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cache: put all negative entry management code into dedicated functions

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Reviewed by:	kib
MFC after:	1 week
This commit is contained in:
Mateusz Guzik 2016-09-04 08:55:15 +00:00
parent eb83f2e1ea
commit b9042ae1bf
1 changed files with 51 additions and 22 deletions
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73
sys/kern/vfs_cache.c
View file

@ -432,6 +432,50 @@ SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD|
"nchash statistics (number of total/used buckets, maximum chain length, usage percentage)");
#endif
/*
* Negative entries management
*/
static void
cache_negative_hit(struct namecache *ncp)
{
rw_assert(&cache_lock, RA_WLOCKED);
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
}
static void
cache_negative_insert(struct namecache *ncp)
{
rw_assert(&cache_lock, RA_WLOCKED);
MPASS(ncp->nc_vp == NULL);
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
numneg++;
}
static void
cache_negative_remove(struct namecache *ncp)
{
rw_assert(&cache_lock, RA_WLOCKED);
MPASS(ncp->nc_vp == NULL);
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
numneg--;
}
static void
cache_negative_zap_one(void)
{
struct namecache *ncp;
rw_assert(&cache_lock, RA_WLOCKED);
ncp = TAILQ_FIRST(&ncneg);
KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg",
ncp, ncp->nc_vp));
cache_zap(ncp);
}
/*
* cache_zap():
*
@ -469,8 +513,7 @@ cache_zap(struct namecache *ncp)
if (ncp == ncp->nc_vp->v_cache_dd)
ncp->nc_vp->v_cache_dd = NULL;
} else {
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
numneg--;
cache_negative_remove(ncp);
}
numcache--;
cache_free(ncp);
@ -640,14 +683,7 @@ negative_success:
if (!wlocked && !CACHE_UPGRADE_LOCK())
goto wlock;
counter_u64_add(numneghits, 1);
/*
* We found a "negative" match, so we shift it to the end of
* the "negative" cache entries queue to satisfy LRU. Also,
* check to see if the entry is a whiteout; indicate this to
* the componentname, if so.
*/
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
cache_negative_hit(ncp);
if (ncp->nc_flag & NCF_WHITE)
cnp->cn_flags |= ISWHITEOUT;
SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp,
@ -759,15 +795,13 @@ cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst,
ncp, nc_dst);
} else {
TAILQ_REMOVE(&ncneg, ncp, nc_dst);
numneg--;
cache_negative_remove(ncp);
}
if (vp != NULL) {
TAILQ_INSERT_HEAD(&vp->v_cache_dst,
ncp, nc_dst);
} else {
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
numneg++;
cache_negative_insert(ncp);
}
ncp->nc_vp = vp;
CACHE_WUNLOCK();
@ -893,17 +927,12 @@ cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
} else {
if (cnp->cn_flags & ISWHITEOUT)
ncp->nc_flag |= NCF_WHITE;
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
numneg++;
cache_negative_insert(ncp);
SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
nc_get_name(ncp));
}
if (numneg * ncnegfactor > numcache) {
ncp = TAILQ_FIRST(&ncneg);
KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg",
ncp, ncp->nc_vp));
cache_zap(ncp);
}
if (numneg * ncnegfactor > numcache)
cache_negative_zap_one();
CACHE_WUNLOCK();
}