[PATCH 6.1.y 03/18] NFSD: Refactor nfsd_reply_cache_free_locked()

cel
2024-08-10T20:00:39Z

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit 35308e7f0fc3942edc87d9c6dc78c4a096428957 ]

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>.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Stable-dep-of: a9507f6af145 ("NFSD: Replace nfsd_prune_bucket()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
fs/nfsd/nfscache.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 2c6942e2344c..11d00b2853ff 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -110,21 +110,33 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum,
return rp;
}

-static void
-nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
- struct nfsd_net *nn)
+static void nfsd_cacherep_free(struct svc_cacherep *rp)
{
- if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
- nfsd_stats_drc_mem_usage_sub(nn, rp->c_replvec.iov_len);
+ if (rp->c_type == RC_REPLBUFF)
kfree(rp->c_replvec.iov_base);
- }
+ kmem_cache_free(drc_slab, rp);
+}
+
+static void
+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)
+ nfsd_stats_drc_mem_usage_sub(nn, rp->c_replvec.iov_len);
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 +144,9 @@ 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)
--
2.45.1