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nfsd: don't try to reuse an expired DRC entry off the list

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Currently when we are processing a request, we try to scrape an expired
or over-limit entry off the list in preference to allocating a new one
from the slab.

This is unnecessarily complicated. Just use the slab layer.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Jeff Layton 2013-12-05 06:00:51 -05:00 committed by J. Bruce Fields
parent 28303ca309
commit a0ef5e1968
1 changed files with 4 additions and 32 deletions
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36
fs/nfsd/nfscache.c
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@ -131,13 +131,6 @@ nfsd_reply_cache_alloc(void)
return rp;
}
static void
nfsd_reply_cache_unhash(struct svc_cacherep *rp)
{
hlist_del_init(&rp->c_hash);
list_del_init(&rp->c_lru);
}
static void
nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
{
@ -416,22 +409,8 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
/*
* Since the common case is a cache miss followed by an insert,
* preallocate an entry. First, try to reuse the first entry on the LRU
* if it works, then go ahead and prune the LRU list.
* preallocate an entry.
*/
spin_lock(&cache_lock);
if (!list_empty(&lru_head)) {
rp = list_first_entry(&lru_head, struct svc_cacherep, c_lru);
if (nfsd_cache_entry_expired(rp) ||
num_drc_entries >= max_drc_entries) {
nfsd_reply_cache_unhash(rp);
prune_cache_entries();
goto search_cache;
}
}
/* No expired ones available, allocate a new one. */
spin_unlock(&cache_lock);
rp = nfsd_reply_cache_alloc();
spin_lock(&cache_lock);
if (likely(rp)) {
@ -439,7 +418,9 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
drc_mem_usage += sizeof(*rp);
}
search_cache:
/* go ahead and prune the cache */
prune_cache_entries();
found = nfsd_cache_search(rqstp, csum);
if (found) {
if (likely(rp))
@ -453,15 +434,6 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
goto out;
}
/*
* We're keeping the one we just allocated. Are we now over the
* limit? Prune one off the tip of the LRU in trade for the one we
* just allocated if so.
*/
if (num_drc_entries >= max_drc_entries)
nfsd_reply_cache_free_locked(list_first_entry(&lru_head,
struct svc_cacherep, c_lru));
nfsdstats.rcmisses++;
rqstp->rq_cacherep = rp;
rp->c_state = RC_INPROG;