vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
+ }
+ return (-1);
}
+ if (!wlocked)
+ CACHE_RLOCK();
if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
counter_u64_add(dotdothits, 1);
if (dvp->v_cache_dd == NULL) {
@@ -562,7 +581,8 @@ retry_wlocked:
nc_dotdottime;
goto success;
}
- }
+ } else if (!wlocked)
+ CACHE_RLOCK();
hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
@@ -652,31 +672,7 @@ success:
* On success we return a locked and ref'd vnode as per the lookup
* protocol.
*/
- if (dvp == *vpp) { /* lookup on "." */
- VREF(*vpp);
- if (wlocked)
- CACHE_WUNLOCK();
- else
- CACHE_RUNLOCK();
- /*
- * When we lookup "." we still can be asked to lock it
- * differently...
- */
- ltype = cnp->cn_lkflags & LK_TYPE_MASK;
- if (ltype != VOP_ISLOCKED(*vpp)) {
- if (ltype == LK_EXCLUSIVE) {
- vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
- if ((*vpp)->v_iflag & VI_DOOMED) {
- /* forced unmount */
- vrele(*vpp);
- *vpp = NULL;
- return (ENOENT);
- }
- } else
- vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
- }
- return (-1);
- }
+ MPASS(dvp != *vpp);
ltype = 0; /* silence gcc warning */
if (cnp->cn_flags & ISDOTDOT) {
ltype = VOP_ISLOCKED(dvp);
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