From: Chuck Lever <chuck.lever@xxxxxxxxxx>
To reduce contention on the bucket locks, we must avoid calling
kfree() while each bucket lock is held.
Start by refactoring nfsd_reply_cache_free_locked() into a helper
that removes an entry from the bucket (and must therefore run under
the lock) and a second helper that frees the entry (which does not
need to hold the lock).
For readability, rename the helpers nfsd_cacherep_<verb>.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/nfscache.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index a8eda1c85829..601298b7f75f 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -110,21 +110,32 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum,
return rp;
}
+static void nfsd_cacherep_free(struct svc_cacherep *rp)
+{
+ kfree(rp->c_replvec.iov_base);
+ kmem_cache_free(drc_slab, rp);
+}
+
static void
-nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
- struct nfsd_net *nn)
+nfsd_cacherep_unlink_locked(struct nfsd_net *nn, struct nfsd_drc_bucket *b,
+ struct svc_cacherep *rp)
{
- if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
+ if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base)
nfsd_stats_drc_mem_usage_sub(nn, rp->c_replvec.iov_len);
- kfree(rp->c_replvec.iov_base);
- }
if (rp->c_state != RC_UNUSED) {
rb_erase(&rp->c_node, &b->rb_head);
list_del(&rp->c_lru);
atomic_dec(&nn->num_drc_entries);
nfsd_stats_drc_mem_usage_sub(nn, sizeof(*rp));
}
- kmem_cache_free(drc_slab, rp);
+}
+
+static void
+nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
+ struct nfsd_net *nn)
+{
+ nfsd_cacherep_unlink_locked(nn, b, rp);
+ nfsd_cacherep_free(rp);
}
static void
@@ -132,8 +143,9 @@ nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
struct nfsd_net *nn)
{
spin_lock(&b->cache_lock);
- nfsd_reply_cache_free_locked(b, rp, nn);
+ nfsd_cacherep_unlink_locked(nn, b, rp);
spin_unlock(&b->cache_lock);
+ nfsd_cacherep_free(rp);
}
int nfsd_drc_slab_create(void)
