> On 24 Feb 2018, at 18:35, Chengguang Xu <cgxu519@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxx>
> ---
> Only compile tested.
>
> fs/ceph/caps.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 6582c45..b598a24 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -280,6 +280,23 @@ struct ceph_cap *ceph_get_cap(struct ceph_mds_client *mdsc,
> /* temporary, until we do something about cap import/export */
> if (!ctx) {
> cap = kmem_cache_alloc(ceph_cap_cachep, GFP_NOFS);
> + if (!cap) {
> + 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);
> + }
> +
should skip executing following code. I fixed it locally
> if (cap) {
> spin_lock(&mdsc->caps_list_lock);
> mdsc->caps_use_count++;
> --
> 1.8.3.1
>
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