From: Chengguang Xu <cgxu519@icloud.com>
Date: Sat, 24 Feb 2018 18:35:29 +0800
Subject: ceph: optimizing cap allocation
Git-commit: e327ce068518e38c0182739e879b9dce477c8d85
Patch-mainline: v4.17-rc1
References: bsc#1089115
When setting high volume of caps_min_count or having many
unreserved caps, unused caps may always keep in the ->caps_list
even can't get new cap from kmem_cache_alloc because lack of
maximum limitation of caps_avail_count. Hence reuse caps in
->caps_list if available, it's maybe better than setting max
limitation of caps_avail_count and releasing unused caps when
reaching the limit.
Signed-off-by: Chengguang Xu <cgxu519@icloud.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
fs/ceph/caps.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -284,7 +284,23 @@ struct ceph_cap *ceph_get_cap(struct cep
mdsc->caps_use_count++;
mdsc->caps_total_count++;
spin_unlock(&mdsc->caps_list_lock);
+ } else {
+ spin_lock(&mdsc->caps_list_lock);
+ if (mdsc->caps_avail_count) {
+ BUG_ON(list_empty(&mdsc->caps_list));
+
+ mdsc->caps_avail_count--;
+ mdsc->caps_use_count++;
+ cap = list_first_entry(&mdsc->caps_list,
+ struct ceph_cap, caps_item);
+ list_del(&cap->caps_item);
+
+ BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
+ mdsc->caps_reserve_count + mdsc->caps_avail_count);
+ }
+ spin_unlock(&mdsc->caps_list_lock);
}
+
return cap;
}