[PATCH RFC 3/6] sunrpc: track the max number of requested threads in a pool

[Jeff Layton <jlayton@kernel.org>]

The kernel currently tracks the number of threads running in a pool in
the "sp_nrthreads" field. In the future, where threads are dynamically
spun up and down, it'll be necessary to keep track of the maximum number
of requested threads separately from the actual number running.

Add a pool->sp_nrthrmax parameter to track this. When userland changes
the number of threads in a pool, update that value accordingly.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/sunrpc/svc.h | 3 ++-
 net/sunrpc/svc.c           | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index dd5fbbf8b3d39df6c17a7624edf344557fffd32c..ee9260ca908c907f4373f4cfa471b272bc7bcc8c 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -35,8 +35,9 @@
  */
 struct svc_pool {
 	unsigned int		sp_id;		/* pool id; also node id on NUMA */
+	unsigned int		sp_nrthreads;	/* # of threads currently running in pool */
+	unsigned int		sp_nrthrmax;	/* Max requested number of threads in pool */
 	struct lwq		sp_xprts;	/* pending transports */
-	unsigned int		sp_nrthreads;	/* # of threads in pool */
 	struct list_head	sp_all_threads;	/* all server threads */
 	struct llist_head	sp_idle_threads; /* idle server threads */
 
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 3484c587a108e6f34e5c23edaf8f3a3c169c9e4a..8cd45f62ef74af6e0826b8f13cc903b0962af5e0 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -836,6 +836,7 @@ svc_set_pool_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
 	if (!pool)
 		return -EINVAL;
 
+	pool->sp_nrthrmax = nrservs;
 	nrservs -= pool->sp_nrthreads;
 
 	if (nrservs > 0)

-- 
2.52.0