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namecache: factor out dot lookup into a dedicated function

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The intent is to move uncommon cases out of the way.

MFC after:	1 week
This commit is contained in:
Mateusz Guzik 2017-09-08 06:51:33 +00:00
parent 6a569d3525
commit da8f32a7f1
1 changed files with 38 additions and 30 deletions
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68
sys/kern/vfs_cache.c
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@ -1073,6 +1073,42 @@ cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp)
}
}
static int __noinline
cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
struct timespec *tsp, int *ticksp)
{
int ltype;
*vpp = dvp;
CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
dvp, cnp->cn_nameptr);
counter_u64_add(dothits, 1);
SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
if (tsp != NULL)
timespecclear(tsp);
if (ticksp != NULL)
*ticksp = ticks;
vrefact(*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);
}
/*
* Lookup an entry in the cache
*
@ -1111,36 +1147,8 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
counter_u64_add(numcalls, 1);
if (cnp->cn_nameptr[0] == '.') {
if (cnp->cn_namelen == 1) {
*vpp = dvp;
CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
dvp, cnp->cn_nameptr);
counter_u64_add(dothits, 1);
SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
if (tsp != NULL)
timespecclear(tsp);
if (ticksp != NULL)
*ticksp = ticks;
vrefact(*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 (cnp->cn_namelen == 1)
return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp));
if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
counter_u64_add(dotdothits, 1);
dvlp2 = NULL;