ceph: release unreserved caps if having enough available caps

When unreserving caps check if there is too mamy available caps
in the ->caps_list, if so release unreserved caps.

Signed-off-by: Chengguang Xu <cgxu519@icloud.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 421cdce71fb0..b9b5c47efd06 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -254,12 +254,26 @@ out_nomem:
 int ceph_unreserve_caps(struct ceph_mds_client *mdsc,
                         struct ceph_cap_reservation *ctx)
 {
+        int i;
+        struct ceph_cap *cap;
+
         dout("unreserve caps ctx=%p count=%d\n", ctx, ctx->count);
         if (ctx->count) {
                 spin_lock(&mdsc->caps_list_lock);
                 BUG_ON(mdsc->caps_reserve_count < ctx->count);
                 mdsc->caps_reserve_count -= ctx->count;
-                mdsc->caps_avail_count += ctx->count;
+                if (mdsc->caps_avail_count >=
+                    mdsc->caps_reserve_count + mdsc->caps_min_count) {
+                        mdsc->caps_total_count -= ctx->count;
+                        for (i = 0; i < ctx->count; i++) {
+                                cap = list_first_entry(&mdsc->caps_list,
+                                        struct ceph_cap, caps_item);
+                                list_del(&cap->caps_item);
+                                kmem_cache_free(ceph_cap_cachep, cap);
+                        }
+                } else {
+                        mdsc->caps_avail_count += ctx->count;
+                }
                 ctx->count = 0;
                 dout("unreserve caps %d = %d used + %d resv + %d avail\n",
                      mdsc->caps_total_count, mdsc->caps_use_count,