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NFSD: Replace nfsd_prune_bucket()

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[ Upstream commit a9507f6af1450ed26a4a36d979af518f5bb21e5d ]

Enable nfsd_prune_bucket() to drop the bucket lock while calling
kfree(). Use the same pattern that Jeff recently introduced in the
NFSD filecache.

A few percpu operations are moved outside the lock since they
temporarily disable local IRQs which is expensive and does not
need to be done while the lock is held.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Stable-dep-of: c135e1269f34 ("NFSD: Refactor the duplicate reply cache shrinker")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chuck Lever 2024-09-05 11:30:47 -04:00 committed by Greg Kroah-Hartman
parent a02f9d6ea3
commit 895807268a
2 changed files with 85 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
fs/nfsd/nfscache.c
View File

@ -117,6 +117,21 @@ static void nfsd_cacherep_free(struct svc_cacherep *rp)
kmem_cache_free(drc_slab, rp);
}
static unsigned long
nfsd_cacherep_dispose(struct list_head *dispose)
{
struct svc_cacherep *rp;
unsigned long freed = 0;
while (!list_empty(dispose)) {
rp = list_first_entry(dispose, struct svc_cacherep, c_lru);
list_del(&rp->c_lru);
nfsd_cacherep_free(rp);
freed++;
}
return freed;
}
static void
nfsd_cacherep_unlink_locked(struct nfsd_net *nn, struct nfsd_drc_bucket *b,
struct svc_cacherep *rp)
@ -259,6 +274,41 @@ nfsd_cache_bucket_find(__be32 xid, struct nfsd_net *nn)
return &nn->drc_hashtbl[hash];
}
/*
* Remove and return no more than @max expired entries in bucket @b.
* If @max is zero, do not limit the number of removed entries.
*/
static void
nfsd_prune_bucket_locked(struct nfsd_net *nn, struct nfsd_drc_bucket *b,
unsigned int max, struct list_head *dispose)
{
unsigned long expiry = jiffies - RC_EXPIRE;
struct svc_cacherep *rp, *tmp;
unsigned int freed = 0;
lockdep_assert_held(&b->cache_lock);
/* The bucket LRU is ordered oldest-first. */
list_for_each_entry_safe(rp, tmp, &b->lru_head, c_lru) {
/*
* Don't free entries attached to calls that are still
* in-progress, but do keep scanning the list.
*/
if (rp->c_state == RC_INPROG)
continue;
if (atomic_read(&nn->num_drc_entries) <= nn->max_drc_entries &&
time_before(expiry, rp->c_timestamp))
break;
nfsd_cacherep_unlink_locked(nn, b, rp);
list_add(&rp->c_lru, dispose);
if (max && ++freed > max)
break;
}
}
static long prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn,
unsigned int max)
{
@ -282,11 +332,6 @@ static long prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn,
return freed;
}
static long nfsd_prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn)
{
return prune_bucket(b, nn, 3);
}
/*
* Walk the LRU list and prune off entries that are older than RC_EXPIRE.
* Also prune the oldest ones when the total exceeds the max number of entries.
@ -442,6 +487,8 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
__wsum csum;
struct nfsd_drc_bucket *b;
int type = rqstp->rq_cachetype;
unsigned long freed;
LIST_HEAD(dispose);
int rtn = RC_DOIT;
rqstp->rq_cacherep = NULL;
@ -466,20 +513,18 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
found = nfsd_cache_insert(b, rp, nn);
if (found != rp)
goto found_entry;
nfsd_stats_rc_misses_inc();
rqstp->rq_cacherep = rp;
rp->c_state = RC_INPROG;
nfsd_prune_bucket_locked(nn, b, 3, &dispose);
spin_unlock(&b->cache_lock);
freed = nfsd_cacherep_dispose(&dispose);
trace_nfsd_drc_gc(nn, freed);
nfsd_stats_rc_misses_inc();
atomic_inc(&nn->num_drc_entries);
nfsd_stats_drc_mem_usage_add(nn, sizeof(*rp));
nfsd_prune_bucket(b, nn);
out_unlock:
spin_unlock(&b->cache_lock);
out:
return rtn;
goto out;
found_entry:
/* We found a matching entry which is either in progress or done. */
@ -517,7 +562,10 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
out_trace:
trace_nfsd_drc_found(nn, rqstp, rtn);
goto out_unlock;
out_unlock:
spin_unlock(&b->cache_lock);
out:
return rtn;
}
/**

22
fs/nfsd/trace.h
View File

@ -1171,6 +1171,28 @@ TRACE_EVENT(nfsd_drc_mismatch,
__entry->ingress)
);
TRACE_EVENT_CONDITION(nfsd_drc_gc,
TP_PROTO(
const struct nfsd_net *nn,
unsigned long freed
),
TP_ARGS(nn, freed),
TP_CONDITION(freed > 0),
TP_STRUCT__entry(
__field(unsigned long long, boot_time)
__field(unsigned long, freed)
__field(int, total)
),
TP_fast_assign(
__entry->boot_time = nn->boot_time;
__entry->freed = freed;
__entry->total = atomic_read(&nn->num_drc_entries);
),
TP_printk("boot_time=%16llx total=%d freed=%lu",
__entry->boot_time, __entry->total, __entry->freed
)
);
TRACE_EVENT(nfsd_cb_args,
TP_PROTO(
const struct nfs4_client *clp,